Activity of oxidative enzymes involved in the browning of minimally processed sweet cassava (Manihot esculenta Crantz)

Recent studies report that the shaped minimally processed sweet cassava 'Rubiene shape', when submitted to turning, presents extended useful life compared to the not turned one, i.e., the ‘Minitolete shape’. This behavior may be related to a greater participation of enzymes involved in protection against oxidative damage. The objective of this research was to evaluate the effect of the minimally processed sweet cassava shape on postharvest physiological deterioration with emphasis on the activity of oxidative enzymes involved in the darkening of tissues. Sweet cassava roots, cv. Mossoro, were produced in the experimental field of the Unidade Academica de Serra Talhada, in Serra Talhada - PE, Brazil. After 14 months, they were harvested and minimally processed in Minitolete and Rubiene shapes. The product consisting of a package containing approximately 200 g was stored at 5 ± 2 °C and 90 ± 5% RH for 11 days. The experimental design was completely randomized using a 2x6 factorial design, referring to shapes and refrigerated storage times with 3 repetitions. Visual analysis of the processed product, total soluble phenols, polyphenol oxidase enzyme activity, peroxidase, superoxide dismutase, catalases and ascorbate peroxidases were evaluated. The reserve parenchyma cells, remaining on the Rubiene shape were less responsive to postharvest physiological deterioration, in contrast to the sensitivity observed in surface tissues of the 'Minitolete shape'. This indicates that changes in the phenolic and oxidative metabolism of sweet cassava roots are tissue-dependent. The Rubiene shape maintained its quality during the 11 days of storage at 5 ± 2 °C, 4 days more if compared to the 'Minitolete shape'.