Study On The Processing Technology And Quality Improvement Of Frozen Dough Steamed Bread Made With Fermented Glutinous Rice

Steamed bread made with fermented glutinous rice are unique fermented food in Jiangsu and Zhejiang provinces.They are very popular because of their sweetness,deliciousness and rich nutrition.The frozen dough also promotes the rapid development of the industry due to its convenience,time-saving and land-saving advantages.The frozen dough steamed bread made with fermented glutinous rice can not only satisfy consumers’pursuit of taste and nutrition,but also meet the development needs of the industry.Therefore,firstly,the effects of different pretreatment processes of fermented glutinous rice on the physical and chemical properties and quality of traditional steamed bread made with fermented glutinous rice were studied in this paper.Then,the quality variation rules of frozen dough steamed bread were studied in the process of frozen storage and make targeted improvements to its quality.Firstly,in this study,the effects of fermented glutinous rice pretreatment（fermented glutinous rice+bran GB;fermented glutinous rice+rice GR;fermented glutinous rice+bran+rice GRB）on the physicochemical properties of fermented glutinous rice and the fermentation performance and quality of steamed bread were studied.The results showed that the pretreatment technology could significantly increase the number of yeast and lactic acid bacteria in fermented glutinous rice（p<0.05）.Among them,the number of yeast and lactic acid bacteria in fermented glutinous rice+bran+rice（GRB）group increased by 13.53%and 13.62%,respectively.The data of fermentation rheometer showed that the gas production capacity and the maximum expansion height of dough were increased in the fermented glutinous rice+rice（GR）group,while the gas holding capacity of dough was increased in the fermented glutinous rice+bran（GB）group.The pretreatment processes significantly increased the specific volume,springiness and resilience of steamed bread（p<0.05）,and decreased the hardness of steamed bread.GRB group had the most significant effect on quality improvement,with the specific volume increased by 47.32%,springiness and resilience increased by 13.09%and 41.93%,respectively.GC-MS and electronic nose were used to analyze the flavor compounds in steamed bread made with fermented glutinous rice.The results showed that the different fermented glutinous rice pretreatments could significantly change the volatile compounds in steamed bread.Compared with blank group（G）,the types of ester in GRB group increased,the aldehydes and ketones in GB group increased,and the olefin in GR group increased.Secondly,the effect of freezing storage process on the quality of frozen dough steamed bread was investigated,and the quality was improved by improvers（sodium alginate,monoglyceride,potassium carbonate）.With the increase of frozen storage time,the specific volume,springiness and resilience of frozen dough steamed bread decreased and the hardness increased.The improvers can improve the specific volume and texture characteristics of frozen dough steamed bread,among which the improvement effect of potassium carbonate is the most significant（p<0.05）.The specific volume of 0.2%potassium carbonate increased by 33.57%,the springiness increased by 11.39%,the resilience increased by 33.33%,and the hardness decreased by 32.43%after frozen storage for 6 weeks.LF-NMR data showed that the T₂₁ value of the dough decreased after the addition of the improver,among which the effects of potassium carbonate and sodium alginate were significant.With the increase of storage time,the content of freezable water in frozen dough steamed bread increased.The improver can significantly reduce the increase of freezable water content.After frozen storage for 6 weeks,the freezable water content of monoglyceride,potassium carbonate and sodium alginate decreased by 11.56%,12.2%and 6.37%,respectively.The rheological results show that after frozen storage for 6weeks,the elastic modulus and viscous modulus of the frozen dough decreased significantly,while the addition of improver can improve the change,and the effect of sodium alginate was the most significant.The microstructure of frozen dough was analyzed by scanning electron microscope.It was found that with the increase of frozen storage time,starch granules were exposed,the pores in gluten structure increased and the structure was destroyed.However,sodium alginate group can significantly improve the effect of frozen storage process on the gluten structure of frozen dough.The changes of protein components in frozen steamed bread were analyzed by SDS-PAGE,and it was found that the color of the high molecular protein bands in the potassium carbonate group became lighter.The analysis of the content of free sulfhydryl group also showed that the content of free sulfhydryl group decreased significantly in the potassium carbonate group,which proved that potassium carbonate could promote the disulfide bond crosslinking of frozen dough steamed bread.Then,the quality change of frozen dough steamed bread during freezing-thaw process and the quality improvement of the steamed bread with improver were further studied.The results showed that the specific volume and height-diameter ratio of steamed bread significantly decreased with the increase of freeze-thaw times（p<0.05）.The improver can improve the specific volume and height-diameter ratio.The sodium alginate group was freeze-thawed for 4times,and the specific volume and height-diameter ratio increased by 7.64%and 39.53%,respectively.The texture experiment also showed that with the increase of freeze-thaw times,the hardness of steamed bread increased,while the springiness and resilience decreased.The improver could significantly reduce the hardness of the frozen dough steamed bread.The effects of sodium alginate and potassium carbonate were the most significant（p<0.05）.LF-NMR data showed that the A₂₃ value of free water increased by 20.14%with the increase of freeze-thaw times.Differential Scanning Calorimeter data showed that the freezing water content of the blank group increased significantly by 36.72%.However,improver can reduce the increase of free water content during freeze-thaw process.The rheological data also showed that after freeze-thaw 4 times,the elastic modulus and viscous modulus of dough decreased significantly,but sodium alginate could significantly increase the elastic modulus and viscous modulus of dough.The scanning electron microscope data showed that after freeze-thaw for 4 times,the deterioration of gluten structure became serious,but potassium carbonate and sodium alginate could significantly improve the deterioration.SDS-PAGE and free sulfhydryl group analysis also showed that potassium carbonate could promote the disulfide bond cross-linking of frozen steamed bread in the freeze-thaw process,and then improve the macroscopic quality of steamed bread.Finally,the influence of compound improvers on the quality of frozen dough steamed bread during storage and freeze-thaw process was explored.The results showed that the specific volume of frozen dough steamed bread stored for 6 weeks was increased by 50%in the compound improvers group.The specific volume of frozen dough steamed bread freeze-thaw for 4 times was increased by 16.67%（p<0.05）.The height-diameter ratio of steamed bread in the frozen storage group for 6 weeks and the freeze-thaw group for 4 times increased by 31.58%and 62.8%,respectively.The results of texture and pore analysis also showed that the compound improvers could improve the decline of springiness and resilience of frozen dough steamed bread,and reduce the damage to the internal structure of frozen steamed bread during freezing storage and freeze-thaw process,and make the internal pores of steamed bread more uniform.