Alternative cold experiences for colloidal and color stabilization of red wines
Wines are hydroalcoholic solutions and also colloidal dispersions. Colloidal dispersions can remain stable over time and wines remain clear, or they can become unstable and cause aggregates to appear between colloids that can remain in suspension (turbid wines) or precipitate forming a deposit. In red wines, precipitation of colloids is one cause of loss of coloring matter.
To stabilize wines against colloidal precipitation, clarification treatments can be carried out to remove the compounds responsible for instability, or additives can be added that can act as protective colloids.
In extensive work carried out by Crea-Ve of Asti, the effect of certain clarification treatments and the addition of additives on the polyphenolic component, color and colloidal stability of wine during the first months of bottle storage was studied.
Eight clarifiers and four adjuvants were tested, and some interesting treatments were identified to achieve the goal of colloidal and color stability. Among the clarifying treatments, the most interesting results were obtained with Absolute Gold (95% montmorillonite sodium bentonite), with which colloidal stability was achieved and maintained even after one year of storage. It should be noted that the treatment did not cause technologically significant color loss.
Regarding additive treatments, the best results were obtained with Fender Color (mannoprotein), which acts as a protective colloid toward the coloring matter.
Finally, interesting results have also been obtained with the use of Délite (Kordofan gum arabic), which can be used to reinforce the action of Absolute Gold or Fender Color.
For more information, visit Dal Cin
Effect on colloidal stability of red wines of some subtractive treatments and additives
Antonella Bosso, CREA-VE, sede di Asti
Colloidal instability represents one of the causes of color loss in red wines. In this work, the effect of some subtractive interventions and additives on the colloidal stabilization of two red wines (Barbera and Montepulciano d’Abruzzo) that were stable against tartaric and protein precipitation was studied. Eight adjuvants and four additives were used. The wines after clarification or addition of the additives were filtered and bottled, and the bottles were stored in the dark at 20°C. Colloidal stability was assessed by measuring the increase in turbidity after storage for 48h at 4°C. The wines were then subjected to a shock test consisting of measuring turbidity before and after storage for 1 and 7 days at 40°C.
After treatments, all Barbera wine theses were clear; during storage there was a weak increase in turbidity in the teste thesis and cloudiness in the CMC thesis.
Treatment with sodium bentonite and the addition of mannoprotein2 stabilized Barbera wine against colloidal precipitation (test at 4°C for 48 h). Wines treated with sodium bentonite and mannoprotein2 were also the most stable in the shock test at 40°C.
Treatments with sodium bentonite, as well as the use of heat-soluble gelatin and the addition of mannoprotein2, and especially a natural polymer, have made it possible to reduce the degree of colloidal instability of Montepulciano d’Abruzzo wine, but not to achieve its stabilization.
In the case of Montepulciano d’Abruzzo, it is likely that the high polyphenolic concentration (4.8 g/L proanthocyanidins) is the cause of the strong instability. The Montepulciano wines, in fact, did not show any instability after storage at 40°C for 7 days; on the contrary, in the theses added additives, particularly mannoproteins and vegetable polymer, a reduction in turbidity is observed after storage at 40°C, as if the heating had acted by determining the rearrangement of the distribution of macromolecules in colloidal structures in favor of their stabilization.
Practical suggestions for preserving color and obtaining stable red wines
Maria Manara, Dal Cin s.p.a.
The colloidal stability of red wines involves various macromolecules such as proteins, polyphenols and polysaccharides whose interactions lead to aggregates subject, depending on the chemical and physical conditions of the medium, to form precipitates.
Noting that the presence of precipitates, turbidity or cloudiness in the bottle is not accepted for the vast majority of wines, research work has been initiated to identify solutions to achieve colloidal and color stability by reducing or eliminating the use of chilling.
The research, conducted in collaboration with Crea-Ve in Asti, considered both clarifying (subtractive) and refining (additive) treatments and identified some decidedly interesting adjuvants to achieve the stability objective.
Among the clarifying treatments, the most interesting results were obtained with Absolute Gold, a sodium bentonite with 95% montmorillonite, and with which colloidal stability was achieved in Barbera wine; stability maintained even after one year of storage. It should be noted that the treatment did not cause technologically significant color loss.
Regarding additive treatments, the best results were obtained with Fender Color, a polysaccharide from yeast that, by virtue of its chemical structure, acts as a protective colloid toward the coloring matter. In red wines with high colloidal instability, additive treatment with Fender Color may be more attractive than subtractive treatments for not stripping the wine of the protective colloids already naturally present.
Finally, interesting results have also been obtained with the use of Délite, a Senegal-type gum Arabic, which can be used to reinforce the action of Absolute Gold or Fender Color.
Recordings of the Dal Cin module held during Enoforum Italia 2021 May 18-20, 2021 in virtual format.
