Microalga <Emphasis Type="Italic">Isochrysis galbana</Emphasis> in feed for <Emphasis Type="Italic">Trachinotus ovatus</Emphasis>: effect on growth performance and fatty acid composition of fish fillet and liver

Seeking alternatives to the depleting fish oil are crucial for marine fish aquaculture, which is currently dependent on fish oil as the primary source of n-3 long-chain polyunsaturated fatty acids (n-3 LC-PUFAs). Five isonitrogenous (46% crude protein) and isolipidic (16% crude lipid) feed diets (FO, ISO2.9, ISO4.8, ISO6.7, ISO8.6) were formulated by partially replacing fish oil with microalgae Isochrysis galbana. These diets were fed to triplicate tanks of Trachinotus ovatus (mean initial weight 1.92 g) for 80 days. This work demonstrates that a moderate inclusion (around 4.5–5.0 wt%, equivalent to the replacement of 24–26 wt% fish oil) of I. galbana biomass in fish diet improves fish growth performance, lipid deposition and enhances total n-3 fatty acids, DHA, and EPA contents in neutral and polar lipids (PLs) of fish muscle and liver of T. ovatus. The results disclosed in this study suggest that I. galbana microalgae represents a potential high-quality substitute for fish-based ingredients in aquaculture feeds, which can be a promising sustainable solution to resolve the depleting fish oil resource in a cost-effective manner.     

A baseline study on lipid and fatty acid composition in the pearl oyster, <Emphasis Type="Italic">Pinctada fucata</Emphasis>

The pearl oyster Pinctada fucata is cultured for pearl production in China, but its germplasm is degenerated. Thus, lipid and fatty acids were investigated in P. fucata based on different tissues, body sizes and condition indexes using GC–MS to provide a lipidomic baseline for evaluation of breeding variety in terms of physiology. The major fatty acids over all samples included saturated (C16:0 and C18:0), monounsaturated [C16:1(n-7), C18:1(n-7) and C18:1(n-9)], and polyunsaturated fatty acids [arachidonic acid: C20:4(n-6), EPA: C20:5(n-3) and DHA: C22:6(n-3)]. Relative percentages of lipid contents of the mantle and visceral mass were, respectively, 40.75 and 42.03 %, significantly higher than adductor muscle (14.48 %) and gill (17.15 %). Fatty acid analysis showed that there were 15 types of fatty acids in adductor muscle, 17 types in mantle and gill, respectively, and 19 types in visceral mass. Meanwhile, total fatty acids, SFA, MUFA and PUFA were the highest in visceral mass (P < 0.05). Yet the lipid contents and fatty acid compositions showed no significant differences between body sizes or condition indexes based on visceral mass. The observations above suggested that visceral mass and mantle are the major tissues for P. fucata to store lipids and thus are important candidate tissues for lipidomic study.     

The Effect of Thermal Treatment Method on Fatty Acid Composition in Northern Pike (Esox lucius) Fillets

The aim of the present study was to investigate the effect of thermal treatment methods, such as microwave cooking, steaming, and shallow pan-frying on fatty acids composition in northern pike fillets. All methods of thermal treatment increased fat content in the fillets. Microwave cooking decreased the proportion of saturated fatty acids and increased the proportion of total, n-3, and n-6 polyunsaturated fatty acids as compared with fresh fillets. Steam cooking did not affect the proportion of saturated, monounsaturated, and polyunsaturated fatty acids, whereas pan-frying significantly increased the proportion of monounsaturated and n-6 polyunsaturated fatty acids. All cooked fillets, regardless of the thermal treatment used, had acceptable n–6/n–3 ratio; however, microwave cooking enabled fish products to obtain more beneficial n-6/n-3 ratio than frying. Due to high polyunsaturated fatty acids content and low n-6/n-3 ratio, microwave cooking may be recommended for preparing wild pike fillets in households.     

Assessment of Fatty Acid Composition and Technological Properties of Northern Pike (Esox lucius) Fillets: The Effects of Fish Origin and Sex

The aim of the study was to investigate the effects of northern pike origin (wild vs. farmed) and sex (female vs. male) on chemical composition, including fatty acids, and technological properties of fresh fillets. Fish origin influenced moisture, protein, fat, and ash contents, pH and color of the fillets, and the proportion of 22 out of 25 determined fatty acids, whereas sex affected expressible water, pH, lightness and redness of fillets, and only a single fatty acid (C20:0) proportion. Farmed pike had higher protein and fat content and lower moisture and ash than wild pike. Higher proportion and content of total polyunsaturated and n-3 fatty acids, as well as lower n-6/n-3 ratio, were found in farmed pike. Thus, it can be concluded that the commercial feed positively affected fatty acid proportion and content in the fish tissue and increased its nutritional value.     

Effects of starvation and feeding on blood chemistry,fatty acid composition and expression of vitellogenin and fatty acid-binding protein genes in female swimming crab <Emphasis Type="Italic">Portunus trituberculatus</Emphasis> broodstock

Portunus trituberculatus broodstock were stocked in plastic tanks to evaluate the effects of starvation and feeding on gonadal development, blood chemistry, fatty acid composition, and expression of vitellogenin (Vtg) and fatty acid-binding protein genes (FABP) in females. Two treatments (starved and fed) were randomly assigned to triplicate groups of 90 swimming crab broodstock (approximately 230 ± 45 g). In the starved treatment, crabs were starved for 30 days, whereas in the fed treatment crabs were fed once a day with clams. The gonadosomatic index decreased significantly in starved crabs (P < 0.05), as did the serum glucose and cholesterol concentrations; conversely, the total protein concentration in serum significantly increased (P < 0.05). In the ovary, there was a significant relative decline of 18:0, 16:1n-7 and 20:1n-9 fatty acids and relative increases of 20:4n-6, 22:6n-3, 18:1n-9 and 20:5n-3 in starved crabs compared to fed crabs (P < 0.05). Relative expression of Vtg in the ovary decreased significantly in starved crabs (P < 0.05), while there was no significant difference in hepatopancreas Vtg expression between starved and fed crabs (P > 0.05). Starvation suppressed gonadal development in female swimming crab broodstock.     

Effects of different salinities on growth performance,survival, digestive enzyme activity,immune response,and muscle fatty acid composition in juvenile American shad (<Emphasis Type="Italic">Alosa sapidissima</Emphasis>)

The effects of salinity on survival, growth, special activity of digestive enzymes, nonspecific immune response, and muscle fatty acid composition were evaluated in the American shad (Alosa sapidissima). Juveniles of 35 days after hatching were reared at 0 (control), 7, 14, 21, and 28 ppt for 60 days. At the end of the experiment, juvenile American shad presented higher survival and specific growth rate (SGR) in salinity group (7, 14, and 21 ppt) than control group (P < 0.05). The special activity of trypsin and chymotrypsin was highest in fish reared at 21 ppt, while the highest lipase special activity was obtained in control group (P < 0.05). The special activity of alkaline phosphatase (ALP), lysozyme (LZM), superoxide dismutase (SOD), and catalase (CAT) showed significant increases in salinity group (14 and 21 ppt) compared to control group (P < 0.05). Lower muscle ash contents were detected in salinity group (14, 21, and 28 ppt) than control group (P < 0.05), while the contents of crude lipid and crude protein were significantly higher than control group (P < 0.05). The level of monounsaturated fatty acids (MUFA) exhibited a decreasing trend, while an increased level of polyunsaturated fatty acids (PUFA) was detected with the increase of salinity. Among the PUFA, the content of n-3 fatty acids in muscle tissue was found to be increasing with the increasing salinity, especially eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). Results indicate that appropriate increase in salinity was reasonable and beneficial for juvenile American shad culture after a comprehensive consideration, especially salinity range from 14 to 21 ppt.     

Effect of Alpha-Linolenic Acid Sources in Diets for Nile Tilapia on Fatty Acid Composition of Fish Fillet Using Principal Component Analysis

This study evaluated the effect of feed supplementation with chia and canola oils as a substitute for soybean oil on the composition of Nile tilapia muscle tissue using chemometrics. Diets were supplemented with 2.1% of each oil and were provided to fish for 15 and 30 days. Compared to soybean oil, supplementation with canola and chia oils significantly increased (P < 0.05) the contents of eicosapentaenoic acid (EPA, 20:5n-3), docosapentaenoic acid (DPA, 22:5 n-3), and docosahexaenoic acid (DHA, 22:6 n-3) in Nile tilapia fillet. At 30 days, DHA content increased 97% in Nile tilapia fed chia oil and 91% in treatment with canola oil. The highest EPA content correlated to treatment with chia oil (7.33 mg 100 g^?1). The long-chain polyunsaturated fatty acids (LC-PUFAs) precursors, linoleic acid and α-linolenic acid, were observed to increase according to treatment type and feed supplementation duration. The principal component analysis resulted in a two-principal-component model that described 92.07% of the total data variance. Also, it highlighted that the replacement of soybean oil with canola and chia oils in Nile tilapia diets contributed to increasing the n-3 LC-PUFA concentration in Nile tilapia fillets, improving its nutritional value.     

Corn gluten meal in pacu <Emphasis Type="Italic">Piaractus mesopotamicus</Emphasis> diets: effects on growth,haematology, and meat quality

Corn gluten meal (CGM) has a high protein content and absence of antinutrients. However, it has high levels of carotenoids that can cause a yellowing of fish fillets and impair further commercialisation. Graded levels of CGM were incorporated in pacu diets to replace soybean meal (SM) protein. The experimental diets were formulated to be isonitrogenous (220 g kg^?1 digestible protein) and isoenergetic (13.4 MJ kg^?1 digestible energy) with 0, 25, 50, 75, and 100 % replacement of SM protein by CGM protein over a 60-day period. One hundred fish (32.79 ± 3.43 g) were randomly distributed in 20 experimental cages (70 L) placed within five (1000 L) aquaria with continuous water renewal. The experimental design was completely randomised with five treatments and four replicates. A quadratic effect (P < 0.05) was observed for fillet and carcass yields, feed conversion ratio, weight gain, and specific growth rate, with the optimum values for replacement of SM protein by CGM protein estimated as 21.95, 29.13, 30.94, 37.71, and 38.75 %, respectively. There were no differences (P > 0.05) for blood parameters, proximal composition, water-holding capacity, pH, lipid oxidation, and a* value of fillets. The L* and b* values of fillets showed differences (P < 0.05). Replacement between 21.95 and 38.75 % of SM protein by CGM protein (5.37 and 9.48 % of inclusion in the diet) improves the growth performance and body yield of pacu juveniles without altering blood parameters or affecting the fillet quality.     

Deposition of astaxanthin in fillets of Atlantic salmon (Salmo salar) fed diets with herring, capelin, sandeel, or Peruvian high PUFA oils

To elucidate whether absorption and deposition of dietary astaxanthin are influenced by the use of different dietary fish oils having different melting points and fatty acid profiles, triplicate groups of individually labeled Atlantic salmon (initial average weight 569 g) were reared in 2 m² tanks, supplied with saltwater. The fish were fed four different experimental diets coated with either herring oil, capelin oil, sandeel oil, or a Peruvian oil high in polyunsaturated fatty acids. Salmon fed diets containing Peruvian high PUFA oil had significantly higher (13%) fillet carotenoid content than salmon fed herring oil (P<0.05). Astaxanthin retention was significantly higher (P<0.05) in salmon fed capelin and Peruvian high PUFA oil than in the two other groups. The effects of dietary oil supplements on carotenoid deposition were rather small and require verification. Redness of fillets and blood plasma astaxanthin levels did not differ among treatments. Liver weights, body weights, as well as specific growth rates, and feed conversion ratios were unaffected by dietary oil source. Significant (P<0.05) positive linear relationships were found between final fillet idoxanthin concentration and total saturated fatty acids in supplement oils, astaxanthin and total monounsaturated fatty acids, and redness and total n−3 fatty acids, whereas the relationships between redness and total monounsaturated fatty acids and astaxanthin and total n−3 fatty acids were negative.     

Effects of dietary vitamin E supplementation on growth performance,fatty acid composition,lipid peroxidation and peroxisome proliferator-activated receptors (PPAR) expressions in juvenile blunt snout bream <Emphasis Type="Italic">Megalobrama amblycephala</Emphasis>

A 9-week feeding experiment was conducted to evaluate the effects of dietary vitamin E (VE) supplementation on growth performance, liver fatty acid composition, lipid peroxidation and peroxisome proliferator-activated receptors (PPAR) genes expressions in blunt snout bream juveniles. Fish (average initial weight: 0.59 g) were fed diet supplemented with 0, 50, 100, 300 and 500 mg α-tocopherol acetate/kg in triplicates, which were found to, respectively, contain 11.2, 56.3, 114.6, 306.5 and 588.4 mg α-tocopherol/kg diet. Results showed that final weight, body weight gain and specific growth rate significantly increased with increasing dietary VE supplemented level from 11.2 to 56.3 mg/kg. When the broken-line model was employed to estimate the adequate requirement of vitamin E based on body weight gain, the optimal level was 55.5 mg/kg in diet. Hepatosomatic index value significantly decreased with incremental dietary VE levels. However, liver VE concentration showed a direct relationship with the dietary VE level. The percentages of 20:5n-3, 22:6n-3 and total n-3 long chain polyunsaturated fatty acids in liver increased with increasing dietary VE supplementation. Meanwhile, the expressions of PPAR-α, PPAR-β and PPAR-γ in liver were down-regulated by supplementation of dietary VE level from 56.3 to 588.4 mg/kg. In conclusion, supplementation of more than 55.5 mg/kg vitamin E may improve growth and increase n-3 LC-PUFA content in blunt snout bream, which is beneficial to human consumer.     

Effects of dietary fish oil substitution with mixed vegetable oils on growth and fillet fatty acid composition of juvenile Caspian great sturgeon (Huso huso)

The objective of this study was to determine the effects of fish oil replacement with dietary vegetable oils on growth performance, chemical composition and fatty acids profiles in fillets of farmed Caspian great sturgeon juveniles Huso huso (26.97 ± 0.49 g). Five isonitrogenous and isolipidic diets were formulated, containing 10 % of added oil. The diet with 100 % kilka fish oil (Caspian tyulka, Clupeonella caspia) was the control. Fish oil was substituted by 50 % of vegetable oils consisting of an equal share of sunflower and soybean oils (diet A), sunflower and canola oils (diet B) and soybean and canola oils (diet C). In diet D, 100 % of fish oil was replaced with vegetable oil (1:1:1 ratio of sunflower oil, soybean oil and canola oil). Significant differences (P > 0.05) were not detected during 60 days feeding trial in final body weight, weight gain, condition factor, specific growth rate, feed conversion rate, protein efficiency ratio and the chemical composition of fillet (crude protein, crude lipid, moisture and ash). Generally, the fatty acids composition of fish fillets was reflective of the dietary lipid sources. These results indicate the feasibility of substituting fish oils with the mixture of vegetable oils in diets of juvenile H. huso without negative influence on growth providing optimum ratios of n-3/n-6 and n-3/18:1n-9 is met in the diet.     

Hatchery broodstock conditioning of the blue mussel <Emphasis Type="Italic">Mytilus edulis</Emphasis> (Linnaeus, 1758). Part II. New formulated feeds offer new perspectives to commercial hatcheries

Five diets were compared for their efficiency at maturing the gonads of the blue mussel, Mytilus edulis. The diets consisted of a 1:1:1 mixture of Isochrysis galbana (T-Iso), Pavlova lutheri, and Chaetoceros calcitrans given at concentrations of 2.4 × 10¹¹ cells day^?1 for the positive control treatment (PF) and 3.0 × 10¹⁰ cells day^?1 (=1/8) for the negative control treatment (NF). The other three treatments, MB10+, MyStock+, and Frippak+, consisted of the NF diet supplemented with one of the micro-encapsulated diets MB10 (mixture of dried algae), MyStock (formulated diet), and FRiPPAK^® Fresh #1 CAR (larval shrimp diet) at a level of 0.2% of the live weight (LW). Treatments PF, MB10+, and MyStock+ led to high percentages of spawning animals (80, 78, and 85%, respectively) and large numbers of eggs (on average 3.0 × 10⁶ eggs female^?1). Females given the NF and Frippak+ treatments produced only half the number of eggs per female, and only 17 and 6%, respectively, of the animals spawned. A high hatching rate was observed for all treatments, 71% for the pure algae diets PF and NF and more than 80% for the micro-encapsulated diets. The larvae resulting from the NF treatment were smaller, with 41% of D-larvae measuring less than 90 μm, whereas with the other treatments only 5–11% belonged to that size category. The four most important fatty acids found in mussel eggs were 16:0, 16:1(n?7), eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA); these represented at least 50% of the fatty acids in all treatments. The high DHA content of MB10 and MyStock was not reflected in the fatty acid composition of the eggs whereas the high concentration of linoleic acid in MyStock was. To our knowledge, this is the first time that mussels are successfully conditioned with formulated feeds.     

Influence of nutrition on the lipid quality of pond fish: common carp (Cyprinus carpio) and tench (Tinca tinca)

Like marine fish freshwater fish are an important source of essential fatty acids for human nutrition. However, the fatty acid composition of pond fish can vary considerably and strongly depends on that of the ingested food. Investigations on the fatty acid composition of common carp (Cyprinus carpio) and tench (Tinca tinca) have shown that different methods of rearing and feeding cause substantial variations in the proportions of the n-6 and n-3 polyunsaturated fatty acids of these fish species. Carp reared on the basis of natural food in ponds exhibit high contents of n-6 as well as n-3 fatty acids in their muscle triacylglycerols. On the other hand carp fed supplementary wheat in ponds resulted in somewhat lower levels of these essential fatty acids. High amounts of n-3 fatty acids can be found in carp fed high-energy diets containing high levels of fish oil. Analogous results were obtained in experiments with tench reared under different nutritional conditions. While rearing on the basis of only natural food in ponds as well as feeding supplementary wheat yielded in similar levels of n-3 and n-6 polyunsaturated fatty acids, higher contents of n-3 fatty acids were recorded in tench fed pellets. High levels of n-3 polyunsaturated fatty acids in foodstuffs have positive effects on human health. Experiments with different cultured fish species proved that the fatty acid composition of the edible parts can be influenced by the diet. Therefore, a finishing diet with a suitable fatty acid profile can be used to improve the nutritional quality of fish products of farmed origin.     

Echium oil increased the expression of a Δ4 Fads2 fatty acyl desaturase and the deposition of n-3 long-chain polyunsaturated fatty acid in comparison with linseed oil in striped snakehead (<Emphasis Type="Italic">Channa striata</Emphasis>) muscle

Despite the potential of vegetable oils as aquafeed ingredients, a major drawback associated with their utilization is the inferior level of beneficial n-3 long-chain polyunsaturated fatty acids (LC-PUFA). Echium oil (EO), which is rich in stearidonic acid (SDA, 18:4n-3), could potentially improve the deposition of n-3 LC-PUFA as the biosynthesis of LC-PUFA is enhanced through bypassing the rate-limiting ?6 desaturation step. We report for the first time an attempt to investigate whether the presence of a desaturase (Fads2) capable of ?4 desaturation activities and an elongase (Elovl5) will leverage the provision of dietary SDA to produce a higher rate of LC-PUFA bioconversion. Experimental diets were designed containing fish oil (FO), EO or linseed oil (LO) (100FO, 100EO, 100LO), and diets which comprised equal mixtures of the designated oils (50EOFO and 50EOLO) were evaluated in a 12-week feeding trial involving striped snakeheads (Channa striata). There was no significant difference in growth and feed conversion efficiency. The hepatic fatty acid composition and higher expression of fads2 and elovl5 genes in fish fed EO-based diets indicate the utilization of dietary SDA for LC-PUFA biosynthesis. Collectively, this resulted in a higher deposition of muscle eicosapentaenoic acid (EPA, 20:5n-3) and docosahexaenoic acid (DHA, 22:6n-3) compared to LO-based diets. Dietary EO improved the ratio of n-3 LC-PUFA to n-6 LC-PUFA in fish muscle, which is desirable for human populations with excessive consumption of n-6 PUFA. This study validates the contribution of SDA in improving the content of n-3 LC-PUFA and the ratio of EPA to arachidonic acid (ARA, 20:4n-6) in a freshwater carnivorous species.     

Use of thraustochytrid <Emphasis Type="Italic">Schizochytrium</Emphasis> sp. as source of lipid and fatty acid in a formulated diet for abalone <Emphasis Type="Italic">Haliotis asinina</Emphasis> (Linnaeus) juveniles

The effects of using thraustochytrid Schizochytrium sp. as source of lipid and fatty acids in a formulated diet on growth, survival, body composition, and salinity tolerance of juvenile donkey’s ear abalone, Haliotis asinina, were investigated. Treatments consisted of diets either containing a 1:1 ratio of cod liver oil (CLO) and soybean oil (SBO) (Diet 1) or thraustochytrid (Diet 2) as source of lipid and fatty acids at 2 % level. Natural diet Gracilariopsis heteroclada (Diet 3) served as the control. No significant difference in growth was observed in abalone fed Diet 3 (SGR: 5.3 % BW day^?1; DISL: 265 μm day^?1) and Diet 2 (SGR: 5.2 % BW day^?1; DISL: 255 μm day^?1). Survival ranged from 78 to 85 % for all treatments and was not significantly different from each other. A 96-h salinity stress test showed highest survival of 84 % in abalone fed Diet 2 compared with those fed diets 1 and 3 (42 %). The high growth rate of abalone fed Diet 2 and high tolerance to low salinity could be attributed to its high DHA content (8.9 %), which resulted to its high DHA/EPA ratio of 10.5 %. These fatty acids play a significant role in abalone nutrition. The fatty acid profile of abalone meat is a reflective of the fatty acid profile of the oil sources in the diet. The present study suggests that the use of Schizochytrium oil in lieu of CLO and SBO can support good growth of abalone which is comparable with abalone fed the natural seaweeds diet.     

Quality of Filleted Atlantic Mackerel (Scomber Scombrus) During Chilled and Frozen Storage: Changes in Lipids,Vitamin D,Proteins, and Small Metabolites,including Biogenic Amines

Quality changes of vacuum-packed Atlantic mackerel (Scomber scombrus) fillets during 12 months’ frozen storage at ?27°C and 9 days’ chilled storage at +4°C were evaluated. Freezing at ?27°C preserved the long chain n-3 polyunsaturated fatty acids (LC n-3 PUFAs), both in light and dark muscle, vitamin D, and the low molecular weight metabolites (LMW) (studied by high resolution nuclear magnetic resonance spectroscopy, HR NMR). Protein oxidation took place, especially between 1 and 7 months, decreasing water holding capacity and protein extractability. During chilled storage, no lipid or protein oxidation was observed, but lipolysis increased, and several LMW metabolites relevant for sensory and nutritional quality degraded into non-favorable compounds. The content of biogenic amines was high at day 9 (e.g., 18 mg histamine/100 g), jeopardizing safety. Preservation of mackerel fillets by freezing at ?27°C is thus a better option compared to prolonged chilled storage at +4°C; the quality was well preserved for 12 months’ frozen storage.     

Growth performance and biochemical composition of juvenile pearl oyster <Emphasis Type="Italic">Pinctada martensii</Emphasis> fed on artificial diets

The effects of three artificial diets (S1, S2 and S3) on survival, growth and biochemical composition of one-year-old pearl oyster Pinctada martensii were investigated. Six experimental groups (EG1, EG2, EG3, EG4, EG5 and EG6) and one control group (CG) were set up. EG1, EG2 and EG3 were solely fed on S1, S2 and S3, respectively. EG4, EG5 and EG6 were fed on mixed diets, as follows: S1 and Platymonas subcordiformis; S2 and P. subcordiformis; and S3 and P. subcordiformis, respectively. CG was fed on only P. subcordiformis. All groups were continuously fed for 60 days. Survival, growth and biochemical composition of soft tissues were compared across the groups. Results showed that survival rate, the absolute growth rate (AGR) and relative growth rate (RGR) of shell length did not differ significantly across the groups (p > 0.05). The AGR and RGR of total weight differed significantly among the groups (p < 0.05). AGR and RGR of shell length and total weight were the highest in EG5 and the lowest in EG1. Gross fat content showed insignificant differences among the groups (p > 0.05). However, gross protein content and ash content showed significant differences across the groups (p < 0.05). The gross protein of the groups solely fed on artificial diets was lower than those of the groups fed on mixtures of artificial diets and microalgae or single microalgae. The contents of other amino acids, total amino acids (TAAs) and essential amino acids (EAAs) showed significant differences across the groups (p < 0.05). TAA, EAA and delicious amino acids of the groups fed solely on artificial diets were lower than those of the groups fed on mixtures of artificial diets and microalgae or single microalgae. Results indicated that the artificial diet (S2) can serve as substitutes of microalgal diets for P. martensii.     

Preservation Methods for Retaining N-3 Polyunsaturated Fatty Acids in Alaska Coho Salmon (Oncorhynchus kisutch) Products

Abstract

Coho salmon (Oncorhynchus kisutch) fillets were processed using five different methods (smoking, canning, freezing, acidifying, and salting) to evaluate the effect of preservation choice on the quality of polyunsaturated fatty acids (PUFA). Salmon preserved by smoking, canning, or freezing retained higher values of total fatty acids, including n-3 PUFAs such as eicosapentaenoic acid and docosahexaenoic acid. Salting and acidifying (pickling) treatments resulted in a significant decrease in PUFAs. The results of this study are intended to provide direction for handling and storage of salmon to retain the maximum levels of high-value n-3 PUFAs.     

Effect of dietary Spirulina platensis on fatty acid composition of rainbow trout (Oncorhynchus mykiss) fillet

This paper reports on inclusion of Spirulina platensis (SP) in rainbow trout (Oncorhynchus mykiss) fish diet and its effect on the fish tissue fatty acids (FAs) composition. Fish in triplicate groups with average initial body weight of 75 ± 0.23 g and age of about 7 months were fed a control diet with no supplements and with three experimental diets supplemented with 2.5, 5 and 7.5 weight percent (wt%) of SP for 12 weeks. At the end of experiment, the fillet FA compositions were evaluated. It was found that the composition of FAs in fish fillet was significantly (P < 0.05) affected by inclusion of SP in diets. As compared to the control sample, feeding the fish supplemented particularly with low levels of SP improved the quality of FAs by decreasing undesirable saturated FAs (SFAs) content from 20.03 to 17.93 % and increasing the level of some beneficial long-chain highly unsaturated FAs namely eicosapentaenoic acid (C20:5 n-3) from 6.47 to 7.27 %, docosapentaenoic acid (C22:5 n-3) from 1.42 to 1.56 % and docosahexaenoic acid (C22:6 n-3) from 1.26 to 1.35 %. Further increase in the SP inclusion level generally did not lead to desirable results. The SP inclusion in the fish diet had no significant impact on overall contents of n-3 and n-6 polyunsaturated FAs in fish fillet. However, the total highly unsaturated FAs (HUFAs) and n-3 HUFAs levels, UFAs/SFAs ratio and n-3/n-6 index were increased from 11.25, 10.65, 3.98 and 0.57 to 12.13, 11.56, 4.40 and 0.62 %, respectively, as a result of 5 wt% SP loading. In general, it can be concluded that SP inclusion up to 5 wt% of loading in rainbow trout culture can be beneficial in terms of FAs compositions of the fish fillet.     

Comparison of fatty acid and amino acid profiles of steamed Chinese mitten crab

The fatty acid and amino acid compositions of different grades of steamed Chinese mitten crab were analyzed. In total, 37 types of fatty acid were identified and quantified, with monounsaturated fatty acids and polyunsaturated fatty acids (PUFAs) constituting approximately 70 % of all fatty acids. Oleic acid, palmitic acid, and linoleic acid were dominant with approximately 30, 20, and 10 % of overall contents, respectively. The highest levels of fatty acids were found in special-grade animals, followed by first-grade and second-grade samples. The ratio of n-3/n-6 PUFAs ranged from 0.54 to 2.64, showing Eriocheir sinensis to be rich in n-3 PUFAs. In addition, claw and body meat were rich in amino acids and essential amino acids (EAA), while leg meat had higher content of flavor amino acids (FAA). Among almost all amino acids, the highest levels were found in Eriocheir sinensis of special grade, then first and second grade. On the whole, our results indicate that special-grade Eriocheir sinensis is highly nutritious due to its high levels of fatty acids and amino acids.