The Role of Potent Thiols in “Empyreumatic” Flint/Struck-Match/Mineral Odours in Chardonnay Wine

Abstract

Background and Aims. A wide range of Chardonnay styles exist on the market, from fruit-forward examples to wines displaying “empyreumatic” aromas such as flint, smoky, mineral, and struck-match. The thiols 2-furylmethanethiol and phenylmethanethiol have been linked to these aromas, and this study aimed to determine the contribution of these compounds to specific sensory properties in Chardonnay wines, as well as the consumer acceptance of wine displaying “empyreumatic” aromas. Methods and Results. Twenty-four Australian and New Zealand Chardonnay wines were selected for volatile analysis and quantitative sensory descriptive analysis. Consumer liking of a subset of six wines was also determined, and a further sensory study involving additions of the thiols to a base wine was conducted. Partial least squares regression showed that flint/struck-match/mineral aromas were related to 2-furylmethanethiol concentration with phenylmethanethiol less well associated. The odorant addition study confirmed that 2-furylmethanethiol directed flint/struck-match/mineral aromas and exerted strong suppression of other aromas while phenylmethanethiol played a lesser role. Consumer acceptance (n = 92) was overall lower for wines displaying high flint/struck-match/mineral aromas, although cluster analysis of the liking scores identified a sizeable consumer group (33%) who preferred wines with this attribute. Conclusions. The potent thiol 2-furylmethanethiol was indicated to be the primary contributor to flint/struck-match/mineral aromas in Chardonnay wines, with phenylmethanethiol playing a subordinate role. Significance of the Study. Increased concentration of 2-furylmethanethiol and the conferred “empyreumatic” odours should be carefully considered when producing wine styles to appeal to consumers.

Smoky Characters in Wine: Distinctive Flavor or Taint?

“…In a recent study of commercial Chardonnay wine, the contribution of potent thiols PMT and 2FMT (2-furylmethanethiol; aroma perception threshold of 0.4 ng/L in model hydroalcoholic solution) to smoke-like “empyreumatic”, struck-match aromas was assessed. The term “empyreumatic” has been used mainly in Europe to describe wines, often barrel-aged or barrel-fermented white wines, which display aromas reminiscent of smoke, gunpowder/gun flint, minerals, roasted coffee, toast, brioche, or the smoky/sulfidic aroma of a struck match . This study showed that the potent thiols, 2FMT and PMT (0.2–164.5 and 0.2–7.8 ng/L, respectively), are commonly present at concentrations of sensory significance in most commercially produced Chardonnay wines from Australia.…”

“…PMT and 2FMT were confirmed to be associated with “empyreumatic” nuances, with 2FMT in these wines most strongly related to “flint”/“struck-match”/“mineral” aroma rather than “roasted coffee” as suggested by previous reports . Notably the “flint/struck-match/mineral” note was found to be polarizing to consumer acceptance, with the largest proportion of consumers in the study responding negatively to wines high in this character . A separate study of bottle-aged Bordeaux red wine blends (matured in oak barrels prior to bottling) also found that 2FMT was associated with the “empyreumatic” attribute …”

Identification, Quantitation, and Sensory Evaluation of Thiols in Bordeaux Red Wine with Characteristic Aging Bouquet

“…With effortful manual peak picking and mass spectrum interpretation, the following previously known thiols 3-sulfanyl-2-methylpropan-1-ol, ethyl 2-sulfanylacetate, 3SH, 4MSP, 2M3FT, and FFT were found in the selected Bordeaux red wines. Certain detected thiols have been particularly associated with the positive aroma expression (3SH, 2M3FT, and FFT) of aged red wines , and empyreumatic notes (FFT) in various wines. ,, …”

“…Other subsequently identified volatile thiols such as 3-sulfanylhexan-1-ol (3SH, grapefruit odor), 3-sulfanylhexyl acetate (3SHA, passion fruit odor), 2-furfurylthiol (FFT, coffee-like odor), and 2-methyl-3-furanthiol (2M3FT, cooked meat odor) have become widely recognized among the most potent volatile aroma compounds in wine . Certain thiols were particularly linked to the empyreumatic notes in aged wines. − The identification of thiols ignited research focusing on thiol biosynthesis and fermentative biotransformation, demonstrating the significance of discovering new volatile compounds, particularly those having meaningful sensory contributions, for aroma research …”

Comparison of Techniques for the Quantitation of Reductive Aroma Compounds in White Wine: Links to Sensory Analysis and Cu Fractions

“…Glutathione, although not significant, was also found to have a large positive regression coefficient (Table S5) for overall fruit aroma, and conversely, MeSH_T, MeSH_F, GDT_H 2 S, and PMT were significantly negatively associated this term, aligning with the established literature supporting masking effects exerted by these low-molecular-weight sulfur compounds. 28 Canned corn/asparagus (calibration R 2 = 0.58, validation R 2 = 0.29) was significantly related to DMS while rubber aroma (calibration R 2 = 0.46, validation R 2 = 0.34), was significantly associated with MeSH_ST, MeSH_F, and PMT; however, these attributes were less well modeled.…”