BIO 3124 Lecture Notes - Lecture 9: Clostridium, Thermal Death Time, Ultra-High-Temperature Processing
16 Oct 2016
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Document Summary
Killing or removing all forms of microbial life (including endospores: the method most commonly used for sterilization is the use of heat. Thermal treatment which kills clostridium botulinum spores, the causative agent of botulism, in canned foods: does not kill spores of thermophiles which are not pathogenic. Modes of heat sterilization - do(cid:374)"t (cid:374)eed to (cid:373)e(cid:373)orize (cid:374)u(cid:373)bers! Kills microbes by denaturing proteins: boiling (100oc, pasteurization (65 - 140oc, autoclave (121oc) Kills by oxidation: pasteur oven (121 - 250oc) Dry heat requires higher temp and longer exposure. 10 minutes at 100oc at sea level. Endospores and some viruses are not destroyed: hepatitis virus: can survive up to 30 minutes, endospores: can survive for periods of 20 hours or more. Kills pathogenic agents without affecting the taste of the food. Classical pasteurization: 63oc for 30 seconds. Htst pasteurization: 72oc for 15 seconds. Uht pasteurization: 140oc for 3 sec. under vacuum. Main purpose is to lengthen shelf life.
