Studies On The Rheofermentation Properties And Baking Performance Of High Antioxidative Buckwheat Dough And Bread

This research mainly focused on the influence of different fermentation and bakingconditions on rutin content, quercetin content and antioxidant properties of buckwheat bread,gum arabic (AG), guar gum (GG) and carboxymethylcellulose sodium (CMC) on dynamicrheological properties, rheofermented rheological properties of buckwheat dough, bakingproperties of buckwheat bread and staling characteristics of bread during storage. Theimprovement effect of α-amylase, transglutaminase and pentosanase on buckwheat breadcontaining hydrocolloids was also investigated.High performance liquid chromatography (HPLC) was utilized to study the rutin andquercetin content of wheat flour, buckwheat flour and buckwheat bread. Antioxidant capacityof different breads was analyzed under different baking conditions through studying the totalphenol content and clear capability of DPPH radical and ABTS radical, and with studyingbaking properties to choose a suitable processing method, then introduce hydrocolloids toimprove the quality of buckwheat bread under selected condition. Long time of fermentationwas detrimental for the rentention of oxidation substance while the low temperature was agood factor. Together with antioxidant capacity and bread quality analysis, a good processingcondition was established: fermented for1.5h, baking temperature of upper fire170°C,under fire210°C, time for22minutes.The effects of different hydrocolloids on the thermomechanical, rheofermented anddynamic rheological properties, microstructure of doughs and bread baking properties andaging effect of storage breads were investigated by using Mixolab, F3rheofermentometer,dynamic rheometer, scanning electron microscope (SEM), Texture analyzer (TA) anddifferential scanning calorimetry (DSC). The effect of different hydrocolloids on the proteinand starch in buckwheat dough was also detected. Results showed that with addition ofbuckwheat flour the water absorption decreased significantly, which decreased from62.7%to53.0%, and the stability time was significantly reduced, the weakness degree of proteinincreased, the staling of breads was aggravated. The damage brought by buckwheat flour wasinhibited with addition of hydrocolloids, the weakness degree of protein was inhibited, andC5-C4value decreased dramatically. After adding hydrocolloids, tan value decreased, andthe degree of polymerization decreased. The maximum height of dough (Hm), retentioncoefficient of gas release curve (R) and stabilization time (Tx) went up by22.2mm,5.4%and12.5minutes when1.5%CMC was added. The specific volume increased to different extentwith addition of hydrocolloids. When CMC was added at1.5%, the specific volume increasedfrom4.20mL/g to4.78mL/g. Bread hardness decreased to370.538g. The average size ofbread pore (AS), area fraction (AF), cell density (CD) and the internal texture of bread wereimproved. Staling rate was slowed down. The value of overall acceptability increased to7.0.Using response surface method to analyze the effect of different hydrocolloids added tobuckwheat bread together, it was found AG and CMC as well as AG and GG had synergisticeffects, and the combination could contribute to better results than added by one kind only.The addition of hydrocolloids did not influence the retention of antioxidant property. We also used response surface method to introduce three kinds of enzymes to achievebetter improvement for buckwheat bread with hydrocolloid AG and CMC, and found that theoptimum adding amount was19.58mg/kg-amylase,0.27%transglutaminase and23.36mg/kg pentosanase. Under that addition content, the specific volume was5.22mL/g, and thehardness was227g. With the addition of the optimized additives the hardness increase ofbread during storage was slowed more. The improvement of bread quality was better. Theamylopectin retrogadation enthalpy deceased from2.2240J/g to1.8954J/g.The addition ofenzymes did not influence the retention of antioxidant property.