Methoxypyrazine concentrations in the grape bunch rachis of Vitis vinifera L. Cv Shiraz: Influence of rootstock, region and light

Ross D Sanders; Paul K Boss; Dimitra L Capone; Catherine M Kidman; Sue Maffei; David W Jeffery

doi:10.1016/j.foodchem.2022.135234

Methoxypyrazine concentrations in the grape bunch rachis of Vitis vinifera L. Cv Shiraz: Influence of rootstock, region and light

Food Chem. 2023 May 15:408:135234. doi: 10.1016/j.foodchem.2022.135234. Epub 2022 Dec 17.

Authors

Ross D Sanders¹, Paul K Boss², Dimitra L Capone³, Catherine M Kidman⁴, Sue Maffei⁵, David W Jeffery⁶

Affiliations

¹ Department of Wine Science and Waite Research Institute, The University of Adelaide, Waite Campus, PMB 1, Glen Osmond, South Australia 5064, Australia; CSIRO Agriculture and Food, Waite Campus, Locked Bag No. 2, Glen Osmond, South Australia 5064, Australia; Australian Research Council Training Centre for Innovative Wine Production, The University of Adelaide, Waite Campus, PMB 1, Glen Osmond, South Australia 5064, Australia.
² CSIRO Agriculture and Food, Waite Campus, Locked Bag No. 2, Glen Osmond, South Australia 5064, Australia; Australian Research Council Training Centre for Innovative Wine Production, The University of Adelaide, Waite Campus, PMB 1, Glen Osmond, South Australia 5064, Australia.
³ Department of Wine Science and Waite Research Institute, The University of Adelaide, Waite Campus, PMB 1, Glen Osmond, South Australia 5064, Australia; Australian Research Council Training Centre for Innovative Wine Production, The University of Adelaide, Waite Campus, PMB 1, Glen Osmond, South Australia 5064, Australia.
⁴ Wynns Coonawarra Estate, Memorial Drive, Coonawarra, South Australia 5263, Australia.
⁵ CSIRO Agriculture and Food, Waite Campus, Locked Bag No. 2, Glen Osmond, South Australia 5064, Australia.
⁶ Department of Wine Science and Waite Research Institute, The University of Adelaide, Waite Campus, PMB 1, Glen Osmond, South Australia 5064, Australia; Australian Research Council Training Centre for Innovative Wine Production, The University of Adelaide, Waite Campus, PMB 1, Glen Osmond, South Australia 5064, Australia. Electronic address: david.jeffery@adelaide.edu.au.

PMID: 36599227
DOI: 10.1016/j.foodchem.2022.135234

Abstract

Vitis vinifera L. cv Shiraz appears unable to synthesise 3-alkyl-2-methoxypyrazines (MPs) in the berry, but can still produce significant concentrations in rachis. MPs are readily extracted from rachis during fermentation, producing Shiraz wines with uncharacteristic "green" flavours. Recently, rootstocks were shown to significantly alter MP concentrations in Cabernet Sauvignon rachis compared to own-rooted varieties, but whether Shiraz followed a similar trend required investigation. This study considered the effect of thirteen rootstocks on the concentrations of 3-isobutyl-2-methoxypyrazine (IBMP), 3-isopropyl-2-methoxypyrazine (IPMP), and 3-sec-butyl-2-methoxypyrazine (SBMP) in the rachis of Shiraz bunches sampled during multiple vintages across several Australian growing regions. Although IBMP was the most abundant, all measured MP concentrations were significantly affected by vintage, rootstock, and region. In addition, vine vigour showed positive correlations with IBMP, which were attributed to changes in canopy coverage impacting rachis light exposure. This hypothesis was explored with light exclusion trials, which significantly increased rachis IBMP concentrations.

Keywords: 3-isobutyl-2-methoxypyrazine; GC–MS; Green aroma; Light exposure; Stable isotope dilution assay; Terroir; Wine aroma.

MeSH terms

Australia
Fruit
Vitis*
Wine* / analysis