Influence of thermosonication and pasteurization on the quality attributes of kutkura (Meyna spinosa) juice

Abstract

The impact of pasteurization (90 ± 2°C for 60 s) and thermosonication (33 kHz & 44 kHz at 30, 40, 50°C for 30, 45 and 60 min) on the quality of kutkura (Meyna spinosa) juice were examined and the finding of the work were compared with fresh kutkura juice. The quality attributes including, physicochemical (pH, titratable acidity (TA), total soluble solids (TSS), cloud index (CI), browning index (BI)), functional (total phenolic content (TPC), total flavonoid content (TFC), and anti-oxidant activity (AOA)) and microbial properties of processed and fresh juices were analysed. Thermosonicated kutkura juice samples showed minimal changes in the physiochemical properties in comparison to fresh and thermally treated juices. Enhancements in TPC (476.32-579.87 mg gallic acid equivalents (GAE)/mL), TFC (71.42-99.89 mg quercetin equivalents (QE)/mL), and AOA (65.10 – 83.18%) of thermosonicated kutkura juice were observed as compared to pasteurized (TPC- 399.83 mg GAE/mL, TFC- 51.02 mg QE/mL, AOA- 49.91%) and fresh (TPC- 421.21 mg GAE/mL, TFC- 61.38 mg QE/mL, AOA- 56.40%) kutkura juices. Additionally, retention of ascorbic acid was also found to be higher in thermosonicated juices (27.10 – 36.42 mg/100 mL) as compared to pasteurized juices (26.14 mg/100 mL) and lower than the fresh kutkura juice (37.21 mg/100 mL). Thermally processed juices showed complete inactivation of microbial counts and thermosonication has decreased the TVC (3.45-4.17 log CFU/mL) and YMC (3.59-4.49 log CFU/mL) when related to the microbial counts of fresh juices (TVC- 4.86 log CFU/mL & YMC- 4.95 log CFU/mL). According to the findings, thermosonication could be a viable alternative to thermal pasteurisation for preserving kutkura juice with no/minimal quality loss and improved functional attributes.