Antimicrobial potency of Xylopia aethiopica Essential oil on Stored Smoked Clarias gariepinus (Burchell, 1822)

Abstract

Smoked fish has a relatively short shelf life. The shelf life of smoked fish can be extended with different preservative methods including use of bio-preservatives. African pepper Essential Oil (ApEO) extracted using hydrodistillation method exhibits antibacterial and antifungal properties. This study assessed the potential of ApEO as an antimicrobial agent in limiting the activities of spoilage microorganisms in smoked catfish during storage at both refrigerated and ambient temperatures. Smoked catfish samples were preserved with synthetic antioxidants and African pepper essential oil (ApEO) as bio-preservative and kept in high density polyethylene bags and aluminum foil pouches. Samples treated with ApEO were sprayed with 1.0% (v/w). The total aerobic bacteria, total coliform and fungal counts of preserved samples were determined using pour plate method. Samples were evaluated at 14 days interval for a period of 84 days for refrigerated (6 ± 2 °C)samples except for the samples stored at ambient temperature (28 ± 2 °C) which was evaluated after 1 week. The initial microbial count of freshly smoked catfish (with or without treatment) was 0.00 log cfu g^-1. At the end of refrigerated storage, the total bacterial, coliform and fungal counts for preserved smoked catfish ranged between 0.00 - 7.88 log cfu g^-1, 0.00 – 6.94 log cfu g^-1 and 0.00 – 7.47 log cfu g^-1, respectively in the two packaging materials used. A combination of 1% (v/w) ApEO with 5% (w/w) salt was effective in limiting bacterial and fungal growth in smoked catfish kept in high density polyethylene bag beyond 10 weeks at refrigerated temperature. The study concluded that the shelf life of smoked catfish was extended by ApEO by limiting the rate of microbial proliferation during storage at refrigerated temperature for 10 weeks.