Effect Of Restrictive Enzymatic Hydrolysis Combined With Macroporous Resin Adsorption Decolorization On Processing Characteristics And Structure Of Sunflower Seed Protein

Due to the presence of polyphenols in sunflower seed meal,dark protein is produced when extracting sunflower seed protein,resulting in a decrease in nutritional and functional properties.Therefore,this experiment firstly explored the decolorization process of sunflower seed protein and prepared the decolorized sunflower seed protein.On the basis of this,the effect of decolorization on the processing properties such as solubility,emulsifying,foaming and rheological properties of sunflower seed protein was studied.Automatic amino acid analyzer,?potentiometer,Fourier transform infrared spectroscopy,differential scanning calorimetry,particle size analyzer and scanning electron microscopy to determine the amino acid content,infrared spectrum,particle size distribution,zeta potential and thermal stability of sunflower seed protein before and after decolorization Microstructure,clear effect of decolorization on the amino acid composition and structure of sunflower seed protein.The main findings are as follows:1.Decolored sunflower seed protein with whiteness value up to 86.3 can be prepared by restrictive enzymatic hydrolysis of alkaline protease for 10 min,further using AB-8 macroporous adsorption resin at pH7.0,resin dosage 12%(m/v),adsorption temperature 20? and adsorption time 120 min.2.The solubility,emulsifying property,emulsifying stability,foaming property and foaming stability of sunflower seed protein before and after decolorization at pH3.0?10.0 were further studied.The results showed that under the condition of pH3.0,the solubility of sunflower seed protein decolorized by restrictive enzymatic hydrolysis combined with macroporous adsorption resin was 59.1%,foaming was 17.8%and emulsifying stability was 47.2%higher than that of non-decolorized sunflower seed protein.Under the condition of pH4.0,the processing characteristics of sunflower seed protein before and after decolorization were reduced,and the solubility of decolored sunflower seed protein was improved.Compared with uncolored sunflower seed protein,the processing properties of uncolored sunflower seed protein increased by 26.3%,foaming ability increased by 55.4%,emulsifying stability increased by 31.7%.The processing properties of uncolored sunflower seed protein increased gradually before and after decolorization at pH5.0-10.0,and reached the highest value at pH 10.0.At this time,the solubility of decolored sunflower seed protein increased by 30.2%compared with uncolored sunflower seed protein.The foamability and emulsifying stability were improved by 47.1%and 42.5%respectively.The gel properties of sunflower seed protein before and after decolorization were studied by rheometer under the condition of pH7.It was found that the protein structure of sunflower seed protein was weak when the concentration of protein dispersions was 20%.3.The results showed that decolorization had no significant effect on the amino acid composition of sunflower seed protein,but the amino acid content of sunflower seed protein increased significantly,indicating that decolorization did not affect the nutrient composition of sunflower seed protein.Infrared spectrum analysis showed that the content of alpha-helix structure increased and the content of irregular curl structure decreased in decolorized sunflower seed protein.The results showed that after decolorization,the proportion of medium to large particle size decreased gradually,and the average particle size decreased significantly,from 79.757 ?m to 48.889 ?m and 36.103 ?m,which indicated that decolorization could effectively reduce the particle size of sunflower seed protein.The results of potential showed that the potential of sunflower seed protein decolorized by macroporous resin increased from-29.3 to-43.1,indicating that the solution system was more stable after decolorization.DSC results showed that the thermal stability of decolorized sunflower seed protein was significantly improved,and the denaturation temperature was raised from 298.4? to 302.9?.Scanning electron microscopy(SEM)results showed that decolorization resulted in significant changes in the powder structure of sunflower seed protein,from large and irregular flake structure to small and uniform flake structure.