Effect of moderate electric field on peroxidase activity, phenolic compounds and color during ohmic heating of sugarcane juice

Abstract

The influence of moderate electric field was evaluated during thermal treatment of sugarcane juice. Conventional and ohmic heating (OH) experiments at temperatures of 60 and 80°C were conducted to investigate the effect of frequency (0–10⁵ Hz), waveform (sine, square, and triangle) and voltage gradient (0–16.7 V/cm) on inactivation of peroxidase (POD), phenolic compounds stability and color changes. Enzyme activity was significantly (p < .05) affected by OH; the nonthermal effects promoted POD activation at 60°C (mainly at 10 Hz) and inactivation at 80°C (mainly at 100 kHz). It was not found variation of phenolic compounds with the different operational conditions applied. Moreover, the color of the juice was modified using low frequency (possibly due to electrochemical reactions) and different waveforms. Overall, OH is suitable for POD inactivation at 80°C with the usual process parameters (sine wave and 60 Hz) or higher frequencies. PRACTICAL APPLICATIONS: Sugarcane juice is a popular energy drink, nonalcoholic, with sweet and pleasant taste. It is commercialized predominantly in the informal marketplace because its processing and marketing are limited due to its rapid deterioration. The objective of this work is to provide an alternative technology for sugarcane juice processing, ensuring safety, and lower impact on nutritional compounds, allowing its commercialization in formal markets. Ohmic heating (OH) is a faster heating technology, appropriate for pasteurization of heat‐sensitive products. The study of the effect of the process variables (temperatures, electric field frequency, waveform, and electric field strength) on enzyme inactivation, degradation of total phenolic compounds, and color stability is important to support modeling and optimization, making OH a viable technology for sugarcane juice pasteurization.