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

Izquierdo Cañas P.M. ¹, Guri Baiget S.^2*, García Romero E.³, Cejudo Martín de Almagro V.⁴, Mallen Pomes J.⁵

¹ Instituto Regional de Investigación y Desarrollo Agroalimentario y Forestal de Castilla-La Mancha (IRIAF), IVICAM, Ctra. Albacete s/n, 13700 Tomelloso, Ciudad Real, Spain
² Carburos Metálicos S. A.- Air Products Group. Avda de la Fama 1, 08940 Cornellà de Llobregat, Barcelona, Spain
³ Instituto Regional de Investigación y Desarrollo Agroalimentario y Forestal de Castilla-La Mancha (IRIAF), IVICAM, Ctra. Albacete s/n, 13700 Tomelloso, Ciudad Real, Spain
⁴ Carburos Metálicos S. A.-Air Products Group. Avda de la Fama 1, 08940 Cornellà de Llobregat, Barcelona, Spain
⁵ Carburos Metálicos S. A.-Air Products Group. Avda de la Fama 1, 08940 Cornellà de Llobregat, Barcelona, Spain

* Corresponding author: guribas@carburos.com

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Introduction

Sulphur dioxide (SO₂) has a significant importance in Oenology because of its antioxidant and antibacterial properties (1, 2). From the sensorial point of view, SO₂ can give unpleasant flavors and odors to wine (3) and also the presence of sulfites in wines can lead to pseudo-allergic reactions in some people (4). That's why the international Organization of Vine and Wine (OIV) has reduced the maximum limits of the total SO₂ in wines.

The aim of this work is to study the possibility of replacing SO₂ partially or totally, by saturating the must with CO₂.

Material and methods

Three types of wines were made from the same Airén and Chardonnay must and under the same conditions: Control wine (A= 0% CO₂-50 mg/L SO₂), reduction of SO₂ in half (B= 100% CO₂-25 mg/L SO₂) and total reduction of SO₂ (C= 100% CO₂-0 mg/L SO₂). For obtaining wines B and C the must was saturated with CO₂. The equipment used to achieve CO₂ saturation at atmospheric pressure was an Inyecvin (Carburos metálicos), which has a porous diffuser that helps the diffusion of CO₂ into the must.  

The oenological parameters of all wines were analyzed according to the official methods of the OIV, its volatile composition by GC-MS and finally were evaluated sensory by consumers and expert tasters.

Results

By saturating the musts with CO₂ and decreasing doses of SO_2, the alcoholic fermentation starts earlier and it occurs more slowly which offers an advantage for the desirable formation and retention of aromas.

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 (Table 1).

Table 1: Basic oenological parameters of bottled Airén and Chardonnay wines

In terms of colour, 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 (Figure 1).

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 (Figure 2 I). At the sensory level, the results of volatile analysis were corroborated and both trained tasters and consumers positively valued the wines (Figure 2 II).

Figure 1: Color of Airén must and wines at different steps: Before racking, after racking, end alcoholic fermentation, bottled wines. 

Figure 2: Amount of OAV of the different families of aroma and sensory analysis of Airén and Chardonnay wines.

Microbiological stability and colour were monitored for 12 months (Table 2), a normal marketing period for young wines, with the following conclusions obtained: Signs of malolactic fermentation were observed in wines without SO₂ (C). However, wines with low doses of SO₂ (B) remained perfectly stable.

Table 2: Microbiological and colour stability of Airén and Chardonnay wines 12 months after bottling

With regard to colour 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.

Conclusions

The results presented in this study provide useful information for the wine sector, as CO₂ saturation of grape must during the prefermentative phase could be an alternative additive for reducing doses of SO₂ in white wines, providing stable wines over time with unique aromatic profiles.

References

Garde-Cerdán, T., Jarauta, I., Salinas, M.R., & Ancín-Azpilicueta, C. (2008). Comparative study of the volatile composition in wines obtained from traditional vinification and from the Ganimede method. Journal of the Science of Food and Agriculture, 88, 1777-1785.

Izquierdo-Cañas, P.M., García-Romero, E., Huertas-Nebreda, B., & Gómez-Alonso, S. (2012). Colloidal silver complex as alternative to sulphur dioxide in winemaking. Food Control, 23, 73–81.

Ribereau-Gayon, P., Dubourdieu, D., Doneche, B., & Lonvaud, A. (2006). Handbook of enology: The microbiology of wine and vinifications, (2nd ed.), Vol 1, Wiley, Chichester.

Santos, M. C., Nunes, C., Saraiva, J.A., & Coimbra, M.A. (2012). Chemical and physical methodologies for the replacement/reduction of sulfur dioxide use during winemaking: review of their potentialities and limitations. European Food Research and Technology, 234, 1–12.