A food contains three type of heat resistant microorganisms P,Q and R with z values of 11,9 and 14 °c respectively . for 6 log cycle reduction of microorganisms, the processing time (F123) of a food at 121°c is 1.0, 1.1 and 0.9 minutes respectively. the time required for 1 cycle reduction( D121) of the microorganism is:
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Answer:
Heat is lethal to microorganisms, but each species has its own particular heat tolerance. During a thermal destruction process, such as pasteurization, the rate of destruction is logarithmic, as is their rate of growth. Thus bacteria subjected to heat are killed at a rate that is proportional to the number of organisms present. The process is dependent both on the temperature of exposure and the time required at this temperature to accomplish to desired rate of destruction. Thermal calculations thus involve the need for knowledge of the concentration of microorganisms to be destroyed, the acceptable concentration of microorganisms that can remain behind (spoilage organisms, for example, but not pathogens), the thermal resistance of the target microorganisms (the most heat tolerant ones), and the temperature time relationship required for destruction of the target organisms.