terclim by ICS banner
IVES 9 IVES Conference Series 9 ‘TROPICAL’ POLYFUNCTIONAL THIOLS AND THEIR ROLE IN AUSTRALIAN RED WINES

‘TROPICAL’ POLYFUNCTIONAL THIOLS AND THEIR ROLE IN AUSTRALIAN RED WINES

Abstract

Following anecdotal evidence of unwanted ‘tropical’ character in red wines resulting from vineyard interventions and a subsequent yeast trial observing higher ‘red fruit’ character correlated with higher thiol concentrations, the role of polyfunctional thiols in commercial Australian red wines was investigated.

First, trials into the known tropical thiol modulation technique of foliar applications of sulfur and urea were conducted in parallel on Chardonnay and Shiraz.1 The Chardonnay wines showed expected results with elevated concentrations of 3-sulfanylhexanol (3-SH) and 3-sulfanylhexyl acetate (3-SHA), whereas the Shiraz wines lacked 3-SHA. Furthermore, the Shiraz wines were described as ‘drain’ (known as ‘reductive’ aroma character) during sensory evaluation although they did not contain thiols traditionally associated with ‘reductive’ thiols (H2S, methanethiol etc.).

Secondly, a survey of over 100 commercial Australian red wines across 10 different varieties supported the outcome of the foliar application trial.2 While all red wines contained 3-SH above the sensory detection threshold (60 ng/L, aqueous ethanol), no wines were observed to contain detectable concentrations of 3-SHA. As such, the acetylation of 3-SH to 3-SHA in red wine fermentations appears to be extremely limited.

Lastly, 3-SH and/or 3-SHA were spiked into four different varieties of red wine to understand the impact on sensory attributes.2 Traditionally lighter varieties (Pinot Noir and Grenache) had increased ‘red fruit’ and ‘lolly’ ratings at low concentrations of 3-SH and 3-SHA but changed to ‘tropical’ at higher concentrations. For Cabernet Sauvignon, 3-SH and 3-SHA additions resulted in increases to ‘blackcurrant’ and ‘tropical’ attributes, whereas Shiraz additions of 3-SH resulted in ‘sweaty’ and ‘tropical’ descriptors.

The ‘tropical’ thiol, 3-SH, was ubiquitous in Australian red wines although the acetylation to 3-SHA was not commonly observed. The impact of these thiols in red wines differed by variety, and their presence was increased by vineyard foliar application treatments. As such, vineyard management practises might hold the key to avoiding undesirable expressions of ‘tropical’ characters in red wine.

 

1. Cordente, A. G.; Curtin, C. D.; Solomon, M.; Kulcsar, A. C.; Watson, F.; Pisaniello, L.; Schmidt, S. A.; Espinase Nandorfy, D. Modulation of volatile thiol release during fermentation of red musts by wine yeast. Processes 2022, 10 (3), 502.
2. Hixson, J.; Bilogrevic, E.; Capone, D.; Nandorfy, D. E.; Francis, L.; Petrie, P.; Solomon, M.; Krstic, M. AWRI report: Enhancing tropical fruit flavour in Chardonnay and Shiraz through foliar nutrient sprays. Wine & Vitic. J. 2020, 35 (3), 30-33. 
3. Siebert, T.; Francis, L.; Pisaniello, L.; Melzer, S.; Bey, L.; Watson, F.; Espinase Nandorfy, D.; Cordente, T. Do varietal thiols matter in red wine? AWRI Tech. Rev. 2019, 243, 10-15.

DOI:

Publication date: February 9, 2024

Issue: OENO Macrowine 2023

Type: Article

Authors

Tracey Siebert1, Mark Solomon1, Lisa Pisaniello1, Damian Espinase Nandorfy1,2, Eleanor Bilogrevic1, Flynn Wat-Son1, Toni Cordente1, Leigh Francis1, Josh Hixson1

1. The Australian Wine Research Institute, Waite Precinct, Hartley Grove cnr Paratoo Road, Urrbrae 5064, Australia.
2. CASS Food Research Centre, School of Exercise and Nutrition Sciences, Deakin University, 221 Burwood Highway, Burwood, VIC, 3125, Australia.

Contact the author*

Keywords

red wine, ‘tropical’ aroma, thiols, sensory

Tags

IVES Conference Series | oeno macrowine 2023 | oeno-macrowine

Citation

Related articles…

THE POTENTIAL USE OF SOLUBLE POLYSACCHARIDES TO PREVENT THE OXIDATION OF ROSÉ WINES

Lately, rosé wine is rapidly increasing its popularity worldwide. Short-time macerations with the red skin of the grapes cause the partial extraction of anthocyanins, which are responsible for the pinki-sh-salmon hue of rosé wines. However, the low quantity of tannins (antioxidants) and richness in phenolic acids, which can be easily oxidized into yellowish pigments, tend to predispose rosé wines to an undesirable browning. Although the use of SO₂ for the prevention of oxidation is highly extended, this practice is expected to be reduced. Therefore, the search for alternative oenological adjuvants that prevent the oxidation and browning of rosé wines is highly desired.

Read More

YEAST LEES OBTAINED AFTER STARMERELLA BACILLARIS FERMENTATION AS A SOURCE OF POTENTIAL COMPOUNDS TO IMPROVE SUSTAINABILITY IN WINE- MAKING

The yeast residue left over after wine-making, known as wine yeast lees, is a source of various compounds that are of interest for wine and food industry. In winemaking, yeast-derived glycocompounds and proteins represent an example of circular economy approach since they have been proven to reduce the need for bentonite and animal-based fining agents. This leads to a reduced environmental impact in the stabilization and fining processes in winemaking. (de Iseppi et al., 2020, 2021).

Read More

Grouping Vitis vinifera grapevine varieties based on their aromatic composition

Climate change is likely to impact wine typicity across the globe, raising concerns in wine regions historically renowned for the quality of their terroir1. Amongst several changes in viticultural practices, replacing some of the planting material (i.e. clones, rootstocks and cultivars) is thought to be one of the most promising potential levers to be used for adapting to climate change. But the change of cultivars also involves the issue of protecting the region’s wine typicity. In Bordeaux (France), extensive research has been conducted on identifying meridional varieties that could be good candidates to help guard against the effects of climate change2 while less research has been done concerning their impacts on Bordeaux wine typicity.

Read More

VOLTAMETRIC PROFILING OF RED WINE COMPOSITION DURING MACERATION: A STUDY ON FOUR GRAPE VARIETIES

During red wine vinification, maceration allows the must, and consequently the wine, to be enriched with several compounds that contribute to the creation of the typical organoleptic characteristics of red wines. Among these, extraction of polyphenols (PPs) during maceration is a major process of enological interest.
The purpose of this study was the evaluate the suitability of a rapid analytical approach based in linear sweep voltammetry to monitor PPs extraction during vinification.

Read More

PHOTO OXIDATION OF LUGANA WINES: INFLUENCE OF YEASTS AND RESIDUAL NITROGEN ON VSCS PROFILE

Lugana wines are made from Turbiana grapes. In recent times, many white and rosé wines are bottled and stored in flint glass bottles because of commercial appeal. However, this practice could worsen the aroma profile of the wine, especially as regards the development of volatile sulfur compounds (VSCs). This study aims to investigate the consequences of exposure to light in flint bottles on VSCs profile of Lugana wines fermented with two different yeasts and with different post-fermentation residual nitrogen.

Read More