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Comparative Shelf-life Quality Analysis of Smoked Tilapia Using Two Different Temperatures

Rakhi Das*
Bangladesh Fisheries Research Institute, Mymensingh-2201, Bangladesh

Subhash Chandra Chakraborty
Department of Fisheries Technology, Bangladesh Agricultural University, Mymensingh-2202, Bangladesh

Abu Rayhan
Bangladesh Fisheries Research Institute, Mymensingh-2201, Bangladesh

Abstract/ Executive Summary:

This study evaluated shelf-life quality of two different temperature (60ºC and 80ºC) treated smoked Tilapia (Oreochromis niloticus), by analyzed their biochemical (proximate and chemical) composition and sensory evaluation during storage at refrigeration temperature (4°C). For this purpose a locally made improved smoking kiln was used. Treatment “A” was processed at 60ºC temperature for 2 hrs and “B” was processed at 80ºC temperature for 1.5 hrs under laboratory method. There was a general decline in sensory characteristics i.e. color, texture, odor, general appearance and mean of acceptability of fish- product during storage. The differences in the biochemical composition of the fresh and smoke-dried samples were statistically significant (p<0.05). Moisture (%) and TVB-N value (mgN/100gm) increased significantly whereas protein (%), lipid (%) and ash (%) content significantly decreased. The initial value of moisture, protein, lipid, ash, salt and TVB-N of freshly smoked Tilapia was 67.55%, 18.77%, 4.26%, 3.52%, 9.37%, 4.29% in treatment A and 72.05%, 17.64%, 4.24%, 4.36%, 5.31%, 5.24% in treatment B respectively. Between these two different temperatures treated Smoked Tilapia, product prepared at 60°C treatment A became spoiled at 65 days whereas product prepared at 80°C treatment B smoke-dried product remain in good condition up to 45 days. This is because of the variation of temperature affects the moisture content of product. Due to high temperature (80 ºC) moisture content remain high and product’s shelf-life decrease and product comparatively soft. Whereas at 60ºC temperature product comparatively hard and had longer shelf-life. Therefore, considering all the quality parameters it showed that the hot smoked products prepared at 60ºC could be stored for two months after smoking retaining its unique taste and flavor.

Keywords: Tilapia, Smoking, Shelf-life, Smoking kiln, Organoleptic evaluation

Location: Bangladesh Fisheries Research Institute, Mymensingh-2201, Bangladesh

Start Date:

End Date:

Program Area: Quality and Nutrition

Commodity: Tilapia

Objectives:

This would probably be a good quality smoked-cured fish product to be introduced publicly in the country. With the advanced of new technologies, people are interested in convenience food with good quality. This is the time to introduce this less known and ready to eat fishery product to popularize in the country which would show a considerable length of shelf-life with good taste, and meet the growing demand among all ages including young generation.

Methodology:

Smoking process For the study, fresh mature (average wt. 350±5gm).Tilapia (Oreochromis niloticus) was collected from the market of “Kamal Ranajit Market”, BAU Mymensing. A total number of sixteen fish was selected randomly for the purpose and carried to the laboratory of Fisheries Technology, Bangladesh Agricultural University, Mymensingh, Bangladesh. The fish were gutted and washed thoroughly with clean water. The fishes were then beheaded with a sharp knife and filleted from neck towards the tail.Then fillets prepared for two experiments soaked into 26% brine solution for 30 minutes. The samples were then kept on racks and put in the smoking kiln. Total smoking time used in this experiment was about 2.0 hours for 60^oC and 1.5 hrs for 80^oC. The maximum temperature in the smoking chamber was 100°C.The smoke temperature was recorded every 10 minutes so that the temperature inside the kiln becomes homogenous. The smoke produced by the burning of sawdust was made of black berry (Syzygium cumini) tree and collected from a local saw-mill. After smoking, the products were packed in transparent polyethylene bags, sealed with a electrical sealing machine (PFS-300) to reduce microbial infestation and stored at room temperature for further studies.

Smoking kiln The fishes were smoked in improved traditional type of smoking kiln (Sarkar, 2005). The smoking kiln or smoking chamber was made with steel as a rectangular box of 105×75×45 cm³ size. Horizontally, the box or chamber was divided into two equal parts by using a horizontal perforated iron net-frame and the bottom portion was used as base for burning saw dust as smoke source. The upper chamber had facilities of hanging 4-6 mm iron rods supported from two sides as rack. Both the chamber had door which could be opened when needed. On the top, there was an outlet for smoke control. By controlling the lid of the outlet the smoke temperature inside the fish chamber i.e. the upper chamber could be controlled. Another small hole on the top was used to provide a thermometer to measure the temperature inside the chamber. Smoking was achieved by burning of wood sawdust. The moderately hot smoke (temperature 75- 80^oC) arose through the big hole into the upper chamber where fish fillets were hung separately.

Estimation of sensory score value The quality assessment as well as sensory evaluation (score) was carried out every three months intervals for samples stored at refrigeration temperature (4°C) using trained panel of four judges until it was an acceptable condition (Debnath, 2009). The questionnaires were prepared using 9- point hedonic score described by Larmond to evaluate changes in color, flavor, texture and mean of general acceptability until it was an acceptable condition. Parameters on the questionnaires were as follows: Like extremely = 9; Like very much = 8; Like moderately = 7; Like slightly = 6; Neither like nor dislike = 5; Dislike slightly = 4; Dislike moderately = 3; Dislike very much = 2; and Dislike extremely = 1 (Larmond, 1977).

Estimation of biochemical composition Using conventional method of AOAC (Association of Official Analytical Chemicals), the proximate composition of fish was determined (AOAC, 1990). Estimation of moisture About 5 gram of previously prepared fairly minced samples were taken into each known weight basin and weighed in a digital balance (Toledo, Switzerland). The samples were allowed to dry into the oven (Memmet 854 Schwabach) at 105°C for 24 hours in order to remove the moisture until constant weight. After that, the basins are taken out of the oven, cooled in a desiccators and were weighed in a digital balance.

% of moisture content = E/C x 100

Where, E= Weight of moisture C=Weight of sample

Source of Information: International Journal of Applied Research 3(2) 35-41

Article Link (Online Journal):

Funding Source:

Budget:

Total Budget (Tk.) :

Achievement/Findings:

The results of biochemical analysis and sensory evaluation carried out proves that the overall shelflife quality of Smoked Tilapia prepared at two different temperature 60ºC and at 80ºC had longer shelf-life of 65 days and 45 days in treatments A and B respectively showing the best ‘A’ which had 65 days of shelf-life with all its sensory qualities as good condition. The variation of temperature affects the moisture content of product. Due to high temperature (80ºC) moisture content remain high and product’s shelf-life decrease and product comparatively soft. Whereas at 60ºC temperature product comparatively hard and had longer shelflife. From this research, it can be concluded that smoke-dried Tilapia products can provide satisfactory nutrition to the nation.

Knowledge Management: Journal