Secagem de polpa do fruto do mandacaru.

Abstract

This work was carried out in order to dehydrate the mandacaru pulp and to evaluate the obtained powder product. Initially, several formulations were tested for the production of stable foam composed by mandacaru pulp as well as several types and concentrations of addictive. Based on the analysis of the volumetric expansion, foam density and stability, the composed of mandacaru pulp with albumin (2%) and Super Liga Neutra (2%), with a 5-minute whipping time, was selected as the best formulation. The mandacaru pulp and the selected foam were characterized according to their physiochemical and physical parameters. The selected foam was dried in oven with air circulation at 70, 80 and 90 °C, with three different foam layer thickness (0.5; 1.0 and 1.5 cm). The drying curves followed Page's, Henderson & Pabis's and Cavalcanti Mata's models. The sample powder was analyzed physical-chemically and physically, in order to evaluate the influence of the drying temperature and foam layer thickness parameters. The moisture adsorption isotherms of the sample powder were determined at 20 °C. The GAB, Oswin and Peleg models were the ones that best fit the isotherms. It was verified that the whole mandacaru pulp is acid, rich in pectin and a pseudoplastic non-newtonian fluid. The Mizrahi-Berk model was the one that best fit the rheograms. The selected formulation presented a foam density of 0.1566 g/cm3 and the addictive present in the foam influenced the characteristics of the whole pulp. The foam drying was influenced by the foam thickness and temperature of drying. The fastest process occurred in the lowest thickness in a higher temperature. The kinetics drying curves fit best with Cavalcanti Mata's model. The model that fit best with the mandacaru powder moisture adsorption isotherms dried at 70 and 80 °C was the Peleg and, for the samples dried at 90 °C, the GAB model fit best. The moisture adsorption isotherms of the powder samples dried at 70, 80 and 90 °C were classified as Type II, except for the samples dried with a 0.5 cm foam-layer thickness dried at 70 and 80 °C, which were classified as Type III.