Environmental Variation of the Chemical Constituents of the Tea Leaf

Abstract

1. The tea leaves of the varieties of Yabukita (for green tea) and Benihomare (for black tea) were collected from Kagoshima, Shizuoka and Saitama prefectures on the first, second and third plucking seasons during the three years from 1949 to 1951, and the regional variations of the chemical constituents of the leaves as well as the hot hydrochloric acid soluble components of the garden soil on which the sample plants were grown were researched.2. The analyzed constituents contained total-N, soluble-N, caffeine, tannin, hot water extract, crude fiber, crude ash, and alkalinity of ash. From the above-mentioned data, insoluble-N, caffeine-free soluble-N, the ratios of N-Fractions with each other, the ratios of soluble-N or tannin in the hot water extract were calculated.3. The analysis of variance of the chemical constituents showed the following significant level of F value on the principal sources of variation which were the year, the variety, the locality, and the season.4. As for the annual variation, soluble-N. caffeine, crude fiber, and crude ash were most abundant in 1950 and least in 1951, while tannin and alkalinity of ash showed the opposite tendency. And total-N, insoluble-N, caffeine-free soluble-N were least in 1949.The annual variation was considered to be affected by the climatic factors, but a decisive relation between the annual variation of the chemical constituents of the tea leaves and the climatic data could not be obtained, so far as this survey concerned.5. On the varietal difference, Yabukita contained more insoluble fraction of the nitrogenous contsituents while Benihomare contained more soluble part. The ratio of these fractions to the total-N showed the same tendency. It was favorable that the ratio of caffeine-free soluble-N to total soluble-N or that to hot water extract was higher in the Yabukita variety for the green tea, but the content of caffeine-free soluble-N and its ratio to hot water extract of this variety were remarkably reduced in the summer crop than the spring one, and this fact explained the deterioration of the qualities of tea made with Yabukita in summer. And it was also reasonable that Benihomare for black tea contained more tannin and hot water extract and showed higher ratio of tannin/riot-water-extract.6. The local variation which was the main purpose of this research brought about the following results.i) The content of ash and its alkalinity of the tea leaves indicated the most significant difference which was due to the soil components.ii) All nitrogenous constituents except caffeine and the ratios of N fractions with each other showed no significantt difference. This result seems to be favorable for increasing the excellent tea variety for green tea in every tea-producing district, as many analytical data bad shown the fact that the more the total-N, the better the quality of tea.iii) The tea leaves of the Kagoshima product was characterized by much crude fiber, and less crude ash and alkalinity. The ratio off tannin/hot-water-extract was much larger than the other two places. The local difference of the ratio was low in the spring crop but became higher in the summer crop, especially in the second season when the ratio was higher as the latitude of the producing district was lowered, so, it was recognized that the black tea production was advantageous in the southern region in Japan.iv) The Saitama product had the opposite characters to the Kagoshima one, with little fiber and much ash, eapecially in the summer.The soil of Saitama tea garden was very abundant in phosphoric acid and manganese. But the relation between soil components and ash of tea leaves or its alkalinity was proved significant only in the cases of soil iron-leaf ash and soil alumina-alkalinity of leaf ash with correlation coefficients of +0.903 and +0.960 respectively.