Study On Effects Of Glutinous Rice Varieties On The Quality And Shelf Life Of Rice Dumplings

Rice dumplings is a traditional Chinese food,which is deeply loved by the public for its unique sensory quality.In this experiment,the effects of different varieties of glutinous rice on sensory quality,flavor and shelf life of rice dumplings were studied.The prediction models of sensory quality,key aroma components and flavor of rice dumplings and shelf life were established.The main research contents,results and conclusions are as follows:(1)In order to explore the rapid prediction model of the sensory quality of rice dumplings,20 kinds of glutinous rice from different regions were used as raw materials to make rice dumplings.The physical and chemical properties of glutinous rice and the texture characteristics of rice dumplings were measured separately and combined with the sensory evaluation of rice dumplings.PLSR was used to establish the prediction model of the texture profile analysis(TPA)and physicochemical properties to the sensory quality of rice dumplings.The results show that based on TPA parameters,five sensory indicators can be predicted,with the best prediction for both masticatory and visual viscosity,R~2>0.9,and the RMSEE is small.This was followed by hardness(R~2=0.89,RMSEE=0.33)and chewiness(R~2=0.80,RMSEE=0.67).The use of the physical and chemical properties of glutinous rice can predict six sensory parameters,with visual inspection of viscosity being the best predictor with R~2=0.98,and the RMSEE was small(0.13).This was followed by hardness(R~2=0.71,RMSEE=0.54),rice fragrance(R~2=0.65,RMSEE=1.31)and gloss(R~2=0.61,RMSEE=1.05).The R~2of the TPA prediction model was significantly higher than that of the physicochemical characteristic prediction method.It is inferred that the TPA prediction model is better than the prediction model of physical and chemical indicators,and overcomes the subjectivity of traditional sensory evaluation,which is more suitable for the evaluation of sensory quality of rice dumplings.(2)Six varieties of glutinous(Japonica glutinous rice:LJ?TN1?HN2,Indica glutinous rice:JGN?DBN?NLN)rice packets were selected to make white rice dumplings.The aroma components of rice dumplings were analyzed by HS-SPME-GC-MS,and 49 kinds of aroma compounds were detected.The results showed that:According to the evaluation of the flavor attributes of rice dumplings,it was found that japonica glutinous rice dumplings had strong sweet,light,oil and tobacco flavors,while indica glutinous rice dumplings had strong raw grain and bitter flavors.The flavor of Japonica glutinous rice dumplings was better than that of indica glutinous rice dumplings,and the flavor quality of HN2 japonica glutinous rice dumplings was the best.23kinds of characteristic compounds were selected,and the prediction model of key aroma compounds on the flavor properties of rice dumplings was established.It was found that the aroma compounds could predict the flavor properties of rice dumplings well,including 6 flavor properties,i.e.light flavor,raw grain flavor,sweet flavor,bitter flavor,oil flavor and cooked grain flavor,but the prediction effect on acid flavor and tobacco flavor was not ideal.(3)Two varieties(Japonica glutinous rice:HN2,Indica glutinous rice:JGN)of rice dumplings were selected to make rice dumplings,and stored at 4 and 25?for 7 days respectively.The microbial,texture properties and sensory quality of rice dumplings were monitored dynamically.The results showed that:During the storage of rice dumplings,with the extension of time,the microorganism,hardness,adhesiveness and chewiness of rice dumplings gradually increase,while the moisture,elasticity,viscosity and sensory quality gradually decrease.The quality indexes accelerate to change with the increase of storage temperature,which makes the overall quality of rice dumplings decline.Through the accuracy analysis of the shelf-life prediction model established by each quality index of rice dumplings,it is found that the key factor affecting the storage quality of rice dumplings is water content.Through the first-order kinetic equation combined with Arrhenius equation,the prediction shelf-life model of rice dumplings moisture was established.The prediction error of two kinds of glutinous rice dumplings at different storage temperatures was small,and the prediction accuracy was good.