A reduction of alcohol in the wine can take place by means of various physical and / or chemical processes. Especially in southern areas, this is a relatively common practice with the aim of aromatic and less alcoholic wines. The simplest and cheapest form is the addition of fruit juice or grape juice, resulting in the production of Cooler is applied, or by water (routes). A certain alcohol content can also be stopped by stopping fermentation by cooling, which is practiced especially in Italy for simple wines. The result is sweet, sparkling and low-alcohol wines. In most cases, thermal separation processes such as vacuum distillation (vacuum rectification) are used.
The boiling point of pure ethanol is about 78 ° Celsius, which is indeed in the distillation is exploited. However, this temperature would be too high for the purpose of alcohol reduction, since valuable flavorings would be lost. Therefore, this is done at a reduced pressure of 0.07 to 0.15 bar (otherwise 1 bar) in the temperature range of 30 to 60 ° Celsius to keep a material change as low as possible. The residence time and temperature should be as low as possible. Other methods include electrodialysis, High-pressure extraction, filtration (Nanofiltration, ultrafiltration), osmosis (Reverse osmosis, osmotic distillation), pervaporation and Spinning Cone Column, The specifications regarding the permitted procedures differ in the countries. In Austria, the relevant provision states that the "methods are not expressly specified but suitable methods are vacuum distillation and reverse osmosis".
For the production of alcohol-free wine is not considered as basis grape but already used fermented wine with a "normal" alcohol content between 9 and 14% vol. This must then be withdrawn in an additional step, the alcohol. So he went through the same stages of development as normal wine and contains all after the alcohol reduction flavorings, For this reason, it retains at best the character of the original wine but just with an alcohol content of only 0.5% or less, which of course, the taste changes somewhat.
Low-alcohol wine is produced either as non-alcoholic wine or by blending de-alcoholised wine with regular wine. The alcohol content must be more than 0.5%, but may not exceed 5.0% vol. Both types of wine may be used to produce unfermented sugar (ie residual sugar ) up to a maximum of 60 g / l of grape must, RTK (rectified concentrated grape must) or sugar (Beet sugar) are added. Likewise, in both the addition of carbonic acid and vegetable aromatics.
On the label this is de-alcoholized by the hints, low in alcohol or flavored declare accordingly. More details about origin (only the land of the grape harvest is allowed), varieties and vintage are not allowed. A "de-alcoholized wine" may be called "alcohol-free" as well as non-alcoholic beer, if the alcohol content is less than 0.5% vol or 4 g / l. Complete dealcoholization is not required despite the claim "non-alcoholic". The term "without alcohol" may only carry a food if the alcohol content is 0.0% vol. For wines, this may never be the case for technological reasons.
However, the residual alcohol content has, according to scientific studies, no disadvantageous, hazardous Effect on the organism, it corresponds approximately to that of various fruit juices and is even below the alcohol content of various foods such as kefir and even pastry. However, non-alcoholic wines or beers with an alcohol content of up to 0.5% may be dangerous for an alcoholic. This is not only a question of alcohol content, but also of mental health. There is no universally valid limit from which it becomes "dangerous" (see below alcoholism ).
Within the EU, wines may not exceed 20% vol alcohol content be reduced. This can only be done by separation techniques such as distillation. Spinning Cone Column and osmosis or membrane techniques like pervaporation be achieved. The method must not be used for wines, the other organoleptic Have defects. The removal of alcohol from wine must not be accompanied by a change in the sugar content in the wine grape respectively. Of course, the minimum alcohol content requirements must be met. Another but preventive application is the desiccation of grape must. The addition of water to grape must or wine (as in Overseas usual) is prohibited in the EU.
By means of appropriate preliminary tests, the "optimum alcohol content" is determined beforehand. At this level, also known as the "sweet spot", the wine reaches as perfect as possible harmony between Aroma. fruitiness and taste, A small batch of the wine with a very high alcohol content is partly dealcoholated. Then, a series of wines with gradual differences in alcohol content is created over up to ten blends in small increments from 0.1 to 0.2% vol. These will be then sensory tasted and tasted the "best" wine. Then the reduction is made to this ideal degree for the total amount.
In the research institute Geisenheim a method was developed by means of the enzyme Glucose oxidase which is present in grape must glucose in gluconic convert. Gluconic acid can be from the metabolism of yeasts not be converted into alcohol. This will be after the two scientists Herbert Grace Crabetree and Louis Pasteur (1822-1895) also as " Crabtree effect Or "Pasteur effect". Likewise also with selection of inefficient yeasts is experimented and thus purposefully wines with balanced Alcohol content generated.
Complete listings of the numerous vinification measures and cellar techniques, as well as the various wine-regulated wine, sparkling wine and distillate types are under the keyword winemaking contain. Comprehensive information on wine law is available under the keyword wine law,