Effects Of Debranning And Ultra-ifne Grinding On The Quality Of Wheat Flour And Cookies From Blue And Purple Wheats

In order to improve the exploitation value and processing quality of blue and purplewheats, in the present study, the blue and purple wheats were used to prepare flour bydebranning. Flour quality affected by the debranning of blue and purple wheats was studied.Then the blue and purple wheat flours were made into different types of crackers based ontheir processing characteristics, and the effects of different bran addition by ultra-finegrinding on their processing properties was studied. Meanwhile, select the debranning levelsof0%,4%and8%, the kernels were grinded into whole wheat flour by different grindingprocesses. The effects of debranning and ultra-fine grinding on flour and cookies qualities ofwhole wheat flour from blue and purple wheats were investigated. It will provide sometheoretical basis and new processing methods for the popularity application of blue and purplewheats. The main results were as follows:1. Different debranning levels had effects on flour yield, heavy metals residual, ash andprotein content of blue and purple wheat flour. Debranning also had positive effects on gluten,color, pasting and rheological properties of flour. The results showed the most desirabledebranning level of blue wheat flour was3.84%-5.57%, and purple wheat flour was4.54%-6.25%.2. Different bran addition by ultra-fine grinding had significantly affected the processingproperties of crackers made from blue and purple wheat flours. The results showed that thecrackers added10%bran by ultra-fine grinding had increased the greatest degree of mineralelement content, while meeting the people’s sensory requirements of crackers made from blueand purple wheat flours.3. Debranning and ultra-fine grinding had significantly affected the quality of wholewheat flour from blue and purple wheats. Debranning had positive effects on gluten, color,pasting and rheological properties of whole wheat flour. After ultra-fine grinding of wholekernels, the mean particle diameter of whole bule wheat flours distributed from21.33μm to20.22μm with the increase of debranning level. The values of whole purple wheat flour werefrom21.32μm to24.77μm. With regard to grinding process, the protein and ash contents ofblue and purple wheats were not significantly reduced in the ultra-fine grinding process.However, the whole wheat flour contained more ultra-fine particles showed the higher wetgluten content, gluten index, paste viscosities and rheological parameters, were compared tothose of hammer milling samples.4. Debranning and ultra-fine grinding had significantly affected the processing quality of whole wheat cookies from blue and purple wheats. Debranning significantly improved theprocessing quality of whole wheat cookies by lowered hardness of cookie dough and cookiesbreak strength. Moreover, the cookies of debranning level of8%were better than those ofdebranning level of4%. More ultra-fine grinding composition in whole wheat flour couldimprove the textural properties of cookie dough such as springiness, cohesiveness andchewiness, while the cookies were not easily dispersed in baking.5. Debranning and ultra-fine grinding had significantly affected the antioxidant ability ofwhole wheat flour and cookies from blue and purple wheats. TPC, TFC andDPPH·scavenging ability of blue wheat were higher than those of purple wheat. It alsoshown that baking resulted the loss in TPC and TFC, but increased the value ofDPPH·scavenging ability. The antioxidant ability of whole wheat flour and cookies werelowered with the increase of debranning level. Moreover, ultra-fine grinding had enhanced theantioxidant ability of whole wheat flour and cookies from blue and purple wheats. The wholewheat flours and cookies by kernel ultra-fine grinding had highest TPC, TFC andDPPH·scavenging rate. The TPC of whole blue and purple wheat flours by kernel ultra-finegrinding increased by0.5mg GAE/g and0.3mg GAE/g, TFC of those increased by0.6mgRE/g and0.3mg RE/g, DPPH·scavenging rate of those increased by4%and5.5%, werecompared to those of hammer milling samples.