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— A general solution is obtained for transient temperature distributions in a finite cylinder by applying several integral transformations to heat conduction equation when it is subjected to time variable surface temperatures. From this general solution, various formulas for temperature distributions are derived for five different surface temperature‐processing time relationships. By using these derived formulas, we obtain formulas for these two parameters: slope indices and intercept coefficients of heating or cooling curves of cylindrical cans of conductive food. Expressions are also derived for estimating sterilizing values during a come‐up period of the heat process and also during the sinusoidal fluctuation of retort temperature.

SUMMARYThe kinetics of thermal inactivation of peroxidase were found to he first‐order for the range of temperatures 85–100°C. The experimental activation energy was 25.1 kilocalories per mole; free energy change, 27.0–27.5 kilocalories per mole; and entropy change, a negative 7.39–7.89 calories per mole degree. This indicated that the transfer of energy was extremely slow or the activated molecule was actually more rigid than the native molecule, the latter being more likely than the former. No regeneration occurred when peroxidase had been completely inactivated.Regeneration was found to involve a lag period of approximately 20 hr, a rapid rate period of l‐2 days, a point of maximum regeneration at 2–10 days, and finally a decrease in activity after inactivation.The thermal destruction time (z value) of 49.8°F indicated that in high‐temperature short‐time processes the criterion for sufficiency might necessarily be based on the time required to inactivate peroxidase rather than on the time required to sterilize the product.

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