Sensorial, biochemical and microbiological evaluations of guacamole, an avocado based product, under cold storage and added with ascorbic acid

Abstract

The elaboration of avocado products for commercialization keeping their characteristics of fresh product has been limited. The cut avocado darkens quickly and their sensorial characteristics are modified with the storage. In the present research, the sensorial parameters, microbiological stability, and peroxidase and polyphenoloxidase activity were evaluated in guacamole added with ascorbic acid and conserved under low temperature, by using avocado variety Hass. Products were conditioned in polyethylene+nylon packages with and without vacuum application; then, they were subjected to the slow and fast freezing (-18ºC) and stored in freezer (-18ºC). Evaluations were performed at the moment of elaboration of the product (t0) and at 3, 7 and 30 days post-storage. At t30, samples were kept under refrigeration (4 ±1^oC) and evaluated at 3, 5 and 7 days. After the 30 days of storage, –18 ºC under freezing, followed by thawing and keeping at 4±1ºC for 7 days, the notes for the sensorial parameters decreased. The peroxidase activity was totally inhibited in the elaborated product and the polifenol oxidase activity considerably decreased in the guacamole (20.07 mM catechol/g fresh matter) relative to those in the fruit (58.31 mM catechol/g fresh matter), however with no significant variation during storage (at -18ºC). The samples were microbiologically stable under the conditions of the present study. The addition of ascorbic acid contributed to the conservation of the frozen avocado product by decreasing the enzymatic activity. However, the sensorial parameters are prejudiced under thawing and storage at 4 ±1^oC.