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

To explore a potential use for peanut skins as a functional food ingredient, milled skins were extracted with 70% ethanol and filtered to remove insoluble material; the soluble extract was 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.