Study On The Co-encapsulation Of Bioactive Components Based On Emulsification/Gelation Of Whey Protein Isolate

With the improvement of nutrition awareness,the demand for functional foods with a variety of health benefits is increasing.Co-encapsulation of multiple nutritive active components is not only beneficial to the synergistic effect of active components,but also may maintain the long-term stability of active ingredients,which has attracted more and more research interest.At present,co-encapsulation of active components with different solubility is difficult.Multiphase systems based on protein are gradually being applied to co-encapsulation of active components with different solubility.Whey protein isolate（WPI）has emulsification,gelation and other functional properties,and has been used for the encapsulation of a single active component.It is possible to realize co-encapsulation of active components by using its various properties for assembly.In this thesis,based on emulsification and gelation of WPI,hydrophobicα-tocopherol,hydrophilic L-ascorbic acid（which can regenerateα-tocopherol and synergistic antioxidant）and amphiphilic resveratrol（which can regenerateα-tocopherol）were selected as the encapsulation model of nutritive active components,to achieve the encapsulation of active components with different solubility,and the main research contents and results are as follows:First,based on the emulsion filled gel prepared previously by our research group,the co-encapsulation ofα-tocopherol and resveratrol was studied.In emulsions stabilized by heat denatured WPI,the total encapsulation efficiency of resveratrol was 59%-63%,and the total encapsulation efficiency ofα-tocopherol is about 98%.In emulsion filled gels,α-tocopherol and resveratrol can be completely encapsulated.Under simulated digestion conditions,the disintegration of gel network was the main factor affecting the release of active components,and the increase of both Ca²⁺concentration and oil content could delay the release of active components.It was found that the two released nutritive active components were stable in the simulated gastric juice and degraded in the subsequent simulated intestinal juice.Compared with the single encapsulated cold-set gel system,resveratrol was found to protectα-tocopherol by its own loss in co-encapsulated emulsion filled gels.After the gel digestion,the retention rate of released resveratrol was more than 50%,while the retention rate of releasedα-tocopherol remained at about 25%.Then,Water in Oil in Water（W/O/W）emulsions containing gelled internal aqueous phase were designed and constructed in terms of preparation process and formulation,and the co-encapsulation of L-ascorbic acid andα-tocopherol was studied by using them.By analyzing particle size distribution and micro-images of emulsions prepared by shearing,extrusion and different premixed membrane emulsification under ice water bath,the results showed that W/O/W emulsion with controllable particle size could be prepared by using the premixed membrane emulsification through T-channel and extrusion module after shearing twice and extrusion.When gelling the internal aqueous phase of emulsion based on the gelation property of WPI,two kinds of hydrogel formulations were obtained by adjusting the amount of L-ascorbic acid and Na⁺concentration.Further co-encapsulation ofα-tocopherol,it was found that particle size and internal hydrogel were the main factors affecting the encapsulation efficiency of L-ascorbic acid in emulsions,while the encapsulation efficiency ofα-tocopherol in the emulsion was>96%.In addition,when changing the external aqueous phase of emulsion,the encapsulation efficiency and stability of L-ascorbic acid were not affected,but the stability ofα-tocopherol could be significantly improved when emulsion stabilized by WPI-pectin.Storage temperature was a key factor affecting the stability of active components in W/O/W emulsion containing gelled internal aqueous phase.So,in W/O/W emulsion containing gelled internal aqueous phase,active components were relatively stable at 4℃,and degraded significantly at 25℃for 15 days.The results provide more experimental data and suggestion for the co-encapsulation design and development of multiple nutritive active components based on whey protein.