ニンジンの雪下貯蔵に伴う香気成分の変化(収穫後の貯蔵・流通)  [in Japanese] Change in Volatile Compounds in Carrot Stored under Snowy Ground(Postharvest Physiology & Technology)  [in Japanese]

試料の雪下貯蔵ニンジンは1998年12月7日から1999年4月12日にかけ, ほぼ1か月ごとに積雪前あるいは積雪下の土中より採取した.香気成分の分析はニンジン香気成分のジクロロメタン抽出物を用い, 常法に準じてガスクロマトグラフィー(以下, GC)およびガスクロマトグラフィー-質量分析(以下, GC-MS)により行った.GCおよびGC-MS分析の結果, 各試料より100〜124のピークが検出され, このうち, 雪下貯蔵ニンジンの香気成分として45化合物を同定した.同定した化合物のうち, 26化合物は著者らが初めてニンジンの香気成分として検出した.ニンジンの香気成分量の指標となるピーク総面積値は, 1998年12月〜3月(以下, 12月〜3月)の間ほとんど変化は認められなかったが, 1999年4月(以下, 4月)には12月〜3月に比べ約2.7倍に増加した.雪下貯蔵ニンジンの主なる香気成分は, β-caryophyllene, caryophyllene oxide, borneol, bornyl acetate, trans-α-bisaboleneなどであった.これらのうち, β-caryophylleneは雪下貯蔵に伴い大きく増加し, 4月には12月に比べ12.8倍に増加した.またこの化合物は4月の総香気成分の32.3%を占め, 12月に占めた割合の4.8倍であった.β-caryophylleneと同様, 雪下貯蔵に伴い増加傾向にあった香気成分はtrans-α-bisabolene, α-humulene, β-bisaboleneなどであった.そして, 12月〜3月の間ほとんど変化がなく, 4月に急激に増加した香気成分としてcis or trans-γ-bisaboleneが検出された.この化合物は4月の香気成分のうち28.4%を占め, β-caryophylleneに次いで多かった.一方, 雪下貯蔵に伴い減少したのがcaryophyllene oxide, borneol, bornyl acetate, α-humulene oxide, ρ-methylacetophenone, 6-methyl-(E, E)-3, 5-hepta-dien-2-oneなどであった.

Carrots stored under snowy ground from 98/12/7 to 99/4/12 were dug up and sampled each month. Volatile compounds of carrots were isolated and identified by gas chromatography and gas chromatography/mass spectrometry. One hundred to 124 compounds were found in each sample. Among a total of 45 compounds identified, 26 were identified for the first time in carrots. Concerning the amount of volatiles in carrots in the period between 98/12-99/3, there was almost no change. In comparison to these findings, in April of 1999, the total of volatile compounds had increased about 2.7 times. The main volatile compounds of carrots were β-caryophyllene, caryophyllene oxide, borneol, bornyl acetate and trans-α-bisabolene. Among these, the amount of β-caryophyllene showed an increase of 12.8 times in April compared to that in December. Further, in April this compound accounted for 32.3% of the total of volatile compounds. Similar to β-caryophyllene, trans-α-bisabolene, α-humulene, β-bisabolene all contributed to the increase in volatile components. Moreover, as for volatile compounds that increased sharply in April, cis or trans-γ-bisabolene were found. This compound accounted for 28.4% of all volatile components in April. Conversely, volatile compounds that decreased were caryophyllene oxide, borneol, bornyl acetate, α-humulene oxide, p-methylacetophenone and 6-methyl-(E, E)-3, 5-heptadien-2-one.