Production Of Steamed Bread With Sweet Potato Whole Flour With High Additive Content

The sweet potato whole powder as the raw material was mixed with wheat flour to prepare the staple food steamed bread.The effects of the sweet potato powder addition on the dough characteristics were investigated by using the farinograph,extensograph,rheometer,rheofermentometer and texture analyzer,and the quality indicators were measured in steamed bread processing.Considered the dough properties indicators and steamed bread qualities indicators,by adding gluten powder,sodium alginate and sodium carboxymethyl cellulose,the quality of steamed bread with 50%addition of sweet potato whole powder was improved.response surface experiment was carried out on the basis of single factor experiment to optimize the additive formulation in order to develop the sweet potato steamed bread.The main research contents and results are as follows:1. The wheat flour was substituted by sweet potato whole powder at different levels?0%,10%,20%,30%,40%and 50%?and farinograph and extensional properties gelatinization properties,fermentation rheological properties,dynamic rheological properties and microstructure of dough were analyzed.The results showed that the formation time,stability time,and the silty index of the dough significantly decreased and the weakening degree and water absorption rate significantly increased with the increase of sweet potato whole powder addition.Compared with the control group,the formation time and stabilization time decreased by 28.6%and 50.6%,respectively,the weakening degree and water absorption increased by 34.8%and16.5%,respectively,and the silty index decreased by 47.6%.The addition of the sweet potato whole powder gradually reduced the elongation of the dough,the tensile resistance was 50 mm,the maximum tensile resistance and the area of the tensile curve decreased gradually,and the stretching ratio of the dough were continuously increased.With the addition of sweet potato whole powder,the peak viscosity of the mixed powder decreased from 1543.33 m Pa.S to 899.00 m Pa.S,the falling value decreased from 766.08 m Pa.S to 241.81 m Pa.S,and the rebound value decreased from661.67 m Pa.S to 195.00 m Pa.S,and compared with the control group,the peak viscosity,the falling value and the rebound value decreased by 41.9%,68.4%and70.5%,respectively.The gelatinization characteristic curve of the dough significantly decreased with addition of the sweet potato whole powder.The maximum expansion height of the dough was significantly reduced,especially dough with the 50%sweet potato whole powder was reduced by 68.9%compared with the control group,the dough holding rate was significantly reduced,the maximum gas release curve height and the total CO₂ gas production volume were gradually increased,increased by 54.0%and 41.5%,respectively.The apparent viscosity of the dough samples gradually decreased as the shear rate increased,exhibiting the characteristics of the pseudoplastic fluid,but the addition of sweet potato whole powder increased the apparent viscosity of the dough.The addition of sweet potato whole powder increased the elastic modulus?G'?and viscous modulus?G"?of the dough and the tangent value tan?decreased gradually.The G'of the dough was larger than G",showing typical weak gel dynamic rheological properties.The maximum creep compliance of the dough was significantly reduced with the addition of the sweet potato whole powder,leading to the adverse effects of the hardness of the steamed bread.It can be observed by microstructure of the dough that the discontinuous gluten network increased and obvious cracks appear in the dough with addition the sweet potato powder.The gluten protein network structure was became sparse and dispersed,and the starch granules gradually cannot be wrapped,showing a leak state of dough.And in the case of loose distribution,the number of exposed starch granules increases.2. The wheat flour was substituted by sweet potato whole powder at different levels?0%,10%,20%,30%,40%and 50%?and the effects of sweet potato powder on the sensory score,color difference,and texture characteristics of steamed bread were investigated.The results indicated that the specific volume of steamed bread decreased from 2.61 m L/g to 1.70 m L/g with the addition of the sweet potato whole powder.Compared with the control group,the specific volume and sensory score of steamed bread with 50%sweet potato powder decreased by 34.9%and 32.6%,respectively.The hardness,adhesiveness and chewiness of the steamed bread were gradually increased,and the elasticity,cohesiveness and recovery were gradually decreased.Compared with the control group,the quality indicators of steamed bread with the addition of the 30%-50%sweet potato powder significantly decreased.According to the analysis of the dough characteristics,when the sweet potato whole powder addition was less than 30%,the processing characteristics of the mixed dough and the quality of the steamed bread were within an acceptable range.3. In order to develop high addition quantity sweet potato whole powder steamed bread,the addition levels of gluten powder,sodium alginate,and sodium carboxymethyl cellulose were used as experimental factors.Based on the single factor test,the specific volume,sensory score,color difference,and texture characteristics of the steamed bread were used as indicators.According to the three-factor and five-level quadratic orthogonal rotation combination test,the optimal improver formula for 50%addition of sweet potato whole powder steamed bread was:6.0%of gluten meal,0.3%sodium alginate,and 0.2%sodium carboxymethyl cellulose.Under these conditions,the specific volume of the steamed bread was 2.54 m L/g,the sensory score was 92.25,the color difference was 79.21,and the hardness was 5478 g.