Zou_2025_J.Food.Sci_90_e70696

This study investigated the inhibitory effect of ohmic heating (OH) on pectin methylesterase (PME) and polygalacturonase (PG) and its effects on tomato juice quality and microbial diversity. Combining the effects of voltage gradient and electric field frequency on the activities of PME and PG, the voltage gradient of 10 V/cm and the frequency of 150 Hz had the best inactivation effect. At 65 degreesC and 150 Hz, the activities of PME and PG can be reduced by more than 10% and 7%, respectively. With storage time, the color of tomato juice gradually deteriorated. The color in OH treatment group with high temperature was worse than low temperature. The contents of lycopene, total phenol, vitamin C, and soluble pectin decreased with storage time. Compared to control group, 65 degreesC OH treatment can increase vitamin C by 2 mg at 25 days. The total number of colonies in 65 degreesC OH treatment exceeded the standard at 18 days of storage. The total number of colonies decreased by 65% compared with the control group. In terms of microbial diversity treated with OH (10 V/cm, 150 Hz, 65 degreesC), Delftia and Paleobacterium were the dominate genus. Panobacterium gradually became the dominant group due to interspecific competition, so the microbial diversity decreased at the end of storage. These results systemically provided a theoretical basis for the subsequent targeted industrial application of reducing spoilage microorganisms using OH technology.