Atividade de enzimas oxidativas envolvidas com o escurecimento em mandioca de mesa minimamente processada

Abstract

Recent studies report that the format of minimally processed sweet cassava Rubiene, subjected to turning, has longer life compared to the non-turning mini-oarlocks. This behavior may be related to greater participation of enzymes involved in protection against oxidative damage occurred during storage. Thus, studying the relationships of phenolic and oxidative metabolism in different formats of minimally processed sweet cassava can bring additional information to what is known about the darkening of their tissues when cut. The objective of this study was: to evaluate the effect of the shape of minimally processed sweet cassava on post-harvest physiological deterioration with emphasis on the activity of oxidative enzymes involved with the darkening of tissues aiming at better understanding of the phenolic and oxidative metabolism. Roots of sweet cassava cv. Mossoró were produced between August 2011 and July 2012 in the experimental field of the Academic Unit of Serra Talhada/Universidade Federal Rural de Pernambuco, Serra Talhada - PE. At 14 months of age, were collected and minimally processed in Mini-oarlocks and Rubiene shapes. The product with a package containing about 200 g was maintained at 5 ± 2 °C and 90 ± 5% relative humidity for 11 days. The experimental design was completely randomized in a 2x6 factorial design, referring to shapes (Mini-oarlock and Rubiene) and refrigerated storage times (0, 3, 5, 7, 9 and 11 days), respectively, with 3 replications. Visual analysis of the processed product, total soluble phenols, polyphenol oxidase enzyme activity, peroxidase, superoxide dismutases, catalases and ascorbate peroxidases were evaluated. The results indicated that changes in phenolic and oxidative metabolism in roots of sweet cassava are tissuedependent, because the storage parenchymal cells, remaining in the Rubiene shape, were less responsive to post-harvest physiological deterioration, in contrast to the sensitivity observed in the superficial tissues of 'Mini-oarlock'. Thus, the intensity of the injury was not related to darkening, or the severe oxidative damage. Thus, the shape Rubiene remained quality during the 11 days of storage at 5 ± 2 °C, 4 days more compared to the 'Mini-oarlock'.