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Bio Chapter 30
| Question | Answer |
|---|---|
| Foods intentionally altered during production by carefully controlling the activity of bacteria, yeasts, or molds are called | Fermented foods |
| Undesirable biochemical changes in food is | food spoilage |
| Characteristics of the food itself—such as water availability, acidity, and nutrient level—are called | Intrinsic factors |
| is used to indicate the amount of water available in foods. By definition, pure water has an aw of 1.0. Most fresh foods have an aw above 0.98 | Water activity |
| Foods vary in terms of how much _____ is accessible to microorganisms. Fresh meats and milk, for example, have plenty of_____ to support the growth of many microbes. | Water |
| Many bacterial species, including most pathogens, are inhibited by _____ conditions and cannot grow at a pH below 4.5. | Acidic |
| Many bacterial species, including most pathogens, are inhibited by acidic conditions and cannot grow at a pH below 4.5. An exception is the ______ bacteria, which can grow at a pH as low as 3.5. | Lactic Acid |
| ____ can grow at a lower pH than most spoilage bacteria, so some acidic foods eventually become moldy | Fungi |
| Caused by Clostridium botulinum. Produces botulinum toxin, the most deadly neurotoxin on the earth | Botulism |
| ______ often spoil foods because many can synthesize essential nutrients and multiply in many environments, including refrigeration | Pseudomonas |
| Organisms requiring particular vitamins cannot grow without certain _____ | Nutrients |
| Rinds, shells, and other coverings help protect foods from invasion by microorganisms. Eggs, for example, retain their quality much longer with intact shells. | Biological Barriers |
| Some foods contain natural ___ that help prevent spoilage. Egg white, for instance, is rich in lysozyme. If lysozyme-susceptible bacteria breach the protective shell of an egg, they are destroyed by lysozyme before they can cause spoilage. | Antimicrobial Chemicals |
| Environmental conditions under which a food is maintained—such as temperature and atmosphere—are called _____ | Extrinsic Factors |
| These can greatly affect the extent of microbial growth on food. | Extrinsic Factors |
| The ____ affects the growth rate of microorganisms. At low temperatures above freezing, many enzymatic reactions are either very slow or non-existent, with the result that microorganisms multiply slowly, if at all. | Storage Temperature |
| Microorganisms that grow on refrigerated foods are most likely psychrophiles or psychrotrophs, such as some members of the genus Pseudomonas. | What organisms thrive at low temperatures? |
| At _____ temperatures, water crystallizes/becomes solid, is then inaccessible, stops microbial growth | Freezing |
| Obligate aerobes cannot grow under conditions that exclude O2; this may allow anaerobes to grow | Atmosphere |
| ____ inhibit growth of many spoilage organisms, foodborne pathogens | Fermented food acids |
| The tart taste of yogurt, pickles, sharp cheeses, and some sausages is due to the production of ____ | Lactic Acid |
| obligate fermenters that characteristically produce lactic acid as an end product of their metabolism. Some also produce flavorful and aromatic compounds | Lactobacillus, Lactococcus, Streptococcus, Leuconostoc, and Pediococcus |
| sterile in cow’s udder, but rapidly contaminated during milking and handling Lactic acid species residing on udder introduced If milk unrefrigerated, will ferment lactose | Milk |
| Removal of primary sugar and reduction in pH inhibits growth of many other microbes Lower pH causes milk proteins to coagulate or curdle, also sours the flavor | Milk |
| Cottage cheese simpler to make, starter cultures (typically Lactococcus cremoris, L. lactis) ferment milk, coagulate proteins Curd is heated, cut into small pieces, liquid drained | Cheese |
| The initial steps of ripened cheese production are the same as those of cottage cheese, except the ____ rennin is added to the fermenting milk to speed protein coagulation | Enzyme |
| milk evaporated to concentrate slightly, then inoculated with Streptococcus thermophilus and Lactobacillus delbrueckii subspecies bulgaricus | Yogurt |
| traditional is product of fermentation by Lactobacillus acidophilus; sweet is not fermented, but instead culture is added immediately before packaging | Acidophilus milk |
| any undesirable changes in food | Food spoilage |
| Results from metabolites with undesirable tastes/odors. Generally notharmful, since usually not human pathogens. Most pathogens grow optimally near 37°C.Nutrients in foods usually not suitable for their growth.Non-pathogens can easily outgrow pathogens | Foodspoilage |
| Wide variety including Rhizopus, Alternaria, Penicillium, Aspergillus, and Botrytis spoil food | Common Spoilage Fungi |
| Can grow in acidic and low-moisture environments, so fruits and breads more likely spoiled by fungi than bacteria Aspergillus flavus grows on peanuts, other grains, produces potent carcinogen aflatoxin | Common Spoilage fungi |
| Bacillus, Clostridium species problematic; _____ survive cooking, sometimes canning | Endospores |
| Consumption of pathogen or toxin produced by pathogen Despite strict controls in U.S., millions of cases annually Vast majority preventable with proper storage, sanitation, and preparation | Foodborne Intoxication/ Food poisoning |
| Deadly paralytic disease caused by neurotoxin produced by anaerobic Gram-positive rod Clostridium botulinum Growth, toxin may not noticeably change food | Botulism - foodborne inxtoication |
| Consumption of *exotoxin* produced by microorganisms (toxin not the organism itself) | Foodborne intoxication |
Created by:
cshelly