Comparison of high- and low- frequency thermosonication and carvacrol treatments of carrot juice: microbial inactivation and quality retention.

The current study evaluated the comparative effects of carvacrol (CRV) with low- (24 kHz, TS) or high- (861 kHz, HTS) frequency thermosonication on microbial inactivation and quality parameters of carrot juice. The combinations of mild heat, ultrasound and carvacrol proved to be synergistic against aerobic bacteria (AB), yeast and molds (Y&M) and were effective for improving quality characteristics of juice. The optimal condition was CRV+TS (13.3 W/mL, 2.6 µM, 52 °C, 40 min) and CRV+HTS (13.3 W/mL, 2.6 µM, 52 °C, 40 min), under these treatments, AB and Y&M were inactivated by 2.74±0.18 and 2.28±0.21 log, 4.71±0.00 and 2.40±0.09 log, respectively. Compared to CRV+TS at 52 °C, CRV+HTS could extend the shelf life of juice by 25 days at 6 °C, with lower microbial amount and higher sedimentation stability. Overall, this study demonstrated the potentials of the combined approaches based on thermosonication and carvacrol to produce juice with the desired...