Effects Of Konjac Glucomannan On The Characteristics Of Frozen Gluten Protein And The Quality Of Frozen Steamed Bread

Konjac glucomannan(KGM)is a polymer heteropolysaccharide linked by glucose and mannose with β-1,4 glycosidic bonds,which has important economic and medicinal value.In recent years,there has been some progress in the application of KGM as a food additive in pasta products,and there are few studies on the application of KGM in frozen dough.The frozen wheat protein fractions,gluten,gliadin and glutenin fractions were extracted from wheat flour,and SDS-PAGE gel electrophoresis,Fourier transform infrared spectroscopy,UV-visible spectrophotometer,scanning electron microscope,differential calorimeter,rheometer were used to characterize them in detail.The structure and properties of molecular weight,secondary structure,free sulfhydryl,microstructure,rheological properties and thermal variability were analyzed to reveal the mechanism of KGM protection against gluten from the perspective of composition.On this basis,the important effect of KGM on the quality of frozen dough was confirmed by the frozen dough system,and the effectiveness of the mechanism was confirmed by the quality measurement of steamed bread.The research results are as follows:1.The effects of KGM on the molecular weight,free sulfhydryl groups,secondary structure and microstructure of gluten,glutenin and gliadin during freezing were studied.The results showed that KGM can increase the content of gluten and gliadin free sulfhydryl groups.When the KGM substitution rate was 2.5%～4.5%,the gluten free sulfhydryl content increased by 0.13,0.58,0.52 and 0.61μmol/g,respectively;the gliadin free sulfhydryl content increased by 0.19,0.67,0.99,0.89 and0.78μmo L/g,respectively.The free sulfhydryl content of glutenin decreased by 0.16,0.23,0.35,0.58 and 0.83 μmol/g,respectively.SEM images showed that after adding KGM,the microstructure of three protein fractions had a spongy appearance with larger pores.2.To study the effects of KGM on water,thermal properties and rheology of gluten,glutenin and gliadin after freezing treatment.The results showed that KGM increased the water holding capacity of gluten and gliadin.The water-holding capacity of frozen gluten in the treatment group increased by 96%,115%,174%,197% and271%,respectively.The water holding capacity of the frozen gliadin increased by83.33%,608.33%,680.56%,966.67% and 1278.00%,respectively.The water holding capacity of frozen glutenin increased first and then decreased.When the KGM substitution rate was 0.5%,the water holding capacity of frozen glutenin increased by20.87%.As the KGM substitution rate continued to increase,the water holding capacity of frozen glutenin decreased.The thermal characteristics showed that the Tp of the gluten and gliadin in the treated group increased,while the glutenin Tp decreased.KGM increased the ordered structure of gluten and gliadin,while the ordered structure of glutenin decreases.Rheological properties showed that KGM increases the viscoelastic properties of gluten,glutenin and gliadin.3.To investigate the effects of konjac glucomannan(KGM)on the foam properties of the frozen gliadin,and the solubility,foaming characteristics,rheological properties,secondary structure,and surface hydrophobicit were used to characterize them.The results showed that the addition of KGM increased the foam volume,foam stability,foam density,protein concentration and gliadin content of the cold gliadin foam.The Fourier transform infrared results showed that in the presence of KGM,the β-turn structure transformed into a stable α-helix structure,while the stable β-sheet structure transformed into a random coil structure.The results of fluorescence spectroscopy showed that when the KGM substitution rate was 2.5%,the hydrophobicity of the gliadin surface increased by 30.90%,but with the KGM substitution rate continued to increase,the gliadin hydrophobicity decreased,and when the KGM substitution rate increased to 4.5%,the hydrophobicity of the gliadin was reduced by 5.76%.4.KGM has a significant improvement on the quality of frozen steamed bread.KGM increased the height of steamed bread,while the volume and specific volume of steamed bread both increased first and then decreased.KGM increased the tightly bound water content of the frozen steamed bread,which can improve the color difference and delay the quality of the steamed bread.