Lecture+17+thermaldestruction+and+water+activity+_color_

Lecture+17+thermaldestruction+and+water+activity+_color_ -...

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WATER ACTIVITY FST104 FEBRUARY 22, 2012 D value (time): Decimal reduction time Δ time resulting in a 10-fold change in viable cells Survival Curve Z value (temperature): Δ T resulting in a 10-fold change in D F value (time): D x number of logs reduction temperature log (D value) Z value Decimal Reduction Curve
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Below are survival data for Clostridium botulinum endospores held at 240°F. Graphically determine the D240°F for C. botulinum in this medium. Time Held (minutes) Number of Survivors 5 2.2 x 10^7 10 6.5 x 10^6 15 2.3 x 10^6 20 9.1 x 10^5 25 1.2 x 10^5 Practice problem #1 Answer: 10 minutes
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