Preparation And Quality Evaluation Of Tartary Buckwheat Bread With High Resistance Starch

Tartary buckwheat is an excellent medicinal and edible crop,rich in bioactive substances,high quality protein,dietary fiber,and other nutritional and functional components.However,Tartary buckwheat lacks gluten protein and low content of natural resistant starch,which limits its application and development in baked products with low GI value.In this study,the content of resistant starch in Tartary buckwheat was significantly increased by the method of pullulanase combined with multiple moist heat treatment.The modified Tartary buckwheat flour was used as raw material,and the modified gluten was matched with the improved quality gluten.The high resistant starch Tartary buckwheat bread was prepared successfully.The success of this study has important reference value to modified Tartary buckwheat powder in baking products.Two hundred Tartary buckwheat germplasm materials were screened and subjected to Pullulanase(PUL)deramination and repeated humid heat treatment(HMT).The effects of Pullulanase dosage and humid heat treatment times on the content of resistant starch in Tartary buckwheat powder were investigated.The results showed that PUL,HMT and Pul-HMT treatments could increase the content of resistant starch in Tartary buckwheat.The dosage of Pullulanase was 10 U/g,and the best effect was obtained after two treatments with humidity and heat.The resistant starch content increased significantly from 4.74% to 13.38%(p < 0.05).Compared with the unmodified Tartary buckwheat powder,the surface of Pl-10-HMT-2 sample changed from smooth to concave-convex and formed obvious reinforcement structure.X-ray diffraction showed that the starch crystal structure changed from A type to A+V type,and the relative crystallinity decreased significantly from 26.98% to 10.96%(p< 0.05).Infrared spectra showed that the short-range ordered structure of starch was not significantly changed(p > 0.05).The results show that the modified Tartary buckwheat powder produces a more rigid double helix structure,but its thermal stability is reduced.The effects of modified Tartary buckwheat flour supplemental level on texture properties of dough were investigated.The results showed that,with the modified Tartary buckwheat flour supplemental level increasing from 20% to 40%,texture properties of dough were significantly decreased(p < 0.05),and gluten supplementation could significantly improve texture properties of dough(p < 0.05).According to the sensory evaluation and texture parameters,based on the ratio of 35%modified Tartary buckwheat powder to 24% gluten powder,the effects of the addition levels of white granulated sugar,salt,butter and yeast(accounting for the proportion of total flour)on the bread quality were investigated,and the best high-resistant starch formulation of Tartary buckwheat bread was obtained: 41 percent high-gluten wheat flour,35 percent modified Tartary buckwheat flour,24 percent gluten,17 percent sugar,1.2 percent salt,0.5 percent yeast,and 9 percent butter.The final sensory score was 88.2.Sensory evaluation,texture evaluation and nutritional evaluation were conducted on wheat bread(B0),wheat bread without added grain(B0),modified Tartary buckwheat bread(RB)without added gluten,common Tartary buckwheat bread(BB)without added gluten,modified Tartary buckwheat bread with added gluten(RWB),and common Tartary buckwheat bread with added gluten(BWB).The effects of Tartary buckwheat flour modification and gluten addition on bread quality were investigated.The results showed that modified Tartary buckwheat flour could significantly reduce the sensory quality and texture quality of bread,and gluten added significantly improved the sensory score of RWB,which was close to B0 and significantly higher than that of other bread(p < 0.05).Modified Tartary buckwheat powder significantly increased the resistant starch content in bread(p < 0.05),and the increase of resistant starch in RB to BB and RWB to BWB was 120.31% and132.89%,respectively.A variety of phenolic compounds were detected in Tartary buckwheat bread before and after adding modified Tartary buckwheat flour,but only cinnamic acid existed in wheat bread.In addition,modified treatment and gluten could regulate the content of phenolic compounds.The effects of modified Tartary buckwheat bread(RB),common Tartary buckwheat bread(BB),common Tartary buckwheat bread(RWB)and common Tartary buckwheat bread(BWB)with wheat gluten on the quality of bread were evaluated by sensory evaluation,texture evaluation and nutritional evaluation.The results showed that modified Tartary buckwheat flour could significantly reduce the sensory quality and texture quality of bread,and gluten added significantly improved the sensory score of RWB,which was close to B0 and significantly higher than that of other bread(p < 0.05).Modified Tartary buckwheat powder significantly increased the resistant starch content in bread(p < 0.05),and the increase of resistant starch in RB to BB and RWB to BWB was120.31% and 132.89%,respectively.A variety of phenolic compounds were detected in the bread of Tartary buckwheat flour before and after the modification.In addition,the modified treatment and gluten could regulate the content of phenolic compounds.