| 7S and 11S components of Soybean storage protein account for about 70% of the total soybean protein and play an extremely important part in the nutritional quality and physiological function of soybean protein.On account of the wide and large range of phenotypic variation in the relative contents of 7S and 11S components and their subunits in different soybean germplasm resources,and there is a extremely significant negative correlation between the contents of 7S and 11S components,the deletion and content of 7S and 11S protein subunits,and the changes in 11S/7S ratio are great significance for improving the nutritional and processing properties of soybean protein itself.In this study,firstly,the contents of 11S and 7S components of storage proteins in 725 soybean germplasm are accurately determined using indirect competitive enzyme immunoassay(Enzyme-link immunosorbent assay,ELISA).Then,the variation patterns of 7S and 11S components in different germplasm,the correlation between each protein component and the geographical origin,total protein content,fat content,growth period and 100-grain weight of soybean germplasm are comparatively analyzed.Finally,the relationship between the 7S and 11S component and their subunit relative contents of raw soybean and the quality characteristics of soybean protein processing is discussed in depth.The experimental results show that:1.Different soybean 7S and 11S contents have rich genetic variation.The contents of 7S and 11S components in 725 soybean germplasm are measured by indirect competitive ELISA.The contents of 7S components range from 40.85 mg/g to 234.24 mg/g with an average of136.66 mg/g and coefficient of variation 24.50%.The content of 11S component range from47.66 mg/g to 249.14 mg/g with an average of 154.31 mg/g and coefficient of variation of23.18%.Among the 725 materials,one cultivar with 7S content up to 234.24 mg/g,Dongnong50,is screened and another cultivar,Williams79,with 7S content as low as 40.85 mg/g is screened out.A variety with 11S content of 249.14 mg/g,Zhechun 3 is selected,and We also screen one variety with only 47.66 mg/g of 11S-He95-923,one variety with 5.17% of 11S/7S-Williams 79.2.There is a highly significant negative correlation between the contents of soybean storage protein 7S and 11S(r=-0.907,n=725),but there is no significant correlation between the contents of soybean storage protein 7S and 11S and the contents of total protein and fat of soybean germplasm.This indicates that there is great development potential to breed new varieties with high content of 7S and 11S components that do not affect their total protein content and high-quality fatty acid content.The contents of 7S and 11S components have no significant correlation with the fertility period and 100-grain weight of soybean germplasm.The genetic variation between the 7S and 11S components of soybean germplasm is not significantly correlated with the geographic origin of soybean cultivation,and is related to the degree of genetic relationship difference of soybean from different sources,according to the experimental clustering results and the analysis results of different geographical sources.3.According to the 11S/7S ratio,grain integrity rate and the degree of damage in appearance,materials with large kernels,high protein,well-preserved seed coat and no disease spots are screened out,which are made correlational analysis of the processing quality of soybean germplasm and 11S/7S ratio.The ratio of 11S/7S increases non-linearly from soybean seeds to tofu samples.The 11S/7S ratio of the test seeds ranges from 1.61 to 1.86,and the11S/7S ratio of the manufactured tofu ranges from 1.63 to 3.08,which is related to the difference in the thermal stability of 7S and 11S globulin in the process of tofu production.The hardness of tofu protein gel is highly significant and positively correlated with the ratio of11S/7S(r=0.99).and the higher the 11S/7S ratio within a certain range,the harder the tofu made from soybean seeds.Soybean grain 11S/7S ratio is positively correlated with yield(r=0.89)and soymilk p H value(r=0.90).α’ and α-subunit contents of 7S globulins greatly affecte the extraction rate of soluble protein and yield of tofu.The genotype with higher content ofβ-subunit in soybean seeds 7S globulin has great impact on the texture and apparent properties of tofu.Tofu made from soybean seeds with higher content of β-subunit has softer texture,more holes in gel network structure,and cavities in tofu matrix. |
