The wine faults White break (gray break), black break and partly also Brown break stand related Causes and effects in close connection. During the growing season, the Rebstock also various metallic over the roots trace elements on. These are aluminum, for example, lead. iron. copper, Silver and zinc, In the course of winemaking these substances, called primary, natural metals, are greatly reduced. Improper or unclean processing processes can result in increased metal contents in the wine (secondary metals).
The various causes can be corrodible cellar devices such as reading carriages, containers, presses or other metal-containing devices. The reaction of metals with wine ingredients creates insoluble compounds such as iron phosphate, copper sulfide and zinc sulfide. Due to their catalytic activity, metals cause undesirable reactions with aroma changes, covering the varietal character, rapid decrease in free sulfur dioxide, early aging and unnatural color changes.
Especially the content of iron favors an oxidative conversion of flavorings. proteins and phenols (Tannins) into complex molecular chains that are precipitated and one in wine cloudiness result. The wine shows a white to gray-white, fine flaky veil, which is called white / gray break. In the event of air contact, the color changes to blue-green to blackish-green and is then referred to as black break.
The wine taste is astringent rough bitter and metallic, especially with a high content of copper, That is why one speaks of metal taste or metal cloudiness. The usual Perceptual thresholds of metallic sensations are 10 mg / l for iron, 5 mg / l for zinc and 2 mg / l for copper. These wine defects can be sulphurize and addition of Complexing agents prevented or reduced, as well as with copper content due to blue enhancement (see under beautiful ) are successfully combated.