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Antioxidants in waste products of Virginia agriculture: peanuts and grapes and utilization for nutraceutical applications
MILES associate Paul Sarnoski analyzing antioxidants in peanut extracts
Achievement/Results
NSF MILES-IGERT trainee Kevin Holland (a recent graduate, December 2009) and associate Paul Sarnoski have been working with NSF funded researchers Dr. Sean O’Keefe in the Food Science and Technology Department and Dr. Kumar Mallikarjunan in the Biological Systems Engineering Department at Virginia Tech on developing methods for using peanut byproducts (skins, roots) and grape byproducts (seeds, pomace) to be used as natural antioxidants. Kevin Holland and Dr. Sean O’Keefe have been investigating the antioxidant activity of peanut skin extracts. They hope that peanut skin extract will replace synthetic antioxidants currently found in food and find an application for an underutilized waste product.
They compared the antioxidant activity of peanut skin extract with that of grape seed extract using the oxygen radical absorbance capacity (ORAC) assay. Grape seed extract has been investigated thoroughly and is currently commercialized as an antioxidant additive in food and also as a health supplement. Holland and O’Keefe found that peanut skin extracts prepared various ways and a commercial grape seed extract have similar antioxidant activities. This research proves that peanut skin extract may have commercial value as an antioxidant.
Kevin Holland also studied antioxidants in peanut roots. By finding applications for peanut roots, it may be possible to increase the economic value of these waste materials. The peanut root extracts may also have applications in food products to prolong the shelf life and preserve the taste of foods. Peanut root extracts may also inhibit protein oxidation. Protein oxidation is believed to cause diseases such as Alzheimer’s, atherosclerosis, and has been linked with the aging process. Potent antioxidant fractions from the peanut root extracts may be used as dietary supplements to prevent or slow down disease progression or age-related illnesses.
Paul Sarnoski is investigating the ability of polyphenolic compounds in Virginia waste products from peanuts and grapes on inhibition of enzymes related to glycemic control. Solvent extracts of peanut skins and a multistep solvent extraction process to yield oligiomeric procyanidin (OPC) extracts. These extracts were found to be inhibitory towards three types of yeasts that are commonly responsible for spoilage of juice products. The OPC extract that exhibited the highest inhibitory effect, and was chosen for fractionation to find the specific compounds that is responsible for inhibitory effect. Fractionation was conducted by means of a silica or size exclusion high performance liquid chromatography (HPLC) column. Fractions were then subjected to a yeast growth curve assay to determine the active (inhibitory) fractions. The fractions were then characterized by liquid chromatography- mass spectrometry (LC-MS). Oligomers and polymers of catechin, a compound widely found in teas, were found to be responsible for inhibitory activity towards yeasts. These compounds had the most inhibitory effect in an apple juice type medium and in the traditional yeast growing medium of dextrose broth. Both the yeast growth curve assay and the traditional plate count method yielded similar results.
Address Goals
Maximizing the value of underutilized crops in Virginia is crucial for the success of farmers and growers in Virginia. Two important commodities in Virginia agriculture are peanuts and grapes. Finding applications for peanut and grape extracts, it may be possible to increase the economic value of these waste materials. The extracts may also have applications in food products to prolong the shelf life and preserve the taste of foods. Peanut and grape extracts may also be associated with prevention of diseases such as diabetes, Alzheimer’s, atherosclerosis, as well as retarding the aging process. Potent antioxidant fractions from these extracts may be used as dietary supplements to prevent or slow down disease progression or age-related illnesses. Antioxidants can assist in achieving oxidative balance for diabetics. Research suggests that the polyphenol polymers can play a direct role in the regulation of diabetes.
