New Method for Extracting Antioxidants from Grape Waste

FAYETTEVILLE, Ark.Researchers at the University of Arkansas have discovered an environmentally friendly method to extract antioxidants from grape waste for use in other healthy food products. The findings suggest the process may one day be used to create healthy food supplements from the 15 million tons of grape waste generated in the United States alone.

The goal is to get a value-added food supplement product," said Jerry King, professor of chemical engineering at the University of Arkansas. Beverages such as grape juice and wine contain natural antioxidants, which have anti-inflammatory properties when ingested. However, while juices and wine contain some of the antioxidants, up to 50% remain in the waste material left behind when the skins, stems and seeds get filtered away.These are valuable components that dont go into the juice or wine."

The researchers received a $350,000 USDA grant to investigate alternatives to traditional extraction methods that use organic solvents, which can be expensive, toxic and difficult to dispose.

The team utilized a subcritical water processing method that used pressurized water to extract the antioxidants. Water is heated under pressure, which allows it to remain liquid at high temperatures and act as an extraction solvent. They also used organic acids to isolate certain types of antioxidants. Because natural antioxidants can break down at high temperatures, the researchers developed a process of continuous extraction that allows for high flow rates to minimize antioxidant degradation and maximize their breakdown.

The extraction method that not only increases the efficiency of extraction over ethanol alone, but also produces antioxidant compounds that are smaller in size, which are more effectively adsorbed by the body.