Influence of Thermo-sonication and Ascorbic Acid Treatment on Microbial Inactivation and Shelf-Life Extension of Soft Persimmon (Diospyros kaki T.) Juice

This study applied hurdle technology to achieve effective microbial inactivation, and concurrently improve the qualities of soft persimmon juice during storage. Hurdle technology applied was based on moderate temperature, ultrasonication, and pH adjustment (using ascorbic acid) as preservative factors. The inactivation effect of preservative factors and their varying combinations at different levels on Escherichia coli and Listeria monocytogenes was investigated via a stepwise approach to determine suitable inactivation conditions. The hurdle treatment for soft persimmon juice was determined based on the results of microbial inactivation and sensory test as the addition of 1% ascorbic acid combined with thermo-sonication at 50 °C for 30 min (AAUSHT). The effect of individual and hurdle treatment on juice storage quality was examined for 21 days at 4 °C. AAUSHT effectively inhibited both bacteria and fungi growth (< 0.5 log CFU/mL) in juice samples all through the storage period, as compared with other treatments (> 4 log CFU/mL). Furthermore, AAUSHT effectively reduced non-enzymatic browning, color change, and maintained apparent viscosity of juice.