Studies on the Metal-Protein Complex. VII.

Abstract

In the previous papers, the authors reported and made clear the easy formation of metal-melanoidin complex in system of aqueous solution.In this paper, the relationship between the binding ability of melanoidin (M) and metal in oil, or M-metal complex on the rancidification of oil was investigated.Then the M (prepared from a mixture of glycine and D-xylose by heating at 100°C for 5 hour) was reacted at usual and high temperatures with copper sulfate or ferrous chloridein oil.From the experimental results, it was found that the formation of M-metal complex and the amount of M-metal complex increased with the longer reaction time in the system of oil.For the antioxidative effect of these materials it was found that the rancidity of lard was highest in the cases of M and metal mixture and M-metal complex, but in the case of soybean oil the peroxide value remained low.Consequently, it was recognized that M acted as a potent synergist of antioxidants as well as tocopherol and BHA under certain conditions.