PH-shifting Method Modulates The Co-assembly Behavior Of ?-conglycinin For High-efficiency Loading Of Curcumin

A large number of bioactive substances have a variety of physiological effects and their health benefits have been widely recognized.It is highly recommended to add such substances to food formulations.Curcumin is a hydrophobic natural polyphenolic small molecule compound with a variety of potential health effects and high biosafety,which has great potential to be used as an active ingredient in functional foods.However,the problems of low water solubility,poor stability and low bioavailability of curcumin need to be solved.The use of food colloidal delivery technology to break the bottleneck of curcumin application is one of the most effective strategies.In this paper,soy protein,a bulk plant protein,was used as the delivery carrier matrix.Combined with the principles of disassembly and reassembly of ?-conglycinin and the pH-dependent water solubility of curcumin to successfully prepare highly loaded,highly stable,and better bioavailable curcumin nano aqueous dispersion.The main findings are as follows.The pH-shifting method was used to regulate the dissociation and reassembly of ?-conglycinin.Firstly,the physicochemical and structural properties of ?-conglycinin during the shift process were examined.Then the co-assembly loading of curcumin was performed under the conditions of optimal recombination protein particle state.The optimal conditions were as follows: 10 mg/m L of protein solution was dissociated at pH 12 for 1 h,and then 4 mg/m L of curcumin was added to protein solution for 1 h.Finally,the mixed solution was retuned to pH7 using hydrochloric acid to obtain ?-conglycinin nanoparticles loaded with curcumin,and the loading capacity could reach 22.49 g curcumin/100 g ?-conglycinin.The thermal stability,digestive stability and bioaccessibility of curcumin were significantly improved after encapsulation.The potential mechanisms of action of polyacids on the functional properties of proteins,such as cross-linking and hydrophobicity enhancement,were further exploited.Using citric acid and phosphoric acid for pH adjustment,both ternary acids were found to be successful in preparing ?-conglycinin/curcumin co-assemblies,and the properties of the co-assemblies formed by the three acid compounds(hydrochloric acid,citric acid and phosphoric acid)were compared.All three co-assembled nanoparticles had good colloidal physical stability,and the thermal stability and bioaccessibility of curcumin were significantly better than that of free curcumin,while small differentiation existed among the three.The loading capacity of the citric acid and phosphoric acid groups was significantly higher than that of the hydrochloric acid group,and the loading capacity of the co-assembled carrier formed by citric acid was up to29.59 g of curcumin per 100 g of protein,which was the highest among the three,with an increase of 32% compared to that of hydrochloric acid.The above results suggest that the pHshifting method can be applied to construct a class of highly loaded,stable and bioavailable curcumin delivery system,and the properties of the co-assembled carriers can be effectively regulated by changing the acid regulator.