GC-MS Metabolite Profiling of Extreme Southern Pinot noir Wines: Effects of Vintage, Barrel Maturation, and Fermentation Dominate over Vineyard Site and Clone Selection

Abstract

Wine is an extremely complex beverage that contains a multitude of volatile and nonvolatile compounds. This study investiged the effect of vineyard site and grapevine clone on the volatile profiles of commercially produced Pinot noir wines from central Otago, New Zealand. Volatile metabolites in Pinot noir wines produced from five grapevine clones grown on six vineyard sites in close proximity, over two consecutive vintages, were surveyed using gas chromatography-mass spectrometry (GC-MS). The raw GC-MS data were processed using parallel factor analysis (PARAFAC2), and final metabolite data were analyzed by principal component analysis (PCA). Winemaking conditions, vintage, and barrel maturation were found to be the most dominant factors. The effects of vineyard site and clone were mostly vintage dependent. Although four compounds including β-citronellol, homovanillyl alcohol, N-(3-methylbutyl)acetamide, and N-(2-phenylethyl)acetamide discriminated the vineyard sites independent of vintage, Pinot noir wines from different clones were only partially discriminated by PCA, and marker compound selection remained challenging.

PTR‐MS volatile profiling of Pinot Noir wines for the investigation of differences based on vineyard site

“…The wines from high typicity sites are usually described as being higher in complexity, aroma and flavour, compared to wines from low typicity sites. The vineyard sites sampled have previously been described in detail . In short, the vineyard sites were located within an area of 13 km 2 (Central Otago, NZ).…”

“…A similar pattern was observed from the analysis of PB samples by SPE‐GC–MS, as previously reported . It was suggested that wines from the site BR had the potential to express high site‐typicity in their wines (as confirmed by subsequent discussions with the winemaker).…”

“…(B), loadings plot, circled m/z ). A similar pattern of discrimination in the PCA plots of the GC–MS data was previously reported …”

“…A pattern of sample discrimination based on site‐typicity, separating samples F6 and IN6_40% (green squares) from the high typicity samples (red triangles) was observed. The pattern previously reported was similar including sample BR5 being the most discriminated sample. The m/z describing BR5 were due to water clusters (39, 57), ethyl butyrate fragment (39), higher alcohol and ester fragments (41, 57, 58, 71), propanal/acetone (59), terpene fragments (41, 67), higher alcohols and their fragments (43, 61, 83), esters/acetic acid and their fragments (43, 61), aldehyde/carbonyl fragments (83), hexanoate ester and acid and fragments thereof (99, 117), furfuryl alcohol (99), hexanal/hexenols/2‐hexanone (101), ethyl butanoate/2‐heptanol (117) and ethylhexanoate/butyl butanoate/ethyl octanoate fragment (145) (Fig.…”

“…Gas chromatography mass spectrometry (GC–MS) analysis has previously been reported to be able to differentiate the VOC profiles of Mt. Difficulty Pinot Noir wines on the basis of their origin (vineyard site and clone) . While GC–MS enables the identification of VOCs, it is a time‐intensive approach as extraction and sample preparation are required.…”