Quality Analysis On Persimmon Leaf Tea Of Different Varieties And Seasons And Study On The Optimal Processing Technology

Persimmon was widely distributed in China. Persimmon leaves had a variety of health functions because they were rich in polyphenols, vitamin C and other functional ingredients. Now, persimmon leaf tea mainly followed the traditional processing technology in our country. It had hindered the development and utilization of persimmon leaves because of its poor flavor and the lack of systematic research. The experiment studied the different varieties’seasonal variation in sensory quality and the key physical and chemical compositions. And it also explored the appropriate processing of the varieties that we selected.1. The sensory quality analysis on persimmon leaf of Different varieties and seasonsThe sensory quality scores of the most completely sweet persimmon varieties were on the rise from April to July, lower in August, and then gradually increased. The sensory quality scores of the most completely astringent persimmon varieties were on the decline from April to June, rose sharply in July, slightly lowered or rose afterwards. Two incomplete sweet persimmon varieties have quite different change trends, the16th variety’ sensory quality score kept growing from April to July, and reached the highest level for the whole year. But the seasonal change of the17th variety’ sensory quality score was relatively stable.According to the results of sensory quality, the9th variety’ sensory quality was best in April and May. In September, the sensory scores of the10th,6th,4th, and15th varieties were higher. In October, the sensory scores of the2th,11th,13th,4th,9th and15th varieties were higher. 2. The main quality components analysis on persimmon leaf of Different varieties and seasonsWater extract content:persimmon leaf tea’water extract content was between26.84%and44.71%. Most varieties’lowest value throughout the year occured in June or September, the highest value occured in May or October basically.Complete and incomplete sweet persimmon varieties’water extract content showed a rising trend from April to May, and then declined significantly. Until July or August, water extract content increased and decreased again in September.In October, it might reach the highest level throughout the year.Complete Astringent persimmon varieties’water extract content differed from other types. The13th,14th and15th varieties’water extract content kept rising from May to July and decreased afterwards. It rose again in October.Anthocyanin content: Anthocyanin content’s annual minimum of most varieties’ fresh leaves occured in May. May to July, anthocyanin content of the most completely sweet persimmon varieties’fresh leaves increased. Most of them were decreased in August and rose sharply to September or October.The change of completely astringent persimmon varieties’fresh leaves’anthocyanin content was less than the other two types’ varieties. But the change trend was similar to the completely sweet persimmon varieties. Incomplete sweet persimmon varieties’change trend was slightly different. The16th variety’s anthocyanin content kept rising from May to October. But the growth rate was less than the17th variety.Polyphenol content:persimmon leaf tea’ polyphenol content was between4.07%and12.29%. Polyphenol content’s annual maximum occured in May basically. In May, the polyphenol content of the10th,9th, lth,2th,15th,11th,6th and3th varieties was higher. Completely sweet persimmon varieties’polyphenol content fell sharply from May to July, and then kept steady. Completely astringent persimmon varieties were different, they lowered or rose slightly in August or September. Incomplete sweet persimmon varieties’polyphenol content showed a rising trend from April to June and then kept declined. Vitamin C content: VC content of persimmon leaf tea was very high, the number of varieties whose VC content’s annual average was higher than9mg/g accounted for76.47%. VC content’s annual maximum occured in May basically. In May, the VC content of the10th,5th,7th,6th,3th,8th,17th and9th varieties was higher. VC and polyphenol content’s change trends were similar, but the Change ranges of these two components were not in proportion.Soluble sugar content: persimmon leaf tea’Soluble sugar content was between11.35%and15.10%. Soluble sugar content’s annual maximum occured in May basically. The content declined obviously to June. It rose again in September or October. Annual maximum of completely astringent persimmon varieties’sugar content also occured in May. It lowered sharply in June and then kept steady. In October, there was a slightly rising trend. Incomplete and complete sweet persimmon varieties’change trends were similar.3. Study on the optimum processing of different varietiesthe optimum processing technologies of different varieties and seasons’persimmon leaves were different. The9th variety’s persimmon leaves were processed as three different kinds of processing technologies in May and September. The persimmon leaf tea tasted sweet and had fresh fragrance or the fragrance of sweet potato. It showed that the9th variety were suitable for processing as the three kinds of technology. The15th variety’s persimmon leaf was more suitable for processing as the technology Ⅱ in May. The product had sweet potato’s aroma and tasted good. But the aroma of the tea which processed as the technology I in September was best. The most suitable technology to the17th variety was also the technology Ⅰ. The analysis on chemical composition showed that the technology Ⅰ was more advantageous to polyphenols and vitamin C’s retention. The technology Ⅲ was conducive to the embedded component’s transformation and the accumulation of water content.