Seasonal changes in the proximate chemical compositions and fatty acids of chub mackerel (Scomber japonicus) and horse mackerel (Trachurus trachurus) from the north eastern Mediterranean Sea

The effects of seasonal variations on the proximate chemical compositions and fatty acid profiles of chub mackerel (Scomber japonicus) and horse mackerel (Trachurus trachurus) captured in the north‐eastern Mediterranean Sea were investigated. Protein fluctuations were observed in two species for all seasons. The lipid content of both species was lower in winter than in autumn and spring. In all seasons, the major fatty acids in both species were observed to be palmitic acid (16:0), stearic acid (18:0), oleic acid (18:1 ω9), eicosapentaenoic acid (20:5 ω3) and docosahexaenoic acid (20:6 ω3). Chub mackerel and horse mackerel exhibited seasonal fluctuations in their fatty acid contents. The fatty acid profile of the two species had a higher degree of unsaturation during winter. The levels of EPA in chub mackerel in winter, spring and autumn were 5.96%, 4.86% and 4.33%, respectively, while those of DHA were 24.94%, 18.75% and 17.12%, respectively. The levels of EPA in horse mackerel in winter, spring and autumn were 5.42%, 5.03% and 4.86%, respectively, while those of DHA were 14.96%, 13.31% and 11.10%, respectively. The PUFA (polyunsaturated fatty acids) values and ω3/ω6 ratios in the two species were highest in winter. The results indicate that chub mackerel and horse mackerel captured in the north‐eastern Mediterranean Sea, which are among the most important fish in Turkey and of international commercial value, are a good source of nutrition for human consumption in terms of their proximate chemical composition and fatty acids.     

Chemical compositions and fatty acid profiles of three freshwater fish species

This study investigated the chemical composition and fatty acid profiles of Cyprinus(C) carpio, Labeo(L) rohita and Oreochromis(O) mossambicus from the Indus River, Pakistan. Significant differences were observed for most chemical components and fatty acids (P < 0.01) in the examined fish species. O. mossambicus,C. carpio and L. rohita were high in saturated, mono-unsaturated and poly-unsaturated fatty acids, respectively. Palmitic acid was the most abundant fatty acid in all species ranging from 32% to 46%. Although these fish contained reasonable amounts of essential PUFA such as docosahexaenoic, eicosapentaenoic and arachidonic acids, L. rohita contained the highest amounts of PUFA and protein. These fish contained appreciable levels of Omega-6 PUFA suggesting that these fish especially L. rohita could be used as a source of healthy diet for humans. These findings may benefit the fishing industry, nutritionists and researchers who are striving to improve the nutritive value, processing and marketing of selected fish species.     

Effects of cooking methods on the proximate,mineral and fatty acid composition of European eel (Anguilla anguilla)

The influence of microwave cooking and traditional cooking methods such as baking, grilling and frying on the nutritional composition of eels (Anguilla anguilla) was studied. All methods reduced moisture and increased the protein and fat content. Although the potassium and sodium content of fish cooked by different methods decreased significantly (P = 0.000), the calcium and magnesium content increased. The zinc content of the fish was not affected by cooking. The manganese and iron content significantly increased only in fried fish. The copper content was increased by grilling and microwave cooking. The proportion of saturated fatty acids and monounsaturated fatty acids in cooked fish decreased. Omega‐3 polyunsaturated fatty acids were increased by all cooking methods. The grilling and microwave‐cooking methods were the most suitable considering the n3/n6 ratio and eicosapentaenoic acid levels. The increase in the docosahexaenoic acid level of fried fish enhanced its nutritional value.     

Comparative assessment of proximate composition,physicochemical parameters,fatty acid profile and mineral content in farmed and wild rainbow trout (Oncorhynchus mykiss)

This study was conducted to determine differences between farmed and wild rainbow trout in terms of proximate and fatty acid composition, physicochemical parameters and mineral content. Fat content of farmed fish fillets was higher, while moisture content was lower than wild fish. However, wild fish had higher pH value and water‐holding capacity comparing to farmed fish. The muscle lipids of farmed fish contained higher proportions of 20:0, 18:1n‐9 and 20:1n‐9; and lower proportions of 18:2n‐6, 20:2cis, 18:3n‐3, 20:3n‐6, 20:4n‐6, 20:5n‐3 and 22:6n‐3 fatty acids than wild fish. The percentage of total saturated fatty acids (SFAs) was similar in both fish. Total polyunsaturated fatty acids (PUFAs), n‐3 PUFAs and n‐3/n‐6 PUFAs ratio were higher in the wild fish comparing to farmed fish, whereas its total monounsaturated fatty acids (MUFAs) and n‐6 PUFAs contents were lower. Among the seventeen minerals analysed in fish flesh, differences existed between farmed and wild rainbow trout in Ca and Fe contents. Moreover, toxic trace minerals (As, Cd, Pb and Hg) were all present in amounts below their toxic levels. The differences observed between farmed and wild fish may be attributed to the diet constituents and environmental conditions of the fish.     

Fatty acid profile and proximate composition of Pacific mullet (Mugil so‐iuy) caught in the Black Sea

This study demonstrates proximate composition and fatty acid profile of Pacific mullet caught in Turkey. The highest moisture and protein contents were observed with muscle tissues as 83.74 and 10.52%, while the highest fat and ash contents were attributed to female gonads as 11.80 and 0.94%, respectively, with a significant variation amongst months (P < 0.05). Significant variation (P < 0.05) usually occurred amongst months within the same sex for total saturated fatty acids ( ∑ SFA), monosaturated fatty acids ( ∑ MUFA), polyunsaturated fatty acids ( ∑ PUFA), eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) in muscle, although overall mean values between sexes were not found significant. Except for EPA, no variation observed for gonads while significant changes occurred (P < 0.05) with liver samples amongst months. Overall total values of ∑ SFA, ∑ MUFA, ∑ PUFA, DHA and EPA in muscle samples were 29.59, 29.26, 18.06 and 4.48%, respectively, while in gonads ranged as 30.26–33.23%, 35.17–37.47%, 11.87–14.88%, 4.38–5.34% and 3.02–5.02%. These FAs were 21.57–33.11%, 32.89–50.96%, 14.78–20.08%, 0.89–9.94% and 5.85–9.54% for liver, respectively. The results of this study showed that muscle and gonads of Pacific mullet were rich in n‐3 PUFA, especially, EPA, DHA, increasing the value of this species for human consumption.     

Determination of proximate composition,fatty acid content and amino acid profile of five lesser‐common sea organisms from the Mediterranean Sea

Proximate composition, fatty acid and amino acid analysis of an echinoderm (Paracentrotus lividus), a crustacean (Penaeus kerathurus), a tunicate (Microcosmus sulcatus), and two gastropod molluscs (Littorina littorea and Patella coerulea) were determined. All organisms except M. sulcatus, were found to be good protein sources. P. lividus contained on average 15.1 g/100 g, P. kerathurus 15.6 g/100 g, L. littorea 8.3 g/100 g and P. coerulea 9.2 g/100 g protein. The crustacean contained high percentages of n‐3 fatty acids (28.3 g/100 g fatty acids), the tunicate high percentages of saturated fatty acids (62.2 g/100 g fatty acids) while the gastropod molluscs and the echinoderm had a balanced content of all fatty acid families. The most abundant amino acid in P. kerathurus, M. sulcatus, L. littorea and P. coerulea was glutamic acid (11.13 ± 0.9, 1.05 ± 0.3, 5.39 ± 0.3, 5.55 ± 0.8 g/100 g freeze‐dried sample respectively), while glycine was the most abundant amino acid in P. lividus (10.34 ± 1.0 g/100g freeze‐dried sample).     

Effect of season on heavy metal contents and chemical compositions of chub mackerel (Scomber japonicus) muscle

Seasonal variations of heavy metals concentrations and overall chemical compositions were determined in chub mackerel caught in the Southern Sea of Korea. The average mercury and lead content varied between 0.04 and 0.08 mg/kg and between 0.01 and 0.02 mg/kg, respectively. Seasonal variations were not detected in lead, but mercury displayed maximal values in winter (P < 0.05). A distinct seasonal pattern was found in crude fat content with maximal values in December and minimal values in April. Fatty acid composition showed that monounsaturated fatty acids levels were the highest in August, while polyunsaturated fatty acids (PUFA) levels were the highest in April. The major contributing factors to the seasonal variation of PUFA amounted to 20:5n-3 and 22:6n-3. The total amino acids content varied from 180.6 to 187.7 mg/g. There were no significant seasonal variations in total amounts of amino acids. Practical Application: Mackerel (Scomber japonicus) is one of the most important fishing resources in Korea. The effects of polyunsaturated fatty acids (PUFA) on the human body have been identified, and consequently, the intake of fish lipids has steadily increased among the human population. There have been few studies on safety and alterations in chemical composition of mackerel attributed to seasonal fluctuations. Therefore, the results presented in this study could be used to improve the safety and nutrition information available to consumers.     

Change in proximate, amino acid and fatty acid contents in muscle tissue of rainbow trout (Oncorhynchus mykiss) after cooking

Changes in proximate, amino acid and fatty acid composition of farmed, commercially important rainbow trout (Oncorhynchus mykiss) after conventional and microwave cooking were analysed. Rainbow trouts cooked in microwave ovens had statistically significant higher total protein, total fat, and ash than electrical oven‐cooked samples. The amounts of essential and nonessential amino acids were not different between cooking methods, but the difference between raw and cooked samples was significant. Lysine, leusine, methionine, threonine, valine, arginine and histidine were found most in microwave‐cooked rainbow trouts whereas isoleucine, tyrosine and phenylalanine were found most in electrical oven‐cooked samples. As total saturated fatty acid and total monounsaturated fatty acids amount were not statistically different between the cooking methods, the difference between raw and cooked fillets was found statistically significant (P < 0.05). There was no statistically significant difference between raw and cooked fillets in total n‐3 and n‐6 contents.     

Variations in proximate composition and fatty acid profiles of Baltic sprat (Sprattus sprattus balticus)

The variability of the proximate composition and fatty acid profiles in samples of sprat (Sprattus sprattus balticus) from the southern Baltic Sea were studied in relation to the catch season and location, individual fish size, and sex. Fatty acid profiles depended on such features as fish size and lipid content, which depend on the season of the year in which the fish were caught. No differences in fatty acid profiles were noted between the sexes in the individuals examined. Studies on fish lipids are necessary as fish lipids are important in the prevention of cardiac disease. One of the chief advantages of fish lipids that is relevant to the prevention of cardiac disease is their n−3 to n−6 fatty acid ratio. The most advantageous ratio of these fatty acids was noted in sprat that were the smallest in length.     

Fatty acid composition of green crab (Carcinus mediterraneus) from the Tunisian mediterranean coasts

Green crab (Carcinus mediterraneus) was analysed for proximate and fatty acid composition. The yields of crab claw meat and hepatopancreas were 24.9–26.1% and 8.8–9.2%, respectively. Crude protein (NX6.25) and crude fat contents of crab claw meat were 17.8–18.2% and 0.85–1%, respectively, on a dry weight basis, while those of hepatopancreas were 13–14% and 21.8–22.7%, respectively. The fatty acid (FA) profiles were significantly different between claw meat, and hepatopancreas of the crab. The percentage of total saturated fatty acids was higher in the hepatopancreas (25.15–26.24% of total FAs) than in the claw meat (22.58–23.49% of total FAs). The main saturated fatty acids were palmitic acid (16:0) and stearic acid (18:0). Palmitic acid represented 11.5–12.45% and 11–11.5% of the total FAs in the hepatopancreas and in the claw meat, respectively. The percentages of stearic acid were 7.8–8.3% and 7–7.3% in the hepatopancreas and in the claw meat, respectively. Meanwhile, oleic acid (18:1) was the dominant monounsaturated fatty acid which represents 16.15–16.85% and 15.4–15.7% of the hepatopancreas and the claw meat total FAs, respectively. The dominant PUFA was arachidonic acid (20:4n-6) in both claw meat and hepatopancreas. The content of arachidonic acid (20:4n-6) was higher in the hepatopancreas (13–13.5%) than in the claw meat (10.5–11.8%).     

Comparison of proximate composition,amino acid and fatty acid profiles in wild,pond‐ and cage‐cultured longsnout catfish (Leiocassis longirostris)

The proximate composition, amino acid and fatty acid profiles in the fillets of wild, pond‐ and cage‐cultured longsnout catfish (Leiocassis longirostris) were determined to identify nutritional differences. Wild fish showed higher (P < 0.05) moisture and viscerosomatic index (VSI), but lower (P < 0.05) protein, ash and gross energy than cage‐cultured fish. Pond‐cultured fish contained lower (P < 0.05) protein and ash contents, but higher VSI compared to cage‐cultured fish. The amino acid of glycine content was higher (P < 0.05) in wild fish than in pond‐ and cage‐cultured fish. Most of the fatty acids had a significant difference among all fish groups. The percentages of total polyunsaturated fatty acids (∑ PUFAs) were higher (P < 0.05) in wild and pond‐cultured fish than in cage‐cultured fish. Pond‐cultured fish had higher (P < 0.05) ∑ n‐3 PUFAs, eicosapentaenoic acid (EPA), docosahxaenoic acid (DHA) and ∑ n‐3/∑ n‐6 PUFAs ratio than wild and cage‐cultured fish. The differences among the wild, pond‐ and cage‐cultured fish may be attributed to dietary components and environmental conditions of the fish.     

The effects of industrial pre-frying and domestic cooking methods on the nutritional compositions and fatty acid profiles of two different frozen breaded foods

This study was carried out to determine the effects of manufacturer pre-frying in olive and sunflower oil, as well as domestic cooking methods (deep-frying in olive and sunflower oil and baking) on the proximate compositions and fatty acid profiles of tuna pasties and ham nuggets. The pre-frying processes reduced moisture and carbohydrates and increased ash, fat and protein content in both pre-fried products. During cooking, the frying processes caused a reduction in moisture content and an increase in fat content in relation to pre-fried samples, while baking did not modify the proximate composition. The fatty acid profiles of products during both the pre-frying and frying processes became similar to those of the culinary fat used. Thus, the frying processes reduced the proportion of saturated fatty acids (SFA) and increased the proportion of monounsaturated fatty acids (MUFA) in the foods when olive oil was used, whereas increased the proportion of polyunsaturated fatty acids (PUFA) in products fried in sunflower oil. The fatty acid profiles of fried samples tended to be more similar to the frying fat than to the pre-frying fat, whereas the fatty acid profiles identified during the pre-frying process for baked products were not significantly modified. Thus, samples pre-fried in olive oil and subsequently baked showed the best proportion of fat content and PUFA/SFA, MUFA + PUFA/SFA and n-6/n-3 ratios of the tested products.     

Effect of season on fatty acid composition and n-3/n-6 ratios of zander and carp muscle lipids in Altinapa Dam Lake

In this study, seasonal variations on total fatty acid composition of carp, Cyprinus carpio, and zander, Sander lucioperca, muscle lipids in Altinapa Dam Lake were determined. Fish samples in 2 seasons (summer and winter) were obtained from Altinapa Dam Lake in Konya, Turkey. Polyunsaturated fatty acids were found to be higher during the cold season than in the hot both in zander and carp. Whereas the Docosahexaenoic acid was high in zander both in summer and winter, in carp it was high only during wintertime. Zander contained more n-3 fatty acids during the cold season compared to carp. Especially, the n-3:n-6 ratios in zander were 3.89 and 3.84 in summer and winter, respectively. In conclusion, seasonal variations affected fatty acid composition of zander and carp in Altinapa Dam Lake.     

Meat quality,proximate composition and muscle fatty acid profile of young llamas (Lama glama) supplemented with hay or concentrate during the dry season

Thirty llamas were used to study the effect of a 90 day feed supplementation on meat quality, chemical composition and muscle fatty acid profile. Treatments were: GR = llama on native pasture until slaughter; GR + SH = like GR, but with overnight free access to barley/alfalfa hay; and GR + SC = like GR, but with overnight free access to a wheat bran/sorghum grain concentrate. The supplementation had no effect on postmortem pH and temperature decline in the Longissimus lumborum muscle (LLM), cooking losses nor Warner–Bratzler shear force values (P > 0.05). Meat from GR + SC llama had higher fat content in LLM (P < 0.05) compared to GR and GR + SH llama. Intramuscular fat from GR + SH llama showed higher (P < 0.01) proportions of polyunsaturated fatty acids, higher (P < 0.05) polyunsaturated fatty acids/saturated fatty acids and desirable fatty acids ratio, lower (P < 0.05) omega-6/omega-3 (n − 6/n − 3) ratio, and higher (P < 0.01) conjugated linoleic acid.     

Amino acid and fatty acid composition of wild sea bass (Dicentrarchus labrax): a seasonal differentiation

Seasonal variations in the amino acid and fatty acid compositions of wild sea bass (Dicentrarchus labrax) captured in the north eastern Mediterranean were investigated. In all seasons, the major amino acids in sea bass fillets were determined to be aspartic acid, glutamic acid and lysine. Methionine, tyrosine and histidine composition of the fillets were lower than those of the other amino acids in all seasons. The ratios of essential (E, g amino acid/16 g N)/nonessential (NE, g amino acid/16 g N) amino acids were observed to be 0.75 for winter, 0.76 for autumn, 0.77 for both spring and summer. Results showed that, sea bass fillets are well-balanced food source in terms of E/NE ratios in all seasons. In addition, seasonal differences in polyunsaturated fatty acid (PUFA) composition of the fillets were observed in all seasons. The major fatty acids of sea bass fillets were observed to be palmitic acid (16:0), oleic acid (18:1ω9), eicosapentaenoic acid (EPA, 20:5ω3) and docosahexaenoic acid (DHA, 22:6ω3). The amounts of EPA+DHA in autumn, winter, spring and summer were determined as 0.16, 0.12, 1.14 and 1.02 g/100 g wet weight, respectively.     

Seasonal variation in the fatty acid composition of three Mediterranean fish – sardine (Sardina pilchardus), anchovy (Engraulis encrasicholus) and picarel (Spicara smaris)

The total fat contents and the fatty acid compositions of three common Mediterranean fish, namely sardine (Sardina pilchardus), anchovy (Engraulis encrasicholus) and picarel (Spicara smaris) were determined at bimonthly intervals for a one-year period. The purpose of this work was to study the seasonal variation of the fatty acids in the three fish that are some of the best sources of n − 3 fatty acids. The fat and fatty acid content of the investigated fish species show a significant seasonal dependency. Two of the fish (anchovy and picarel) have the highest fat content during the late winter – spring period. On the other hand, sardine shows the highest fat concentrations during the spring-early summer period. The fish that showed the highest variation in fatty acid composition was the anchovy. The sardine was found to be the best source of n − 3 fatty acids during the one-year period (35.35 g/100 g fatty acids). Finally the picarel had the highest oleic acid content (on average, 13.89/100 g fatty acids).     

Effects of soybean oil and linseed oil on fatty acid compositions of muscle lipids and cooked pork flavour

This study was conducted to investigate the effects of dietary oil on the fatty acid compositions of the longissimus and biceps brachii muscles and its effects on cooked muscles flavour. Seventy-two crossbred barrows (Duroc×Landrace×Large White), were blocked by weight and randomly assigned to one of three treatments. The three dietary treatments were: (a) no oil supplement (CON); (b) 3% soybean oil supplement (SO3); (c) 3% linseed oil supplement (LO3). Dietary linseed oil and soybean oil significantly increased the contents of C18:3 and C18:2 in the neutral lipids and phospholipids in both longissimus muscle and biceps brachii muscle, respectively. Aroma compounds analysis indicated only few aroma compounds were affected significantly by dietary oil in both cooked longissimus muscle and biceps brachii muscle. The flavour attributes of cooked longissimus muscle and biceps brachii muscle were not influenced by feeding 3% soybean oil. Feeding 3% linseed oil did not deleteriously affect the flavour of cooked longissimus muscle but cooked biceps brachii muscle from LO3 had significantly lower pork flavour and higher abnormal flavour than CON and SO3.     

Changes of proximate and fatty acid compositions of the dorsal and ventral ordinary muscles of the full-cycle cultured Pacific bluefin tuna Thunnus orientalis with the growth

Using the full-cycle cultured (FC) Pacific bluefin tuna, Thunnus orientalis [body weights: 13.1 ± 4.5 (FC1; April in 2004), 20.2 ± 1.8 (FC2; July in 2004), 28.5 ± 6.3 (FC3; November in 2004), 27.0 ± 3.3 (FC4; February in 2005) and 33.5 ± 4.7 kg (FC5; May in 2005), n = 3, respectively] and wild bluefin tuna [33.3 ± 1.5kg (June in 2005), n = 3], proximate and fatty acid compositions of the cephalal (Ce-) and caudal (Ca-) parts of the dorsal (D) and ventral (V) ordinary muscles (OMs) were investigated. Lipid contents of the Ce-DOM and VOMs of FC1-5 increased with growth. In particular, lipid content of the Ce-DOM (23.0%) and VOMs (55.1%) of FC5 was higher (P < 0.05) than those of wild tuna [D-(2.0%) and VOMs (16.2%)]. However, lipid contents of the Ca-DOM and VOMs of FC1-5 did not change with growth. On the other hand, the fatty acid compositions of the Ce-DOM and VOMs of FC2-5 resembled each other. However, there was no specific tendency of the changes of each fatty acid composition of the Ce-DOM of FC tuna with growth. On the other hand, total monounsaturated fatty acid content (30.1%) of the Ce-DOM of FC5 was higher (P < 0.05) than that (25.5%) of wild tuna. The ratio of n–3: n–6 (9.4%) of the Ce-VOM of FC5 was lower (P < 0.05) than that (14.0%) of wild tuna. However, the fatty acid compositions of the Ce-DOM and VOMs of FC tuna were not reflected by those of feed (whole fish bodies of sesame mackerel).     

Influence of feeding state and frozen storage temperature on the lipid stability of Atlantic mackerel (Scomber scombrus)

Lipid deterioration of mackerel caught in Icelandic waters was studied, as affected by different frozen storage temperatures (?18 °C vs. ?25 °C) and seasonal variation (August vs. September). The lipid stability was investigated by analyses of hydroperoxide value (PV), thiobarbituric acid reactive substances (TBARS), free fatty acids, as well as changes in fatty acid composition. Results showed significant lipid deterioration with extended storage time, where the lower storage temperature showed significantly more protective effects. Furthermore, a higher lipid oxidation level was recorded for fish caught in September than in August, although lipid hydrolysis occurred to be greater for fish in August than in September. Moreover, results indicated a rather stable level of omega‐3 fatty acid during the whole frozen storage period. The analysis indicated that both lipid oxidation and hydrolysis were affected by the frozen storage temperature and the stability differed with regard to season of catch.     

A comparison of the proximate compositions and fatty acid profiles of zander (Sander lucioperca) from two different regions and climatic conditions

The proximate compositions and fatty acid profiles of the flesh of the fresh water fish zander (Sander lucioperca) obtained from Eğirdir Lake and from Seyhan Dam Lake were compared. The crude protein (18.8–18.1%), ash (1.37–0.75), and dry matter (20.67–20.09) contents of fish in Seyhan Dam Lake were observed to be higher than those in the other lake. Zander in Seyhan Dam Lake had a significantly (p < 0.05) higher lipid content than its Eğirdir counterpart. Differences were also observed in the fatty acid profiles. The percentages of total saturated fatty acids (SFA) and total monounsaturated fatty acids (MUFA) were higher in the zander in Seyhan Dam Lake than in Eğirdir Lake, whereas the corresponding total polyunsaturated fatty acids (PUFA) content was lower. Moreover, the fatty acid composition of these fish showed a relatively high ratio of PUFA/SFA (1.00). Both zanders showed palmitic acid, C16:0, to be predominant, (19.6–20.8%), followed by oleic acid, C 18:1 n − 9, (19.2–13.4%).The data obtained indicate that the % composition of n − 3 PUFAs is greater in the flesh of zander in Eğirdir Lake. This finding is in compliance with the fact that n − 3 fatty acids in fish living in cold climatic conditions have a higher % composition. It was concluded that the consumption of zander, widely found in Eğirdir Lake and having higher % composition of n − 3 PUFAs than those caught from Seyhan Dam Lake, is more beneficial for human health.