BIOL241 Final: Unit 10

• School: University of Waterloo
• Department: Biology
• Course: BIOL241
• Professor: Barbara Butler

Document Summary

Microorganisms and foods a number of aspects to consider: spoilage of foodstuffs by (usually) nonpathogenic microorganisms methods of food preservation use of microorganisms in food production foodborne disease-causing microorganisms (i) food spoilage: Water content and availability is important water activity (aw): a measure of available water (see p. 170-71, wessner et al. ) water activity = vp of air in equilibrium with substance or solution/ vp of pure water. Think vp of food item/ solvent (so water) Vp pure water is one, anything other less than 1. Tightly absorbed in surface of food and think jellies water is there but not available for microbes. Gram positives more resistant to low water levels. Molds etc. can deal with low water better than bacteria can. Has to come in contact with food and foor provide an environment suitable. Some microbes aren"t pathogenic (pink are), most just spoilage. Ones for meats often come from gastrointestinal tract.