LAUSR

Abstract The aims of this study were to determine the proximate and amino acid compositions, mineral content, and fatty acid and proanthocyanidins (PAC) profiles of peanut skins (PS) from three varieties of peanuts. Proximate composition showed that PS had a moisture content from 9.71 to 11.0%, ash content from 2.07 to 2.13%, fat content from 9.59 to 10.2%, protein content from 8.88 to 12.7%, and dietary fiber from 38.8 to 42.8%. The amino acid composition indicated that lysine and phenylalanine, glycine, and glutamine were the predominant amino acids in PS. Mineral content indicated that potassium was the main macro-element in PS. Palmitic, oleic, and linoleic acids were the predominant fatty acids in PS. Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) of PAC showed that the predominant masses were typical of (epi)catechin monomers with “A-type” interflavan bonds. Deconvolution of overlapping isotope patterns observed with MALDI-TOF MS indicates that in all PS, 95 % of the PAC oligomers contain one or more A-type bonds. These results indicate that PS may be used as functional ingredients to improve profitability of the peanut industries through the use of a low-value by-product. To the best of our knowledge, this is the first study providing a chemical evaluation and comparison of PS from three varieties of peanuts.