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Morgan.liberatore
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thermal processing is specifically designed to:
 make the product safe and shelfstable
 reduce the number of microorganisms of public health concern to a statistically small level (botcook)
 suppress the growth and activity of spoilage microorganisms

what must one first understand to successfully apply thermal processing?
microbial thermal destruction kinetics

what is the general form of the order of reaction for a single component?

what is the zero order of the order of reaction equation?
m=0, so

what is the first order of the order of reaction equation?
m=1, so

what is the second order of the order of reaction equation?
m=2, so

for thermal destruction of microbes, enzymes, and nutrients generally follow which order reaction rate?
first order reaction rate

what is the D value?
 the decimal reduction time
 heating time at any given temperature which results in 90% destruction of the microbial population, or one decimal reduction in the surviving population

how is the D value obtained from the graph?
the time required for the curve to pass one log cycle

what is the thermal death time?
 time in minutes required to destroy a microbial population at any given temperature
 used exclusively in process calculations

what does death time depend on?
initial population

what is the slope of the TDT line?

what does z represent mathematically?
the negative reciprocal slope of TDT or D value curve

what is the sterilization reference temp?
250°F or 121°C

what is the pasteurization reference temp?
 150°F or 180°F
 (wtf does that mean??)

how is the TDT tube method done?
 small glass tubes are flame sealed with small samples
 heated for various times at constant temp
 either survivors are counted, or tubes are tested for positive or negative

what are the advantages of the tube method?
 simple and inexpensive
 growth can be observed in a tube
 easy subculturing
 heating lags are minimized if tubes are very small

what is the TDT can method?
 use special TDT cans (D=208, H=0.006)
 mechanical closures
 small steam retorts
 these can be used for both cans and tubes
 heating and cooling performed in a special "mini retort"

what are the advantages of the TDT can method?
 processing conditions simulate commercial operations
 spoilage by gas formers readily detected by can swelling
 faster and easier sealing than TDT tubes

what are the disadvantages of the TDT can method?
 heating and cooling lag compensation needed
 need special retort
 subculturing more difficult than with tube
 post processing contamination due to leaks

what is the TDT thermoresistometer method?
 three chambers (sample introduction, heating, subculturing)
 carriers transfer samples
 steam controlled temperature
 precise time (0.001min)
 small sample size (1/100mL)
 no lag
 six replicates and statistical approach
 most probable number of survivors

what are the advantages of the thermoresistometer method?
 no lag
 instantaneous heating and cooling
 short times possible (6 sec with less than 0.5% error)
 high temp
 automatic subculturing
 less labor
 operation is simple

what are the disadvantages of the thermoresistometer method?
 high cost
 direct inoculation not possible

what is MPN?
most probable number  per given unit (per mL, per container, etc)

how is MPN calculated?
 where a=amount of sample (per can or per mL)
 n=total number of replicates
 q=number of negative samples

what is the MPN technique based on?
 statistical approach
 makes use of logarithmic order of death
 can be used for both initial count and final counts
 used in Stumbo's thermoresistor approach for D (accurate and sophisticated technique)

what does mean?
means F at reference temp T (250°F) is 0.2min (F_{o}) and z value = 18°F

