1. University ofArkansas
Arkansas Newswire
Researchers Design 'Green' Extraction Method for
Antioxidants in Grape Skins
Method usesgrape wasteproducts, pressurized water
Thursday, Sept.eni>er 08, 2011
FAYETTEVILLE, Ark. - University of
Arkansas researchers are taking grape
skins left from making wine andjujce and
using "green" processes to extract
powerful antioxidants that canbe used in
health products.
"The goalis toget a value-addedfood
supplement product," saidJerry King,
professor ofchemicalengineering at the
University ofArkansas. Beverages such
Luke Howard, Jerry King
as grapejuice and wine contain natural antioxidants, which have anti-inflammatory
properties when ingested. However, whilejuices andwine contain some ofthe
antioxidants, up to 50 percent remaininthe waste materialleft behindwhenthe skins,
stems and seeds get filtered away. "These are valuable components that don't go into
the juice or wine," King said.
Grape waste means business: The United States generates about 15 million tons of
grape waste eachyear, and most ofit currently ends up as compost or animalfeed.
Extracting products with potentialhealthbenefits from the waste has commercial
interest.
However, traditionalextraction methods use organic solvents, whichcanbe expensive,
toxicand difficult todispose. King andhis colleague, food science professor Luke
Howard, received $350,ooo over four years from the U.S. Department ofAgriculture
as part ofaninterdepartmental collaborationto employ a methodusing pressurized
water to extract the antioxidants. For the past four years, they have workedwith

2. graduate students Jeana Monrad and Keerthi Srinivas to optimize these extraction
methods using a technique called subcriticalwater processing.
To do this, scientists heat the water under pressure, which allows it to remainliquid at
high temperatures and act as an extraction solvent. They also used organic acids to
isolate certain types of antioxidants.
The researchers faced several challenges with this method, because natural
antioxidants can break down at high temperatures. They developed a process of
continuous extraction that allows for high flow rates to minimize antioxidant
degradation and maximize their breakdown.
The researchers created an 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.
Contacts:
Jerry King, professor, chemical engineering
College ofEngineering
479-575-3835, jwkin.g1@uark.edu Cmailto:jwkin~1@uark.edu)
Luke Howard, professor, food science
Dale Bumpers College ofAgricultural, Food and Lif
479-575-2978, lukeh@uark.edu Cmailto:lukeh@uark.edu)
Melissa Blouin, director ofscience and research communication
University Relations
479-575-3033, blouin@uark.edu (mailto:blouin@uark.edu)