Volatile compound insights: Flavour attributes of current and future commercial significance to growers and winemakers
Summary
Objective
The project will address the identity, formation, and chemical changes of flavour compounds that have been prioritised with sector input. Known flavour pain points for most sections of the industry, such as ‘reductive’ and ‘vegetal’ aromas, will be investigated together with insights on under-studied positive characteristics (e.g. caramel, red berry and barrel-fermentation-related flavours) to provide a portfolio that spans compound discovery through to sector-led applications. For example, recent work has shown high concentrations of phenylmethanethiol (BnSH) in Australian Chardonnay wines, related to ‘flint/struck match’ aroma. Research will determine how this compound is formed, the potential role of barrel maturation and avenues for its control. Compounds will be investigated during fermentation and following short-term storage where chemical/biochemical transformations and reaction kinetics will be studied with an aim to increase accessibility of desirable characters to a greater proportion of the sector.
Previously identified compounds responsible for ‘jammy’, or ‘raisin’ in Shiraz, and compounds providing ‘peach’ character in white wines will be further investigated to understand how they evolve in different varieties or change during fermentation or storage.
The project will provide methods to measure compounds and knowledge of their sensory significance. It will study production options that affect the concentration of the aroma compounds, will provide tools for evaluation of trials conducted by wine companies, and measures to be applied to future viticultural and winemaking research studies.
Background
Understanding the formation and fate of key volatile compounds is a core capability that requires continuation in our sector, as these compounds provide researchers and producers with quality targets for improvements in vineyard and winemaking practices. Volatiles contribute specific varietal and regional characters and contribute greatly to the overall in-mouth sensory experience. The volatiles of wine can be the mark of its quality for a consumer when drinking or the basis of its rejection and are influenced at every stage of handling or processing. At the core of an innovative sector is the ability to understand and measure key volatiles, while developing practices to influence or control flavours associated with wine quality and style. For several specific sensory attributes that drive consumer preference the directing compounds are not known. There are serious gaps in knowledge regarding the origin of wine flavours, including their formation and changes that occur over time; the sensory effect of specific compounds; and how a compound interacts with other wine compounds to affect the nature and intensity of perceived important flavour attributes. For many known flavour compounds, information regarding the concentration ranges that give desirable or undesirable flavour qualities and the ability to quantify their concentration in wines and grapes is also lacking.
This project builds on findings from previous research in AWRI 1701-3.1.1 (Identification and control of volatile compounds responsible for important sensory attributes).