Browning Reaction of Oxidized Peanut Oil with Amino Acids on Filter Paper

Abstract

Peanut oil and glycine or N-acetylglycine were adsorbed on filter papers(Whatman No.42, 11-cm in diameter)and the filter papers were incubated at 50°C with 15-20% relative humidity in the dark. Changes in peroxide value(POV)of peanut oil alone and with glycine or N-acetylglycine were similar and no browning was observed at the initial 25 days of incubation. However, POV increased and browning occurred in peanut oil with glycine thereafter. Almost no browning was observed in peanut oil alone or with N-acetylglycine in 60 days. Autoxidation proceeded more rapidly in Florisil-treated peanut oil than in peanut oil due to the removal of tocopherols. The intensity of browning became much stronger in Florisil-treated peanut oil than in peanut oil by the addition of glycine. When Florisil-treated peanut oil was incubated with amino acids for 5 days, browning was strongest with lysine, followed by proline. POV in all the samples increased rapidly within 2 days and then decreased with increasing incubation time. POV was highest in Florisil-treated peanut oil alone and lowest with proline. In Florisil-treated peanut oil, the formation of carbonyls was slightly higher in peanut oil alone or with N-acetylglycine than with amino acids.