Design of a batch Ohmic heater and evaluating the influence of different treatment conditions on quality attributes of kinnow (Citrus nobilis × Citrus deliciosa) juice

Abstract

A batch Ohmic heater (5 L) with a modified electrode arrangement was designed for quick and uniform heating of kinnow juice. A T-shaped arrangement and micro silver coating over stainless steel electrodes provided temperature variation of 0–2 °C across the system and a system performance coefficient of 0.96. The come-up time for 60–80 °C was 1.3–3 min at 180 V. Pectin methylesterase, the most resistant enzyme, was inactivated completely at (120 V/80 °C/1 min), (150 V/80 °C/30 s), (180 V/70 °C/10 s). No aerobic mesophiles, yeasts, and moulds were detected in these samples. Ohmic heating at 180 V did not influence the colour of the juice significantly; however, some samples showed a little elevation (by 0.2) in the pH. The reduction in vitamin C, antioxidants, and total phenols was 6–12% at 150 V/80 °C/30 s. The fuzzy analysis shows that the Ohmic pasteurized juice had the highest similarity score. Industrial relevancesA batch assembly (5 L capacity) of the Ohmic heater has been fabricated to make a shelf-stable kinnow juice. The produced juice is microbially safe, enzymatically stable, and retains maximum bioactive compared to conventional thermal treatment. Thus, Ohmic heated juice can fulfill the stakeholders' demand for microbial safety, enzymatic stability, and nutritional superiority. Industry can scale up the design of batch Ohmic heater for efficient and faster pasteurization of citrus juice like kinnow juice.