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Organoleptic and Bio-chemical Changes of Hilsha (tenualosa Hilsha) Stored in Ice

M.B.A. Talukder
Department of Fisheries Management, Bangladesh Agricultural University, Bangladesh

M.O. Faruque
Department of Aquaculture, Bangladesh Agricultural University, Bangladesh

M.F. Moyaduzzaman
Department of Fisheries Biology and Genetics, Bangladesh Agricultural University, Bangladesh

M.F. Ansaree
Fisheries and Marine Resource Technology Discipline, Khulna University, Bangladesh

M.Z.H. Jewel
Department of Fisheries Biology and Genetics, Bangladesh Agricultural University, Bangladesh

Abstract/ Executive Summary:

The investigation was carried out to evaluate the organoleptic and biochemical changes of Tenualosa hilsha stored in ice to identify the quality deterioration within 14 days. The investigation was carried out in August, 2007. Quality assessment included organoleptic, biochemical (TVB-N, TMA-N and pH) parameters. The organoleptic evaluation and scoring were done from the time of harvest treated as 0 hour and the average score was 10 for Hilsha stored in ambient temperature to compare with the stored condition. This score gradually decreased over the range of time. The concentration of TMA-N, TVB-N and pH were 2.478 ± 0.13 mgN/100g to 17.2825 ± 0.2 mgN/100g; 4.565 ± 0.7 mgN/100g to 13.694 ± 0.7 mgN/100g and 6.3± 0.05 to 8.4±0.2 respectively. Significant statistical level was selected to 0.01 between storage time and values obtained were observed. The result indicated that all the values of TMA-N, TVB-N and pH increased with passing of time whereas in the initial stage of storage the values were low. However, after the storage time of 14 days the T. hilsha lied between the acceptable and unacceptable level. Thus, freshness and acceptability of T. hilsha determined by organoleptic and biochemical assessment (TMA-N, TVB-N and pH) is the reliable and popular method to be used as a practical index of freshness of fish. The present study revealed that immediate icing of T. hilsha ensured a safe and wholesale product which stored in ice immediately.

Keywords: Hilsha (Tenualosa hilsha), Organoleptic, Bio-Chemical change, TMA-N, TVB-N, ambient temperature

Location: Mechua bazar at Ganginarpar Market under the Sadar upazila in Mymensingh district

Start Date: 01-08-2007

End Date: 31-08-2007

Program Area: Postharvest and Agro-processing

Commodity: Hilsa

Objectives:

1. To assess the quality of T. hilsha (assessment of the organoleptic, microbiological and biochemical parameters) during stored at ice and ambient temperature.

Methodology:

Sample collection and preparation - The Tenualosa sample (T. hilsha) was collected with an average weight of 500-600g in iced condition from the Mechua bazar at Ganginarpar Market under the Sadar upazila in Mymensingh district of Bangladesh in August of 2007. The condition of the sample was good considering the freshness at the time of purchase. According to the information of middlemen the samples were caught by fishermen very early in the morning from the river and brought to the market in a bamboo basket. After collecting and storing, the samples were stored in the insulated box with ice at the ratio of Tenualosa: ice=1:2 and were immediately brought to the Quality control laboratory of Faculty of Fisheries of Bangladesh Agricultural University. T. hilsha were stored for a period of 24 hours. Samples were stored in an insulated box and kept in ice at a ratio of ice: Tenualosa (2:1) as mentioned above. Storage environment was maintained by draining the insulated box for melted ice intermittently and more ice was added to keep the temperature at 00C throughout the entire storage period. In order to find out the distinct organoleptic changes with the passage of time in iced condition, at first the test panel was formed with 3 members and then assessed according to the procedure specified by Shewan and Ehrenberg and overall acceptable limit was also scored according to the procedure of Shewan and Eherenbreg as modified by Rase. After evaluating the distinct organoleptic changes within 14 days (on the 1st, 5th, 10th, 11th, 12th and 14th days). Ice was changed every day and drainage of melted ice was ensured. Two samples from the box were withdrawn, in accordance with the distinct organoleptic changes, at intervals of 6 hours to determine the overall quality in terms of bio-chemical parameter i.e. pH, TVB-N and TMA-N. Organoleptic analysis - Organoleptic score sheet was developed for T. hilsha from the score sheet reported by Shewan and Ehenberg for finfish. From the developed organoleptic score sheet, an overall acceptability ranking was done. The organoleptic characteristics emphasized on odour and eye characteristics. While conducting the organoleptic analysis, the room temperature ranged between 25⁰C to 28⁰C. Biochemical analysis - TVB-N (Total volatile base nitrogen) and TMA-N (Tri methyl amine nitrogen) were determined according to the procedure stated in the manual of Siang and Kim. Extract preparation - The extract was prepared by mixing 2g of the minced/ grinded muscle with 8ml of 4% TCA in a 50ml beaker / McCarty bottle and was homogenized well. It left for 30minutes at ambient temperature with occasional grinding. After then, it was filtered through filter paper (Whatman no.1). The filtered solution was kept in McCarty bottle and was labeled. The filtered solution was also stored in a refrigerator at -20°C (to prevent any further chemical, bacterial or enzymatic break down of the muscle). TVB-N Determination - Three Conway’s units were taken which had been thoroughly cleaned with a neutral detergent to remove any contaminant. To the edge of the outer rim of each unit was applied the sealing agent (Vaseline). Using a micropipette, 1ml of inner ring solution was poured into the inner ring of each unit. Into the outer ring of each unit, 1ml of sample extract was poured. 1ml of saturated K2CO3 solution was carefully poured into the outer ring of the each unit, carefully to prevent any entering the inner ring and immediately the units were covered and closed with clip. The solutions in the units were then mixed gently, to prevent any solution mixing from one ring to another. Next, the units were placed in an incubator at 370C for 60 minutes. After that, the unit’s covers were removed and the inner ring solution, now a green color was titrated with 0.02N HCL using a burette (50ml) until green colored solution turned to pink. An average titration volume of HCL was found from the results of three times titration for each fish species muscle sample. For each value the TVB-N values were calculated. A blank test was also carried out using 1ml of 1%TCA, instead of sample extract. TMA-N Determination - Trimethylamine in fish muscle was determined by the Conway technique, which is same as TVB-N determination but prior to addition of potassium carbonate, 1ml of 10% neutralized formalin was pippeted to the extract to react with ammonia and thus allow only the TMA-N to diffuse over the unit. The calculation was done by the same formula as used in the Conway micro-diffusion technique for TVB-N. Measurement of pH - pH measurements were carried out with a pH-meter by placing the electrodes (glass-calomel) into a suspension of fish muscle in distilled water.

Source of Information: BANGLADESH RESEARCH PUBLICATIONS JOURNAL; ISSN: 1998-2003, Volume: 2, Issue: 3, Page: 632-640, May - June, 2009

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Funding Source:

Total Budget (Tk.) :

Achievement/Findings:

Freshness and acceptability of T. hilsha determined by organoleptic and biochemical assessment (TMA-N, TVB-N and pH) is the reliable and popular method to be used as a practical index of freshness of fish. The present study revealed that immediate icing of T. hilsha ensured a safe and wholesale product which stored in ice immediately.

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