Study On The Effects Of Typical Waxy Rice Varieties On The Textural Quality Of Zongzi

Waxy rice is a sticky variety of ordinary rice,with extremely high amylopectin content,and there are 10,370 kinds of varieties recorded at present in China.Zongzi is a product made by waxy rice,wrapped with reed leaves,and cooked in boiled water.It is favored by people because of unique texture quality.Different varieties of waxy rice have differences in genetic traits,processing quality,edible quality and so on,so selecting suitable waxy rice varieties to making Zongzi is great significance for its quality.Studies on the effect of waxy rice varieties on the texture quality of Zongzi are relatively rare,therefore,the purpose of this paper is to explore the influence of waxy rice varieties on the texture quality of Zongzi,and clarify the demands for waxy rice for Zongzi.In this paper,15 different varieties of waxy rice were used as raw materials to wrap Zongzi and a comprehensive evaluation model of Zongzi texture quality was constructed.The texture quality of each sample was determined.The influencing factors of the texture quality of Zongzi were explored in the perspectives of kernel structure and properties,fine structure and physical and chemical properties of waxy rice starch.Finally,the specific requirements of waxy rice for Zongzi were summarized.The research contents of this paper are as follows:Firstly,15 varieties of waxy rice were wrapped into Zongzi,the texture quality of Zongzi was measured,the matching degree between TPA and sensory evaluation was investigated,and a comprehensive evaluation model of Zongzi texture quality was established.The results showed that differences among different varieties of Zongzi were observed between texture indicators,such as hardness,adhesiveness,springiness,cohesiveness and chewiness.According to the above differences,15 Zongzi samples can be divided into three categories:excellent quality Zongzi（Z5,Z7,Z8,Z14 and Z8）,qualified quality Zongzi（Z1,Z4,Z6,Z9,Z10,Z11,Z12 and Z13）and unqualified quality Zongzi（Z2,Z3）.All the sensory evaluation indexes were significantly correlated with TPA indexes,and the high matching degree and the strong consistency of the two results were found,which indicating that TPA could simulate human oral sensation and accurately measure the texture quality of Zongzi.The principal component analysis method was used to obtain the comprehensive evaluation model of Zongzi texture quality,F=0.559F1+0.269F2+0.159F3.Secondly,the whole and part structures of different varieties of waxy rice were observed through different means and dimensions.Water adsorption characteristics and pasting characteristics were explored to discover the influence of kernel structure on the texture quality of Zongzi during the production process.The results show that waxy rice for excellent Zongzi has the characteristics of round kernel,small aspect ratio（above 1.60～1.70）and low density.The starch granules in the marginal part of the rice were small and tightly arranged,the wideness of"protein layer"was moderately,and the endosperm cells in the central part were regularly arranged and uniform both in size and shape.The different structures of waxy rice kernels made the differences in water adsorption and pasting characteristics,which in turn to different textural qualities of Zongzi.Finally,the differences in the fine structure and properties of waxy rice starch were analyzed,and the correlation between waxy rice starch and the textural quality of Zongzi were investigated.Starch particle size D50,average chain length,group A,group B₁ and relative crystallinity were significantly correlated with the F,F1,F2 and F3.Detailed,F2 was positively correlated with the group A（r=0.53,P<0.05）while negatively correlated with the group B₁（r=-0.53,P<0.05）.There was a significant positive correlation between relative crystallinity and F1（r=0.56,P<0.05）.Starch gelatinization temperature（To,Tp and Tc）were negatively correlated with F1 and F.The peak viscosity was negatively correlated with F3（r=-0.70,P<0.01）and the hold viscosity was negatively correlated with F（r=-0.51,P<0.05）.The final viscosity was significantly correlated with F1,F3 and F,with the correlation coefficients-0.54,-0.57 and-0.61,respectively.Starch solubility was positively correlated with F1 and F（r=0.72,P<0.01;r=0.63,P<0.03）.