After pressing grapes, about 20 percent is not used in the fermentation process. That byproduct is called grape marc, also known as pomace, which includes stems, seeds and skins. In 2009, Peggy Furth and Barbara Banke, co-founders of WindRacer Wines, a Sonoma County, California company specializing in Chardonnay and Pinot Noir, had the idea to use Chardonnay marc as an ingredient in food. Collaborating with research scientists for many years, in 2021 they introduced Vine to Bar dark chocolate, the first vintner to upcycle grape marc into a consumer product.