The third crop of green tea leaves contains a relatively large amount of catechins, resulting in a bitter taste to the hot-water extract of its leaves. On the other hand, loquat leaves have a strong enzymatic activity that can oxidize catechins. They also contain chlorogenic acid, which accelerates the oxidation of catechins. Thus, we tried to promote the oxidative polymerization of catechins in third-crop green tea leaves by the addition of loquat leaves, and presumed that the taste of the third-crop green tea would be improved. However, the active ingredients contained in loquat leaves are difficult to extract with hot water due to the hardness of the leaves. Thus, we mixed and kneaded the third-crop green tea leaves and loquat leaves together using the tea roller of a tea manufacturing machine, which may have facilitated the elution of the components contained in loquat leaves, and may have effectively promoted the oxidation of catechins contained in the third-crop green tea. In this study, we improved the conventional method of producing black tea leaves, and developed a method for producing new high-quality mixed and fermented tea using the third crop of green tea leaves and loquat leaves, which were previously unused resources. We outline our main efforts here.
緑茶を対象としてretroposon-like sequence DNA (RLS-DNA）塩基配列の比較解析により品種の判別を試みた．実験には，やぶきた品種のチャ葉より製造した緑茶と，市販されている中国，ベトナム，ミャンマー，台湾の緑茶，そして日本の緑茶用40品種の生茶葉を用いて実験した．RLS-DNAの塩基配列を比較解析することにより，おくみどり，べにふうき等の品種の判別が生茶葉と緑茶葉を用いた場合，共に可能であることが認められた．また，中国，ベトナム，ミャンマー，台湾の緑茶についてもRLS-DNAの多型解析により我が国の緑茶と識別可能であることが認められた．今回の実験から，RLS-DNAを指標とした塩基配列の多型解析は，おくみどり，べにふうき品種等の品種を判別するための手法に適用できるものと考える.