FST 10 Lecture Notes - Lecture 17: Ozonolysis, Radiography, Sodium Chloride
18 Sep 2017
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Class: fst 010 topic: food preservation, fermentation, spoilage. Freezing: stops growth, impedes chemical changes: high temperature kills microorganisms. Aseptic packaging: sterilizes product: other important ways that foods are preserved are made safe to consume are by controlling water and acid content. Water content: originally scientists tried to measure the moisture content as a % Isn"t water % also important as with more water there"s more area/resources for bacteria to live in? which can support the growth of bacteria, yeast, and mold. Low aw usually means bacteria (especially pathogens) won"t grow. C. botulinum doesn"t grow in foods w/ water activity < 0. 93. Not the same thing as a food"s moisture content. Moist foods generally have greater water activity than dry foods. A variety of foods may have exactly the same moisture content and yet have quite different water activities: to lower water activity we can, dry the food. Ex: grapes, plums, sun-dried tomatoes, beef jerky, salami: add salt.
