What do vintners do with the grape skins after crush?
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Dear Dr. Vinny,
What do vintners do with the grape skins after crush?
—John, Georgia
Dear John,
The leftover grape skins, seeds and stems from winemaking are called “pomace.” You may have heard this term used in relation to the leftover bits of olives from olive oil production or apple remnants from apple juice.
Pomace is different from lees and sediment, which also refer to grape solids at different points in wine production. Sometimes pomace is a useful tool—there’s an Italian wine called ripasso that actually adds some pomace to its fermentation to increase a wine’s intensity.
When it comes to the leftover pomace, if it’s a large winery with a whole lot of pomace, there are some commercial ventures that recycle those solids. Pomace can be processed into all kinds of things: cream of tartar, distilled into spirits like grappa, ground into powdered tannin extract, used as food coloring or turned into animal feed. Grape seeds can be separated and pressed into grape seed oil. I’ve seen baking flour, cosmetics and spa treatments and scrubs made from grape pomace. I’ve even heard methane gas can be extracted from grape pomace, under the right conditions.
Smaller operations typically just add the pomace to their compost pile and use it as mulch. During harvest, you can see huge piles of pomace at wineries, often in dried cakes of wine-smelling solids.
—Dr. Vinny
