Browsing by Author "Abeyrathna, I.G.S.N.K."

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    Production of Imitation Caviar Using Yellow Fin Tuna Fish Species: Thunnus albacares – A Novel product using Fish Roe in Sri Lanka
    (Uva Wellassa University of Sri Lanka, 2013) Abeyrathna, I.G.S.N.K.; Liyanage, N.P.P.; Thushari, G.G.N.; Jayamanne, C.
    Caviar is defined as salted fish roe that basically prepared with eggs or roe of sturgeon fish. Imitation caviar is defined as roe that comes from a fish other than the sturgeon, and it can be classified as a caviar substitute. This product is not so popular among Sri Lankans, because of lack of knowledge regarding processing of caviar and its cost. In Sri Lanka, fish roe is discarded from processing plants and sold in the local market. Therefore it is important to add value to fish roe and make them a high demanded product. Since discarded fish roe is used for this product, there will be no threat of over exploitation by production of imitation caviar. Local people can acquire nutritional benefits from the imitation caviar due to high nutritional quality. Yellow fin tuna: (Thunnus albacares) was selected as the resource fish species for the present study. T. albacares is a species in family Scombridae found in pelagic water of tropical and subtropical oceans waters. In Sri Lanka, it is considered as a commercially important food fish that represent considerable portion of tuna fishery. Therefore, main objective of present study is to develop proper methodology and select suitable maturity stage of fish roe for production of imitation caviar. Methodology Roe samples of T. albacares were collected from Ceylon Fresh sea food (Pvt) Ltd. and Jay sea food (Pvt) Ltd. in Ja-Ela, Sri Lanka. Then collected samples were transported to the Animal Science laboratory of Uva Wellassa University using cooler boxes with ice. First, ovary sacks with fish roe were separated according to maturity stage as immature roe, half mature roe and mature roe using external features of ovary sac. Then fish roe were separated from the ovary sac using manual screening method. Blood and other connective tissue on the roe were removed by rinsing with 5 % brine solution and fish roe were sieved using the sieve set. Prepared roe samples were subjected to “dry salting method” separately. Surface moisture of the roe samples were removed using clean cloth and arranged in plastic boxes with one layer of powder form Iodized salt and one layer of roe alternatively. Three different salt (g): fish roe (g) ratios as 0.05:1, 0.25:1 and 0.45:1 were used to determine the best ratio/s of each maturity stage after preliminary experimental trials (S:immature roe : S1 -0.05:1, S2-0.25:1 S3-0.45:1/ X:half mature roe: X1-0.05:1, X2- 0.25:1, X3-0.45:1, Y: mature roe: Y1- 0.05:1, Y2- 0.25:1, Y3- 0.45:1). Three replicates were used for each treatment. Salted roe samples were kept for two and half hours. During this period they were pressed gently by fingers for five minutes for effective absorption of salt. Afterwards they were dipped in tap water bath to remove excess salt and then covered with a wet cloth for 4-4.5 hours. Then the caviar were placed in a dry cool place (approximately 20 C) to be dried (Celic et al., 2012). Final products were filled into glass jars manually and pasteurized using hot water bath at 68 C for 45 minutes. Final products were analyzed for different parameters. Protein and fat contents were determined using Kjeldahl method (6.25×N) and Soxhlet method respectively (AOAC, 1990). Moisture content was determined by drying the sample at 105 C to a constant weight (AOAC, 1990). The pH values of the samples were determined with a pH meter and microbial Count (TPC) of the final products was determined. pH and TPC values were recorded once in 07 days for 02 months of storage period (0, 07, 14, 21, 28 days). All final products were evaluated using 30 untrained panelists in terms of color, texture, aroma, salty taste, mouth feel and overall acceptability on a 5 point hedonic scale to identify the organoleptic properties. Differences between mean values of proximate composition, pH values and microbiological factors were analyzed using ANOVA. Friedman non parametric test was used to analyze the results of sensory evaluation. MINITAB statistical package (16 Version) was used for analysis of results at 0.05 probability level. Results and Discussion Based on the results obtained from protein level, lipid content, sensory evaluation and microbial count studies, three samples (Salt: Fish roe by weight) 0.05:1 g, 0.25:1 g and 0.45:1 g of each maturity stage were separately compared to select best sample. Treatment that shows highest protein level, lowest lipid content, greatest consumer preference and lowest microbiological content was selected as the best sample for each maturity stage. S1 (0.05:1; salt: fish roe) was selected for immature stage, whilst X1 (0.05:1; salt: fish roe) and Y2 (0.25:1; salt: fish roe) were selected for half mature stage and mature stage respectively. The ratio of 0.45: 1 (salt: fish roe) was recorded having lowest nutritional quality, unsatisfactory consumer preference and greater microbial count for each maturity stages compared to other two treatments.