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 °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 α-amylase from Bacillus amyloliquefaciens in 10 mM acetate buffer. Decimal reduction time (D70-value) of 8.4 min and z-value of 8.9 C° were calculated for BAA70 in a water bath. Maximum P-values measured with BAA70 were up to 25.2 min at 70 °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.