Microencapsulation of vitamin D in protein matrices: in vitro release and storage stability

Abstract

Stability and preservation of vitamin D are major concerns that lead to its encapsulation. Whey protein isolates (WPI) and soy protein isolates (SPI) were used as a carrier to effectively encapsulate vitamin D. The resultant microcapsules were evaluated for encapsulation efficiency, morphological characteristics, XRD diffraction, gastric release and storage stability. Nine different formulations WPI (6, 8, 10%), SPI (6, 8, 10%) and WPI + SPI (6, 8, 10%) were prepared. Among them, 5% WPI + 5% SPI exhibited the highest encapsulation efficiency (> 95%). SPI microcapsules had a large size as compared to WPI. Scanning electron microscope revealed that the combination of both proteins produced smoother beads with fewer fissures and better retention for vitamin D. The structural changes of WPI and SPI from crystallinity to amorphous confirm vitamin D encapsulation through XRD diffraction. Maximum release was observed in SPI (66–50%) in simulated gastric fluid. All the encapsulates showed significantly higher stability and vitamin D retention (> 93%) during storage at 4 °C as compared to free vitamin D. The present study demonstrates both proteins as a potential carrier to encapsulate lipophilic vitamin.