The term for alcoholic fermentation in the winemaking previously referred to the apparent "cooking" or "foaming" in the grape, Fermentation is the microbial degradation of organic matter without the inclusion of external electron acceptors such as oxygen ( anaerobically ) understood for the purpose of energy production. Organic substances can also be broken down with the inclusion of oxygen ( aerobic ) occur. For example, the acetic fermentation Oxygen is consumed, which is why it is not a fermentation in the scientific sense as described at the beginning. The term fermentation however, in German is an umbrella term for aerobic and anaerobic processes. This often leads to confusion because "fermentation" is used for alcoholic fermentation in other languages or because there is no separate term for it.
The process was long thought to be natural decay. The influence of air (even when oxygen was already discovered) was ignored. This is why the processes involved in converting must into wine, seasoning into beer and wine into vinegar called fermentation. The participation of microorganisms was by Louis Pasteur (1822-1895) recognized in 1857. Fermentation occurs everywhere spontaneous, where at an optimal temperature between 18 and 27 ° C yeast come into contact with aqueous sugar solutions. These are usually fruit juices, but other substances dissolved or added to water, such as cereals (barley, wheat, corn, rice), can also be used in the production of beer or other sugary substances such as potatoes.
The fermentation at Wine is mostly temperature controlled in stainless steel tanks In larger companies this is also done using computers. But also one barrel fermentation is used by many producers. For an optimal fermentation is a corresponding one beforehand must treatment Fermentation is the enzymatic breakdown of organic matter in anaerobic Environment, that is, in the absence of oxygen, If there is a higher concentration glucose (Dextrose) in grape can also in the presence of oxygen, ie in aerobic environment alcohol be formed. According to the English biochemist Herbert Grace Crabtree, this is also called Crabtree effect (or pasteur effect). An aerobic environment with oxidative Processes is also like in the production of certain wines port wine and sherry common.
The yeasts play a crucial role in fermentation. After this Press multiply in grape frenziedly fast through sprout and division. Towards the end there are 50 to 200 billion yeast cells per liter of wine. The biochemical processes are contained in the yeast enzymes controlled; for fermentation is the Zymase complex responsible. Natural or wild yeasts are widely available in the vineyard and elsewhere (air) and reach the cellar with the grapes. Through this, the fermentation can also be triggered completely independently, which was previously the custom. In this case one speaks of spontaneous fermentation, However, this is far more difficult to control, but is becoming increasingly particularly associated with Organic viticulture in the generation of Biowein prefers.
Mainly, however, pure breeding fermentation is still used, which is initiated using pure breeding yeasts (culture yeasts). These guarantee a quick, uncomplicated...