Optimization of thermosonication processing of pineapple juice to improve the quality attributes during storage

The microbial and functional quality attributes of fresh pineapple juice were studied under conventional and ultrasound pasteurizations. Fresh pineapple juice was subjected to thermosonication (TS) treatments with processing variables of temperature (25-65 degrees C), time (2-10 min) and amplitude (30-70%). Response variables: total phenolic content (TPC), bromelain activity and microbial inactivation were optimized using response surface methodology. The optimized TS treatment conditions for juice were 62.33 degrees C, 2 min and 35.32% amplitude, which corresponded to bromelain activity of 63.24 U/100 mL of juice, TPC of 177.3 mu g GAE/100 mL, total plate count 2.74 log CFU/mL and yeast & mold count 2.301 log CFU/mL. Shelf-life of TS treated, pasteurized and control pineapple juices was evaluated for 28 days at 4 degrees C. TPC, ascorbic acid and protein contents of TS treated juice were significantly higher than pasteurized juice after 28 days of storage. Due to high efficiency in the retention of nutritional and quality parameters, TS processing can be opted by juice processing industries as an alternative to convention pasteurization.