Abstract

Spoilage is defined as any alteration in food products that lead to unacceptable attributes to the consumers, mainly perceived through sensory evaluation. After the fish dies, thousands of microscopic organisms that are invisible to the naked eye are present on the layer of its slimy skin and in its intestines. These microorganisms start to multiply and are known as spoilage bacteria. The aim of the study was to identify antibacterial activity of lemon peel extract against bacteria isolated from gills, skin and intestine of fresh Tilapia fish. Thirty (30) samples were collected in clean polythene bags from old market, Wukari Taraba State and the samples were taken to the laboratory for bacteriological analysis. The bacterial loads of the samples were determined using the Pour plate method of inoculation. The colonies obtained were sub-cultured repeatedly to obtain pure cultures. The isolates were identified using gram staining technique and biochemical tests. The organisms isolated were Staphylococcus aureus, Pseudomonas aerunginosa, Bacillus subtilis and Escherichia coli. The total colony counts from the intestine, gills and skin were too numerous to count, 4.40 × 104 and 3.25× 104 respectively. Escherichia coli (41.37%) had the highest occurrence while Bacillus subtilis (17.24%) had the least. lemon peel extract was applied against the isolated bacteria using the disc diffusion method under in vitro conditions. The disc diffusion results indicated that extract of lemon peel significantly inhibited the growth of Staphylococcus aureus, Pseudomonas aerunginosa, Bacillus subtilis and Escherichia coli. Our results suggested that the use of lemon peel extract induced a stronger antibacterial effect.