Safety Profile Assessment and Identification of Volatile Compounds of Krill Eupausia superba Oil and Residues Using Different Extraction Methods
Safety Profile Assessment and Identification of Volatile Compounds of Krill Eupausia superba Oil and Residues Using Different Extraction Methods
Fisheries and aquatic sciences. 2014. Jun, 17(2): 159-165
2014 © The Korean Society of Fisheries and Aquatic Science
This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial Licens ( permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.
  • Received : May 28, 2013
  • Accepted : December 30, 2013
  • Published : June 30, 2014
Export by style
Cited by
About the Authors
A.S.M. Tanbirul, Haque
Department of Food Science and Technology, Pukyong National University, Busan 608-737Korea.
Seon-Bong, Kim
Department of Food Science and Technology, Pukyong National University, Busan 608-737Korea.
Yang-Bong, Lee
Department of Food Science and Technology, Pukyong National University, Busan 608-737Korea.
Byung-Soo, Chun
Department of Food Science and Technology, Pukyong National University, Busan 608-737Korea.

In this study, Krill Eupausia superba oil was extracted using different solvents and supercritical carbon dioxide (SC-CO 2 ). During SC-CO 2 extraction, the pressure was set at 40 MPa and temperatures ranged from 40°C to 55°C. We examined the differences in volatile compounds and safety profiles among extraction methods. Volatile compounds were determined using the thermal desorption system integrated with gas chromatography-mass spectrometry (GC-MS). Heavy metal content was analyzed by inductively coupled plasma mass spectrometry (ICP-MS). According to our results 10 volatile compounds were identified in krill sample. After SC-CO 2 extraction of oil, the concentrations of volatile compounds decreased, but increased after solvent extraction. In krill, heavy metal concentrations remained within the permissible limit. Moreover, Zn and Fe which have health benefits were detected at high concentrations. During a 90 days storage period at different temperatures, microbial activity was found to be lowest in SC-CO 2 extracted residues. Thus, the quality of krill oil and the residues obtained using SC-CO 2 extraction was higher and the oil was safer than those obtained using conventional solvent extraction. These results can be applied to the food industry to maintain high quality krill products.
Marine products have substantial nutritional worth and functional properties, due to the protein fish provide 17% of the total animal protein and 6% of all protein consumed by human (Jose et al., 2007 ). In addition, they serve as high-quality source of vitamin and minerals, and contain high levels of polyunsaturated fatty acids (PUFAs).
Krill are small crustaceans of the order Euphausiacea, and found in all oceans. Similar to other marine animals, Antarctic krill Euphausia superba is a rich source of PUFAs, mainly the long-chain omega-3 fatty acids that have important health benefits: eicosapentaenoic acid (EPA, C 20:5n3) and docosahexaenoic acid (DHA, C 22:5). Particular attention has been paid to eicosapentaenoic acid (EPA, 20:5n3), which decreased blood viscosity and the platelets aggregation, promotes vaso-dilation (Harris, 1997 ). DHA, which promotes the sensorial and neuronal maturation in infants, is often included as a supplement in the diets of pregnant women (O’Connor et al., 2001 ;Di benedetto et al., 2007 ;Kraus-etschmann et al., 2007 ).
Despite the presence of variable functional compounds in the krill oil, however, it contains many different sorts of flavors which effect on quality of product and several studies have reported on fish sauce flavors (Peralta et al., 1996 ). The volatiles found in seafood consist mainly of a variety of unsaturated carbonyls and alcohols, as well as hydrocarbons, acids and esters, derived from enzymatic and non-enzymatic oxidation of PUFAs (Josephson et al., 1984 ;Josephson, 1991 ). Aromatics, phenolic compounds, sulfur-containing compounds, terpenes, pyrazines, pyridines, furans and miscellaneous compounds have also been reported in seafood (Chung et al., 2002 ;Grigorakis et al., 2003 ;Alasalvar et al., 2005 ) and various mechanisms for their production have been proposed (Piveteau et al., 2000 ;Methven et al., 2007 ).
Heavy metals are potentially harmful elements for most aquatic and terrestrial organisms at some concentration of uptake. Environmental factors such as pH, salinity, dissolved oxygen (DO) and temperature (Eastwood and Couture, 2002 ;Dural et al., 2007 ) as well as ecological factors such as sex, size and feed habit plays major roles in heavy metal accumulation in aquatic organisms (Turkmen et al., 2005 ). Fish and other marine invertebrates are considered as an appropriate bio-indicators for metals concentration in aquatic ecosystems (Domingo et al., 2007 ), because it could concentrate large amount of some metals in their tissues (Yılmaz et al., 2007 ). Heavy metal accumulation in fish may increase metals intake by human consumers, causing negative health consequences.
Microorganisms are another major concern for food safety. Both extrinsic and intrinsic parameters affect the growth of microorganisms in food products. Extrinsic parameters include environmental properties (processing and storage) external to the food product, which affect both the foods and their microorganisms. Intrinsic parameters are properties of the food product itself. For example, animal tissues can promote the growth of microorganisms under specific conditions. Refrigeration preserves food by slowing down the growth and reproduction of microorganisms and the actions of enzymes that cause food to rot. Freezing is also commonly used to preserve a wide range of foods, including those already prepared that do not require freezing in their unprepared state.
Supercritical carbon dioxide (SC-CO 2 ) is a nonflammable, non-toxic and inert supercritical solvent, low critical temperature; it can thus be used in the food and pharmaceutical industries. In recent years, the use of supercritical fluid extraction (SFE) to remove organic compounds from various liquid and solid matrices has been explored. This technique has some advantages over more conventional separation techniques, largely due to the unique physical properties of SFs. SFE using CO 2 is promising approach for the extraction and fractionation of edible oils containing labile PUFAs and lipid soluble bioactive compounds.
The objectives of this study were to extract oil from krill using SC-CO 2, to provide an initial screening of volatile organic compounds in oil and residues and to compare with solvent extracted krill oil and residues. As for safety profile checking heavy metal content and microbial activity were assessed.
Materials and Methods
- Materials
Antarctic krill were collected from Dongwon F&B Co. Ltd. (Seol, South Korea). Krill blocks were stored at -30°C for less than 1 year until use. CO 2 (99.99% pure) was supplied by KOSEM Co. (Gumi, Korea). All other reagents used in various analyses were analytical of HPLC grade.
- Sample preparation
Krill samples were dried in a freeze-drier (EYELA FDV-2100; Rikakikai Co. Ltd., Tokyo, Japan) for 72 h. Dried samples were crushed and sieved through a sieve (700 µm mesh size). Then crushed samples were stored at -30°C until using for SC-CO 2 and organic solvent extraction.
- Supercritical carbon dioxide (SC-CO2) extraction
A laboratory setup pilot scale supercritical fluid extraction unit was used to extract oil from krill. This apparatus was used for extracting a large amount of oil and can be operated at pressure up to 70 MPa. Freeze-dried krill samples (600 g) were loaded into stainless steel extraction vessel, which was closed tightly with a stainless steel cap. After that extraction vessel was put into the extractor unit. CO 2 was pumped at constant pressure into the extractor unit with a high pressure pump up to the desired pressure. A back pressure regulator was used to control the CO 2 pressure. The extraction temperature was maintained by connecting the extractor unit to a water bath (MAT’L: SUS 304, Ilshin Autoclave Co. Ltd., Daejeon, Korea). Krill oil was extracted using SC-CO 2 at different temperatures and a pressure of 40 MPa. The conditions remained constant during the 2.5 h extraction period. The extracted oil and residues were collected and stored at -30°C until further analysis.
- Solvent extraction
Ethanol and hexane were used as solvents for solvent extraction. Freeze dried and crashed samples (200g) were placed in beakers and stirred for 24 h at 40°C at 250 rpm. After extraction, the solvent was evaporated in a rotary vacuum evaporator at 40°C. The extracted oil was collected in a vial and stored at -30°C until further analysis.
- Identifying of volatile compounds of krill
Krill oil was prepared using the high volume headspace vial method. Briefly, 5 mL aliquot of sample was placed in a 250 mL dark vial (Supelco Inc., Bellefonte, PA, USA). The vial was capped with a PTEE septum (QMX Laboratories Ltd., Essex, UK) and placed in an oven (50°C for 10 min) to release volatile compounds. The sample was equilibrated for 1 h at the required temperature and the headspace gases were absorbed onto a triple-bed adsorption tube using a vacuum pump and mass flow controller (AALBORG Instrument and Controls Inc., Orangeburg, NY, USA). The triple-bed adsorbent tube consisted of a three-bed packed Tenax-TA (Supleco Inc.) with a small amount of Carbopack B (Supleco Inc.) and Carbosieve SII (Supleco Inc.) (Seo and Lee, 2010 ). The percentage of identified off-flavor was presented by peak area (Area%).
- Measurement of heavy metal contents in krill
Samples were prepared as described by Khalifa et al. (Seo and Lee, 2010 ) with minor modifications. 1 g of each sample was dissolved in 1 M of nitric acid (10 mL), boiled at 130°C to complete the dissolution and filtered. The obtained precipitate was washed with nitric acid (1 M), transferred to a 25 mL volumetric flask and fill with de-ionized water up to the level. The heavy metals content were analyzed using PerkinElmer Elan 6100 ICP-MS (PerkinElmer, Waltham, MA, USA).
- Analysis of the microbial safety of krill residues
Colony counts were performed using spread plate method (Gilbert et al., 2000 ;Cappuccino and Sherman, 2002 ). The sample were diluted at 10 -1 , 10 -2 , 10 -3 , 10 -4 folds in 0.9% saline water. Nutrient agar (Merck KGaA, Darmstadt, Germany) was used as growth medium for bacterial strains and sterilized at 121°C for 15 min. The agar was poured into sterile glass Petri dishes and allowed for a moment until stiff agar forming. Nutrient agar plates were inoculated with 1 mL of diluted krill powder samples and incubated at 37°C. After 24 h of incubation, the total number of colonies was counted. Enumerated bacteria are expressed in CFU/mL (CFU= colony forming units).
- Acid value
The acid value (AV) was assessed according to the method described previously by Ping et al. (Cappuccino and Sherman, 2008 ). 1 g of sample was dissolved in 100 mL of ether:ethanol (1:1, v/v) by shaking, after which phenolphthalein, as an indicator was added by drops. AV of oil was analyzed by titration with a 0.1 N KOH–ethanol solutions until the pink color persisted for at least 30 s, and it was calculated using the following equation:
\[ {\mathrm{Acid}}\hspace{0.33em}{\mathrm{value}}\hspace{0.33em}{\mathrm{(}}{\mathrm{AV}}{\mathrm{)}}\mathrm{{=}}{\mathrm{56}}{\mathrm{.}}{\mathrm{11}}\hspace{0.33em}{×}\hspace{0.33em}{A}\hspace{0.33em}{×}\hspace{0.33em}{F}{\mathrm{/}}{S} \]
where, A is volume of the KOH-ethanol solution of the titration (mL), F is concentration of the KOH-ethanol factor, S is mass of oil (g), and 56.11 is molecular weight of KOH in mg.
- Peroxide value
The peroxide value (POV) was determined according to the American Oil Chemists’s Society (AOCS) method Cd 8-53 (AOCS, 1998 ) using modified amount of sample. One gram of krill oil was dissolved in 6 mL of a 3:2 acetic acid:chloroform solution. Then, 0.1 mL of saturated potassium iodine (KI) solution was added to the mixture and allowed to stand with occasional shaking for 1 min. Distilled water (6 mL) was immediately added to the solution allowed to stand. The solution was titrated with 0.1 N of sodium thiosulfate until the yellow iodine color almost disappeared. Next, 0.4 mL of a starch indicator solution was added by shaking to extract iodine from chloroform layer, and again titrated until the blue color disappeared. A blank determination was performed with the same procedure. POVs were expressed as milliequivalents of a peroxide/1,000 g sample:
\[ {\mathrm{Peroxide}}\hspace{0.33em}{\mathrm{value}}\hspace{0.33em}{\mathrm{(}}{\mathrm{P}}{\mathrm{O}}{\mathrm{V}}{\mathrm{)}}\hspace{0.33em}\mathrm{{=}}\hspace{0.33em}\frac{\hspace{0.33em}\hspace{0.33em}\hspace{0.33em}\hspace{0.33em}{\mathrm{(}}{A}\mathrm{{-}}{B}{\mathrm{)}}\mathrm{\times}{N}\mathrm{\times}{\mathrm{1000}}\hspace{0.33em}\hspace{0.33em}\hspace{0.33em}\hspace{0.33em}}{W} \]
where, A is volume of titrant of sample (mL), B is volume of titrant of blank (mL), N is normality of sodium thiosulfate solution, W is mass of sample (g).
Results and Discussion
- Identification of off-flavor compounds in krill oil and residues
The volatile off-flavor profile was obtained for krill in the sample before and after solvent and SC-CO 2 extraction (Table 1 ). Ten volatile compounds in total were identified. Detected compounds were classified as various chemicals, including alkenes, alcohols, aldehydes and other compounds. Methyl ethyl ketone and toluene were prominent in the freeze dried sample (before extraction) but solvent extraction decreased the concentrations of both in residues and oil. However, rest of the identified off flavor compounds were increased in both residues and oil.
After SC-CO 2 extraction, the concentration of volatile compounds decreased in oil at different temperature (40°C and 55°C) in agreement with previous reports by Roh et al. (AOCS, 2006 ) and Lee et al. (AOCS, 2008 ). In residues the concentration of volatile compounds typically decreased, but in some cases, the concentration of volatile compounds was higher in residues than in the original sample. However, the off-flavor was more effectively removed from oil using SC-CO 2 extraction compared to solvent extraction.
Volatile compounds and their amounta(Area%) identified in krill oil and residues after using different extraction methods
Compounds name Freeze dried krill Ethanol Extracted Hexane Extracted SC-CO 2Extracted (40MPa)
40°C 55°C
Residues Oil Residues Oil Residues Oil Residues Oil
Mercaptomethane 8.33 ± 0.08 2.72 ± 0.03 0.29 ± 0.02 1.07 ± 0.04 2.15 ± 0.05 2.5 ± 0.02 0.48 ± 0.06 4.01 ± 0.02 ND
Methyl ethyl ketone 26.97 ± 0.06 45.81 ± 0.05 37.81 ± 0.03 55.07 ± 0.03 ND 49.16 ± 0.04 17.75 ± 0.04 40.53 ± 0.05 16.94 ± 0.05
i-Valeraldehyde 2.19 ± 0.04 2.16 ± 0.05 11.35 ± 0.07 2.47 ± 0.05 17.57 ± 0.07 1.98 ± 0.05 0.85 ± 0.02 8.046 ± 0.03 74.19 ± 0.03
n-Valeraldehyde ND ND ND ND ND 0.26 ± 0.03 0.4 ± 0.02 ND ND
Disulfide, dimethyl 6.27 ± 0.06 16.65 ± 0.04 42.78 ± 0.06 25.37 ± 0.07 14.71 ± 0.03 13.41 ± 0.05 ND 29.79 ± 0.06 3.19 ± 0.04
Toluene 46.26 ± 0.03 30.58 ± 0.05 3.37 ± 0.03 12.65 ± 0.04 38.74 ± 0.06 30.41 ± 0.07 72.57 ± 0.05 14.52 ± 0.03 2.59 ± 0.07
Isovaleric acid ND ND 0.007 ± 0.02 ND 0.02 ± 0.03 ND ND ND 0.3 ± 0.08
m,p-Xylene 3.21 ± 0.02 ND ND ND 16.1 ± 0.02 ND ND 1.36 ± 0.05 0.77 ± 0.03
Styrene 1.71 ± 0.05 1.71 ± 0.02 4.36 ± 0.04 2.81 ± 0.06 1.28 ± 0.04 1.5 ± 0.03 3.21 ± 0.07 0.58 ± 0.02 0.24 ± 0.05
o-Xylene 5.03 ± 0.04 5.03 ± 0.05 ND 0.53 ± 0.04 9.42 ± 0.02 0.75 ± 0.06 4.7 ± 0.03 0.59 ± 0.04 0.93 ± 0.03
mean ± standard deviation ( n=3) ND, not detected SC-CO 2, supercritical CO 2
- Measurement of Heavy metal contents in krill powder
Heavy metal values of freeze-dried krill are shown in Table 2 . Using different extraction methods, heavy metal concentrations in residues showed some variation. The lead (Pb) concentration before extraction was 0.345 mg/kg but after extraction, the Pb concentration increased in all extraction method and slightly exceeded the maximum level (0.4 to 0.5 mg/kg) specified by Commission of the European Communities (AOCS, 2002 ) and Australia New Zealand Food Authority (AOCS, 2002 ).
The mercury (Hg) concentration was 0.509 mg/kgbefore extraction but after solvent extraction Hg concentration was increased. In SC-CO 2 extracted residue, the Hg concentration decreased (0.248 mg/kg) to concentrations bellow the restricted international standards (0.3 to 0.5 mg/kg) specified by Hong Kong government (FEHD, 1983 ).
The concentration of zink (Zn) also increased after extraction. The highest concentration was found in hexane extracted residues (68.99 mg/kg) and was below the maximum permissible limit (667 mg/kg) according to the Ministry of public health, Thailand (MPHT, 1986 ).
The concentration of cadmium (Cd) was highest (0.630 mg/kg) in hexane extracted residues and did not exceed the maximum permissible limit (1.8 mg/kg) (ICES, 1988 ).
In freeze dried sample the concentration of arsenic (As) was 8.96 mg/kg and lowest (5.166 mg/kg) in ethanol extracted residues. The concentration of Arsenic (As) in krill was below the permissible limit of 76 mg/kg established by the USFDA (ICES, 1993 ).
The concentration of iron (Fe) also increased after extraction and the highest concentration was observed in hexane extracted residues. Thus, heavy metal concentration in krill was below the highest permissible limit. These levels are therefore not hazardous to human health. On the other hand, Fe and Zn were found highest amount, which are beneficial for human health. So it can be good source of Fe and Zn.
Heavy metals contents (mean ± SD,n= 3) analysis in different extracted krill residues
Heavy Metal Freeze dried krill (mg/kg) Ethanol extracted (mg/kg) Hexane extracted (mg/kg) SC-CO 2 * extracted (mg/kg)
Lead (Pb) 0.35 ± 0.02 0.53 ± 0.05 0.51 ± 0.02 0.68 ± 0.04
Cadmium (Cd) 0.56 ± 0.06 0.61 ± 0.05 0.63 ± 0.04 0.60 ± 0.05
Arsenic (As) 8.96 ± 0.02 5.17 ± 0.03 7.90 ± 0.03 7.82 ± 0.02
Zink (Zn) 57.73 ± 0.07 65.20 ± 0.06 68.99 ± 0.04 67.97 ± 0.07
Iron (Fe) 82.40 ± 0.03 99.90 ± 0.03 119.00 ± 0.07 95.40 ± 0.08
Mercury (Hg) 0.51 ± 0.05 0.74 ± 0.02 0.74 ± 0.08 0.25 ± 0.04
Supercritical CO 2.
- Measurement of microbial safety
Microbial safety is an important indicator to determine the quality of protein and storage period. Thus, freeze dried sample and extracted residues from different system were compared in certain days (90 days) interval at different temperature (5°C, -30°C, 20°C). Changes in total bacterial levels in oil extracted residues at different storage times are shown in Figs. 1 , 2 , 3 . The total number of bacteria was increased in residues with storage period. It was found that SC-CO 2 extracted powder showed lowest microbial growth at different temperatures during storage. High pressure CO 2 , various types of microbial activity can reduce the thing have been reported, and this inactivation mechanism of carbon dioxide, the fluidity and permeability with an increase in their essential areas destroyed as easily through the membrane can penetrate (Isenschimid et al., 1995 ). Additionally, under pressure, excessive CO 2 passes through cell membranes and pH buffering capacity of cell gradients and proton motive forces fail due to lower internal pH (Hong and Pyun, 1999 ). However, SC-CO 2 extraction method can be good method than solvent extraction method to maintain the krill product for long time storage.
PPT Slide
Lager Image
The changes of total counts (log CFU/ mL) at 5 oCduring storage period. Error bars represent standard deviation with three replicates.
PPT Slide
Lager Image
The changes of total counts (log CFU/ mL) at 20 oCduring storage period. Error bars represent standard deviation with three replicates.
PPT Slide
Lager Image
The change of total counts (log CFU/ mL) at -30 oCduring storage period. Error bars represent standard deviation with three replicates.
- Comparison of Acid value (AV) and Peroxide value (POV) of krill oil
AV and POV were determined to measure the oil quality and the oxidation state of lipids. It is used to measure the rancidity which occurs by auto oxidation state of lipid. POV increases when the oil is oxidized and AV increases when it is hydrolyzed. It was found that with increasing temperatures, both the AV and POV increased (Figs. 4 and 5 ). That result proportionally associated with free fatty acid (FFA) contents (Kanai et al., 2010 ). In supercritical CO 2 extraction, all the values were found lowest at 40°C.
PPT Slide
Lager Image
Comparison the acid value of krill oil after using different extraction methods. Error bars represent standard deviation with three replicates.
PPT Slide
Lager Image
Comparison the peroxide value of krill oil after using different extraction methods. Error bars represent standard deviation with three replicates.
This research was supported by Technology Development Program for Fisheries, Ministry for Food, Agriculture, Forestry and Fisheries, Republic of Korea.
Alasalvar C , Al-Farsi M , Shahidi F 2005 Compositional characteristics and antioxidant components of cherry laurel varieties and pekmez Food Sci 70 S47 - S52    DOI : 10.1111/j.1365-2621.2005.tb09064.x
American Oil Chemists’ Society (AOCS) 1998 Official Methods of Analysis 5th ed AOCS Champaign, IL, US
Australia New Zealand Food Authority 2002 Standards Code Part 1.4-Contaminants and Residues [Internet] Food Standards Australia New Zealand (FSANZ)
Cappuccino JG , Sherman N 2002 Microbiology: A Laboratory Manual 6th ed Dorling Kindersley Pvt. Ltd Noida, IN 493 - 494
Chung HY , Yung IKS , Ma WCJ , Kim JS 2002 Analysis of volatile components in frozen and dried scallops (patinopecten yessoensis) by gas chromatography/mass spectrometry Food Res Int 35 43 - 53    DOI : 10.1016/s0963-9969(01)00107-7
Commission of the European Communities 2002 Commission regulation (EC) No. 221/2002 of 6 February 2002 amending regulation (EC) No. 466/2002 setting maximum levels for certain contaminants in food stuffs Off J Eur Commun Brussels 6 February 2002
Di benedetto R , Attorri L , Salvati S , Leonardi F , Di biase A 2007 Eicosapentaenoic acid stimulates leptin receptor gene expression in the hypothalamus of newborn rats Nutr Res 27 367 - 371    DOI : 10.1016/j.nutres.2007.04.013
Domingo JL , Bocio A , Marti-Cid R , Llobet JM 2007 Benefits and risks of fish consumption Part II. RIBEPEIX, a computer program to optimize the balance between the intake of Omega-3 fatty acids and chemical contaminants Toxicology 230 227 - 233
Dural M , Ziya Lugal Goksu M , Ozak AA 2007 Investigation of heavy metal levels in economically important fish species captured from the Tuzla lagoon Food Chem 102 415 - 421    DOI : 10.1016/j.foodchem.2006.03.001
Eastwood S , Couture P 2002 Seasonal variations in condition and liver metal concentrations of yellow perch (Perca flavescens) from a metal-contaminated environment Aquat Toxicol 58 43 - 56    DOI : 10.1016/s0166-445x(01)00218-1
Food and Environmental Hygiene Department (FEHD) of the Hong kong Government 1983 Food Adulteration (Metallic Contamination) Regulations, cap 132V Laws of Hong Kong Hong Kong, CN
Gilbert RJ , Louvois JD , Donovan T , Little C , Nye K , Ribeiro CD , Richards J , Roberts D , Bolton FJ 2000 Guidelines for the microbiological quality of some ready-to-eat foods sampled at the point of sale Commun Dis Public Health 3 163 - 167
Grigorakis K , Taylor KDA , Alexis MN 2003 Organoleptic and volatile aroma compounds comparison of wild and cultured gilthead sea bream (Sparus aurata): sensory differences and possible chemical basis Aquaculture 225 109 - 119    DOI : 10.1016/s0044-8486(03)00283-7
Harris WS 1997 n-3 fatty acids and serum lipoproteins human studies Am J Clin Nutr 65 1645S - 1654S
Hong SI , Pyun YR 1999 Inactivation kinetics of Lactobacillus plantarum by high pressure carbon dioxide J Food Sci 64 728 - 733    DOI : 10.1111/j.1365-2621.1999.tb15120.x
International Council for the Exploration of the Sea (ICES) 1988 Results of 1985 baseline study of contaminant in fish and shellfish ICES Coop Copenhagen, DK
Isenschimid A , Marison IW , Vonstockar U 1995 The influence of pressure and temperature of compressed CO2on the survival of yeast cells J Biotechnol 39 229 - 237    DOI : 10.1016/0168-1656(95)00018-l
Jose LD , Ana B , Gemma F , Llobet JM 2007 Benefits and risks of fish consumption: part I. A quantitative analysis of the intake of omega-3 fatty acids and chemical contaminants Toxicology 230 219 - 226
Josephson DB , Maarse H 1991 Seafood. In: Volatile Compounds in Foods and Beverages Dekker Inc New York, US 179 - 202
Josephson DB , Lindsay RC , Stuiber DA 1984 Biogenesis of lipid-derived volatile aroma compounds in the emerald shiner (Notropisatherinoides) J Agric Food Chem 32 1347 - 1352    DOI : 10.1021/jf00126a032
Kanai G , Kato H , Umeda N , Okada K , Matsuzaki M 2010 Drying condition and qualities of rapeseed and sunflower JARQ 44 173 - 178    DOI : 10.6090/jarq.44.173
Khalifa KM , Hamil AM , Al-Houni AQA , Ackacha MA 2010 Determination of heavy metals in fish species of the Mediterranean sea (Libyan coast line) using atomic absorption spectrometry Int J Chem Tech Res 2 1350 - 1354
Kraus-etschmann S , Shadid R , Campoy C , Hoster E , Demmelmair H , Jimenez M , Gil A , Rivero M , Veszpremi B , Decsi T , Koletzko BV 2007 Effects of fish oil and folate supplementation of pregnant women on maternal and fetal plasma concentrations of docosahexaenoic acid and eicosapentaenoic acid: a European randomized multicenter trial Am J Clin Nutr 85 1392 - 1400
Lee MK , Uddin MS , Chun BS 2008 Off flavors removal and storage improvement of mackerel viscera by supercritical carbon dioxide extraction J Environ Biol 29 591 - 597
Methven L , Tsoukka M , Oruna-Concha MJ , Parker JK , Mottram DS 2007 Influence of sulfur amino acids on the volatile and nonvolatile components of cooked salmon (Salmo salar) J Agric Food Chem 55 1427 - 1436    DOI : 10.1021/jf0625611
Ministry of Public Health, Thailand (MPHT) 1986 Residues in foods. In: Special Issue, 16 February The Government Gazette Bangkok, TH 1123 - 1124
O’Connor DL , Hall R , Adamkin D , Auestad N , Castillo M , Conner WE , Connor SL , Fitzgerald K , Groh-Wargo S , Hartmann EE , Jacobs J , Janowsky J , Lucas A , Margeson D , Mena P , Neuringer M , Nesin M , Singer L , Stephenson T , Szabo J , Zemon V 2001 Growth and development in preterm infants fed long-chain polyunsaturated fatty acids: a prospective, randomized controlled trial Pediatrics 108 359 - 371
Peralta RR , Shimoda M , Osajima Y 1996 Further identification of volatile compounds in fish sauce J Agric Food Chem 44 3606 - 3610    DOI : 10.1021/jf9603036
Ping S , Peilong S , Yanjie Y 2008 response surface optimization of wheat germ oil yield by supercritical carbon dioxide extraction J Food Bioprod Process 86 227 - 231    DOI : 10.1016/j.fbp.2007.04.001
Piveteau F , Le Guen S , Gandemer G , Baud J-B , Prost C , Demaimay M 2000 Aroma of fresh oysterscrassostrea gigas: composition and aroma notes J Agric Food Chem 48 4851 - 4857    DOI : 10.1021/jf991394k
Roh HS , Park JY , Park SY , Chun BS 2006 Isolation of off flavors and odors from tuna fish oil using supercritical carbon dioxide Biotechnol Bioprocess Eng 11 496 - 502    DOI : 10.1007/bf02932073
Seo YS , Lee JK 2010 Simultaneous analyses for trace multi-odorous and volatile organic compounds in gas using a triple-bed adsorbent tube Korean Chem Eng Res 48 244 - 252
Turkmen A , Türkmen M , Tepe Y , Akyurt I 2005 Heavy metals in three commercially valuable fish species from Iskenderun Bay, northern East Mediterranean Sea, Turkey Food Chem 91 167 - 172    DOI : 10.1016/j.foodchem.2004.08.008
USFDA 1993 Guidance Document for Arsenic in Shellfish DHHS/PHS/FDA/CFSAN/Office of Seafood Washington, DC, US
Yılmaz F , Ozdemir N , Demirak A , Tuna AL 2007 Heavy metal levels in two fish speciesLeuciscus cephalusandLepomis gibbosus Food Chem 100 830 - 835    DOI : 10.1016/j.foodchem.2005.09.020