presence/availability of water.
presence of antimicrobial substances
proteolysis and anaerobic breakdown of proteins, producing foul-smelling amine compounds
lower water activity inhibits microbial growth
water activity is lowered by
drying, addition of salt/sugar
microorganisms that prefer high osmotic pressure
microorganisms that prefer low water activity
increased surface area promotes microbial growth
outer skin of vegetables and fruits slows microbial growth
temperature (lower temp retards microbe growth).
relative humidity (higher levels promote growth).
atmosphere (oxygen promotes growth)
caused by growth of microbes in food.
toxins sometimes produced
toxic condition caused by growth of fungus in grains
carcinogens produced in fungus-infected grains and nut products
carcinogens produced in fungus-infected forn
contaminate fish and shellfish
removal of microorganisms
usually achieved by filtration.
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
eliminates bacterial growth. free-water loss and increase in solute concentration
chemical agents "generally recognized as sage"
used for surfaces of food handling equipment. does not penetrate foods
uses ionizing radiation to extend shelf life. kills microbes in moist foods by producing peroxides from water
electrically generated electrons, turned on only when needed and does not penetrate food as deeply as radappertization (gamma)
bactericidal proteins active against related species.
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
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.
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
est by centers for disease control.
-uses electrophoresis to determine DNA patters for pathogens.
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
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
begins with sour mash. after fermentation, distilled to concentrate alcohol
involves bakers years under aerobic conditions maximizing CO2 production which leavens bread.
can be spoiled by bacillus
microbes added to diet to provide health benefits