Midwest Grape and Wine Industry Institute, Iowa State University, Ames, IA 50011, USA.
Interdepartmental Toxicology Graduate Program, Iowa State University, Ames, IA 50011, USA.
Molecules. 2019 Feb 1;24(3):536. doi: 10.3390/molecules24030536.
In this research, we propose a novel concept for a non-destructive evaluation of volatiles emitted from ripening grapes using solid-phase microextraction (SPME). This concept is novel to both the traditional vinifera grapes and the cold-hardy cultivars. Our sample models are cold-hardy varieties in the upper Midwest for which many of the basic multiyear grape flavor and wine style data is needed. Non-destructive sampling included a use of polyvinyl fluoride (PVF) chambers temporarily enclosing and concentrating volatiles emitted by a whole cluster of grapes on a vine and a modified 2 mL glass vial for a vacuum-assisted sampling of volatiles from a single grape berry. We used SPME for either sampling in the field or headspace of crushed grapes in the lab and followed with analyses on gas chromatography-mass spectrometry (GC-MS). We have shown that it is feasible to detect volatile organic compounds (VOCs) emitted in-vivo from single grape berries (39 compounds) and whole clusters (44 compounds). Over 110 VOCs were released to headspace from crushed berries. Spatial (vineyard location) and temporal variations in VOC profiles were observed for all four cultivars. However, these changes were not consistent by growing season, by location, within cultivars, or by ripening stage when analyzed by multivariate analyses such as principal component analysis (PCA) and hierarchical cluster analyses (HCA). Research into aroma compounds present in cold-hardy cultivars is essential to the continued growth of the wine industry in cold climates and diversification of agriculture in the upper Midwestern area of the U.S.
在这项研究中，我们提出了一个使用固相微萃取（SPME）对成熟葡萄释放的挥发性物质进行无损评估的新概念。这个概念对于传统的酿酒葡萄和耐寒品种来说都是新颖的。我们的样本模型是中西部地区的耐寒品种，需要许多多年来的葡萄风味和葡萄酒风格的基本数据。无损采样包括使用聚偏氟乙烯（PVF）室暂时封闭和浓缩葡萄藤上整串葡萄释放的挥发性物质，以及一个改良的 2 毫升玻璃小瓶，用于从单个葡萄浆果中真空辅助采集挥发性物质。我们使用 SPME 进行现场采样或实验室中压碎葡萄的顶空采样，并随后进行气相色谱-质谱（GC-MS）分析。我们已经证明，从单个葡萄浆果（39 种化合物）和整串葡萄（44 种化合物）中检测体内释放的挥发性有机化合物（VOCs）是可行的。从压碎的浆果中释放出超过 110 种 VOC 到顶空。对所有四个品种都观察到了 VOC 图谱的空间（葡萄园位置）和时间变化。然而，通过多元分析（如主成分分析（PCA）和层次聚类分析（HCA））分析，这些变化在生长季节、位置、品种内或成熟阶段并不一致。对耐寒品种中存在的香气化合物的研究对于寒冷气候下葡萄酒行业的持续发展和美国中西部地区农业的多样化至关重要。
