Wine has four natural enemies: sunlight, heat, large temperature changes and oxygen. All of these factors destroy the fine aromas and balance of the wine. Accordingly, care must be taken during storage to ensure that these elements can exert as little influence as possible.
However, the wine itself already has certain ingredients that make it durable. The higher the content of these substances, the longer the wine can be stored and the higher its ageing potential. These preservability factors reflect the traditional preservation methods for food: sugaring (e.g. for jam), acidifying (e.g. for pickles), salting (e.g. for ham), smoking (e.g. for fish) and sulphurising (e.g. for dried fruit).
One of the most important factors for the longevity of a wine is its Extract - i.e. technically the Must weight (i.e. the sum of all dissolved substances in the grape must). The extract can be influenced most easily by limiting the Yield influence: The fewer grapes hanging on the vine, the higher the extract of the individual berries and the more substantial, high-quality and storable the wine. With increasing ripeness, the must weight then increases, because more and more extract substances are formed in the grape.
Sugar and Acidity occur naturally in the wine, salts in the form of Minerals also. Wines that are matured in wooden barrels are preserved by the antibacterial effect of the smoke (when the barrel is flamed, the so-called toasting) and the wood tannin. Red wines have a high degree of preservation due to the Tannin from the grape skins and seeds, red wines have an additional natural preservation factor.
Apart from these "internal" factors Sulphur (which occurs in wine in the form of sulphites, i.e. the salts of sulphurous acid) is a highly effective "external" preservative, because it binds oxygen, deprives micro-organisms such as bacteria of their basis of life and inhibits enzymes in their activity. Sulphur is added to the wine after fermentation and again before bottling; there are legal maximum values for this