Chuck Grimmett

“SO2 (sulphur dioxide) is a very reactive molecule that binds with different types of wine compounds (aldehydes, phenols, etc.) that play a role in forming a wine’s aroma. In that sense minimizing the usage of sulfites is a reasonable practice in winemaking. The efficiency of it however, depends very much on the wine’s pH due to the higher activity of the molecular form of sulfites. From the sensorial point of view, sulfites mask some of the effects of the oxidation because of how they bind quickly with aldehydes, as well as partially preventing oxidation because their redox potential. Another quite important aspect is related to the prevention of bacterial growth and yeast development.

When a wine has no sulfites added and passes through malolactic conversion, byproducts can occur after the transformation of all the malic acid as a consequence of existing residual bacteria. The result is considerable amounts of biogenic amines (histamine, cadaverine, putrescine, etc.) There are some people that are quite allergic to histamines for example which can result in adverse health effects.

What this means is that besides the known disadvantages of too much SO2 in wine, it’s also the case that with no sulfites at all, similar health problems may occur to those susceptible in addition to potential spoilage of the wine, especially in high pH wines.