Encapsulation of fruit peel proanthocyanidins in biopolymer microgels: Relationship between structural characteristics and encapsulation/release properties

Sodium alginate was used to fabricate biopolymer microgels to encapsulate two proanthocyanidins (PAs) fractions (F1 and F2) isolated from Choerospondias axillaris (C. axillaris) fruit peels. The impact of the molecular mass of the PAs on their entrapment efficiency and release profile was then established. Additionally, the antioxidant and prebiotic activities of the two PA fractions were investigated. The F1 fraction mainly contained oligomers, while the F2 fraction contained higher molecular weight polymers. Both F1 and F2 fractions exhibited strong antioxidant and prebiotic activities at certain concentrations. The entrapment efficiency of F1 and F2 fractions in alginate beads were 43.4 ± 3.2% and 62.2 ± 4.1%, respectively. The entrapment of the F2 fraction was significantly higher than that of the F1 fraction (p < 0.05), which was attributed to its higher molecular weight. The release of the F2 fraction from the alginate beads was marked slower than the F1 fraction, in both water and simulated gastrointestinal conditions, indicating that PAs with higher molecular weight have the potential for creating prolonged release systems. This study highlights the importance of selecting nutraceuticals with appropriate molecular characteristics to obtain good entrapment efficiency and release properties.