Effect of solution pH and activated carbon dosage on the decolourization ability, nitrogen components and antioxidant activity of peanut meal hydrolysate

Summary Activated carbon was used to remove the colour of peanut meal hydrolysate. Effects of solution pH and activated carbon dosages on the decolourization efficiency, nitrogen components and antioxidant activity of the hydrolysate were investigated. The results showed that the colour and the undigested protein or large peptides could be removed efficiently under acidic condition (pH 2.0–4.0), while less small peptides were adsorbed under this condition. Among these total amino acids (AAs), the loss of aromatic AA (Tyr and Phe) was the largest regardless of the solution pH. Greater loss of acidic AA (Glu and Asp) was observed under acidic condition, while the loss of basic AA (His, Lys and Arg) followed the opposite trend. The antioxidant activity of the hydrolysate was also reduced after decolourization, which was likely due to the loss of total phenolics and peptides containing aromatic and/or acidic AA.