Dados do Trabalho

Título

THERMAL INACTIVATION OF PEROXIDASE IN MELON JUICE

Introdução

Peroxidase enzyme, one of the main deteriorative enzymes in fruit-based foods, is an indicator of efficiency in pasteurization processes due to its high thermal resistance. As it is the predominant enzyme in yellow melon (Cucumis melo var. inodorus), studying and modeling its thermal resistance is important for better control of the thermal processes of the juice, aiming to minimize quality losses of the product's sensory attributes under temperature effects. This study aimed to investigate the thermal inactivation kinetics of peroxidase in yellow melon juice at different temperatures. For this purpose, discontinuous assays were designed based on theoretical kinetic parameters of the same enzyme.

Material e Métodos

The juice was placed in 2 mL stainless steel tubes and immersed in a heating bath at 70, 75, and 80 °C. Inactivation was evaluated considering zero, first, and second-order kinetics, as well as the Activation Energy of the reaction by the Arrhenius model, Ea (kcal), and the Q10 factor. The physicochemical parameters of the juice, such as acidity (citric acid/100g), pH, and total soluble solids (TSS in °Brix) were also evaluated,

Resultados e Discussão

resulting in 9.3 °Brix, pH 6.5, and 0.51 g of citric acid/100g of juice. The first-order model showed the best fit of the data, presenting the following values of determination coefficient (R²) and inactivation rate (k) for each temperature, respectively: k70 0.039 min-1 (R² 0.846); k75 0.145 min-1 (R² 0.985); and k80 0.227 min-1 (R² 0.975). The Ea of the reaction was determined to be 42.5 kcal (R² 0.93), while the average Q10 factor was 7.3.

Conclusão

The R² values indicate a good fit to the linear first-order model, where the peroxidase enzyme is inactivated more rapidly at higher temperatures, allowing us to seek alternatives that can mitigate sensory quality losses and optimize the thermal process of yellow melon juice.