Identification and quantitative analysis of 2-methyl-4-propyl-1,3-oxathiane in wine

Abstract

On the basis of the chemistry of wine and the co-occurrence of 3-sulfanylhexan-1-ol (3-SH) and acetaldehyde, we investigated the existence of 2-methyl-4-propyl-1,3-oxathiane (1) and identified the presence of a single detectable geometric isomer, cis-1, in wines for the first time. A stable isotope dilution assay (SIDA) using headspace-solid-phase microextraction (HS-SPME) and gas chromatography-mass spectrometry (GC-MS) was developed and validated, and used to quantitate cis-1 in a survey of wines, revealing a range from undetectable (limit of detection = 2.6 ng/L) to 460 ng/L. The odor detection threshold of 1 (using a standard comprising 85% cis-1 and 15% trans-1) in neutral white wine was determined to be 7.1 μg/L. Despite cis-1 not appearing above the determined sensory threshold in the studied wines, the findings demonstrated the presence of a new volatile sulfur compound with a strong correlation to 3-SH concentration ( r = 0.72), showing that cis-1 has potential implications for the fate of the important wine aroma compound 3-SH.