Accurate quantitative determination of the total amounts of Strecker aldehydes contained in wine. Assessment of their presence in table wines

Abstract

Strecker aldehydes (SAs) are key determinants of wine shelf-life and can be present in unoxidized wines in odorless forms, such as hydroxyalkylsulfonates, imines or acetals. A robust and accurate method for the determination of total forms of SAs, based on the classical derivatization with O-(2,3,4,5,6-pentafluorobenzyl)hydroxylamine (PFBHA) and in the selective solid phase extraction of derivatives has been optimized and validated. Matrix effects have been solved by the use of adequate internal standards and by large-enough equilibration times under anoxic conditions. Method figures of merit are highly satisfactory in terms of detection limits (<0.1 μg/L), linearity (R² > 0.997), reproducibility (5-13%) and recoveries (RSDs, between 2 and 10%, for 3-methylbutanal, 14%). The analysis of total SAs in 108 Spanish wines revealed that between 52% and 70% of unoxidized red wines and likely a similar fraction of white wines, contain levels of SAs high enough to cause oxidative aromas if bound forms of SAs cleave.

Keywords: 2-methylbutanal (Pubchem CID: 7284); 3-methylbutanal (Pubchem CID: 11552); Bound forms; Isobutyraldehyde (Pubchem CID: 6561); Longevity; Methional; Methional (Pubchem CID: 18635); Off-odors; Oxidation; Phenylacetaldehyde; Phenylacetaldehyde (Pubchem CID: 998); Sulfite.