Parker Mango, Pollnitz Alan P, Cozzolino Daniel, Francis I Leigh, Herderich Markus J
The Australian Wine Research Institute, P.O. Box 197, Glen Osmond (Adelaide), SA 5064, Australia.
J Agric Food Chem. 2007 Jul 25;55(15):5948-55. doi: 10.1021/jf0705320. Epub 2007 Jun 20.
'Black pepper' aroma and flavor is important to some Australian Shiraz red wine styles but the aroma compounds involved have yet to be identified, and no objective analytical method to assess 'pepper' grape aromas is available to date. Samples of potentially 'spicy'/'peppery' grapes were obtained from vineyards in South Australia and Victoria over two vintages. The important sensory attributes of the grapes, including the aroma descriptor 'pepper', were rated by a sensory panel. The sensory study revealed a strong correlation between the intensity of 'pepper' aroma and the intensity of 'pepper' flavor perceived on the palate. The grape homogenates were analyzed by static headspace GC-MS using a cool inlet system. Vectors obtained by analysis of over 13 000 individual mass spectra per grape sample were then subjected to multivariate analyses. Both principal component analysis and partial least-squares regression were used to develop multivariate models based on mass spectra and aroma descriptors to explain the intensity of the rating of the 'pepper' character. Corresponding differences in mass spectra and aroma were observed among vineyards and from the same vineyards in different years. Additional optimization of the methodology enabled selection of a single region of the GC-MS chromatogram that allowed prediction of 'pepper' aroma intensity with a correlation coefficient >0.98 and led to the identification of alpha-ylangene, a tricyclic sesquiterpene. To assess the potential of alpha-ylangene as a marker for this sensory characteristic, a method for alpha-ylangene analysis of grapes and wine using HS-SPME-GC-MS was developed. Although not a significant aroma compound by itself, alpha-ylangene was a satisfactory marker for the 'pepper' aroma in grapes and wine, and its concentration showed similar discrimination between 'peppery' vineyards and vintages as that obtained using the multivariate models. Despite its presence in grapes, we could not detect alpha-ylangene in wine.
“黑胡椒”香气和风味对某些澳大利亚设拉子红葡萄酒风格很重要，但其中涉及的香气化合物尚未确定，而且迄今为止尚无客观的分析方法来评估“胡椒”葡萄香气。在两个年份期间，从南澳大利亚和维多利亚州的葡萄园获取了可能具有“辛辣”/“胡椒味”的葡萄样品。由一个感官小组对葡萄的重要感官属性进行评分，包括“胡椒”香气描述词。感官研究表明，“胡椒”香气强度与口腔中感知到的“胡椒”风味强度之间存在很强的相关性。使用冷进样系统通过静态顶空气相色谱 - 质谱联用仪对葡萄匀浆进行分析。然后对每个葡萄样品分析超过13000个个体质谱图所获得的向量进行多变量分析。主成分分析和偏最小二乘回归都用于基于质谱图和香气描述词建立多变量模型，以解释“胡椒”特征评分的强度。在不同葡萄园以及同一葡萄园不同年份之间观察到质谱图和香气的相应差异。该方法的进一步优化使得能够选择气相色谱 - 质谱联用仪色谱图的单个区域，该区域能够以大于0.98的相关系数预测“胡椒”香气强度，并导致鉴定出α-衣兰烯，一种三环倍半萜。为了评估α-衣兰烯作为这种感官特征标志物的潜力，开发了一种使用顶空固相微萃取 - 气相色谱 - 质谱联用仪分析葡萄和葡萄酒中α-衣兰烯的方法。尽管α-衣兰烯本身不是一种重要的香气化合物，但它是葡萄和葡萄酒中“胡椒”香气的令人满意的标志物，其浓度在“胡椒味”葡萄园和年份之间表现出与使用多变量模型所获得的类似区分。尽管它存在于葡萄中，但我们在葡萄酒中未检测到α-衣兰烯。
