Optimisation of antioxidant peptide preparation from corn gluten meal

BACKGROUND Corn gluten meal, containing approximately 600gkg(-1) protein, is a main by-product of corn wet milling. The annual output of corn gluten meal in China is over 840000 tons. However, it is difficult to utilise corn gluten meal in the food industry because of its low water solubility and amino acid imbalance. In the present study, corn gluten meal was hydrolysed by different proteases to produce hydrolysates with antioxidant activity in order to increase its value. The hydrolysis conditions were optimised by multiple linear regression and response surface methodology. Furthermore, the amino acid sequence of one corn peptide was determined. RESULTS The optimal conditions for alkaline protease hydrolysis were a pH of 9.5, an enzyme/substrate (E/S) ratio of 8g per 100g, a liquid/solid ratio of 25 mL g(-1) and a time of 75 min, while the optimal conditions for flavourzyme hydrolysis were a pH of 7, an E/S ratio of 4.2g per 100 g and a time of 66 min. After gel filtration chromatography, fraction F2 exhibited the highest antioxidant activities. The amino acid sequence of a purified peptide in fraction F2 was determined as Gly-His-Lys-Pro-Ser (507.2Da). Conclusion The results indicate that corn gluten meal hydrolysates and/or its isolated peptides are potent antioxidants. (c) 2013 Society of Chemical Industry