Waste product from winemaking full of antioxidants
By MATEUSZ PERKOWSKI
Every year, vintner Joe Dobbes of Dundee, Ore., is deluged with 350 tons of grape pomace -- the skins and seeds leftover from winemaking.
Dobbes must spend thousands of dollars for his garbage company to collect the material, which is then composted.
"We pay them to take it away and then sell it," he said. "I think it's a good deal for them."
Though pomace is often a liability for Dobbes and other winemakers, a researcher at Oregon State University thinks the substance may yet prove to be an asset.
Food science professor Yanyun Zhao has found that pomace is loaded with beneficial dietary fiber and antioxidants that could turn the byproduct into a commercially viable food supplement.
Pomace, if left to its own devices, will spoil within days. Zhao is studying the most economical and efficient ways to dry the material without destroying the healthful compounds it contains.
Freeze-drying does the least damage but is also the most expensive, she said. Using a hot air dryer at relatively low temperatures -- about 100-120 degrees Fahrenheit -- appears to be the most efficient.
The dried material can then be crushed into a powder and used as a food ingredient.
Zhao is researching the optimum rates at which the pomace can be used without affecting the flavor of the final product.
For example, pomace can comprise about 10 percent of the ingredients of a muffin, but probably less than 3 percent for yogurt, she said.
Another potential application for pomace is as a packaging material. Polymers can be extracted from the substance relatively easily and used to make an edible film.
As an added benefit, this process can be performed with raw, moist pomace, eliminating the need to dry the material.
So far, Zhao hasn't identified a winery willing to invest in such value-added applications for pomace.
She said it may be more realistic for a dedicated food processor to undertake such a project, sparing wineries the added expense and expertise.
Dobbes said that wineries may be reluctant to finance such a venture, particularly if they are hesitant about their ability to market the finished product.
Even so, the trend toward more environmentally sustainable winemaking is conducive to higher-value uses of pomace, which many wineries recognize as an underutilized byproduct, Dobbes said.
"I think it's a real lost opportunity for all this biomatter," he said.