Quinones as Strecker degradation reagents in wine oxidation processes

•The role of quinones in wine oxidation as Strecker degradation reagents was studied.•Phenylacetaldehyde can be formed by quinone intermediates at wine normal pH.•Caffeic acid was the phenolic compound that produced the lowest amounts of phenylacetaldehyde.•(+)-Catechin was the phenolic compound that produced the highest amounts of phenylacetaldehyde.

The Strecker aldehydes formed during the reaction between α-amino acids (phenylalanine or methionine) and either gallic acid, caffeic acid or (+)-catechin ortho-quinones were evaluated in wine-model systems. It was demonstrated that phenylacetaldehyde was formed by quinone intermediates at wine pH. The highest amounts of phenylacetaldehyde during the 10 days of experiment (69 ± 5 µg/L/day; 7x > Control) were obtained from (+) catechin, followed by gallic acid (61 ± 4 µg/L/day; 6x > Control) and caffeic acid (41 ± 4 µg/L/day; 4x > Control). The intermediate structures delivered from the reaction of ortho-quinones with α-amino acids were demonstrated by MSn.