FOS2001 Module 4 Lesson 15
FOS2001 Module 4 Lesson 15 FOS 2001
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This 3 page Class Notes was uploaded by Haley Kairab on Tuesday April 12, 2016. The Class Notes belongs to FOS 2001 at University of Florida taught by Dr. Agata Kowalewska in Spring 2016. Since its upload, it has received 12 views. For similar materials see Man's Food in Nutrition and Food Sciences at University of Florida.
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Date Created: 04/12/16
FOS2001 Module 4 Lesson 15 Food Preservation Microbial Food Spoilage Due to Temperature, pH, or Air • Food that is left out and exposed to high temperatures is conducive to microbial food spoilage • Microorganisms that cause food to spoil because of temperature: ◦ Psychrophiles found in milk and dairy products; thrive in temperatures from 2060 degrees F; can grow in temperatures up to 100 degrees F. ◦ Mesophiles found in bread, grains, dairy products, meats; optimum growth temperature is 86 degrees F; can grow in temperatures from 41 130 degrees F. ◦ Thermophiles found in areas with high temperatures (like water in naturally occurring hot springs or compost piles); grow in high temperatures from 90167 degrees F. • The pH level of food also adds to microbial food spoilage ◦ The higher the pH level of food, the less acidic it is ◦ Foods with pH below 4.5 and more susceptible to spoilage from yeast and molds than from bacteria • The last contributing factor to microbial food spoilage is air ◦ Some microorganisms need oxygen to grow (aerobic) ◦ An anaerobic organism does not need oxygen ◦ Depriving an aerobic microorganism of oxygen Molds and Food • Seeing mold on foods is not always a sign of spoilage ◦ Some foods (like Brie and Camembert cheese) use mold as a part of manufacturing process • But not all molds are safe ◦ Molds on foods that aren't used for manufacturing process should not be eaten ◦ Symptoms can range from allergic reactions or respiratory problems to extreme illness from being poisoned by mycotoxins • Molds are not bacteria, but seeing moldy food is a sign of spoilage and there are high odds that there is unseen bacteria • Discarding the moldy part of food and keeping the rest is only acceptable for ◦ Hard cheeses ◦ Firm fruits and vegetables Chemical and Physical Spoilage • Chemical spoilage refers to spoilage that occurs as a result of chemical changes in food • These changes can be caused by: ◦ Water loss ◦ Enzymes breaking down the food such as fruit and vegetable ripening, muscle rigor, etc. ◦ Enzymatic processes that result in browning • Physical spoilage occurs when food is exposed to: ◦ Heat, as when food is left unrefrigerated ◦ Cold, as when foods show ice crystal damage ("freezer burn"), which will not make you sick but will make food inedible ◦ Light, which can deteriorate the quality of food Food Additives • The substances added to food to maintain quality and preserve it have changed from the time when sugar was added to fruit to preserve it, or meat being cured with salt • Food additives now consist primarily of chemicals • Sequestrants are preservatives that prevent natural metal ions from negatively affecting food's stability and quality ◦ Ex/ that you might find on food labels: sodium gluconate, potassium gluconate, or EDTA • Antioxidants are substances that prevent oxygen from changing the flavor or color of food ◦ Ex/ of antioxidants you can find on food labels are BHA and BHT • Antimicrobial agents, like benzoate and sorbate, control microbial growth in food • Acidulants are chemicals that add acidity to food to improve taste or adjust its pH level ◦ Ex/ citric acid and phosphoric acid • Gums are used to achieve the desired consistency of foods, or to act as a thickening agent ◦ Pectin (a plant material derived from citrus peels or sugar beets) is widely used to give jams, jellies and yogurt products their consistency • Humectants hold water in food and help to maintain texture ◦ Ex/ Glycerine • Emulsifiers permit distribution of tiny particles of one liquid within another liquid to keep immiscible liquids in the food together ◦ Ex. Lecithin Regulating Food Additives • Food additives are evaluated and regulated by the U.S. Food and Drug Administration (FDA). The FDA must approve additives for use in specific foods before they can be added to commercially sold food ◦ Substances that are GRAD (generally recognized as safe) like spices, are excluded from FDA approval • Particular attention is paid to additives listed on meat and poultry products ◦ Additives in these product (used to preserve or enhance color) must be itemized on the label • Spices added to flavor and not to provide nutritional value do not need to be listed separately • Before an additive can be approved, its intended usage is reviewed ◦ If it is determined that an accepted food additive is unsuitable for the intended use then it will not be approved
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