FNH-CHEAT-SHEET.pdf - Causes of food deterioration...

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Causes of food deterioration: time/physical stress or abuse/reaction with O2or light/ gain or loss in moisture/inappropriate temp/ MOs/ food enzymes & other chemical rxns within the food itself/ infestation by parasites, insects and rodentsPerishable foods- no/minimally processed, shelf life less than 60 daysSemi-perishable- 2-6 mos with some preservationShelf stable- more than 6 mos w/o refrigeration- Food has shelf life less than 90 days must indicate in labelMOs classification:bacteria- fast growing/vegetative cells are active/sporesare dormant, yeast: slower growth but more tolerant, mould: even more tolerant/produce toxins, viruses: agents of food become borne disease but do not cause food spoilage(Function: good/bad/ugly)Psychrophiles:0-18C, psychrotrophs:-5 to 35C, mesophiles: 10-45C, thermophiles: 50 to100CAerobic/anaerobic/facultative anaerobeEnzymatic browning:polyphenol+O2(polyphenol oxidase)-> brown pigmentsPreservation: minimize deterioration, eliminate potential microbiological harm to the consumer, maintain quality and nutritional value while producing a safe product ex. (old->more noticeable changes in food) dehydration, smoking, fermentation, sweetening/(modern) canning, freezing, UHT, irradiationRancidity:improper storage repeated exposure to high temp. –oxidative: double bonds +oxygen -> product… off-flavours, carcinogenic compounds ex. UFA/PUFA + heat,light,O2-> hydroperoxides-> OH, ketones, aldehydes), hydrolytic/lipolytic(cleavage of bond linking FA to glycerol -> (lipase enzymes)releasing free FAs) reducing rate of oxidative rancidity: proper storage and packaging, limit repeated exposure to high temp, addition of anti-oxidantThermal processing: controlled processes using heat 1) Blanching-(mild-intensity heat process) expose foods to boiling and stream for a short period of time->inactivate endogenous enzyme, drive off O2and other gases, not extending shelf-life2) Pasteurization- for food that consume within a short period of time (moderate heating)LTLT (30-40 mins @ 60C); HTST (flash past. 15s @ 72C)Low-acid foods: Destroy/inactivate disease causing (pathogenic) MOs & viruses,Acid food (not a source of pathogens): destroy spoilage-causing MOs & enzyme (E.coli 0157:H7) extended product shelf life durable life date” at ≤ 4C (refrigeration) – combined with other preservation but putrefaction spoilage/lipolytic spoilage/psychrotrophic bacteria survive/lactic acid bacteria- cannot survive- souring of raw milk3) Commercial sterilization- (Botulinum cook- kills Clostridium botulinum: strict anaerobe, grows well in low acid foods, present everywhere, produces neurotoxin)high-intensity heating (req. min 121C moist heat for 15 mins) “canning” destroy both disease causing and most spoilage causing MOs, free from viable forms of MOs (including spores), some heat-resistant spores must survive; but not able to germinate at rm. Temp for at least 6mos- Packaged in temp & pressure-resistant container, hermetically sealed:impermeable to transmission gases, liquids ad MOs have a shelf life over 2 years w/o refrigerationUltra high temperature

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