Fractionation and characterization of a protein fraction producing off-flavor volatiles in peanut seed

A high molecular weight protein fraction (peak I) obtained from peanut (Arachis hypogaea L. cv. Florunner) seed was fractionated using ammonium sulfate and methanol to isolate the protein(s) involved in off-flavor volatile production during roasting of peanut. The results showed that maximum off-flavor volatile-producing activity is associated with the 20% ammonium sulfate precipitate and 85% methanol-soluble fraction of this protein. Peak I protein was found to be lipoprotein in nature and is rich in oleic acid (63%) and palmetic acid (8%). Furthermore, the 85% methanol-soluble fraction of peak I protein was found to contain a mixture of low molecular weight proteins and major amounts of glycine (11%), alanine (11%), proline (15%), phenylalanine (8%), and lysine (8%).