Antioxidant activity of hydrolysates and peptide fractions of glutelin from cocoa (Theobroma cacao L.) seed

Abstract

Glutelin fraction from cocoa almond was hydrolyzed with alcalase for the production of hydrolysates. These were then fractionated by ultrafiltration to obtain peptides with a molecular weight (MW) lower than 3000 Da. The antioxidant activity (AOX) of the hydrolysates and peptides was assessed using 1,1-diphenyl-2-picrylhydrazyl (DPPH•), 2,2´-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS•+), and oxygen radical absorbance capacity (ORAC) assays. Ultrafiltered peptide fraction with the highest AOX was purified by size exclusion chromatography, by which four main peaks were identified with a MW between 535 and 2959 Da. The peptide fraction P1 (MW = 2959 Da) showed the highest capacity to scavenge DPPH• and ABTS•+ radicals with radical scavenging activity DPPH• and ABTS•+ with EC50 values of 237.48 and 19.29 µg/mL, respectively, which were similar to those obtained with glutathione. These results show that enzymatic treatment of cocoa glutelin comprises an attractive bioprocess for the production of peptide fractions with AOX, which could be included in the design of functional foods; moreover, they show an alternative use of cocoa.

Keywords

• Cocoa seed
• glutelin
• ultrafiltration
• bioactive peptides
• electrophoresis
• free radicals
• antioxidant activity