Changes in the Buffering Capacity of Model Solutions of 40 mMTartaric or Malic Acids in Relation to Amino Acids

Abstract

The contribution of some amino acids (<i>i.e.</i>, arginine, proline, serine, alanine, threonine) to the buffering capacity of wine using model solutions is established. Although amino acids have no buffering capacities at the pH of wine (2.9 to 4.0), they increase the buffering capacity of a 40 m<i>M</i> tartaric acid solution, even at concentrations found in champagne wines. In contrast, when they are added to a 40 m<i>M</i> malic acid solution, they induce no changes in the buffering capacity. It appears that the changes in the buffering capacity depend on the nature of the amino acid used, its concentration, and the medium used. For a 40-m<i>M</i> tartaric acid solution, additions of 400 mg/L of each amino acid increase the buffering capacity from 21% in water to 36.8% in an hydroalcoholic medium (11%, v/v).