In the course of winemaking in red as in white, the pH often varies. The reason? The change in equilibrium constants due to ethanol, the decrease in acid salt levels, the consumption of malic acid and amino acids, the formation of succinic acid and the chemical reaction that tartaric acid undergoes. Wine is in fact an acid-base solution containing weak acids AH, which release hydrogen ions H+ in the presence of their salts A- (which accept protons by acting as strong bases). Acids therefore tend to form salts, with strong acids dominating. However, appreciable variations in pH are countered by the so-called 'buffering capacity', which determines the chemical-physical, microbiological and organoleptic stability of wine, and which - the higher it is - makes it more difficult to alter the pH of wine.