Quality Assessment of Cold Smoked Hot Smoked and Oven Dried Tilapia nilotica Under Cold Storage Temperature Conditions

摘要

This study was designed to determine the best processing method (cold smoking, hot smoking and oven drying) that will minimize the loss of quality of Tilapia nilotica under cold storage temperature of -25°.Fresh Tilapia nilotica were immediately chilled to keep their fresh quality intact. The chilled samples (of average size 185 gm) were subjected to different processing methods (cold smoking, hot smoking and oven drying) after which they were kept in 3 different sterilized containers and put in a freezer for 3 months at -25°, while samples were taken bi-weekly for chemical analysis. A baseline data of all measured parameters were taken at the beginning (0 day) of the experiment. Also each of the 3 processed samples was subjected to organoleptic assessment, chemical analysis (P.V., F.F.A. T.V.B.-N) and microbial analysis (Isolation, Identification and count). Initial and final proximate analyses were carried out for each of the processed samples. The microbial analysis was carried out on a monthly basis after the initial baseline data was recorded for the fresh fish sample. Proximate composition for both the fresh fish, initial and final fish samples showed no significant variation (p>0.05). Significant variations (p<0.05) were obtained for all measured chemical parameters (P.V., F.F.A. T.V.B.-N microbial count and organoleptic assessment between the three processing methods. The best processing method was hot smoking with zero (0) microbial count, P.V. 3.9 meq kg-1, F.F.A 7.0% and T.V.B.-N 3.02 mg N100 gm 1 fish. Hot smoked products had no microbial count under cold storage conditions of-25° through out the experimental period. This was followed by oven drying, which showed least bacterial count of 2 cf ug-1 up till the 4th week of cold storage. The notable bacterial detected was Staphylococcus aureus (1 cf ug-1) and Bacillus subtilis (1cf ug-1). Lastly the poorest processing method is cold smoking with the highest bacteria count of 150 cf ug-1 where bacterial species were detected in the first 8 weeks of the three months storage period . However, the last 4 weeks of the experiment showed no traces of bacteria for the 3 processing methods. The prominent bacterial species in the cold smoked samples are Staphylococcus aureus (20cf ug-1) and Bacillus subtilis (40 cf ug-1) Psendomonus aureginosa (30 cf ug-1) and Micrococus acidiophilus (35 cf ug-1).