Polyphenol oxidase inactivation in viscous fluids by ohmic heating and conventional thermal processing

Abstract

This study investigated polyphenol oxidase (PPO) inactivation in a viscous solution of carboxymethyl cellulose (CMC) by ohmic processing (OH) and conventional thermal processing (CTP) at several temperatures and to assess the impact of CMC consistency on PPO inactivation. OH affects the PPO activity in temperatures higher than 50 C (reduction to 20% at 50 C, 12 min and complete inactivation after 2 min at 80 C), whereas CTP caused a significant reduction in PPO activity only above 60 C (reduction to 90% at 60 C, 8 min and complete inactivation after 2 min at 80 C). The rate of PPO inactivation by ohmic heating was higher than by CTP under all conditions tested, represented by a reduction of D 70 C (OH: 3.61 min, CTP 7.32 min), except D 80 C was 0.5 for both techniques. The Z-value was higher for OH (14.68 C) than for CTP (8.60 C).Consistency did not have a major impact on inactivation rate.

Anthocyanin Recovery from Grape by-Products by Combining Ohmic Heating with Food-Grade Solvents: Phenolic Composition, Antioxidant, and Antimicrobial Properties

“…Furthermore, some studies also indicate that the heating process and the electric field could potentiate synergies affecting enzymatic activities, such as the polyphenol oxidase activity, which indirectly degrades the monomeric anthocyanins during enzymatic browning [36,37]. Eventually, the electric effects can activate or inactivate enzymes, since there are studies that report effects on the enzymes [38][39][40][41]. However, further studies would be needed to confirm whether the same is true in this case.…”

Ohmic Heating Technology for Food Applications, From Ohmic Systems to Moderate Electric Fields and Pulsed Electric Fields

“…The application of food preservation treatments also involves the inactivation of enzymes. As described for microbial inactivation, the thermal effect would be the major cause of enzyme inactivation, but an electrical (non-thermal) inactivation has also been reported in the literature [102][103][104]. In this case, this non-thermal effect would be related to changes in enzyme structure leading to increased structural dynamics and reduced cohesion of the protein [105].…”