Investigation of 'stone fruit' aroma in Chardonnay, Viognier and botrytis Semillon wines.

Despite numerous studies, the identity of the compounds that are responsible for 'stone fruit' aroma in wine has not been conclusively established. This study focussed on wine varieties that often display peach and apricot characters, such as Chardonnay, Viognier and botrytis-affected sweet Semillon wines. Wines with high and low 'stone fruit' aroma were evaluated by gas chromatography-olfactometry-mass spectrometry (GC-O-MS) using extracts representative of the aroma of the wine in a glass. No aroma-active zone was described as 'stone fruit' aroma across all three wine varietals. However, for the individual varieties, terpenes, such as linalool and geraniol, in the Viognier wines, several esters in the Chardonnay wines, and γ-nonalactone in the botrytis Semillon were associated with 'stone fruit' aroma. Notably, this is the first study assessing the aroma profile of Viognier wine by GC-O. In addition, an extension study of Viognier grape monoterpene profiles clarified its classification as an aromatic variety.

Analysis, potency and occurrence of (Z)-6-dodeceno-γ-lactone in white wine.

(Z)-6-Dodeceno-γ-lactone is a potent aroma compound that has been little studied and its prevalence in wines is unknown. An efficient stable isotope dilution assay was developed using a simple, direct immersion solid-phase microextraction and gas chromatography-tandem mass spectrometry method suitable for routine use with a low ng/L limit of quantitation. Using this method, 99 out of 104 young white wines analysed were found to contain detectable (Z)-6-dodeceno-γ-lactone. The highest concentrations were found in Riesling and Viognier wines. (Z)-6-Dodeceno-γ-lactone was found to have an aroma detection threshold of 700 ng/L in a neutral white wine. This study established that (Z)-6-dodeceno-γ-lactone is widely present in Australia's most popular white wine varieties, but generally at concentrations below its aroma detection threshold.

Volatile Compounds Related to 'Stone Fruit' Aroma Attributes in Viognier and Chardonnay Wines.

A 'stone fruit' aroma is important in many white wine varieties and styles, but little is known about the chemical basis of this wine aroma attribute. A set of Viognier and Chardonnay wines that featured 'stone fruit' aroma attributes were selected by a panel of wine experts. The selected wines were characterized by sensory descriptive analysis and detailed volatile chemical composition analyses. This comprehensive data also allowed Viognier wine to be profiled for the first time. By partial least-squares regression, several esters and fatty acids and benzaldehyde were indicated as contributing to the 'peach' attribute; however, a reconstitution sensory study was unsuccessful in mimicking this attribute. A mixture of γ-lactones, monoterpenes, and aldehydes were positively correlated to the 'apricot' aroma, which were generally higher in the Viognier wines. Reconstitution studies confirmed that the monoterpenes linalool, geraniol, and nerol were the most important compounds for the mixture being perceived as having an 'apricot' aroma.