Microencapsulation of vitamin E by gelatin-high/low methoxy pectin complex coacervates: Effect of pH, pectin type, and protein/polysaccharide ratio

Abstract

In this study, gelatin (GA), high-methoxyl pectin (HMP) or low-methoxyl pectin (LMP) were used to prepare complex coacervates, and effect of pectin type, pH, and gelatin-pectin ratio on formation and physiochemical properties of complex coacervates were deeply investigated. Furthermore, vitamin E (VE) was encapsulated using GA-HMP/LMP complex coacervates. The GA-HMP/LMP complex coacervates and GA-HMP/LMP-VE microcapsules were optimized and characterized. At the gelatin-pectin ratios of 2:1 and 3:1 and pH of 4.0, the GA-HMP and GA-LMP had the maximum yield of 54.67 ± 1.82% and 59.33 ± 1.49%, and turbidity of 1.33 ± 0.02 and 1.30 ± 0.04, respectively, and GA-HMP/LMP were close to zero potential at this point, indicating that the strength of electrostatic interaction was strongest. The GA-LMP and GA-HMP displayed spherical and irregular short-rod like appearance, respectively, and more aggregates and denser network were formed at gelatin-pectin ratio of 3:1, especially in GA-HMP3:1. The formation of GA-HMP/LMP complex coacervates was driven by electrostatic interaction, and GA-HMP3:1 had the optimum thermal stability. Except GA-HMP2:1-VE, the prepared and optimized VE mirocapsules by GA-LMP and GA-LMP complex coacervates showed spherical state and uniform particle size. The GA-HMP2:1-VE and GA-HMP3:1-VE possess the highest hygroscopicity and wettability of 109.08 ± 7.66 s and 26.67 ± 0.85 g/100g, respectively. The GA-HMP3:1-VE microcapsules had the highest encapsulation efficiency of 82.67 ± 1.77 %. Results of differential scanning calorimetry and release behavior in hot-water indicated that the microcapsules had excellent thermal stability. Furthermore, the GA-HMP and GA-LMP made VE stable in gastric stages and sustainable release in intestinal stages.