Microencapsulated ascorbic acid: Development, characterization, and release profile in simulated gastrointestinal fluids

Abstract

The aim of this study was to produce ascorbic acid (AA) microcapsules by complex coacervation, characterize them, and evaluate the release profile in simulated gastrointestinal fluids. The microcapsules were made of gelatin and pectin at concentrations of 1.0, 2.0, and 3.0%. The coacervated microcapsules were assessed for morphology (by optical microscopy and scanning electron microscopy), water activity (Aw), hygroscopicity, solubility, encapsulation efficiency (EE), thermal behavior, and AA release profile. The AA microcapsules were characterized by low solubility, low hygroscopicity, high thermal stability, and low diameter (<10 μm), with EE ranging from 23.7 to 94.3%. The release profile was faster in gastric fluid (pH 1.8) than in intestinal fluid (pH 6.8). The sample containing 2.0% of wall material and 50% (w/w) of the simple emulsion (core) had the highest EE and the best in vitro release profile, with release of only 68% of AA in 120 min in the gastric fluid. PRACTICAL APPLICATIONS: Ascorbic acid (AA) is widely used in the food industry as an antioxidant, but practical use becomes limited due to its high instability. Microencapsulation was proposed as an alternative to increase the stability of this compound. Gelatin and pectin were used as wall materials in the production of ascorbic acid microcapsules by complex coacervation. Both solubility and hygroscopicity were low while the thermal stability of the active material improved with the microencapsulation process. Ascorbic acid release was more pronounced in gastric fluid (pH 1.8) and slower in intestinal fluid (pH 6.8). The results of this study demonstrate that the microcapsules produced represent a feasible method of increasing AA availability in food products, especially for those samples that presented high encapsulation efficiency.