 IVES 9 IVES Conference Series 9 Macrowine 9 Macrowine 2021 9 Chemical diversity of 'special' wine styles: fortified wines, passito style, botrytized and ice wines, orange wines, sparkling wines 9 The effects of antioxidants and gas sparging on New Zealand white wines

The effects of antioxidants and gas sparging on New Zealand white wines

Abstract

AIM: This study aims to investigate the effects of different conditions of grape processing or fermentation on the aroma profile of New Zealand white wines.

METHODS: Experiments have been designed to study how glutathione and ascorbic acid impact on the aroma compounds of Sauvignon Blanc and Pinot Gris wines. Attention was also paid to the effectiveness of two gas sparging regimes (oxygen and nitrogen), applied during fermentation, on the removal of reductive sulfur aromas in Sauvignon Blanc wines.

RESULTS: Additions of glutathione to the grape juices increased the levels of polyfunctional mercaptans in the finished wines. The lowest levels of polyfunctional mercaptan compounds were found in the wines with little supplementary antioxidants added. A high level of the joint combination of ascorbic acid and glutathione provided the wines with even higher production of polyfunctional mercaptans. Increasing the amount of elemental sulfur addition to the grape must before pressing led to an increase in the formation of several thiol compounds, including some unwanted reductive compounds. Few changes were observed in the concentrations of aroma compounds when the juices were sparged with nitrogen during fermentation. Additions of oxygen during fermentation led to some decrease in the concentration of polyfunctional mercaptans for the 10 mg/L sulfur additions, but did not significantly remove reductive aroma compounds.

CONCLUSIONS

This study has demonstrated a positive benefit to the formation of polyfunctional mercaptans with passionfruit/ tropical aromas, from additions of glutathione and ascorbic acid at harvest. The oxygen or nitrogen applied during fermentation did not result in the removal of undesirable reductive aroma compounds. Further trials are needed to examine increased oxygen as well as nitrogen dosages during fermentation, and their effects on reductive compounds.

DOI:

Publication date: September 15, 2021

Issue: Macrowine 2021

Type: Article

Authors

Xiaotong Lyu

School of Chemical Sciences, University of Auckland, Private Bag 92019, Auckland, New Zealand,Leandro Dias ARAUJO, School of Chemical Sciences, University of Auckland, Private Bag 92019, Auckland, New Zealand Siew-Young QUEK, School of Chemical Sciences, University of Auckland, Private Bag 92019, Auckland, New Zealand Wessel. J. DU TOIT, Institute for Grape and Wine Sciences/Department of Viticulture and Oenology, Stellenbosch University, Private Bag X1, Matieland 7602, South Africa Paul. A. KILMARTIN*, School of Chemical Sciences, University of Auckland, Private Bag 92019, Auckland, New Zealand

Contact the author

Keywords

sauvignon blanc, pinot gris, antioxidants, glutathione, ascorbic acid, reductive compounds, oxygen, nitrogen, polyfunctional mercaptans

Citation

Classification and prediction of tannin botanical origin through voltammetry and machine learning approach

The classification of enological tannins has gained importance following the OIV’s requirement to include their botanical origin on product labels (OIV-OENO624-2022).

Caractérisation des relations hydriques sol/vigne dans un terroir languedocien

Par le fait d’une politique agricole communautaire axée sur des objectifs de qualité des produits, la recherche et l’identification des critères de cette qualité deviennent impératives. En viticulture, la notion de qualité du produit est rattachée au concept théorique de «terroir». Ce terme englobe un ensemble de paramètres du milieu (géologie, sol, climat) influant sur la récolte.

The influence of RNAi-expressing rootstocks in controlling grey mold on grapevine cultivars

Worldwide, with an average of 6.7 million cultivated hectares, of which exclusively 51% in Europe (faostat, 2021), the production of table and wine grapes is a leading sector, with continued growth in Europe in the area devoted to vine cultivation. during the growing season, most of the plant organs can be susceptible to several fungal and oomycete diseases, leading to important economic losses and causing detrimental effects on fruit quality. the increasingly scarce availability of fungicidal products, often also related to their relative impact on the environment, coupled with the emergence of resistance in the pathogen to these products, make defence increasingly challenging.

Correlation between skin cell wall composition and phenolic extractability in Cabernet sauvignon wines

The phenolic component of red wine is responsible for important elements of flavor and mouthfeel, and thus quality of the finished wine. Additionally, many of these phenolics have been associated with health benefits such as reduction of the risk of developing cardiovascular disease, cancer, osteoporosis and preventing Alzheimer’s disease. While the origins, concentrations, and chemistries of the phenolics in a finished red wine are well known, the fundamental mechanisms and kinetics of extraction of these phenolics from grape skins and seeds during red wine fermentation are poorly understood. This lack of knowledge regarding the extraction mechanisms of phenolics during red wine fermentation makes informed manipulations of the finished wine’s phenolic composition difficult.

Rationalizing The Wine Nucleophilic Competition For Quinone Addition

loss and color browning which lead to wine unacceptance by consumers. These changes are mainly driven by the consumption of oxygen by polyphenols leading to the production of quinones which are oxidant compounds. Quinones can react with numerous nucleophilic compounds notably aromatic thiols, decreasing the aromatic bouquet of the wine.