Safe Food


Safe Food

Causes of foodborne illness … Recommended safe cooking temperatures … How to use thermometers for food effectively … Cooking red meats and hamburgers, poultry, eggs, and fish safely … Buying pasteurized foods … Two rules for serving foods safely … Cooling and thawing safely … Guidelines for avoiding cross-contamination … Washing fruits and vegetables … Sanitizing food-contact surfaces … Chopping boards … Sanitizing drains and disposals, dishcloths, brushes, pot scratchers, sponges … Effects of washing in the dishwasher … Guide to Common Food Pathogens … What to do about contaminated foods … Reduced-oxygen or modified-atmosphere packaged foods … Cooking by-products: safe cooking with meats, fats, and oils

All of us who want to eat good home-cooked food owe it to ourselves, and to our friends and families, to educate or reeducate ourselves on the subject of food safety. For some years now, several circumstances of modern life have combined to create new risks of foodborne illness. First, there are a number of new, emerging pathogens, as well as virulent new strains of old ones, that can live in food and make us sick. Our parents and grandparents did not have to deal with E. coli O157:H7, Cyclospora, Cryptosporidium, Campylobacter, Listeria, and Yersinia, but we do. Second, the food industry has changed. Food comes to us not only from all over the country but from all over the world, and meats, poultry, and eggs are produced at huge, centralized, factory-like places. In some instances, such changes have meant that food is more likely to be contaminated with pathogens. At the same time, never were children so likely as they are today to grow up and leave their parents’ homes, remaining entirely uneducated in how to run a kitchen so as to keep food safe.

This chapter, therefore, offers a primer on food safety in the home kitchen, explaining how foodborne illness arises and what our chief means of preventing it are. Extremely effective and simple means of prevention are available to all of us. Yet it is so easy to succumb to irrational fears of food that newcomers to the art of running a kitchen should keep the following reminders in mind as they read. This chapter is full of information on dangers that you cannot see, taste, or smell, and you should learn about these and the simple steps you can take to reduce the risks from such hidden dangers. But it is as true as it ever was that most dangers of foodborne illness coincide with conditions that are not at all mysterious. Bad-tasting, moldy, discolored, or rotten food is far more likely to be unhealthy and unsafe than food that is not. Kitchens in which surfaces, dishes, pots and pans, and chopping boards are soiled with crumbs, grease, spills, and smears are more likely to cause illness than sparkling clean ones. Yes, there are cases in which people follow all the rules and still get sick. But it is overwhelmingly true that foodborne illness is the result of simple and obvious mishandling of food: we fail to wash our hands or our foods, to cook foods well, to refrigerate them promptly and effectively, and to avoid cross-contamination. Once you have adopted good basic kitchen and cooking habits, it is time to stop worrying. The food in our country is generally of high quality, and your careful handling of it gives you a comfortably wide margin of safety.

Foodborne Illness: In General

Every year, tens of millions of us suffer from foodborne illness. This is serious business: it can result in severe complications or death. As always, the very young, the very old, sick and immunosuppressed people, and pregnant women are more vulnerable to harm than others. Usually, however, illness caused by contaminated foods is more uncomfortable and humiliating than life-threatening.

When it happened to me, within hours of ingesting contaminated food I began to vomit and developed diarrhea. Within a couple of days I felt fine again. But many foodborne illnesses do not follow this pattern. For one thing, they may not appear until days after you ate the bad food. Staphylococcus aureus usually appears in two to three hours, salmonellosis in twelve to twenty-four hours, and botulism most commonly in twelve to thirty-six hours. But E. coli has an incubation period of about three to eight days; Campylobacter infection comes on in two to five days; Cyclospora may take a week to make you sick. Listeriosis can develop anywhere from one to ninety days after consumption, but a few weeks is typical. Diarrhea, cramps, and vomiting, which may be mild or severe, are common symptoms but are not universal. Some kinds of food poisoning cause weakness, chills or fever, headaches, blurred or double vision, difficulty in breathing, the symptoms of meningitis, or flulike illness.

All food contains microorganisms. Some are harmless or even beneficial. But others, called pathogens, can cause illness in one of two ways. First, they themselves can invade your body and make you ill when you eat food containing them. This is called infection by the microorganisms. Second, microorganisms can produce toxins—harmful chemicals—in food, which will make you ill when you eat the food even if the microorganisms that produced the toxins are destroyed. For example, the bacterium Staphylococcus aureus will be destroyed by cooking, but its toxin will withstand heat, refrigeration, and freezing. The toxin that causes deadly botulism, however, would be destroyed if boiled for ten or fifteen minutes. Illness caused by ingesting toxins is called intoxication (but this type of intoxication, of course, has nothing to do with drunkenness). To make your food safe, you must protect against infection with microorganisms that grow in foods and against poisoning, or intoxication, by toxins that microorganisms may have produced.

Like all living things, microorganisms need a favorable environment to survive and grow in, not too acidic or too alkaline,1 not too hot or too cold, free of chemicals that might poison them (such as disinfectants or acids), and providing adequate food and water. Some bacteria are hardy—like some plants and animals—and survive under extremely unfavorable conditions. Others are impervious to one set of hardships but vulnerable to another; perhaps they will survive freezing but not heat, or perhaps they can tolerate a salty medium but not an acidic one. Just like other living things, some microbes are tougher than others of the same type. And just like most plants and animals, they can often live for a while in bad conditions, say without food or water, and start to thrive when some comes along; during the bad times they may simply survive, dormant, without growing or multiplying. (The Guide to Common Food Pathogens, pages 178-86, gives a summary of basic facts pertaining to some common food pathogens.)

Much of our food potentially provides both nutrients and water along with other favorable conditions for luxuriant microbial growth. So do wet chopping boards, knives and utensils, food-soiled or wet countertops, sink basins, dishes, drains, sponges, pot scratchers, damp dish towels and dishcloths, and our own hands. A minuscule crumb of food is a mountain range of sustenance for millions of bacteria. Spills and sticky or oily surfaces provide ample supplies for veritable armies of microbes. By the same token, where things are clean and dry, bacteria and other microbes are going to be vastly reduced in number. Even a “clean” but wet countertop can be home to millions of bacteria, but you can create a staggeringly reduced bacterial count simply by drying it off and keeping it dry for a couple of hours. The simplest and most important rule of food safety is: keep your kitchen clean and dry.

The presence of pathogens in foods that you have consumed does not guarantee that you will become sick. That depends on many factors, including the state of your health and resistance and just how many microbes or how much toxin you consumed. To some extent, it even depends on what you are used to, as we all tend to become accustomed to the microbes we commonly encounter in our own homes. Infectious sickness follows only when you ingest an “infectious dose” of pathogens. (See chapter 30, “Peaceful Coexistence with Microbes,” pages 423-24.) Although it may take shockingly few microbes to give you certain kinds of food poisoning, for example by E. coli, there are many kinds, such as certain strains of salmonella, to which healthy adults may succumb only if they consume tens or even hundreds of thousands of the causative pathogen. More microbes also produce more toxin; and although the tiniest taste of some toxins, such as the one that causes botulism, can be deadly, generally you are worse off the more you take in. Thus the real goal of many kitchen safety rules is to create conditions in and around your food that are unfavorable to the growth and multiplication of dangerous microbes. That way, even if some bad ones do survive, there may be so few that they cannot make you sick, or you may get a mild illness rather than a severe one.


Safe Temperatures and the Importance of Using Thermometers. Our most important means of killing and reducing the numbers of pathogens in our foods is temperature control: refrigerated storage and adequate cooking. People knew this and made food safe long before they knew there were such things as bacteria. Today, most of our kitchen behavior continues to be intuitive and customary, not science-based. We make things safe by doing things the way our parents did. Food-safety experts, however, urge you to make a change and introduce to your kitchen and cooking customs safeguards that our parents and grandparents often did not have: use thermometers—to test food temperatures, refrigerator temperatures, and freezer temperatures. They mean going beyond the occasional use of a candy thermometer or meat thermometer for the turkey.

Most bacteria grow in the temperature range between 40° and 140°F and are destroyed at higher temperatures. Bacteria that cause foodborne illness usually multiply most rapidly at between 60° and 125°F. Molds, like bacteria, can grow over a broad temperature range. They usually grow best between 64° and 86°F and are destroyed at temperatures over 140°F.

We refrigerate foods at 40°F or below so as to create an environment unfavorable to the multiplication of microorganisms. Refrigeration slows down the growth of most microorganisms without killing them and without stopping their growth entirely. It keeps food from spoiling for a few days. But as all of us know from unpleasant experience, sooner or later even food stored in the refrigerator spoils or grows moldy; and some bacteria can grow better in cold temperatures than others. Your freezer, which should be kept at 0°F, keeps food much longer because temperatures this low generally stop microbial growth altogether. However, most bacteria are not killed by freezing either. They will again begin multiplying as soon as they are thawed and returned to the favorable temperature range. The foods may become inedible from other causes in the meantime: rancidity, loss of texture, drying out.

Temperatures above 160°F do not merely prevent growth but actually kill most microorganisms. This is why cooking is our most important defense against food poisoning. Some bacteria, however, form “spores,” hard shells that protect them from environmental dangers such as extreme heat. Such spores do not die but “rest” until conditions are favorable once again. Some bacterial spores are practically indomitable, surviving even boiling. Spores are one reason why food may become unsafe again even after cooking unless the food is kept in the proper temperature zone: when the food after cooking cools down to within the zone of temperatures favorable to bacteria, the spores that survived will start to grow again. (This is one of the key dangers to be guarded against in home canning. See the information about Clostridium botulinum in the Guide to Common Food Pathogens, pages 180-81.) Commercial canning processes use a combination of very high temperatures plus pressure, which can destroy spores, to achieve the impressive safety record of commercial canned goods. If you serve home-canned foods, especially those that are low in acid, such as stew or corn, the USDA recommends that you boil them for at least ten minutes before serving. (Add one minute of boiling for every one thousand feet you are above sea level.)

Once you have brought food to a safe temperature by cooking, keep it hot (over 140°F) until it is eaten. This helps prevent any bacteria or spores that chanced to survive the cooking (or were newly introduced into the food by some accident after cooking) from having a chance to multiply in it. For the same reason, you should cool foods to below 40°F quickly. Otherwise, the food spends a dangerously long time passing through the risky temperature zones in which microbes multiply (between 40° and 140°F). And you should keep foods cold (40°F or less) that are supposed to be cold. Be sure to reheat leftovers thoroughly before serving them. Liquids or wet foods should be brought to a rolling boil. Bring other foods, including leftover meats and poultry, to at least 165°F.

The USDA recommends that you always use a meat thermometer to be sure that your food has actually reached and been maintained at the recommended safe temperatures. (A meat thermometer will sometimes work for other kinds of foods.) The cooking temperatures to which you should heat foods in the table below are recommended by the USDA.

Using Thermometers for Food Effectively. Insert the thermometer in the places that are likely to get hot last. The leg of your turkey may register a high temperature even when the meat deep in the breast is still uncooked or when the stuffing is not nearly cooked enough for safety.

In poultry, insert the meat thermometer into the inner thigh area near the breast, not touching bone.

Test the stuffing separately, and test it twice—once just before the stand time and once at its end. The stand time is the time that you leave your bird to stand at room temperature immediately after cooking and just before serving. The temperature of the stuffing will probably continue to rise throughout the stand time.

In meats, make sure the thermometer is in the thickest part and away from bone, fat, and gristle.

Insert the thermometer in the thickest part of casseroles and egg dishes, but make sure it does not touch the bottom.

In thin items such as chops or groundbeef patties, put the thermometer in sideways.2

You may use either of two main types of meat thermometers, but be sure that you use a meat thermometer and not a candy thermometer or some other kind. One type of meat thermometer is oven proof. You insert this type in the food before you put it in theoven and leave it there during cooking until it shows that a safe temperature has been reached and the food is done. The other is a quick-read type. You cannot leave it in the food. If your food is in the oven, pull out the oven shelf and insert the quick-read meat thermometer in the proper place in the food for a good test reading: about two inches into the thickest part of the food not touching the bone. It registers in about fifteen seconds. Be sure to wash any thermometer with hot, sudsy water after use and before reinserting to test temperature again. Washing ensures that any harmful bacteria present in the food before it achieves a safe temperature are not reintroduced later by the thermometer itself.

Some poultry comes with pop-up thermometers already nserted. They are accurate if properly placed, but it is wise to use another thermometer to test the bird in a few other places just to be sure. You can also buy your own pop-up thermometers.

Test microwaved food for safe temperatures with a thermometer too; be sure to test in several places. (There are thermometers specially designed for use in microwaves.) Microwave cooking presents special risks because it leaves cold spots in the food in which microorganisms can survive. To ensure that all parts of the food have warmed to safe temperatures, cover the food with a lid or vented plastic wrap. This makes steam build up underneath and helps get all parts of the food warm. Remove the dish and stir thoroughly a couple of times during cooking, and turn the dish in the microwave, or move it now and then, so that different parts of it warm. If a microwaving recipe calls for standing time, obey the recipe! Cooking goes on during this period from heat already absorbed by the food.

Some Guidelines for Food Safety

Cooking Red Meats and Hamburgers Safely. Use your eyes when you cook. Red meats should be cooked at least until they turn grayish or brown, without any pink or red flesh or juices, inside or out. Pork is usually well cooked when the juices run clear. Because of deadly outbreaks of illness caused by E. coli O157:H7 in undercooked hamburgers, the USDA recommends that no one—especially children, the elderly, and immunosuppressed or otherwise vulnerable people—eat rare or medium-rare hamburger or any other dishes that include raw, rare, or pink beef. Moreover, because of some evidence indicating that ground beef can be unsafe even when it is not pink, the USDA strongly urges everyone to use a meat thermometer to test the doneness of hamburgers. The desirable temperature is 160°F inside the thickest part of the patty.

Ground meats, such as hamburger, are more dangerous than others because grinding spreads any dangerous microbes throughout the meat. Thus a hamburger patty is more likely to have E. coli in its pink middle than a steak, which is likely to harbor bacteria on its outside where they are more readily reached and killed by the heat of cooking. But rare meat of any kind poses risks. It takes very few E. coli O157:H7 to cause illness, and the illness can be deadly. Children, immunocompromised people, the elderly, pregnant women, and sick people of any description are particularly vulnerable to serious harm from rare and undercooked meats.

Cooking Poultry Safely. Pathogens such as Salmonella enteriditis, Campylobacter jejuni, Staphylococcus aureus, and Listeria monocytogenes are estimated to be present in a substantial percentage of all poultry sold for food in this country. The Centers for Disease Control documented 39,027 cases of salmonellosis in 1996 and estimates that the number of unreported cases each year runs to the hundreds of thousands or higher.

Cook poultry at least to the USDA-recommended temperatures. Poultry is generally cooked safely when the juices run clear, but you cannot be sure unless you test with a meat thermometer. The USDA recommends that you cook stuffing separately because of the frequency with which people fail to get it hot enough inside the bird and suffer illness as a result. If you really want to cook stuffing in the bird, however, do not place the stuffing inside until immediately before cooking, and do not buy prestuffed turkeys. When you have tested both the bird and the stuffing with a meat thermometer to make sure each has reached a safe temperature (in the manner recommended on page 165), remove the stuffing immediately and place it in a separate serving bowl. Never cook a stuffed bird in the microwave. Because the microwave heats foods unevenly, you cannot be sure that all parts will reach a safe temperature. You can address questions about safe cooking techniques for poultry and stuffing to the USDA Meat and Poultry Hotline at 1-800-535-4555 (or 447-3333 if you’re calling from Washington, D.C.). Or write to your local cooperative extension service.

Cooking Eggs Safely. Given many people’s taste for lightly cooked egg dishes, perhaps even more important than the increase in contamination of poultry is the contamination of eggs with salmonella. Strains of this bacterium infect hens’ ovaries and get into the egg in its shell. The USDA urges us to exercise greater caution in our use of eggs. Everyone can eat hard-cooked eggs, as hardcooking them, by boiling or frying, kills salmonella bacteria. All of us, but especially all vulnerable people (the very young and old, sick people, immunosuppressed people) should avoid eating any eggs with soft or runny yolks—soft-boiled, over light, sunny-side up, or prepared in similar styles. The USDA recommends that healthy adults who are determined to eat eggs that are not completely firm follow the cooking time guidelines below to reduce risk. Doing so is intended to partly hard-cook the yolk all around its outside and get the middle hot and thickened but not hard.

Fried eggs: cook 2 to 3 minutes on each side; 4 minutes in a covered pan.

Scrambled eggs: cook until firm throughout.

Poached eggs: cook 5 minutes over boiling water.

Soft-cooked eggs: Cook 7 minutes in the shell in boiling water.

All foods made with raw eggs, and recipes for foods containing raw eggs, should be avoided: meringue, eggnog, homemade mayonnaise, homemade ice cream, Caesar salad, chilled chocolate mousse, or béarnaise or hollandaise sauce. (Many of these foods can be made using pasteurized egg products or substitutes. To find revised recipes, contact your local cooperative extension service or find an up-to-date cookbook that offers recipes that rely on pasteurized eggs or other substitutes for fresh eggs.) Do not taste egg-containing foods before they are cooked—cookie dough, raw egg noodles, cake batter, various pie fillings, or pudding. It is especially hard to deny tastes to your children when you remember happily licking the spoon or bowl in your own childhood and suffering no harm from it, but it is necessary to do so. Refrigerate cooked eggs and foods containing them promptly when meals are over. Even hardcooked Easter eggs should not be left out of the refrigerator. If they have been unrefrigerated for more than two hours, throw them away. Hard-boiling an egg in the shell destroys much of the natural protection given by the shell. Thus, even though cooking kills bacteria in the egg at the time of cooking, it also renders the hard-boiled egg less resistant to future contamination than an uncooked one. Refrigerate hard-boiled eggs and use within a week.

Cooking Fish Safely. Fish is generally cooked when it flakes with a fork and no longer looks wet or rubbery inside. Eating raw fish or shellfish is playing Russian roulette. All fish and shellfish must be thoroughly cooked. Cooking shellfish just enough to open the shells is definitely insufficient to destroy many dangerous types of microorganisms, and eating such shellfish is a common cause of food poisoning. Raw or undercooked oysters and clams—even when fresh and when taken from “clean” water—may harbor any of several dangerous microorganisms, such as Vibrio vulnificus, an emerging pathogen that is extremely dangerous to people with liver and immune disorders and other illnesses.

Buy Pasteurized Milk, Dairy Products, and Juices. Pasteurization is an indispensable heat treatment for many foods. Always buy pasteurized dairy products; never consume raw milk or cheese or other products made from raw milk. Always buy pasteurized juices and cider, too; especially avoid serving unpasteurized juices or cider to children or other vulnerable people. Serious outbreaks of illness have occurred from E. coli in unpasteurized apple juice and cider.

Two Basic Rules for Safely Serving Foods. The first rule of thumb recommended by food-safety experts is this: keep hot foods hot and cold foods cold. This means to keep hot foods at 140°F or higher and cold foods at 40°F or below. At a buffet, use heating devices to keep the hot dishes at temperatures of at least 140°F. Use ice to keep cold foods at temperatures of 40°F or lower. Put foods in the refrigerator or keep them heated on the stove until you are ready to serve them. Marinate foods in the refrigerator, not on the countertop.

The second rule for keeping food safe is the “two-hour rule.” Hot foods and cold foods that are left at temperatures lower than 140°F and higher than 40°F for more than two hours should be thrown away, no matter how heartbreaking this seems or how it hurts your budget. If the air temperature exceeds 90°F, throw away any food that stands out for one hour. Don’t taste foods to see if they still taste good. Much dangerous food tastes and looks good, and is still dangerous even if you recook it. Heat may not destroy toxins in food even though it destroys the bacteria that produced the toxins.

Cooling and Thawing Safely. As cooked food cools, say from 150° down to 35°F, it necessarily passes through temperatures between 40° and 140°F, the range most favorable to the growth of bacteria. Therefore, when you are ready to store food, you must try to cool it as quickly as possible, so that it spends a minimum of time in that dangerous zone. To achieve this, you are advised by the USDA to put foods in the refrigerator or freezer for cooling. Do not first let the stock or soup or roast cool on the stove or countertop. You are also advised to break food down into smaller portions for cooling and freezing, because even in the refrigerator or freezer large batches take too long to cool or freeze. Put leftovers in shallow, small containers. (Be sure that they do not leak or drip.) If you are refrigerating stuffing, take it out of the bird or roast and put it in a separate container to speed the cooling process.

You may object that putting things in the refrigerator or freezer when they are still hot temporarily warms the refrigerator or freezer and makes it run more. You are right, but this does not last long. The benefits of doing so definitely outweigh the costs. (To avoid heating up the refrigerator or freezer, however, I sometimes cool soups or stocks by cooking them down, then adding ice cubes until they again reach the proper volume.)

The USDA urges you not to thaw foods at room temperature, on the counter. If you thaw a frozen chicken on the countertop, the outside of the chicken reaches room temperature while the inside remains frozen. Salmonella and other microorganisms can begin multiplying in those outer portions even while the inside is too cold. Your safest bet is to thaw foods in the refrigerator. This ensures that no part of the food ever exceeds 40°F. When thawing foods in the refrigerator, put a plate under them so that juices do not drip onto other foods or onto shelves where they might contaminate other foods.

Refrigerator thawing takes foresight. It can take days to thaw a large chicken or turkey in the refrigerator, depending upon how deeply the bird was frozen and how large it is. Allow twenty-four hours for each five pounds of weight; for example, for a fifteen-pound bird, allow seventy-two hours, or three days. If you need to thaw something faster, the USDA recommends the cold-water method. Fully immerse the frozen bird, wrapped in leakproof plastic, in cold water. Allow thirty minutes per pound, and change the water every thirty minutes. This would produce thawing in the following time periods:

8-12 pounds . . . . . 4-6 hours

12-16 pounds . . . . . 6-8 hours

16-20 pounds . . . . . 8-10 hours

20-24 pounds . . . . . 10-12 hours

The fastest of all thawing methods is the microwave. When you do this, however, you must cook the bird immediately after thawing it. The time required varies not only with the size and nature of your food but with the power and make of your microwave. Refer to your manufacturer’s instruction booklet. My microwave will thaw a three-pound whole chicken in a little over twenty minutes; yours may be different. Of course microwave thawing may be impossible for large items such as turkeys. Moreover, you may find that microwave thawing negatively affects the texture, tenderness, or moistness of certain foods. In some cases, however, it is ideal—for example, when you want fast thawing of stocks and soups.

Avoiding Cross-Contamination

You would never lick a fork after you had speared raw chicken with it. But many people unthinkingly engage in kitchen practices just as dangerous as this. Cross-contamination is what happens when food pathogens in one food are transferred to another food. Although the food-safety experts tirelessly warn us against it, the classic route to illness from cross-contamination is still traveled hundreds of times each year: someone cuts up raw chicken, meat, or fish on a chopping board or plate or other surface, and then, without first washing and sanitizing the chopping surface, chops salad vegetables on it. The raw flesh leaves a pathogen on the chopping board, which is picked up on the lettuce or cucumbers and then eaten in a raw salad. No one gets sick from eating the flesh, since it is first cooked to a safe temperature, but the whole family becomes deathly ill from eating the apparently harmless salad. To avoid crosscontamination, you must be sure not to accidentally introduce pathogens into foods, especially foods that are to be prepared and stored in ways that will not kill bacteria or prevent them from multiplying.

Cross-contamination can happen in a hundred different ways. One food can drip contaminated drops onto another. One unsafe ingredient can contaminate an entire dish. A transfer can be effected through a spoon, a pot, or a chopping board. Your own hands all too often supply the route whereby bacteria travel from one food to another. Even the most experienced cook can benefit from reading through the rules set forth below.

Guidelines for Avoiding Cross-Contamination

Wash your hands for fifteen to twenty seconds in comfortably hot, sudsy water. Much foodborne illness is caused by a failure to exercise this basic rule of hygiene. If you wear plastic gloves, you still have to wash, in the same way, with the gloves on, because they pick up microorganisms too. Wash your hands especially carefully after using the toilet, changing a baby’s diaper, blowing your nose, or touching a pet, a cage, or the cat-litter box. Wash your hands before you cook anything. Not only that, continue to wash your hands throughout the cooking process, especially after you have handled anything raw or likely to harbor pathogens. This means washing your hands before and after you cut up raw poultry, fish, meat, or any other animal food. (Then wash and sanitize your chopping boards and implements too.) Wash your hands before and after handling raw fruits or vegetables. Wash your hands when you have finished handling one foodstuff and are going to work on another. Cover cuts, sores, or boils on your hands or face with a waterproof dressing or wear disposable plastic gloves.

Always touch food with your hands as little as possible. Use utensils instead. Be especially careful to avoid touching food if you have had a foodborne illness or any type of diarrheic illness.

Be careful about what you dry your hands on. Use either paper towels or a clean cloth towel, that is, one that has not previously been used.

Don’t sneeze or cough over or near food.

Never place other foods on a chopping board, plate, or other surface on which you have previously placed raw meat, poultry, fish, or eggs unless you first wash it thoroughly in hot sudsy water. For additional protection, sanitize the chopping board. (Instructions for sanitizing are given on page 173.) In fact, the experts recommend that you keep at least two chopping boards. Use one chopping board for fruits, vegetables, and bread, and keep one or more other chopping board only for meats, fish, and poultry. In any event, wash and, if you wish, sanitize any chopping board immediately after using it in the preparation of raw meat, poultry, or fish.

Wash any chopping board, plate, or other food-contact surface with hot, sudsy water after chopping fruits and vegetables on it, too, for these can also harbor pathogens, even though illness from such sources is less common. (Wash the produce too.) Always keep in mind that whatever touched the board will touch the next food on the board—unless you first wash or wash and sanitize.

After using knives or other utensils on food—especially raw meat, poultry, fish, or eggs—thoroughly wash them in hot sudsy water before using them on other foods. For additional protection, sanitize knives according to the instructions on page 173. Put plates or platters under foods that might drip in the refrigerator. Be extremely careful not to let raw fish, meat, or poultry liquids drip onto foods that will be eaten without cooking. Wrap foods in plastic wrap or put them in plastic bags to protect them.

Watch out for drips, splashes, and accidental mixings. Move things out of the way when you have to carry packages of raw meat, poultry, or fish, and try to carry them in leakproof packages or on plates. Keep raw meats, fish, poultry, and eggs well separated from cooked foods and from foods that are to be eaten raw, such as fruits and vegetables.

When liquid from meat, poultry, or fish spills onto your counter or into your sink, immediately wipe it up and wash the counter or sink with hot, sudsy water.

Immediately wash with hot, sudsy water or place in the dishwasher any utensil, plate, or pot that has come into contact with raw meat, fish, eggs, or poultry. And never pull a utensil out of the dishwasher, rinse it under the tap, and use it. The utensil may have touched something dangerous. Rinsing under the tap will not get it clean enough for safety.

Keep the refrigerator and pantry shelves, drawers, and walls clean so that stored food does not become contaminated from food stored there earlier or from molds growing there.

Use different spoons to stir different bowls and pots. If you used a spoon to stir a dish when it was raw or not adequately cooked, thoroughly wash it before you use it to stir the same dish later. Otherwise, microbes left on the spoon by the food in its raw state will reinfect it.

Every time you taste food you are preparing, use a clean spoon or fork. Do not put a utensil that has gone into your mouth into food that will be eaten by others. Germs in your mouth may be deposited into the food by means of the spoon or fork. Likewise, never use your own eating utensils to serve or taste food in a serving bowl at the table.

Serve foods only with perfectly clean plates, bowls, pots, and utensils. Never serve food on a plate that has been touched by raw meat, poultry, eggs, or fish.

If a recipe calls for you to baste food with its marinade, reserve some for this purpose before you put the food in the marinade. Make sure that the marinade cooked with the food comes to a rolling boil. Marinades that will not immediately be cooked with the food that was marinated should be discarded. If there were any dangerous bacteria on your raw chicken or meat or fish, they will have contaminated the marinade too.

Never put leftover foods or condiments back into the jars or cartons out of which they originally came. That is, do not pour milk or cream from the table pitcher back into the carton in the refrigerator; do not put mayonnaise back into the mayonnaise jar; do not put leftover chicken or tuna salad back in the plastic container in the refrigerator from which you served it. This way you avoid contaminating the original source if the part that was taken out has somehow become contaminated.

Do not mix leftovers with fresh foods unless you are going to eat the mixture immediately, and make sure the leftovers are fresh enough to eat. (And preheat cooled leftovers to at least 165°F before eating them.) Remember that you shorten the storage life of any food when you mix it with food that is about to expire.

Store fruits and vegetables in their own bags and places. Store newly bought ones separate from old ones; do not put the old head of lettuce into the bag with the new one.

Keep pets out of food preparation areas, and off tables and countertops.

Washing Your Foods

Thoroughly Wash Fruits and Vegetables. Do this just before using them, not before putting them in the refrigerator. Even if you are going to peel the produce, wash it thoroughly before you peel it because otherwise your knife or peeler or fingers could pick up microorganisms and carry them through to contaminate the underlying flesh of the produce. Washing helps remove not only dirt, but microorganisms and any traces of pesticides. Food scientists say that washing probably decreases the risk of getting sick but does not eliminate it, particularly because bacteria may adhere tightly. Still, the experts agree: wash produce thoroughly, even if you plan to peel it.

Before washing, remove all outer leaves. Wash hard-skinned produce such as cucumbers, apples, or eggplant by scrubbing hard and thoroughly, under a hard stream of running cold water, with no soap, until all visible soil is removed. The force of the running water, like the scrubbing, helps carry off microorganisms as well as dirt. If there is no visible soil, wash or scrub hard under running water anyway. Use a clean vegetable brush for scrubbing, especially on root vegetables such as carrots and potatoes. Bacteria are especially likely to be numerous in bits of soil that adhere to vegetables. Even if you see no soil on them, root vegetables are still more likely to harbor bacteria from the soil. Vegetables fertilized with manure are particularly suspect.

Of course, you cannot scrub or rub softskinned produce such as berries, mushrooms, lettuce, or greens without macerating them. The best technique for washing these is to wash them in a stream of water as hardrunning as it can be without ripping or bruising the produce. Gently rub off the dirt or soil under the stream. You can put berries and similar items into a sieve or colander, running the water over them as you gently bounce or turn them. Wash all vegetables for a long time. A few seconds won’t do.

You may have seen newspaper or magazine articles telling you to wash produce with soap, but the FDA and the USDA do not recommend using soap; its residues might remain on or get absorbed into the food. (Some authorities say soap may also break down the skin of the produce, rendering it more susceptible to bacterial invasion.)

Washing helps reduce any pesticide residues on foods, as does peeling away skins and rinds and tearing off outer leaves.4 In peeling, of course, you sacrifice the nutrients and fiber in these portions of the foods.

Wash Lids of Cans. Use a little hot, sudsy water and dry with a clean towel or paper towel. Be sure to wash and dry thoroughly the crack at the circumference of the lid where dirt tends to resist washing out. Don’t forget that the can has been handled by strangers and perhaps has sat in warehouses, in storerooms, and on shelves for days, weeks, or months. It has collected dust and, perhaps, insect or rodent droppings, hairs, pesticides, cleaning substances, or heaven knows what. If you do not wash it, the liquid inside the can will wash the dirt on the lid into the contents when you press down while opening.


The USDA believes that using your dishwasher or washing your dishes with hot, sudsy water ordinarily gives you all the protection you need against pathogens. Sanitizing offers added protection in certain circumstances. Effective sanitizing requires a germicidal agent that kills a broad spectrum of microorganisms; for surfaces and objects that are going to touch food, you need one that will be safe around food, even without being rinsed off. For home use on utensils and surfaces that will touch food, the USDA and the FDA recommend regular household chlorine bleach (a 5.25 percent solution, approximately, of sodium hypochlorite). It kills a broad spectrum of bacteria, viruses, and molds; it is fast, highly effective, and cheap; and it quickly breaks down into harmless components. When you are sanitizing non-food-contact surfaces, such as ordinary countertops or tabletops on which you do not place food directly, you can use any commercial sanitizing product you like. Look for an EPA registration number.


Wash your hands!

Cook foods hot enough and long enough.

Keep hot foods hot (140°F or higher) and cold foods cold (40°F or lower) while waiting to serve them or storing them. Do not eat foods that have been kept at improper holding temperatures for two hours or more (or for one hour in temperatures of 90°F or higher).

Refrigerate leftovers quickly.

Chill or freeze food rapidly in small quantities. Reheat leftovers to 165°F.

Thaw foods in the refrigerator, in ice water, or in the microwave, not on a countertop or at room temperature.

Avoid cross-contamination.

Wash vegetables and fruits carefully.

Keep fingers out of food. As much as possible, avoid handling food; use utensils.

In addition to the details given below, further information on sanitizing and disinfecting can be found in chapter 30, “Peaceful Coexistence with Microbes.” Keep in mind that the sanitizing and disinfecting methods ordinarily recommended for the kitchen are backup measures, intended to reinforce other sound habits, not replace them. They do not produce germfree surfaces and objects, but, properly used in conjunction with those habits, help reduce the numbers of bacteria, including potentially harmful ones, so that you have an increased margin of safety. Those who wish to target specific pathogens or who are dealing with situations that pose serious health threats should seek medical advice or the advice of public health authorities in their own communities.

How to Sanitize Food-Contact Surfaces.

A basic sanitizing method for all hard foodcontact surfaces and objects in your kitchen, wooden and others, is this:

First, wash the surface carefully with hot, soapy water, making sure that no soil or food particles remain; then rinse thoroughly with plain, clean water.

Second, if possible, immerse it in a sanitizing solution made up of one teaspoon of household chlorine bleach and one quart of water. Leave it in the solution for a few minutes. If it is something that cannot be immersed—for example, a countertop—then flood it with the sanitizing solution, keeping it wet for a few minutes.

Third, take it out of the sanitizing solution and let it air dry, or pat it dry with clean paper towels. Do not rinse!

In this way you can sanitize chopping boards, plates, utensils, sinks, countertops, and any other hard objects or surfaces that have come in contact with raw meat, poultry, fish, eggs, or other foods likely to harbor hazardous microorganisms. It is not a bad idea to sanitize all chopping boards now and then, even if you have not used them for especially hazardous raw foods, even those labeled antimicrobial (see page 175).

Why We Do It This Way. When you are sanitizing, cleaning comes first. Before sanitizing food-contact surfaces or objects, you must always first thoroughly wash them with sudsy, hot water. Otherwise, the sanitizing may be ineffective. Remarkably more bacteria can live on a tiny crumb of meat or in a drop of sauce than on any wet or unsanitized countertop; the more food is present, the more bacteria. Even more important, organic matter—food particles, the remnants of spills, crumbs of any sort—can inactivate some antimicrobial products and solutions, including chlorine bleach, preventing them from doing their germ-killing job. See chapter 30, pages 420 and 431-35. This is why the first and most important line of defense against pathogens in the kitchen is ordinary cleaning—getting rid of crumbs, bits of food, spills, and sticky or oily surfaces. Use some muscle power when you clean; scrub hard, and spray with a strong stream of water. Notice also that you should not rinse after sanitizing food-contact surfaces; anything that touches the surface after sanitizing has the potential to recontaminate it. Thus any products to be used for sanitizing food-contact surfaces should not leave toxic residues behind.

Alternative methods are feasible. For example, the 1999 Food Code (a set of model regulations for food services, without the force of law)5 permits sanitizing food-contact surfaces and utensils by immersion in water that is maintained at 171°F or higher for thirty seconds.6 (If you want to do this, you should first thoroughly wash the items in hot, sudsy water and rinse them; after immersion in the hot water, the items should be allowed to air-dry.)

Some people just put their chopping boards in the dishwasher after using them, and this is probably effective. (See “Sanitizing in the Dishwasher?” below.) However, it is often impractical—for example, when you want to use a chopping board again right away, when it is not dishwasher-safe, or if you do not know how hot your dishwasher gets.

Microwave sanitizing, too, is theoretically possible, and you may see recommendations in newspapers and magazines to use this method. To me it seems unwise. There are no reliable guidelines for the home use of this technique, and there are grave uncertainties involved. For one, microwaves differ from one another and do not all produce the same results. For another, various studies have shown that microwaving works with some objects but not others. Plastic chopping boards, for example, will not get hot enough to be sanitized. Microwaves’ spotty heating can be a problem too. Until the food-safety experts announce that they think either of these methods is a good idea for the home, and explain just how dishwasher or microwave sanitizing might effectively be done in the home for different sorts of objects and surfaces, the bleach method for sanitizing foodcontact surfaces continues to be a choice that is simple and highly effective.

Which Surfaces Should Your Food Touch?

Food belongs on properly maintained and sanitized chopping boards, pastry boards, properly washed and dried pots, pans, dishes, and utensils. Some countertops are designed to be used for food preparation. However, if you want to chop and prepare foods on your countertop, your home should follow rules designed to keep it scrupulously clean and safe. If you cut up chicken on your countertop, you should sanitize the countertop and follow the same rules regarding cross-contamination, with scrupulous care, as you do for chopping boards. You must also ensure that none of the following items are ever put on your countertop: unwashed hands, newspapers and magazines, bags of groceries, toys, bookbags, knapsacks, purses, or briefcases. These objects may have touched the floor, the ground, the sidewalk, or the grocery store checkout counter. If you do not set foods on countertops, this rigor is not necessary and you need to do much less sanitizing. In my home, I find that it is much less trouble to use a clean plate or chopping board than to have to sanitize the counter before using it and worry about who did what on the countertop while I was out of the room. Do not forget that if the kitchen rules are to work, everyone in the household must follow them.

A Note on Chopping Boards. Food-safety experts recommend that you keep two chopping boards: one for raw fish, meat, and poultry, the other for produce and everything else. This in itself goes far to prevent cross-contamination, especially contamination of foods to be eaten raw, by dangerous bacteria from raw fish, meat, or poultry. The debate on whether plastic or wooden chopping boards are better is now regarded as settled in favor of plastic ones. Glass cutting surfaces, too, are recommended over wood for raw meat, fish, and poultry. This is the USDA’s latest and best word, although it regards wood cutting boards that are used exclusively for raw meat and poultry as acceptable. Wood chopping boards can conceal bacteria in their grooves and pores.7 Throw away any chopping board—no matter what it is made of—as soon as it shows grooves or nicks, because these can hold bacteria and food particles and render the board difficult to clean. To keep all cutting boards clean, the USDA recommends washing them with hot, sudsy water after each use; then rinse and air-dry or pat dry with fresh paper towels. Nonporous acrylic, plastic, or glass boards and solid wood boards can be washed in an automatic dishwasher (laminated boards may crack and split). (To sanitize chopping boards, follow the instructions on page 173.) By the way, although hard, nonporous surfaces of plastic make the most sanitary chopping boards, they are harder on your knives. They will dull them more rapidly than wood, so be prepared to sharpen as necessary.

If you have chopping boards that are labelled “antibacterial” or “antimicrobial,” always wash and sanitize them in the same way and on the same occasions as you would any others. They are not intended to be used to replace or substitute for ordinary safe food practices. (The real nature and life span of their antimicrobial efficacies is currently unclear, but you can be sure that if you have gotten raw chicken juices contaminated with pathogens on your chopping board, its antimicrobial action will not render them harmless.)

Sanitizing Non-Food-Contact Surfaces and Objects

Hard Surfaces and Objects. Hard surfaces and objects that do not come into contact with food—sinks, countertops, refrigerator drip trays—can be sanitized in the same way as hard food contact surfaces. See page 173.

The Drain and Disposal. Sanitize your kitchen sink drain, connecting pipe, and garbage disposal once or twice a week following your final kitchen cleanup in the evening. This will help control odors as well as keep your kitchen safe. Food particles trapped in this moist environment provide a felicitous habitat for microorganisms, which may grow there in astonishingly high numbers. Contaminated drains are associated with increased risks of acquiring a foodborne illness. To sanitize your drain, connecting pipe, and garbage disposal, the FDA recommends that you make a sanitizing solution of one teaspoon of regular chlorine bleach in one quart of water and pour it down the drain. Or you can use any commercial sanitizing agent according to the directions.

Cloth. Use towels, cloths, and rags prodigally in your kitchen. Keep plenty around, and when they get even a little damp or soiled, get fresh ones. When they are damp and soiled, they grow microbial armies. If you wipe down a countertop with a bacteria-laden towel or cloth, you spread bacteria everywhere. If you go through several of each every day, that’s good. They are easy to launder. Ordinary laundering of dish towels, hand towels, dishcloths, aprons, potholders, cheesecloths, pastry cloths, dishrags, and other kitchen cloths will generally make them safe. Washing them with chlorine bleach sanitizes them, and like my mother and grandmothers before me, I do this automatically with all kitchen linens. Some people do not like to use chlorine bleach so often, but they might wish to do so on occasion—say when they have some particular reason to be concerned (or when the linens are beginning to look dingy). To give yourself this valuable option, never buy cloth for the kitchen that you cannot bleach. (To sanitize kitchen towels, rags, and cloths of all sorts, see chapter 27, “Sanitizing the Laundry.”)

Brushes, Pot Scratchers. Cleaning implements such as brushes and various types of abrasive scratchers should be washed entirely free of food particles with hot, sudsy water every time you use them. Squeeze out the excess water until they are as dry as possible. If necessary, you can sanitize them as follows: Immerse brushes and pot scratchers in a solution of one tablespoon regular chlorine bleach per gallon of water, and let soak for five to ten minutes. Drain and let air-dry.

Odors indicate that bacteria are growing. The absence of odors, however, is no guarantee of safety, not even in so-called anti-bacterial cleaning implements. Wash all implements frequently in hot, soapy water, being careful to remove food particles that adhere to them, and do not keep them too long.

Sponges and Dishcloths. I am no fan of sponges for cleaning in the home. Sponges are havens for bacteria; tiny food particles get deep inside, and sponges stay wet for long periods of time. The bacteria that survive deep inside sponges are smeared around your kitchen every time you use them. Do not use sponges to clean up after raw meat, poultry, eggs, or fish. If you choose to use them for such a task, you must discard or sanitize them afterward or they will simply spread contamination to everything they touch.8 Even when you are not aware of wiping up any particularly hazardous material with your sponges, you should occasionally sanitize them anyway. Studies show that typically they hold large numbers of potentially hazardous microorganisms.

When sanitizing sponges, first get the sponges quite clean of food and other soil. (Remember that sanitizing agents do not work so well in the presence of organic matter.) Wash the sponges thoroughly by hand with hot, soapy water, repeatedly squeezing them so as to get out food particles and all organic matter, rinse them thoroughly. Then mix a gallon of water with ¾ cup regular chlorine bleach in the sink. Soak sponges in the bleach solution for five minutes. Rinse and air-dry. You can sanitize dishcloths this way, too. Dry them in the sun or in the dryer.

What was said about odors in brushes and pot scratchers, above, also goes for dishcloths and sponges. It means bacteria are growing, but if a cloth or sponge lacks odors, this is no guarantee of safety.9 Launder your dishcloths frequently; use one or more fresh ones each time you do a kitchen cleanup or wash the dishes. Wash sponges often with hot, soapy water, and do not keep them long.

Sanitizing in the Dishwasher? If you were running a food-serving establishment and wanted to sanitize dishes and utensils in the dishwasher, the 1999 Food Code would require that your machine first wash them with proper detergents or other cleaning chemicals, using a wash-water temperature of 150° to 165°F, depending upon the type of machine. Then it would require that the machine do a sanitizing hot-water rinse, either by immersion for thirty seconds in water IyI0F or hotter, or mechanically, usually at a temperature of not less than 180°F. By comparison, my dishwasher is designed to wash at 140°F and “sani-rinse” at 160°F.

Many of us would not be able to comply with these regulations at home because our machines don’t get hot enough. Some dishwashers get only as hot as the tap water, which is usually around 140°F or even much lower in many homes. Self-heating dishwashers may or may not get hotter than that; how hot even they get may depend upon the temperature of the tap water they receive. Few of us know how hot our machines are supposed to get, let alone whether they actually get that hot. Still, even if your dishwasher, like mine, does not heat its water as hot as 180°F, it probably gets pretty hot, and once your dishes have been washed and dried inside it they are likely to be quite safe for use, given the potent combination of heat, strong detergent, and drying they have been subjected to. Moreover, hard, nonporous objects such as utensils and dishes, when freed of soil, subjected to a bath of strong detergent in good hot water, and thoroughly dried, are terribly uncongenial homes for bacteria. We do not really need to worry much about our dishes and utensils when they have been washed and dried in an ordinary, dishwasher.

I would worry, however, about relying on a dishwasher to clean or sanitize things that a dishwasher is not designed for. I was surprised to learn that several of my friends had begun to follow recommendations, given on television and published in newspapers and magazines, to “sanitize” kitchen cloths and wiping rags, sponges, and similar soft and porous materials in the dishwasher. In my opinion, this is a dubious proposition. Dishwashers are not designed to clean soft, spongy objects. The objects they are designed for are hard and do not hold water or food particles. Sponges and cloths are left sopping by a dishwasher, for unlike clothes washers, dishwashers have no spin cycle. Moreover, unless you wash these soft things thoroughly before you put them in the dishwasher, they may remain full of food particles, for a dishwasher does nothing that will remove them. Even if you got all the food off them before putting them in the machine, why wouldn’t food flying around inside become reimbedded? If a germ or two manages to live through the dishwashing cycle (maybe it did not get hot enough long enough or maybe it was a heroic bacterium), it will find itself in microbe heaven—a warm, protected environment with plenty of food and drink and not much competition. And if you then leave everything in the dishwasher overnight, the microbes will have plenty of time to multiply themselves a few million times. Or suppose that all the germs are actually killed but your sponges and rags still contain food debris. The minute you take them out of the dishwasher, they are going to come into contact with whatever microorganisms are hanging around in the vicinity and provide them with a lot of sopping wet food.

Pot scratchers, vegetable brushes, and various other cleaning utensils also tend to trap food particles. Because of such doubts, I prefer washing by hand and then sanitizing pot scratchers, abrasive pads, and sponges in a bleach solution.

Guide to Common Food Pathogens

Food Molds and Mycotoxins

Molds that grow on food sometimes produce toxic substances called mycotoxins. These are dangerous in varying degrees, depending on their type. Aspergillus flavus, a food mold that commonly attacks corn and peanuts and to a lesser extent barley, wheat, and other foods, produces a group of mycotoxins, called aflatoxins, that are extremely dangerous. Acute symptoms of aflatoxicosis can arise about three weeks after eating moldy grains. But it is believed that longterm, low-level ingestion is dangerous too. Aflatoxins are thought to be carcinogenic. Indeed, they are among the most carcinogenic substances known to exist for rats, but it is still not clear whether or to what extent they may be human carcinogens. A link with liver cancer is suspected. Their other effects in humans, aside from acute toxicity, are also unclear. Among other things, it is believed that they may worsen cirrhosis of the liver and Reye’s syndrome and may weaken the immune system. Other mycotoxins can also cause acute poisoning and have been implicated in the development of various types of cancer (of the esophagus, stomach, kidney, liver), infertility, liver and kidney disease, and other ailments.

Disease attributable to consumption of mycotoxins is believed to be quite low in the United States as compared with other countries, particularly those with warm, humid climates where people are more likely to consume moldy grains and other moldy foods than they are here. Although much remains to be learned about mycotoxins, no one doubts that they pose health dangers, that the dangers increase in proportion to their quantities in the diet, and that their presence in food should be reduced or eliminated.


A soft or liquid food that shows any sign of mold—even the tiniest speck—must be discarded entirely. Molds can put out tendrils that you will not see, tendrils that can penetrate far into soft or liquid foods, and the toxins disperse throughout. Foods counting as soft include jams and jellies, syrups, apple juice, bread, pies, cakes and other baked goods, soft cheese such as Brie or American cheese or other soft yellow kinds, sour cream, yogurt, cottage cheese, flour, cake, peanut butter, hot dogs, bacon, meat pies, opened canned ham, sliced deli and luncheon meats, cucumbers, tomatoes, spinach, lettuce, kale and other leafy vegetables, corn (including corn on the cob) bananas, peaches, melon, all softer fruits, nuts, whole grains, and rice.

With a hard food, such as a block of cheese or a hard salami, you can sometimes cut the mold off, but you must cut away at least one inch extra as a safety margin. (Some authorities say one and one-half inches.) This often means, practically speaking, that you must throw away the whole chunk—for example, if a block of cheese is only an inch thick to begin with, or if it is two inches thick and has molded on both top and bottom. Foods that are hard enough to consider trimming in this fashion include: hard cheeses (Swiss, Cheddar), hard fruits (apples, pears), and hard vegetables (potatoes, turnips, parsnips, carrots, heads of cabbage, cauliflower, brussels sprouts, broccoli, bell peppers).

Molds can grow on just about any food: grain, flour, bread, cereal, jam, fruit juice, meat, nuts, leftovers. When moldy foods look or taste or smell bad, as they often do, people will throw them away. But sometimes there are no off-putting sights or tastes or smells connected with the contaminated food. Apple juice is often found to contain low levels of mycotoxins that no one can taste. A piece of slightly moldy peanut ground up in the peanut butter will never be noticed. And mycotoxins may be present in foods that have never been moldy. For example, if cows are fed moldy food, their milk and the dairy products made from it may contain aflatoxins. Government regulation is necessary to protect us from dangers like these. At home we must protect ourselves.

To protect against ingestion of mycotoxins at home, it is important to throw out food that has become moldy and to examine all stored foods carefully to be sure that mold has not begun to grow. Even a spot of mold is a call for action. Do not sniff moldy foods. Their spores can induce respiratory illnesses. If you find any mold at all in a box of cereal, cake mix, flour, or other grain food, throw out the entire box. Never eat a moldy or shriveled peanut. You will have less waste if you avoid buying more food than you can use before it goes moldy. Sometimes you can save part of a food that has gone moldy. Very often you cannot.

Mycotoxins are not readily destroyed by freezing or heating. Thus cooking will not make contaminated foods safe. (From 20 to 80 percent may survive cooking.) Preservatives, therefore, are relied on. The growth of food molds is inhibited by a number of food additives, including sodium bisulfite, sorbates, propionate, and nitrates, as well as by a number of natural substances in foods such as peppers of all types, mustard, cinnamon, and cloves. Bread that has not been treated with preservatives molds readily and becomes tainted with mycotoxins, especially in warm weather. (The condition called ergotism or St. Anthony’s fire, common in medieval Europe, was caused by a mycotoxin produced by a mold that grew in rye bread. Aflatoxins may also be produced by bread molds.) If you buy bread without preservatives, it is best to freeze it and thaw it in the microwave as you need it.

Molds are considerably less inhibited by salt and sugar than are bacteria and, unlike most bacteria, grow well in acid media. Acids may be consumed by molds. Thus moldy foods sometimes also become less acidic and then also become bacterially contaminated.


Bacillus cereus. Bacillus cereus, which occurs widely in nature, can be the cause of a short illness lasting up to a day. There are two strains. In one strain, which causes a diarrheal illness that lasts for about a day (with onset about eight to sixteen hours after consumption), the bacterium produces a heatlabile toxin; in the other, which causes an emetic illness also lasting about a day (onset in one to six hours), it produces a heat-stable toxin. (It is unclear whether the heat-labile toxin is produced in the food or the gut, however.) B. cereus, a problem in food services that hold food for long periods before serving, tends to contaminate plant foods such as cereals, corn or cornstarch, flour, rice, fried rice (so commonly the case that some sources refer to illness caused by B. cereus as the “Chinese restaurant syndrome”), baking products, potatoes, and cold soups. But sometimes animal foods, cooked vegetables, ice cream and milk, and tapioca and other puddings are the source. The cause is usually food left in the danger-zone temperatures too long—for example, by cooling too slowly. This bacterium forms spores—hard, protective shells. (See page 164.)

Campylobacter jejuni. This bacterium is a potential contaminant of many foods of animal origin, including unpasteurized milk and cheeses and chicken. It is readily killed by heat, acid, salt, and dryness, so ordinary food-safety practices should be sufficient to guard against it. Yet it has in recent years emerged as a major cause of diarrhea in the United States and the rest of the world as well, causing more cases of illness than salmonella. This is because it is so widely present in food, and ingestion of a very small number of the bacteria can result in infection. Onset is usually in three to five days, but this varies. Symptoms range from mild to severe, and, as always, it is more dangerous to more vulnerable people—the very old, the young, the immunosuppressed, and the sick. In moderately severe cases, symptoms may include malaise, fever, vomiting, or grossly bloody stools. In some cases, bacteremia, Reiter’s syndrome, Guillain-Barré syndrome, or urinary tract infection may result. It usually resolves in a few days to a week, but some cases are prolonged. Serious complications can result. It does not form spores. It causes illness through infection.

Clostridium botulinum. Botulism occurs rarely, but it is so dangerous that every household should understand it. The toxin produced by Clostridium botulinum is one of the most deadly substances known. It is a neurotoxin; it attacks the peripheral nervous system. There is an antitoxin, but it must be administered quickly. C. botulinum is widespread in nature, being found in the soil, water, on plants, and in animals and fish. It produces spores that are harmless unless they get into foods that supply the proper growing conditions, at which point they will germinate and produce the deadly toxin. These growing conditions include: a low-acid environment (C. botulinum grows only at a pH of 4.6 or higher), a temperature between 40° and 120°F, and the absence of oxygen.

Symptoms of botulism come on twelve to thirty-six hours after consumption of the toxin; they include weakness, dizziness, and sleepiness, followed by blurry or double vision, reduced salivation, hoarseness, and great thirst. Death is caused when the diaphragm is paralyzed, preventing breathing. The merest taste of the toxin can be deadly, so never taste food—especially anything canned at home—to see if it is spoiled. You can destroy the toxin (but not the spores!) by boiling the food for ten to fifteen minutes.

Low-acid canned goods that have been improperly processed, then stored and eaten without boiling are a typical source of botulism. Foods that have been associated with botulism are low-acid canned vegetables such as green beans, corn, and spinach; fish; fruits; condiments such as chili peppers or chili sauces; tomato relishes; and other foods that are not necessarily cooked before being eaten, such as cold soups, tuna fish, or mushrooms. The most common cause is improper home canning: either the heat and pressure applied are insufficient to kill the spores, or they are not applied for long enough. Having survived the canning process, the spores germinate in the airless environment of the stored cans or jars and produce toxins. Later someone eats the contents of the jar without boiling them for the requisite period. Because home canning is still a common cause of botulism in our day, experts recommend that you boil anything canned at home before eating it. Most outbreaks are caused by canned goods that contain food that is eaten without having been cooked.

Commercially canned foods are extremely safe and are the source of botulism extremely rarely. Still, now and then someone runs across a can of food that has gone bad. I once found an impressively bulging can of green chili peppers (imported) on my pantry shelf. I have a friend who once opened a can that had become so gassified inside that it shot liquid in the air. When you are buying canned goods or intending to eat home-canned foods, be alert for the following dangers:

Cans, containers, or lids that leak, bulge, or are damaged or cracked

Containers whose contents spurt or foam when opened

Food that smells or looks abnormal

In recent decades there have been several instances of botulism not attributable to canned goods. This was surprising, since the anaerobic conditions favorable to C. botulinum occur uncommonly. Each instance involved relatively new foods or methods of preparation combined with an abuse of temperatures. In one instance, baked potatoes were cooked in foil and then left at room temperature for several days. The foil apparently created an anaerobic environment around the potato. In another, a vacuumpacked salad served on an airplane flight in Europe was the cause. Here the oxygen was intentionally removed from the container so as to extend the life of the salad; then the salad was held at temperatures over 40°F. There have been outbreaks of botulism, including one in this country in which seven people died, from vacuum-packed smoked fish as well. The smoking and salting of the fish had been insufficient to destroy all C. botulinum, and it was left at dangerously warm temperatures. Still another case involved food oils to which flavorings such as garlic were added; the oil created an anaerobic environment around the garlic that, in turn, supplied bacteria. The oil was then stored at room temperature. (It is best not to make any flavored oils that are not intended for immediate use. But if you do, store them in the refrigerator.)

To learn the latest in safe home-canning practices, consult your local cooperative extension service.

Clostridium perfringens. This bacterium, like C. botulinum, is widespread in nature (in soil, dust, air, sewage, human and animal feces, and raw foods) and also produces spores. Meat and meat products (but not usually cured meats), gravies, and casseroles are common causes of food poisoning from C. perfringens. Also, like B. cereus, it tends to be a problem in food services that cook food and then hold it for long periods before it gets consumed. The cause is generally slow cooling, long storage at improper temperatures, or a failure to reheat to a proper temperature. Although it does not produce much toxin in foods, it does so in the intestines after being consumed. The diarrheal illness it causes develops in eight to twenty-four hours, after large numbers of the bacteria have been consumed, and lasts for about a day. It is relatively mild, except in vulnerable people, and does not last long (and probably often goes unreported).

Escherichia coli. This bacterium has received great attention in the press in recent years, and for good reason. Various strains of Escherichia coli commonly inhabit the intestinal tracts of people and animals where they usually do no harm. But it is now believed that pathogenic strains of E. coli are a common cause of the diarrhea travelers often acquire. Some types of E. coli cause a mild diarrhea; others produce severe diarrhea, possibly with blood or mucus in the stool, stomach pains, and vomiting. One strain of this ubiquitous bacterium, E. coli O157:H7, has been responsible for several outbreaks of virulent, often deadly illness. It may cause attacks of bloody diarrhea with cramps, mainly in adults. In children, it can produce hemolytic uremic syndrome, which is characterized by acute renal failure, hemolytic anemia (reduction in red blood cells), and thrombocytopaenia (reduction in blood platelets). This syndrome can result in kidney damage or even death. Children, the elderly, and sick and immunosuppressed people are especially vulnerable. E. coli O157:H7 has been contracted through ground meat that is undercooked, raw milk, soft cheeses (imported Brie in one outbreak), lettuce, unpasteurized apple juice and cider, and possibly chicken. E. coli survives freezing but is readily killed by heat. Hygienic practices are important, especially adequate washing of hands. Ordinary safe food practices—especially cooking ground meats to recommended safe temperatures and avoiding cross-contamination through cutting boards—provide good protection against it.

Listeria monocytogenes. This bacterium began to be regarded as a serious problem only in the 1980s. Water, soil, sewage, humans, and animals, including domestic pets, may carry it. Vegetables fertilized with manure may carry it; in one outbreak in Canada, coleslaw made from cabbage fertilized with manure was the source. An outbreak involving several hospitals in Boston in 1979 was traced to a raw-vegetable garnish made of celery, tomatoes, and lettuce. Chocolate milk, raw milk, soft cheeses, fish, meat (especially sausages and deli meats), and chicken have been contaminated with it. It is resistant to processing; it survives freezing, direct sunlight, and long-wave ultraviolet light. It is alleged to have survived pasteurization in one instance, but the literature is conflicting on this point. Like Yersinia enterocolitica (discussed below), it grows at refrigerated temperatures, but slowly. It shows growth in the range of 32° to 107.6°F, with greatest growth at 86°F to 95°F; at temperatures of 41°F or below it grows extremely slowly. It does not grow in moderately acidic media.

Although this bacterium is widespread in nature, infection is not correspondingly common, because people become ill only after ingesting high numbers of highly pathogenic strains. But it is of great concern because, depending on the type, it is so often fatal. The vulnerable groups—the very young, the very old, sick people, pregnant women, and the immunocompromised—are the most likely victims. The infection is especially dangerous during pregnancy, sometimes resulting in premature delivery of stillborn or ill infants. Listeria can cause a mild flulike illness, meningitis, septicemia, and other symptoms. In vulnerable people, it can also result in serious complications. The incubation period varies widely, from one to ninety days, with a few weeks being typical. The Centers for Disease Control estimates that in this country in one year there are 1,700 cases, that about 450 adults die of it, and that 100 fetal and newborn deaths are attributable to it. Protection is provided by keeping foods very cool in storage, and by following all ordinary safe food practices, including keeping foods out of the danger zone of temperatures and reheating adequately after cooling. It cannot hurt to wash vegetables thoroughly.

Salmonella. There are a couple of thousand types of salmonella that can cause food poisoning, and they are one of the most common causes of food poisoning in this country. Typhoid fever is one of the salmonella infections (caused by S. typhi). These bacteria grow in the intestinal tracts of people and animals and in raw meat. Likely carriers are food handlers, pets (dogs, cats, birds, turtles, fish, iguanas), rodents, and insects such as flies and cockroaches. Foods that have been most commonly involved in outbreaks include eggs and poultry and foods containing them (chicken and turkey and their stuffings or salads made of them, custards, cream cakes, eggnog, mayonnaise, and homemade ice cream) but also meat and meat-containing foods (pies, hash, sausages, chili) as well as milk and milk products—usually raw milk or cheese made from it.

Salmonella bacteria do not produce toxins; they cause an illness called salmonellosis by infecting the body. Symptoms arise within a day or less and usually last for one or two days; diarrhea, cramps, nausea, or vomiting are likely. Sometimes there are chills and fever, or mucus or blood in the stools. The very young and old, the sick, and immunosuppressed people are more vulnerable to this as to other infections. Some strains cause more serious infection than others, and some are resistant to antibiotics. Deaths from salmonella are uncommon except among the vulnerable groups, but symptoms can be severe, with a possibility of serious complications.

Food infected with salmonella does not look, taste, or smell different. The bacteria are readily killed by heat. To prevent infection, follow the general rules on food safety and safe cooking temperatures.

Shigella. Shigella, the bacterium that causes dysentery, comes from human beings. Associated with poor hygiene, it passes from person to person and through contaminated water, food, and flies. Food-service workers with poor hygiene can spread it to food, especially those foods that are much handled, such as potato salad, tuna salad, macaroni salad, chicken salad, and shrimp salad, and foods that are not kept at safe temperatures. Ordinary safe cooking and storage practices protect against it, and personal hygiene is important in preventing its spread. Although shigellosis is generally a more severe condition than salmonellosis, it is less common. There are between fifteen thousand and twenty thousand cases a year in the United States, most of them in children under the age of two. Symptoms include diarrhea (often bloody), abdominal pain, fever, and vomiting. Onset is from seven hours to seven days, and in most cases the illness lasts for a few days.

Staphylococcus aureus. This bacterium is a common cause of foodborne illness. It comes from people and animals. Introduced into food, it produces a dangerous toxin that is heat-stable, colorless, odorless, and tasteless. It grows well in protein foods and foods with high levels of salt or sugar: milk and milk products, custards, cream-filled bakery goods, puddings, meat, meat products such as sliced roast beef and ham, salads, and pies. Sliced ham and similar foods served at buffets and kept too long at room temperature are often the source of foodborne illness caused by this bacterium. Foods that have received a lot of handling and touching are much more likely to harbor the bacteria and thus its toxin. Illness caused by the toxin comes on quite rapidly after the contaminated food is eaten—within two or three hours—and is usually brief (one to two days). Few people die of it. The symptoms include nausea, vomiting, cramps, diarrhea, headache, weakness, chills, and fever. Personal hygiene is an important preventive measure—bathing and washing hands. Keep your hands away from your nose, mouth, hair, and skin infections. Don’t cough or sneeze on your food. Use utensils, not hands, when making food. Don’t dip your finger in food to taste it. If you have a cut or wound on your finger, wear plastic gloves. Follow all the general rules for food safety.

Vibrio cholerae. This bacterium is the cause of cholera, a disease characterized by diarrhea or bloody diarrhea, nausea, and vomiting. Dangerous dehydration can result, and cholera often causes death. Water that has been contaminated by human waste is the main source of cholera infections. Thus fish and shellfish, although not the only food sources, are the most common ones. There are still periodic epidemics of cholera, a dangerous infection, around the world, but it is uncommon in this country. Cooking destroys V. cholerae, but food must be cooked long enough. Cholera is one of the many dangers associated with eating undercooked or raw seafood.

Vibrio parahaemolyticus. This bacterium generally contaminates crabs, oysters, shrimp, lobsters, and other seafood, and causes infection when seafoods are eaten raw or undercooked or when raw or undercooked seafoods cross-contaminate cooked seafoods. (When you buy cooked shrimp or other fish at your market, pay attention to whether it is lying too close to uncooked fish or whether it is placed in such a way as to be dripped on when uncooked fish is removed from the case.) It is easily killed by ordinary cooking. Proper cooking—steaming just to open the shell is not sufficient—and careful refrigeration of seafood, in accordance with ordinary safe food practices, will help protect against it. The incubation period is usually between nine and twenty-five hours but can vary from two hours to four days. The symptoms include severe abdominal pain, nausea, headache, chills, and fever. Infection generally resolves within about three days but can last up to eight days.

Vibrio vulnificus. This bacterium, another emerging pathogen, is extremely dangerous to the vulnerable groups, particularly those with liver disease. It grows in water and causes human illness in undercooked and raw seafood, particularly oysters and clams. Adequate cooking kills it. Steaming shellfish just enough to open the shells is not sufficient; you need to boil oysters for three to five minutes after the shells open. Although V. vulnificus tends to infect only those with underlying illness or weakness of some sort, among this vulnerable group the death rate is frighteningly high, 40 to 60 percent. There is initially malaise, then chills and fever and great weakness. Sometimes, but not usually, there is vomiting and diarrhea. People with liver disease have a risk of death from this bacterium almost two hundred times greater than others. To protect against it, never eat raw oysters or other raw seafood, and cook them well. Carefully avoid cross-contamination; follow all other safe cooking rules.

Yersinia enterocolitica. Y. enterocolitica is found in animals and in water. Concern about infection by certain strains of this bacterium first arose in the 1970s, and its worldwide incidence has increased greatly from the late 1960s through the present. Pathogenic strains have contaminated chocolate milk, raw milk (goat’s and cow’s), powdered milk, and even pasteurized milk from one processing plant; tofu packed in contaminated water; and pork and other meat. Poultry, fish, game, vegetables (bean sprouts packed in contaminated water), and drinking water have also been sources. It will grow in refrigerated foods, but slowly. It is destroyed at temperatures over 140°F. Although it is only rarely fatal, it puts vulnerable people (the very young, old, and sick) at risk, and can result in serious complications. Illness from this bacterium is most commonly found in children under the age of seven. It has an incubation period of one to eleven days (usually two to five), and the illness can take five to fourteen days to run its course. It causes diarrhea and great abdominal pain. In severe cases, septicemia, meningitis, arthritis, or other serious illnesses may arise. Ordinary safe cooking practices and good personal hygiene are important protections.


Toxoplasma gondii, Sarcocystis, Giardia lamblia, Entamoeba histolytica, Cryptosporidium, and Cyclospora cayetanensis are all protozoa—one-celled animals—that can cause foodborne illness. Entamoeba is the cause of amoebic dysentery. Cryptosporidiosis amounts to a self-limited case of diarrhea in most healthy adults, causing serious problems only in immunosuppressed people and other vulnerable or weak people. Giardia lamblia causes diarrhea, cramps, and nausea. The incidence of foodborne illness caused by protozoa is quite low compared with that caused by bacteria. Nonetheless, Cryptosporidium appears to be on the increase. There was a massive outbreak in Milwaukee in 1993 when this microorganism got into the city water supply. And Cyclospora, a newly emerging pathogen that repeatedly made the news in the 1990s, was all but unheard of before this. In 1996, at least one thousand people in twenty states got sick from Cydospora infections. Its incubation period is about a week, after which it causes a severe diarrheic illness, with cramps. Serious weight loss is a common effect. Unlike many types of foodborne illness, however, it can last for weeks or even months. Both of these (like all foodborne illnesses) are dangerous diseases for vulnerable people.

Toxoplasmosis is typically acquired from eating raw or very rare meat, especially pork or mutton, or from contact with a cat’s litter box or feces, which is why pregnant women are advised to stay away from the litter box. Although in healthy adults it produces a mild flulike illness, all vulnerable people (the elderly, young children, the sick, immunosuppressed people) can be made very ill by it, and all should follow safe food practices and avoid cat litter and feces, just as pregnant women do. Freezing does not kill it; cooking does.

All these protozoa are killed by cooking. Raw and undercooked foods cause the trouble: drinking water and raw sausages (Cryptosporidium); strawberries and salad vegetables (Giardia); raw or undercooked beef and pork (Sarcocystis); raspberries, basil (or pesto made from it), and lettuce (Cyclospora). Worldwide, contaminated water and other foods are also sources.

Because raw fruits and vegetables are so often the carriers of these organisms, washing such foods carefully is important.


Many viruses are spread through foods. Among the most significant of these are the Hepatitis A virus, Norwalk-type viruses, and rotaviruses. These viral illnesses usually cause vomiting and sometimes, but not always, diarrhea or fever. Contaminated water is a common source. Fish, especially from cold northern waters, can be infected with viruses, and raw seafood is a major source of human infection. Insects and rodents can carry them. There are cases involving unheated foods such as salads and frosting. Vegetables can be contaminated with the hepatitis virus if they are watered with contaminated water or fertilized with human excrement. Strawberries from Mexico recently caused an outbreak. Milk can carry hepatitis. (Viruses can survive pasteurization.) Any food handled by infected persons that is not thoroughly cooked afterward is potentially contaminated.

Viruses may not be killed unless food is thoroughly heated. Some viruses are killed at temperatures exceeding 149°F; others must be heated to the boiling point. Steaming shellfish just to the point of opening is always inadequate. Acidity tends to deactivate viruses, and additives such as sulfite and ascorbate do too. Freezing kills some viruses; others can actually be transmitted by ice. According to one authority, “The process of depuration, in which shellfish are placed in sterile water for 48-72 hours to allow them to cleanse themselves, is effective against bacteria but not viruses.”

Poor hygiene is often a cause of viral contamination of food. Washing hands and taking effective measures against crosscontamination are all the more important given the heat resistance of some types of viruses.


Trichinella spiralis is the most common parasite to cause foodborne illness. It causes trichinosis, and is acquired when someone eats meat, usually pork, that contains the larvae of the T. spiralis worm. The larvae then mature in the victim’s stomach and go on to form new cysts in the muscle tissues of the new host. Early symptoms include abdominal pain, nausea, fever, and diarrhea; later there is muscle pain, tenderness, and fatigue. Untreated, the disease is extremely dangerous. Hogs are much less commonly infected with T. spiralis than they used to be, but there are still about fifty cases of trichinosis per year in the United States. T. spiralis is killed by heating or by freezing for twenty days at -10°F or lower. (The National Pork Producers Council recommends a temperature of 170°F for cooked pork, although the USDA calls for a slightly lower temperature, 160°.)

Tapeworms and flukes can be acquired from raw or undercooked meat or fish. Nematodes and anisakis, a roundworm, may be acquired from raw fish. Proper cooking offers protection from all of these.

What to Do About Contaminated Foods

Here is what the U.S. Department of Agriculture (USDA) recommends if you encounter suspect food in your kitchen or elsewhere:

Call the local health department if:

• The suspect food was served at a large gathering.

• The suspect food is from a restaurant, delicatessen, sidewalk vendor, or other commercial or institutional kitchen.

• The suspect food was prepared and packaged in a retail grocery store.

• The suspect food is a commercial product.

Other authorities to call:

Foodborne illness involving a USDA-inspected meat or poultry product may also be reported to the toll-free Meat and Poultry Hotline at 1-800-535-4555. (Callers in the 202 area code should call 447-3333.)

Foodborne illness involving other products that cross state lines may be reported to the nearest Food and Drug Administration (FDA) office, listed in the local phone book.

Foodborne illness involving products that are sold only within the state may be reported to the state health department or the state department of agriculture.

Try to have the following information available when calling:

Your name, address, and daytime phone number.

The name and address of the event, party, or establishment where the suspect food was consumed or purchased.

The date that the food was consumed and the date of purchase.

If the suspect food is a commercial product, have the container or wrapping in hand for reference while on the phone. Most meat and poultry products have a USDA or state inspection stamp and a number that identifies the plant where the product was manufactured. Many products also have a code indicating when the item was produced. This information can be vital in tracing a problem to its source.

Dispose of suspect foods safely:

To dispose of suspect home-canned products, it is best to enclose the food, in its original container, in a heavy garbage bag marked POISON and place the bag in a trash container that is not accessible to homeless people, children, or animals.

If a suspect canned food is opened in your kitchen, thoroughly scrub the can opener or other utensils, containers, counters, etc., that might have contacted the food or its container. Discard any sponges or cloths used in the cleanup. Wash your hands thoroughly.

Promptly launder any clothing that might have been spattered.

Preserve the evidence:

If a portion of the suspect food is available, wrap it securely in a heavy plastic bag and place it on ice in a secure container marked DANGER. Write down the name of the food, when it was consumed, and the date of the illness. Store the container away from children, pets, and other foods, in a location where it will not be mistaken for edible food. The sample may be useful to medical personnel treating the illness and to health authorities tracking the problem.

If they are available, also save the container, wrapping, and any metal clips used on the original package. This is where you can find the number that indicates the plant that a meat or poultry product is from.

Reduced-Oxygen or Modified-Atmosphere Packaged Foods

Many foods in the market are offered in “reduced-oxygen packaging” (known as ROP) or “modified-atmosphere packaging” (known as MAP). ROP foods often require continued refrigeration, at the store and at your home, and must be used by the date stamped on the package. In addition, some ROP foods are precooked and some are not, and some require refrigeration after opening but may look just like foods that do not. You always must follow package directions as to refrigeration, dates, and cooking.

ROP actually refers to a variety of packaging techniques, all of which reduce or remove the oxygen in the air inside the package, which may be replaced partly or wholly with another gas, such as nitrogen or carbon dioxide. The effect of reducing oxygen is to create a less favorable environment for the growth of many bacteria and thus to extend the life and storage quality of foods. It does not result in a product that you can put on your pantry shelf and expect to stay edible the way canned food does.

ROP techniques include all of these:

• Cook-chill (uses a plastic bag from which air has been expelled and which is filled with hot cooked food);

• Controlled-atmosphere packing, or CAP (the reduced-oxygen atmosphere in a package is maintained throughout the shelf life of the product by agents placed inside the package that bind oxygen or sachets that emit gases);

• Modified-atmosphere packaging, or MAP (packing a product in an atmosphere that contains a different proportion of gases, with reduced oxygen, from air, which normally contains 78.08 percent nitrogen, 20.96 percent oxygen, and 0.03 percent carbon dioxide);

• Sous vide (a sort of pasteurization that does not make food shelf-stable, involving partially cooked ingredients, vacuum-sealed packages, rapid cooling and reheating to specified temperatures before opening—many restaurants, even expensive ones you’d assume were making everything, use sous vide foods for appetizers or other components of meals);

• Vacuum packaging (reduces air and hermetically seals package to create a nearperfect vacuum).

In my local supermarket, I have found precut salad greens, packaged carrots, precooked polenta, meats, and many precooked foods in ROP packaging. Such products are not identified as ROP on their labels. Always read labels carefully to determine whether foods require refrigeration.

ROP foods pose complex safety problems to the food industry. Low acid foods that are stored in no-oxygen, nonbreathable packaging face the predictable problem: Clostridium botulinum grows in anaerobic environments, and some ROP foods are not processed in ways that would kill the spores of this bacterium. Keeping temperatures low helps to discourage its growth, but improper refrigeration would permit it to grow and create its deadly toxin. ROP also inhibits the growth of spoilage bacteria that could alert you to a problem by producing odors, rot, or slime; in other words, the food may continue to look perfectly fresh even though it is deadly. Other bacteria are also worrisome in some ROP products. Bacteria that continue to grow slowly in relatively low temperatures, such as Listeria, have an extralong time to grow with extended-life products. If ROP foods were to be held at improper temperatures, these and other pathogens might reach dangerous levels. The food industry’s answer to these sorts of problems is often to provide other barriers to the growth of bacteria besides low temperature—such as salt or acid. But some ROP foods lack fall-back barriers. “Use-by” dates thus offer important back-up protection in some cases.

In the meantime, studies show that “temperature abuse” routinely happens both in retail establishments and homes. According to Supermarket News (October 13, 1997): “Checks on temperatures of modified-atmosphere packages of fresh-cut salads [in retail establishments] over the past three years have showed a high level of abuse … Of 300 packages tested, 78% had a temperature greater than 45°F … What’s more, 17.5% of the 300 packages had a temperature greater than 55 degrees.” The 1999 Food Code complains that many people in their homes, too, do not maintain cold enough refrigerators for safety of ROP foods.

ROP packaging is considered safe by the 1999 Food Code when properly carried out by trained people, when there is no recontamination of food during processing, and when proper refrigeration is used at every step of processing, packing, distribution, and storing—including home storage. Although incidents of food poisoning involving ROP foods seem to be rare in recent years—outbreaks involving vacuum-packed fish occurred some years ago, causing several deaths—some experts fear we could see more of them unless we become more aware of the refrigeration requirements for ROP foods.

If you purchase ROP foods, here are some safety guidelines that the facts seem to warrant:

• Buy ROP foods only if they bear a “use-by” date which has not expired, and scrupulously observe such dates at home.

• Look for and follow label instructions as to storage (in the refrigerator or freezer) carefully!

• Carefully observe the refrigeration of ROP foods in supermarket cases. Make sure they feel cold to the touch. Buy only from highly reputable markets. Observe the habits at your market.

• Keep ROP foods that require refrigeration carefully refrigerated at home.

• If an ROP package contains precut fruits, salad greens, or vegetables, use it quickly after opening. Cut produce no longer has natural resistance to invasion by microbes. It is going to go bad quickly.

• If salad greens in a sealed package say “washed” and “ready to eat,” some reliable authorities say you need not wash them before eating them, especially if they are products of large, reputable food companies. (I would wash even these, however, if they were to be served to any vulnerable people, such as the very young, the elderly, or the sick or immunosuppressed.) Always wash prepackaged salads that do not explicitly say “washed” and “ready to eat.” And wash any greens sold in bulk or in open displays or that are not in a sealed package, even if they are said to be “washed.”

• Carefully follow the instructions on the label regarding cooking.

• If you are going to freeze an ROP product, do so quickly after buying it.

Cooking By-Products: Safe Cooking with Meats, Fats, and Oils

If you have a gas stove, keep the flame well adjusted so as to prevent carbon monoxide emissions. Some research suggests that combustion by-products from gas stoves (and other stoves that produce flames), such as nitrogen dioxide, can aggravate asthma, increase rates of respiratory problems, and reduce lung function. Some kitchen air pollution is also produced by the cooking itself—smoke or tiny droplets of oils and other foods, for example. Keeping the windows open whenever possible and making sure the stove has an exhaust to the outside helps significantly to reduce the concentrations of all these and other possible irritants in the air.

Research suggests that certain cooking techniques are associated with the creation of carcinogens in meats. High-temperature methods of cooking can produce “heterocyclic amines,” or HCAs, in cooked muscle meats. HCAs are suspected carcinogens. Although no one knows whether or to what extent they really pose a cancer risk, it is known that the higher the temperature and the longer the cooking time, the more HCAs are formed. The cooking techniques most associated with their production in meats are frying, broiling, barbecuing, and grilling—particularly charcoal grilling. Microwaving, stewing, boiling, and poaching cause little or no formation of these substances, presumably because all these techniques cook foods at temperatures of 212°F or lower. Oven roasting and baking fall in the middle, producing more than the latter and less than the former methods. Partially cooking meats in the microwave, and finishing cooking by other methods, is recommended as a means of reducing HCAs. The liquid that forms when meats are cooled contains the precursors of HCAs. If you pour it off, the amount of HCAs in the cooked food is reduced. In addition, those who wish to reduce their consumption of HCAs can eat meats cooked medium instead of well done and avoid gravy made from meat drippings.

Higher-temperature cooking of fats and oils, too, is thought to produce carcinogenic and unhealthy substances in the air as well as in foods. (This is yet another reason why you should choose lean cuts of meat and trim away all visible fat, aside from the benefits in weight control and heart-healthiness.) The production of toxic (and bad-tasting) compounds from the breakdown of fats and oils tends to occur at a temperature called the “smoke point,” when smoky fumes are produced from the overheated oils—a sight every cook is familiar with. You can choose cooking oils with higher smoke points. Vegetable oils, generally speaking, have higher smoke points than animal fats and oils. But among vegetable oils, sesame oil, extra-virgin olive oil, and Crisco—a hydrogenated vegetable oil—have low smoke points, in the range of 350° to 400°F, comparable to that of lard and butter; clarified butter, or ghee, and non-virgin olive oil have higher smoke points than regular butter and extra-virgin olive oil. Peanut oil, safflower oil, grape seed oil, canola (rape seed) oil, and corn oil all have high smoke points of around 440°F to 450°F.

Fats and oils get rancid—oxidize—just sitting on the shelf and aging; cooking oxidizes fats rapidly. Do not reuse cooking fats and oils. The old-fashioned habit of keeping a jar of cooking fat on the stovetop and pouring fats in and out of it for weeks on end was extremely unhealthy, but, fortunately, it has all but disappeared.

But do not use chlorine bleach on nonstainless steel, copper, aluminum, or silver. It may be used on stainless steel but not for extended periods of time.

You may read recommendations to use stronger recipes. The USDA, however, says this recipe is effective. Stronger solutions might leave residues or cause unpleasant bleach smells. In other places in this book, such as chapter 30, different recipes are recommended for other purposes.

Bacteria have been found to create an invisible, strongly adhering, slimy layer or film of cells, called a biofilm, on even hard and smooth surfaces such as stainless steel. Some research indicates that a biofilm is not easily removed with chemical means alone—for example, detergent or sanitizer—because the film prevents penetration by the chemical. Mechanical force, such as a stream of hard-running water or scrubbing, was found to be important in getting the film off. (“Microbial Attachment Similar for Wooden, Plastic Cutting Boards,” Food Chemical News, September 30, 1996.)

The material in this section is excerpted from the USDA Food Safety Inspection Service booklet “Preventing Foodborne Illness,” Home and Garden Bulletin No. 247, September 1990, pages 20-21. It has been partly reordered.



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