摘 要：
【目的】针对我国东部葡萄酒产区在酿酒葡萄成熟期降雨过多导致香气品质下降的问题,探究避雨栽培对‘赤霞珠’葡萄果实绿叶挥发性组分及其衍生酯类积累的影响,以期为该项措施的应用提供依据。【方法】以2012和2013年采自北京密云地区张裕爱斐堡酒庄葡萄园的‘赤霞珠’(Vitis vinifera‘Cabernet Sauvignon’)果实为试材,采用固相微萃取-气相色谱与质谱联用技术,分析游离态和糖苷结合态香气物质的种类和含量,比较避雨栽培和露地模式下果实成熟过程中绿叶挥发性组分积累规律的异同。【结果】避雨栽培下葡萄果实周围的太阳总辐射和光合有效辐射下降约20%,紫外辐射下降约40%。在2012年避雨栽培的成熟果实可溶性固形物含量明显升高,而在2013年2种栽培模式生产的果实可溶性固形物和可滴定酸含量无显著差异。综合2 a(年)数据,避雨栽培降低了成熟果实有"青草"气味的游离态脂肪醇、反式-2-己烯醛和反式-2-己烯酸的含量,而提高了结合态反式-2-己烯醇、己醇和反式-3-己烯醇等、以及游离态和结合态己醛和己酸的含量。此外,避雨栽培也显著增加果实中有"果香"气味的游离态和结合态酯类化合物含量,如乙酸己酯、辛酸乙酯和顺式-乙酸-3-己烯酯等。相对于2013年,避雨栽培的这些影响在降雨量相对较多的2012年更为显著。【结论】避雨栽培可以减弱葡萄的绿叶气味,提升果实和葡萄酒潜在果香品质,尤其在降雨相对较多的年份,可有效地缓解果实品质的下降。
译 名：
Effects of rain-shelter cultivation on green leaf volatiles of 'Cabernet Sauvignon' grape
作 者：
FU Yaqun;GAO Yuan;MENG Nan;PAN Qiuhong;Center for Viticulture and Enology, College of Food Science and Nutritional Engineering, China Agricultural University;Key Laboratory of Viticulture and Enology, Ministry of Agriculture;
单 位：
Center for Viticulture and Enology, College of Food Science and Nutritional Engineering, China Agricultural University%Key Laboratory of Viticulture and Enology, Ministry of Agriculture
关键词：
Grape berries(Vitis vinifera L.'Cabernet Sauvignon');;Green leaf volatiles;;Rain-shelter cultivation
摘 要：
【Objective】Volatile compounds are of importance to the quality of grape berries and wines.They largely determine the aromatic quality and variety characteristics. Green leaf volatiles(GLVs) are short-chain acylic aldehydes, alcohols and esters produced by plants via enzymatic metabolism of polyunsaturated fatty acids. These compounds, which are normally the most abundant volatiles in grape berries,not only endow grape berry and wine with‘leaves',‘grass' or‘fresh vegetative'odor, but also provide the direct precursors for the synthesis of hexyl acetate. Hexyl acetate in wines is found to be grape dependent and contribute to fruity character. Different from free-form volatiles, glycosidically bound GLVs in grape berry are rarely paid attention on possibly because they don't have direct contribution to the aroma attributors. But they possess potential importance in grape varieties used for making wine. In the wineproducing regions of east China, the quality of berries and wines are largely interfered with excessive rainfall during grape maturation season. To minimize the declining of berry aroma quality, rain-shelter measurement has been implemented. The present study aimed at evaluating the effects of rain shelter on theaccumulation of GLVs and the lipid-derived esters in developing‘Cabernet Sauvignon'grape berries.The research outcome will provide theoretical basis for this cultivation mode application.【Methods】Theexperiment was carried out in a‘Cabernet Sauvignon'(Vitis vinifera L.) vineyard of the Chateau ChangyuAfip Global(44°30′N, 116°80′E), located in Miyun County of Beijing, in 2012 and 2013 vintages. Theown-rooted grapevines were planted in south-north row orientation with 1.0 m × 2.5 m spacing, and theywere trained into a sloping trunk with a horizontal cordon. The rain-shelter roof was set up on the 14 thday after flowering(DAF, 14 th June) in 2012 and 36 DAF(13 th July) in 2013. A randomized block designwas adopted, and a total of six blocks were chosen to create three rain-shelter cultivation replicates andthree open-field cultivation replicates. Each block comprised 40 grapevines. To understand the change inmicroclimate around the grapevines under the rain-shelter and in the open field, dataloggers and probeswere installed around the clusters for collecting microclimatic data. Grapes were sampled at 20, 37, 50,64, 71, 78, 87, 97, 112, 125 and 135 DAF for the 2012 vintage and at 14, 28, 41, 57, 67, 78, 97, 112 and124 DAF for the 2013 vintage. The harvested samples were placed in plastic bags and quickly transportedto the laboratory. About 100 fresh berries per replicate were used for the determination of total soluble sol-ids and titratable acids. The remaining samples were immediately frozen in liquid nitrogen and stored at-80°C. Free-form volatile compounds were extracted from fruits by using headspace solid phase micro-ex-traction(HS-SPME) method, and glycosidically bound volatiles were separated through a Cleanert PEP-SPE column, followed by the hydrolysis by glycosidase AR2000 and the adsorption of HS-SPME. Thequalitative and quantitative analyses of free and glycosidically bound volatiles were performed via thetechnology of gas chromatography-mass spectrometry.【Results】Both total solar radiation and photosyn-thetically active radiation reaching the grape clusters were reduced by about 20%, and ultraviolet radia-tion was decreased by 40% under the rain shelter. With the growth and development of grapes, total solu-ble solids increased and titratable acids declined especially after veraison. The rain-shelter application,compared with the open-field cultivation, resulted in a significant increase in total soluble solid content inthe 2012 vintage, but no significant difference in both total soluble solids and titratable acids in the 2013 vintage. Combined the two-year data, free-form straight-chain aliphatic alcohols, including(E)-2-hexe-nal and(E)-hexenoic acid with green leaf odor, under the open-field cultivation was higher than those un-der the rain-shelter cultivation. However, rain-shelter application raised the levels of glycosidicallybound straight-chain aliphatic alcohols, such as(E)-2-hexen-1-ol, hexanol and(E)-3-hexen-1-ol, aswell as free and glycosidically bound hexenal and hexenoic acid. Additionally, free and bound straight-chain aliphatic esters(fruity aroma) were increased in the rain-shelter grape, including hexyl acetate, eth-yl octanoate, and(Z)-3-hexen-1-ol acetate. The two-way analysis of variance indicated that 22 free-form and 15 glycosidically bound-form volatiles dramatically differed between the vintages, and 6 free-form and 4 bound-form GLV compounds varied with the cultivation treatments. F test showed that vintageinfluence was stronger than the cultivation mode. There was significant interactive effect of vintage andrain-shelter treatment on the concentrations of 6 free-form GLV compounds including(E)-2-hexenal,nonanal, decanal, 1-hexanol,(E)-2-hexenol and 1-octanol. In addition, four bound-form GLV com-pounds, decanal, 1-hexanol, 1-heptanol and 1-dodecanol, also exhibited a significant difference. Therewas difference in the total rainfall(524.2 mm and 465.6 mm) existed in the whole period of berry develop-ment between 2012 and 2013 vintages. Excessive rainfall was considered to interfere with the accumula-tion of green leaf volatiles, but the rain-shelter application could effectively avoid the effect, which wasdisplayed in the 2012 vintage with more rainfall compared to the 2013 vintage.【Conclusion】Comparedwith the open-field cultivation, rain-shelter cultivation in this study greatly lessened the green leaf odorof grape berries and consequently improve fruity aroma of grapes and wines. The improvement in total soluble solids and fruity aroma under the rain-shelter was significant in the vintage that received higher rainfall. Based on our results, it is concluded that simple rain-shelter cultivation can effectively relieve the deterioration of berry quality especially in the vintage with much rainfall.
