Study On The Effect Of Ferments On The Quality Of Foxtail Millet Steamed Bread During Processing

Steamed bread,the main staple food of Chinese people;Foxtail millet is a traditional Chinese grain crop,which has high nutritional value.Adding foxtail millet flour to the steamed bun recipe can improve the nutritional value of steamed bread.In the production of foxtail millet steamed bread,the core element that affects the sensory quality of the bread is fermentation.Therefore,it is important to investigate the law of fermentation agent on the quality formation of foxtail millet steamed bread during processing.In this thesis,a mixture of foxtail millet flour and flour was used as raw material,and the basic nutrients and pasting characteristics were measured to determine the optimal ratio of raw material.On this basis,four different fermenting agents yeast,sour dough,compound lactic acid bacteria,and wine malt were combined with the raw materials respectively to prepare the dough and then fermented for different times to investigate the changes of physicochemical properties of foxtail millet dough and the quality characteristics of its finished steamed bread,so as to provide theoretical guidance for enhancing the added value of foxtail millet and improving the industrialized production of steamed bread.The main conclusions are as follows.（1）The effects of different fermentation agents on the product quality of raw material flours and fermented doughs during processing were investigated through experiments to determine the basic nutritional composition and pasting characteristics of three different raw material flours and the physicochemical characteristics of different fermented doughs.The results showed that the blended flour was more acceptable to the general population in terms of basic nutritional composition.The pasting characteristics showed that the mixed flour had a regeneration value of 1065.67cp and produced a more stable dough.The hydration characteristics showed that the blended flour contains more hydrophilic groups and has a higher water absorption index,which makes a better quality product.The thermomechanical damage showed that the stabilization time of the mixture was 4.93 min and the protein weakness was reduced to1.19（N·m）,which indicated that the dough produced was more glutenous and had better kneading resistance.Meanwhile,the chromaticity and rheology of the fermented doughs showed that:the differences in chromaticity of the four fermented doughs were more obvious;the p H of the four fermented doughs showed a decreasing trend,and the fermentation time of the sour dough showed a linear relationship with the p H,with R²of 0.9889;the water retention of the doughs was better according to the peak time of T₂₁,which was compound lactic acid bacteria dough>sour dough>wine bran dough>yeast dough in order.All systems of the four fermented doughs were dominated by the nature of elastic fluid.It is known from SEM that the starch granules have a large amount of protein attached to the surface,which is beneficial to the extension of gluten protein and the formation of gluten protein network.（2）The effects of different ferments on the quality of steamed bread at different fermentation times were investigated by measuring the specific volume,texture and flavor of foxtail millet steamed bread.The texture analysis showed that the steamed bread swelled best and had soft texture at 80 min of fermentation for yeast steamed bread,180 min of fermentation for sourdough steamed bread,120 min of fermentation for compound lactobacillus steamed bread,and 100 min of fermentation for wine bran steamed bread,which were easily accepted by consumers.The sensory evaluation showed that making sour dough from yeast,compound lactobacillus and sour dough from wine bent could improve the overall sensory score of steamed bread and the steamed bread were more popular and the results were consistent with the texture theory values.The GC-MS analysis revealed that the microbial populations in the same fermenter differed greatly,resulting in different metabolic consumption of nutrients in the environment and different flavor substances produced.The variance contribution of volatile components of the four fermented steamed bread was found to be above 95%by electronic nose probing.（3）By analyzing the correlation of foxtail millet steamed bread during processing,the influence of different fermentation agents on the correlation of steamed bun quality during processing was investigated.The correlations of four different fermentation agents on the dough during processing showed positive correlations except for the color and pasting characteristics of yeast dough,and negative correlations existed between each data of the other three different fermentation agents steamed bread;significant positive correlations were found between the sensory indexes and TPA of the four steamed bread;the prediction of TPA and sensory evaluation models of the four steamed bread showed that the coefficient of determination R2 of each equation was greater than0.5;the four The principal component analysis and heat map analysis of the volatile components of different ferments showed that nonanal and decanal were less in the old noodles and compound lactobacillus steamed bread.In addition,compared with yeast steamed bread,the other three ferments and steamed bread had higher content of esters and alkenes.