ABOUT THE ROLE PLAYED BY THE DIFFERENT POLYPHENOLS ON OXYGEN CONSUMPTION AND ON THE ACCUMULATION OF ACETALDEHYDE ANDSTRECKER ALDEHYDES DURING WINE OXIDATION
In a previous work1, it was suggested that the different contents in delphinidin and catechin of the grapes were determinant on the O2 consumption and Strecker aldehyde (SAs) accumulation rates. Higher delphinidin seemed to be related to a faster O2 consumption and a smaller SAs accumulation rate, and the opposite was observed regarding catechin.
In the present paper, these observations were fully corroborated by adding synthetic delphinidin to a wine model containing polyphenolic fractions (PFs) extracted from garnacha and synthetic catechin to a wine model containing PF extracted from tempranillo: The delphinin-containing garnacha model consumed O₂ significantly faster and accumulated significantly smaller amounts of SAs than the original garnacha model, and the catechin-containing tempranillo model, consumed O2 significantly slower and accumulated significantly higher amounts of SAs than the original tempranillo model.
The work was further expanded by studying the effects of 8 individual polyphenols (delphinidin, malvidin, caffeic and coumaric acids, catechin, epigallocatechin, quercetin and myricetin) in normalized wine models subjected to a forced oxidation procedure on the O2 consumption rates (OCRs) and acetaldehyde and SAs accumulation rates.
Most surprisingly, all polyphenols but anthocyanins, initially slowed down OCRs observed in the plain wine model, which contained cation metals, hydrogen sulfide, cysteine and glutathione in reduced forms. Leaving aside anthocyanins, only B-ring tri-hydroxylated polyphenols were able to consume all O2 supplied. Moreover, the polyphenol determined also the fraction of ethanol oxidized to acetaldehyde. Catechin is the strongest inducer of ethanol oxidation, while delphinidin and epigallocatechin were the weakest.
Regarding SAs, the surprising finding is that, considering formation per O2 consumed, these are most efficiently formed in the basic wine model without polyphenols. Efficiency comes to a minimum with delphinidin, followed by coumaric acid and malvidin.
These set of results introduces a completely new perspective to wine oxidation kinetics and to the accumulation of aldehydes.
Funded by Spanish MICYN, PID2021-126031OB-C21
1. Bueno-Aventin, E., Escudero, A., Fernandez-Zurbano, P., & Ferreira, V. (2021). Role of Grape-Extractable Polyphenols in the Generation of Strecker Aldehydes and in the Instability of Polyfunctional Mercaptans during Model Wine Oxidation. J Agric Food Chem, 69(50), 15290-15300
Issue: OENO Macrowine 2023
Laboratorio de Análisis del Aroma y Enología -LAAE. Affiliated to Instituto Agroalimentario de Aragón (IA2) (UNIZAR-CITA). Dept. Anal. Chem., Fac. of Sciences, University of Zaragoza, 50009 Zaragoza, SPAIN
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oxidation, acetaldehyde, Strecker aldehydes, polyphenols