| Resveratrol pocesses antioxidant,anti-inflammatory,anti-cancer,cardio-protective and neuro-protective abilities,but the fact that it also has low water solubility,poor stability,and easy degradation under the influence of oxygen,light,heat and low p H and so on,limits its application in the food or drug industry.In order to improve the stability of resveratrol,Ovalbumin-Dextran（OVA-DEX）conjugates were prepared by dry-heating Maillard reaction.The structure and functions of the conjugates were evaluated.Then,Resveratrol emulsion was prepared by using OVA-DEX conjugates as embedding material.The storage stability,physicochemical stability,antioxidant property and biological accessibility of the emulsion were investigated.Firstly,six OVA-DEX conjugates（formed by OVA’s glycosylation with six kinds of DEX of different molecular weights respectively）were prepared and characterized.Effects of DEX’s molecular weight on OVA-DEX conjugates’physicochemical properties（including grafting degree,molecular weights of obtained conjugates,emulsifying capacity,emulsifying stability,thermal stability and hydration dynamic particle size,etc.）were evaluated by SDS-PAGE electrophoresis,grafting degree,Fourier Transform Infrared spectroscopy,and endogenous fluorescence and so on.Results showed that:the smaller the molecular weight of DEX was,the easier it could covalently bind with OVA;covalently binding of DEX could change the secondary structure composition of OVA,and grafting degree was consistent with Maillard reaction time;the emulsification of OVA-DEX conjugates（72-hour Maillard reaction products）increased at first and then decreased with the increase of molecular weight of grafted DEX,and the emulsification stability increased with the increase of molecular weight of DEX.Compared with OVA,the surface hydrophobicity of OVA-DEX conjugates decreased;and the surface hydrophobicity of OVA-DEX conjugates decreased gradually with the increase of Maillard reaction time,and decreased first and then increased with the increase of DEX molecular weight.With the increase of grafting degree and DEX molecular weight,the hydrodynamic particle size of conjugates gradually increased,and more stable in thermal environment.Secondly,prepared OVA-DEX conjugates were used to encapsulate resveratrol to form Pickering emulsion.The stability of Pickering emulsion was analyzed by particle size,PDI,turbidity value,resveratrol residual content,and rheological properties.The influence of Pickering emulsion on the antioxidant performance of resveratrol was evaluated by ABTS cation radical scavenging ability.Results showed that:OVA-DEX could encapsulate resveratrol and form uniform Pickering emulsion,and had better performance for stabilizing resveratrol compared with OVA.Among those conjugates,OVA-DEX1k had the highest encapsulating rate and the best storage stability at 4℃up to 28 days.However at50℃up to 28 days,the stability of the resveratrol emulsion encapsulated by OVA-DEX10k and OVA-DEX 70k was better.Under the influence of Na+concentration（1 mol/L-5mol/L）,sucrose concentration（2%-20%）and p H（3.0-9.0）,the stability of the emulsion was improved by OVA-DEX conjugates,and among them OVA-DEX1k was the most stable one.Results of simulated gastrointestinal digestive analysis showed that:compared with OVA,Pickering emulsion of OVA-DEX conjugates can effectively improve the tolerance of resveratrol to simulate gastric digestion,improve its retention rate,and then improve the bioaccessibility of resveratrol.Among them,the bioaccessibility of resveratrol in Pickering emulsion formed by encapsulation of resveratrol with OVA-DEX1k is the highest. |
