Antioxidant and antibacterial properties of Monodora myristica (Calabash nutmeg) seed protein hydrolysates

Abstract

The purpose of this study was to investigate some of the properties (antioxidant, antibacterial and functional properties) of Monodora myristica seed protein hydrolysates. Monodora myristica protein was extracted using alkaline solubilization, followed by acid precipitation to its isoelectric point. Monodora myristica seed protein isolate was hydrolyzed using three enzymes separately (pepsin, trypsin and pancreatin). Antioxidant activities (2,2-diphenyl-1-picrylhydrazyl (DPPH)-radical scavenging and ferrous ion (Fe2+)-chelating) were determined using standard procedures. Antibacterial activities of protein hydrolysates were done using zone of inhibition test. All protein hydrolysates of Monodora myristica had significantly high DPPH radical scavenging and Fe2+-chelating properties and were soluble over a wide pH range with more than 30% solubility. Pepsin hydrolysate had the highest foam expansion and stability of 117.4% and 98%, respectively and trypsin hydrolysate showed the lowest foam expansion and stability of 97.8% and 78.2%, respectively. Only proteins hydrolyzed with pepsin (regardless of the duration of hydrolysis) demonstrated potent antibacterial activity on test bacteria (Escherichia coli, Staphylococcus aureus, Staphylococcus epidermidis and Proteus vulgaris). It could be deduced from this study that enzymatic hydrolysates of Monodora myristica protein has potential application among functional foods, and may be a promising source of natural antioxidants and antibacterial drugs.