Last year, California and Washington wineries crushed around 4.5 million tons of wine grapes. That's an awful lot of skins, seeds and stems left over—something like 1.5 million tons. When it comes to reducing waste, many wineries are cutting the use of electricity, fuel, water and packaging. One thing I don't hear a lot about when covering sustainability efforts is post-harvest waste: pomace. Maybe a big, squishy mass of pulp sounds less sexy than an elegant, energy-efficient building, but pomace is no less ripe for innovation.
Often, pomace goes into compost or animal feed. But what if a winery could sell its pomace for higher-value products—healthy, "green" ones? After all, pomace is packed with all those promising polyphenols that end up in wine, plus fiber.
That was the thinking of Yanyun Zhao, a professor in Oregon State University's department of food science and technology. She and other researchers there have been turning pomace into things like antioxidant-rich flour for baked goods, biodegradable containers and nutritious methods to preserve fruit, yogurt and salad dressing.
How about a healthier brownie? In their latest research, by drying and grinding pomace, Zhao and her students turned fiber extracts into gluten-free powders. They were able to replace up to 15 percent of the flour—"that's a significant substitution," said Zhao—in muffins and brownies with their antioxidant- and fiber-rich substance. (Now they're seeking the right mix for bread.) Formal taste tests are set for April.
Wish you could get some of the same benefits from your Thousand Island dressing as you do from the salad it's on? Just add a touch of red wine pomace powder for antioxidant-rich fiber. That bottle will also stay fresh longer because the phenolic compounds slow the deterioration of lipids, according to a study published this year. Same goes for yogurt. With a 1 percent addition, testers still liked the taste and texture.
It's not as if pomace hasn't already been put to other uses. The seeds are used to produce grapeseed oil for cooking. Grapeseed polyphenol extracts are sold for nutritional supplements and are being tested to treat medical conditions. Pomace extracts go into cosmetics, like the Caudalie skin-care line from France and the newer Esdor brand from Spain's Matarromera winery group, which built its own polyphenol extraction plant. (It uses 1,482 kilograms of skins to make 1 kilogram of extract.)
So why do we need even more uses for pomace? OSU is hardly alone in this line of research. "Even with those applications, it's not all used up, and we're not using all of what's in the pomace," said Zhao, who aims for "100 percent utilization."
But, I wondered, isn't compost the most logical, efficient use of all? What comes from the land goes back to the land, little transportation or energy required. Surely, a sustainable, organic or biodynamic estate can use up all its own pomace?
"We never have extra. As a matter of fact, I ask neighboring vineyards to bring me more," confirmed Barbara Shinn of Shinn Estate on Long Island. However, "using pomace for other products could be a great solution for a winery that does not own vineyards. … Pomace is always an issue if a winery has nowhere to take it other than the town dump."
The next step is for OSU to find companies—possibly some major wine corporations—interested in commercializing these new products. Zhao has plenty of other ideas.
You know those waxy coatings on supermarket apples, oranges and cucumbers? They're there to keep microbes out and moisture in. Edible film—made from pectin, cellulose and sugars extracted from grape skins—can serve a similar purpose, plus provide an extra antioxidant boost, said Zhao, as demonstrated in research published in 2011.
Zhao ticked off other possibilities for the naturally pigmented, antibacterial films, which could be applied like a coating or look like plastic wrap: sticky candies and "beautiful, bright, colorful wrapping" for kids' snacks.
Or the researchers could work with nurseries to customize plantable pots, molded from a pomace biocomposite fiberboard, to match different plants' needs. In a 2010 study, red grape skins produced stronger, more water-resistant board. White grape skins—rich in soluble sugar, a plasticizer—produced more flexible board that biodegrades more quickly.
Maybe the day isn't far off when we can have a truly grape-immersive experience in wine country. Start your morning off with a pomace muffin. Then visit a wine estate where the vineyard is fertilized with its own grapes. Enjoy a grape-preserved salad in the picnic area after purchasing a case of wine, the bottles carefully protected by pomace fiberboard inserts. After a long, wine-soaked dinner of steak from cattle fed a pomace supplement, wake up and apply a grapeseed skin cream to recover from indulging. Repeat. After all, recycling is good.
What uses for pomace do you find most appealing?