Analysis of Main Nutritional Components and Effects of Drying Methods on Main Functional Components Content and Color of Kyoho Grape Leaves

The main nutritional components were analyzed in leaves of Kyoho grape. The total flavonoids contents,resveratrol contents and color of the leaves by different drying methods(40℃ hot air,60℃ hot air,80℃ hot air and -48℃ vacuum freeze drying)were investigated. The results showed that the water content was 76.67%,the content of protein was 5.78%,dietary fiber 12.80 g/100 g,K 350 mg/100 g,Na 1 mg/100 g,Ca 15 mg/100 g,Mg 37 mg/100 g,Zn 2.2 mg/100 g,Fe 4.8 mg/100 g,Mn 23 mg/100 g and Cu 79 μg/100 g. The content of resveratrol and total flavonoids in Kyoho grape leaves reached the highest in the grape berry mature period,were respectively 424.34 μg/g and 95.27 mg/g. On the whole,treatments such as vacuum freeze drying was the best choice for drying of Kyoho grape leaves because it had good performance in maintaining color and active components(resveratrol and total flavonoids)in leaves. The second was 40℃ hot air drying,and the last was 80℃ hot air drying.