Basically, without yeast which creates the alcohol, there would be no wine, at least not with an alcoholic base. The progress of fermentation can be monitored or controlled in several ways. The most simple method is to observe the activity in the fermentation vessel. Sometimes in a laboratory setting, fermentation is often followed by weighing the fermentation vessel at various intervals which results in a record of the weight of carbon dioxide gas lost and exactly how much sugar remains in the vessel. The most popular form of control is a measurement of the density of a sample of the fermenting juice which can be accomplished by using a hydrometer which measures the remaining sugar's percentage in weight.

As to the taste of wine that results form this complex series of chemical manipulations by a chemist or fermentation specialist, the time required for complete fermentation of grape juice, either white or red, varies greatly. First of all, the temperature maintained in the fermenting mass is the main factor which affects the duration of fermentation, as well as the overall taste or character of the finished product. The second factor has much to do with the initial sugar concentration in the mass, the type of yeast used and the quantity of micro-nutrients in the juice itself. Generally speaking, red wine fermentation is complete within four to seven days; white wine, which is often fermented at much lower...

In most commercial wineries, fermentation is often deliberately slowed down so that a single fermentation vessel, such as an oak cask, may be used twice or even three times per wine-producing season. Of course, these processes account for the fact that various types of wine taste different. For example, in the making of certain styles of wine, such as port and certain types of liqueurs, the fermentation process may be stopped at specific points in time by the addition of alcohol, usually grape spirits, which has the effect of increasing the alcoholic content.
Not surprisingly, the overall character or taste of various types of wine (and for that matter, certain types of beer) can be determined by making and storing the wine in different types of containers. As to the types of fermentation processes which truly affect the taste of various wines, some include barrel fermentation, carbonic maceration, rose wine-making, fermentation in a bottle, malolactic fermentation and secondary fermentation.

Bibliography

History of Wine." Ewineplanet.com. Internet. 2007. Retrieved at http://ewineplanet.

Com/menu.asp?id=1.