Characterisation of O/W emulsions encapsulating ergocalciferol using onion skin waste saponins: insights on formulation and release properties

Abstract

The study was conducted to produce ergocalciferol (Vit-D2) loaded oil-in-water (O/W) emulsions utilising the onion skin waste saponins (OSW) as a natural emulsifier and almond oil as carrier oil. The impact of different formulations upon the digestibility of lipids, LCT (long-chain triglycerides) or MCT (medium-chain triglycerides), and bioaccessibility of Vit-D2 was analysed. The mean particle size diameter of almond oil-based O/W emulsions was decreased with increasing homogenisation pressure and emulsifier concentration. During 120 mins of digestion in small intestinal fluids (SIF), almond oil in high-lipid emulsions (5% w/w) was not fully digested, resulting in a lower bioaccessibility of ergocalciferol than low-lipid samples. Almond oil emulsions with larger particle size have a slower rate of lipid digestion than the smaller size particles, but the release rate of free fatty acids was constant throughout the digestion process. Moreover, almond oil emulsions showed similar Vit-D2 bioaccessibility to the oil-based emulsions but were much higher than MCTs.