Effect of microwave-assisted processing on polyphenol oxidase and peroxidase inactivation kinetics of açai-berry (Euterpe oleracea) pulp

• Published in: Food chemistry Vol. 341; no. Pt 2; p. 128287
• Main Authors: Costa, Henrique Coutinho de Barcelos, Siguemoto, Érica Sayuri, Cavalcante, Tiago Augusto Bulhões Bezerra, de Oliveira Silva, Danylo, Vieira, Luiz Gustavo Martins, Gut, Jorge Andrey Wilhelms
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 30.03.2021
• Subjects: Catechol Oxidase - metabolism; Dielectric properties; Enzyme; Euterpe - metabolism; Hot Temperature; Juice; Kinetics; Microwave processing; Microwaves; Pasteurization; Peroxidase - metabolism; Thermal processing; Juice; Thermal processing; Enzyme; Dielectric properties; Pasteurization; Microwave processing
• ISSN: 0308-8146; 1873-7072
• DOI: 10.1016/j.foodchem.2020.128287

•Dielectric properties evaluated at 915 and 2,450 MHz up to 120 °C.•Penetration depth decreases with temperature at 915 MHz but constant at 2450 MHz.•PPO and POD inactivation described with first order two-component model.•POD was more thermally resistant than PPO.•The inactivation rate depended on the heating technology. Microwave heating has been considered a promising technology for continuous flow thermal processing of fluid foods due to better retention of quality. Considering the importance of açai-berry pulp and its perishability, the inactivation kinetics of peroxidase (POD) and polyphenol oxidase (PPO) were investigated under conventional and microwave heating. First-order two-component model was well fitted to the data, indicating the presence of at least two fractions with different resistances. POD was more thermally resistant (90% inactivation for 40 s at 89 °C) and could be considered as a processing target. Inactivation curves dependency on heating technology suggests specific effects of microwaves on the protein structure. Additionally, the dielectric properties of açai-berry pulp were evaluated at 915 and 2,450 MHz for temperatures up to 120 °C. Power penetration depth dropped with temperature at 915 MHz (from 29 to 11 mm), but was less affected at 2,450 MHz (between 8 and 11 mm).