 IVES 9 IVES Conference Series 9 Influence of must fining on wine pinking: relationship between electrochemical and colorimetric measurements and pinking attitude of wine

Influence of must fining on wine pinking: relationship between electrochemical and colorimetric measurements and pinking attitude of wine

Abstract

AIM: “Pinking” is a term used to define an abnormal pink coloration assumed by white wines in certain cases. Despite the are many hypotheses about the causes of this phenomenon, pinking still represents an issue for the wine industry. In the absence of reliable preventive strategies, wineries often rely on treatments such as charcoal fining, which is also negatively impacting wine aroma. This study aims at evaluating the potential of different fining agents based on animal or vegetal proteins to prevent wine pinking when applied at the level of must clarification. The work was carried out on Lugana wines, which is well-recognised as sensible to pinking problems.

METHODS: Two experimental Lugana musts were obtained by applying a standard winemaking protocol and were then clarified with different commercial preparations based on vegetal proteins or casein, alone or in combination with PVPP. A control only using pectolytic enzyme was also prepared. Finings were carried out at 4°C for 16h, and the clear must (200 NTU) was then fermented in controlled conditions. At the end of fermentation all wines were bottled with 25 mg/L of free SO2. Musts and wines were submitted to linear sweep voltammetry, colorimetric (CIELab) and spectrophotometric analyses. Pinking was assessed by CIELab.

RESULTS: Must fining with products based on combination of vegetable proteins and PVPP allowed significant reduction of must content in oxidizable compounds assessed by voltammetry, and this difference was still detected in the finished wines. After one month of bottle aging (free SO2 being 20 mg/L in all wines) pinking was detected for all wines except for those obtained from musts treated with potato or pea protein combined with PVPP. Voltammetric features of the must were shown to be well correlated with the risk of wine pinking. Analysis after one year of bottle aging confirmed the potential of fining to prevent pinking.

CONCLUSIONS: The type of fining agent used in must fining affects the occurrence of pinking in the finished wines. Vegetable proteins in combination with PVPP showed high potential for pinking prevention. Voltammetric analyses could be a promising tool for rapid assessment of the efficacy of fining treatments towards pinking.

ACKNOWLEDGMENTS:

The present work was financially supported by Biolaffort.

DOI:

Publication date: September 28, 2021

Issue: Macrowine 2021

Type: Article

Authors

Maurizio Ugliano 1, Riccardo MANARA 1, Eduardo VELA ROMAN 1, Virginie MOINE 1, Arnaud MASSOT 2, Davide SLAGHENAUFI 2.

1 University of Verona, Italy.
2 Biolaffort, France.

Contact the author

Keywords

pinking, fining, vegetable proteins, linear sweep voltammetry

Citation

Design of an indicator of vine vigor potential conferred by soil (vipos), using a fuzzy expert system

Winegrowers must adapt more and more their viticultural practices in order to evolve toward a sustainable viticulture, to be competitive and to improve both the production methods and the quality and typicalness of wines. In this context, ‘Terroir’ studies in Loire Valley vineyards have allowed to build decision aid maps that can be used directly by growers to adjust their practices.

Can grapevine intra-varietal genetic variability be a tool for climate change adaptation? A case study at a hot and dry environment

Climate change projections point to an increase of temperatures and changes in rainfall patterns in the mediterranean region.

A comprehensive ecological study of grapevine sensitivity to temperature; how terroir will shift under climate change

Fossil fuel combustion continues to drive increases in atmospheric carbon dioxide, consequently elevating the global annual mean temperature and specifically increasing the growing season temperatures in many of the world’s most important wine growing regions (IPCC 2014; Jones et al 2005). Grapes are sensitive to changes in growing season temperatures, and past models have shown a direct link between warming temperatures and earlier harvest dates (Cook and Wolkovich 2016). Globally, there have been shifts of 1-2 weeks for wine growing regions (Wolkovich et al 2017 and references within). The phenological shifts resulting from growing season temperature increases are documented internationally, and models predicting phenology using temperature are becoming more precise (Parker et al 2011).

Climate projections over France wine-growing region and its potential impact on phenology

Climate change represents a major challenge for the French wine industry. Climatic conditions in French vineyards have already changed and will continue to evolve. One of the notable effects on grapevine is the advancing growing season. The aim of this study is to characterise the evolution of agroclimatic indicators (Huglin index, number of hot days, mean temperature, cumulative rainfall and number of rainy days during the growing season) at French wine-growing regions scale between 1980 and 2019 using gridded data (8 km resolution, SAFRAN) and for the middle of the 21th century (2046-2065) with 21 GCMs statistically debiased and downscaled at 8 km. A set of three phenological models were used to simulate the budburst (BRIN, Smoothed-Utah), flowering, veraison and theoretical maturity (GFV and GSR) stages for two grape varieties (Chardonnay and Cabernet-Sauvignon) over the whole period studied. All the French wine-growing regions show an increase in both temperatures during the growing season and Huglin index. This increase is accompanied by an advance in the simulated flowering (+3 to +9 days), veraison (+6 to +13 days) and theoretical maturity (+6 to +16 days) stages, which are more noticeable in the north-eastern part of France. The climate projections unanimously show, for all the GCMs considered, a clear increase in the Huglin index (+662 to 771 °C.days compared to the 1980-1999 period) and in the number of hot days (+5.6 to 22.6 days) in all the wine regions studied. Regarding rainfall, the expected evolution remains very uncertain due to the heterogeneity of the climates simulated by the 21 models. Only 4 regions out of 21 have a significant decrease in the number of rainy days during the growing season. The two budburst models show a strong divergence in the evolution of this stage with an average difference of 18 days between the two models on all grapevine regions. The theoretical maturity is the most impacted stage with a potential advance between 40 and 23 days according to wine-growing regions.

Testing the pathogen e-learning and field training course on grapevine virus knowledge and management

One of the reasons of the spread of grapevine virus diseases in
vineyards around the world is the lack of knowledge by the main actors of the wine sector. To face this problem, five partners worked together to develop the PAThOGEN project, a training program aimed to improve grapevine virus knowledge and management. The partnership gathers one French technical center (IFV), one Spanish university (USC), one Italian applied research center (CREA), one Spanish foundation
specialized in training and technology transfer (FEUGA) and one Italian SME specialized in the development of informatics tools and in knowledge transfer (HORTA).The objectives of PAThOGEN are: (i) to develop and
maintain a high-quality work-based Vocational and Education Training program, (ii) to improve the skills of professionals of the wine sector.