We often hear from our customers about the evolution of the colour of their red wine, which could be attributed to numerous things. Here are some elements of the answers regarding the prevention of any loss and the stability of the red pigments in wines.
Red wines owe their colour to pigments that are extracted from the skins during maceration in fermentation tanks. These are anthocyanins and are found in the grape skin of all red varieties and the pulp of dyer grape varieties.
During fermentation and maceration, anthocyanins are extracted from the skins of the grapes and end up in the must, contributing to the colour of the wine, both in terms of intensity and nuance.
Under the influence of various factors, such as the concentration of tannins, pH, temperature, and the presence of other compounds, tannins can react with each other and form chemical bonds, which leads to their polymerisation.
The chemical bonds formed during the polymerisation of tannins can be of different types, including ether bonds and ester bonds. The polymerisation of tannins leads to the formation of larger, insoluble tannin complexes, which contribute to a smoother mouthfeel and a more rounded tannic structure in wine.
Anthocyanins can also undergo polymerisation, forming complexes with the tannins present in the must. This polymerisation of anthocyanins with tannins enhances colour stability in wine, preventing pigments from degrading or discolouring over time.
Maceration enzymes are essential in enabling polyphenols to enter the juice. It weakens the pulp cell walls and accelerates and promotes the release of pulp juice and the interaction of this juice with skin cells. This means that extractions can start early. That is why the initial addition of maceration enzymes has a big impact on the order of the extractions and, by extension, on the stabilisation.
A full page is dedicated to how to better extract pigment. Click here.
It should be mentioned that the polymerisation of tannins and anthocyanins is a complex process and can be influenced by many factors, such as the grape variety, the stage of ripeness of the grapes, winemaking techniques, and ageing conditions. Winemakers can use different physical methods, such as prolonged maceration, ageing in oak barrels, and controlled micro-oxygenation, to encourage polymerisation and thus obtain red wines with a balanced tannic structure and a stable and intense colour.
Rapidase Extra Fruit has a decisive impact on the extraction of aroma precursors from grape skins and also on colour quality. It works in perfect synergy with dedicated yeast strains such as Fermivin P21, Fermivin VR5, Anchor Exotics Novello, Exotics Mosaic, and Legacy WE372 to take advantage of the cinnamoylesterase activity of this enzyme formulation. The synergic effect of Rapidase Extra Fruit combined with one of those yeasts promotes the formation of vinylpyranoanthocyanins, which limit the risk of ethylphenol off-flavour formation while stabilising colour.
Volatile phenols are produced in several stages from precursors already present in the grapes. One of the stages of their formation generates the production of intermediates called vinyl phenol and vinylguaiacol.
During the alcoholic fermentation of red wine, an addition of vinylphenols and guaiacol with anthocyanins is observed, resulting in the synthesis of complex, stable pigments, the vinylpyranoanthocyanins (VPA).
This reaction is possible only when specific Saccharomyces cerevisiae strains exhibiting hydroxycinnamate decarboxylase (HCDC) activity are used, which leads to the formation of vinylphenols that interact immediately with anthocyanins extracted during the alcoholic fermentation.
Fermivin P21, Fermivin VR5, and Fermivin A33 yeast strains present the highest level of HCDC activity within the Fermivin range, with respectively 100% for P21, 80% for VR5 and 65% for A33 and the highest HCDC of the Anchor yeast range are Exotics MOSAIC, Alchemy III and Alchemy IV.
According to some authors, the use of an enzyme with CE activity is not compulsory since tartaric esters of phenolic acids seem to be stable after alcoholic fermentation. But some others reported the liberation of free phenolic acid during ageing, which constitutes a risk of volatile phenol formation if there is contamination by Brettanomyces. So it is better to use this kind of enzyme to dramatically reduce the risk.
With a highly qualified team of experts in many fields, Oenobrands strives to offer winemakers’ novel and scientifically sound solutions, as well as to highlight the positive synergies between its products.
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