Purification and characterisation of antioxidative peptides from unfractionated rice bran protein hydrolysates

Abayomi P. Adebiyi, Ayobamitale O. Adebiyi, Tomohisa Ogawa, Koji Muramoto

Research output: Contribution to journalArticlepeer-review

59 Citations (Scopus)


Crude rice bran protein (CRBP) was prepared by alkaline extraction and then treated with 0.6 m HCl to remove phytic acid. The phytate-free rice bran protein (PFRBP) was hydrolysed with proteases M, N, S, P and pepsin under optimal conditions. Hydrolysates obtained from various hydrolysis periods were subjected to analysis for their degree of hydrolysis (DH) and functional properties. The hydrolysates were fractionated by reversed-phase column chromatography on Kaseigel ODS resin (120-140 μm) using a stepwise gradient of aqueous ethanol, and their activities were measured. The 40% ethanol fraction of protease P 4 h-hydrolysate was separated by successive reversed-phase high-performance liquid chromatography and the amino acid sequences of isolated antioxidative peptides were determined by a protein sequencer and matrix-assisted laser desorption ionisation-time of flight mass spectrometry. Crude rice bran protein had higher antioxidative activity than PFRBP, due to the presence of phytic acid. Phytate contents of rice bran, CRBP and PFRBP were 2.5%, 1.42% and 0%, respectively. The activity of PFRBP increased upon protease digestion. Protease M hydrolysates showed the highest DH, but the lowest antioxidative activity. Hydrolysates with DH below 10% had higher antioxidative activity than those above 20%. This result indicates that the antioxidative activity of the hydrolysates is inherent to their characteristics amino acid sequences of peptides depending on the protease specificities.

Original languageEnglish
Pages (from-to)35-43
Number of pages9
JournalInternational Journal of Food Science and Technology
Issue number1
Publication statusPublished - 2008 Jan


  • Antioxidative activity
  • Peptides
  • Phytic acid
  • Purification
  • Rice bran protein

ASJC Scopus subject areas

  • Food Science
  • Industrial and Manufacturing Engineering


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