Quality Improvement Of Steamed Bread With High-Bran Content

Epidemiological studies have shown that whole grain foods contribute to the resistance against chronic metabolic diseases such as obesity,diabetes,cardiovascular disease and cancer,but there is a lack of systematic research and product development on whole grains in China.Steamed bread,as a staple food in north China,accounts for more than 30% of the total flour-based food consumption.The content of vitamins,minerals,dietary fiber and active substances in high-bran content steamed bread was higher than that in fine white steamed bread.However,it is difficult to be accepted by Chinese residents because of its poor,rough taste and hard texture.In this study,Jimai 17 was used as experimental material to produce steamed bread with high-bran content by using the traditional dough starter(Jiaozi)from Yuncheng,Shanxi province.On this basis,the quality of high-bran content steamed bread was improved by using carrageenan(CGN),locust bean gum(LBG),wheat gluten and sodium stearoyl lactate(SSL),and the effects of compound modifiers on the rheological properties of high-bran content dough were studied.The purpose of this study is to provide a theoretical basis for improving the quality of high-bran content steamed bread.The specific research contents and experimental results are as follows:Firstly,the addition of CGN and LBG increased the water absorption of wheat flour;it increased the formation time and stability time of high-bran content dough;it improved the tensile properties;it strengthened the gluten network;it boosted the dough stability and toughness.The peak viscosity,minimum viscosity and final viscosity of wheat flour were improved.The improvement in LBG is more significant.With the addition of wheat gluten,the formation time and stability time of dough increased at first and then decreased.The weakening degree of dough decreased at first and then increased.The stability of dough was better when the addition amount was 2.0%.The peak viscosity,the minimum viscosity,the final viscosity,the attenuation value and the retrogradation value of wheat flour were all decreased,which improved the gelatinization stability of wheat flour and inhibited the short-term retrogradation of wheat starch.The extensibility of high-bran content dough increased with the addition of SSL,which increased the stability of gluten protein.The addition of SSL significantly increased the peak viscosity and decreased the retrogradation value of the flour,which played a significant role in anti-aging.Secondly,the effects of CGN,LBG,gluten and SSL on the quality of high-bran content steamed bread were studied.The results showed that with the addition of CGN,the specific volume and height-diameter ratio of high-bran content steamed bread increased at first and then decreased.When the content of CGN was 1.5%,the specific volume and height-diameter ratio of high-bran content steamed bread reached the maximum of 1.97 m L/g and 0.70,the hardness and elasticity of steamed bread were the lowest,and the sensory score was the highest(82.2).Compared with CGN,LBG improves the quality of steamed bread more significantly.When LBG is added at 2.0%,the specific volume and height-to-diameter ratio of high-bran content steamed bread reach the maximum,which are 2.10 m L/g and 0.74.And the recovery value was increased,the elasticity,chewiness and stickiness were better,the sensory score was higher,at 83.8.The addition of wheat gluten decreased the hardness of high-bran content steamed bread,and the elasticity,resilience and stickiness increased significantly.When the addition amount was 2.0%,the sensory score was 84.7.With the addition of SSL,the cohesion of high-bran content steamed bread increased.Finally,the results of the orthogonal test showed that the high-bran content steamed bread had the highest sensory score and better quality when LBG was 2.0%,gluten was1.75% and soybean protein was 0.45%.The effect of compound improver on the properties of whole wheat dough was studied.According to the rheological properties,the elastic modulus and the viscosity modulus of the dough were increased by the compound additives,and the viscoelasticity of the dough was increased remarkably.The results of SEM showed that the high gluten dough had a more compact gluten network structure,which prevented the gluten network from hollowing and breaking,and made the distribution of the protein matrix more uniform.