Biological Modification Of Wheat Bran And Its Application In Whole Wheat Steamed Bread

Wheat bran(WB),one of the main by-products of wheat processing,is mostly used in the feed and brewing industry,which is rich in dietary fiber and the sources of high-quality plant protein.In addition,it also contains a variety of active substances such as alkylresorcinols,flavonoids and phenolic acids,which have antioxidant,anti-aging,anticancer,anti-inflammatory and other physiological functions and can effectively prevent and treat obesity,diabetes,cancer and other diseases.China is a big wheat producer,and the bran has abundant sources,but it is seldom used in food because of its bitter and rough taste,which Reduced the edible quality of flour.Wheat bran is abundant,especially in China.However,it is seldom used in food because of its bitter and rough taste,which results in the waste of high-quality resources.At present,physics,chemistry and biology are three common ways to modify wheat bran.Biological methods can be divided into fermentation and enzymatic hydrolysis,which have become the focus of improving the quality of wheat bran in recent years because of mild operating conditions,high efficiency,green pollution-free and so on.Lactobacillus,as a common probiotics,has been proved by more and more studies to be effective in improving the quality of wheat bran.Enzymatic hydrolysis requires only a small amount of addition to improve the quality of wheat bran under mild conditions.Therefore,it is of great significance to study the effect of lactic acid bacteria and enzyme preparation on improving the quality of wheat bran,to increase the utilization rate of wheat bran and to increase its economic added value.In this paper,a strain of Enterococcus faecalis M2,which could improve the antioxidant properties of wheat bran,was screened out by solid state fermentation,the fermentation conditions were optimized,then to explore the improvement effect of wheat bran.In addition,the effects of cellulase,xylanase,pectinase and ?-glucanase were screened by single factor test,and the formula and action conditions of compound enzyme preparation were determined by orthogonal test,and then to investigate the improvement effect of compound enzyme preparation on wheat bran quality.On this basis,biological enzyme was coupled with solid fermentation to investigate the modification effect and the effect of different biological modification of wheat bran on the quality of whole wheat dough and steamed bread.providing a basis for improving the quality of whole wheat products.The main research in this paper is as follows:1.The study of screening a dominant lactic acid bacteria by solid-state fermentation with wheat bran and optimiziation of fermentation conditions.By solidstate fermentation with wheat bran,lactobacillus isolated from pickles,pickles and sour milk preserved in our laboratory was used to select a dominant strain of Enterococcus faecalis M2.which could significantly improve the antioxidant capacity of wheat bran.The optimized conditions were further obtained by single factor,PB and BBD tests.The results showed that when the mean grain size of wheat bran was 320 nm,the water-to-material ratio was 1.8:1,the inoculation amount was 10%,the fermentation time was 39 h,and the fermentation temperature was 37?,the TAOC of wheat bran was reaching 7.396 ?mol/g.The cell wall structure and protein of fermented wheat bran were hydrolyzed significantly,while the content of soluble dietary fiber and total free amino acid was significantly increased to 4.10 g/100g and 3786 mg/Kg,respectively.Compared with raw wheat bran,alkyl resorcinol,total phenol and flavonoids increased by 45.45%,39.09%and 26.39%,respectively.After solid state fermentation,the content of 8 phenolic acids in wheat bran increased to different degrees,of which ferulic acid increased by 1.60 times to 22.51 g/g.The total antioxidant capacity and free radical clearance rate of wheat bran reached 7.60 ?mol/g and 60.68%respectively,and the antioxidant properties were significantly improved,indicating that Enterococcus faecalis M2 could effectively improve the quality of wheat bran.2.The physicochemical properties and nutritional properties of wheat bran were improved by bioenzymatic method.The formulation of the compound enzyme preparation and the optimal conditions for solid enzymatic hydrolysis were determined by single factor and orthogonal test.The result showed when the addition amount of cellulase,xylanase,pectinase and ?-glucanase were 60 U/g,1 U/g,60 U/g and 450 U/g,respectively,enzymatic hydrolysis was pH6.0,enzymatic hydrolysis temperature was 50?,enzymatic hydrolysis time was 1.5 h,the SDF content of wheat bran was reaching 19.54 g/100g.compared with raw wheat bran,the soluble dietary fiber of wheat bran after enzymatic hydrolysis reached 19.74 g/100g,an increase of 13 times,and the water holding/oil holding and expansion force decreased significantly,respectively,by 24.61%,30.40%and 18.55%.The total antioxidant capacity of wheat bran was up to 5.94 ?mol/g.and the free radical scavenging capacity was up to 48.02%,three times higher.In addition,the content of water-soluble polysaccharides and total reducing sugars reached 205.80 mg/g and 104.33 mg/g,respectively,and the content of alkyl resorcinol,total phenol and flavonoids were more than doubled.The content of 8 phenolic acids in enzymatic hydrolysis of wheat bran also increased to different degrees,among which ferulic acid,gallic acid and p-hydroxybenzoic acid increased most,reaching 16.21,52.39 and 3.96 g/g respectively,indicating that solid complex enzymatic hydrolysis could effectively improve the quality of wheat bran.3.Biological enzymatic coupled solid state fermentation improved the quality of wheat bran.The physicochemical properties and nutritional properties of wheat bran treated by enzymatic coupled solid state fermentation were further improved.Compared with the control group,the soluble dietary fiber of wheat bran after fermentation,enzymatic hydrolysis and coupling treatment was significantly improved,reaching 9.83 g,19.47 g and 18.44 g/100g,respectively.The total antioxidant capacity and free radical clearance rate increased by 213%and 39.56%,respectively,to 8.41 ?mol/L and 66.25%.Compared with the wheat bran treated alone,the cell wall and protein hydrolysis of the wheat bran after the coupling treatment were more damaged,and the growth rates of total phenol,alkyl phrycatechol and flavonoids were also greater,reaching 2.97,1.92 mg/g and 401.03 g/g,respectively.In addition,the increase amplitude of 8 phenolic acids was also improved,especially ferulic acid,reaching 43.90 g/g,indicating that the bio-enzymatic coupled solid state fermentation technology is a more effective method to improve the quality of wheat bran4.Study on effects of different biomodified wheat bran on the quality of whole wheat dough and steamed bread.Wheat bran processed by solid-state fermentation,solidstate enzymatic hydrolysis,bio-enzymatic coupled solid state fermentation technology was added to wheat flour in the original proportion to further prepare the corresponding wholewheat dough and steamed bread,to investigate the effects of different biomodified wheat bran on the quality of whole wheat dough and steamed bread.The results showed that compared with the control group and the single treatment group,the fermentation activity,dynamic rheological properties of the whole wheat dough prepared by the coupled treatment group and the profile structure,texture analysis,sensory evaluation and specific volume of whole wheat steamed bread were better,which were the closest to blank control group.The biomodified wheat bran can also increase the variety of flavor and balance the flavor of whole wheat steamed bread.Compared with the whole wheat dough,the antioxidant properties of steamed steamed buns and the content of alkyl phrylenol,total phenol and flavonoids remained stable.Biomodified wheat bran can improve the edible quality and nutritional quality of whole wheat steamed bread,especially the biological enzymatic coupled solid state fermentation technology,which showed that there is a synergistic effect between them.