Effect of heat treatment on the storage stability of low calorie milk drinks.

Abstract

The study was undertaken to study the effect of heat treatment on the storage stability of cardamom flavoured low calorie milk drinks (CFDs). The drinks prepared by replacing sugar with sucralose and adding inulin in milk of 0.5% fat and 8.5% milk solid-not-fat were subjected to pasteurization and sterilization and stored at refrigeration and room temperature, respectively. The stored samples were evaluated for changes in physico-chemical and sensory attributes at regular intervals. In pasteurized drinks, the total solids (TS) and pH declined while the total soluble solids (TSS), titratable acidity and viscosity increased significantly (p < 0.01) with storage. A significant reduction in the flavour and body and mouthfeel scores was observed. Standard plate count (SPC) increased in both control and low calorie drinks with storage period. In sterilized CFDs, TS and TSS were not affected appreciably whereas titratable acidity increased and viscosity decreased significantly (p < 0.01) with storage. Though the sensory scores also declined with storage, the drinks obtained high acceptability scores even after 150days of storage at room temperature. However, the changes in colour components (L, a and b values) indicated increased browning in the drinks with storage time. SPC was not detected until 120days in control and 135days in low calorie drink. Yeast and molds were not evident until 135days in control and 150days in low calorie drink. The shelf life was found to be 10 and 150days of pasteurized and sterilized CFDs at refrigeration and room temperature, respectively.