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

Abstract

AbstractThis 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 D70°C (OH: 3.61 min, CTP 7.32 min), except D80°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.Practical ApplicationsInactivating enzymes that alter quality aspects of food products, such as polyphenol oxidase (PPO), is an important objective of a food processing technology. PPO is an enzyme commonly found in fruits and vegetables that catalyzes browning reactions. Ohmic heating (OH) is a technology known for its potential for processing highly viscous products. This study corroborates the potential of OH for processing highly viscous fluids over conventional thermal processing (CTP), having a great potential to be an alternative technique to food processing. In addition, it gave more evidence of the nonthermal effects due to the electrical current during the ohmic processing.