| Pickering emulsion is a new kind of emulsion stabilized by solid particles as emulsifiers instead of traditional chemical surfactants, which is superior for application in food, pharmaceutical and cosmetics because of its strong interfacial stability and resistance to Ostwald ripening compared with traditional emulsion. In this research, edible starch nanocrystals(SNC) were chosen as emulsifier to stabilize O/W Pickering emulsion, and the stability and digestion characteristics of emulsion were studied. The creaming stability of emulsion and regulated digestion of lipid were improved by adding polysaccharides. Eventually, stable Pickering emulsion delivery system would be established and the research would provide theoretical basis for the application of this system in food and pharmaceutical.At first, Pickering emulsions incorporating three typical edible lipids with different fatty acid chain: short, medium and long chain triacylglycerols(SCT, MCT and LCT) were fabricated by adjusting the SNC concentration and oil volume fraction. With the SNC concentration increasing, the particle size of Pickering emulsions decresed to a certain value around 25 μm when the SNC concentration was 1 wt%; with the oil volume fraction increasing, the stability of Pickering emulsions decreased, but no phase inversion occurred. Besides, the Pickering emulsions incorporating SCT could effectively inhibit the Ostwald ripening. The particle size of Pickering emulsions with optimized concentration containing 1wt% SNC and 0.5(v/v) oil were 24.65±1.46 μm, 26.27±0.18 μm and 26.60±0.81 μm respectively, which showed high store stability at room temperature at least for 90 days. During in vitro digestion process, the rate of lipid digestion was increased in the order of LCT<MC T<SCT, whereas the percentage o f SNC digested was decreased in the order of LCT>MC T>SCT. The results may be related to digestion of lipid and the interaction between calcium and SNC, free fatty acid released from lipolysis or bile salt.The research was carried out to choose quaternary chitosan(QCS) and alginate(Alg) as cosurfcant to improve the crea ming stability of Pickering emulsion. And the influence on digestion characteristics of emulsion was investigated. The results showed that cationic quaternary chitosan was interacted with SNC through hydrogen-bonding interaction and electrical attraction, and anionic alginate was interacted with SNC through hydrogen-bonding interaction. The smallest droplet of emulsions was acquired when the concentration of quaternary chitosan and alginate were 0.4 wt% and 0.2 wt%, respectively. The particle size of emulsion stabilized by QCS/SNC and Alg/SNC were 27.43±0.25 μm and 22.88±0.52 μm without creaming even after a period of 90 days storage at room temperature. During in vitro digestion process, FFA released of Pickering emulsions stabilized by QCS/SNC and Alg/SNC were 68.65±1.86% and 45.58%,and the SNC digested were 46.29±1.72% and 40.81±0.81%. The results showed that FFA released was increased because the addition of quaternary chitosan, whereas it could be reduced because of alginate, and both of polysaccharide could inhibit the SNC digestion.Aim at controlling the extent of lipid digestion, multi-compenent biopolymer coatings were formed around lipid droplets by using an interfacial electrostatic deposition approach. And the multilayer emulsions were fabricated through the adsorption of anionic polysaccharide alginate and pectin on the surface of droplets of Pickering emulsion stabilized by QCS/SNC. The influence of anionic polysaccharide concentration and p H in solution on the stability of multilayer emulsions were studied. The results showed that the stable multilayer emulsions were acquired when the concentration of anionic polysaccharide was 0.1 wt% from p H 2 to 7. And the particle size of emulsion stabilized by SNC+QCS+Alg and SNC+QCS+Pectin were 31.44±1.12 μm and 30.13±2.61 μm, which showed high store stability at room temperature at least for 90 days. During in vitro digestion process, FFA released of Pickering emulsions stabilized by SNC+QCS+Alg and SNC+QCS+Pectin were 55.07±1.28% and 49.89±0.82%, and the SNC digested were 38.74±0.54% and 42.47±1.51%.The results showed the digestion of Pickering emulsion delivery system could be controlled by coating the lipid droplets with multilayer biopolymer coating. |
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