Study Of Wheat Bran Addition On The Properties Of Dough And You-tiao, Chinese Fried Dough Sticks

The demand of fibre-enriched food has been increased in recent years, because thedietary fibre exerts positive effects on human health such as the hindrance of obesity and themoderation of intestinal flora. Wheat bran is a natural source of fibre, containing lots ofvitamins (vitamin B and vitamin E-based) and minerals, and commonly used to developcereal products. This paper applied wheat bran to traditional Chinese fried dough sticks-You-tiao, to study the effects of bran on the properties of wheat flour and You-tiao, includingmixing properties, water holding capacity, pasting properties and rheological properties ofwheat flour; to study the impact on the moisture in the dough and secondary structure of thegluten protein and on the quality of You-tiao’s texture, specific volume, color, sensorycharacteristics, antioxidant capability and flavor profile. This paper was aimed at applying toindustry of whole wheat flour for making You-tiao.Firstly, this paper studied the effects of bran particle size on processing characteristics offlour and dough. With wheat bran particle size increasing, the water absorption of blendedflour decreased from62.9%to62.0%, the developing time and stability of dough increased by1.5times and1/4times. This showed that the smallest particle size of wheat bran couldcombine more water molecules, but the largest particle size of wheat bran could be moretolerant for mechanical mixing. Fourier transform infrared spectra analysis verified themoisture change in the gluten network as wheat bran was added to the flour, which may bedue to conformation change in the gluten network and water re-distribution atfer wheat branwas added. Extensibility of the dough decreased with the addition of wheat bran, but theeffect of bran particle size was not significant. Pasting properties showed that decreasingparticle size of wheat bran resulted in the decreasing of peak viscosity from2955cP to2847cP and the increasing of pasting temperature from84。.95。C to85.83C.Secondly, in order to standardize the You-tiao’s quality evaluation, a piece ofself-designed mold for making You-tiao dough was conducted. The mass and the specificvolume of You-tiao were controlled at42.1士2.8g and2.8士0.2mL/g, respectively. Thus, thismold could effectively determine the quality of You-tiao. Using the mold, the paper alsostudied the impact of formulation and process parameters on the quality of the dough, and theoptimal terms was determined:3%leavening agent,1.2%salt,60%water addition, moldheight at8mm, frying time of2.5min and frying temperature at175"C.Finally, we studied the effects of bran particle size on the quality of You-tiao, includingsurface hardness, color, specific volume, sensory evaluation, antioxidant capability and flavorprofile. With the addition of wheat bran, surface hardness of You-tiao increased, color wasdarker, but no significant change was found in specific volume. In sensory evaluation, You-tiao with largest particle size of wheat bran obtained higher scores of overallacceptability than that with smaller particle size. And You-tiao containing coarse bran withoutgrinding got the highest scores in every item in the sensory evaluation. In the antioxidantcapability assessment, the DPPH radical scavenging ability of You-tiao with added wheat branwas higher than the controlled sample. The DPPH radical scavenging ability showed apositive relationship with the decreasing bran particle size. Thus, wheat bran could used as apotential antioxidant for industrial production and be applied in the fried foods during fryingand storage. The research found39and41aroma compounds presented in the crumb andcrust of You-tiao, respectively. The flavor profile of crumb was mainly aldehydes, alcoholsand esters while the flavor of crust ketones, pyrazines and benzene. We concluded that flavorcompounds in the You-tiao were (E,E)-2,4-decadienal,3-methylbutanal, l-octen-3-ol, furfuraland furfuryl alcohol. The added bran increased the existence of3-methyl butanal, pentanal,hexanal,1-octen-alcohol, enriching the flavor profile of You-tiao.