OENO IVAS 2019 banner
IVES 9 IVES Conference Series 9 Simplifying the measurement of different forms of cu in wines and strategies for efficient removal

Simplifying the measurement of different forms of cu in wines and strategies for efficient removal

Abstract

Copper (Cu) is known to substantially impact wine stability through oxidative, reductive or colloidal phenomena. Recent work has shown that Cu exists predominantly in a sulfide-bound form, which may act as a potential source of sulfidic off-odours in wine and hence contribute to reductive flavours. The quanti-fication of different forms of copper in wine may allow winemakers to target more effective strategies for the removal of Cu and also to better understand the likelihood of reductive characters emerging in wines during aging.

A simple colorimetric method, utilising bicinchonic acid (BCA), was validated for the determination of the different forms of Cu in white wines, as well as the total Cu concentration in red wine. The determination of total Cu in white wines utilises an addition of excess silver(I) in order to effectively release copper from sulfide and allow quantitative complexation by BCA. The non-sulfide bound form of Cu in the white wine was determined by BCA analysis of the white wine without silver addition. In the case of red wines, a simple digestion procedure eliminated colour prior to subsequent analysis as per the white wines. The total Cu measured by the colorimetric method had an accuracy equivalent to ICPOES and a linear range of 0.04 to 1.0 mg/L. The different forms of Cu measured in white wines agreed with the results obtained by a more laborious electrochemical method.

The removal of different forms of Cu from white and red wine was subsequently studied using membrane filters of various media and pore size, depth filters and PVI/PVP. Only PVI/PVP could efficiently remove both forms of Cu, whilst the filtration techniques displayed activity for removing the sulfide bound form of Cu. Of the membrane filters, nylon and polytetrafluoroethylene media could adsorb sulfide-bound Cu, with little dependence on pore size, but their capacity for removal decreased rapidly with wine filtration volume. Similar results were observed with cellulose-based depth filters, but much greater removal efficiency was observed for cellulose depth filters impregnated with diatomaceous earth. This type of filter had active re-moval of sulfide-bound Cu from larger volumes of wine. The results allow rapid determination of the Cu forms in wine along with the assessment of the best strategies for their removal.

Abbreviations: PVI/PVP, polyvinylimidazole/polyvinylpyrrolidone.

DOI:

Publication date: June 10, 2020

Issue: OENO IVAS 2019

Type: Article

Authors

Nikolaos Kontoudakis Kieran Hirlam, Mark Smith, Paul Smith, Neil Scrimgeour, Paul Bowyer, Eric Wilkes, Andrew Clark

Andrew Clark: Charles Sturt University-National Wine and Grape Industry Centre Eric Wilkes, Neil Scrimgeour, Kieran Hirlam, Mark Smith: The Australian Wine Research Institute Mark Smith: Wine Australia Paul Bowyer: Blue H2O Filtration

Contact the author

Keywords

Copper measurment , Sulfide-bound Cu, Filtration , PVP/PVI 

Tags

IVES Conference Series | OENO IVAS 2019

Citation

Related articles…

Physiological and growth reaction of Shiraz/101-14 Mgt to row orientation and soil water status

Advanced knowledge on grapevine row orientation is required to improve establishment, management and outcomes of vineyards on terroirs with different environmental conditions (climate, soil, topography) and in view of a future change to more extreme climatic conditions. The purpose of this study was to determine the combined effect of row orientation, plant water status and ripeness level on the physiological and viticultural reaction of Shiraz/101-14 Mgt.

Read More

Effects of mechanical leafing and deficit irrigation on Cabernet Sauvignon grown in warm climate of California

San Joaquin Valley accounts for 40% of wine grape acreage and produces 70% of wine grape in California. Fruit quality is one of most important factors which impact the economical sustainability of farming wine grapes in this region. Due to the recent drought and expected labor cost increase, the wine industry is thrilled to understand how to improve fruit quality while maintaining the yield with less water and labor input. The present study aims to study the interactive effects of mechanical leafing and deficit irrigation on yield and berry compositions of Cabernet Sauvignon grown in warm climate of California.

Read More

The effects of cane girdling on berry texture properties and the concentration of some aroma compounds in three table grape cultivars

The marketability of the table grapes is highly influenced by the consumer demand; therefore the market value of the table grapes is mainly characterized by its berry size, colour, taste and texture. Girdling could cause accumulation of several components in plants above the ringing of the phloem including clusters and resulting improved maturity. The aim of the experiments was to examine the effect of girdling on berry texture characteristics and aroma concentration.

Read More

Application of a fluorescence-based method to evaluate the ripening process and quality of Pinot Blanc grape

The chemical composition of grape berries at harvest is one of the most important factors that should be considered to produce high quality wines. Among the different chemical classes which characterize the grape juice, the polyphenolic compound, such as flavonoids, contribute to the final taste and color of wines. Recently, an innovative non-destructive method, based on chlorophyll fluorescence, was developed to estimate the phenolic maturity of red grape varieties through the evaluation of anthocyanins accumulated in the berry skin. To date, only few data are available about the application of this method on white grape varieties.

Read More

Different yield regulation strategies in semi-minimal-pruned hedge (SMPH) and impact on bunch architecture

Yields in the novel viticulture training system Semi-Minimal-Pruned Hedge (SMPH) are generally higher compared to the traditional Vertical Shoot Positioning (VSP). Excessive yields have a negative impact on the vine and wine quality, which can result in substantial losses in yield in subsequent vintages (alternate bearing) or penalties in fruit quality. Therefore yield regulation is essential. The bunch architecture in SMPH differs from VSP. Generally there is a higher amount but smaller bunches with lower single berry weights in SMPH compared to VSP.

Read More