Use of zein-pullulan particles in the encapsulation of vitamin D (cholecalciferol) by the Pickering emulsion method, its effect on in vitro digestion and release properties

In this study, vitamin D, a vitamin affected by unfavorable environmental conditions during food processing, storage and gastrointestinal digestion, was encapsulated by the Pickering emulsion method. The effects of biopolymer zein-pullulan particles and small molecular weight emulsifiers on emulsion formation, stability and rheology were investigated. The potential use of Pickering emulsions in vitamin D encapsulation was investigated by encapsulation efficiency and in vitro digestion studies and the release profiles and release mechanisms during in vitro digestion were elucidated. According to the dynamic interfacial tension analysis, the zein-pullulan particle dispersion applied at pH 10 reduced the oil-water interfacial tension more than the particle dispersions applied at pH 2-4-6-8. The emulsion prepared with this particle dispersion exhibited high absolute zeta potential (30.94±0.45 mV) and low creaming index (10.39±0.05%) compared to others. The use of pullulan in particle dispersions increased emulsion stability by improving steric repulsion and three-dimensional network structure formation. Increasing pullulan concentration decreased the flow behavior index and increased the consistency index. The combined use of zein-pullulan particle dispersions and small molecular weight emulsifiers (saponin and/or Tween 20) in emulsions improved the interfacial properties, reduced the emulsion droplet size and decreased the flow behavior index. The use of saponin increased the consistency index, while the use of Tween 20 decreased it. No change was observed in the emulsion droplet morphology of these samples during 28 days of storage, temperature, ionic strength and pH stability studies. In vitamin D encapsulation studies, emulsions prepared with particle dispersions containing pullulan exhibited higher encapsulation efficiency than those prepared without pullulan. Emulsions using zein-pullulan particle dispersions and small molecular weight emulsifiers together exhibited the highest encapsulation efficiency. The use of pullulan in particle dispersions decreased the amount of vitamin D incorporated into the micelle phase during in vitro digestion, thus reducing bioaccessibility. The combined use of zein-pullulan particle dispersions and small molecular weight emulsifiers increased bioaccessibility. It was shown that emulsifiers have an effect on the release profile and the release of bioactive components can be directed by the selection of emulsifier.