Effects Of Drying Temperature On The Yield Of Total Flavonoids From Three Varieties Of Cassava Leaves And Its Mechanism

At present, cassava leaves are one of the major byproducts of cassava production,with large yields. Cassava leaves are rich in flavonoids and have great potential for development. In this paper, three species of cassava leaves (South China No.7, South China No.9 and South China No.205) were selected as the experimental materials, and the method of purification of the crude extract of cassava leaves was optimized and the color conditions were determined. The yield of total flavonoids at 40?, 60?, 80?, 100?,120?, 14? and 160? drying temperature was studied. The effects of liquid phase The yield of six flavonoids was determined by HPLC-MS. The results showed that the flavonoids were identified and analyzed. The results are as follows:(1) Three species of purification methods, the best effect of polyamide resin, followed by macroporous adsorption resin, solvent extraction the worst. However, the results showed that the macroporous adsorption resin was in accordance with the requirements(115.40%, RSD 3.16%). Macroporous adsorption resin was used as the crude extract of cassava leaves.(2) Optimization of colorimetric conditions showed that Al(NO3)3 solution could be added after adding NaNO2 solution. After NaOH solution was added for 4 min, the results were better after standing for 10 min. The final color time from the original 22 min to 14 min, effectively shortened the 8 min, so that the determination of faster and more efficient.After the methodological study, a rapid and efficient method for the determination of total flavonoids was established.(3) The effects of different drying temperature on the yield of total flavonoids in cassava leaves were different, and the maximum drying rate of total flavonoids in cassava leaves was different. The yield of total flavonoids in cassava leaves of South China No.7 showed"rise-down" trend with the increase of drying temperature, and reached the maximum of 2.50% at 100?. The yield of total flavonoids in cassava leaves of South China No.9 showed "rise-down-rise-down" trend with the increase of drying temperature The results showed that the yield of total flavonoids in cassava leaves of South China No.205 was the same as that of South China No.9, which was higher than that of South China No.9 Similar,also showed "rise-down-rise-down" trend. Except that the peak values of 2.51% and 2.47%of the total flavonoids in the cassava leaves of South China No.205 were obtained at the drying temperature of 80? and 140? , respectively. From the varieties of consideration,South China No.7 and No.205 cassava leaves total flavonoids production rate higher than the South China No.9.(4) The results showed that rutin was the main component of the flavonoids of cassava leaves, accounting for 40%-50%, which was much larger than the sum of the other five flavonoids. The change was the same as that of the total flavonoids. The results showed that 57 flavonoids were identified by qualitative analysis. Among them, luteolin,paeoniflorin and violet cloud were used to study the changes of total flavonoids in the process of drying. Glycosides, isoquercitrin and glycosides and other elements led by a variety of flavonoids for the first time found.