Study On The Synergistic Improvement Of Pentosanase And Glucose Oxidase On The Processing Quality Of Whole Germinated Wheat Flour

Germinated wheat refers to the grain whose length of seed coat is not longer than that of the seed coat when the malt or the young root breaks through the seed coat.After germination of wheat under controlled conditions,polyphenols,y-aminobutyric acid and other functional ingredients can be enriched.The nutritional quality and health benefits of whole wheat flour produced after germination(also known as whole germinated wheat flour)are higher than common wheat flour.However,the activated hydrolase in germinated wheat promotes the hydrolysis of key components,and thus leading to the deteriorated processing quality.The edible quality of Chinese steamed bread(CSB)made from whole germinated wheat flour is undesirable and difficult to attract consumers.At present,domestic researchers rarely focus on germinated wheat flour.If the processing quality of germinated wheat flour can be effectively enhanced,the market of germinated wheat flour will be enlarged,and the dietary nutrition level of residents will also be improved.Against this background,the effects of pentosanase(Pn)and glucose oxidase(Gox)on the key components-arabinoxlyan(AX),protein and AX-protein complexs during the processing of CSB were studied.In addition,their effects on the composition and properties of dough liquor were studied to elucidate the synergism improving mechanism.The main results are as follows:(1)Pentosanase and glucose oxidase could significantly improve the quality of CSB,in which the specific volume increased by 20.33%and the hardness decreased by 36.13%.The content of AX changed between 5%and 9%upontreatmentof different enzymes.Pn and Pn+Gox could significantly increase the water-extracted arabinoxylan(WEAX)content during the processing of CSB.The composition of the water-soluble monosaccharides in the dough revealed that the glucose content in the CSB significantly increased.Meanwhile,the content of xylose and arabinose under Pn treatment increased due to the solubilized effect of Pn on water-insoluble arabinoxylan.The characteristic analysis of WEAX in different extracted samples showed that Pn and Pn+Gox treatment could apparently reduce the molecular weight of WEAX in CSB.FA content in WEAX remarkably increased during processing,and FA content of WEAX in CSB treated with these two enzymes was about twice that of the control group.The oxidation of WEAX by Gox promoted the increase of consistency index of WEAX in CSB.(2)Gox significantly increased the maximum tensile strength and stretching ratio of dough.The water absorption of whole germinated wheat flour wasnot affected by Gox,while it was reduced by addition of Pn,with and the more obviouseffect of Pn+Gox.The results of laser confocal electron microscopy showed that Pn promoted the hydrolysis of AX and enhanced the continuity of the gluten network,while Gox led to the denser gluten network.The addition of enzymes decreased the ability of gliadin to participate in the aggregation of gluten network,but the degree of glutenin increased.The contribution of ionic bonding,hydrogen bonding,and hydrophobicity to maintenance protein structure in CSB was minor.The dough with Pn after mixing was more sensitive to NaCl and low concentration urea.The results of non-reducing electrophoresis showed that double enzymes promote the increase of protein above 26kDa.The results of reducing electrophoresis showed that the glutenin marcopolymers still existed in CSB even under the reducing condition.Pn+Gox improved the binding ability of large molecule AX to proteins.(3)The yield of the aqueous phase of dough containing Pn increased by nearly two times compared withcontrol.Pn effectively increased the AX content in the aqueous phase,and the protein content in the aqueous phase of Gox increased significantly,but the protein content of the Pn+Gox treatment decreased.Gox promoted the conversion of sulfhydryl groups into disulfide bonds in the aqueous phase,and the Gox had a greater molecular weight band(above 180kDa)in the reducing electrophoresis.Gox and Pn+Gox promoted the formation of AX and protein polymers,and significantly improved the thermal stability of aqueous foam,which could contribute to forming more uniform and delicate gas cells in CSB,so as to improve the processing quality of whole germinated wheat flour.