Prefermentative CO₂ saturation of grape must to obtaining white wines with low SO₂ content

Abstract

The objective this work has been study the possibility of partially or completely replacing sulphur in the winemaking of white wines through the use of the prefermentative saturation of musts with CO₂. Three types of wines were made from the same Airén and Chardonnay must and under the same conditions: Control wine, reduction of SO₂ in half and total reduction of SO₂.

No technologically important variations in the usual oenological parameters were observed in freshly bottled wines by saturating the musts with CO₂ and decreasing SO₂ doses. In terms of color, it should be noted that all wines of both varieties had similar values of luminosity and that the saturation of musts with CO₂ produced wines with more green tones and the decrease in doses of SO₂ with more yellow notes. In relation to volatile composition, the saturation of musts with CO₂ and the reduction of SO₂ doses produced wines with higher concentrations of compounds responsible for fruity and floral notes. At the sensory level, the results of volatile analysis were corroborated and both trained tasters and consumers positively valued the wines. Microbial stability and colour were monitored for 12 months, a normal marketing period for young wines, with the following conclusions obtained:

Signs of malolactic fermentation were observed in wines without SO₂. However, wines with low doses of SO₂ remained perfectly stable. With regard to color after 12 months the wines of both varieties evolve in a favorable way, a slightly more intense color, but no notes of oxidation are seen. Effective control of acetic acid bacteria over time has been proven as the volatile acidity of these wines is similar to that of control wines and does not increase the year of bottling.