Effect of ohmic heating on physicochemical properties and the key enzymes of water chestnut juice

To explore processing methods that can inhibit enzymatic browning and have less negative effects on the quality of water chestnut juices, it was heated using ohmic heating at different electric field strengths (EFS) and frequencies. There were no significant differences between conventional and ohmic heating for the levels of total sugar, total acid, and soluble solids. The color difference of them was within an acceptable range. The retention rate of vitamin C after ohmic heating (10.6-11.4%) was significantly lower than conventional heating (14.7%) (p<0.05). Ohmic heating can activate peroxidase (POD) activity initially and then deactivate it rapidly thereafter. The higher the EFS, greater could be the enzyme activation. The electric frequency had no significant effect on POD activity. The polyphenol oxidase (PPO) activity declined rapidly with the treatment of ohmic heating and the critical deactivation temperature was 35 degrees C. Practical applicationsIt may be a suitable model to study ohmic heating while being of practical value to those wanting to safely process water chestnut juice. Using ohmic heating can deactivate POD and PPO at lower temperatures and in a shorter time without major negative effect on juice quality, so it may be beneficial for water chestnut juice processing. Besides, ohmic heating is also a good approach to save energy and electricity.