 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

Can minimal pruning be a strategy to adapt grape ripening to global warming?

Berry maturation in warm areas takes place very early, when temperatures are still high and favorable for carbohydrate synthesis and accumulation in the berries, but not as favorable for maintaining high titratable acidity or low pH, or for increasing berry polyphenol content. Different canopy management techniques have been proven to delay berry maturation at the expense of yield (severe canopy trimming, late spring pruning to induce sprouting of dormant buds, etc.). Minimal pruning delays berry ripening by highly increasing yield and by reducing the leaf area to fruit ratio.

Relationship between terroir and acidity for the red wine grape cultivar Malbec N or Cot N (Vitis vinifera L.) in AOC “Cahors” and “Côtes du Frontonnais “

L’étude préliminaire, réalisée sur les principaux cépages de la région Midi-Pyrénées, a montré que le Cot N possédait des teneurs en acide tartrique dans les moûts et les vins plus élevées que celles des cépages Négrette N, Tannat N, Duras N et Fer Servadou N.

Zonage viticole des surfaces potentielles dans la vallée Centrale de Tarija (Bolivie)

La présente étude de zonage viticole a été faite dans la région de la vallée Central de Tarija(VCT), dans la ville de Tarija, au Sud de la Bolivie; une région avec plus de 400 années de tradition qui présente une vitiviniculture de haute qualité. La Vallée possède une surface total de 332 milles ha.; existant des vignobles entre 1660 y 2300 m.s.n.m. et dans ce rang d’altitude il existe 91 mille ha.

Removal of Fumonisin B1 and B2 from red wine using polymeric substances

The Ability of PVPP (Polyvinylpolypyrrolidone), PVP-DEGMA-TAIC (copolimerization of N-vinyl-2-pyrrolidinone with ethylene glycol dimethacrylate and triallyl isocyanurate) and PAEGDMA
(poly(acrylamide-co-ethylene glycol dimethacrylate)) polymers was tested as removal agents for Fumonisin B1 (FB1) and Fumonisin B2 (FB2) from model solutions and red wine. The polymers removal capacity was checked at three different resident times (2, 8 and 24 hours of contact time between the polymer and the sample), showing no differences in the percentage of FB1 and FB2 removal. Then, different polymer concentrations (1, 5 and 10 mg mL-1) were tested in model solution with and without phenolics (i.e. gallic acid and 4-methylcatechol).

Linear sweep voltammetry to classify and characterize the antioxidant properties of tannins

In recent years, numerous studies have been carried out at the OIV on oenological tannins, both with regard to oenological properties and methods of characterization. The results of these recent studies have led to the revision of the general monograph and the drafting of four new monographs, one for each of the four chemical classes into which the tannins have been grouped: ellagitannins, gallotannins, procyanidins/prodelphinidins, profisetinidins/prorobinetinins.