Seal Blubber Oil Research Articles

EFFECTS OF PROCESSING AND SQUALENE ON COMPOSITION AND OXIDATIVE STABILITY OF SEAL BLUBBER OIL

Effects of processing on constituents of seal blubber oil and that of squalene on oxidative stability of several oils were monitored. The content of α-tocopherol in oil decreased during processing, especially at the bleaching and deodorization steps. There was also a concurrent reduction in the contents of squalene and free fatty acids, especially during deodorization. Oils treated with squalene did not show any improved oxidative stability and in some cases were even less stable.

Concentration of omega 3-polyunsaturated fatty acids of seal blubber oil by urea complexation: optimization of reaction conditions

Production of omega-3 fatty acid concentrates from seal blubber oil (SBO) was optimized. In this process, the content of total ω3-fatty acids, Y 1; eicosapentaenoic acid (EPA), Y 2; and docosahexaenoic acid (DHA), Y 3 in the final product was maximized. A three-factor central composite rotatable design (CCRD) was used to study the effect of urea-to-fatty acid ratio (X 1), crystallization time (X 2), and crystallization temperature (X 3). Second-order polynomial regression models for Y 1, Y 2 and Y 3 were employed to generate response surfaces. Under optimum conditions the maximum amount of total ω3 fatty acids (88.2%) from SBO was obtained at a urea-to-fatty acid ratio of 4.5, a crystallization time of 24 h, and a crystallization temperature of −10°C. ©

Concentration of ω‐3 polyunsaturated fatty acids of marine oils using Candida cylindracea lipase: Optimization of reaction conditions

AbstractProduction of ω‐3 fatty acid concentrates from seal blubber oil (SBO) and menhaden oil (MHO) upon enzymatic hydrolysis by Candida cylindracea lipase was optimized. In this process, the content of total ω‐3 fatty acids, Y1; eicosapentaenoic acid, Y2; and docosahexaenoic acid, Y3, in the final product was maximized. A three‐factor central composite rotatable design was used to study the effect of enzyme concentration (X1), reaction time (X2), and reaction temperature (X3). Second‐order polynomial regression models for Y1, Y2, and Y3 were employed to generate response surfaces. After hydrolysis, a maximum of 54.3% total ω‐3 fatty acids was obtained from SBO at an enzyme concentration of 308 U/g oil, a reaction time of 40 h, and a reaction temperature of 37°C. Similarly, a maximum of 54.5% total ω‐3 fatty acids was obtained from MHO at an enzyme concentration of 340 U/g oil, a reaction time of 45 h, and a reaction temperature of 38°C.

Antioxidant and pro-oxidant activity of green tea extracts in marine oils

The activity of green tea extracts (GTE) on the oxidation of refined, bleached and deodorized (RBD) seal blubber oil (SBO) and menhaden oil (MHO) was examined under Schaal oven conditions at 65 °C. Progression of oxidation was monitored using weight gain, peroxide value (PV) and 2-thiobarbituric acid-reactive substances (TBARS) data. GTE exhibited a pro-oxidant effect in both oils examined, perhaps due to the catalytic effect of their chlorophyll constituents. Therefore, in follow-up experiments, a column chromatographic technique was employed to remove chlorophyll from GTE. The resultant dechlorophyllized green tea extract (DGTE) was applied to both SBO and MHO at 100, 200, 500 and 1000 ppm levels. The antioxidant activity of DGTE was compared with the effects of the commonly-used antioxidants such as butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT) and tert-butylhydroquinone (TBHQ) at 200 ppm and α-tocopherol at 500 ppm. DGTE at ≥200 ppm exhibited excellent antioxidant activity in both oils and its efficacy was higher than that of BHA, BHT and α-tocopherol, but less than that of TBHQ.

STABILIZATION OF MARINE OILS WITH FLAVONOIDS

ABSTRACTAntioxidant activity of a number of flavonoids in refined‐bleached and deodorized (RBD) seal blubber oil (SBO) and menhaden oil (MHO) was compared with that of commercially used antioxidants, namely butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT) and tert‐butylhydroquinone (TBHQ) as well as α‐tocopherol. The study was carried under Schaal oven conditions at 65C and progression of oxidation was followed by monitoring weight gain, peroxide value (PV) and 2‐thiobarbituric acid reactive substances (TBARS) value. Among the flavonoids tested in this study, the flavonols, namely myricetin, quercetin and morin exhibited a stronger antioxidant activity than BHA and BHT and effectively stabilized both SBO and MHO. Myricetin was the most effective flavonoid tested in this study and its effect in reducing lipid oxidation was similar to that of TBHQ.

Lipase‐assisted concentration of n‐3 polyunsaturated fatty acids in acylglycerols from marine oils

AbstractPreparation of n‐3 polyunsaturated fatty acid (PUFA) concentrates from seal blubber oil (SBO) and menhaden oil (MHO) in the form of acylglycerols was carried out by hydrolysis with a number of commercial microbial lipases. The lipases tested were Aspergillus niger, Candida cylindracea (CC), Chromobacterium viscosum, Geotrichum candidum, Mucor miehei, Pseudomonas sp., Rhizopus oryzae, and Rhizopus niveus. After lipase‐assisted hydrolysis of oils, free fatty acids were removed, and fatty acid composition of the mixture containing mono‐, di‐, and triacylglycerols was determined. All lipases were effective in increasing the n‐3 PUFA content of the remaining acylglycerols of both SBO and MHO. The highest concentration of n‐3 PUFA was provided by CC lipase; 43.5% in SBO [9.75% eicosapentaenoic acid (EPA), 8.61% docosapentaenoic acid (DPA), and 24.0% docosahexaenoic acid (DHA)] and 44.1% in MHO (18.5% EPA, 3.62% DPA, and 17.3% DHA) after 40 h of hydrolysis. Thus, CC lipase appears to be most suitable for preparation of n‐3 PUFA in the acylglycerol form from marine oils.

EFFECT OF PROCESSING ON CONSTITUENTS AND OXIDATIVE STABILITY OF MARINE OILS

ABSTRACTChanges in the contents of neutral and polar lipids, α‐tocopherol, free fatty acids and color of seal blubber oil (SBO) and cod liver oil (CLO) during different processing steps of alkali‐refining, bleaching, and deodorization were monitored. Refined, bleached and deodorized (RBD) SBO and CLO contained approximately 39 and 71% less polar lipids than their crude counterparts, respectively. There was also a reduction of 98.5 and 97.4% in the corresponding free fatty acids content of RBD‐SBO and RBD‐CLO. The content of α‐tocopherol in both oils decreased during processing, especially at the bleaching and deodorization steps. The oxidative stability of SBO and CLO following each processing step was determined by measuring peroxide and 2‐thiobarbituric acid reactive substances values. Results so obtained indicated that crude oils were most stable while their refined‐bleached counterparts were least stable, perhaps due to the removal of endogenous natural antioxidants such as α‐tocopherol during processing of oils.

Enzymatic esterification of θ‐3 fatty acid concentrates from seal blubber oil with glycerol

AbstractEnzymatic synthesis of acyglycerols directly from glycerol and an θ‐3 fatty acid concentrate, prepared from seal blubber oil, in organic solvents was studied. Seven lipases were used as biocatalysts for esterification, Lipase LP‐401‐AS from Chromobacterium viscosum showed the highest activity for esterification. Effects of reaction parameters, namely, temperature, time course, type of solvent, water content, amount of glycerol, enzyme load and solvent volume, were followed with lipase IP‐401‐AS as the biocatalyst of choice. Optimal reaction conditions were established, and the maximal degree of acylglycerol synthesis reached was 94.3%. The concentrations of monoacylglycerols, diacylglycerols, and triacylglycerols were 13.8, 43.1, and 37.4%, respectively. Therefore, acylglycerols containing predominantly θ‐3 fatty acid concentrates may be easily synthesized directly via their reaction with glycerol.

POSITIONAL DISTRIBUTION OF FATTY ACIDS IN TRIACYLGLYCEROLS OF SEAL BLUBBER OIL

ABSTRACTThe positional distribution of long‐chain ω3 polyunsaturated fatty acids namely eicosapentaenoic acid (EPA), docosapentaenoic acid (DPA), and docosahexaenoic acid (DHA) in the triacylglycerol (TAG) molecules of seal blubber oil was determined and compared with that of commercially available menhaden oil via stereospecific analysis. In seal blubber oil, EPA, DPA and DHA occurred mainly in the sn‐1 and sn‐3 positions of the TAG molecules. The amounts were EPA, 8.36 and 11.2; DPA, 3.99 and 8.21; and DHA, 10.5 and 17.9%, respectively. In menhaden oil, DPA and DHA occurred mainly in the sn‐2 position of the TAG at 3.11 and 17.2%, respectively. However, EPA was equally distributed in the sn‐2 and sn‐3 positions and was present only in minute amounts in the sn‐1 position.

SEAL BLUBBER OIL: A NOVEL SOURCE OF ω3 FATTY ACIDS

ABSTRACTMarine oils are perceived as having beneficial health effects since they prevent and treat cardiovascular diseases, among others. The ω3 polyunsaturated fatty acids have been recognized as an essential dietary component. Extensive studies on laboratory animals and human subjects have suggested that ω3 fatty acids may be included in the target tissues and cell membranes by dietary manipulation. The contribution of seal blubber to the total carcass weight is approximately 29% and it contains a high amount of long‐chain ω3 fatty acids. Traditionally seal blubber oil has been used for industrial purposes, however, recent research findings have shown its potential application in foods as well as production of ω3 fatty acid concentrates. This review discusses production of concentrates from seal blubber oil.

Stabilization of seal blubber and menhaden oils with green tea catechins

AbstractCatechins, namely (−)epicatechin (EC), (−)epigallocatechin (EGC), (−)epicatechin gallate (ECG) and (−)epigallocatechin gallate (EGCG), were isolated from commercial Chinese green leaves. The antioxidant activity of isolated catechins was compared with those of α‐tocopherol, butylated hydroxyanisole (BHA), butylated hydroxytolene (BHT) andtert‐butylhydroquinone (TBHQ), all at 200 ppm, in refined, bleached and deodorized seal blubber oil and menhaden oil. The study was carried out under Schaal oven test conditions at 65°C over a 144‐h period, except for weight gain measurements, which were continued for up to 200 h. Progression of oxidation was monitored by measuring changes in weight gain and values of peroxide, conjugated diene, and 2‐thiobarbituric acid‐reactive substances. Oils treated with tea catechins showed excellent oxidative stability as compared with samples that contained commonly used antioxidants, such as α‐tocopherol, BHA, BHT, and TBHQ. The potency of catechins in prevention of oxidation of marine oils was in the decreasing order of ECG> EGCG> EGC> EC; ECG was slightly more effective than TBHQ in systems studied.

Determination of Chlorobiphenyls in Seal Blubber, Marine Sediment, and Fish: Interlaboratory Study

Between 1988 and 1994, the International Council for the Exploration of the Sea, the Intergovernmental Oceanographic Commission, and the Oslo and Paris Commissions organized a stepwise interlaboratory study for determination of chlorobiphenyls (CBs) in marine media. The final parts of this study, in which 53 laboratories from 14 countries participated, focused on long-term precision, cleanup, and extraction. Calibration was controlled continuously by analysis of 10 CBs in an unknown solution. Participants were requested to analyze 3 CBs in a certified reference material fish oil (6 times); 10 CBs in cleaned and uncleaned marine sediment and seal blubber extracts; and 10 CBs in seal blubber oil, dried marine sediment, and wet, lean fish muscle tissue. The long-term precision study showed that, compared with earlier exercises in which only duplicate analyses were required, repeatability increased about 1.5-fold compared with reproducibility. The mean standard error for reproducibility of determination of 10 CBs in standard solutions improved from 1.22 to 1.15. The standard error improved from 1.36 to 1.25 (without CBs 28 and 31) for seal blubber oil and from 1.36 to 1.22 for dried marine sediment. In seal blubber oil and dried marine sediment, the major CBs 118, 138, 153, and 180 can now be determined by the group of participating laboratories with a reproducibility of 1.5 (about 50%). No significant differences were found between results for cleaned-up and uncleaned extracts. No acceptable results could be obtained for determination of CBs in lean fish muscle tissue. Biplots of principal component analyses are extremely helpful in evaluating the data generated by this type of study.

STORAGE STABILITY OF MICROENCAPSULATED SEAL BLUBBER OIL

ABSTRACTThe oxidative stability of microencapsulated seal blubber oil (SBO) was compared with that of its unencapsulated counterpart. Wall materials tested were β‐cyclodextrin, maltodextrin and corn‐syrup solids. Aqueous dispersions containing the wall material, Tween‐80 as an emulsifier, and SBO were thoroughly mixed and then spray‐dried. The storage stability of the spray‐dried products at room temperature was determined by monitoring changes in their fatty acid composition, peroxide, conjugated diene and 2‐thiobarbituric acid reactive substances (TBARS). Among the wall materials tested, β‐cyclodextrin and to a lesser extent corn‐syrup solids were found to be suitable encapsulating agents for SBO, but maltodextrin was inadequate. The encapsulated oils may be easily handled and incorporated into food formulations.

Oxidative stability of oil from blubber of harp seal ( Phoca groenlandica) as assessed by NMR and standard procedures

Oils from seal blubber and cod liver were extracted, refined and bleached in a laboratory scale process. Oxidative stability of oils was evaluated over a 16-day period under accelerated oxidation conditions at 65°C. Peroxide value (PV), contents of conjugated dienes (CD) and trienes (CT), 2-thiobarbituric acid reactive substances (TBARS) and p-anisidine values (AnV) were determined. In addition, NMR spectroscopy was used to monitor relative changes in the proton pattern of the fatty acids of oils during storage. Cod liver oil showed higher PV, CD, CT and TBARS values as compared with seal blubber oil. The ratio of aliphatic to olefinic protons in both oils determined by NMR spectroscopy increased steadily over the entire length of the storage period, indicating progressive oxidation of unsaturated fatty acids in both oils. A significant correlation ( P ≤0·05) was found between these ratios and TOTOX values (2PV + AnV) for both oils, thus suggesting that NMR methodology can be used as an effective means to simultaneously estimate both primary and secondary oxidation changes.

SYSTEMATIC IDENTIFICATION OF FATTY ACIDS IN THE GAS–LIQUID CHROMATOGRAPHY OF FATTY ACID METHYL ESTERS: A PRELIMINARY SURVEY OF SEAL OIL

The fatty acids of a commercial seal blubber oil have been surveyed by application of the linear log plot and separation factor procedures to the gas–liquid chromatograms of methyl esters obtained from urea complexing. These techniques, coupled with the use of two polyesters, have permitted the tentative identification of virtually all of the components. The overall composition of the seal blubber oil appears to cover the same range of fatty acids as the body oils of menhaden and herring.

SYSTEMATIC IDENTIFICATION OF FATTY ACIDS IN THE GAS–LIQUID CHROMATOGRAPHY OF FATTY ACID METHYL ESTERS: A PRELIMINARY SURVEY OF SEAL OIL

The fatty acids of a commercial seal blubber oil have been surveyed by application of the linear log plot and separation factor procedures to the gas–liquid chromatograms of methyl esters obtained from urea complexing. These techniques, coupled with the use of two polyesters, have permitted the tentative identification of virtually all of the components. The overall composition of the seal blubber oil appears to cover the same range of fatty acids as the body oils of menhaden and herring.

The use of low ‐ temperature crystallization in the determination of component acids of liquid fats. IV. Marine animal oils. The component acids and glycerides of a grey (atlantic) seal

AbstractPreliminary crystallization of the mixed fatty acids of marine animal oils from acetone at —60°, followed by ether at —30° or —40°, resolves them into groups, differing widely in unsaturation, which can then be esterified and fractionally distilled. This procedure has great advantages compared with the lithium and lead salt separations which were previously employed. The method has been applied to the component acids, and also to the component glycerides, of the blubber oil of a grey seal (Halichoerus grypus). The composition of the fatty acids of seal blubber oil varies over a somewhat wider range than obtains in the fatty oils of some other marine species. The glycerides belong to the extremely ‘“mixed” type characteristic of marine animal oils. The seal liver contained less than 3% of lipids, which consisted of 29%’ phosphatides, 21% unsaponifiable matter and 50% glycerides 5 the liver glycerides contained a less unsaturated mixture of fatty acids than the blubber glycerides and also a higher content of saturated fatty acids.