Study On The Quality And Biochemical Characteristics Of Wencheng Yam Starch

Wencheng Chinese yam is a unique and excellent local variety in Wencheng County,Wenzhou City,Zhejiang Province.It has strong waxy traits,high research and development value.This paper systematically studies the quality and starch biochemical characteristics of Wencheng yam from the aspects of the composition and characteristics of yam starch,the dynamic law of quality changes during the growth and development of yam,the comparison of yam quality of different cultivation methods and the cross-linking characteristics of protein and starch.The main findings are as follows:1.Comparing the molecular structure and physicochemical properties of Wencheng yam,Tiegun yam and Huai yam starch,it was found that Wencheng yam starch had the highest proportion of amylopectin and largest weight average molecular weight,number average molecular weight and particle size,and at the same time had the highest gelatinization temperature,enthalpy value,peak viscosity and swelling power.The three starches were all CB-type crystalline,and showed similar short-range ordered structures.The gel properties,gelatinization properties and swelling ability of yam starch were significantly related to the amylopectin content.2.The effect of protein on the composition,structure and physicochemical properties of yam starch was studied.The protein was cross-linked with starch molecules through hydrogen bonds and showed a restriction on the starch swelling process.After the starch and protein were cross-linked,the gelatinization temperature was increased,the peak viscosity and the regenerated viscosity were reduced,and the water solubility and swelling power were weakened.Laser confocal results showed that the cross-linking of protein and starch could limit the thermal swelling ability of starch.3.The full-length 1811 bp waxy gene sequence of Wencheng Yam was obtained by sequencing,and the granule-bound starch synthase sequence of yam was compared and analyzed.Wencheng yam had the lowest expression of waxy gene,which explained the lowest amylose content in Wencheng yam.4.During the growth and development of yam,the starch content in Wencheng yam rose first and then stabilized,while the proportion of amylose,protein content and reducing sugar content decreased to a lower level during the mature stage.Correlation analysis showed that the proportion of amylose was significantly related to the viscosity,adhesiveness and chewiness of the texture test indicators.Therefore,the viscosity,adhesiveness and chewiness indicators were used as the main parameters to evaluate the waxy traits of yam.Calculation formula of performance value was established.5.Comparing the yam composition and starch texture of 4 cultivation modes,including open-air natural cultivation,open-air casing cultivation,greenhouse natural cultivation,and greenhouse casing cultivation,it was found that the protein content of casing-cultivation yam was higher,while the open-air cultivation method made reducing sugar content reduced.The planting method had no significant effect on the accumulation of starch.The non-casing planted Wencheng yam starch had strongest waxy traits.The main function of casing planting was to make the yam more beautiful in appearance and convenient for transportation and processing.