Adjuvants and additives for the colloidal stabilization of red wines without the use of cold

Abstract

The presence of turbidity and precipitates in the bottle causes depreciation of wine by consumers. Colloidal instability is at the basis of these phenomena. The cold treatment is a technique widely used to stabilize wines, as regards both the tartaric and the colloidal precipitations. However, it is an energy-consuming technique. In view of a sustainable management of winery practices, the work aimed at evaluating the possibility of using some enological products for the colloidal stabilization of wines without cold treatment. 8 adjuvants (sodium and calcium bentonite, hot and cold soluble gelatin, chitosan, isinglass, PVI/PVP, carboxymethylcellulose) and 4 additives (kordofan gum, 2 different mannoproteins, a natural polysaccharide polymer) were compared. The trial was performed with a Barbera (2019) and a Montepulcianod'Abruzzo (2020) wines, stabilized against tartaric precipitations without cold, but with colloidal instability. Three days after the treatments the wines were racked, filtered (3 m) and bottled. After bottling and after 6 months of bottle aging, the wines were analyzed. Colloidal stability test (48 hours at 4°C) and shock test (1 and 7 days at 40 °C) were performed. As regards Barbera, the treatment with sodium bentonite (50 g/hL) or the addition of a mannoprotein (15 g/hL) allowed to stabilize the wine. For Montepulciano, having a higher colloidal instability than Barbera, the cold stabilization resulted necessary because no treatment was effective. All treatments had a modest impact on the color.