Application of the Plackett-Burman design to determine the main factors affecting the anti-oxidative activity of goat's milk casein hydrolyzed by Alcalase and papain.

BACKGROUND: Antioxidant peptides can scavenge excessive free radicals produced by the metabolism, main- tain a free radical balance and prevent aging and disease. Therefore, finding natural resources with strong antioxidant activity has become a new focus for research.

METHODS: Single-factor experiments were used to investigate the effects of various factors (hydrolysis temperature, pH, substrate concentration, enzyme to substrate ratio (E/S), ratio of compound protease (EAlcalase/Epapain) and time on the preparation of antioxidant peptides by compound protease (Alcalase and papain) hydrolysis of goat’s milk casein. Then, a Plackett-Burman design was used to determine the sig- nificant factors for the preparation of antioxidant peptides by hydrolysis of goat’s milk casein with compound protease.

RESULTS: The results of the single-factor experiments indicated that the highest anti-oxidative activity of pep- tides would be obtained at a hydrolysis temperature of 55°C, a pH of 7.5, a substrate concentration of 3.0%, an E/S of 4.0%, a ratio of compound protease of 1/3 and a hydrolysis time of 180 min.

CONCLUSIONS: The main factors affecting the activity of anti-oxidative peptides hydrolyzed from goat’s milk casein with compound protease were determined by Plackett-Burman design and the results showed that temperature, E/S ratio and the ratio of compound protease had significant influences on the production of antioxidant peptides. This could provide a basis and reference for further optimization.