Abstract
In the previous papers, the authors reported and made clear the easy formation of melanoidin-metal complex in aqueous solution and oil. As for the antioxidative effect of these materials, it was found that the rancidity of lard was the highest in the case of melanoidin (M) -metal mixture or M-metal complex. In this paper, the relationship between the binding ability of water soluble browning materials of miso (MB) with metal, and the effects of MB, tocopherol (Toc), metal and the mixture of these on the rancidification of oil were investigated. MB were prepared from water soluble browning materials in miso by Sephadex G 25 and four colored components were fractionated by DEAE-Cellulose column chromatography. MB and four fractionated materials was reacted at 50°C with some metals. From the experimental results, it was found that MB-metal complex was formed like melanoidin (M, prepared from a mixture of glycine and D-xylose by heating at 100°C for 5hr) -metal complex and the amount of MB-metal complex increased with the reaction time in aqueous solution. MB showed some antioxid ative activity, and the higher the added contents of MB, the larger the antioxidative effect in the lard was. It was also found that the rancidity of oil was seriously effected by metal and metal-Toc mixture, but in the case of MB-Toc-metal mixture, the peroxide value remained low.
