After ageing in stainless steel tanks, barrels, etc., the wine is bottled. Legal requirements must be fulfilled in good time beforehand, i.e. the submission for the official test number (Germany) or state test number (Austria). From this point on, various changes may no longer be made. The wine has to be chemically and physically stable, which is achieved by various measures (see also under Beading). Sulphurisation takes place a long time before bottling to prevent oxidation in the bottle. To check the protein stability, a sample is heated to over 70 °Celsius for two to three hours and then checked for protein turbidity. Tartaric stability is achieved by adding metatartaric acid.