(MercuryNews) - As consumers have shown more interest in what's in their food, some are extending that to wine. What's in that bottle anyway?

At its most basic, wine contains grapes and yeast; the latter converts the sugar in the grapes into alcohol. In most cases, at least some sulfur dioxide is added as a preservative. But there are lots of additives that are permitted, a list that includes everything from water to tartaric acid to brighten up the wine, cultured yeast to ferment the wine (though some winemakers rely solely on the ambient yeast from the grapes and in the winery), coloring agents made from grape concentrate, and chemicals to kill objectionable microbes. Some are benign; some less so.

labeling is one solution, but so far, it hasn't been widely embraced by wine producers. There's the ubiquitous "contains sulfites" statement on any wine with added sulfur, but not much else. Ridge Vineyards in Cupertino recently unveiled ingredient labeling on its 2011 wines. On the Ridge website -- www.ridgewine.com -- CEO Paul Draper notes that the winery is listing ingredients to demonstrate that additives and invasive processes are not necessary to make fine wine.

Ridge joins Santa Cruz's Bonny Doon Vineyard, which began including ingredients on its back labels for the 2006 reds and 2007 whites. Winery founder Randall Grahm told me at the time that such labeling would help keep the winery