Effect Of Germination On Gluten Protein Content And Wheat Flour Quality

In this paper,we studied the differences in the extraction of gluten proteins from wheat,rye,and barley.Meanwhile,the changes in gluten protein content,dough gelatinization and rheological properties,and steamed bread quality during wheat germination were also conducted.The main results are as follows:1.For wheat,60% and 70% ethanol extraction showed the highest protein concentration,and the concentration of isopropanol/DTT two-step extraction was higher than that of one-step extraction.In the H₂O-Na Cl-ethanol three-step extraction method,water bath extraction under 60?conditions had the best extraction effect.for barley,the highest protein concentration was extracted by cocktail extraction,60%and 70%ethanol extraction,the worst effect was H₂O-Na Cl-ethanol three-step extraction.for rye,the concentration of water bath extraction method was the highest under 40?conditions,and the concentration of isopropanol/DTT two-step extraction method was higher than that of one-step extraction method.2.The SDS-PAGE map of gluten protein in wheat,barley and rye showed that the extraction effect of 70%ethanol on high molecular weight glutenin?HMW?in wheat was poor,the extraction effect of cocktail and 70%ethanol extraction on HMW in rye was poor,and the extraction effect of isopropanol/DTT method on HMW was obviously better than that of other methods.The H₂O-Na Cl-ethanol three-step water bath at 60?extraction method and isopropanol/DTT two-step extraction were finally selected as the extraction method for subsequent study.3.The germinating wheat was divided into six stages:bubbling,revealing,germination,bud length 1/4,bud length 1/2 and bud length=grain by the change of appearance and morphology during wheat germination.With the deepening of germination,the content of crude protein in wheat flour decreased gradually,16 kinds of amino acids decreased gradually,the composition of gluten protein did not change significantly;the content of gluten protein measured by R5 ELISA decreased gradually with the deepening of germination degree;the relative content of?-/?-gliadin that containing the most sensitized peptides decreased significantly from the germination state,the relative content of?-gliadin increased significantly,the relative content of?-gliadin,HMW-GS and LMW-GS did not change significantly.4.As the degree of germination deepened,the peak viscosity,minimum viscosity,final viscosity,gelatinization temperature and peak time of wheat flour decreased first and then increased,then decreased continuously,reaching the maximum value in the revealing stage;the disintegration value increased first and then decreased;and the germination value decreased significantly,indicating that the gelatinization characteristics of wheat flour in the revealing stage were better than those of wheat flour without germination treatment.5.With the deepening of germination degree,the water absorption rate of wheat flour increased first and then decreased,the formation time and stabilization time decreased gradually,the thermal stability of starch gelatinization,the hydrolysis rate of starch and the regrowth characteristics of starch decreased significantly after germination.The results showed that the initial germination had little effect on the rheological properties of wheat flour.6.As the degree of germination deepened,the specific volume of steamed bun decreased first,then increased,then decreased,and the germination stage reached the maximum value,indicating that moderate germination was beneficial to increase the specific volume of steamed bun;the whiteness of steamed bun decreased gradually with the degree of germination;the TPA test of steamed bun in revealing stage had no significant difference with unbroken wheat.The results showed that the texture quality of steamed bun did not decrease significantly in revealing stage,and mild germination did not lead to a significant decrease in sensory score.