Effects Of Gluten On The Quality Of Chinese Steamed Bread

Wheat gluten is extracted and separated from wheat flour.Then,using the solubility properties of wheat protein,glutenin(Glu)and gliadin(Gli)were separated from wheat flour.Through controlling the ratios of Glu and Gli precisely,the effects of Glu/Gli on the dough properties of wheat flour and the qualities of Chinese steam bread were studied.Finally,make a preliminary exploration of why Glu/Gli affects dough properties and the quality of Chinese steam bread.The main results are shown as follow:Glu/Gli has great effects on the basic indexes and dough rheological properties of wheat flour.The results show that with the increase of Glu/Gli,the basic indexes and dough rheological properties of wheat flour show regular changes and significant differences.Increasing Glu/Gli can reduce the ability of wheat flour to form gluten,but it can improve the quality of gluten.The gelatinization characteristics show that increasing Glu/Gli can indirectly improve the stability and anti-aging ability of starch in wheat flour.The farinogram showed that increasing Glu/Gli increased wheat flour strength and agitation resistance in a certain range.The extensogram and alveogram showed that increasing Glu/Gli decreased the extensibility and increased the toughness of dough,but too high Glu/Gli made the dough unable to form film.The fermentation characteristics showed that high proportion of Glu reduced the ability of gluten structure to retained gas.Increasing Glu/Gli will enhance the dough's ability to retain moisture to varying degrees,but when the Glu ratio is too high,the dough's ability to retain semi-bound water decreases.Glu/Gli also has significant effects on the quality of Chinese steamed bread.With the increase of Glu/Gli,the specific volume of steamed bread decreased continuously,the ratio of height to diameter increased significantly,and the color changed from bright white to dark yellow.The texture characteristics showed that the hardness and chewiness of steamed bread increased first and then decreased,the cohesiveness and adhesiveness decreased,the resilience increased slowly,and the springiness did not change.The mean of air holes increased first and then decreased,and the mean area of air holes decreased first and then increased slowly;The sensory evaluation showed that the surface structure,internal structure,toughness and viscosity of steamed bread increased first and then decreased,and the taste was not affected.According to the measurement of the relevant indexes of steamed breads and comparison with steamed breads made from commercially available steamed bread special flour,the range of Glu/Gli is basically determined to be about 0.83?1.00,and the steamed breads have the best quality.By means of electron microscope scan,dynamic rheological tests,internal force measurement,FTIR infrared spectrum and fluorescence spectrum,it is concluded that the range of Glu/Gli is 0.83?1.00 and the microstructure of dough is better.Dynamic rheological tests showed that all gluten proteins showed the characteristics of solid-like weak gel,and the deformation in their linear range was compressible and restored.For the functional properties of protein,increasing Glu/Gli will make the water holding capacity of gluten stable first and then increase,and the foaming,foaming stability and surface hydrophobicity decrease.In the gluten structure,the disulfide bond and hydrogen bond are significantly increased,and the ionic bond and hydrophobic interaction are significantly reduced.Both the ?-helix ratio and ?-turn ratio decrease,and ?-sheet ratio shows an increasing trend.The increase of tryptophan groups on the surface of gluten results in the red shift of fluorescence spectrum.The change of disulfide bond in steamed bread is similar to gluten.There was no significant difference in ?-helix,?-sheet and ?-turn of protein in steamed breads,but the irregular curl showed fluctuating increase.