Phytochemical screening of rubberwood "<i>Hevea brasiliensis</i>" and the fuel wood impact on the organoleptic and keeping qualities of smoke- dried Nile tilapia.

Abstract

Qualitative and quantitative phytochemical screening of Rubber wood sample “Hevea brasiliensis” (Sap wood and heart wood) was carried out to determined the bioactive metabolites present in the fuel wood and its effects on the organoleptic and keeping qualities of smoke dried Nile tilapia "Oreochromis niloticus". Ethanol, methanol, chloroform and aqueous extracts were used as solvents for the extraction of the wood parts and standard procedures were employed to determine the phytochemicals present. Preliminary phytochemical screening of H. brasiliensis showed that it consist of Glycosides, Anthracene derivatives, Tannins, Phlobatannins, Flavonoids, Saponins, Alkaloid and Phenols. Quantitative phytochemical screenings of the wood parts were based on the major bioactive constituents (alkaloids, tannins, flavonoids, saponins and phenol) that possess antimicrobial efficacy. There were significant differences (P < 0.05) in the quantitative bioactive phytochemicals between the wood parts (sapwood and heartwood). H. brasiliensis fuel wood sample had calorific value 18469 KJ/Kg and fuel wood performance (FWP) 73.91 % resulting in 77.42 % mean moisture loss in the smoke dried Nile tilapia fish samples stored at ambient temperature (32 ⁰C) and relative humidity (78 %). The mean bacteria and fungi counts were 6.09 x 10⁶ Cfu and 7.79 x 10⁶ Cfu respectively. A total of 15 isolates were obtained and the most predominant bacteria isolates identified were Staphylococcus aureus, Proteus sp. and Bacillus sp., while the fungi were Mucor sp., Penicillum oxalicum and yeast. The use of Rubber wood “H. brassillensis” as fuel wood to smoke dry fish samples is recommended to fish processors due to its enormous phytochemicals attributes (bacteriostatic and bactericidal effects), fuel wood efficiency and organoleptic impact on taste, texture, appearance and acceptability of the smoke dried Nile tilapia fish.

Keywords: phytochemicals, H. brasiliensis, Nile tilapia, smoking, microbial