Production and purification of antioxidant peptides from a mungbean meal hydrolysate by Virgibacillus sp. SK37 proteinase

• Mungbean meal could be a promising source of antioxidant peptides.
• Virgibacillus sp. SK37 proteinase is a potential processing-aid for antioxidant peptides.
• Antioxidant activity of peptides depends on amino acid composition rather than its mass.
• High antioxidant potency is associated with the presence of C-terminal Arg.
• The purified peptides were stable over a wide pH and temperature range.

Antioxidant peptides of mungbean meal hydrolysed by Virgibacillus sp. SK37 proteinases (VH), Alcalase (AH) and Neutrase (NH) were investigated. The antioxidant activities based on 2,2′-azinobis (3-ethyl-benzothiazoline-6-sulphonate) (ABTS) radical-scavenging, ferric-reducing antioxidant power (FRAP) and metal chelation of VH were comparable to those of NH. VH was purified using ultrafiltration, ion exchange and gel filtration chromatography. The purified peptides (F37) from VH, which had the highest specific antioxidant activity, consisted of four peptides containing an arginine residue at their C-termini. In addition, the ABTS radical-scavenging activity of the purified peptides (F42) at 0.148 mg/ml was comparable to that of 1 mM of butylated hydroxytoluene (BHT). These two fractions were stable over a wide pH (4–10) and temperature (25–121 °C) range. Virgibacillus sp. SK37 proteinase is a potential processing-aid for the production of a mungbean meal hydrolyzate with antioxidant properties.