Wine has to be preserved to maintain its organoleptic properties and microbial safety.
Sulfur dioxide (SO2) is a preservative widely used in winemaking due to its antioxidant properties, as well as its ability to eliminate the natural microorganisms (bacteria and yeasts) and pathogens. Also, it prevents browning reactions and colour loss during wine aging, fixing, for instance, the red colour of anthocyanins in red wines.
Despite all the advantages of SO2, the sulfites resulting from the addition of SO2 to wine have caused organoleptic changes in the final products and even allergic reactions in some consumers. Head-aches, nausea, abdominal pain, diarrhea, dermatitis, and breathing difficulties are just some symptoms observed in sulfite-sensitive individuals. In recognition of this sulfite hypersensitivity, the wine labels must have indication of the presence of sulfites, and the legislated maximum concentration of SO2 allowed in wines has been gradually reduced.
Wine label with indication of the presence of sulfites. Photo courtesy of Atlas Wine Co.
Owing to this problem, scientists have shown a great interest in the search for new healthier and safer alternatives to reduce or even eliminate the use of SO2 as a wine preservative. But what would be the ideal technology? It should be environmental friendly, simple, inexpensive and when applied to winemaking, it must not affect negatively the wine quality.
Several scientific articles have suggested some alternatives with potential to be used for wine conservation, namely:
the addition of chemical compounds (such as, bacteriocins, lysozyme, phenolic compounds, and others);
the use of some technologies like high pressure, pulsed electric fields, ultrasounds, and ultraviolet radiation.
Nevertheless, none of these procedures seems to be able to replace completely the use of SO2 by itself.
But is there any other solution on the market? Wait for the next post.
References:
Nunes, C., Maricato, É., Cunha, Â., Rocha, M.A.M., Santos, S., Ferreira, P., Silva, M.A.,Rodrigues, A., Amado, O., Coimbra, J., Silva, D., Moreira, A., Mendo, S., Lopes Da Silva, J.A., Pereira, E., Rocha, S.M., Coimbra, M.A. Chitosan-genipin film, a sustainable methodology for wine preservation. Green Chem. 18, 5331–5341. (2016) doi: 10.1039/c6gc01621a.
Santos, M.C., Nunes, C., Saraiva, J.A., Coimbra, M.A. Chemical and physical methodologies for the replacement/reduction of sulfur dioxide use during winemaking: review of their potentialities and limitations. Eur Food Res Technol. 234, 1-12. (2012) doi: 10.1007/s00217-011-1614-6.
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