Chapter 18

Sulfur Dioxide Use in Winemaking

Alternatives to Sulfur Dioxide in Wine Production

The use of sulfur dioxide as wine additive is able to ensure both antioxidant protection and microbiological stability. In spite of these undeniable advantages, the presence of sulfur dioxide in wine has raised concerns about potential adverse on sensitive individuals from headaches, dermatitis, abdominal pain, diarrhea, asthma, and bronchoconstriction. In the light of this, several alternatives are used either as a substitute or replacement of sulfur dioxide in wine. Even though many of the alternatives to sulfur dioxide have demonstrated good efficacy, no other additive can deliver the efficacy and broad spectrum of action as sulfur dioxide (both antioxidant and antimicrobial), therefore the alternative methods should be considered a complement to sulfur dioxide in low-sulfite winemaking, rather than being seen as its substitutes. Most countries require a sulfite declaration statement on labels of wine that informs the consumer that the wine contains sulfites or sulfiting agents.

Ascorbic Acid

Ascorbic acid or vitamin C has long been used in the wine industry as an anti-oxidant, especially in white wines, given it ability to rapidly remove molecular oxygen from juice or wine. In contrast to sulfur dioxide, ascorbic acid is able to efficiently scavenge DO. This feature provides a direct removal of DO that is not ascribed to sulfur dioxide, which is instead known to act indirectly by reversing phenol oxidation processes.

Sorbic Acid

Sorbic acid has a broad-spectrum activity, mainly against yeast and molds (Section 13.1). It's action against bacteria appears to be selective. At concentrations used in wine it does not seem to prevent spoilage from either acetic or lactic acid bacteria. Because sorbic acid is relatively insoluble in water, the additive is usually sold as a salt (potassium sorbate, C6H7KO2), which is readily soluble.

Dimethyl Decarbonate

Dimethyl decarbonate (DMDC), also known as Velcorin, is used in place of sorbic acid as a yeast inhibitor and can also be used to decrease the amount of sulfur dioxide in wines. Dimethyl decarbonate has proved effective not only on fermentation yeasts, but also on those responsible for contamination Brettanomyces, as well as, to a lesser extent, bacteria. It is especially useful with high-quality wines, which are stored in barrels for many months and even years if there is a large risk of attack by Brettanomyces

Lysozyme

Lysozyme is a protein derived from egg whites used by winemakers to control the growth of gram-positive spoilage bacteria, such as lactic bacteria in wine. In juices, must, and wines, the main gram-positive bacteria are lactic acid bacteria (Pediococcus, Lactobacillus, and Oenococcus). Lysozyme cannot replace sulfur dioxide because it will not prevent infections by other spoilage organisms such as Acetobacter or Brettanomyces.

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