Antimicrobial Properties of Grape Fruit, Pawpaw and Black Pepper Extracts on Organisms associated with Fish Spoilage

Abstract

On average, Nigeria loses 30-50% of its fish harvest to spoilage. This exacerbates her fish demand-supply gap; hence the need to devise means of mitigating the spoilage. This paper reports the findings of a study that delved into the antimicrobial properties of Grape Fruit (Citrus paradisa), Pawpaw (Carica papaya) and Black Pepper (Piper guineese) extracts on organisms associated with fish spoilage. In the study, the antimicrobial effect of five concentrations (0.1, 0.2., 0.3, 0.4 and 0.5g/ml) of ethanolic, cold and hot water extracts of these plants on spoilage organisms associated with catfish (Clarias gariepinus) were assessed, through measuring inhibition zones, using the cup plate diffusion method. The inhibition zones were found to significantly differ, across extraction method; plant material and extract concentration. Hot water was found to be the best extraction method, with a mean inhibition zone of 4.42 +- 0.38mm; followed by ethanolic and cold water methods, with 3.55 +- 0.47 mm and 0.60 +- 0.15 mm respectively. Among the plant materials, grape peel had the best antimicrobial activity, with a mean inhibition zone of 3.70 + 0.40mm against the eleven microorganisms tested, followed by black pepper (2.68 + 0.42mm) and then pawpaw seed (2.1 + 0.32mm). Key words: Antimicrobialactivity; Piper guineese; Citrus paradisa; Carica papaya