23 microbiology of food
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Created by:
catheenewyen on December 12, 2010
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39 terms
Terms | Definitions |
|---|---|
 intrinsic factors | food composition. pH. presence/availability of water. oxidation-reduction potential. physical structure. presence of antimicrobial substances |
| putrefaction | proteolysis and anaerobic breakdown of proteins, producing foul-smelling amine compounds |
| lower water activity inhibits microbial growth | true |
| water activity is lowered by | drying, addition of salt/sugar |
| microorganisms that prefer high osmotic pressure | osmophilic |
| microorganisms that prefer low water activity | xerophilic |
| increased surface area promotes microbial growth | true |
| outer skin of vegetables and fruits slows microbial growth | true |
| extrinsic factors | temperature (lower temp retards microbe growth). relative humidity (higher levels promote growth). atmosphere (oxygen promotes growth) |
| food spoilage | caused by growth of microbes in food. toxins sometimes produced |
| ergotism | toxic condition caused by growth of fungus in grains |
| aflatoxins | carcinogens produced in fungus-infected grains and nut products |
| fumonisins | carcinogens produced in fungus-infected forn |
| algal toxins | contaminate fish and shellfish |
| removal of microorganisms | usually achieved by filtration. |
| low temperature | refridgeration retards but doesnt stop microbe growth. can still cause spoilage |
| high temperature procedures | canning- food heated in special containers but doesnt kill all microbes pasteurization- kills pathogens and reduces number of spoilage organisms |
| dehydration | eliminates bacterial growth. free-water loss and increase in solute concentration |
| GRAS | chemical agents "generally recognized as sage" |
| used for surfaces of food handling equipment. does not penetrate foods | UV radiation |
| uses ionizing radiation to extend shelf life. kills microbes in moist foods by producing peroxides from water | radappertization |
| electrically generated electrons, turned on only when needed and does not penetrate food as deeply as radappertization (gamma) | electron beams |
| bacteriocins | bactericidal proteins active against related species. |
| bacteriophages | kills microbes and were approved for use on ready to eat meats |
| two primary types of food-borne diseases | food-borne infections and food intoxications |
| food-borne infection | ingestion of microbes, followed by growth, tissue invasion or release of toxins. found in raw foods |
| examples of food-borne infections | salmonellosis: contaminated meats poultry or eggs listeriosis: affects pregnant women and immunocompromised individuals. e.coli: diarrhea |
| food-borne intoxication | ingestion of toxins in foods in which microbes have grown. includes staph food poisoning, clostridium, perfringens food poisoning, and bacillus cereus food poisoning |
| detection of food-borne pathogens | must be rapid and sensitive methods include: culture techniques, immunological techniques, molecular techniques |
| PulseNet | est by centers for disease control. -uses electrophoresis to determine DNA patters for pathogens. |
| FoodNet | active surveillance network used to follow 9 major food-borne diseases. traces course and cause of infection in days instead of weeks |
| major fermentations used are | lactic, propionic, ethanolic |
| fermented milk products rely on | lactic acid bacteria |
| cheese production | milk>curd>cheese |
| producing alcohol | must-juice from crushed grapes mashing- hydrolysis of carbs by adding water and heating wort- clear liquid with fermentable carbs |
| beers and ales | malt- germinted barley grains having activated enzymes mash- malt after being mixed with water hops-provide flavor and help in clearing word bottom yeasts- used in beer top yeasts- used in ales lager- aged beer. CO2 added at bottling |
| spirits | begins with sour mash. after fermentation, distilled to concentrate alcohol |
| bread production | involves bakers years under aerobic conditions maximizing CO2 production which leavens bread. can be spoiled by bacillus |
| probiotics | microbes added to diet to provide health benefits |
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