Efeito do congelamento e da estocagem na atividade enzimática da polifenoloxidase (PFO) e peroxidase (POD) e na composição físico-química de polpa congelada de cupuaçu (theobroma grandiflorum schum)

Abstract

Cupuaçu (Theobroma grandiflorum Schum.) is one of the most popular fruit of Amazon. The pulp is commercialized in two forms: pasteurized or non pasteurized. During processing, the pulp becomes dark due to reactions catalyzed by oxidative enzymes: such as peroxidase and polyphenol oxidase. These enzymes are naturaly present in the fruit and causes alteration in its color, and also, in degradation of fruit nutrients, especially during the storage. Generally, freezing and pasteurization are used to minimize the effect caused by the oxidation reactions and to eliminate part of the microorganisms present in the fruit. The objective of this study was to evaluate the enzymatic alterations in three lots of frozen cupuaçu pulp, received from different regions, on pasteurized and non pasteurized forms and stored in between -25ºC and - 30ºC for a 12 months period. The physico-chemical analyses were carried according to Norms of the Instituto Adolfo Lutz (2005) and the analyses of polifenoloxidase and peroxidase, according to Oktay et al. (1995) and Khan and Robinson (1994), respectively. After one year of storage, it was observed that the source of each lot, the time of storage and the pasteurization processing show significant influences (1%, p<0,05) in total solid level, ascorbic acid content, titratable acidity and peroxidase activity. The source of each lot, the pasteurization processing, times of storage and the interaction between lot source and pasteurization processing showed significative differences (1%, p<0,05) on the sugars content. The polyphenol oxidases in the pasteurized and non pasteurized pulps, from the three lots, presented variations during twelve months of storage under freezing.