 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

Altered lignans accumulation in a somatic variant of Tempranillo with increased extractability of polyphenols during winemaking

Vegetative propagation of grapevines can generate spontaneous somatic variations, providing a valuable source for cultivar improvement. In this context, natural variation in the composition of phenolic compounds in grapevine berries and seeds stands as a pivotal factor in crafting wines with diverse oenological profiles from the same cultivar. To deepen on the understanding of the physiological and genetic mechanisms driving somatic variation in grape phenolics, here we characterized a somatic variant from Tempranillo Tinto, the clone VN21, that exhibits an intense reduced berry skin cuticle and increased extractability of phenolic compounds during wine fermentation.

Influence Of Different Grape Polysaccharides On Phenolic Compounds And Colour Characteristics Of Tempranillo Red Wines

Polysaccharides (PS) are one of the main compounds found in wines, and they come mainly from the grape cell walls or from the yeasts, and they play an important role in the technological and sensory characteristics of wines. Polysaccharides obtained from yeasts have been more studied, especially mannoproteins, since there are commercial products.

White wine lees: unlocking the relationship between chemical composition and antioxidant potential

The wine-making process generates numerous by-products at each stage (crushing, fermentation, ageing), including wine lees, which account for almost 25% of the total quantity.

Modélisation du régime thermique des sols de vignoble du Val de Loire : relations avec des variables utilisables pour la caractérisation des terroirs

Temperature has a decisive influence on the growth and development of plants (Carbonneau et al., 1992). In particular, in the case of the vine, the temperature is an omnipresent variable in the climatic indices (Huglin, 1986). For reasons of convenience, these indices use the temperature of the air measured under shelter in a meteorological station, making the implicit hypothesis of a concordance between this temperature and that of the sites of perception of the thermal stimulus by the plant. However, development may be more dependent on soil temperature than air temperature (Kliewer, 1975). Morlat (1989) thus verified that the variability in the precocity of the vine, positively correlated with the quality of the harvest and of the wine in the Loire Valley, was mainly explained by differences in temperature of the root zones.

Armenia: historical origin of domesticated grapevine

The Armenian highlands are located on the northern border of western asia and stretch up to the caucasus from the north. Throughout human history, country has played an important role in connecting the civilizations of europe and the near east. The recent large-scale study about the dual domestication origin and evolution of grapes approved that in the Armenian highlands human and grapevine stories are interlaced through centuries and roots of grapevine domestication are found deep in the pleistocene, ending 11.5 thousand years ago. Findings of this study confirmed that glacial episodes distinguish wild grapes into eastern and western ecotypes around 200-400 ka.