Avaliação do armazenamento a frio sobre os compostos bioativos e as características físico-químicas e microbiológicas do suco de umbu pasteurizado

Abstract

This work aimed to evaluate the effect of storage at 6 °C on the characteristics of pasteurized umbu juice. Pasteurization was carried out at 86 °C for 25 s in a scraped surface heat exchanger and storage at 6 °C for 90 days. The pasteurized umbu juice conformed to the standards established by Brazilian legislation, presenting 〈3 MPN.g-1 for coliforms at 45 °C and absence of Salmonella sp. Under these processing conditions, pasteurization was also efficient in reducing the mesophilic aerobic bacteria. The phenolic compounds content, and specifically that of rutin, and the antioxidant activity of the juice were not affected (p<0.05) by the heat treatment. Although not visually perceptible, the colour parameters of the umbu juice were significantly affected by storage (p<0.05). Although small, there was also significant variation (p<0.05) in the phenolic compounds and carotenoid contents. On the other hand, the umbu juice remained microbiologically stable during storage, showing that it is possible to preserve it for a period of 90 days without the use of preservatives when submitted to pasteurization and kept under refrigeration.