The impact of different temperatures on spore count and browning of UHT milk over a long storage period

Abstract

One of the major microbiological challenges for the ultra-high temperature (UHT) milk industry is the presence of sporeformers in milk, which can survive pasteurization and the UHT process. The present study has aimed to investigate the spore populations in UHT milk stored at 20°C and 35°C for 14 months. Samples of bulk tank milk, pasteurized milk, and UHT milk were randomly assigned to different temperatures and storage times and were analyzed to study the mesophilic populations of aerobic spores and any color changes. The results showed that aerobic sporeformers can survive the UHT process. Bacillus licheniformis group and Bacillus pumilus group were the most isolated aerobic sporeformers. The b* value increased significantly in samples stored at 35°C. These data provide information on the aerobic spore populations of bulk tank milk and UHT milk produced in different seasons and stored at different temperatures for 14 months.