Terpenes contribute to the desirable flavour and aroma of grapes and wine. The biosynthesis of these plant secondary metabolites is influenced by both physiological and environmental factors, such as grapevine phenological stage and sunlight exposure. In this study, we investigated the influence of ultraviolet (UV) at different grapevine phenological stages on free terpenes in grape at harvest. Two types of transparent polymer films were applied to grape bunches to eliminate both UV-A and UV-B or only eliminate UV-B, followed by the identification and quantification of terpenes using headspace solid-phase microextraction with gas chromatography–mass spectrometry (HS–SPME–GC–MS) analysis. In all, 27 free terpenes were identified, including eight monoterpenes/monoterpenoids, four norisoprenoids and fifteen sesquiterpenes. Higher concentrations of γ-terpinene, linalool and β-damascenone were observed in grapes with UV-B attenuation compared to the naturally exposed grape bunches. Elevated α-muurolene was observed in UV-attenuated grapes from pre-veraison to harvest, while higher concentrations of γ-cadinene were observed in naturally exposed grapes. The impacts of UV exclusion on grape terpenes at harvest were specific to phenological stages, where applying UV films from veraison to intermediate ripeness reduced the concentrations of key terpenes in grape harvest and UV attenuation from intermediate ripeness to harvest promoted the accumulation of α-muurolene and γ-cadinene. This study provides information for viticulturists to better manage grape terpene composition through UV shading.

中文翻译：

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紫外线对葡萄中游离萜烯产生的影响。设拉子

萜有助于葡萄和葡萄酒的所需风味和香气。这些植物次生代谢产物的生物合成受生理和环境因素（例如葡萄的物候期和日光照射）的影响。在这项研究中，我们调查了葡萄不同物候期的紫外线（UV）对收获时葡萄中游离萜烯的影响。将两种类型的透明聚合物薄膜应用于葡萄串，以消除UV-A和UV-B或仅消除UV-B，然后使用顶空固相微萃取-气相色谱-质谱（HS）对萜烯进行鉴定和定量–SPME–GC–MS）分析。总共鉴定出27个游离萜，包括8个单萜/单萜，4个去甲肾上腺素和15个倍半萜。与自然暴露的葡萄串相比，在具有UV-B衰减的葡萄中观察到了更高浓度的γ-松油烯，芳樟醇和β-大马烯酮。在从变态到收获期的紫外线衰减葡萄中观察到α-茂丁烯含量升高，而在自然暴露的葡萄中观察到较高浓度的γ-cadinene。紫外线在收获期对葡萄萜烯的排斥作用是物候学阶段特有的，在紫外线作用下，从正视到中熟，减少葡萄收获期关键萜烯的浓度，从中熟到收获期的紫外线衰减促进了α-茂烯和γ-cad烯。这项研究为葡萄栽培者通过紫外线遮挡更好地管理葡萄萜烯成分提供了信息。与自然暴露的葡萄串相比，在紫外线-B衰减的葡萄中观察到芳樟醇和β-大马烯酮。在从变态到收获前的紫外线衰减葡萄中观察到α-茂丁烯含量升高，而在自然暴露的葡萄中观察到较高浓度的γ-cadinene。紫外线在收获期对葡萄萜烯的排斥作用是物候学阶段特有的，在紫外线作用下，从正视到中熟，减少葡萄收获期关键萜烯的浓度，从中熟到收获期的紫外线衰减促进了α-茂烯和γ-cad烯。该研究为葡萄栽培者通过紫外线遮蔽更好地管理葡萄萜烯成分提供了信息。与自然暴露的葡萄串相比，在紫外线-B衰减的葡萄中观察到芳樟醇和β-大马烯酮。在从变态到收获前的紫外线衰减葡萄中观察到α-茂丁烯含量升高，而在自然暴露的葡萄中观察到较高浓度的γ-cadinene。紫外线在收获期对葡萄萜烯的排斥作用是物候学阶段特有的，在紫外线作用下，从正视到中熟，减少葡萄收获期关键萜烯的浓度，从中熟到收获期的紫外线衰减促进了α-茂烯和γ-cad烯。这项研究为葡萄栽培者通过紫外线遮挡更好地管理葡萄萜烯成分提供了信息。在从变态到收获前的紫外线衰减葡萄中观察到α-茂丁烯含量升高，而在自然暴露的葡萄中观察到较高浓度的γ-cadinene。紫外线在收获期对葡萄萜烯的排斥作用是物候学阶段特有的，在紫外线作用下，从正视到中熟，减少葡萄收获期关键萜烯的浓度，从中熟到收获期的紫外线衰减促进了α-茂烯和γ-cad烯。该研究为葡萄栽培者通过紫外线遮蔽更好地管理葡萄萜烯成分提供了信息。在从变态到收获前的紫外线衰减葡萄中观察到α-茂丁烯含量升高，而在自然暴露的葡萄中观察到较高浓度的γ-cadinene。紫外线在收获期对葡萄萜烯的排斥作用是物候学阶段特有的，在紫外线作用下，从正视到中熟，减少葡萄收获期关键萜烯的浓度，从中熟到收获期的紫外线衰减促进了α-茂烯和γ-cad烯。这项研究为葡萄栽培者通过紫外线遮挡更好地管理葡萄萜烯成分提供了信息。从中膜到中熟的紫外线膜降低了葡萄收获期关键萜烯的浓度，中熟到收获的紫外线衰减促进了α-茂丁烯和γ-卡丹烯的积累。这项研究为葡萄栽培者通过紫外线遮挡更好地管理葡萄萜烯成分提供了信息。从中膜到中熟的紫外线膜降低了葡萄收获期关键萜烯的浓度，中熟到收获的紫外线衰减促进了α-茂丁烯和γ-卡丹烯的积累。这项研究为葡萄栽培者通过紫外线遮挡更好地管理葡萄萜烯成分提供了信息。