Clonal differences and impact of defoliation on Sauvignon blanc (Vitis vinifera L.) wines: a chemical and sensory investigation.
BACKGROUND
The aim of this study, performed on Sauvignon blanc clones SB11 and SB316, grafted on the same rootstock 101-14 Mgt (Vitis riparia × V. ruperstris) and grown at two adjacent vineyards, was two-fold: (1) to study wine chemical and sensory composition of both clones within an unaltered canopy; and (2) to determine the effect of defoliation (e.g. bunch microclimate) on wine chemical and sensory composition.


RESULTS
Orthogonal projection to latent structures discriminate analysis (OPLS-DA) was applied to the concentration profiles of volatile compounds derived from gas chromatography-mass spectrometry data. The loadings directions inferred that 3-isobutyl-2-methoxypyrazine (IBMP) discriminated control treatments (shaded fruit zone) of both clones from defoliation treatments (exposed fruit zone), whereas 3-sulfanyl-hexan-1-ol (3SH), 3-sulfanylhexyl acetate (3SHA), hexanol, hexyl hexanoate and some other esters discriminated defoliated treatments from the controls. The OPLS-DA indicated the importance of IBMP, higher alcohol acetates and phenylethyl esters, for discrimination of clone SB11 from clone SB316 irrespective of the treatment. Defoliation in the fruit zone significantly decreased perceived greenness in clone SB11 and elevated fruitier aromas, whereas in clone SB316 the effect of defoliation on wine sensory perception was less noticeable regardless the decrease in IBMP concentrations.


CONCLUSIONS
These findings highlight the importance of clone selection and bunch microclimate to diversify produced wine styles.
Institute for Wine Biotechnology, Department of Viticulture and Oenology, Stellenbosch University, P.O. Box X1, Matieland, Stellenbosch 7602, South Africa.
Katja
K
Šuklje
Institute for Wine Biotechnology, Department of Viticulture and Oenology, Stellenbosch University, P.O. Box X1, Matieland, Stellenbosch 7602, South Africa.
Guillaume
G
Antalick
Department of Viticulture and Oenology, Stellenbosch University, P.O. Box X1, Matieland, Stellenbosch 7602, South Africa.
Astrid
A
Buica
Department of Viticulture and Oenology, Stellenbosch University, P.O. Box X1, Matieland, Stellenbosch 7602, South Africa.
Jennifer
J
Langlois
Department of Viticulture and Oenology, Stellenbosch University, P.O. Box X1, Matieland, Stellenbosch 7602, South Africa.
Zelmari A
ZA
Coetzee
Institute for Wine Biotechnology, Department of Viticulture and Oenology, Stellenbosch University, P.O. Box X1, Matieland, Stellenbosch 7602, South Africa.
Julia
J
Gouot
National Wine and Grape Industry Centre, Charles Sturt University, Locked Bag 588, WaggaWagga, NSW 2678, Australia.|School of Agricultural and Wine Science, Charles Sturt University, Locked Bag 588, WaggaWagga, NSW 2678, Australia.
Leigh M
LM
Schmidtke
Department of Viticulture and Oenology, Stellenbosch University, P.O. Box X1, Matieland, Stellenbosch 7602, South Africa.
Alain
A
Deloire
D005511:Food Handling; D008401:Gas Chromatography-Mass Spectrometry; D006801:Humans; D008834:Microclimate; D013019:South Africa; D027843:Vitis / Q000235:genetics*; D055549:Volatile Organic Compounds / Q000737:chemistry*; D014920:Wine
D055549:Volatile Organic Compounds
esters; methoxypyrazines; sensory; thiols; viticulture