← set 2 Test
5 Written Questions
5 Matching Questions
- bacillus cereus
- Lactic acid
- least sensitive
- More sensitive
- a Range of radiation sensitivity: clostridium and bacillus (spores)
- b Organic acids-often naturally produced in fermented foods. Foods naturally preserved. (cheese)
- c (species) bacteria that will grow in food. Secrete toxin. Causes vomiting, diarrhea. Source: soil bacteria in dust.
- d Range of radiation sensitivity: Pseudomonas
- e peak efficiency of aerobic microbes in reducing organics. Secondary treatment.
5 Multiple Choice Questions
- permitted for some foods. Will sterilize but can/will cause chemical changes in food. Creates peroxides that degrade proteins. End product: NH3 and amines. Degrade fats, short chain fatty acids. Was concern might create carcinogen.
- canning temperature needed for high acid foods (pH<4.5). Kills all vegetative cells. If spores survive, can't germinate at low pH
- (genus) bacteria associated with unpasteurized cheese and "pre-cooked meats"-hot dogs, deli meats
- chemicals added primarily to stop chemical oxidation. Stop oxidation of fats that yields short chain fatty acids (odor, taste problems). May also have anti-microbial activity.
- end product of anaerobic sludge digester. Organics will be fermented or organic acids + carbon dioxide. It is then converted to _________ by methanogens.
5 True/False Questions
competition → pathogens are trapped in floc. They get killed by _________: intestinal microbes are not well adapted to this environment. Lose out by ____ for nutrients to "good bugs'
anaerobic sludge digester → take care of solids leftover from secondary treatment. Rate of digestion is slower than secondary, metaoblism is less efficient, but faster if warmer. Heated to 95-100F. Does reduce final volume of solid, Some molecules can only be decomposed by this. End product: carbon dioxide and METHANE
120C → canning temperature needed for low acid food (pH>4.5). Spores will germinate at 100C, so need to use pressure and hotter water.
refrigeration → permitted for some foods. Will sterilize but can/will cause chemical changes in food. Creates peroxides that degrade proteins. End product: NH3 and amines. Degrade fats, short chain fatty acids. Was concern might create carcinogen.
chlorine → Disinfection after secondary treatment depends on next use. Bleach, compressed gas. Very effective disinfectant that oxidizes everything such as proteins. Use at the end, inactivated by excess organics. Don't want to kill beneficial decomposers