The effect of different time-temperature pasteurization conditions on shelf-life of low-fat cream

The objective of the present study was to evaluate the possibility of extending the shelf life of low-fat cream (25%) through finding a novel time-temperature condition for its pasteurization. The low-fat cream samples were thermally pasteurized at different temperatures (80, 85 and 90 °C) for different times (15, 20 and 25 min) and were evaluated for physicochemical (pH, acidity, viscosity) and microbial (total bacterial count, psychotropic bacterial count) properties at different storage times (days 1, 4, 7, 10, 13, 16 and 19) in comparison with control sample (pasteurized at 75 °C for 30 min). The results indicated that microbial counts increased during the shelf life, accompanying with decreased pH and increased acidity of the creams. The samples treated at more severe thermal pasteurization conditions had better microbial quality resulting in less variation in their pH and acidity values during storage. The results showed that treating upon more sever time-temperature conditions and prolonged storage both led to higher viscosity for cream samples. All freshly-prepared samples showed shear-thinning behavior which was intensified at more sever time-temperature pasteurization conditions. Among different treatments, the sample pasteurized at 90 °C for 25 min had the longest storage duration.