Study On The Emulsification Of Enzymatic Pea Protein Isolate And Its Storage Properties

Pea protein isolated(PPI)has been widely concerned by researchers for its excellent nutritional value and low allergenicity.Enzymatic hydrolysis of protein can improve its functional properties and bioavailability,and the product can be used to construct food nanoparticle emulsion system to transport active ingredients or nutrients,which has broad industrial application prospects.In this study,pea protein isolate(PPI)was used as raw material,the effects of enzymatic hydrolysis conditions on the emulsification properties of pea protein hydrolysate(PPH)were studied,and the degree of hydrolysis of PPI and DPPH.scavenging rate of the PPH were also investigated.The relationship among the emulsification characteristics and DPPH.scavenging rate of hydrolysate and the degree of hydrolysis of PPI was established.The products were classified with ultrafiltration and analyzed for structure characteristics.The effect of graded components on the functional properties of PPI enzymatic hydrolysis products was explored.Furthermore,the effects of cellulose and pectin on the physical properties and microstructure of emulsion of PPI enzymatic hydrolysis products during storage were studied.This was expected to develop a stable performance of emulsions,and provide a theoretical basis for the application of PPI in the food industry.(1)Effects of enzyme type and enzymatic hydrolysis conditions on DH of PPI,EAI,ES,and DPPH.scavenging rate of enzymatic hydrolysis products were investigated.The results showed that enzymatic hydrolysis products with alcalase,flavourzyme and pepsin had better emulsification characteristics and DPPH.scavenging rate.Proper regulation of enzymatic conditions could improve the emusifying properties of PPI.The ES of enzymatic hydrolysis products with flavor proteases showed a significant positive correlation with DH and DPPH.scavenging rate(0.757*和 0.892**).The ES of enzymatic hydrolysis products with pepsin showed a significant negative correlation with DH(-0.953**).(2)The structural characteristics of pea protein hydrolysate(PPH)and their ultrafiltration components were studied.The results showed that the components of alkaline and flavor protease hydrolysates were concentrated below 1 k Da,and the proportion of pepsin hydrolysates larger than 10 k Da was 15.29%.The amino acid composition of PPH were similar to that of PPI.According to the analysis of contact angle and fluorescence spectra,the contact angle of PPI was larger than that of PPH.The contact angle of ultrafiltration components was increased with the increasing of molecular weight.Compared to PPI,the fluorescence spectra of PPH were red-shifted,and their fluorescence intensity increased.The order of fluorescence intensity was A1<A2<A3<A4,F1<F2<F3<F4,P1<P2<P3<P4 for ultrafiltration components.The larger molecular weight components(A4,F4 and P4)of the three enzymatic hydrolysis products play a major role in their emulsification properties.(3)The storage characteristics of enzymatic hydrolysis products emulsion were investigated.The results showed that the particle size of PPI-Cellulose(PPI-C)and Pepsin enzymatic hydrolysis product-High methoxy pectin(P-H)emulsions were small.The above systems were stable and no obvious stratification was observed.Enzymatic hydrolysis products-Cellulose,PPI-High methoxy pectin(PPI-H),and enzymatic hydrolysis products of flavor proteases-Pectin emulsions showed shear thinning behavior.P-H emulsions had the lowest viscosity.The results of optical and laser confocal microscopy indicated that the droplets of PPI-C emulsions were smaller and evenly dispersed during storage.The droplets of enzymatic hydrolysis products of alkalase and flavor proteases-cellulose emulsions were large,and increased obviously with the extension of the storage time.The droplets of enzymatic hydrolysis products of pepsin-cellulose emulsion was small,but its flocculation phenomenon was more serious.The oil droplets of alkalase and flavor proteases enzymatic hydrolysis products-pectin and PPI-H emulsions aggregated during storage.Oil droplets of P-H emulsion was more dispersed and the system was relatively stable.The results provide a theoretical basis for expanding the application of PPI in the food industry.