Secagem por aspersão de polpa de atemoia.

Abstract

The atemoya is a fruit that is increasingly attracting the attention of consumers due to their organoleptic characteristics, and the producer because of its high commercial value, but the fruit has a shelf-life short. The objective of this work was to study the drying of atemoya pulp in spray drying. For this, were performed preliminary tests with formulations prepared with 50% atemoya pulp and 50% water, added of different concentrations of maltodextrin (25, 30 and 35%) and dextroses equivalent (10, 14:20) under conditions of drying: inlet temperature - 170 °C and feed flow rate - 0.3 Lh"1 . Subsequently, the chosen formulation was subjected to a factorial experimental design with two input variables: air temperature drying (160, 170 and 180 °C) and flow rate (0.3, 0.5 and 0.7 L h"1), as purpose if define best drying conditions. Both for the selection of the formulation of the conditions of drying parameters evaluated were moisture, water activity, color, vitamin C and yield. The powder formulation produced with pre-set the best drying conditions was characterized chemical, physical, physico-chemical properties and morphology. Were determined the moisture adsorption isotherms at 20, 30 and 40 °C, times of half-life of kinect of ascorbic acid degradation, at 20, 30 and 40 °C and relative humidity of 55% and analyzed the influence of temperature through the Arrhenius equation. From tests preliminary selected- if the formulation elaborated with 25% maltodextrin DE-10, and through design experimental factorial defined itself as being the best drying conditions by sprinkling the inlet temperature of 180 °C and feeding flow of 0.3 L h . The powder samples (collected in the drying chamber and cyclone) had a moisture content of 1.37 ± 0.04 and 0.49 ± 0.01 %w.b., respectively. The powder collected in the drying chamber is more soluble and has a larger amount of voids than powder the cyclone. The particles of the two samples showed no spherical shape, these formed aggregates gooey. The Peleg model generally provided the best fit to the experimental data of moisture adsorption isotherms, with R2 > 0.99 and P<9% and R2 > 0.99 and P <5% for the dust collecting chamber drying and cyclone, respectively. The adsorption isotherms of the dust collected in the drying chamber were classified as Type III, and in general the cyclone powder samples were classified as Type I I. The highest ascorbic acid degradations occurred with higher temperatures. The reduction rales were approximately 0.73 mg lOOg"1 dia"1 ; 1.01 mg lOOg"1 dia"1 and 1.24 mg lOOg"1 dia 1 , at 20, 30 and 40 °C, respectively. For the first-order reaction was obtained R 2 >0.93. The half-life decreased with increasing temperature and the activation energy of the powder collected in the drying chamber was 31.16 kJ.mol"1 .