Investigation of the stability of vitamin D in emulsion-based delivery systems

Abstract

Vitamin D is a nutraceutical agent, which is necessary for good health. However, the sufficient amount of this vitamin needed for daily intake is not found in most foods which leads to many producers choosing to develop vitamin-enriched products. Vitamin D is sensitive to the exposure to oxygen and high temperature. To protect it against degradation during food processing, emulsion-based delivery is preferred. The more stable emulsion leads to higher protection of vitamin D. The present study investigated the effects of different factors, such as the choice of biopolymer, pH, ionic strength, and temperature, on emulsion stability. As emulsions with smaller particles are known to be more stable, the minimum concentrations of the biopolymers under study allowing the minimum size of particles were determined. The results obtained were the following: gum arabic 7 %, 468 nm; maltodextrin 2 %, 266 nm; Whey protein concentrate (WPC) 0.5 %, 190 nm; Soy protein isolate (SI) 4 %, 132 nm. Among the different biopolymers and the emulsion conditions studied, the soy protein isolate emulsion provided the highest protection of vitamin D (85 %) at 4 wt% concentration, pH 7 and 25 °C. SEM analysis of the dried nanocapsules of the soy protein isolate emulsion revealed homogeneous and uniform dispersion of particles.