ARS | Publication request: Value-Added Processing of Peanut Skins: Antioxidant Capacity, Total Phenolics, and Procyanidin Content of Spray Dried Extracts

Submitted to: Journal of Agricultural and Food Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: October 10, 2012
Publication Date: October 10, 2012
Repository URL: http://pubs.acs.org/JAFC
Citation: Constanza, K.E., White, B.L., Davis, J.P., Sanders, T.H., Dean, L.L. 2012. Value-Added Processing of Peanut Skins: Antioxidant Capacity, Total Phenolics, and Procyanidin Content of Spray Dried Extracts. Journal of Agricultural and Food Chemistry. Vol 60, 10776-10783.

Interpretive Summary: The chemical composition of peanut skins includes many compounds that have antioxidant activity. The peanut industry produces hundreds of tons of this material each year, mostly at blanching plants. This material has very low economic value as the use in animal feed is limited. This study examined the feasibility of removing the compounds that are phenolic in nature and capturing them by spray drying to make powders that would be high in antioxidant activity. These powders would then be of higher value for possible nutraceutical uses. The remaining material after extraction would be low in bitter tasting phenolics and thus more palatable to animals, increasing its value as an animal feed ingredient that has levels of fat, protein and crude fiber close to that of the original skin material.

Technical Abstract: To explore a potential use for peanut skins as a functional food ingredient, milled skins were extracted with 70% ethanol, separated into a soluble extract and insoluble material by filtration, and spray dried with or without the addition of maltodextrin. Peanut skin extracts had high levels of procyanidin oligomers (DP2-DP4) but low levels of monomeric flavan-3-ols and polymers. The addition of maltodextrin during spray drying resulted in the formation of unknown polymeric compounds. Spray drying also increased the proportion of flavan-3-ols and DP2 procyanidins in the extracts while decreasing larger procyanidins. Spray dried powders had higher antioxidant capacity and total phenolics and increased solubility compared to milled skins. These data suggest that spray dried peanut skin extracts may be a good source of natural antioxidants. Additionally, the insoluble material produced during the process may have increased value for use in animal feed due to enrichment of protein and removal of phenolic compounds during extraction.