Study On The Improvement And Mechanism Of Processing Quality Of 70% Tartary Buckwheat Noodles

Tartary buckwheat has various physiological effects such as antidiabetic,antihypertension,cholesterol lowering.For China is a major consumer of noodles,Tartary buckwheat noodles are very popular among consumers.In order to endow the Tartary buckwheat noodles with sufficient physiological effects,it is necessary to increase the content of Tartary buckwheat flour in noodles as much as possible.However,Tartary buckwheat flour lacks enough gluten protein,resulting the difficulty to form dough sheets during noodle processing,and the yield of Tartary buckwheat noodles is quite low.Therefore,this paper improved the processing quality of 70%Tartary buckwheat noodles by optimizing the varieties of wheat flour,wheat gluten and pre-gelatinized starch,getting the optimal addition of wheat gluten,pre-gelatinized starch and alkali.What's more,the gluten quality of wheat flours and wheat glutens,the fine structure and physicochemical properties of starch,and the protein properties,microstructure and water distribution of dough sheets were studied,to clarify the effect and mechanism of wheat flours,wheat glutens,pre-gelatinized starch and alkali on the processing quality of the high-added Tartary buckwheat noodles.The main research and results were as follows:?1?Based on the evaluation of the texture properties of dough sheets,the improvement effect of wheat flours and wheat glutens with different gluten quality on the processing quality of high-added Tartary buckwheat noodles was compared.And this study clearly determined the core indicator of wheat flours and wheat glutens for multigrain noodles.Moreover,the mechanism of improving the processing quality of Tartary buckwheat noodles was clarified by confocal laser scanning microscope.The results showed that wheat flour with high gluten index improved the tensile strength of Tartary buckwheat dough sheet,and significantly reduced the adhesiveness of dough sheet.For every 1%increase of wheat gluten addition,the tensile strength of dough sheet increased by 40.29 g,while the adhesiveness increased by 82.25 g·sec.The tensile strength of dough sheets was significantly positively correlated with the gluten index of wheat flour and wheat gluten?r=0.853,p<0.01?,but was not significantly correlated with the protein content or wet gluten content?p>0.05?.The adhesiveness of dough sheets has no correlation with the protein content,wet gluten content and gluten index?p>0.05?.The higher the gluten index,the denser the gluten network of Tartary buckwheat dough sheet and the higher the protein matrix value?PMV?,resulting in the greater tensile strength.Therefore,adding wheat flour?F2?and wheat gluten?G2?with high gluten index,or increasing the wheat gluten addition significantly improved the processing quality of high-added Tartary buckwheat noodles.Gluten index can be used as an indicator to select wheat flour and wheat gluten for multigrain noodles,and wheat flour and wheat gluten with high gluten index improved the processing quality of Tartary buckwheat noodles by forming a denser gluten network.?2?The improvement effect of three kinds of pre-gelatinized starch with different addition on the processing quality of high-added Tartary buckwheat noodles was compared.The relationship between the fine structure and physicochemical properties of starch,and the processing quality of dough sheets were studied.The microstructure and water distribution of dough sheets were analyzed to clarify the improvement mechanism of the processing quality of dough sheets.The results showed that the tensile strength and adhesiveness of dough sheets were significantly positively correlated with pre-gelatinized starch addition.The improvement effect of drum dried tapioca starch?DT?on the tensile strength of dough sheet was significantly higher than that of drum dried maize starch?DM?and extrusion cooked maize starch?EM?.The tensile strength and adhesiveness of dough sheets were positively correlated with the ratio of long amylopectin?DP37-100?,average chain length of the amylopectin,room temperature viscosity and water absorption index?WAI?of pre-gelatinized starch,while were negatively correlated with the amylose content.The PMV was significantly positively correlated with the tensile strength of dough sheets,and the PMV and the deep-bound water content(A₂₁)of DT3?with 9%DT added?were both significantly higher than that of EM3 and DM3,that is,the degree to form gluten network and the strength to bind water of DT3 were stronger than that of the latter.Therefore,pre-gelatinized starch significantly improved the tensile strength of dough sheets,and DT showed the most significant effect.The high proportion of long amylopectin?DP37-100?and average chain length of amylopectin gave the pre-gelatinized starch a high room temperature viscosity and WAI,and the strong viscosity and water absorption promoted the stretching of gluten network and increased the water binding capacity by increasing the adhesion of the components,resulting in the improvement of the tensile strength of dough sheets.?3?Based on the evaluation of the texture properties of dough sheets,the improvement effect of alkali additions on the processing quality of high-added Tartary buckwheat noodles was compared,and the optimal alkali addition was determined combining with the cooking and eating quality of noodles.The wet GMP weight,free thiol?-SH?and disulfide bonds?S-S?content,as well as the microstructure,water distribution of dough sheets were analyzed,to clarify the improvement mechanism of the processing quality and eating quality of Tartary buckwheat noodles.The results showed that the tensile strength and extension distance of dough sheets were both significantly positively correlated with alkali addition?r₁=0.974,p<0.01;r₂=0.921,p<0.05?.When the alkali addition was 0.3%,the tensile strength of dough sheet was higher than 300 g.With the increase of alkali addition,the adhesiveness increased first and then decreased,and it reached the highest value of 276.40 g·sec when the alkali addition was 0.9%,which was far lower than 600 g?sec.Alkali also improved the eating quality of noodles,and the hardness,resilience,elasticity and chewability were significantly increased?p<0.05?.At 0.6%alkali addition,the hardness,elasticity and chewability of Tartary buckwheat noodles reached the highest value.However,the addition of alkali also caused the decrease in cooking quality.The tensile strength and extension distance of dough sheets,and the elasticity of noodles were all significantly positively correlated with the wet GMP weight and S-S content,but they were significantly negatively correlated with the-SH content,the lateral relaxation time of weak-bound water and free water(T₂₂,T₂₃).Therefore,alkali promoted the formation of gluten network in Tartary buckwheat dough sheets,giving the noodles higher processing and eating quality.0.6%was the optimal alkali addition to improve the processing quality of high-added Tartary buckwheat noodles,taking into account the cooking and eating quality.