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ARS Home » Southeast Area » Raleigh, North Carolina » Market Quality and Handling Research » Research » Publications at this Location » Publication #238473
Title: Chemistry and Biochemstry of Peanut Skins. Implications of Utilization

Author
item Dean, Lisa
item Davis, Jack
item LEWIS, WANIDA
item Sanders, Timothy

Submitted to: American Peanut Research and Education Society Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 7/14/2009
Publication Date: 7/17/2009
Citation: Dean, L.L., Davis, J.P., Lewis, W.E., Sanders, T.H. 2009. Chemistry and Biochemstry of Peanut Skins. Implications of Utilization. American Peanut Research and Education Society Abstracts.

Interpretive Summary: The problem of material from peanut shelling is in part from the left over skins. They have very little value as animal feed and are often sent to landfills for disposal. Peanut skins from an NC peanut processing plant were extracted using several different mixtures of organic solvents and water and were tested for their content of chemical compounds called phenols and for their activity as chemical antioxidants using the Oxygen Radical Absorbance Capacity or ORAC test. It was found that a mixture of acetone and water produced the highest values in the tests. The peanut skin extract was evaluated using Liquid Chromatography (LC) combined with Time of Flight Mass Spectrometry (TOFMS). The chemical compounds identified were those called phenols in particular catechins which are known to have bitter flavors and procyandins which have red colors. If peanut skins are extracted with solvents in this manner, they can be cleaned to reduce the bulk and to concentrate the phenolics compounds to make them suitable to be used in foods.

Technical Abstract: Peanut shelling plants in the US produce thousands of tons of peanut skins each year. Currently, this material is considered a waste product with limited end uses and no real monetary value. Peanut skins were obtained from a regional peanut processor and subjected to a several types of solvent extraction. The extracts were analyzed for their total phenolic compound content using the Folin-Ciocalteu assay and their antioxidant activity using the ORAC assay. Solvent composition was found to affect the resulting ORAC values of the extracts. It is thought that more polar solvent mixtures remove more of the phenolic type compounds which are known for their activity as antioxidants involving hydrogen atom transfer, therefore the total phenolic levels and the ORAC values usually correlate well. The extract giving the highest ORAC value (acetone/water) was subjected to LC-TOFMS to determine the compounds present. It was found that the compounds extracted were primarily phenolics such as catechins and procyandins. Solvent extraction can be used as method of isolating specific types of compounds and to clean large quantities of waste peanut skins to make them more acceptable for food ingredient use.