Effect Of Pectin With Different Esterification Degree On The Quality Of Steamed Bread Made From Frozen Dough

Frozen dough technology completes the fermentation or partial shaping process before the frozen storage process.This technology can not only help reduce operating costs,but also meet consumers'demand for fresh pasta products.At the same time,because domestic frozen dough technology is still in its infancy,how to control the quality of frozen dough during the freezing process has become the key.This study compared the effects of three freezing temperatures on the quality of frozen steamed breads,and provided a reference for the selection of the freezing temperature of frozen dough in the future.Then the effects of different esterification degrees of pectin on the quality of wheat flour were studied,and on this basis,the effects of different esterification degrees of pectin on the quality of frozen dough and steamed bread were studied,aiming to provide a reference for improving the quality of frozen dough.In this experiment,the specific volume,tissue structure,texture characteristics and the sensory qualities of steamed breads produced at three freezing temperatures(-38�C quick freezing and then-18�C storage,-38�C quick freezing and storage,-18�C quick freezing and storage)were first compared.In general,steamed bread made from dough stored at temperature 1(-38�C quick-freezing and then-18�C)and temperature 2(-38�C quick-freezing plus storage)had a larger specific volume,a soft tissue structure,a smaller hardness,a larger elasticity,and better sensory scores,both of which had better quality than steamed breads made from dough at a temperature of 3(quick-freezing and storage at-18�C),indicating that the lower the freezing temperature,the better the quality of steamed breads made from frozen dough.Considering the cost of freezing,and there was not much difference in the quality of steamed bread between temperature 1 and temperature 2,so temperature 1 was more suitable.Based on the determination of the freezing temperature,the effect of pectin with different esterification degrees on the quality of wheat flour and dough was explored.The results of the Rapid Viscosity Tester(RVA)showed that the peak viscosity,valley viscosity and final viscosity of wheat flour were significantly increased by adding pectin,and the disintegration value became slightly larger.Both the pectin concentration and the degree of esterification had no significant effect on the retrogradation value of starch.The results of the silty test showed that the addition of pectin increased the water absorption of wheat flour,reduced the dough formation time,and increased the dough stability time.As the degree of esterification decreased,the water absorption and dough stability time of wheat flour showed an upward trend.The tensile test results showed that the addition of pectin can increase the stretching resistance,stretching ratio and stretching curve area of the dough,and the lower the degree of pectin esterification was,the enhancement effect on the stretching resistance,stretching ratio and stretching curve area was stronger.The results of fermentation rheological experiments showed that as the concentration of pectin increases,the fermentation height of the dough showed a trend of first rising and then falling.When the pectin concentration is about 1%,it reached the maximum value,and both the air holding volume and the gas volume of the dough showed an upward trend.20%and 40%esterification degree pectin had better effect on dough gas production ability than 60%,80%esterification degree pectin.The results of dynamic rheological experiments showed that adding pectin would increase the storage modulus and loss modulus of the dough,and reduce the loss tangent of the dough.As the degree of esterification of pectin decreased,the storage modulus and loss modulus of the dough showed an upward trend,loss tangent showed a downtrend.Based on the optimum amount of pectin,the effect of pectin with different esterification degrees on the quality of frozen dough and steamed bread was further explored.The changes in the rheological properties,moisture distribution,specific volume,tissue structure,hardness,and sensory quality of the frozen dough in different freezing storage cycles were explored.The experimental resulted show that with the extension of the frozen storage period,the loss tangent of the frozen dough increased,the free water content increased,the specific volume of the prepared steamed bread decreased,the number of internal pores decreased,the hardness increased,and the sensory score decreased,which showed that frozen storage had a negative impact on the quality of frozen dough and steamed bread.After adding 4 kinds of pectins with different esterification degrees,the quality of frozen dough and steamed bread was improved.The specific performance was:after adding pectin,the loss tangent value of the sample dough decreased,and the lower the degree of esterification was,the smaller the value was;the addition of pectin reduced the content of T₂₁ and T₂₃;an appropriate amount of pectin could improve the specific volume of steamed bread,and low esterification degree pectin had a better effect on improving the specific volume of steamed bread;pectin could reduce the number of pores in the steamed bread,and the structure could become compact;pectin could increase the hardness of the steamed bread and the hardness of steamed bread was positively correlated with the degree of esterification of pectin;low-ester pectin could effectively improve the sensory score of steamed bread,and the addition of high-ester pectin could slightly reduce the sensory score of steamed bread.