Occurrence of red pigment-forming substances during autoxidation of lipids.

Abstract

Occurrence and discoloration property of red pigment-forming substances (RPSs) produced during autoxidation of polyenoic acids were investigated. Autoxidezed lipids (methy1 linolenate, methyl arachidonate, linseed oil and tuna liver oil) were separated on Sephadex LH-20 with CHCl3/MeOH (1/1, v/v), and the pooled RPS-fractions were further separated by TLC. Two to four or more than four spors on the TLC plate turned into reddish-color by spraying with α-amino acids, but not by spraying with aliphatic amines, ammonium chloride, and purine and pyrimidine bases in neutral solutions. Proline and hydroxyproline developed a golden yellow color immediately. The purified RPS derived from linolenate had an absorption maximum at 226-227 nm in EtOH and in MeOH/water (2/1, v/v), and 241 nm inchloroform. By the reaction with amino acids, the absorption at λmax 226-227 nm decreased with the increase taking place at λmax 510-520 nm which was attributed to the formation of red pigment.