Physical and chemical stability of l-ascorbic acid microencapsulated into taro starch spherical aggregates by spray drying

Abstract

Taro starch spherical aggregates are potential wall material for microencapsulation of biocompounds. The present work considered microencapsulation of l-ascorbic acid into taro starch spherical aggregates. Physical and chemical characteristics of microcapsules, as well as their stability were assessed. SEM images showed spherical microcapsules produced by the aggregation of starch granules. The range Dx50 of the particle size distribution was 14.5 μm for microcapsules and 18.7 μm for taro starch spherical aggregates. The effective encapsulation efficiency was as high as 20.9%. ATR-FTIR spectrum indicated the formation of hydrogen bonds between l-ascorbic acid and starch granules surface. The degradation rate was in the range from 0.006 (13% RH) to 0.029 (72% RH) at 55 °C. The Arrhenius parameters estimated from non-linear regression were A=1.5 and Ea=15.6 kJ∙mol−1. The minimum integral entropy was observed in the activity water range 0.3–0.4 for storage temperatures between 25 and 45 °C. Taro starch spherical aggregates have the ability of retaining and preserving l-ascorbic acid at different humidity and temperature conditions.