Caracterização físico-química de suco de acerola (malpighia emarginata dc) em pó obtido através das técnicas de spray dryer e refractance window

Abstract

Acerola is a fruit rich in vitamin C of fragile structure and easily deteriorat, so the need for processing techniques that increase its shelf life. Refractance window and spray dryer are dryers used for food conservation by reducing moisture. The present work had the objective of obtaining the acerola powder by the refractance window and spray dryer methods in different processing conditions, analyzing the quality of the final processed product, by comparing the physicochemical properties of the powder between both methods and the concentrate juice, as well as the evaluation of drying kinetics and vapor adsorption isotherms through the application of mathematical models. A drying apparatus for the refractance window was developed with some modifications and adaptations. The concentrate juice of acerola was subjected to the drying processes in the refractance window at temperatures: 85, 90 and 95 °C, with concentrations of maltodextrins: 20, 25 and 30% (w/w) and juice mass of 150, 200 e 250 g; and in the spray dryer, with inlet temperature: 140,150 and 160 °C, with the same of maltodextrin concentrations of refractance window and blower flow of: 2.5; 3.0 and 3.5 m3 .min-1 . The physico-chemical analyzes (pH, total soluble solids and ascorbic acid) of the acerola concentrate juice compared to powder processed for both drying methods differed statistically (p≤0.05) by the tukey test, with the exception of the pH parameter for spray dryer. The spray dryer showed better properties of pH, moisture, and water activity and the refractance window showed better properties of bulk density, tapped, particle, angle of repose, solubility and yield. The diffusional model applied to the drying kinetics of the refractance window and the parallel exponential kinetic model (PEK) applied to the vapor adsorption isotherms for both methods presented a good fit to the experimental data. The process conditions had no influence on the mean particle diameter in the particle size analyzes. The analysis of the morphology of the powder processed by the refractance window presented particles with irregular shapes and for the spray dryer with spherical shape.