IVAS 2022 banner
IVES 9 IVES Conference Series 9 IVAS 9 IVAS 2022 9 New insight the pinking phenomena of white wine

New insight the pinking phenomena of white wine

Abstract

Pinking of white wine is an undesired change potentially occurring over storage, leading to the turning of color from yellow into salmon-red hue. Recently, the appearance of pink color was associated to small concentrations of malvidin-3-O-glucoside (∼ 0.3mg/L) present in white wines produced under reducing conditions from Síria grape variety [1]. Other suggested mechanisms were the polymerization of anthocyanins under oxidative condition, the combination of more than ten different monomers and polymeric compounds, the formation of a derivative from 2-S-glutathionyl-caftaric acid [2]. However, this color modification has been not fully understood. This study aimed to clarify the molecular mechanisms and the compound(s) involved in the pinking of white wine. 
The appearance of pinking was evaluated in model wine added with increasing concentrations of sulfur-containing compounds (i.e. glutathione, cysteine, mercaptoethanol), and fixed amounts of the phenolics (i.e. catechin and caffeic acid), singularly or in combination. An assay with copper, with and without phenolics, was also carried out. The oxidation was generated by adding p-benzoquinone in both oxic and anoxic conditions. The intensity of pink color was measured at 520 nm. A major compound associated to pinking was detected by UPLC-UV and its molecular weight and structure were investigated by High Resolution Mass Spectrometry (HRMS) and Nuclear Magnetic Resonance (NMR), respectively.
In most of the tested conditions, the pink color appeared and resulted more intense with catechin. On the contrary, the color was yellow-brownish in the absence of phenolics notwithstanding the presence of copper. Considering the single addition of the thiol compounds, the major pink intensity and the fastest appearance were due to cysteine. The pinking intensity was lower with glutathione and it was not detected with mercaptoethanol. Catechin was the phenolic mainly involved into the pinking. The rate of pinking formation was dependent on both the thiol/p-benzoquinone and catechin/p-benzoquinone molar ratios with the former playing a paramount role. Copper was also involved in this phenomenon The major formation rate was observed when thiol/p-benzoquinone molar ratio was about 0.7. The compound associated to the pink color showed a maximum adsorption at 505 nm, characteristic of anthocyanin-like moieties and its accurate mass ([M+H]+) was 450.0635 Da. NMR analysis evidenced three molecular forms in equilibrium. The estimated conversion yield was 5%.These data suggest that pinking phenomena, in our experimental conditions, is due to the oxidation of catechin with the aid of sulphur-containing compounds, the latter with a crucial role for this color change.

References

[1] Andrea-Silva J., Cosme F., Ribeiro L. F., Moreira A. S. P., Malheiro A. C., Coimbra M. A., Domingues M. R. M., & Nunes F. M. (2014). Origin of the pinking phenomenon of white wines. Journal of Agriculture and Food Chemistry, 62(24), 5651–5659. https://doi.org/10.1021/jf500825h.
[2] Gabrielli M., Fracassetti D., Romanini E., Colangelo D., Tirelli A., Lambri, M. (2021). Oxygen-induced faults in bottled white wine: A review of technological and chemical characteristics. Food Chemistry, 348, 128922. https://doi.org/10.1016/j.foodchem.2020.128922.

DOI:

Publication date: June 23, 2022

Issue: IVAS 2022

Type: Article

Authors

Ragg Enzio1, De Noni Ivano1 and Tirelli Antonio1

1Department of Food, Environmental and Nutritional Sciences (DeFENS), Università degli Studi di Milano, Via G. Celoria 2, 20133 Milan, Italy

Contact the author

Keywords

Pinking, Oxidation, Quinones, Cysteine, Catechin

Tags

IVAS 2022 | IVES Conference Series

Citation

Related articles…

Preplant fumigation only temporarily reduces Northern root-knot nematode

Management of plant-parasitic nematodes is typically focused on preplant fumigation, especially in a vineyard replant scenario. While the data are clear that this practice reduces nematodes immediately after application, which is useful in annually-cropped systems, does it have staying power in perennial cropping systems? The northern root-knot nematode Meloidogyne hapla reduces the overall lifespan and productivity of vineyards, but it does so over a long time period (slow, chronic decline). In two different commercial own-rooted V. vinifera vineyards, both undergoing vineyard replanting, we explored whether preplant fumigation reduced M. hapla densities in soils immediately after application. At one of these locations, we have explored the long-term effect of fumigation by monitoring the site for seven years post fumigation.

Trends and challenges in International Wine Trade. The need for new strategies for companies and regions.

Trends already extended for more than 12 years show a decline in both consumption and international trade, particularly in volume. However, there are also positive signs in several categories of wine, segments and markets, as well as a better trend in terms of value. How are these trends affecting wine producers and distributors? Are they short or long term? do they mean radical and permanent changes to which a way of adaptation has to be found or are they just temporary changes that may only require some calm? How are companies adapting to these new trends? Which are their effects on wine regions?

Generation of radicals in wine by cavitation and study of their interaction with metals, phenols and carboxylic acids

High-power ultrasounds have been related to an accelerated aging of wines, an effect that has been associated to the formation of radical species caused by the cavitation phenomenon [1]. This phenomenon consists of the formation of bubbles in the liquid medium that, when they collapse, cause high-pressure hot spots and temperatures of up to 4800 k [2], notably increasing the reactivity in the medium.

Evaluation of clonal variability of phenolic compounds in Vitis vinifera L. cv. Trnjak crni grown in Croatia

Context and purpose of the study. Croatia has rich grapevine genetic resources with more than 130 native varieties preserved.

Projected changes in vine phenology of two varieties with different thermal requirements cultivated in La Mancha DO (Spain) under climate change scenarios

The aim of this work was to analyze the phenology variability of Tempranillo and Chardonnay cultivars, related to the climatic characteristics in La Mancha Designation of Origin, and their potential changes under climate change scenarios. Phenological dates referred to budbreak, flowering, veraison and harvest were analyzed for the period 2000-2019. The weather conditions at daily time scale, recorded during the same period, were also evaluated. The thermal requirements to reach each of these phenological stages were calculated and expressed as the GDD accumulated from DOY=60. Changes in phenology were projected by 2050 and 2070 taking into account those values and the projected temperatures and precipitation, simulated under two Representative Concentration Pathway (RCP) scenarios –RCP4.5 and RCP8.5– using an ensemble of models. The average phenological dates during the period under study were, April 16th ± 6.6 days and April 5th ± 6.0 days for budbreak, May 31st ± 6.0 days and May 27th ± 5.3 days for flowering, July 26th ± 5.6 days and July 25th ± 5.8 days for veraison, and Ago 23rd ± 10.8 days and Ago 17th ± 9.0 days for harvest, respectively, for Tempranillo and Chardonnay. The projected changes in temperature imply an average change in the maximum growing season (April-August) temperatures of 1.2 and 1.9°C by 2050, and 1.6 and 2.6°C by 2070, under the RCP4.5 and RCP8.5 scenarios, respectively. A reduction in precipitation is predicted, which vary between 15% for 2050 under RCP4.5 scenario and up to 30% by 2070 under RCP8.5. The advance of the phenological dates for 2050, could be of 6, 7, 7, and 8 days for Tempranillo and 4, 6, 6 and 9 days for Chardonnay, respectively for budbreak, flowering, veraison and harvest under the RCP4.5 scenario. Under the RCP8.5 emission scenario, the advance could be up to 30% higher.