Co-assembly Structure Of Rice Protein And Soybean Protein And Improvement Of The Physicochemical Properties

Rice proteins(RPs),as a by-product of rice starch,has the advantages of high nutritional value and hypoallergenic.However,due to the large amount of disulfide bonds and hydrophobic amino acids in rice glutelins(RGs),the water solubility of rice protein is poor,which hinds its high value-added utilization.Soybean protein isolates(SPIs)are the most widely used proteins.β-conglycinin(7S)and glycinin(11S)of soybean globulin(SGs)in SPIs have different hydrophilic and hydrophobic properties,such as high emulsification of 7S.Based on the previous research,the co-assembly structure of RPs and SPIs(RPs-SPIs)was constructed by p H-cycle technology to improve the solubility of RGs while improving its physical and chemical properties.In the process,the co-assembly mechanism of RGs with different ratios of SGs was explored.In order to further improve the rigidity of air-liquid interface,the binding mechanism of RPs-SPIs and starch nanocrystals(SNCs)was elucidated.This study aims to clarify the co-assembly mechanism of RPs and SPIs,and contribute to the high value application of RPs.The specific research contents are as follows:Mechanism of interaction between components of RPs and SPIs.The main components of RPs(RGs)and SPIs(7S and 11S)were separated,and the co-assembled structures of RGs-7S and RGs-11 S were obtained by p H-cycle.Fluorescence spectra,far-ultraviolet circular dichroism,dynamic light scattering and morphological characterization showed that both 7S and 11 S formed co-assembled structures of 80～120 nm through hydrophobic interactions with RGs.RGs-7S has stronger resistance to acid-induced folding than RGs-11 S co-assembly.The solubility of RGs-7S and RGs-11 S are up to 93.3% and 91.2%,and they both have good emulsifying ability and foaming ability.The foaming ability of RGs-11 S is improved by 3 times and the emulsifying ability is improved by 2 times compared with 11 S.Study on interface characteristics and improvement of RPs-SPIs co-assembly.Under the optimal mass ratio of RPs-SPIs(1:1),the three-phase contact angle of RPs-SPIs at the water-oil interface is 89°,and the contact angle of air-liquid is 80°,so it has characteristics of Pickering particles.RPs-SPIs improved the solubility of RPs and made it have better physical and chemical properties.RPs-SPIs can form a stable O/W emulsion in the range of0.5%～2.5% protein concentration.The foaming ability of RPs-SPIs was up to 180%,60%higher than that of SPIs.However,stability of the foam of RPs-SPIs needs to be improved.In this study,SNCs was used to strengthen the foaming stability from 30 min to more than 12 h.In conclusion,the RPs-SPIs co-assembled structure has better solubility,nutritional properties and functional properties.RPs-SPIs is a potential emulsifier and foaming agent with appropriate interface structure behavior at oil-water and air-liquid interfaces.SNCs can significantly improve the stability of RPs-SPIs at the air-liquid interface,leading to the development of liquid bubbles with long-term stability.This study provides important research ideas and theoretical basis for the application of rice protein and soybean protein in food industry.