Development and application of a new time-temperature integrator for the measurement of P-values in mild pasteurisation processes

A new time-temperature integrator (TTI) for the measurement of mild pasteurisation treatments is described. The objective was to measure thermal processes of the order of a few minutes at 70 degrees C. Food products that receive these treatments are intended for sale either under refrigerated conditions with < 10 days storage, or are naturally high in acid that allows ambient storage for many months. The new TTI, referred to as BAA70, consisted of 0.5 mg/mL alpha-amylase from Bacillus amyloliquefaciens in 10 mM acetate buffer. Decimal reduction time (D(70)-value) of 8.4 min and z-value of 8.9 C degrees were calculated for BAA70 in a water bath. Maximum P-values measured with BAA70 were up to 25.2 min at 70 degrees C. Industrial evaluation for surface pasteurisation in hot-filled mini jam jars and for continuous oven cooking of quiches demonstrated the applicability of the BAA70 TTI. P-Values in both these operations could not be measured using conventional temperature sensors and so the TTIs provided invaluable data on pasteurisation achieved. (c) 2008 The Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.