关于一颗葡萄

葡萄汁转化为葡萄酒的过程就是一部完整的葡萄与酵母的生命史。

关于葡萄

每颗葡萄的末端都有一个茎stem或梗pedicel，将其与葡萄藤连接起来。梗是一种阀门，养分和水通过它为葡萄提供营养。

就像我们自己的身体一样，植物需要将营养物质输送到其各个组成部分。我们体内的主要营养载体是通过静脉、动脉和毛细血管组成的血管系统循环的血液。

在植物中，两个维管系统穿过梗，两者都由成群的细胞组成，形成称为木质部和韧皮部的微小管状结构。一根管子通常位于另一根管子的内部，形成管套管系统。

木质部xylem和韧皮部phloem在维管系统中充当筛子，控制蛋白质、糖和激素等分子进出葡萄。

其中木质部是内管，负责运输水、生长激素、矿物质和来自根系统的营养物质，并为葡萄藤提供营养。

木质部在葡萄的早期发育过程中发挥着重要作用，但随着葡萄的继续成熟，它的重要性就消失了。葡萄发育的后期阶段被称为转色期（成熟的开始），其开始通常是通过木质部维管系统的关闭来宣布的。

韧皮部负责运输蔗糖和藤蔓叶区光合作用的产物。在转色期之前，韧皮部活动较弱，一旦转色期开始，韧皮部才会发挥作用。

木质部和韧皮部共同调节葡萄的大小和体积，从而调节其水分和糖分的含量。而葡萄中这些关键成分量对发酵至关重要，因为酿酒的核心即是糖和水转化为酒精。但由于葡萄果肉、种子和果皮的几乎所有成分都在酿酒中发挥作用，因此所有这些元素的平衡对于葡萄酒的外观、味道和感觉也至关重要。

What happens as grape juice is transformed into wine is rooted in the life histories of both grapes and yeast.

At the end of each grape there is a stem, or pedicel, that connects it to the vine. The pedicel is a kind of valve through which nutrients and water pass to provide the grape with nourishment. Like our own bodies, plants need to transport nutrients to their various constituent parts. The major nutrient carrier in our bodies is the blood that circulates through our vascular system of veins, arteries, and capillaries. In plants, two vascular systems pass through the pedicel, both made up of grouped cells that form the tiny tubelike structures called xylems and phloems. One tube typically lies inside of the other, forming a tube-within-a-tube system.

The xylem and phloem act as sieves, controlling the flow of molecules such as proteins, sugars, and hormones into and out of the grape. The xylem is the inner tube and is responsible for transport of water, growth hormones, minerals, and any nutrients that come from the root system that feeds the remainder of the vine. It plays an important role during early development of the grape, but it loses its importance as the grape continues ripening. The later stage of grape development is known to grape growers as véraison (onset of ripening), and its beginning is usually announced by the shutting down of the xylem vascular system.

The phloem is responsible for the transport of sucrose and products of photosynthesis in the leafy area of the vine. Before véraison, phloem ac- tivity is muted, but once véraison commences, the phloem comes into its own. Together, the xylem and phloem regulate the size and volume of the grapes, and hence their sugar and water content. Controlling the quanti- ties of these critical ingredients in each grape is essential in fermentation

and central to winemaking: the sugar and water are what is turned into alcohol. But since almost all the components of the grapepulp, seed, and skin have a role to play in winemaking, getting all these elements in balance is also critical to the look, taste, and feel of a wine.