White wine is the product of the fermentation of pure grape juice obtained from grapes by extraction from grapes. Macerations of the skins should be avoided and the must should be clarified by setting. One distinguishes two basic types, the dry, white wines and the sweet, white wines of variable sugar content.白葡萄酒是從葡萄中提取純葡萄汁發(fā)酵得到的產(chǎn)品。避免葡萄皮的浸漬，葡萄汁通過沉淀澄清。人們把葡萄酒分成兩種基本的類型，一種是干白葡萄酒，另一種是含糖量不同的甜白葡萄酒。

   Extraction of the juice should be done rapidly to avoid oxidation and maceration. It consists of the following operation.提取葡萄汁應當迅速，避免氧化和浸漬。它包括以下操作。

(1)    Crushing. This breaks the skins and permits the juice to run of the pump. Fragmentation and grinding of the berries should be avoided because they result in the formation of larger amounts of sediments.破碎：這是打碎葡萄皮，允許果汁可以泵送。應當避免碎裂和研磨漿果，因為這樣會導致形成大量的沉淀。

(2)    Draining. This can be static when the juice runs naturally from the crushed grapes. Generally one prefers dynamic drainage by means of vibrating screens or turning movements which accelerate drainage of the must and prevent oxidation.流出：這可以是靜態(tài)的，讓果汁從破碎的葡萄中自然流出。通常更喜歡動力的流出，通過振動篩或者旋轉運動，可以加速果汁的流出避免氧化。

(3)    Pressing. This permits extraction of the must remaining in the pulp. Vertical presses yield juice with little sediment because it has been filtered across a cake of pulp. But the system requires several successive pressings after crumbing and turning over of pulp. This is a lengthy operation and may lead to oxidation. Pneumatic presses permits a less damaging extraction, with better distribution, and better maintainance of the intergrity of the grape. With horizontal presses in which the pressure is not as high, the operation is more readily automated.壓榨：這是允許葡萄汁在泵中運行。垂直壓榨得到的果汁只有少量的沉淀，因為它經(jīng)過了果肉濾餅的過濾。但是系統(tǒng)要求果肉破碎后要有幾個連續(xù)的壓榨。這是一個耗時的過程，還有可能導致氧化。氣力壓榨可以減小危險提取，更好的收率，更好得保持葡萄的完整性。水平壓榨壓力不是很高，操作更容易自動化。

(4)    Clarification. This consists in the removal of insoluble particles suspended in the must. Clarification can be carried out by filtration, centrifugation, or more commonly by setting and decantation. Musts rich in sediment produce crude wines with a herbaceous taste. The presence of insoluble particles modify the constitution of the wines. Clarification is often carried out together with the addition of pectic enzymes to the must. The must contain colloidal material whose spontaneous hydrolysis by the enzymes of the grape can be accelerated by the addition of commercial enzyme preparations. Industrial pectic enzyme preparations may also contain cellulase, hemicallulase, xylanase, and protease. These enzymes catalyze the hydrolysis of plant cell wall materials to soluble compounds such as galactose, mannose, arabinose and methnol. The use of pectic enzymes in crushed grapes permits faster extraction of a larger volume of must.  澄清：這是除去懸浮在果肉中的不溶解的顆粒。澄清的完成通過過濾、離心、更普通的是沉淀和轉移。沉淀多的葡萄汁加工的葡萄原酒含有一種生青味。不溶解顆粒的存在會改變了葡萄酒的成分。澄清通常和往果汁中添加果膠酶同時進行。果汁含有膠狀物質，它可以依靠自身的酶水解，但添加商業(yè)的酶制劑可以加速這一過程。工業(yè)的果膠酶制劑可能含有纖維素酶、半纖維素酶、木聚糖酶和蛋白酶。這些酶促進植物細胞壁成分的水解成可溶解的混合物，如半乳糖、甘露糖、阿拉伯糖和甲醇。Treatment with bentonite is used to remove the proteins of the must and to prevent after-precipition that is sometimes called “protein floc”. Bentonite is an adsorbing clay. It is usually added before the fermentation to the clarified must at a rate of 60-100g/hl. After the fermentation it sediments without significantly increasing the volume of lees. This treatment also gives the wine a certain aromatic cleanness. 皂土用于除去果汁中的蛋白質防止后沉淀，它有時被稱為“蛋白絮凝劑”。皂土是一種吸附粘土。它通常在發(fā)酵前添加到澄清的果汁中，添加量60-100g/hl。發(fā)酵后它的沉淀不會明顯的增加酒渣的體積。

(5)    Fermentation. The clarified must is stored in casks or more often in tanks. Fermentation is carried out anaerobically at a temperature below 20℃. The fermentation is considered complete when the residual sugar is less than 2g/L. The this point SO₂ should be added at 6-8g/hl and the wine should be clarified as quickly as possible by filtration or centrifugation. Prolonged storage on the yeast containing lees can cause the development of sulfhydryl compounds of disagreeable odor. If a malo-lactic fermentation is desired, the wine remains on the lees without sulfating until the mali-lactic fermentation has taken place. The wine is then sulfited and filtered. Among the sweet white wine one distinguishes often the semi-dry wines, mellow wines, and sweet wines without a proper range of residual sugars for each types. 發(fā)酵：澄清的果汁貯存在木桶中，更多是在罐中。發(fā)酵完成是在溫度低于20℃厭氧條件下。當殘余糖分少于2g/L我們認為發(fā)酵完成。這個時候應當添加SO₂6-8g/hl，葡萄酒應當盡快的澄清（過濾或離心）。延長酒泥中酵母的保留時間，可以增加巰基化合物，帶來不愉快的氣味。如果需要進行蘋果酸-乳酸發(fā)酵，沉淀物上的酒體不需要硫化處理，直到完成蘋果酸-乳酸發(fā)酵。葡萄酒硫化、過濾。在甜白葡萄酒中一個區(qū)別于半干、半甜的是，甜葡萄酒沒有一個確定的殘?zhí)欠秶��?/SPAN>