Antioxidant and antibacterial activities of indigenous plant leaf ethanolic extracts and their use for extending the shelf‐life of Nile tilapia (Oreochromis niloticus) mince

Abstract

SummaryLong pepper (LP), soursop (SS), green vein kratom (GK), and red vein kratom (RK) leaf ethanolic extracts were prepared using an ultrasonic device, followed by dechlorophyllization by the sedimentation process. Antioxidant and antimicrobial activities of the extracts were studied. Highest yield and total phenolic content were found in RK extract (P < 0.05). In general, RK extract showed the lowest minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) towards four bacteria (Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa, and Shewanella sp.), when compared with other extracts. Addition of GK extract at 600 mg kg−1 retarded chemical changes and lowered microbiological growth in Nile tilapia mince within 12 days at 4 °C. Lipid oxidation was also impeded with the aid of GK extract. Therefore, GK extract inhibited both spoilage and pathogenic bacteria, and prevented lipid oxidation, thus extending the shelf‐life of tilapia mince.