Preservative Synergy of Phenol from Tectonia grandis and Some Indigenous Preservatives on Smoked Clarias gariepinus

Abstract

The preservation potentials of phenol produced by hardwood, Tectonia grandis and some selected indigenous preservatives on smoked Clarias gariepinus were investigated in this study. A sample size of 168 catfish was pre-treated with single (10.0% salt (FS), 10.0% lime (FLM), 10.0% pepper (FPP),) and combined (5.0% salt and 5.0% lime (FSL), 5.0% salt and 5.0% pepper (FSP), 5.0% lime and 5.0% pepper (FLP), 3.3% salt, 3.3% lime and 3.3% pepper (FSLP)), untreated serving as control. The fish samples were smoked at 90.0±5.0ºC for 16 hours, stored under ambient conditions for twelve weeks. Phenol (mg/kg) and Total volatile base-Nitrogen (TVB-N, mgN/100g) were determined at 0, 2, 4, 6, 8, 10 and 12 weeks using official methods of analysis of the Association of Official Analytical Chemist. Phenol levels ranged from 1.21±0.01 to 1.31±0.00 mg/kg in untreated samples and 1.16±0.00 (FS) to 1.33 ±0.00 (FLM). Mean values of Total Volatile Bases in Nitrogen (TVB-N) were significantly different (p<0.05), ranging from 14.24±0.02 to 31.38±0.03mgN/100g in untreated samples and 11.06±0.03 (FS) to 128.60±0.04 mgN/100g (FPP) in treated.  The use of pepper as single preservative on smoked fish should be avoided as it must have promoted autolytic process which led to the formation of high level of volatile compounds. This superseded the phenolic effect of T. grandis after 4 weeks of storage during which C. gariepinus could be re-smoked for fresh impartation of the phenol.