| Niandoubao is a characteristic traditional food in Northeast China.The fusion of food culture in the north and south has made Niandoubao more popular.However,most of the Niandoubao production is made by small workshops and small companies are made by traditional natural fermentation.It has complex procedures,long fermentation cycles,and Disadvantages such as poor security.Therefore,the need for standardization and standardization of batch production of Niandoubao is particularly urgent.Compared with traditional natural fermentation,artificial inoculation of lactic acid bacteria starter to make Niandoubao can significantly overcome the disadvantages of the above-mentioned traditional fermentation.In addition,the changes in nutritional components during the fermentation process of Niandoubao and the influence of frozen storage on its eating quality have not been reported.Therefore,it is necessary to conduct corresponding research to obtain a better production process and the changing law of frozen storage quality to provide guidance for actual production.So the research results are as follows.(1)Taking sensory scores,hardness,elasticity,adhesiveness and cohesion as evaluation indicators,based on single factor test results,using Box-Behnken test design to optimize process conditions to obtain the best process parameters:raw material ratio(glutinous rice:japonica rice)=80:20(g/g),lactic acid bacteria added amount=7%(v/v),fermentation time=20 h,fermentation temperature=37?.The glutinous rice Niandoubao produced under these conditions has good texture and sensory qualities.(2)Select the optimal production conditions to prepare Niandoubao,and explore the changes in its nutrient composition during fermentation.The study found that as the fermentation time increases,the total acidity of the fermentation broth and the number of viable lactic acid bacteria first increase rapidly and then tend to However,the pH value is just the opposite;the content of lactic acid in organic acids has always been on the rise,while other organic acids have shown a downward trend as a whole,and oxalic acid reaches its lowest value during 8-12 hours of fermentation;the types and quantities of free amino acids have increased significantly.The increase in the ratio of essential amino acids makes the Niandoubao more nutritious,which is beneficial to the body's absorption.(3)Frozen storage is a common preservation method for waxy food,but it will have an important impact on the texture and eating quality of Niandoubao.Therefore,this experiment comprehensively evaluates the quality of glutinous rice Niandoubao after routine freezing through low-field nuclear magnetic resonance(NMR),texture testing and sensory evaluation methods.As the number of frozen storage days increases,the hardness,elasticity,adhesiveness and cohesiveness and sensory scores of the Niandoubao after re-steaming show a downward trend,and combined with the T2 relaxation curve and the moisture binding state,the signal strength is gradually weakened.,That is,the total water content decreases,mainly due to the high content of free water in frozen Niandoubao,and free water is a part of the water that is easily lost during the freezing process of cooked dough.There are three different forms of water during the freezing process,namely,strongly bound water,weakly bound water and free water,while the frozen cooked dough of Niandoubao is mainly free water.According to the peak areas corresponding to the relaxation times T21,T22 and T23,it can be seen that for unfrozen cooked Niandoubao dough,frozen storage significantly increases the strong bound water of the frozen cooked dough,but as the number of frozen storage days increases,The strong bound water of frozen cooked dough showed a downward trend,while the free water showed an upward trend,and the difference was not significant.This research can provide a certain theoretical reference for cold chain transportation,Niandoubao preservation,and factory shelf life setting. |
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