Secagem em camada de espuma da polpa de atemoia e armazenamento do pó.

Abstract

This work was developed in order to obtain a powder product from the whole pulp of atemoya through the foam mat drying, and evaluate the dried product characteristics as well as its stability. Foams were prepared from the whole pulp with addition of 1.0; 1.5 and 2.0% of Emustab and Super Liga Neutra with different beat times (10, 15 and 20 minutes) according to the factorial design 23 with three central points; the selection of the foam was made using the results of the density parameters of the foams according to the beating time, volume expansion (over run) the kinetic stability of the foam. The foam was selected as the best dehydrated in an oven with forced air circulation at different temperatures (55.85; 60; 70; 80 and 84.15 °C) and the foam layer thicknesses (0.29; 0.5; 1.0; 1.5 and 1.71) as the central composite factorial design 22 + 4 axial points and three central points. The drying rate curves were plotted relative to the moisture ratio and applied the models semi-theoretical Henderson & Pabis, Page and Midilli. The whole pulp, foams and powders were characterized for physical, chemical and physico-chemical parameters. For choosing the best powder were considered the results of parameters moisture content, total solids, ascorbic acid, brightness, redness and insolubility. With the selected powder was determined ascorbic acid degradation kinetics in controlled conditions of humidity (83%) and temperature (20, 30 and 40 °C) for a period of 15 days; evaluated the stability of the powder during the accelerated storage with a relative humidity of 55 and 83% and temperatures of 20; 30 and 40 °C for 60 days, the study was conducted of moisture adsorption isotherms at temperatures of 20; 30 and 40 °C. The pulp was considered integral atemoya little acidic. According to the process of forming the foams, it was found that the foam was the best performing atemoya composed of pulp, 2% Emustab and 2% Super Liga Neutra, with a 20 min beating time. For the drying kinetics Midilli the model was what presented the best fit for all conditions. According to the process of forming the powder atemoya found that the best performing powder was dried at 80 °C and 0.5 cm thickness of the layer. The rate of degradation of ascorbic acid was increased to 40 °C and the temperature studied the degradation of ascorbic acid follows zero order kinetics models. During storage of the powder atemoya laminated packaging, it was found that there was an increase with time of moisture content, water activity and solubility and reduced ascorbic acid and brightness. The moisture adsorption isotherm of the powder atemoya was classified as Type II for all temperatures studied (20, 30 and 40 °C) while models GAB, Oswin and Peleg can be used to estimate the isotherms.