A chemometrics approach to characterise styles of premium Chardonnay wines based on chemical and sensory attributes: a focus on drivers of positive reduction

In Chardonnay, several sulfur-containing compounds have been linked to descriptors associated with positive reduction, including 'flinty' and 'mineral'; however, the contribution of other volatiles, and the differentiation between 'flinty' and 'mineral' remains elusive. The aroma and sensory profiles of 12 commercial Chardonnay wines were characterised to pinpoint chemical drivers of 'flinty' and 'mineral' descriptors. Multivariate analyses showed that the wines varied greatly in their chemical and sensorial characteristics, with distinct groupings of similar wines. 'Flinty/gunflint' and 'mineral' descriptors were not correlated. Instead, 'flinty/gunflint' and 'onion/garlic' were highly correlated and associated with phenylmethanethiol (PMT), carbon disulfide (CS₂), ethanethiol (EtSH), methanethiol (MeSH), methionol, and 3-sulfanylhexan-1-ol (3SH). High levels of 'flinty/gunflint' also resulted in low perceptible fruitiness. To contrast, 'mineral' (nose) and 'minerally' (palate) were highly correlated and associated with benzothiazole (BT). Overall, 'flinty' and 'mineral' appear to be two distinct forms of positive reduction, and fruity attributes are masked in 'flinty/gunflint' styles.