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Extraction, Biochemical Analysis and Characterization of Oil and Lecithin from Two Selected Fish Species

Sayad Md. Didarul Alam
Department of Biochemistry and Molecular Biology, University of Rajshahi, Rajshahi-6205, Bangladesh

Md. Selim Uddin
Department of Biochemistry and Molecular Biology, University of Rajshahi, Rajshahi-6205, Bangladesh

Sohel Hasan
Department of Biochemistry and Molecular Biology, University of Rajshahi, Rajshahi-6205, Bangladesh

Abstract/ Executive Summary:

Nutrients from Fishes have beneficiary effects on health. To estimate and compare the nutritional status, biochemical compositions of two fish species, Ayre (Sperata aor) and Kani pabda (Ompok bimaculatus), were determined. Kani pabda fish contained higher amount of protein (15.295%) than Ayre fish (13.119%) whereas, lipid content of Ayre was higher (1.90%) than that of Kani pabda (1.31%). All other parameters like moisture, ash and total sugar content were investigated and found to be high in Ayre compared to Kani pabda. The percentage of oil from Ayre and Kani pabda fish powder were 18.22 and 12.59, respectively. The acid value, percentage of FFAs, iodine value and peroxide value of Ayre fish oil were found to be 16.59 (mg KOH/g), 8.342%, 129.337 (mg I/g oil) and 11.55 (meq O2/1000g), respectively, higher than those of Kani pabda fish oil. Similar parameters have also been studied for lecithins extracted from both species having higher oxidative stability due to the presence of natural antioxidants. Consumption of these fish species can prevent malnutrition diseases being a part of proper balanced diet and as a rich source of micronutrients. Furthermore, oil and lecithin isolated from the fish powder provide unsaturated fatty acid molecules that can become useful in food and pharmaceutical industries.

Keywords: PUFA (Poly unsaturated fatty acid); FFA (Free fatty acid); EPA (Eicosapentaenoic acid); DHA (Docosahexaenoic acid)

Location: Department of Biochemistry and Molecular Biology, University of Rajshahi, Rajshahi

Start Date:

End Date:

Program Area: Quality and Nutrition

Commodity: Fish

Objectives:

To assess different nutritional parameters in the selected fish species.

Methodology:

Sample collection and preparation - Due to their availability throughout the country in all seasons, Ayre and Kani pabda fishes were collected from the local market in Rajshahi. After cleaning, bones were removed from fishes, and the flesh was packed in polyethylene bags to store in a refrigerator (at 4^oC) for experimental purposes. Biochemical analysis of fish flesh - Moisture content was determined by the conventional procedure while ash content was determined by the AOAC method. Anthrone method was used to measure the sugar content. Reducing sugar content was quantified by dinitrosalicylic acid method. Non-reducing sugar was also determined in accordance to the method given in AOAC. Anthrone method was used to measure the glycogen content of fish flesh. Total protein and water-soluble protein contents of fishes were determined by the micro-kjeldahl method and Lowry method, respectively. Finally, lipid content of Ayre and Kani pabda fishes were determined by the method of Bligh and Dyer. Extraction of oil from Ayre and Kani pabda fishes - The stored fish samples were sun-dried for about 72 hours and grinded by mechanical grinder. Oil was extracted from both fishes by Soxhlet extraction apparatus using n-hexane and stored at 4⁰C for further analysis. Parameters like specific gravity, iodine value, acid value, percentage of free fatty acid, peroxide value, saponification value and saponification equivalent of fish oil were determined and conventional procedure. Saponification equivalent was calculated from the saponification value. The percentage of free fatty acid was calculated from the acid value. The amount of unsaponifiable matters present in the oil was also determined. Extraction of Lecithin - The stored fish samples obtained by mechanical grinding were used for lecithin extraction. 100 ml of ethanol (95%) was added to 30 g of fish powder residues and stirred for almost 12 hours by a magnetic stirrer. The mixture was then centrifuged at 6000 rpm for 10 min. The supernatant containing mainly polar lipids with very small amounts of neutral lipids was collected using a separator funnel. The precipitate was again extracted with 100 ml of ethanol and after centrifugation and the supernatant was added to that ethanol extract. Twice volume of hexane was mixed with the ethanol extract to separate the neutral lipids from the polar lipids. The ethanol phase was evaporated at 40⁰C. The remaining lipid residue was dissolved in hexane. Volume of this hexane solution was measured and five times the volume of chilled acetone (4⁰C) was added to it (with slow-stirring) to precipitate the gummy material. The mixture was placed in an ice bath for 15 min and then centrifuged at 5000 rpm for 10 min. After discarding supernatant, the collected precipitate (fish lecithin) was stored at −20^o C until further analysis. The iodine value of Ayre and Kani pabda fish lecithin was measured. The saponification value and saponification equivalent of Ayre and Kani pabda fish lecithin were determined according to the method of IUPAC. The acid value of Ayre and Kani pabda fish lecithin was also determined using IUPAC method. AOCS method was used to determine the peroxide value of Ayre and Kani pabda fish lecithin. Measurement of oxidative stability of Ayre and Kani pabda fish lecithin - To measure the oxidative stability, emulsions of lecithin in water were oxidized at 37^oC. Emulsions of lecithin in water (w/w) (linoleic acid 4%, lecithin 1%, water 95%; lecithin 5%, water 95%; β-carotene 1%, lecithin 4%, water 95%) were prepared. Deionized and degassed water were used for emulsion preparation. Linoleic acid and standard β-carotene were used to measure the oxidative stability of fish lecithin. The mixture was properly homogenized using a homogenizer. Oxidative stabilities were checked by the thiocyanate (TC) and thiobarbituric acid (TBA) methods, which were used to measure the antioxidant activity. In this study, these two methods were conducted to measure the quality of the extracted lecithin in terms of its oxidative stability. Statistical analysis - All the experiments were carried out in triplicates and the result was presented as mean ± S.E.

Source of Information: International Journal of Biosciences | IJB ; ISSN: 2220-6655 (Print), 2222-5234 (Online); Vol. 7, No. 6, p. 92-102, 2015

Article Link (Online Journal): http://www.innspub.net; http://dx.doi.org/10.12692/ijb/7.6.92-105

Funding Source:

Budget:

Total Budget (Tk.) :

Achievement/Findings:

In overall, considerable variations were found in the biochemical compositions of Ayre and Kani pabda fish. Protein and lipid content of both fishes were high. The iodine value of Ayre was higher than that of Kani pabda, which indicated that the Ayre fish oil contained more unsaturated fatty acid than Kani pabda fish oil. Higher oxidative stability was found in lecithin from both Ayre and Kani pabda fishes. Therefore, it can be concluded that fish oil and lecithin isolated from these fish species provide unsaturated fatty acids that can be useful in food industries as well as in pharmaceutical industries.

Knowledge Management: Journal