2015 Volume 2015 Issue 119 Pages 119_21-119_28
Characteristic off-flavor derived from the so-called “Natsucha-shu” is one of the major problems in summer crop of green tea. Until now, the authors made a finding that a low-temperature (19℃) storage of fresh tea leaves before steaming (LTS) improved the off-flavor of “Natsucha-shu”. Therefore, the scope of this research is to elucidate “Natsucha-shu” improvement caused by the LTS. An aroma extract dilution analysis (AEDA) has been applied to the volatile fractions isolated from the sen-cha, processed through the LTS. AEDA have revealed that (Z)-1,5-octadien-3-one，2-isopropyl-3-methoxypyrazine, 2-isobutyl-3-methoxypyrazine, (E,Z)-2,6-nonadienal, 3-methylnonane-2,4-dione and furaneol were detected as prevalent odorants in sen-cha with “Natsucha-shu”: while 4 odorant, namely, linalool, β-damascenone, (Z)-methyl jasmonate, indole were potent odorants present in sen-cha, processed through the LTS without “Natsucha-shu”. The semi-quantitative analysis and additive test of odorants clarified that methoxypyrazines as causing agents of “Natsucha-shu” were stable during the LTS, and increased odorants caused by the LTS would be a capable of masking the “Natsucha-shu”.
