History of Wine - Production and Elaboration (2)
The fermentation process is subject to many elements, and temperature is one of them. The temperature range for fermentation to take place ranges from 5ºC to 38ºC. White wines ferment better at lower temperatures, between 8 and 14 degrees, while red wines ferment better at higher temperatures, between 25 and 30 degrees. In general, fermentation usually stops at 33ºC. The lower temperature range is preferred to preserve the freshness and fruity aromas of the wine.
In addition to the concentration of sugars, acidity and micronutrient levels, including vitamins, the aeration of the tank (oxygen supply), the infusion of fermentation-inhibiting substances such as ethanol (at levels greater than 17%), fatty acids and killer yeasts that contain polypeptides toxic to other yeasts (some of which are capable of transporting double-stranded RNA viruses), the presence of fungicides and pesticides can also prevent the fermentation process.
The fermentation process requires some essential nutrients that form an integral part of the initial mix of ingredients. The demand for certain nutrients varies depending on the fermentation phase. For example, in the phase of exponential growth, the phosphate ion (H2PO4-) is vital for the energy conversion process in cells and the growth of yeast.
Normally, wort provides sufficient phosphate for fermentation, but occasionally diammonium phosphate ((NH4) 2HPO4) is added to start the process and maintain the nitrogen and phosphate balance. In addition, other types of ammonium salts are regularly used to obtain the same result.
Since the 1950s, various fermentation processes have been used, one of the most popular of which is carbonic maceration. This specific process is carried out without pressing, at low temperatures and in a tank with a high concentration of carbon dioxide, which restricts bacterial growth and results in intense flavors and aromas in the wine, as well as fewer tannins.
However, due to the lack of aging potential, these wines are generally not suitable for long-term storage. A good example of carbonic maceration is the French Beaujolais nouveau, whose popularity has spread in recent years. The Spanish region of Tenerife is also known for its carbon-macerated red wines.
Following the carbonic maceration technique, the excess must is fermented in a conventional way and used for an alternative form of vinification.
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