The wine faults White break (gray break), black break and partly too Brown break stand bez. Causes and effects closely related. During the vegetation period takes the Rebstock over the roots also different metallic ones trace elements on. These are for example aluminum, lead. iron. copper, Silver and zinc, In the course of winemaking These are greatly reduced as primary, natural metals called substances. Incorrect or unclean processing processes can lead to increased metal contents in the wine (secondary metals).
The various causes can be corrodible cellar equipment such as reading carriages, containers, presses or other metal-containing device. The reaction of metals with the constituents of the wine produces 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 iron favors an oxidative transformation of flavorings. proteins and phenols (Tannins) in complex molecular chains that are precipitated and in the wine one cloudiness result. The wine shows a white to off-white, fine-flaky veil, called white / gray break. When in contact with air, the color changes from blue-green to blackish-green and is then called black break.
The wine taste is astringent, rough, bitter and metallic, especially at high content copper, Therefore one speaks also of metal taste or metal haze. The usual Perceptual thresholds metallic sensations are 10 mg / l for iron, 5 mg / l for zinc and 2 mg / l for copper. These wine defects can be due to great cleanliness, sulphurize and addition of Complexing agents prevented or reduced, as well as copper content by blue tinting (see beautiful ) are successfully combated.