‘意大利’葡萄延迟栽培挂树贮藏期间果实品质的变化

Studies on Quality Development of‘Italia'Grape During On-vine Storage Under Delayed Cultivation

为明确设施条件下葡萄延迟栽培果实挂树贮藏期间品质变化规律及香气成分与发育阶段间的关系,以设施栽培的‘意大利’葡萄为试材,测定果实的呼吸速率、丙二醛、色差、维生素C、可滴定酸、葡萄糖、果糖、蔗糖、挥发性组分等指标在挂树贮藏期间的变化。结果表明：‘意大利’葡萄的挂树贮藏期可分为前、中、后期,挂树前期（成熟后0-20 d）,果实的呼吸速率、丙二醛含量、单粒质量、果实表皮L＊、b＊、C＊、可溶性糖含量等有所升高,a＊的绝对值、可滴定酸及维生素C含量有所下降,挥发性成分中里那醇含量较稳定,C6化合物含量降低,醛类物质含量有所增加;挂树贮藏中期（成熟后30-60 d）,除呼吸速率、丙二醛含量、L＊值外,其他指标均表现出波动性下降的趋势,挥发性成分中里那醇含量降低,而香叶醇含量升高,醛类物质含量降低,酯类物质有所增加;挂树后期（成熟后70-80 d）,呼吸速率、丙二醛含量较高,其他指标水平较低,C6组分对香气的贡献值升高。由此可得,葡萄果实挂树初期品质性状有所升高,商品性较佳,挂树中期主要萜烯类组分对香型的贡献值出现变化,果实品质缓慢下降,为果实品质调控的关键时期,挂树后期,C6醛代谢途径有所增强,果实商品性较差。

The delayed cultivation has been used to realize the long-term supply of fresh table grapes around the world. In order to make clear the changes of grape quality and the relationship between volatile compounds and developmental stages during on-vine storage under delayed cultivation facilities,this study chose Vitis vinifera‘Italia＇as test material and measured the changes of berries respiration intensity,single berry weight,brightness L＊,brightness style a＊ and b＊,tint strength C＊,and content of MDA,titratable acid,vitamin C,soluble sugar and volatile compounds. The results indicated that on-vine storage period could be divided into three stages by physiological indexes and the principal component analysis. The initial stage started from 0 to 20 days after maturation. During this period the berries respiration intensity,single berry weight,L＊,b＊,C＊ and content of MDA,glucose,fructose and sucrose increased,while the absolute value of a＊,content of titratable acid and vitamin C decreased. As for volatile compounds,the content of linalool was stable,and C6 compounds were decreasing,but aldehydes were increasing. When grape berries developed to the middle stage（30–60 days after maturation）,the respiration intensity and content of MDA increased while other indexes like tint strength,content of soluble sugar,soluble acid and vitamin C decreased undulately. As for volatile compounds,the content of linalool decreased while geraniol increased. Esters accumulated in this stage but the content of aldehydes decreased. In the final stage（70 to 80 days after maturation）,berries respiration intensity and MDA content were high and other physiological indexes were low. As for volatile compounds,the contribution of C6 compounds to the fruit aroma increased. In conclusion,this study revealed that the grape quality was enhanced during the initial on-vine storage stage,then gradually declined in the middle stage with the contribution of major terpenes to aroma changing and lost the market value as C6 aldehydes metabolic pathway activated in the final stage. So the middle stage（30–60 days after maturation）was the key period for grape quality regulation during on-vine storage under delayed cultivation.