Experiments with alternatives to cold for color stabilization of red wines
Effect on the color of red wines of different subtractive treatments and additives
Antonella BOSSO, CRA-Centro di Ricerca per l’Enologia, Asti, Italy
Colloidal instability is one of the causes of color loss in red wines. In this work, the effect of some subtractive and additive interventions on the colloidal stabilization of two red wines, stable against tartaric and protein precipitations, was studied.
Eight adjuvants and four additives were studied. After stabilization treatment, colloidal stability was evaluated by measuring the increase in turbidity after storage for 48 hours at 4°C, and after a shock test consisting of measuring turbidity before and after storage 1 and 7 days at 40°C.
In this presentation Antonella Bosso will describe the interesting results obtained and the possible mechanisms that explain the different behaviors observed.
Practical proposals to preserve color and obtain stable red wines
Maria MANARA, R&D Manager, Dal Cin Spa., Italy
The colloidal stability of red wines involves various macromolecules such as proteins, polyphenols and polysaccharides whose interactions give rise to aggregates that, depending on the physicochemical conditions of the medium, can form precipitates.
Considering that the presence of precipitates or turbidity in the bottle is not acceptable 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 cold.
The research, carried out in collaboration with Crea-Ve of Asti, took into account both clarification (subtractive) and refining (additive) treatments and allowed the identification of some very interesting adjuvants to achieve the stability objective.
Among the fining treatments, the most interesting results were obtained with Absolute Gold, a sodium bentonite with 95% montmorillonite, which achieved colloidal stability in Barbera wine; stability maintained even after one year of storage. It should be noted that the treatment did not cause a technologically significant loss of color.
As regards additive treatments, the best results have been obtained with Fender Color, a yeast polysaccharide which, due to its chemical structure, acts as a protective colloid for the coloring matter. In red wines with high colloidal instability, the additive treatment with Fender Color can be more interesting than subtractive treatments so as not to deprive the wine of the protective colloids already naturally present.
Finally, interesting results were also obtained with the use of Délite, a Senegal-type gum Arabic, which can be used to enhance the action of Absolute Gold or Fender Color.
