IVAS 2022 banner
IVES 9 IVES Conference Series 9 IVAS 9 IVAS 2022 9 Struck flint aroma in Chardonnay wines: what causes it and how much is too much?

Struck flint aroma in Chardonnay wines: what causes it and how much is too much?

Abstract

Struck flint/struck match/gun smoke/mineral aroma is considered desirable in some styles of wines, with this character sometimes evident in wines such as Burgundian Chablis and cooler climate barrel-fermented Australian Chardonnay. Phenylmethanethiol (benzyl mercaptan) is a potent sulfur-containing volatile aroma compound and is thought to be responsible for struck flint character in wine. However, few studies targeting this character have been done. To address this, over 70 commercially available white wines, mostly Chardonnay, were chemically analysed to establish the variability of phenylmethanethiol, and the wines were assessed by a sensory panel to indicate whether there might be a transition from struck flint aroma to a less pleasant sulfurous/burnt aroma. Interestingly, another potent sulfur-containing aroma compound, 2-furylmethanethiol (furfuryl thiol), was also found in the wines and was at particularly high concentration in wines suggested as having high struck flint aroma. 2-Furylmethanethiol has previously been shown to form in white wines during alcoholic fermentation in the barrel from the furan-2-carbaldehyde (furfural) released by toasted oak staves reacting with the hydrogen sulfide produced by yeast. This survey highlighted that both phenylmethanethiol and 2-furylmethanethiol are linked to struck flint aroma but when higher levels of 2-furylmethanethiol are present, the character might tend toward sulfurous/burnt.

 There was also no information available on the effects of winemaking techniques and commonly used winemaking additives on the formation of phenylmethanethiol. Further investigations in model fermentations of its potential precursors benzaldehyde and hydrogen sulfide were conducted. Wine yeast strains that produced high concentrations of hydrogen sulfide resulted in higher concentrations of phenylmethanethiol during fermentation of a synthetic grape must and increasing concentrations of ammonia (YAN) promoted the formation of phenylmethanethiol by yeast during fermentation. Thus, different winemaking parameters could be used to modulate the concentrations of phenylmethanethiol in wine.

DOI:

Publication date: June 24, 2022

Issue: IVAS 2022

Type: Article

Authors

T. E. Siebert1*, D. Espinase Nandorfy1,2, A. G. Cordente1, L. Pisaniello1, F. T. Watson1, S. R. Barter1, D. Likos1, A. C. Kulcsar1, I. L. Francis1, and M. Z. Bekker1

1The Australian Wine Research Institute, Waite Precinct, Hartley Grove cnr Paratoo Road, Urrbrae 5064, Australia 
CASS Food Research Centre, School of Exercise and Nutrition Sciences, Deakin University 

Contact the author

Keywords

thiols, sensory, fermentation

Tags

IVAS 2022 | IVES Conference Series

Citation

Related articles…

Physiological and growth reaction of Shiraz/101-14 Mgt to row orientation and soil water status

Advanced knowledge on grapevine row orientation is required to improve establishment, management and outcomes of vineyards on terroirs with different environmental conditions (climate, soil, topography) and in view of a future change to more extreme climatic conditions. The purpose of this study was to determine the combined effect of row orientation, plant water status and ripeness level on the physiological and viticultural reaction of Shiraz/101-14 Mgt.

Effects of mechanical leafing and deficit irrigation on Cabernet Sauvignon grown in warm climate of California

San Joaquin Valley accounts for 40% of wine grape acreage and produces 70% of wine grape in California. Fruit quality is one of most important factors which impact the economical sustainability of farming wine grapes in this region. Due to the recent drought and expected labor cost increase, the wine industry is thrilled to understand how to improve fruit quality while maintaining the yield with less water and labor input. The present study aims to study the interactive effects of mechanical leafing and deficit irrigation on yield and berry compositions of Cabernet Sauvignon grown in warm climate of California.

The effects of cane girdling on berry texture properties and the concentration of some aroma compounds in three table grape cultivars

The marketability of the table grapes is highly influenced by the consumer demand; therefore the market value of the table grapes is mainly characterized by its berry size, colour, taste and texture. Girdling could cause accumulation of several components in plants above the ringing of the phloem including clusters and resulting improved maturity. The aim of the experiments was to examine the effect of girdling on berry texture characteristics and aroma concentration.

Application of a fluorescence-based method to evaluate the ripening process and quality of Pinot Blanc grape

The chemical composition of grape berries at harvest is one of the most important factors that should be considered to produce high quality wines. Among the different chemical classes which characterize the grape juice, the polyphenolic compound, such as flavonoids, contribute to the final taste and color of wines. Recently, an innovative non-destructive method, based on chlorophyll fluorescence, was developed to estimate the phenolic maturity of red grape varieties through the evaluation of anthocyanins accumulated in the berry skin. To date, only few data are available about the application of this method on white grape varieties.

Different yield regulation strategies in semi-minimal-pruned hedge (SMPH) and impact on bunch architecture

Yields in the novel viticulture training system Semi-Minimal-Pruned Hedge (SMPH) are generally higher compared to the traditional Vertical Shoot Positioning (VSP). Excessive yields have a negative impact on the vine and wine quality, which can result in substantial losses in yield in subsequent vintages (alternate bearing) or penalties in fruit quality. Therefore yield regulation is essential. The bunch architecture in SMPH differs from VSP. Generally there is a higher amount but smaller bunches with lower single berry weights in SMPH compared to VSP.