Milk-Borne Infectious Diseases From Microbes By Ingrid Koo, PhD Updated September 24, 2016 It’s the first food we taste. It’s in pasta sauces, candies, pastries, custards, cheeses, yogurts, and ice cream. Milk is arguably one of the most versatile ingredients among cooks and a staple in most households. However, as an animal product that is full of nutrients, there are several infectious diseases associated with microbe-contaminated milk and milk products. The good news is that most of these microbes are killed by pasteurization, and so in reality, infections due to milk and cheese are pretty rare -- but still possible. This is why we pasteurize milk. How Does Cow’s Milk Get Contaminated? Just like all people carry microbes, all animals do as well. Sometimes the microbes that cows carry can be a problem. Some dairy cows spend much of their time grazing in pastures, where they come in contact with a variety of environmental microbes. In other cases, cows are confined to buildings, where in more crowded conditions bacteria can grow and spread from cow to cow.

In addition, many microbes that are “commensal” organisms (that co-exist with cows without causing disease) may be considered human pathogens. Dairy processing facilities have many routes for the entry of contaminating microbes. First, as a nutrient-rich liquid, milk provides an ideal environment for microbial growth. Second, dairy processing plants are full of areas where “foot traffic” from employees can be accompanied by microbes. Infectious Microbes Found in Cow’s Milk Bacillus cereus: These bacteria produce a toxin that can cause diarrhea and another that causes vomiting. Bacillus cereus spores are heat-resistant and may survive pasteurization. There have even been very rare cases linked to dried milk and dried infant formula. Brucella: Brucella is a bacterial microbe that is found in unpasteurized dairy products. Brucella infection, or Brucellosis, has also been called “Undulant Fever” because of the regular recurrence of fever associated with the disease. Campylobacter jejuni: Campylobacter jejuni is the most common bacteria to cause diarrheal disease in the U.S. and is found in raw milk and poultry.

It has an increased chance of causing disease when consumed in milk, because the basic pH of milk neutralizes the acidity of the stomach. Coxiella burnetii: Coxiella infects a variety of animals, including livestock and pets. The microbe can be found in cow’s milk and is resistant to heat and drying. Infection by Coxiella results in Q fever, a high fever that may last up to 2 weeks. E. coli O157:H7: This particular strain of E. coli has been associated with a number of food-borne outbreaks and is the cause of bloody diarrhea. Frequently associated with dairy cattle, microbial contamination of raw milk and soft cheeses can result in disease. Listeria monocytogenes : Listeria is a common bacterial pathogen that is found in soft cheeses and unpasteurized milk. It can even survive below freezing temperatures and can therefore withstand refrigeration. It is particularly dangerous to individuals who have weakened immune systems, including pregnant women, AIDS patients, and the very young and very old.

Mycobacterium avium subspecies paratuberculosis: This strain of mycobacteria can withstand pasteurization and has been associated with the development of Crohn’s disease, also known as inflammatory bowel syndrome. However, whether or not these bacteria can actually infect humans remains controversial. Mycobacterium: The cause of “consumption,” a horrific wasting disease that first affects the lungs, Mycobacterium bovis is associated with consumption of raw milk and was one of the most common contaminants prior to the practice of pasteurization. It's like the tuberculosis (or TB) we have now, but a different bacteria but related bacteria causes it. This type of TB is something we don't see much of any more because of work to make sure cows don't carry or spread it to us. M. bovis causes tuberculosis in cows and can be passed to humans via unpasteurized cow's milk, causing a disease that is very similar to M. tuberculosis. Salmonella : Salmonella contamination of raw milk and milk products has been the source of several outbreaks in recent years. Symptoms include diarrhea and high fever. Staphylococcus aureus : Staph aureus produces a toxin that causes explosive vomiting.

The disease may be considered a consequence of actual food poisoning from simply consuming the toxin, rather than from an actual infection. Yersinia enterocolitis: Associated with raw milk and ice cream, among other foods, contamination is believed to be a consequence of a breakdown in sanitization and sterilization techniques at dairy processing facilities. What about Mad Cow Disease? Mad Cow Disease, also known as bovine spongiform encephalitis (BSE), is a disease that affects the nervous system and is caused by an infectious protein called a “prion.” Consumption of meat from cattle with BSE can result in transmission of the disease. In humans, the disease is called “transmissible spongiform encephalopathy” or “variant Creutzfeldt-Jakob disease.” Fortunately for the dairy industry and milk consumers, the infectious prion has not been found in milk from infected cows, nor has transmission through drinking of cow’s milk been reported. In short, you can’t get Mad Cow Disease from milk. How to Prevent Milk-borne Infectious Diseases: Don’t drink raw milk. Drink only pasteurized milk. Keep dairy products refrigerated within the expiration date marked on the package.

Be careful when you travel to developing nations, follow the recommended sanitary precautions for the country you are in and do not eat raw dairy products. Sources: Boor, KJ. Fluid Dairy Product Quality and Safety: Looking to the Future. J. Dairy Sci. 84:1-11 (2001) Foodborne Illness. US Food and Drug Administration. Center for Food Safety and Applied Nutrition Rowan NJ et al. Putative virulence factor expression by clinical and food isolates of Bacillus spp. after growth in reconstituted infant milk formulae. Appl Environ Microbiol. 2001 Sep;67(9):3873-81. Continue Reading Vitamins & Minerals in Milk | MilkFacts.info Cave Aging Shared Education and Information Network Vitamins & Minerals in Milk This page describes the Vitamins and Minerals present in milk, and the Effects of Heat Treatments and Light Exposure on the Vitamin and Mineral Content in Milk . A description of the nutritional function of vitamins and minerals is provided on the Nutritional Components in Milk page in the Nutrition Facts section. For more details on the vitamins and minerals in milk, see references by Flynn et al.

(1997) , Fox and McSweeney (1998) , Holt (1995) , and Öste et al. (1997) . Vitamins in Milk Vitamins have many roles in the body, including metabolism co-factors, oxygen transport and antioxidants. They help the body use carbohydrates, protein, and fat. The specific content of vitamins in milk is listed in the Nutrient Content Tables in the Nutrition Facts section. Milk contains the water soluble vitamins thiamin (vitamin B1), riboflavin (vitamin B2), niacin (vitamin B3), pantothenic acid (vitamin B5), vitamin B6 (pyridoxine), vitamin B12 (cobalamin), vitamin C, and folate. Milk is a good source of thiamin, riboflavin and vitamin B12 . Milk contains small amounts of niacin, pantothenic acid, vitamin B6, vitamin C, and folate and is not considered a major source of these vitamins in the diet. Milk contains the fat soluble vitamins A, D, E, and K.

The content level of fat soluble vitamins in dairy products depends on the fat content of the product. Reduced fat (2% fat), lowfat (1% fat), and skim milk must be fortified with vitamin A to be nutritionally equivalent to whole milk. Fortification of all milk with vitamin D is voluntary. Milk contains small amounts of vitamins E and K and is not considered a major source of these vitamins in the diet. Minerals in Milk Minerals have many roles in the body including enzyme functions, bone formation, water balance maintenance, and oxygen transport. The specific content of minerals in milk is listed in the Nutrient Content Tables in the Nutrition Facts section. Milk is a good source of calcium, magnesium, phosphorus, potassium, selenium, and zinc. Many minerals in milk are associated together in the form of salts, such as calcium phosphate. In milk approximately 67% of the calcium, 35% of the magnesium, and 44% of the phosphate are salts bound within the casein micelle and the remainder are soluble in the serum phase. The fact that calcium and phosphate are associated as salts bound with the protein does not affect the nutritional availability of either calcium or phosphate.

Milk contains small amounts of copper, iron, manganese, and sodium and is not considered a major source of these minerals in the diet. Effects of Heat Treatments & Light Exposure on the Vitamin & Mineral Content in Milk The mild heat treatment used in the typical high temperature short time (HTST) pasteurization of fluid milk does not appreciably affect the vitamin content. However, the higher heat treatment used in ultra high temperature (UHT) pasteurization for extended shelf combined with the increased storage life of these products does cause losses of some water-soluble vitamins. Thiamin is reduced from 0.45 to 0.42 mg/L, vitamin B 12 is reduced from 3.0 to 2.7 µg/L, and vitamin C is reduced from 2.0 to 1.8 mg/L ( Potter et al., 1984 ). Riboflavin is a heat stable vitamin and is not affected by severe heat treatments. Calcium phosphate will migrate in and out of the casein micelle with changes in temperature. This process is reversible at moderate temperatures. This does not affect the nutritional properties of milk minerals.

At very high temperatures the calcium phosphate may precipitate out of solution which causes irreversible changes in the casein micelle structure. Exposure to light will decrease the riboflavin and vitamin A content in milk. Milk should be stored in containers that provide barriers to light (opaque plastic or paperboard) to maximize vitamin retention. Cheese Production | MilkFacts.info Cheese Production Cave Aging Shared Education and Information Network Cheese Production This page describes the general production of cheese and includes the legal Cheese Definitions , Ingredients , Bacterial Cultures , and General Manufacturing Procedure . Cheese Definitions Cheese comes in many varieties. The variety determines the ingredients, processing, and characteristics of the cheese. The composition of many cheeses is defined by Standards of Identity in the U.S. Code of Federal Regulations (CFR) . Cheese can be made using pasteurized or raw milk. Cheese made from raw milk imparts different flavors and texture characteristics to the finished cheese. For some cheese varieties, raw milk is given a mild heat treatment (below pasteurization) prior to cheese making to destroy some of the spoilage organisms and provide better conditions for the cheese cultures.

Cheese made from raw milk must be aged for at least 60 days, as defined in the CFR, section 7 CFR 58.439 , to reduce the possibility of exposure to disease causing microorganisms (pathogens) that may be present in the milk. For some varieties cheese must be aged longer than 60 days. Cheese can be broadly categorized as acid or rennet cheese, and natural or process cheeses. Acid cheeses are made by adding acid to the milk to cause the proteins to coagulate. Fresh cheeses, such as cream cheese or queso fresco, are made by direct acidification. Most types of cheese, such as cheddar or Swiss, use rennet (an enzyme) in addition to the starter cultures to coagulate the milk. The term “natural cheese” is an industry term referring to cheese that is made directly from milk. Process cheese is made using natural cheese plus other ingredients that are cooked together to change the textural and/or melting properties and increase shelf life. Ingredients The main ingredient in cheese is milk. Cheese is made using cow, goat, sheep, water buffalo or a blend of these milks. The type of coagulant used depends on the type of cheese desired.

For acid cheeses, an acid source such as acetic acid (the acid in vinegar) or gluconodelta-lactone (a mild food acid) is used. For rennet cheeses, calf rennet or, more commonly, a rennet produced through microbial bioprocessing is used. Calcium chloride is sometimes added to the cheese to improve the coagulation properties of the milk. Flavorings may be added depending on the cheese. Some common ingredients include herbs, spices, hot and sweet peppers, horseradish, and port wine. Bacterial Cultures Cultures for cheese making are called lactic acid bacteria (LAB) because their primary source of energy is the lactose in milk and their primary metabolic product is lactic acid. There is a wide variety of bacterial cultures available that provide distinct flavor and textural characteristics to cheeses. For a more detailed description of cheese cultures and microbiology, see Fox (2004) , Kosikowski and Mistry (1997) , and Law (1997) . Starter cultures are used early in the cheese making process to assist with coagulation by lowering the pH prior to rennet addition.

The metabolism of the starter cultures contribute desirable flavor compounds, and help prevent the growth of spoilage organisms and pathogens. Typical starter bacteria include Lactococcus lactis subsp. lactis or cremoris, Streptococcus salivarius subsp. thermophilus, Lactobacillus delbruckii subsp. bulgaricus, and Lactobacillus helveticus. Adjunct cultures are used to provide or enhance the characteristic flavors and textures of cheese. Common adjunct cultures added during manufacture include Lactobacillus casei and Lactobacillus plantarum for flavor in Cheddar cheese, or the use of Propionibacterium freudenreichii for eye formation in Swiss. Adjunct cultures can also be used as a smear for washing the outside of the formed cheese, such as the use of Brevibacterium linens of gruyere, brick and limburger cheeses. Yeasts and molds are used in some cheeses to provide the characteristic colors and flavors of some cheese varieties. Torula yeast is used in the smear for the ripening of brick and limberger cheese.

Examples of molds include Penicillium camemberti in camembert and brie, and Penicillium roqueforti in blue cheeses. General Manufacturing Procedure The temperatures, times, and target pH for different steps, the sequence of processing steps, the use of salting or brining, block formation, and aging vary considerably between cheese types. The following flow chart provides a very general outline of cheese making steps. The general processing steps for Cheddar cheese are used for illustration. For a more detailed explanation see the literature references by Fox (2004) , Kosikowski and Mistry (1997) , Law (1997) , Walstra et al. (1999) , and the website by Goff , . General Cheese Processing Steps Package The times, temperatures, and target pH values used for cheddar cheese will depend on individual formulations and the intended end use of the cheese. These conditions can be adjusted to optimize the properties of Cheddar cheese for shredding, melting, or for cheese that is meant to be aged for several years. 1. Standardize Milk Milk is often standardized before cheese making to optimize the protein to fat ratio to make a good quality cheese with a high yield 2.

Pasteurize/Heat Treat Milk Depending on the desired cheese, the milk may be pasteurized or mildly heat-treated to reduce the number of spoilage organisms and improve the environment for the starter cultures to grow. Some varieties of milk are made from raw milk so they are not pasteurized or heat-treated. Raw milk cheeses must be aged for at least 60 days to reduce the possibility of exposure to disease causing microorganisms (pathogens) that may be present in the milk. 3. Cool Milk Milk is cooled after pasteurization or heat treatment to 90°F (32°C) to bring it to the temperature needed for the starter bacteria to grow. If raw milk is used the milk must be heated to 90°F (32°C). 4. Inoculate with Starter & Non-Starter Bacteria and Ripen The starter cultures and any non-starter adjunct bacteria are added to the milk and held at 90°F (32°C) for 30 minutes to ripen. The ripening step allows the bacteria to grow and begin fermentation, which lowers the pH and develops the flavor of the cheese. 5.

Add Rennet and Form Curd The rennet is the enzyme that acts on the milk proteins to form the curd. After the rennet is added, the curd is not disturbed for approximately 30 minutes so a firm coagulum forms. 6. Cut Curd and Heat The curd is allowed to ferment until it reaches pH 6.4. The curd is then cut with cheese knives into small pieces and heated to 100°F (38°C). The heating step helps to separate the whey from the curd. 7. Drain whey The whey is drained from the vat and the curd forms a mat. 8. Texture curd The curd mats are cut into sections and piled on top of each other and flipped periodically. This step is called cheddaring. Cheddaring helps to expel more whey, allows the fermentation to continue until a pH of 5.1 to 5.5 is reached, and allows the mats to "knit" together and form a tighter matted structure. The curd mats are then milled (cut) into smaller pieces. 9.

Dry Salt or Brine For cheddar cheese, the smaller, milled curd pieces are put back in the vat and salted by sprinkling dry salt on the curd and mixing in the salt. In some cheese varieties, such as mozzarella, the curd is formed into loaves and then the loaves are placed in a brine (salt water solution). 10. Form Cheese into Blocks The salted curd pieces are placed in cheese hoops and pressed into blocks to form the cheese. 11. Store and Age The cheese is stored in coolers until the desired age is reached. Depending on the variety, cheese can be aged from several months to several years. 12. Package Cheese may be cut and packaged into blocks or it may be waxed. Salmonella | FoodSafety.gov FoodSafety.gov Text Size: A A A Salmonella Salmonella, the name of a group of bacteria, is one of the most common causes of food poisoning in the United States. Usually, symptoms last 4-7 days and most people get better without treatment. But, Salmonella can cause more serious illness in older adults, infants, and persons with chronic diseases. Salmonella is killed by cooking and pasteurization.

Sources Food: Contaminated eggs, poultry, meat, unpasteurized milk or juice, cheese, contaminated raw fruits and vegetables (alfalfa sprouts, melons), spices, and nuts Animals and their environment: Particularly reptiles (snakes, turtles, lizards), amphibians (frogs), birds (baby chicks) and pet food and treats. Incubation Period Diarrhea, fever, abdominal cramps, vomiting Duration of Illness 4-7 days What Do I Do? Drink plenty of fluids and get rest. If you cannot drink enough fluids to prevent dehydration or if your symptoms are severe, call your doctor. Antibiotics may be necessary if the infection spreads from the intestines to the blood stream. How Can I Prevent It? Avoid eating high-risk foods, including raw or lightly cooked eggs, undercooked ground beef or poultry, and unpasteurized milk Keep food properly refrigerated before cooking. Clean hands with soap and warm water before handling food. Clean surfaces before preparing food on them. Separate cooked foods from ready-to-eat foods. Do not use utensils on cooked foods that were previously used on raw foods and do not place cooked foods on plates where raw foods once were unless it has been cleaned thoroughly.

Cook foods to a safe internal temperature. Use a meat thermometer to make sure foods are cooked to a safe temperature. Chill foods promptly after serving and when transporting from one place to another. Wash your hand after contact with animals, their food or treats, or their living environment. General Information Listeria | FoodSafety.gov FoodSafety.gov Text Size: A A A Listeria Listeria is the name of a bacteria found in soil and water and some animals, including poultry and cattle. It can be present in raw milk and foods made from raw milk. It can also live in food processing plants and contaminate a variety of processed meats. Listeria is unlike many other germs because it can grow even in the cold temperature of the refrigerator. Listeria is killed by cooking and pasteurization.

Ready-to-eat deli meats and hot dogs Refrigerated pâtés or meat spreads Unpasteurized (raw) milk and dairy products Soft cheese made with unpasteurized milk, such as queso fresco, Feta, Brie, Camembert Refrigerated smoked seafood Fever, stiff neck, confusion, weakness, vomiting, sometimes preceded by diarrhea Duration of Illness People with weakened immune systems Organ transplant patients who are receiving drugs to prevent the body from rejecting the organ People with certain diseases, such as: HIV/AIDS or other autoimmune diseases Cancer Diabetes What Do I Do? If you are very ill with fever or stiff neck, consult your doctor immediately. Antibiotics given promptly can cure the infection and, in pregnant women, can prevent infection of the fetus. How Do I Prevent It? Do not drink raw (unpasteurized) milk, and do not eat foods that have unpasteurized milk in them. Wash hands, knives, countertops, and cutting boards after handling and preparing uncooked foods. Rinse raw produce thoroughly under running tap water before eating. Keep uncooked meats, poultry, and seafood separate from vegetables, fruits, cooked foods, and ready-to-eat foods.

Thoroughly cook raw food from animal sources, such as meat, poultry, or seafood to a safe internal temperature. Wash hands, knives, countertops, and cutting boards after handling and preparing uncooked foods. Consume perishable and ready-to-eat foods as soon as possible. Persons in higher risk groups should heat hot dogs, cold cuts, and deli meats before eating them. At Risk Populations Listeriosis, an infection caused by Listeria, can pose major risks for certain populations. Namely, pregnant women, older adults, and individuals with weakened immune systems are at greater risk. Pregnant Women Pregnant women are approximately 20 times more likely than other healthy adults to get listeriosis. In pregnant women, it is typically a mild, flu-like illness. In the child, listeriosis can lead to miscarriage, stillbirth, or life-long health problems. Common Questions & Answers from pregnant women about Listeriosis Older Adults As adults age, it is normal for their bodies not to work as well as they did when they were younger. Changes in their organs and body systems are expected as they grow older. These changes often make them more susceptible to contracting a foodborne illness such as Listeriosis.

A need-to-know guide for those 65 years of age and older Other At Risk Populations A properly functioning immune system works to clear infection and other foreign agents from the body. However, certain conditions including cancer and its treatments, diabetes, HIV/AIDS, and organ or bone marrow transplants can weaken the immune system – making the body more susceptible to many types of infections, including foodborne illness such as Listeriosis. Food Safety for Older Adults Food Safety for Older Adults A need-to-know guide for those 65 years of age and older U.S. Department of Agriculture Food Safety and Inspection Service U.S. Department of Health and Human Services Food and Drug Administration September 2006; Slightly revised September 2011 Food safety is important for everyone – but it’s especially important for you. That’s why the U.S. Department of Agriculture’s Food Safety and Inspection Service and the U.S. Department of Health and Human Services’ Food and Drug Administration have prepared this booklet. It is designed to provide practical guidance on how to reduce your risk of foodborne illness. In addition to this guide, we encourage you to check with your physician or healthcare provider to indentify foods and other products that you should avoid.

You have a special need for this important information . . . so read on! What’s Inside Additional Food Safety Resources Foodborne Illness in the United States When certain disease-causing bacteria, viruses or parasites contaminate food, they can cause foodborne illness. Another word for such a bacteria, virus, or parasite is “pathogen.” Foodborne illness, often called food poisoning, is an illness that comes from a food you eat. The food supply in the United States is among the safest in the world – but it can still be a source of infection for all persons. According to the Centers for Disease Control and Prevention, 48 million persons get sick, 128,000 are hospitalized, and 3,000 die from foodborne infection and illness in the United States each year. Many of these people are children, older adults, or have weakened immune systems and may not be able to fight infection normally. Since foodborne illness can be serious – or even fatal – it is important for you to know and practice safe food-handling behaviors to help reduce your risk of getting sick from contaminated food.

Food Safety: It’s Especially Important for You As we age, it is normal for our bodies not to work as well as they did when we were younger. Changes in our organs and body systems are expected as we grow older. These changes often make us more susceptible to contracting a foodborne illness or food poisoning. For example, our stomach and intestinal tract may hold on to foods for a longer period of time; our liver and kidneys may not readily rid our bodies of toxins; and our sense of taste or smell may be altered. By the age of 65, many of us have been diagnosed with one or more chronic conditions, such as diabetes, arthritis, cancer, or cardiovascular disease, and are taking at least one medication. The side effects of some medications or the chronic disease process may weaken the immune system, causing older adults to be more susceptible to contracting a foodborne illness. After the age of 75 years and older, many adults often have a weakened immune system and are at an increased risk for contracting a foodborne illness. Essentially, as we age, our immune system and other organs in our bodies have become a bit sluggish in recognizing and ridding the body of harmful bacteria and other pathogens that cause infections, such as foodborne illness.

Should older adults contract a foodborne illness, you are more likely to have a lengthier illness, undergo hospitalization, or even die. To avoid contracting a foodborne illness, older adults must be especially vigilant when handling, preparing, and consuming foods. Make safe handling a lifelong commitment to minimize your risk of foodborne illness. Be aware that as you age, your immunity to infection naturally is weakened. Major Pathogens That Cause Foodborne Illness Campylobacter back to top Eating at Home: Making Wise Food Choices Some foods are more risky for you than others. In general, the foods that are most likely to contain harmful bacteria or viruses fall in two categories: Uncooked fresh fruits and vegetables Some animal products, such as unpasteurized (raw) milk; soft cheeses made with raw milk; and raw or undercooked eggs, raw meat, raw poultry, raw fish, raw shellfish and their juices; luncheon meats and deli-type salads (without added preservatives) prepared on site in a deli-type establishment. Interestingly, the risk these foods may actually pose depends on the origin or source of the food and how the food is processed, stored, and prepared.

Follow these guidelines (see chart below) for safe selection and preparation of your favorite foods. If You Have Questions ….… about Wise Food Choices: Be sure to consult with your doctor or healthcare provider. He or she can answer any specific questions or help you in your choices. …about Particular Foods: If you are not sure about the safety of a food in your refrigerator, don’t take the risk. When in doubt, throw it out! Wise choices in your food selections are important. All consumers need to follow the Four Basic Steps to Food Safety: Clean, Separate, Cook and Chill. Common Foods: Select the Lower Risk Options Type of Food back to top Taking Care: Handling and Preparing Food Safely Foodborne pathogens are sneaky. Food that appears completely fine can contain pathogens --disease-causing bacteria, viruses, or parasites -- that can make you sick. You should never taste a food to determine if it is safe to eat. As an older adult, it is especially important that you – or those preparing your food – are always careful with food handling and preparation. The easiest way to do this is to Check Your Steps -- clean, separate, cook, and chill – from the Food Safe Families Campaign.

Four Basic Steps to Food Safety 1. Clean: Wash hands and surfaces often Bacteria can spread throughout the kitchen and get onto cutting boards, utensils, counter tops, and food. To ensure that your hands and surfaces are clean, be sure to: Wash hands in warm soapy water for at least 20 seconds before and after handling food and using the bathroom, changing diapers, or handling pets. Wash cutting boards, dishes, utensils, and counter tops with hot soapy water between the preparation of raw meat, poultry, and seafood products and preparation of any other food that will not be cooked. As an added precaution, sanitize cutting boards and counter tops by rinsing them in a solution made of one tablespoon of unscented liquid chlorine bleach per gallon of water, or, as an alternative, you may run the plastic board through the wash cycle in your automatic dishwasher. Use paper towels to clean up kitchen surfaces. If using cloth towels, you should wash them often in the hot cycle of the washing machine. Wash produce. Rinse fruits and vegetables, and rub firm-skin fruits and vegetables under running tap water, including those with skins and rinds that are not eaten. With canned goods: remember to clean lids before opening.

2. Separate: Don’t cross-contaminate Cross-contamination occurs when bacteria are spread from one food product to another. This is especially common when handling raw meat, poultry, seafood, and eggs. The key is to keep these foods – and their juices – away from ready-to-eat foods. To prevent cross-contamination, remember to: Separate raw meat, poultry, seafood, and eggs from other foods in your grocery shopping cart, grocery bags, and in your refrigerator. Never place cooked food on a plate that previously held raw meat, poultry, seafood, or eggs without first washing the plate with hot soapy water. Don’t reuse marinades used on raw foods unless you bring them to a boil first. Consider using one cutting board only for raw foods and another only for ready-to-eat foods, such as bread, fresh fruits and vegetables, and cooked meat. 3. Cook: Cook to safe temperatures Foods are safely cooked when they are heated to the USDA-FDA recommended safe minimum internal temperatures, as shown on the “ Is it Done Yet ” chart. To ensure that your foods are cooked safely, always: Use a food thermometer to measure the internal temperature of cooked foods.

Check the internal temperature in several places to make sure that the meat, poultry, seafood, or egg product is cooked to safe minimum internal temperatures. Cook ground beef to at least 160 ºF and ground poultry to a safe minimum internal temperature of 165 ºF. Color of food is not a reliable indicator of safety or doneness. Reheat fully cooked hams packaged at a USDA-inspected plant to 140 ºF. For fully cooked ham that has been repackaged in any other location or for leftover fully cooked ham, heat to 165 ºF. Cook seafood to 145 F. Cook shrimp, lobster, and crab until they turn red and the flesh is pearly opaque. Cook clams, mussels, and oysters until the shells open. If the shells do not open, do not eat the seafood inside. Cook eggs until the yolks and whites are firm. Use only recipes in which the eggs are cooked or heated to 160 ºF.

Cook all raw beef, lamb, pork, and veal steaks, roasts, and chops to 145 ºF with a 3-minute rest time after removal from the heat source. Bring sauces, soups, and gravy to a boil when reheating. Heat other leftovers to 165 ºF. Reheat hot dogs, luncheon meats, bologna, and other deli meats until steaming hot or 165 ºF. When cooking in a microwave oven, cover food, stir, and rotate for even cooking. If there is no turntable, rotate the dish by hand once or twice during cooking. Always allow standing time, which completes the cooking, before checking the internal temperature with a food thermometer. Food is done when it reaches the USDA- FDA recommended safe minimum internal temperature. Is It Done Yet? In the Know: Becoming a Better Shopper Follow these safe food-handling practices while you shop. Carefully read food labels while in the store to make sure food is not past its “sell by” date.

Put raw packaged meat, poultry, or seafood into a plastic bag before placing it in the shopping cart so that its juices will not drip on – and contaminate – other foods. If the meat counter does not offer plastic bags, pick some up from the produce section before you select your meat, poultry, and seafood. Buy only pasteurized milk, cheese, and other dairy products from the refrigerated section. When buying fruit juice from the refrigerated section of the store, be sure that the juice label says it is pasteurized. Purchase eggs in the shell from the refrigerated section of the store. (Note: store the eggs in their original carton in the main part of your refrigerator once you are home.) For recipes that call for eggs that are raw or undercooked when the dish is served – homemade Caesar salad dressing and homemade ice cream are two examples – use either shell eggs that have been treated to destroy Salmonella by pasteurization or pasteurized egg products. When consuming raw eggs, using pasteurized eggs is the safer choice. Never buy food that is displayed in unsafe or unclean conditions. When purchasing canned goods, make sure that they are free of dents, cracks, or bulging lids.

(Once you are home, remember to clean each lid before opening the can.) Purchase produce that is not bruised or damaged. Check Your Steps: Check “Sell-By” date. Put raw meat, poultry, or seafood in plastic bags Buy only pasteurized milk, soft cheeses made with pasteurized milk, and pasteurized or juices that have been otherwise treated to control harmful bacteria. When buying eggs, purchase refrigerated shell eggs. If your recipe calls for raw eggs, purchase pasteurized, refrigerated liquid eggs. Don’t buy food displayed in unsafe or unclean conditions Food Product Dating Types of Open Dates: Open dating is found primarily on perishable foods such as meat, poultry, eggs, and dairy products. A“Sell-By” date tells the store how long to display the product for sale. You should buy the product before the date expires. A “Best if Used By (or Before)” date is recommended for best flavor or quality. It is not a purchase or safety date. A “Use-By” date is the last date recommended for the use of the product while at peak quality. The date has been determined by the manufacturer of the product. “Closed or coded dates” are packing numbers for use by the manufacturer.

“Closed” or “coded” dating might appear on shelf-stable products such as cans and boxes of food. Transporting Your Groceries Follow these tips for safe transporting of your groceries: Pick up perishable foods last, and plan to go directly home from the grocery store. Always refrigerate perishable foods within 2 hours of cooking or purchasing. Refrigerate within 1 hour if the temperature outside is above 90 °F. In hot weather, take a cooler with ice or another cold source to transport foods safely. back to top Being Smart When Eating Out Eating out can be lots of fun – so make it an enjoyable experience by following some simple guidelines to avoid foodborne illness. Remember to observe your food when it is served, and don’t ever hesitate to ask questions before you order. Waiters and waitresses can be quite helpful if you ask how a food is prepared. Also, let them know you don’t want any food item containing raw meat, poultry, seafood, sprouts, or eggs. Basic Rules for Ordering Ask whether the food contains uncooked ingredients such as eggs, sprouts, meat, poultry, or seafood. If so, choose something else. Ask how these foods have been cooked.

If the server does not know the answer, ask to speak to the chef to be sure your food has been cooked to a safe minimum internal temperature. If you plan to get a “doggy bag” or save leftovers to eat at a later time, refrigerate perishable foods as soon as possible – and always within 2 hours after purchase or delivery. If the leftover is in air temperatures above 90 °F, refrigerate within 1 hour. If in doubt, make another selection! back to top Tips for Transporting Food Keep cold food cold, at 40 °F or below. To be safest, place cold food in cooler with ice or frozen gel packs. Use plenty of ice or frozen gel packs. Cold food should be at 40 °F or below the entire time you are transporting it. Hot food should be kept at 140 °F or above. Wrap the food well and place in an insulated container. Stay “Food Safe” When Traveling Internationally Discuss your travel plans with your physician before traveling to other countries. Your physician may have specific recommendations for the places you are visiting, and may suggest extra precautions or medications to take on your travels.

For more information about safe food and water while traveling abroad, access the Centers for Disease Control and Prevention . back to top Foodborne Illness: Know the Symptoms Despite your best efforts, you may find yourself in a situation where you suspect you have a foodborne illness. Foodborne illness often presents itself with flu-like symptoms. These symptoms include: If you suspect you have a foodborne illness, follow these general guidelines: 1. Consult your physician or health care provider, or seek medical treatment as appropriate. As an older adult, you are at increased risk for severe infection. Contact your physician immediately if you develop symptoms or think you may be at risk. If you develop signs of infection as discussed with your physician, seek out medical advice and/or treatment immediately. 2. Preserve the food. If a portion of the suspect food is available, wrap it securely, label it to say “DANGER,” and freeze it. The remaining food may be used in diagnosing your illness and in preventing others from becoming ill. 3. Save all the packaging materials, such as cans or cartons. Write down the food type, the date and time consumed, and when the onset of symptoms occurred.

Write down as many foods and beverages you can recall consuming in the past week (or longer), since the onset time for various foodborne illnesses differ. Save any identical unopened products. If the suspect food is a USDA-inspected meat, poultry, or egg product, call the USDA Meat and Poultry Hotline, 1-888-MPHotline (188-674-6854). For all other foods, call the FDA office of Emergency Operations at 1-866-300-4374 or 301-796-8240. 4. Call your local health department … … if you believe you became ill from food you ate in a restaurant or other food establishment. The health department staff will be able to assist you in determining whether any further investigation is warranted. To locate your local health department, visit Health Guide USA . back to top More Information on Food Safety You may contact the USDA Food Safety and Inspection Service and HHS Food and Drug Administration to obtain additional food safety information in both English and Spanish. 9. Milk and milk products 9.

Milk and milk products Suitability for small-scale production Although cow's milk is the most popular in many countries, milk can be obtained from many different sources. For example, milk from goats and sheep makes a substantial contribution to the total milk production in countries of Eastern and Southern Europe, Malawi, and Barbados, whereas the water buffalo is a common source of milk in much of Asia. The table below illustrates some of the differences in composition between these milks. Woman milking a goat Milk is a perishable commodity and spoils very easily. Its low acidity and high nutrient content make it the perfect breeding ground for bacteria, including those which cause food poisoning (pathogens). Bacteria from the animal, utensils, hands, and insects may contaminate the milk, and their destruction is the main reason for processing. This preservation of the milk can be achieved by fermentation, heating, cooling, removal of water, and by concentration or separation of components, to produce foods such as butter or cheese. The degree to which milk consumption and processing occurs will differ from region to region. It is dependent upon a whole host of factors, including geographic and climatic conditions, availability and cost of milk, food taboos, and religious restrictions.

Where processing does exist, many traditional techniques can be found for producing indigenous milk products. These are more stable than raw milk and provide a means of preservation as well as adding variety to the diet. In addition, the introduction of western-style dairy products and the subsequent setting up of small-scale dairies has provided more choice of dairy products to the consumer. Nutritional significance Milk is often regarded as being nature's most complete food. It earns this reputation by providing many of the nutrients which are essential for the growth of the human body. Being an excellent source of protein and having an abundance of vitamins and minerals, particularly calcium, milk can make a positive contribution to the health of a nation. The realization of its nutritional attributes is clearly illustrated by the implementation of numerous 'school milk programmes' worldwide. Fermented-milk products such as yoghurt and soured milk contain bacteria from the Lactobacilli group. These bacteria occur naturally in the digestive tract and have a cleansing and healing effect. Therefore the introduction of fermented products into the diet can help prevent certain yeasts and bacteria which may cause illness. Many people suffer from a condition known as 'lactose intolerance'. This means that they are unable to digest the milk fat (lactose).

Such people can, however, tolerate milk if it is fermented to produce foods such as yoghurt. During fermentation, lactic acid producing bacteria break down lactose, and in doing so eliminate the cause of irritation. The quality of milk The type of animal, its quality, and its diet can lead to differences in the colour, flavour, and composition of milk. Infections in the animal which cause illness may be passed directly to the consumer through milk. It is therefore extremely important that quality-control tests are carried out to ensure that the bacterial activity in raw milk is of an acceptable level, and that no harmful bacteria remain in the processed products. Average composition (%) of milks of various mammals Species Standard testing procedures Milk fat The price paid for milk is usually dependent upon the milk-fat content, and this may be determined either at the collection stage or at the dairy using a piece of equipment known as a butyrometer. Additionally the specific gravity can be measured using a hydrometer. This can also be used as an aid to detect adulteration. Bacterial activity Routinely it is necessary to check the microbiological quality of raw milk using either methylene blue or resazurin dyes.

These tests indicate the activity of bacteria in the milk sample and the results determine whether the milk is accepted or rejected. Both tests work on the principle of the time taken to change the colour of the dye. The length of time taken is proportional to the number of micro-organisms present (the shorter the time taken, the higher the bacterial activity). It is preferable to use the resazurin test as this is less time-consuming. For these tests, basic laboratory equipment will be needed such as test-tubes, a water bath, accurate measuring equipment, and a supply of dyes. After collection the milk should ideally be stored at a temperature of 4°C or below. This is necessary to slow the growth of any contaminating bacteria. Phosphatase test For pasteurized milk, it is possible to ensure that pasteurization has been adequately achieved by testing for the presence of the enzyme phosphatase. The destruction of phosphatase is regarded as a reliable test to show that the milk has been sufficiently heat-processed, because this enzyme (present in raw milk) is destroyed by pasteurization conditions.

It is stressed that pasteurization is an effective safeguard against spoilage and food poisoning only if the milk is not re-contaminated after pasteurization. Processing Liquid milk Milk can be kept for longer periods of time if it is heated to destroy the bacteria or cooled to slow their growth. Pasteurization and sterilization are the two most commonly-used heat treatments. Technically, it is possible for both to be carried out on a small scale, but they are most usually performed on a larger industrial scale due to the need for qualified, experienced staff and accurate and strictly controlled hygienic processing conditions. Production stages for pasteurized and sterilized milk Product Store raw milk at 4°C Test for bacterial activity using resazurin/methylene blue Filter Refer to the Packaging chapter for details Homogenization Homogenization breaks up the oil droplets in milk and prevents the cream from separating out and forming a layer. This is of particular importance for sterilized milk which has a long shelf-life and when the formation of a cream layer is not desired. Additional changes include increased viscosity and a richer taste. Homogenizers are more usually designed for industrial-scale production, but it is possible to purchase smaller versions.

Filling The most common packaging material for both pasteurized and sterilized milk is glass bottles sealed with either foil or metal caps, although plastic bottles, plastic bags, and cardboard cartons are all used when bottles are not available or too expensive. Pasteurization Pasteurization is a relatively mild heat treatment, (usually performed below 100°C) which is used to extend the shelf-life of milk for several days. It preserves the milk by the inactivation of enzymes and destruction of heat-sensitive micro-organisms, but causes minimal changes to the nutritive value or sensory characteristics of a food. Some heat-resistant bacteria survive to spoil the milk after a few days, but these bacteria do not cause food poisoning. The time and temperature combination needed to destroy 'target' microorganisms will vary according to a number of complex inter-related factors. For milk, the heating time and temperature is either 63°C for 30 minutes or alternatively 72°C for 15 seconds. Only the former combination is possible on a small scale and for this the simplest equipment required is an open boiling pan. Better control is achieved using a steam jacketed pan, and this can be fitted with a stirrer to improve the efficiency of heating.

Both of these are batch processes which are suited to small-scale operation. A higher production rate may be possible using a tubular-coil pasteurizer. This equipment has been tested and has been successful for some fruit products but it is presently still at a developmental stage. Sterilization Sterilization is a more severe heat treatment designed to destroy all contaminating bacteria. The milk is sterilized at a temperature of 121°C maintained for 15-20 minutes. This can be achieved using a retort or pressure cooker. Unlike pasteurization, this process causes substantial changes to the nutritional and sensory quality of the milk. In some countries, flavoured milk has become a very popular product. However, sterilization is not recommended for small-scale production for the following reasons: · The cost of a retort and ancillary equipment is high for the small-scale processor. · It is essential that the correct heating conditions are carefully established and maintained for every batch of milk that is processed. If the milk is overheated, the quality is reduced, and it may have a rather burnt taste and aroma. · If the milk is not heated sufficiently, there is a risk that micro-organisms will survive and grow inside the bottle.

In low-acid foods such as milk, many types of bacteria including Clostridium botulinum can grow and cause severe food poisoning. · Due to the potential dangers from food poisoning, the skills of a qualified food technologist/microbiologist are required in order to routinely examine samples of sterilized milk that have been subjected to accelerated storage conditions. This requires a supply of microbiological media and equipment. In summary, the process of sterilization requires a considerable capital investment, the need for trained and experienced staff, regular maintenance of sophisticated equipment, and a comparatively high operating expenditure. Cooling Pasteurization does not destroy all of the micro-organisms, therefore the milk has to be cooled rapidly to prevent the growth of surviving bacteria. Cooling can be achieved on a small scale by using a bottle-cooling system. A system is outlined in the Packaging chapter. Storage Pasteurized milk has a shelf-life of 2-3 days if kept at 4°C. Maintaining this low temperature causes a substantial increase to the cost of transportation and distribution and is therefore a major disadvantage to the development of a small-scale pasteurized milk business.

If packaged in sealed bottles and stored at room temperature, sterilized milk should have a shelf-life in excess of six months. Separation of milk components Cream When milk is left to stand for some time, fat globules rise to the surface forming a layer of fat (or cream). This can be separated leaving behind skimmed milk as a by-product. There are different types of cream each with different fat concentrations: single (or light) cream contains 18 per cent milk fat whereas double (or heavy) cream normally contains 30 per cent milk fat. Cream is a luxury item and may be used as an accompaniment to coffee, as a filling in cakes, and an ingredient in ice cream. Separation Separation can very simply be achieved by removing the cream with a spoon, however this is a slow process during which the cream may spoil. For this reason it is more usual to use a manual or powered centrifuge. Production stages for cream Store bottles at 4°C Refrigerated storage 15.0 Pasteurization Cream may be pasteurized in a similar way to milk, using a similar time and temperature combination and the same equipment. Cream can also be sterilized but there is a considerable loss of quality.

Packaging and storage Cream can be packaged in glass jars or plastic pots sealed with foil lids. Pasteurized cream must be stored at a temperature of 4°C to have a shelf-life of several days. Refrigerated storage is necessary because cream is prone to rapid spoilage. Butter Butter is a semi-solid mass which contains approximately 80-85 per cent milk-fat and 15-20 per cent water. It is yellow/white in colour, with a bland flavour and a slightly salty taste. It is a valuable product that has a high demand for domestic use in some countries and as an ingredient in other food processing (e.g. for confectionery and bakery uses). The principles of preservation are: · to destroy enzymes and micro-organisms by pasteurizing the milk · to prevent microbial growth during storage by reducing the water content, by storing the product at a low temperature, and optionally by adding a small amount of salt during processing. Production stages for butter 15.0 Churning Churning disrupts the emulsion of fat and water and as a result the milk-fat separates out into granules. This process takes place in a butter churn.

Churning cream Churning is continued until fat granules are present and at this stage the mixture is drained to remove liquid that has separated from the granules. This liquid is known as buttermilk and can be used as either a beverage or as an ingredient in animal feed. Washing Clean water equivalent in weight to the buttermilk is added to the churn in order to wash the butter granules. The wash water is drained away. Churning is continued for a short time to compact the butter, and once this has been achieved it is removed from the churn. Forming and packaging Butter is kneaded to achieve a smooth and pliable texture. This can be done using simple hand-tools such as butter pats. Alternatively for higher production rates a specially-designed kneader can be used. Once the butter has a uniform and smooth texture it is formed into blocks with butter pats and packed in either greaseproof paper or foil wrappers. Working butter with butter pats Storage Due to its high fat composition, butter must be stored at temperatures below 10°C otherwise the fat becomes rancid and imparts undesirable 'off' flavours.

The water droplets in butter (20 per cent) can also allow bacteria to grow if it is not kept under cool conditions. Ghee Ghee is made from butter which has been heated and clarified. At ambient temperatures it is a semi-solid mass with a granular texture, but on melting (40°C+) it turns into a clear, thin liquid. It has a high demand in some countries for domestic use, as an ingredient for local food production (for example bakeries and confectionery manufacturers), and as an export commodity. Alternatively, cream is boiled gently to evaporate the water. During boiling the product is stirred continuously until the milk proteins start to coagulate, forming particles, and the colour of the cream darkens. Heating is stopped and the product is left to set. The particles settle at the bottom of the vessel and the milk-fat is separated. The principles of preservation are: · heating to destroy enzymes and contaminating microorganisms · to reduce the water-content by evaporation, and in doing so prevent the growth of micro-organisms. Production stages for ghee Store at ambient temperatures Packaging and storage Metal containers are normally used.

They should be thoroughly cleaned, especially if they are re-usable, and they should be made airtight. Alternatives to metal cans include coloured glass jars with metal lids, or ceramic pots sealed with cork/plastic stoppers. Ghee is usually stored at room temperatures as cold storage affects the granular texture. Thus ghee is useful for those consumers with no access to refrigeration. Cultured/fermented dairy products The technology of cultured milk products such as yoghurt, curd, and cheese is based upon the microbial conversion of the milk-sugar lactose to lactic acid (lactic acid accounts for the characteristic 'sourness' of such products). In order for the conversion to take place, lactic acid producing bacteria must be present. This may occur by allowing the milk to sour naturally, but it is better to introduce the appropriate bacteria as a starter culture. Starter cultures may be in the form of a small quantity of previously-cultured product or may be purchased as a commercially-prepared culture. Yoghurt/curd Yoghurt is a fermented milk product that evolved by allowing naturally-contaminated milk to sour at a warm temperature.

Yoghurt can be either unsweetened or sweetened, set, or stirred. Curd is the name given to a yoghurt-type product made from buffalo milk. The principles of preservation for yoghurt are: · Pasteurization of the raw milk to destroy contaminating microorganisms and enzymes. · An increase in acidity due to the production of lactic acid from lactose. This inhibits the growth of food-poisoning bacteria. · Storage at a low temperature to inhibit the growth of microorganisms. Production stages for set yoghurt Ingredients 15.0 Heating In the manufacture of yoghurt, milk is normally heated to 70°C for 15-20 minutes, using an open boiling pan, or alternatively a steam jacketed pan. Addition of starter culture The milk is cooled to between 30 40°C and inoculated with a mixed culture of Lactobacillus bulgaricus and Streptococcus thermophilus (usually in a ratio of 1:1). If a commercial starter-culture is used, the directions for use will be given.

However, if a culture from a previous batch is used, then it is usual to add 2-3 tablespoons per litre of prepared milk. Yoghurt of the stirred variety can be fermented in the mixing container. To make set yoghurt the inoculated milk should be poured into the individual pots before fermentation. Selling curd from a roadside stall Incubation The micro-organisms that produce yoghurt are most active within a temperature range of 32-47°C. Ambient temperatures are therefore not adequate and a heated incubator is needed. Small commercially-available yoghurt-makers consist of an electrically-heated base and a set of plastic or glass containers. Most yoghurt-makers make four or five individual half litre cups at a time. There are other simple and inexpensive ways of incubating yoghurt such as an insulated box, keeping the jars/pots surrounded by warm water, or by using thermos flasks (the latter is only suitable for stirred yoghurt). Incubation takes approximately five hours. When fermentation is complete, stirred yoghurt is cooled and flavoured or sweetened prior to packaging. In set yoghurt all ingredients are added before fermentation.

Packaging and storage Yoghurt or curd is commonly packaged in plastic pots fitted with a plastic lid, or heat-sealed with foil, although traditionally, curd is packaged in clay pots. Such pots are made from local materials and can be re-used or later used for cooking. The shelf-life of yoghurt is usually 3-8 days when stored at temperatures below 10°C. Cheese Cheese is made from milk by the combined action of lactic acid bacteria and the enzyme rennin (known as rennet). Just as cream is a concentrated form of milk fat, cheese is a concentrated form of milk-protein. The differences in cheeses that are produced in different regions result from variations in the composition and type of milk, variations in the process, and the bacteria used. The different cheese varieties can be classified as either hard or soft. Collecting milk for cheese-making Hard cheeses such as Cheddar and Edam have most of the whey drained out and are pressed. Soft cheeses such as paneer contain some of the whey and are not pressed. Many indigenous cheeses are soft types. The hardness, flavour, and other qualities of a cheese can be varied by changes to the process conditions, to suit local tastes.

However the principal steps of a cheese-making process are basically the same. The principles of preservation are: · the raw milk is pasteurized to destroy most enzymes and contaminating bacteria · fermentation by lactic-acid bacteria increases the acidity which inhibits the growth of food-poisoning and spoilage bacteria · the moisture content is lowered and salt is added to inhibit bacterial and mould growth. The table, right, outlines the stages of production and the equipment needed to produce Edam cheese. Pre-heating The pasteurized milk is heated to a temperature at which the starter-culture can work. Addition of starter culture Starter-culture is added to the milk at the rate of approximately 2 per cent of the weight of milk. The vessel used should be either aluminium or stainless steel. Addition of rennet The rennet should be 1 per cent of the weight of milk. The rennet alters the milk proteins and allows them to form the characteristic curd. Incubation The milk is allowed to stand until it sets to a firm curd. Treatment of the curd The curd is cut into cubes which facilitate the elimination of whey from the gel.

The curd is then cooked at 40°C for a period of twenty minutes which has the action of firming the curd. After cooling, the whey is drained off. The curd is pressed to ensure that most of the whey has been removed, and is then cut to fit the cheese-moulds, and finally pressed with weights. Ripening This is the final stage in the cheese-making process. It is a process which allows the development of gas in some cheeses and the development of flavour. The longer the ripening process the stronger the flavour. Ripening usually takes place in ripening rooms, where the temperature and humidity must be controlled for the optimum development of the cheese. Production stages for Edam-type cheese Ingredients Wax with paraffin wax store at 9°C Refrigerated storage 15.0 Packaging and storage The packaging requirements differ according to the type of cheese produced. Hard cheese, for example, has an outer protective rind which protects the cheese from air, microorganisms, light, moisture-loss or pick-up, and odour pickup. Cheese should be allowed to 'breathe', otherwise it will sweat. Suitable wrapping materials are therefore cheesecloth or grease-proof paper.

Cheese should be stored at a relatively low temperature between 4 and 10°C to achieve a shelf-life of several weeks/months. Soft cheeses are often stored in pots or other containers, often in brine, to help increase their shelf-life of several days/weeks. Selling ice cream from a bicycle Ice cream Ice cream is a frozen mixture which contains milk, sugar, fat, and optional thickeners (e.g. pectin or gelatin), colouring, and flavouring. It may be sweetened and flavoured in numerous ways with nuts, fruit pieces, and natural or artificial flavours and colours. The principles of preservation are: · pasteurization to destroy most micro-organisms and enzymes · freezing to inhibit microbial growth. Pasteurization Pasteurization is carried out by heating to 65°C for a period of 30 minutes. Cooling and beating Ice cream is a complex mix of small ice crystals and air bubbles in a milk-fat/water emulsion. To achieve this, it is necessary to cool the mixture quickly to produce small ice crystals and at the same time incorporate air into the product by beating. Ingredients Freezer 32.0 Ice cream makers are available commercially and work on the following principle.

The mixture is placed in a bowl which is kept at a low temperature (either surrounded by ice and salt, or having been chilled in a freezer). It is then agitated by a manually-operated rotor or by a powered stirrer. At the end of this process the ice cream should be at a temperature of approximately -5°C, and be partly frozen. Packaging and storage The ice cream is usually packaged in plastic, waxed paper, or cardboard containers, and is stored at below -18°C. The storage temperature is important for two reasons: · to maintain the texture of the product · to prevent the growth of micro-organisms. Ice cream may be transported in an insulated box (e.g. for sale from a bicycle). It is especially important to guard against thawing and re-freezing as this will cause changes in texture and mouthfeel, and there is the increased possibility of food poisoning by contaminating food poisoning microorganisms. Suitability for small-scale production In some regions, there is a high demand for dairy products both for traditional and modern items. Much of the technology and machinery necessary for processing is fairly simple, which may at first sight appeal to the would-be processor.

Milk, however, is a highly perishable food and there is a high risk of transmitting food-poisoning bacteria to consumers. It is stressed, therefore, that milk processing of any kind must be done under carefully controlled hygienic conditions. Furthermore, in developing countries, milk processing is often more problematic than in temperate climates, owing to higher temperatures and humidity. Consequently, milk spoils at a faster rate, cheese ripens too quickly, and it is often difficult to ensure adequate cooling conditions. Food Safety Education | For Educators | Competencies | General | Food Processing | Untitled Search: Describe pasteurization. Pasteurization is the process of heat processing a liquid or a food to kill pathogenic bacteria to make the food safe to eat. The use of pasteurization to kill pathogenic bacteria has helped reduce the transmission of diseases, such as typhoid fever, tuberculosis, scarlet fever, polio, and dysentery. It is important to note that foods can become contaminated even after they have been pasteurized. For example, all pasteurized foods must be refrigerated. If the pasteurized food is temperature-abused (e.g., if milk or eggs are not kept refrigerated), it could become contaminated.

Therefore, it is important to always handle food properly by handling it with clean hands, preventing it from becoming contaminated, and keeping it at a safe temperature. How Pasteurization Works Foods are heat-processed to kill pathogenic bacteria. Foods can also be pasteurized using gamma irradiation. Such treatments do not make the foods radioactive. The pasteurization process is based on the use of one of following time and temperature relationships. High-Temperature-Short-Time Treatment (HTST) -- this process uses higher heat for less time to kill pathogenic bacteria. For example, milk is pasteurized at 161°F (72°C) for 15 seconds. Low-Temperature-Long-Time Treatment (LTLT) -- this process uses lower heat for a longer time to kill pathogenic bacteria. For example, milk is pasteurized at 145°F (63°C) for 30 minutes. It is important to remember that the times and temperatures depend on: (1) the type of food and (2) the final result one wants to achieve, such as retaining a food’s nutrients, color, texture, and flavor.

Processes Used to Pasteurized Foods Flash Pasteurization - Involves a high-temperature, short-time treatment in which pourable products, such as juices, are heated for 3 to 15 seconds to a temperature that destroys harmful micro-organisms. After heating, the product is cooled and packaged. Most drink boxes and pouches use this pasteurization method as it allows extended unrefrigerated storage while providing a safe product. Steam Pasteurization - This technology uses heat to control or reduce harmful microorganisms in beef. This system passes freshly-slaughtered beef carcasses that are already inspected, washed, and trimmed, through a chamber that exposes the beef to pressurized steam for approximately 6 to 8 seconds. The steam raises the surface temperature of the carcasses to 190° to 200° F (88° to 93°C). The carcasses are then cooled with a cold-water spray. This process has proven to be successful in reducing pathogenic bacteria, such as E. coli O157:H7, Salmonella, and Listeria, without the use of any chemicals. Steam pasteurization is used on nearly 50% of U.S. beef.

Irradiation Pasteurization - Foods, such as poultry, red meat, spices, and fruits and vegetables, are subjected to small amounts of gamma rays. This process effectively controls vegetative bacteria and parasitic foodborne pathogens and increases the storage time of foods. The Effect of Pasteurization on Nutrients and Flavor Pasteurization can affect the nutrient composition and flavor of foods. In the case of milk, for example, the high-temperature,short-time treatments (HTST) cause less damage to the nutrient composition and sensory characteristics of foods than do the low-temperature, long-time treatments (LTLT). Examples of Foods that Are Commonly Pasteurized Whole Eggs Removed from Shells and Sold As a Liquid - Large quantities of eggs are sold to restaurants and institutions out of the shell. The yolk and whole-egg products are pasteurized in their raw form. The egg white is pasteurized in its raw form if it is sold as a liquid or frozen product. Dried Eggs - If eggs are sold dried, the egg white with the glucose removed is normally heat-treated in the container by holding it for 7 days in a hot room at a minimum temperature of 130°F (54°C).

Whole Eggs Pasteurized in the Shell - Traditionally, eggs sold to customers in the shell have not been pasteurized. However, new time/temperature pasteurization methods are making this possible. Egg whites coagulate at 140°F (60°C). Therefore, heating an egg above 140°F would cook the egg, so processors pasteurize the egg in the shell at a low temperature, 130°F (54°C), for a long time, 45 minutes. This new process is being used by some manufacturers, but it is not yet widely available. Pasteurizing eggs reduces the risk of contamination from pathogenic bacteria, such as Salmonella, which can cause severe illness and even death. Pasteurized eggs in the shell may be used in recipes calling for raw eggs, such as Caesar salad, hollandaise or bé arnaise sauces, mayonnaise, egg nog, ice cream, and egg-fortified beverages that are not thoroughly cooked. Milk - Pasteurization improves the quality of milk and milk products and gives them a longer shelf life by destroying undesirable enzymes and spoilage bacteria.

For example, the liquid is heated to 145°F (63°C) for at least 30 minutes or at least 161°F (72°C) for 15 seconds. Today, many foods, such as eggs, milk, juices, spices and ice cream,are pasteurized. Sometimes higher temperatures are applied for a shorter period of time. The temperatures and times are determined by what is necessary to destroy pathogenic bacteria and other more heat-resistant disease-causing microorganisms that may be found in milk. The liquid is then quickly cooled to 40°F (4°C). Other liquids, such as juices, are heat-processed in a similar manner. Temperatures and times vary, depending on the product and the target organism. Other types of milk pasteurization Ultrapasteurization - This involves the heating of milk and cream to at least 280° F (138° C) for at least 2 seconds, but because of less stringent packaging, they must be refrigerated. The shelf life of milk is extended 60 to 90 days. After opening, spoilage times for ultrapasteurized products are similar to those of conventionally pasteurized products.

Ultra-High-Temperature (UHT) Pasteurization - typically involves heating milk or cream to 280° to 302°F (138° to 150°C) for 1 or 2 seconds. The milk is then packaged in sterile, hermetically-sealed (airtight) containers and can be stored without refrigeration for up to 90 days. After opening, spoilage times for UHT products are similar to those of conventionally pasteurized products. SOURCE: Adapted from the A to Z Guide for Food Safety. The complete publication is available on-line at: If you have questions, contact Dr. Angela Fraser , Associate Professor/Food Safety Education Specialist, Clemson University, Clemson, SC. Clemson University is an AA/EEO employer and does not discriminate against any person or group on the basis of age, color, disability, gender, national origin, race, religion, sexual orientation, or veteran status. © 2012 Department of Food, Nutrition, and Packaging Science Clemson University

Question: Which one of these people is most associated with heat treatment of milk?
Answer: Louis Pasteur