Research On Characteristics And Application Of Wheat Bran

Wheat bran is the by-product of wheat flour processing,with annual output more than 30 million tons.However,because of its bitterness and rough taste,its utilization in food industry is extremely low.In this paper,effects of particle size on chemical properties and antioxidant activity of wheat bran were studied to provide a theoretical basis for suitable selectionsize of wheat bran in food industry.Mixture of wheat bran,soybean and peanuts was fermented by rice leaven and yeast to make fermented bran mixture,then the fermentation was added to wheat flour to prepare fermented wheat bran bread,so as to provide a new way to utilize wheat branand improve the utilization rate of wheat bran.Physical and chemical property study on different size ofwheat bran found that their physical and chemical properties had significant differences(p< 0.05).The expansiveforce and retention ability decreased obviously withwheat bran particle size decreased.But the cation exchange capacity of 30 meshes and 80 meshes wheat bran were allsignificantly lower than that of 120 meshes and 200 meshes.The 120 meshes wheat bran could be used some productsbecause ofits strong cation exchange capacity,higher expansibility(2.03 ml/g),watercapacity(1.60 g/g),and viscosity(2.22 mPa/s).Analysis of wheat bran flavor components found that the main flavor substanceshad no significant differences,andamong different particle size of wheat bran all hadaldehydes(hexanal)and ketones(acetone).In conclusion,particle size had a significant influence on the physical and chemical properties of wheat bran,but had no effect on bran flavor substances.Free polyphenols and bound polyphenol in wheat bran were extracted with different organic solvents,and polyphenol content and the DPPH · scavenging ability was used as the index.The best solvents for free polyphenol and bound polyphenol extration were 80% acetone and ethyl acetate,respectively.The particle size had a significant effect on the content of polyphenols and flavonoids.The wheat bran particle sizesmaller,the lower of bound polyphenoland flavonoid contents,but thehigher of freepolyphenol and flavonoid contents.Both bound polyphenol and flavonoid contents were higher than the free polyphenol and flavonoid contents.The antioxidant activity of wheat bran was positively related to its polyphenol content.Ferulic acid was not detected in free polyphenol of bran,while highcontent of ferulic acid was detected in bound polyphenol,whichwas significantly droppedwith thedecrease size of wheat bran(from 142.17 mg / 100 g to 5.5 0 mg / 100 g)(p< 0.05).In conclusion,particle size of wheat bran hadremarkable influences on its phenol level and antioxidant activity.Mixture of wheat bran,soybean and peanuts was fermented by yeast and rice leaven to improve the edible quality of wheat bran.The optimal fermentation process of wheat bran mixture was obtained by response surface optimization as follows: mixture of 100 g wheat bran,1 g soybean,3 g peanut and 25 ml water was heated to 110 ? for 30 min,after cooling,0.3% rice leaven and 0.3% yeast were added and fermented at 25 ? for 60 h.After fermentation,the bran mixturehad a special ester flavor instead of bitterness,with colour from gray to golden,taste more smooth,so sensory properties of fermentation bran mixture improved obviously compared with those of wheat bran.The contents of free polyphenols and free flavonoids in fermented bran mixture were increased from 1.237 mg/g to2.947mg/g and from 1.637 mg/g to 2.5330mg/g,respectively,and antioxidant activity significantly enhanced(p <0.05).Therefore,the fermentation couldnot only improve the edible quality of wheat bran,but also improve its nutritional value.Appropriate amount of fermented bran mixture was added to wheat flour to make fermented wheat bran breadfor improving bran bread quality and increasing the utilization of wheat bran.All sensory indexes of fermented wheat bran bread were significantly better than that of wheat bran bread(p< 0.01).The sensory score,hardness and color L * and b * values of fermented bran mixture breadhad no significant differences compared with common bread(p>0.05).Compared with ordinary bread and wheat bran bread,the type and content of flavor substancesin fermented wheat bran bread were higher,among which the alcohols and esters are the most obvious,and the increase of these substances contributes to the formation of the unique flavor of bread.The antioxidant activity and antioxidants of fermented wheat bran bread were very high.TheDPPH · scavenging ability,ABTS~+ scavenging ability and total reducing power were 64.9mg/100 g,66.6mg/100 g and 29.4 mg/100 g,respectively.The contents of polyphenols and flavonoids were about 61.4mg/100 g and 98.7 mg/100 g,respectively.The results showed that the addition of wheat bran mixture could improve the quality of wheat bran bread and improve the antioxidant activity of bread.