Aromatic Substances Evolved from the Whole Berry, Skin, and Flesh of Muscat of Alexandria Grapes

Volatile monoterpenes, evolved from the whole berries, skin, and peeled and unpeeled flesh (diced into 2×2×2mm blocks) of Muscat of Alexandria grapes, were measured by the head space method and GC analysis. Four kinds of monoterpene such as linalool and geraniol, known to be the main aromatic substances in Muscat of Alexandria berries, were analyzed. The highest levels of linalool and geraniol, expressed per 100g of samples per 3 hours, were evolved from the skin, followed by the juice, peeled flesh, unpeeled flersh, and whole berries, in descending order. Linalool and geraniol evolved from the skin were found to be at nearly the same level, though the levels of linalool from the juice and flesh were far higher than those of geraniol. The distribution of linalool among the various berry parts was highest in the juice, thoush that of geraniol was highest in the skin. Difference in the strength and quality of the aroma between peeled and unpeeled flesh were discussed. On the other hand, monoterpenes evolved from harvested whole berries increased rapidly for up to 2 days after, then decreased gradually until 7 days after. This change may be caused by the degradation of bound monoterpenes stored in the skin and flesh in excised fruit bunches.

‘マスカット・オブ・アレキサンドリア’の収穫果実について，果粒，果汁，皮，果肉（２㎜角に細断）からモンテルペンアルコールをヘッドスペース法によって捕集し，GCで分析した．マスカット香の主成分であるlinaloolとgeraniolなど４種のモノテルペンが分析された．生体重100 ，３時間当たりのモノテルペン捕集量は，皮からが最も多く，続いて，果汁，果肉，皮付きの果肉，果粒の順であった．皮からはlinaloolとgeraniolがほぼ同程度に得られたが，果肉や果汁からはlinaloolがはるかに多量に発散した．100 の果粒を構成する各部に含まれる香気成分の分布をみると，linaloolは果汁に最も多く含まれ，geraniolは皮に多く存在した．これらの結果から，剥皮または皮つきでマスカットの果実を食べる場合の，香りの強さと質の相違を検討した．一方，果粒から発散するモノテルペンは，収穫２日後に主要成分の発生量がピークとなり，その後減少して７日後には最低となった．この現象は，果実内に蓄積されたモノテルペンの配糖体が，収穫と同時に分解された結果と推察される．