Temperature Rising Indicators over 7 or 13°C for Food

Abstract

Irreversible temperature indicators were produced to keep the quality of food and raw material. Two types of indicators were developed to use at 7 and 13°C. Length of color-zone expansion against time was measured at 7 or 13°C. Their coefficients of variation were less than 10% (n=100). Color-zone expansion started from 7 or 13°C and its speed was accelerated with temperature rising. Expansion stopped under 7 or 13°C. Relationship between the color-zone expansion of indicator and the bacterial growth in food was investigated. Both the expansion of color-zone and bacterial growth increased with temperature rising. Bacterial cell number was increased even if food was placed only for a few hours at 30°C. Color of indicators developed before the bacterial growth, so that it was useful to apply the temperature indicators for keeping the quality of food and its raw material.