Gallic acid (GA) was encapsulated with native (NIn), cross-linked (CIn) and acetylated (AIn) inulin by spray-drying. Inulin microparticles were characterized by encapsulation efficiency (EE) and their release profile in yogurt. The EE was significantly higher for GA-CIn (98%) compared with GA-NIn (81%) and GA-AIn (77%) microparticles, showing the effect of the modification of inulin on interaction of GA-polymer. GA release profile data in yogurt for GA-CIn, GA-NIn and GA-AIn were fitted to Peppas and Higuchi models in order to obtain the GA release rate constant. Although the GA release rate constants were significantly different among systems, these differences were slight and the GA release was fast (80% < 2 h) in the three systems, showing that inulin-systems did not control GA release in yogurt. The mechanism of GA release followed a Fickian diffusion and relaxation of chains for all microparticles. According to the release profile, these microparticles would be best suited for use in instant foods.
Keywords: gallic acid; microencapsulation; release profile; spray-drying; yogurt.
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