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BIOL 345 Set 6 Canning.pdf

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University of Waterloo
BIOL 345
Barbara Butler

Can1 Canning: • foods preserved by heat sterilization within a hermetically sealed container • invented by Appert, others contributed (e.g., Durand & de Heine, 1810; use of metal containers) • useful process, but risky until Estes & Meyer (1922) & others worked out time-temperature relationships → non-empirical thermal processing protocols • late 19th-early 20th C: canning industry plagued by periodic outbreaks of botulism • present-day: botulism is extremely rare • almost never associated with commercially-produced canned products 12D concept: a “process lethality” requirement, e.g., in the canning industryan2 • idea is enough heat (or other process) must be applied to reduce 1012 spores → 1 spore/mL or g • reality: starting population never approaches 1012 # 101 o 2 extrapolation of f hypothetical s 10 survivor curves u 6 illustrating 12D r reduction vi 10 vi 0 n g if 1 botulinum spore per can, p 60- there’d be a 1 in 1012 chance o of it surviving r or 1 can in 1012 would have e 10- a spore in it s 12 process time p example: D = 0.21 min for C. botulinum at 121ºC; assume each can contains 1 spore r F0 = D121(log a – log b) = 0.21(log 1 – log 10-12) = 0.21 x 12 = 2.52 min i.e., processing for 2.52 min would reduce it to 1 spore per 1012 cans it “botulinum cook” Heat resistance of endospores of some thermophilic & mesophilic Can3 spoilage organisms: bacterium D121ºC value Geobacillus stearothermophilus 4.0 - 5.0 Thermoanaerobacterium 3.0 - 4.0 thermosaccharolyticum Desulfotomaculum nigrificans 2.0 - 3.0 Clostridium sporogenes 0.10 - 1.5 Bacillus coagulans 0.01 - 0.07 Loading... C. botulinum (**pathogen**) 0.10 - 0.20 thermophilic; mesophilic (after Jay, 2000) • aim to achieve a ~5D reduction in (non-C. botulinum) sporeformers to avoid spoilage • products distributed to warm climates may require more severe processing to deal with thermophilic sporeformers Can4 Canning: factors that determine processing time and temperature: • material of which container is made • size, shape of container • consistency of contents • conduction • convection • does product change during processing? • rotation, agitation of container • initial temperature of food • initial temperature of retort cooker • rate of cooling • number and type of microorganisms (bacteria) anticipated Can4a commercial retorts Technologies Incorporated, farmer canning India) Loading... m) retort pouched smoked preparation of vegetable soup for website)Ent Fish Company Ltd. (B.C.)’3rd ed)tt et al.,1996. Microbiology, aseptic processing and packaging: Can4b
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