At 4c combined w other spoilagelipolytic

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’at ≤ 4C-combined w/ other preservation^putrefaction spoilage/lipolytic spoilage/psychrotrophic bacteria survive/ lactic acid bacteria- cannot survive-souring of raw milk 3) 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&most spoilage causing MOs, free from viable forms of MOs (including spores), some heat-resistant spores must survive;^X able to germinate at rm. Packaged in temp& pressure-resistant container, hermetically sealed: impermeable to transmission gases, liquids ad MOs/ over 2yrs w/o refrigeration / Ultra high temperature - injection of hot steam under pressure ( 140- 150C ) for short time ( 4- 6s), followed by immediate cooling/ Aseptic packaging - shelf-life>=6 mons w/o refrigeration aseptically placed fd into pre-sterilized containers and sealed.Selecting heat treatment-sufficient heat, mildest HT that guarantees freedom from pathogens and toxinsMilk processing: #3 clarification, homogenization, pasteurization Tetra Pak : polyethylene-protects against outside moisture; polyethylene- adhesion layer; polyethylene-seals in the liquid Tin cans : withstand high tem&pressure, hard to break, use lacquers to mini food reaction. Retort pouches : heat penetrates faster, nutrient retained, must be packaged Glass jar : resistant to reaction with food; transparent, thermal shock; Plastic : hermetically sealed(commercial ster.); Thermal Death Curves: MOs r X killed instantaneously, Microbial death- logarithmic order death : under constant thermal conditions the same% of microbial population will be destroyed in a given time interval, regardless of the surviving population; Survivor curve/thermal death rate curve (TDRC): D-value (decimal reduction time): time (in min) at a particular temp(C)required to kill 90% of microbial population; high->harder to kill/increase temp, lower D-value Thermal death time curves (TDTC): time required for destruction of a microbe under specific conditions at diff temp -z-value (C): resistance of an MO to diff temp, allows comparison of heating processes at diff temp & F-value (min) : lethality of heat treatment, min required to kill MOs at 121C, capacity of heat treatment to sterilize/ Margin of safety (MS) : mini. possibility of viable survivors of C. botulinum spores 1.Low acid - uses 12D thermal process=12 log cycle reduction=can kill 10 12 MOs, large MS, D-value↓as temp↑,time required for thermal process depends on D-value at certain temp 2.Acidic acid - 5D bc C. botulinum cant grow in ac fd ph<4.6//if 10000 Mos present, if 3D is used then we have 10000-1000=10. Determine if C.b have been destroyed? -Inoculated pack studies- Clostridium sporogenes PA3679 (putrefactive anaerobe)- more heat resistant than C. b Location Cold point : depends on mechanism of heat transfer, consistency of fd (viscous L or non- viscous L)&chem compo(fat,protein), slowest heating part of the food/heating by Conduction : solid fd; heat transfer: molecule to-molecule in straight line (cold pt in middle) Convection: heat transfer by fluid motion non-

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