Quality Assessment of Fish Oil Obtained after Enzymatic Hydrolysis of a Mixture of Rainbow Trout (Oncorhynchus mykiss) and Atlantic Salmon (Salmo salar) Rest Raw Material Pretreated by High Pressure.

Utilization of fish rest raw material for fish oil extraction has received interest with the increasing demand for sustainable food sources. Enzymatic hydrolysis is an efficient method for the extraction of value-added compounds, but its effectiveness may be enhanced by high-pressure processing (HPP). However, HPP can induce lipid oxidation, affecting the quality of the oil. This study aimed to evaluate the quality of fish oil obtained after enzymatic hydrolysis of a mixture of rainbow trout (Oncorhynchus mykiss) and Atlantic salmon (Salmo salar) rest raw material pretreated by HPP. Six pretreatments were tested prior to enzymatic hydrolysis; 200 MPa × 4 min, 200 MPa × 8 min, 400 MPa × 4 min, 400 MPa × 8 min, 600 MPa × 4 min, and 600 MPa × 8 min. The oil samples were analyzed for lipid oxidation parameters, free fatty acid content, fatty acid composition, and color changes over 8 weeks. The results confirmed that HPP may induce lipid oxidation and revealed significant influence of HPP parameters on lipid oxidation, with higher pressures leading to increased oxidation. Fatty acid composition varied among samples, but it was not substantially affected by HPP.

Safety assessment of fish oil green extraction and in vivo acute toxicity evaluation.

Sardine co-products can represent an interesting source of bioactive compounds, such as polyunsaturated fatty acids and in particular omega-3. This study aimed to investigate extraction of oil from sardine co-products by enzymatic hydrolysis using two proteases: commercial Alcalase and protease Bb from a local fungal strain (P2) of Beauveria bassiana, which overproduces proteases. Despite a higher degree of hydrolysis (41.34%) than Alcalase (24.28%), protease Bb allowed the extraction of approximately the same oil content. Resulting oil from both processes had the same fatty acid profile. Interestingly, the all-produced oil displayed an attractive w6/w3 ratio, an indicator of nutritional quality, of the order of 0.16. The safety of the generated oils was also assessed by treating two groups of Wistar rats with the fish oil administered by oral gavage at the doses (30 mg/kg and 300 mg/kg body weight) for 14 days using olive oil as a vehicle. Compared to controls used, both treated groups showed no statistically significant differences. Consequently, the acute oral toxicity evaluated by hematological, biochemical, and histological studies showed the safety of the oil generated using B. bassiana protease.

Assessment of the safety of dietary fish oil supplements in terms of content and quality.

The fatty acid composition of top-selling fish oil dietary supplements in the markets was compared with the content stated on product label, and their oxidative qualities and heavy metal contents were evaluated in this study. While all the capsule groups (C) confirmed the label information, it was observed that one-third of the syrup groups (S) had less than the specified content. Capsule groups generally had richer EPA and DHA contents than syrup groups in the samples examined. The peroxide values (PV) of all fish oil capsules and syrups were found in the range of 1.97-2.89 mEq/kg and 2.22-18.30 mEq/kg, respectively. As for free fatty acids (FFA) values, the C4, S6, S9, and S10 groups were above the 3% oleic acid limit recommended for high-quality oils. However, thiobarbituric acid reactive substances (TBARs) values were found below 1 mg MA/kg in all groups. All fish oil supplements were within the limits specified in terms of As (0.50-4.19 µg/g), Cd (0.14 µg/g detected for one group, C5), Cu (not detected), Fe (0.32-15.7 µg/g), and Hg (≤ 0.1 µg/g). On the other hand, two fish oil supplements from the capsule group (0.17 for C6 and 1.01 µg/g for C8) and one group from the syrup group (0.29 µg/g for S10) exceeded the recommended limit in terms of Pb (0.1 mg/kg). As a result of the research, it can be concluded that the chemical quality of fish oils in syrup form needs to be improved and their reliability in terms of fatty acid content should be increased. Considering the heavy metals, it seems significant to follow up the fish oil products more strictly.

From Fish Waste to Value: An Overview of the Sustainable Recovery of Omega-3 for Food Supplements.

The disposal of food waste is a current and pressing issue, urging novel solutions to implement sustainable waste management practices. Fish leftovers and their processing byproducts represent a significant portion of the original fish, and their disposal has a high environmental and economic impact. The utilization of waste as raw materials for the production of different classes of biofuels and high-value chemicals, a concept known as "biorefinery", is gaining interest in a vision of circular economy and zero waste policies. In this context, an interesting route of valorization is the extraction of omega-3 fatty acids (ω-3 FAs) for nutraceutical application. These fatty acids, such as eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) have received attention over the last decades due to their beneficial effects on human health. Their sustainable production is a key process for matching the increased market demand while reducing the pressure on marine ecosystems and lowering the impact of waste production. The high resale value of the products makes this waste a powerful tool that simultaneously protects the environment and benefits the global economy. This review aims to provide a complete overview of the sustainable exploitation of fish waste to recover ω-3 FAs for food supplement applications, covering composition, storage, and processing of the raw material.

A comparison of accumulation and depuration effect of dissolved hexavalent chromium (Cr6+) in head and muscle of bighead carp (Aristichthys nobilis) and assessment of the potential health risk for consumers.

In this study, bighead carp (Aristichthys nobilis) were exposed to waterborne Cr6+ of 0.01, 0.1, 1 and 5 mg/L for 14 days and subsequently transferred to clean water for another 14 days. The Cr6+ contents in some edible parts, such as dorsal muscle, ventral muscle and head were detected. The Cr6+ concentrations in the three parts were in the order of: head > ventral muscle > dorsal muscle with significant increase during exposure period and remarkable decrease when kept at clean water during depuration stage. The head contained higher fat than that of muscle and the Cr6+ levels of these parts showed significantly positive correlation with fat content, however, the Cr6+ contents in the separated fat were extremely low. The Cr6+ levels determined in tissues can tell a real story rather than the correlation coefficient. Fish head poses a higher potential health risk than muscle due to heavy metals pollution.

Oxidation of fish oil supplements in Australia.

Fish oils oxidise readily, forming primary and secondary oxidation products, which may be harmful for humans. Some recent studies reported that fish oil supplements in Australasia are oxidised above acceptable international limits, however other studies reported low levels of oxidation. This study employed peroxide and p-anisidine values determination to measure primary and secondary oxidation of fish oils in the Australian market. Of 26 supplements tested, 38% exceeded the limit for primary oxidation, 25% exceeded the limit for secondary oxidation and 33% exceeded the limit for total oxidation, according to international recommendations. Four specially marketed supplements were found to deliver significantly lower amounts of fish oil per capsule (165 vs. 577 mg, p = .007), yet cost significantly more on a per gram basis ($2.97 vs $0.39, p < .001). However, there were no differences in any oxidative markers between regular supplements and the specially marketed products.

Fish Oil Protects Wild Type and Uncoupling Protein 1-Deficient Mice from Obesity and Glucose Intolerance by Increasing Energy Expenditure.

SCOPE: The mechanisms and involvement of uncoupling protein 1 (UCP1) in the protection from obesity and insulin resistance induced by intake of a high-fat diet rich in omega-3 (n-3) fatty acids are investigated. METHODS AND RESULTS: C57BL/6J mice are fed either a low-fat (control group) or one of two isocaloric high-fat diets containing either lard (HFD) or fish oil (HFN3) as fat source and evaluated for body weight, adiposity, energy expenditure, glucose homeostasis, and inguinal white and interscapular brown adipose tissue (iWAT and iBAT, respectively) gene expression, lipidome, and mitochondrial bioenergetics. HFN3 intake protected from obesity, glucose and insulin intolerances, and hyperinsulinemia. This is associated with increased energy expenditure, iWAT UCP1 expression, and incorporation of n-3 eicosapentaenoic and docosahexaenoic fatty acids in iWAT and iBAT triacylglycerol. Importantly, HFN3 is equally effective in reducing body weight gain, adiposity, and glucose intolerance and increasing energy expenditure in wild-type and UCP1-deficient mice without recruiting other thermogenic processes in iWAT and iBAT, such as mitochondrial uncoupling and SERCA-mediated calcium and creatine-driven substrate cyclings. CONCLUSION: Intake of a high-fat diet rich in omega-3 fatty acids protects both wild-type and UCP1-deficient mice from obesity and insulin resistance by increasing energy expenditure through unknown mechanisms.

The effect of micronutrient supplementation on growth and hepatic metabolism in diploid and triploid Atlantic salmon (Salmo salar) parr fed a low marine ingredient diet.

The effects of low marine ingredient diets supplemented with graded levels (L1, L2, L3) of a micronutrient package (NP) on growth and metabolic responses were studied in diploid and triploid salmon parr. Diploids fed L2 showed significantly improved growth and reduced liver, hepatic steatosis, and viscerosomatic indices, while fish fed L3 showed suppressed growth rate 14 weeks post feeding. In contrast, dietary NP level had no effect on triploid performance. Whole body mineral composition, with exception of copper, did not differ between diet or ploidy. Whole fish total AAs and N-metabolites showed no variation by diet or ploidy. Free circulating AAs and white muscle N-metabolites were higher in triploids than diploids, while branch-chained amino acids were higher in diploids than triploids. Diploids had higher whole body α-tocopherol and hepatic vitamins K1 and K2 than triploids. Increased tissue B-vitamins for niacin and whole-body folate with dietary NP supplementation were observed in diploids but not triploids, while whole body riboflavin was higher in diploids than triploids. Hepatic transcriptome profiles showed that diploids fed diet L2 was more similar to that observed in triploids fed diet L3. In particular, sterol biosynthesis pathways were down-regulated, whereas cytochrome P450 metabolism was up-regulated. One­carbon metabolism was also affected by increasing levels of supplementation in both ploidies. Collectively, results suggested that, for optimised growth and liver function, micronutrient levels be supplemented above current National Research Council (2011) recommendations for Atlantic salmon when fed low marine ingredient diets. The study also suggested differences in nutritional requirements between ploidy.

Effects of postnatal overfeeding and fish oil diet on energy expenditure in rats.

BackgroudEarly life nutrition may have a role in the regulation of metabolism in adulthood. The present study aimed to evaluate the effects of postnatal overfeeding and a postweaning fish oil diet on energy expenditure.MethodsOn postnatal day 3, rat litters were adjusted to a litter size of three (small litters, SLs) or ten (normal litters, NLs). After weaning, SLs were fed the standard diet or a fish oil diet enriched with polyunsaturated fatty acids (SL-FOs) for 10 weeks. The metabolic parameters of rats were monitored using the TSE LabMaster at postnatal week 3 (W3) and postnatal week 13 (W13).ResultsAt W3, the O2 consumption and heat production in SLs were lower than those in NLs, while the respiratory exchange ratio (RER) was higher than NLs. SLs showed obesity, dyslipidemia, and impaired glucose tolerance at W13. The postweaning fish oil diet in SLs not only increased O2 consumption, CO2 production, heat production, and reduced the RER but it also reduced weight gain, serum triglycerides, and improved glucose tolerance at W13.ConclusionPostnatal overfeeding can decrease the level of body energy expenditure and induce obesity, but a fish oil diet can increase the energy expenditure and prevent the development of metabolic dysregulation in adults.

DHA-rich Fish Oil Increases the Omega-3 Index and Lowers the Oxygen Cost of Physiologically Stressful Cycling in Trained Individuals.

Dietary fish oil, providing docosahexaenoic acid (DHA) modulates oxygen consumption and fatigue in animal models. However, in humans predominately supplemented with high eicosapentaenoic acid (EPA), there is no evidence of endurance performance enhancement. Therefore, this study examined if DHA-rich fish oil could improve repeated bouts of physiologically stressful cycling and a subsequent time trial in a state of fatigue. Twenty-six trained males took part in a double-blind study and were supplemented with either 2 × 1g/day soy oil, Control) or DHA-rich tuna fish oil (Nu-Mega) (FO) (560mg DHA / 140mg eicosapentaenoic acid (EPA), for 8 weeks. Maximal cycling power (3 × 6s), isometric quadriceps strength (MVC), Wingate cycling protocol (6 × 30s) and a 5min cycling time-trial were assessed at baseline and eight weeks. The Omega-3 Index was not different at baseline (Control: 4.2 ± 0.2; FO: 4.7 ± 0.2%) and increased in the FO group after eight weeks (Control: 3.9 ± 0.2; FO: 6.3 ± 0.3%, p < .01). There was no effect of DHA-rich fish oil on power output of maximal 6s cycle sprinting (Control: Pre 1100 ± 49 Post 1067 ± 51; FO: Pre 1070 ± 46 Post 1042 ± 46W), during 5min time trail (Control: Pre 267 ± 19 Post 278 ± 20; FO: Pre 253 ± 16 Post 265 ± 16 W) or maximal voluntary contraction force (Control: Pre 273 ± 19 Post 251 ± 19; FO: Pre 287 ± 17 Post 283 ± 16 Nm). Nevertheless, relative oxygen consumption was reduced the FO group during the cycling time trial (Control: -23 ± 26; FO: -154 ± 59ml O2/min/100W p < .05) suggesting improved economy of cycling. We conclude that DHA-rich fish oil, successful at elevating the Omega-3 Index, and reflective of skeletal muscle membrane incorporation, can modulate oxygen consumption during intense exercise.

A low cost synthesis method for functionalised iron oxide nanoparticles for magnetic hyperthermia from readily available materials.

The synthesis of iron oxide nanocrystals from reagents taken from high street sources using thermal decomposition of an iron-fatty acid precursor in a high boiling point solvent in the presence of surfactants is presented. The nanocrystals were characterised using a variety of techniques including: electron microscopy, X-ray dispersive spectroscopy, infrared spectroscopy, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and magnetometry. Thermogravimetric analysis (TGA) is also used to compare the decomposition behaviour of iron oleate and iron palmitate, our nanoparticle precursors. The nanoparticles also exhibit shape anisotropy when prepared under optimum conditions. We show that these nanoparticles have potential in magnetic hyperthermia after transfer to aqueous media via an amphiphilic polymer.

Supplementation with eicosapentaenoic acid-rich fish oil improves exercise economy and reduces perceived exertion during submaximal steady-state exercise in normal healthy untrained men.

Based on the effects of n-3 polyunsaturated fatty acids (PUFA) such as eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) on reduction of blood viscosity, we theorized that PUFA could improve aerobic performance by increasing oxygen supply to tissues. Twenty male subjects were randomly divided into two groups (n = 10): a fish oil group (FG) and a control (CG). Maximal oxygen uptake and oxygen uptake during submaximal exercise were measured using a cycle ergometer. For 8 weeks, the FG then ingested capsules containing 3.6 g/day of EPA-rich fish oil, while the CG took 3.6 g/day of a medium-chain triglyceride. After supplementation, erythrocyte EPA and DHA in the FG were significantly increased. In the FG, a negative linear correlation was detected in the change between erythrocyte EPA and whole oxygen uptake during submaximal exercise pre- and post-supplementation. The present study showed that EPA-rich fish oil supplementation improves exercise economy in humans.

Optimisation of the supercritical extraction of toxic elements in fish oil.

This study aims to optimise the operating conditions for the supercritical fluid extraction (SFE) of toxic elements from fish oil. The SFE operating parameters of pressure, temperature, CO2 flow rate and extraction time were optimised using a central composite design (CCD) of response surface methodology (RSM). High coefficients of determination (R²) (0.897-0.988) for the predicted response surface models confirmed a satisfactory adjustment of the polynomial regression models with the operation conditions. The results showed that the linear and quadratic terms of pressure and temperature were the most significant (p < 0.05) variables affecting the overall responses. The optimum conditions for the simultaneous elimination of toxic elements comprised a pressure of 61 MPa, a temperature of 39.8ºC, a CO2 flow rate of 3.7 ml min⁻¹ and an extraction time of 4 h. These optimised SFE conditions were able to produce fish oil with the contents of lead, cadmium, arsenic and mercury reduced by up to 98.3%, 96.1%, 94.9% and 93.7%, respectively. The fish oil extracted under the optimised SFE operating conditions was of good quality in terms of its fatty acid constituents.

A nutritional-toxicological assessment of Antarctic krill oil versus fish oil dietary supplements.

Fish oil dietary supplements and complementary medicines are pitched to play a role of increasing strategic importance in meeting daily requirements of essential nutrients, such as long-chain (≥ C20, LC) omega-3 polyunsaturated fatty acids and vitamin D. Recently a new product category, derived from Antarctic krill, has been launched on the omega-3 nutriceutical market. Antarctic krill oil is marketed as demonstrating a greater ease of absorption due to higher phospholipid content, as being sourced through sustainable fisheries and being free of toxins and pollutants; however, limited data is available on the latter component. Persistent Organic Pollutants (POP) encompass a range of toxic, man-made contaminants that accumulate preferentially in marine ecosystems and in the lipid reserves of organisms. Extraction and concentration of fish oils therefore represents an inherent nutritional-toxicological conflict. This study aimed to provide the first quantitative comparison of the nutritional (EPA and DHA) versus the toxicological profiles of Antarctic krill oil products, relative to various fish oil categories available on the Australian market. Krill oil products were found to adhere closely to EPA and DHA manufacturer specifications and overall were ranked as containing intermediate levels of POP contaminants when compared to the other products analysed. Monitoring of the pollutant content of fish and krill oil products will become increasingly important with expanding regulatory specifications for chemical thresholds.

Nutritional quality of salmon products available from major retailers in the UK: content and composition of n-3 long-chain PUFA.

In the present study, salmon products available from UK retailers were analysed to determine the levels of n-3 long-chain PUFA (LC-PUFA), a key determinant of nutritional quality. There was a wide variation in the proportions and absolute contents of EPA and DHA in the products. Relatively high contents of 18 : 1n-9, 18 : 2n-6 and 18 : 3n-3, characteristic of vegetable oils (VO), were found in several farmed salmon products, which also had generally lower proportions of EPA and DHA. In contrast, farmed salmon products with higher levels of 16 : 0 and 22 : 1, characteristic of fish oil (FO), had higher proportions of EPA and DHA. Therefore, there was a clear correlation between the levels of VO and FO in feeds and the proportions of n-3 LC-PUFA in products. Although wild salmon products were characterised by higher proportions of n-3 LC-PUFA (20-40%) compared with farmed fish (9-26%), they contained lower total lipid contents (1-6% compared with 7-17% in farmed salmon products). As a result, farmed salmon products invariably had higher levels of n-3 LC-PUFA in absolute terms (g/100 g fillet) and, therefore, delivered a higher 'dose' of EPA and DHA per portion. Overall, despite the finite and limiting supply of FO and increasing use of VO, farmed salmon continue to be an excellent source of and delivery system for n-3 LC-PUFA to consumers.

Assessment of the antioxidant capacity and oxidative stability of esterified phenolic lipids in selected edible oils.

The research work was aimed at the determination of the antioxidant capacity (AOC) and the oxidative stability of phenolic lipids (PLs), obtained by lipase-catalyzed transesterification of phenolic acids (PAs) with selected edible oils (EOs), including flaxseed (FSO), fish liver (FO), and krill (KO) oils. The statistical analyses (Tukey's test at P < 0.05) revealed that the difference in AOC between that of the esterified FSO (EFSO) and the esterified krill oil (EKO) containing PLs and their control trials of EOs was significant (P < 0.05). To evaluate the storage stability, the EOs and their esterified products were subjected to 2 oxidation treatments. The experimental findings showed that the esterified EOs had higher oxidative stability when they were subjected to light, oxygen, and agitation at 50 °C as compared to that of the EOs; however, only the esterified fish oil (EFO) showed a significant difference in its peroxide value, when the esterified EOs were placed in the dark at 25 °C. Overall, the phenolic mono- and diacyglycerols present in the EOs have shown to be potential antioxidants in improving the oxidative stability of the oil and enhancing its AOC.

Parenteral nutrition admixtures for pediatric patients compounded with highly refined fish oil-based emulsion: assessment of physicochemical stability.

Fish oil-based emulsion is increasingly used in pediatric patients receiving Parenteral Nutrition (PN). However, its unique use in children on long-term PN is nutritionally debatable as some patients are better off with a mixture of long-chain (LCT) or long-chain + medium-chain (LCT + MCT) triglycerides along with Fish Oil (FO). Lipid emulsions are safely infused when particle diameter ranges between 0.4 and 1.0 micron (like chylomicra), according to European guidelines. No data exist on Fish Oil stability when added to other PN components typically present in pediatric formulations such as other lipids or micronutrients. Our goal is to evaluate the stability of a highly refined FO-emulsion in PN admixtures containing LCT or LCT + MCT triglycerides and different calcium content. Stability studies were carried out on six PN admixtures having two levels of calcium concentration compounded with olive oil LCT + FO, LCT + MCT + FO emulsion and pure FO alone, respectively. The analyses were performed immediately at time 0 (t = 0) and 24, 48, 72, 96 (t = 96) hours after compounding. Particle diameters were determined by Light Scattering-Reverse Fourier Optics Technique by means of a Laser Granulometer. Every sample was stored at 4 °C and triple tested. Statistical significance was verified by f-test. In all admixtures, physicochemical stability did not change between t = 0 and t = 96 and particle diameters were in the expected range of 0.4-1.0 micron provided calcium concentration remained below 4.5 mmol/L. When calcium exceeded that level, 12% of particle diameters was larger than 1.0 micron and 2% exceeded 5.0 micron immediately after compounding. In particular, admixtures compounded with olive oil LCT + FO emulsion or FO emulsion alone showed lower particle diameters compared to admixture with olive/soybean LCT alone, probably due to a different steric encumbrance of oleic acid and omega-3 fatty acid. In the PN admixtures tested, containing FO-emulsion alone or in combination with olive LCT or LCT + MCT, the fat emulsion appears to be stable and safe for infusion when calcium concentration is maintained below 4.5 mmol/L. If calcium level exceeds 4.5 mmol/L, as often required in premature patients, it is advisable to infuse FO emulsion alone through a second intravenous line.

Stability of omega-3 LC-PUFA-rich photoautotrophic microalgal oils compared to commercially available omega-3 LC-PUFA oils.

Microalgae are the primary producers of omega-3 LC-PUFA, which are known for their health benefits. Their oil may thus be a potential alternative for fish oil. However, oxidative and hydrolytic stability of omega-3 LC-PUFA oils are important parameters. The purpose of this work was therefore to evaluate these parameters in oils from photoautotrophic microalgae (Isochrysis, Phaeodactylum, Nannochloropsis gaditana, and Nannochloropsis sp.) obtained with hexane/isopropanol (HI) and hexane (H) and compare them with commercial omega-3 LC-PUFA oils. When the results of both the primary and secondary oxidation parameters were put together, it was clear that fish, tuna, and heterotrophic microalgae oil are the least oxidatively stable oils, whereas krill oil and the microalgae oils performed better. The microalgal HI oils were shown to be more oxidatively stable than the microalgal H oils. The hydrolytic stability was shown not to be a problem during the storage of any of the oils.