Investigating pine factor in wine flavour

The potential influence of pine and cypress windbreaks on wine flavour is under investigation.

The pine and cypress study is part of a much broader four-year Wine Australia-funded research project, being undertaken at The Australian Wine Research Institute (AWRI), titled Identification and origin of volatile compounds responsible for important wine sensory attributes.

Project leader Dr Leigh Francis said volatile chemical compounds are responsible for many important sensory characteristics in wine and influence the quality and value of a wine in the eyes of winemakers and consumers.

While many sensory attributes of wines have a known cause, some major flavour characteristics of wines – and/or the mechanisms that control their levels in grapes and wine – are not well known, such as ‘green’ flavour in red wines or the ‘stone fruit’ or ‘tropical fruit’ flavours in white wines.

Eventually, the tools created from this project might allow grapegrowers and winemakers to tailor wine style by understanding the behaviour of certain compounds through the grapegrowing and winemaking process.

‘Research in this area has several components, with flavour chemist Dr Dimitra Capone acting as the main investigator for each aspect. Part of it is identifying what exactly winemakers and consumers identify as “green” characteristics in wine’, Dr Francis said.

‘We’re also looking at the factors that influence the “green” concentrations in wines.’

As part of the project, the AWRI research team is looking at the role grape leaves and stems have in contributing ‘green’ characters to Shiraz. Wine has been made using winemaking methods to assess each of the grape bunch components, separated into five distinct treatments – just berries; berries and grape leaves; berries and stems; berries and petioles; and crushed and pressed berries.

Chemical analysis of known grassy/green compounds showed differences across the treatments, with the wines made from the stems and the leaves treatments having higher levels of ‘green’ compounds. Sensory analysis is due to take place in August.

The team is also investigating the influence of pine and cypress windbreaks – looking at both volatile absorption via the vine canopy and the presence of pine needles and leaves in harvested grapes.

Dr Francis said chemical analysis of grape berries and leaves from two vineyards has been conducted – a Pinot Noir vineyard in the Adelaide Hills bordered by a windbreak of Pinus radiata and another in the Yarra Valley bordered by cypress.

‘We also have air sampling units and volatile traps in the vineyard to try and identify what level of aerial absorption might be occurring. This is combined with sampling of grape leaves, berries and pine needles’, he said.

Dr Francis said the compounds that contribute to the aromas of pine and cypress trees were known, including the monoterpenes alpha- and beta-pinene.

‘Interestingly the pattern of volatile compounds in pine trees is similar to that found in hops used to flavour beer and in citrus peel’, he said.

‘There is plenty to learn about the sensory significance of these compounds in wine, and what factors influence their levels in wine.’