Termoconversão do amido de mandioca (manihot esculenta crantz) na presença do ácido lático: caracterização de propriedades físico-químicas e aplicação como material encapsulante do ácido ascórbico

Abstract

Thermoconversion process consists of submitting starch with a low water content at high temperatures with an acid catalyst to obtain dextrin The purpose of this study was to modify the cassava starch by thermoconversion process and characterize it as its physical and chemical characteristics and encapsulating of ascorbic acid. For this reason, there was the modification cassavaa starch with different concentrations of lactic acid, obtaining the following tests: Sample B (2.5% lactic acid), Sample C (5.0% lactic acid) and Sample D (7 5% lactic acid). Samples B, C and D were characterized according to esterification degree by analytic method and it was obtained, in this order, level of 1.64, 2.51 and 4.57 % of lactyl. Using FTIR spectra analysis, it was identified peaks at 1750 cm-1 wavelengh, characteristic of the ester group, exclusively on Sample D. The samples modified with lactic acid showed lower amylase content as it increased the concentration of lactic acid during modification. This reduction resulted in solubility increasing of the dextrin in water at temperatures of 65 to 80°C when compared to native cassava starch. The clarity of the gels paste for sample B, C were notably superior to transmittance values found in the native cassava starch and sample D. In the apparent viscosity analysis of gels, it was observed low viscosity of dextrin n time 0 and after 24 h of storage (4°C). Dextrins obtained by modification process were applied as encapsulation agents of ascorbic acid and, for comparison, it was used maltodextrin 10 DE and Dextrin 17, both dextrins are already used in industry. By spray- drying process it was obtained microcapsules of ascorbic acid which were storage in ambient temperature (25- 30 °C) for 45 days. It was noticed that sample D showed a decrease of 6,1% in the ascorbic acid during storage time, lower waste when compared to the others. Concluded with these results, good retention efficiency and protection of ascorbic acid by dextrin modified with 7.5% lactic acid and this may be associated with the presence of hydroxyl on the side of starch that favored the interaction with the encapsulated material.