Characterization of high Fischer ratio oligopeptides produced from casein

• Enzymatic hydrolysis was achieved via alcalase® and flavorzyme®. • Adsorption activated carbon was optimized as AK-220. • Casein Fischer ratio was significantly elevated from 2.17 to 9.87. High Fischer ratio oligopeptides mixture is a mixed peptide system which possess many beneficial effects to the human body. Casein, a milk protein, was used as feedstock to prepare high Fischer ratio oligopeptides via enzymatic hydrolysis, adsorption and purification. Gel electrophoresis, densitometric analysis, amino acid assay and molecular weight measurement were used to visualize and quantify the prepared peptides. Casein, with Fischer ratio of 2.17, was subjected to hydrolysis by alcalase® (2.4 AU/g, pH 8.5, temperature 55 °C, enzymolysis time 2 hours) and flavorzyme® (3.4 AU/g, temperature 50 °C,enzyme amount 120 μL, enzymolysis time 3 hours), followed via AK-220 activated carbon adsorption (carbon-hydrolysate ratio: 1:10, adsorption time 3 hours, pH 8.0, temperature 55 °C) and 3 KDa membrane ultrafiltration. In conclusion, the processing parameters for alcalase® / flavorzyme® and AK-220 activated carbon helped to obtain oligopeptides with Fischer ratio 9.87 which is significantly higher than feedstock casein F value ( p <0.05) and could potentially be used as food supplement to enhance product nutritional property.