Purification and concentration of antioxidative dipeptides obtained from chicken extract and their application as functional food

Abstract

In Japan, about 150,000 tons of egg-laying hens are discarded annually because quality of their meet is low. In order to add further value to carcasses of the spent egg-laying hens and utilize them, an efficient purification and concentration process for functional dipeptides in chicken extract obtained from these carcasses was developed in this study by combining ion-exchange chromatography and nanofiltration (NF) treatment. The functional dipeptides, Anserine and Carnosine, consisting of β-alanine and L-histidine (ACmix), showed a basic property and could be adsorbed directly onto a cation exchange resin. The ACmix were completely separated from other chicken extract elements when the chicken extract was passed through the column packed with cation exchanger and the dipeptides were eluted from the column by using diluted alkaline solution. Major contaminated substances in the ACmix after ion-exchange chromatography were Na+, K+ and creatinine. A NF membrane could remove these contaminants and concentrate ACmix without any heat treatment. Based on the results of pilot scale experiments, a mathematical model which could express efficiency of a NF process was newly proposed. By using the mathematical model, an industrial scale NF process which could process 3.6 tons of carcasses in a day were designed, where minimum purify and yield of ACmix in the final product were set at 90% and 95%, respectively. The ACmix had an antioxidant activity specifically to hypochlorite radicals and markedly reduced an oxidative stress in normal human volunteers in combination with vitamin C and ferulic acid.