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Please use this identifier to cite or link to this item: http://hdl.handle.net/123456789/3561

Authors: Getachew, Eskindir
Advisors: Dr.Eng. Shimelis Admassu (Asso. Prof.)
Keywords: Hot smoking
Nile tilapia
Shelf stability
Smoked fillet
Copyright: 2011
Date Added: 20-Aug-2012
Abstract: The aim of this study was to investigate the effect of hot smoking on the quality and shelf stability of Nile tilapia (Oreochromis niloticus) fillets. Different combination of temperatures (75/850c), time (8/9 h) and fan speed (570/1120 rpm) were used to prepare eight hot smoked samples having a treatment code of A to H. These samples were evaluated for pH, yield, proximate and mineral composition, microbiological count, sensory analyses and shelf stability. The samples mean proximate composition values ranged from 30.62 - 52.70 % moisture, 84.41- 92.39 % protein, 1.28 - 2.04 % fat, 10.50 - 12.72 % ash contents. Whereas the mean microbial counts (CFU/g) ranged (1.40 - 14.25) X 103 for aerobic plate count (APC), (2.00 - 22.55) X 103 for yeast and mould and at not detectable(ND) range for entrobacteriaceae. Smoking loss mean value also ranged from 57.87 - 63.44 % and at the same time the score of overall average sensory values ranged from 5.99 - 8.12 in 9-point hedonic scale. After six weeks storage of smoked fillet at 40c the log10 microbial counts were 8.78 for APC, 7.36 for yeast and mould, and ND level for entrobacteriaceae. On the other hand after 20th day room temperature storage, the mean log10 microbial counts were 7.05 for APC, 8.39 for yeast and mould, and ND level for entrobacteriaceae. At the end of storage time for both tempratures, APC was slightly grater than the acceptable limit set by ICMSF. Mean TVB-N of smoked fillets has also increased through storage time from 10.25 to 18.06 mg N/100g at 40c storage and 10.25 to 23.69 mg N/100g increment at room temprature storage. These values were lower than the acceptability limit, 35 mg N/100 g of muscle, set by the EC. Based on the findings, modified process technology has been suggested with its techno economic feasibility study. The financial study was viable with return on investment (ROI) of 20.89% and a payback period of 3.33 years. Generally this research has shown that, hot smoking process mainly increases the nutritional value, decreases the microbial load and increases the shelf stability of the tilapia fillets.
URI: http://hdl.handle.net/123456789/3561
Appears in:Thesis - Chemical Engineering

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