Dietary and seasonal effects on the dorsal meat lipid composition of Japanese (Silurus asotus) and Thai catfish (Clarias macrocephalus and hybrid Clarias macrocephalus and Clarias galipinus)

Muscle proximate composition of various food fish species and their nutritional significance: A review

Today, there is a growing awareness about the importance of eating nutritious foods and fish is gaining momentum as a result of its unique nutritional benefits. Fish are considered as nutritionally valuable part of the human diet because of the presence of both macronutrients (proteins, lipids and ash) and micronutrients (vitamins and minerals). These nutrients are indispensable in human nutrition and have proven to be involved in several metabolic functions. The nutritional content can be used to rank different fish species based on their nutritional and functional benefits, allowing consumers to make better decisions according to their requirements. Proximate composition of fish includes determination of moisture, protein, fat and ash contents, which constitutes about 96%-98% of the total constituents of the fish body. The study of these components gives us a clear understanding in assessing the energy value of the fishes. In the present study, an attempt has been made to provide a concise review about the proximate composition of various fish species from different parts of the world in order to evaluate the high-protein, low-fat food with excellent nutritional values and to enlighten the different exogenous and endogenous factors that are actually responsible for their variation. The review also provides an insight into the characteristics of the chemical composition of various fish species, which are gaining importance for the sector involving fish and fishery products for domestic and foreign trade and for appreciating as animal feed all over the world.

Antioxidant potential and fatty acid profile of fish fillet: effects of season and fish species

The objectives of the present study were to investigate the effect of season and fish species on the antioxidant capacity, fatty acids profile, and vitamin E content of fish fillets from Aras River. The antioxidant potential of hydrophilic and lipophilic extracts of fish fillets was evaluated. The fillet extracts of zander and bream in summer and common carp in winter had the highest antioxidant activity. Palmitic and oleic acids were the major saturated (SFA) and monounsaturated (MUFA) fatty acids, respectively. The fatty acids C22:6n3 and C20:5n3 were the most abundant polyunsaturated (PUFA) fatty acids in all the fishes. In summer, the highest levels of SFA (44.09), total PUFA (25.97), n3 PUFA (20.71) and n3/n6 ratio (4) were found in zander. In winter, the highest amounts of total PUFA and n3 PUFA were determined in silver carp, followed by zander. The highest n3/n6 ratio was also found in silver carp. The ratio of PUFA/SFA was higher in winter than in summer for all the fishes. Vitamin E content of fishes was largely varied. In conclusion, seasonal variation changed the antioxidant potential and fatty acid composition of fish fillets. Aras River fishes, especially zander, possess excellent antioxidant activity and high nutritional quality.

Fatty acid composition of salted and fermented products from Baikal omul (Coregonus autumnalis migratorius)

The fatty acid (FA) composition of raw, salted, and fermented fish products prepared from two populations of Baikal omul (Coregonus autumnalis migratorius) was determined. Total lipid content in the raw, salted, and fermented fish products was 3.85, 4.04, and 3.76%, respectively. Overall, the most abundant fatty acids were 14:0 (myristic acid), 16:0 (palmitic acid), 16:1n-7 (palmitoleic acid), 18:1n-9 (oleic acid), 20:5n-3 (eicosapentaenoic acid), and 22:6n-3 (docosahexaenoic acid, DHA). Polyunsaturated FAs were the main fatty acid group. Among unsaturated FA, n-3 forms dominated. The highest amounts of n-3 FAs were found in raw fish, followed by fermented and salted fish. Salting significantly increased the content of some FAs (15:0, 16:2n-4, 18:3n-3, 20:3n-3) compared with raw fish and decreased the DHA content. The FA composition of fermented fish did not differ from that of raw fish. The n-3:n-6 ratio did not differ between raw, salted, and fermented fish from population A, while the ratio was higher in raw fish from population B. Overall, thiobarbituric acid reactive substances, and thereby oxidation, were significantly lower in raw fish than in salted and fermented fish. Salting, but not fermentation, affected the FA composition of fish.

Effect of season on the fatty acid profile of total lipids, phospholipids and triacylglycerols in

The present study investigated the lipid content and FA profiles of total lipids, phospholipids (PL) and triacylglycerols (TAG) of Mastacembelus mastacembelus from the Atatürk Dam Lake (Turkey). The results showed that the total lipid content of the dorsal muscle varied seasonally from 0.50% to 3.59%. Wide ranges of saturated fatty acids (SFAs) (36.21 to 50.52%) and polyunsaturated fatty acids (PUFAs) (25.22 to 42.02%) were found in the PL fraction. However, higher monounsaturated fatty acids (MUFAs) (37.63 to 45.07%) and SFA (34.71 to 38.82%) were found in TAG (triacylglycerol). The ratios of ω-3 to ω-6 PUFA ranged from 0.65 to 1.32 and 1.07 to 3.48 in PL (phospholipid) and TAG fraction, respectively. The results also showed that the major components were palmitic acid (C16:0), stearic acid (C18:0), oleic acid (C18:1ω-9), palmitoleic acid (C16:1ω-7), docosahexaenoic acid (DHA, C22:6ω-3), arachidonic acid (AA, C20:4ω-6) and docosapentaenoic acid (C22:5ω-3) in total lipid, C16:0, C18:1ω-9, AA and DHA in PL, C16:0, C16:1ω-7, C18:1ω-9, linoleic acid (LA, C18:2ω-6), and DHA in TAG extracted from the muscle of M. mastacembelus in all seasons.

FemaleLeuciscus lepidusMay Be a New Alternative for Fish Oil Supplements

The proximate composition of male and femaleLeuciscus lepidusin Beyşehir Lake was investigated. The fatty acid profiles of total lipid, phospholipid, and triacylglycerol in muscle and liver of male and femaleL. lepiduswere evaluated by gas chromatography. Proximate analyses showed that meat of male and femaleL. lepidushad 15.13 ± 0.04 and 18.75 ± 0.11% fat, 20.42 ± 0.45 and 22.21 ± 0.56% protein, 65.47 ± 1.37 and 61.28 ± 1.03% moisture, and 1.51 ± 0.05 and 1.50 ± 0.03% ash, respectively. The percentage of total saturated fatty acids was higher in liver than in muscle, whereas the total polyunsaturated fatty acid (PUFA) content was the lowest in all fatty acid profiles. The phospholipids contained more PUFAs than triacylglycerol. Analysis of variance indicated significant differences (P<0.05) between male (47.51%) and female (49.98%) muscle PUFAs in total lipid. The proportion of omega 3 (ω3) to omega 6 (ω6) fatty acids of total lipid was 3.15 in male and 3.68 in female. The ratio is an important indicator for comparing the value of fish oil. Therefore, it was concluded thatL. lepiduswas considered to be a high quality product for healthy food choice. Additionally, femaleL. lepidusmay especially be used to produce fish oil supplements from freshwater fish combined with vegetable oils.

Nutritional and lipid profiles in marine fish species from Brazil

Centesimal composition and lipid profiles were evaluated in muscle tissue of four species of Brazilian fish using the Kjeldahl and Bligh & Dyer gravimetric methods and gas chromatography, respectively. The moisture, protein, total lipid, and ash values (g/100g) ranged from 71.13 to 78.39; 18.10 to 19.87; 1.05 to 9.03; and 1.03 to 1.73, respectively. Palmitic acid was prevalent among the saturated fatty acids (10.89-20.38%) and oleic acid was the main monounsaturated acid identified (4.26-15.77%). The eicosapentaenoic-EPA (6.41-10.66%) and docosahexaenoic-DHA (9.12-30.20%) acids were the most prevalent polyunsaturated acids. The average values, which are indicative of nutritional quality, were: Polyunsaturated/saturated (P/S) (1.11-1.47), ω6/ω3 (0.08-0.21), hypocholesterolemic/hypercholesterolemic acid ratios (HH) (0.87-2.43), atherogenicity index (IA) (0.26-0.60), and thrombogenicity index (IT) (0.20-0.44). These results demonstrated that the lipid profiles of the studied species are of nutritional quality.

Proximate composition and lipid stability of dourado (Salminus brasilensis, Cuvier, 1817) fillets exposed to different levels of ammonia and oxygen in vivo

BACKGROUND

The ammonia and oxygen levels of water are physicochemical parameters that affect fish physiology. Thus, we hypothesized that in vivo exposure to stressful ammonia and oxygen levels will affect the post-mortem quality of the fish. Therefore, in this study, the effects of in vivo exposure to stressful ammonia and oxygen levels on the composition and content of thiobarbituric acid reactive substances in fillets from dourado (Salminus brasiliensis) and on the lipid oxidation of these fillets during frozen storage were evaluated.

RESULTS

Short-term exposure (12 h) to stressful environmental conditions (low oxygen and high ammonia levels) did not change the composition of the flesh. However, longer exposure (15 days) to these stressful conditions caused significant changes in the composition of the flesh. Exposure to a stressful ammonia level before slaughtering increased the susceptibility of the fish fillets to lipid oxidation during frozen storage. In contrast, exposure to low oxygen levels did not increase the lipid oxidation rate of the fillets.

CONCLUSION

These results indicate that the in vivo exposure to high ammonia levels may reduce the quality and stability of dourado fillets.

Restriction fragment length analysis of the cytochrome b gene and muscle fatty acid composition differentiate the cryptic flatfish species Solea solea and Solea aegyptiaca

Overlapping external morphometric characters easily confound the flatfishes Solea aegyptiaca and Solea solea (Soleidae) in areas of the Mediterranean Sea where both species live in sympatry. This leads to uncertainties in the fisheries and marketing of the species, in addition to misinterpretations in biogeography and conservation studies. This paper describes a simple restriction fragment length-based diagnostic test that differentiates S. solea from S. aegyptiaca, as well as from other species of the Soleidae family. Furthermore, the two species living in sympatry in the Gulf of Kavala (North Aegean Sea, Greece) present significant qualitative differences in muscle fatty acid composition, a property that can also be used to distinguish the two cryptic species.

Dietary amino acid L-tryptophan requirement of fingerling Indian catfish, Heteropneustes fossilis (Bloch), estimated by growth and haemato-biochemical parameters

An 8-week feeding trial was conducted to determine the dietary tryptophan requirement of fingerling Indian catfish, Heteropneustes fossilis (6.10 ± 1.15 cm, 4.44 ± 0.50 g). Six isonitrogenous (40 g 100 g⁻¹) and isoenergetic (17.90 kJ g⁻¹) amino acid test diets were formulated with gradation of 0.1 g 100 g⁻¹ containing graded levels of L-tryptophan (0.04-0.54 g 100 g⁻¹, dry diet). Fish were stocked in triplicate groups, in 75-L circular trough with flow-through system and fed experimental diets at 4% BW/day twice daily. Maximum live weight gain (258%), best feed conversion ratio (FCR) (1.54) and protein efficiency ratio (PER) (1.62) were obtained in fish fed diet containing 0.34 g 100 g⁻¹ tryptophan. However, quadratic regression analysis of weight gain, FCR, PER and body protein deposition (BPD) data indicated requirements for dietary tryptophan at 0.37, 0.33, 0.32 and 0.33 g 100 g⁻¹ of dry diet, respectively. Significantly (P < 0.05) higher body protein, minimum moisture and intermediate fat contents were recorded at 0.34 g 100 g⁻¹ dietary tryptophan diet. Ash content was not significantly different (P > 0.05) among treatments except for diets 0.04 and 0.14 g 100 g⁻¹. Excellent somatic and haematological indices values were obtained at the requirement level. Based on above results, it is recommended that the diet for H. fossilis should contain tryptophan at 0.32 g 100 g⁻¹, dry diet, corresponding to 0.80 g 100 g⁻¹ dietary protein for optimum growth and efficient feed utilization.

The influence of season on the gonad index and biochemical composition of the sea urchin Paracentrotus lividus from the Golf of Tunis

Seasonal variation in the gonad weight and biochemical composition of the sea urchin Paracentrotus lividus from the Golf of Tunis (Tunisia) were studied between September 2003 and August 2004. The highest gonad indices occurred in March (16.71%). The spawning period occurred between April and July and resulted in a fall in gonad indices to low level (7.12 ± 0.12%). Protein constituted the main component of the gonad, and lipid and carbohydrate were found at appreciable amounts. Consistent with the gonad cycle, sea urchin biochemical components showed clear seasonal variation with a significant decrease during the spawning period. The polyunsaturated fatty acid (PUFA) group was found at high level (40% of the total fatty acids). Of the PUFA group, eicosapentaenoic (C20:5 n − 3) and eicosatetraenoic (C20:4 n − 3) were the most abundant gonadal lipids. The level of PUFA was significantly affected by temperature variation showing an increase during the cold months and a decrease in the hot months.

Fatty liver induced by free radicals and lipid peroxidation

An excessive accumulation of fat in the liver leads to chronic liver injury such as non-alcoholic fatty liver disease (NAFLD), which is an important medical problem affecting many populations worldwide. Oxidative stress has been implicated in the pathogenesis of NAFLD, but the exact nature of active species and the underlying mechanisms have not been elucidated. It was previously found that the administration of free radical-generating azo compound to mice induced accumulation of fat droplet in the liver. The present study was performed aiming at elucidating the changes of lipid classes and fatty acid composition and also measuring the levels of lipid peroxidation products in the liver induced by azo compound administration to mouse. The effects of azo compound on the liver were compared with those induced by high fat diet, a well-established cause of NAFLD. Azo compounds given to mice either by intraperitoneal administration or by dissolving to drinking water induced triacylglycerol (TG) increase and concomitant phospholipid decrease in the liver, whose pattern was quite similar to that induced by high fat diet. Lipid peroxidation products such as hydroxyoctadecadienoic acid and hydroxyeicosatetraenoic acid were increased in the liver in association with the increase in TG. These results show that free radicals as well as high fat diet induce fatty liver by similar mechanisms, in which lipid peroxidation may be involved.

Changes in some components of the muscle lipids of three freshwater fish species under natural extreme cold and temperate conditions

Fatty acid composition, conjugated linoleic acid and cholesterol contents in the muscles of three freshwater fish species (Barbus plebejus escherichi, Capoeta capoeta capoeta and Rutilus rutilus) were determined under natural extreme temperate (July) and cold (January) conditions. The aim of the study was to determine whether there were differences in these components of the muscle lipids among these three fish species under extreme natural conditions. Samples were analyzed using gas chromatography. Palmitic, oleic, docosahexaenoic and eicosapentaenoic acids were the predominant fatty acids in all fish in both months. The percentages of polyunsaturated fatty acids, n - 3 polyunsaturated fatty acids, n - 6 polyunsaturated fatty acids and eicosapentaenoic + docosahexaenoic acids in the muscle of B. plebejus escherichi and C. capoeta capoeta were significantly higher in January (P < 0.05) than in July. The ratio of n - 6 to n - 3 polyunsaturated fatty acids was lower than 0.60 in all fish species, with C. capoeta capoeta showing the lowest ratio in January (0.36). The levels of cholesterol and conjugated linoleic acid ranged from 103.46 to 150.10 mg/100 g oil and from 16.27 to 35.45 mg/100 g oil, respectively, for all samples in both months. There were no statistical differences in cholesterol levels among the three fish species in July and January. Conjugated linoleic acid contents were significantly higher in January in B. plebejus escherichi and C. capoeta capoeta. Of the three species tested, the extreme temperate and cold conditions affected B. plebejus escherichi the most.

Effects of geographic source, rearing system, and season on the nutritional quality of wild and farmed Perca fluviatilis

The effects of season, geographic source (Lake Geneva, Rhine River), and rearing system (extensive, semiextensive, and intensive systems) on the lipid content and FA composition of fillets of Perca fluviatilis were studied. Significant differences in the total lipid content were found between fish coming from the Rhine River and Lake Geneva (1.21 and 1.48%, respectively). Seasonal effects were investigated quarterly for perch sampled in the Rhine River. Intensively reared perch displayed a higher lipid content (1.48%) than the other farmed perch, i.e., 1.26% for a semiextensive system and 1.16% for an extensive system. No significant difference in lipid content was found (i) between lacustrine fish and intensively reared fish or (ii) among fish from the Rhine River and the semiextensive or extensive rearing systems. The main FA were 22:6n-3 (DHA, 21.3-37.1% of total FA), 16:0 (17.7-20.2%), 20:5n-3 (EPA, 9.2-13.2%), 18:1 (8.0-11.5%), 20:4n-6 [arachidonic acid (ARA), 1.9-10.7%], 16:1 (4.3-6.0%), and 18:2n-6 (2.1-6.0%). In comparison with perch coming from the Rhine River, the lacustrine fish were characterized by higher total n-6 PUFA and a lower proportion of both total monounsaturated FA (MUFA) and total n-3 PUFA. Among rearing systems, extensively farmed fish had higher n-6 PUFA and lower n-3 PUFA contents. Wild fish showed higher ARA and 18:2n-6 than farmed fish. They also had significantly more EPA (12.5-13.2%) than farmed perch (9.2-10.9%). For DHA, no difference existed between (i) the lacustrine fish (31.9% of total FA) and the intensively reared fish (33.0%) and (ii) the Rhine (37.1%) and semiextensively reared fish (36%). Effects of size, diet composition, and environmental conditions on the total lipid contents and FA composition are discussed.