All wines contain sulfites. Yeasts produce them naturally during fermentation. Almost all winemakers add additional sulfites during crush, pressing, and bottli

All wines contain sulfites. Yeasts produce them naturally during fermentation. Almost all winemakers add additional sulfites during crush, pressing, and bottling. There are "natural" wine makers who don't, but their wines still contain sulfites produced by the yeast during fermentation, though it's a much lower amount. And their wines usually end up faulty in some detectable way. What varies is labeling requirements for sulfite additions. California requires it, so it kind of spread because of that. But if the intended market for the wine doesn't require mentioning it, wine producers may not bother putting it on the label.