Secagem por aspersão e em camada de espuma da polpa de murta.

Abstract

Spray and foam drying of myrtle pulp. The myrtle is a fruit that stands out from the others by having significant amounts of anthocyanins. Because of its composition, the short shelf life and need to broadcast, this study aimed to dehydrate the pulp myrtle using spray drying and foam mat drying and evaluate the powdered obtained. For spray drying formulation was elaborated from whole pulp myrtle with addition of distilled water and 30% maltodextrin (DE-14) and dehydrated in the drying temperatures of 150, 170 and 190 oC. For drying the foam mat drying to select the best formulation, composed of pulp and additives myrtle (Emustab® and Super Liga Neutra®), was based on analysis of over-run parameters, density and foam stability. The selected foam was dried in an oven with forced air circulation at 50, 60, 70, 80 and 90 oC and different thicknesses (0,5, 1,0 and 1,5 cm). The myrtle pulp, selected formulations and powders were characterized for physicochemical and physical parameters. The pulp was also classified, as very acidic, with low fat percentile and relevant values of anthocyanins. The elaborated formulations presented decreased tritalable total acidity and moisture contents. The formulations of the spray drying and the foam mat drying is presented themselves as pseudoplastic fluids with Mizrahi-Berk and Herschel-Bulkley model showing the best settings, respectively. The Midili model, among the tested was that better fitted curves of drying kinetics in the foam mat drying. Increasing drying temperature the lowest values provided in powder samples of moisture content, water activity, anthocyanins, and total color difference at the two types of drying. The acidity and the insolubility of the powders showed better results for low temperatures. In a general way, there were changes in the shape of powder particles to increase drying temperatures and different types of samples. The model which best fit the experimental data of adsorption isotherms at 25 oC, the powders was Peleg. The isotherms were classified as type II and III.