Inactivation Kinetics of Pectin Methylesterase, Polyphenol Oxidase, and Peroxidase in Cloudy Apple Juice under Microwave and Conventional Heating to Evaluate Non-Thermal Microwave Effects

Author(s)

Siguemoto, Erica Sayuri ^[1] ; Pereira, Leticia Jyo ^[1] ; Wilhelms Gut, Jorge Andrey ^{[1, 2]}

Affiliation

^[1] Univ Sao Paulo, Dept Chem Engn, Escola Politecn, Ave Prof Luciano Gualberto, Trav 3, 380, BR-05508010 Sao Paulo, SP - Brazil

^[2] Univ Sao Paulo, FoRC Food Res Ctr, Rua Lago 250, BR-05508080 Sao Paulo, SP - Brazil

• Document type: Journal article
• Source: Food and Bioprocess Technology; v. 11, n. 7, p. 1359-1369, JUL 2018.
• Web of Science Citations: 7

Abstract

Continuous-flow microwave pasteurization provides important advantages over conventional heat exchangers such as fast volumetric heating, lower tube surface temperature, and possible non-thermal effects that enhance enzymatic and bacterial inactivation. Conventional and microwave-assisted inactivation of pectin methylesterase (PME), polyphenol oxidase (PPO), and peroxidase (POD) in cloudy apple juice were investigated to evaluate non-thermal effects. Experiments were conducted to provide uniform heating with accurate temperature acquisition and similar temperature profiles for conventional and microwave treatments. A two-fraction first-order kinetic model was successfully fitted to the data in a procedure that took into account the whole time-temperature profile instead of assuming isothermal conditions. Predicted inactivation curves for pasteurization at 70 and 80 A degrees C of the cloudy apple juice showed that PME has the highest thermal resistance (residual activity of 30% after 250 s at 80 A degrees C) and that there was no evidence of non-thermal microwave effects on the inactivation of these enzymes. (AU)

• FAPESP's process: 14/06026-4 - Study of continuous-flow microwave thermal processing of cloudy apple juice
• Grantee: Érica Sayuri Siguemoto
• Support Opportunities: Scholarships in Brazil - Doctorate
• FAPESP's process: 13/07914-8 - FoRC - Food Research Center
• Grantee: Bernadette Dora Gombossy de Melo Franco
• Support Opportunities: Research Grants - Research, Innovation and Dissemination Centers - RIDC
• FAPESP's process: 14/17534-0 - Evaluation of the effects of focused microwave processing on liquid foods
• Grantee: Jorge Andrey Wilhelms Gut
• Support Opportunities: Regular Research Grants