Sulphur dioxide (SO2) is used in winemaking as a preservative. In its "free" form, it is a powerful antioxidant and inhibits or kills unwanted organisms in your must. While it is possible to produce sound, healthy wines without the use of added SO2, it is a technical challenge beyond the basic skills of conventional winemaking.
The WineCoach will make SO2 addition recommendations at various points during the winemaking process. To research the results of various additions, please use the sulfite calculator.
Many producers of organic wines rely on the beneficial properties of the yeast lees to protect their wines from oxidative damage during ageing and these wines are often highly filtered to enhance the stability in the bottle. Such wines are also often bottled with low levels of carbonation because dissolved SO2 has protective qualities. Another technique is the use of ascorbic acid (vitamin C) in place of SO2. This substitution is not direct and should be studied before being applied.
Notes from the winemaker: Some WinePod users are going to want to make "organic" wines without the use of SO2. While it is possible to do so, (assuming a source of organic grapes, which ProVina does not currently supply) I don't recommend it for a number of reasons. Foremost is the chance for spoilage organisms to ruin the wine, which SO2 use mitigates. But even absent spoilage it is my firmly held opinion, based on long consulting experience, that wines made without SO2 are simply not as palatable as wines made with. That said, I don't want to discourage potential users from experimenting. I do think those who won't use SO2 should examine their reasons, and ask themselves if they might have other chemical sensitivities that could impact how they use the Pod.