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…

Organic recycled mulches in sustainable viticulture: assessment of spontaneous plants communities and weed coverage

In recent years, developing more efficient and sustainable viticulture management has been essential due to the impact of climate change in semiarid regions. For this reason, the use of recycled organic mulching (ROM) in the vineyard has become an interesting strategy to cope with water stress, isolated soil from extreme temperatures and improving soil humidity, control the presence of weeds and therefore reduce the inputs of herbicides and improve soil fertility. This work aimed to analyse the effect of three different organic mulches [straw (S), grape pruning debris (GPD) and spent mushroom compost (SMC)] and two traditional soil management techniques [herbicide (H) and interrow (IN)] on weed coverage and the spontaneous plant communities’ presence. Data sampling was collected throughout the vine vegetative cycle of 2021 in La Rioja, Spain. The different soil management techniques had a clear effect on weed coverage and his development during the vine vegetative cycle. SMC and H were the treatments with the highest and the lowest coverage percentage, respectively. IN had a delayed weed emergence at the beginning of the vine vegetative cycle, but finally it reached maximum values nearby SMC. GPD and S had similar effects on weed emergence, reaching 25-30% of the maximum coverage values. A total of 29 herbaceous species were identified during the vegetative cycle, some of them very isolated and occasional. Principal component analysis (PCAs) showed a good association between spontaneous species and treatments, furthermore, specific species-treatment associations were found. Moreover, three clear groups of herbaceous communities were identified by cluster analysis. This study provides interesting information about the effect of different alternative soil management on herbaceous plant coverage and weed species communities which could contribute to making more sustainable viticulture.

Phenological characterization of a wide range of Vitis Vinifera varieties

In order to study the impact of climate change on Bordeaux grape varieties and to assess the adaptation capacities of candidates to the grape varieties of this wine region to the new climatic conditions, an experimental block design composed of 52 grape varieties was set up in 2009 at the INRAE Bordeaux Aquitaine center. Among the many parameters studied, the three main phenological stages of the vine (budburst, flowering and veraison) have been closely monitored since 2012. Observations for each year, stage and variety were carried out on four independent replicates. Precocity indices have been calculated from the data obtained over the 2012-2021 period (Barbeau et al. 1998). This work allowed to group the phenological behaviour of the grapevine varieties, not only based on the timing of the subsequent developmental stages, but also on the overall precocity of the cycle and the total length of the cycle between budburst and veraison. Results regarding the variability observed among the different grape varieties for these phenological stages are presented as heat maps.

The modification of cultural practices in grapevine cv. Syrah, does it modify the characteristics of the musts?

The work shows the results of a year of experimentation (2020) in a Syrah variety vineyard in La Roda (Castilla-La Mancha, Spain). The trial approach was on a randomized block design with two factors: Irrigation (I) and Pruning (P).
Irrigation schedules were adjusted to apply amounts close to 1,500 m3/ha. With this provision, 2 different irrigation treatments were proposed: I1) Start of irrigation from pea-sized grape to post-harvest (providing at least 20 % of the total amount of irrigation water to be provided post-harvest); I2) Start of irrigation from pea-sized grape to harvest (usual irrigation practice in the study area). Pruning was proposed with two treatments, one at the end of January (P1), which is pruning on a conventional date; and P2) pruning carried out at the beginning of budding. In total, 4 repetitions were designed with 4 elementary plots, each one of them representing one of the proposed treatments (I1P1; I1P2; I2P1; I2P2). In total, 16 plots were worked on and each elementary plot consisted of 30 strains, distributed in 3 lines.
The productive response was evaluated with the yield results of the harvest harvested at 23 ºBrix. The qualitative response was measured in the musts through the indices of technological (acidity, pH and potassium) and phenolic maturity and aromatic compounds in free and glycosylated fractions. The treatments tested had, in general, an effect on the different variables analyzed.

Influence of weather and climatic conditions on the viticultural production in Croatia

The research includes an analysis of the impact of weather conditions on phenological development of the vine and grape quality, through monitoring of four experimental cultivars (Chardonnay, Graševina, Merlot and Plavac mali) over two production years. In each experimental vineyard, which were evenly distributed throughout the regions of Slavonia and The Croatian Danube, Croatian Uplands,

Mesoclimate impact on Tannat in the Atlantic terroir of Uruguay

The study of climate is relevant as an element conditioning the typicity of a product, its quality and sustainability over the years. The grapevine development and growth and the final grape and wine composition are closely related to temperature, while climate components vary at mesoscale according to topography and/or proximity to large bodies of water. The objective of this work is to assess the mesoclimate of the Atlantic region of Uruguay and to determine the effect of topography and the ocean on temperature and consequently on Tannat grapevine behavior.