Avaliação das propriedades reológicas de suco de abacaxi adicionado de yacon, vitamina c e goma xantana

Abstract

The pineapple is a fruit of flavor, characteristic taste and lush appearance. Pineapple juice is a clear or cloudy liquid extracted through rheological processes, keeping its sensory characteristics. Yacon is a tuber with andine origin, possessing fructans as reserve carbohydrates, acting as soluble fibers, it presents a sweetish taste, being used to develop new products as replacements for sugar. Vegetable origin products have a greater degrading rate, and that flaw can be corrected through the addiction of vitamin C, heightening the product lifespan. The xanthan gum acts in the juice’s viscosity, improving the rheological properties. This work aimed to study the rheological behavior of pineapple juice added yacon, vitamin C and xanthan gum in the temperature range of 10, 20, 30, 40, 50 and 60ºC and analyze the rheological parameters from Ostwald-de-Waele (Potency Law), Herschel-Buckley, Casson and Bingham mathematical models. For the juice production, it was realized the extraction of yacon pulp, following the cleaning process, bleaching, pasteurization (90ºC/1min) and storage. The rheological analyzes were realized using the spindle SC4-31 with a deformation tax rate varying from 0 to 85 s-1. The temperature effect on the juice’s apparent viscosity was described by the Arrhenius equation, the activation energy value found was 8,839 kJ.mol-1, which indicates that the temperature have a minor influence on the studied juice. The juice presented a Non-Newtonian behavior and a pseudo-plastic character for all the studied temperatures, therefore, Ostwald-de-Waele (Potency Law) and Herschel-Buckley models were the ones that better adjusted to the rheological data.