Factors that accelerate dimethylamine formation in dark muscle of three gadoid species during frozen storage

We investigated factors that accelerate dimethylamine formation in gadoid dark muscle. The degradation rate of trimethylamine-N-oxide into dimethylamine and formaldehyde during frozen storage was compared between ordinary muscle and dark muscle from walleye pollock, southern blue whiting, and hoki. Dimethylamine was generated faster in dark muscle than in ordinary muscle in each species, and it was produced most abundantly in hoki dark muscle compared with the other two species. We investigated the mechanism that caused dimethylamine to be generated more abundantly in dark muscle during frozen storage, and found that the amount of dark muscle nonheme iron, which catalyzes trimethylamine-N-oxide degradation, was higher than that in ordinary muscle in each species, and hoki dark muscle in particular contained the highest levels of nonheme iron among these three species. Moreover, dark muscle in all three fish species had a higher taurine content (known to accelerate dimethylamine formation) than ordinary muscle. These data suggested two candidate factors, namely nonheme iron and taurine, that may accelerate dimethylamine generation during frozen storage. In addition, gel filtration results suggested that walleye pollock dark muscle contains as yet unidentified low-molecular-weight agents that stably accelerate dimethylamine generation.     

Replacement of dietary fish oil with olive oil in young yellowtail <Emphasis Type="Italic">Seriola quingqueradiata</Emphasis>: effects on growth,muscular fatty acid composition and prevention of dark muscle discoloration during refrigerated storage

Dietary fish oil (FO) was replaced by olive oil (OO) in young yellowtail Seriola quinqueradiata to investigate its effects on growth, muscular fatty acid composition and prevention of color deterioration of dark muscle during storage. Yellowtail were fed one of four diets, where FO (80 g/kg diet) was replaced by OO (0, 25, 50 and 100%) for 40 days. No significant difference in growth was seen among the diet groups. In addition, these experimental diets did not affect the proximate compositions of the dorsal muscle, ventral muscle and the liver in these fish. Serum total protein, glucose and total cholesterol levels did not show significant differences; however, serum triglyceride levels were significantly higher in fish fed 50 and 100% OO diets. Fatty acid composition of ventral muscle reflected the composition of the respective diets. Dark muscle discoloration was reduced in fish fed OO diets after 12 to 18 h during storage at 4°C. Furthermore, the redness value of fresh dark muscle increased depending on the extent of FO replacement. These results indicate that the partial or total dietary replacement of FO with OO prevents discoloration of dark muscle without affecting the growth of young yellowtail after 40 days of feeding.     

Seasonal Changes in Proximate Composition and Fatty Acid Profile of Pufferfish (Lagocephalus sceleratus Gmelin, 1789) from the Mediterranean Sea of Turkey

This study represents a first report on the proximate composition and fatty acid profile of Lagocephalus sceleratus from the Mediterranean Sea as well as seasonal changes and sexual differences. Significant variations in the proximate composition were observed during the months of the study (p < 0.05). The highest moisture, fat, protein, and ash contents were found to be 78.47, 0.33, 21.62, and 1.63%, respectively. Total saturated and monounsaturated fatty acid values were similar throughout the year despite individual variations of 24.22–29.46 and 7.87–13.94%, respectively. However, significant variations were observed in total polyunsaturated fatty acids as well as significant differences between sexes (p < 0.05) with some exceptions. The major fatty acid was found as docosahexaenoic acid (DHA), between 24.17 and 32.65%. Due to the low fat content of this species, the highest eicosapentaenoic acid (EPA) + DHA values were calculated as 80.93 mg/100 g of edible muscle. The results indicated that this species contains high nutritional properties in terms of protein content and fatty acid values.     

Physicochemical Properties and Bioactivity of Extracts from the Roe of New Zealand Hoki and Southern Blue Whiting

ABSTRACT

Various physicochemical properties of New Zealand hoki and southern blue whiting (SBW) roes and the biological activities of their extracts were investigated. Protein, moisture, and ash contents in both roes were similar; however, the lipid content of hoki roe was higher (p < 0.05) than SBW roe (11.0 ± 0.9 and 2.5 ± 0.1, respectively). Both fish roe extracts contained active protease inhibitors toward trypsin and papain. Neither of the roe extracts agglutinated erythrocytes, indicating the absence of lectins. Both fish roe extracts at 5 mg/mL concentration exhibited slight inhibitory effects on the proliferation of breast cancer cells, but neither of the roe extracts exhibited RNase or antifungal activity.     

Variations in the proximate composition of muscle in cultured yellowtail Seriola quinqueradiata at different anatomical portions

In this study, we examined differences in the proximate composition of five major muscles of the yellowtail, as well as the relation between seasonal variations in the levels of crude lipids and texture of these muscles. The differences in content among these muscles and the variations in each muscle were greater for crude lipid and moisture content than for crude protein content. The crude lipid content of Musculus latero-dorsalis correlated with that of M. carinatus dorsalis, M. latero-ventralis, M. carinatus ventralis, and red muscle. In M. latero-dorsalis, the crude lipid content started to increase in October, remained high from November to January, started to decrease in March, and was low from April to June. The firmness of M. latero-dorsalis increased from October to November and started to decrease in March. Firmness decreased concurrently with decreases in crude lipid content and increased concurrently with increases in crude lipid content. The results of this study suggest that it is possible to predict the proximate compositions of other yellowtail muscles from the proximate composition of M. latero-dorsalis. Seasonal variation in crude lipid content of the M. latero-dorsalis was found, and variations in crude lipid tended to parallel those in firmness.     

Effect of Seasonality,Location, and Size on Lipid Content in North Pacific Troll-Caught Albacore Tuna (Thunnus alalunga)

ABSTRACT

Two hundred and thirty-nine albacore tuna (Thunnus alalunga) were troll-caught in the mid-Pacific Ocean and off the US Pacific Coast from June to November 2003. Catch location, harvest date, and sea surface temperature were recorded for individual fish, and lipid and moisture content in the white muscle were determined. The average weight of the alba-core was 6.07 kg and lipid content was highly variable (0.67–18.74%). There was an inverse correlation between the lipid and moisture content of albacore (R² = 0.93), and percent lipid increased slightly in fish caught later on in the season (R² = 0.24). Geographical Information Systems (GIS) software was used to determine correlations between lipid content and geographic location. Lipid content varied considerably among tuna caught at similar latitudes; however, most fish caught below 40°N had a lipid content of less than 10%, while the fish with the highest lipid content (13–19% lipid) were all harvested above 40°N.     

Seasonal Variations in Proximate and Fatty Acid Composition of Viscera of Sardinella aurita,Sarpa salpa,and Sepia officinalis from Tunisia

Seasonal variations of the proximate composition and fatty acid profiles in viscera from Sardinella aurita, Sarpa salpa, and Sepia officinalis were studied. Significant seasonal variations were observed in the amounts of moisture, lipid, protein, and ash between species. Viscera protein content undergoes large fluctuations. This tendency is different from results observed for the edible parts or for the whole body of many marine species. Ash content also showed significant differences. Lipid contents varied with seasons, in a proportionally inverse manner to water contents. Fatty acid composition showed significant differences from October to December. Interestingly, the highest total omega-3 contents were comparable to many commercial marine fish oils.     

Effects of Cooking Methods on Proximate Composition and Fatty Acids Profile of Indian White Prawn (Fenneropenaeus indicus)

The effects of baking, boiling, microwaving, and frying on the proximate composition and fatty acid content of the edible portion of Indian white prawns (Fenneropenaeus indicus) were determined. Mean moisture, lipid, protein, and ash contents of raw prawns were 72.1, 4.32, 21.5, and 1.31%, respectively. For all cooking methods, moisture decreased and protein increased, while fatty acid compositions changed uniquely for each method. In fried prawns, the n3/n6 ratio was the lowest and significantly differed from the other treatments. The heat treatment significantly changed the proximate composition and fatty acid content. Baking and microwaving are the best methods of the four for cooking prawn while preserving their nutritional value, especially on the basis of recommended dietary intake of DHA and EPA.     

Replacing dietary fish oil with increasing levels of rapeseed oil and olive oil – effects on Atlantic salmon (Salmo salar L.) tissue and lipoprotein lipid composition and lipogenic enzyme activities

Six groups of Atlantic salmon, initial weight 142 ± 1 g, were fed increasing dietary inclusion of rapeseed oil (RO) in a regression design and one group was fed a 50% olive oil/50% capelin oil diet. Fatty acid composition was measured in red and white muscle, liver, and fatty acid and lipid class composition was measured in plasma and in the lipoproteins; very low density lipoprotein, low density lipoprotein, high density lipoprotein and nonlipoprotein fraction after 22 and 42 weeks of feeding. Further, the activities of liver NADH‐isocitrate dehydrogenase (ICDH), malic enzyme, glucose‐6‐phosphate dehydrogenase (G6PDH) and 6‐phosphogluconate dehydrogenase were measured at each sampling point. After 42 weeks of feeding the experimental diets, the tissue and lipoprotein fatty acid composition was highly affected by dietary fatty acid composition. Regressions showed that 22:1n ? 11, 18:1n ? 9, 18:3n ? 3 and 18:2n ? 6 are readily metabolized in all tissues analysed. Further, 20:5n ? 3 seems to be metabolized in muscle and retained in liver. 22:6n ? 3 was selectively retained in all the analysed tissues, and with higher retention in liver and plasma with higher polar lipid/neutral lipid ratio compared to white and red muscle. Liver from salmon fed 100% RO showed decreased G6PDH and increased ICDH activities compared to the other dietary groups; however, no linear relationship related to increased RO inclusion was detected. The amount of plasma lipoproteins, liver monoene fatty acid level and lipogenic enzyme activity decreased from the autumn to the winter sampling with concomitant decrease in temperature.     

The Variations in Proximate Chemical Composition and Fatty Acid Profile in Different Parts of the Thornback Ray (Raja clavata) Caught from Black Sea,Turkey

Proximate chemical composition and fatty acid (FA) profile of different parts and sexes of ray (Raja clavata) were compared. The proximate values of liver samples significantly differed from other body parts (p < 0.05). Pectoral fin had the highest moisture, protein, and ash contents (78.6, 20.5, and 1.2%, respectively). The highest fat content (39.7%) was observed for liver samples. A significant variation was also observed between sexes in terms of proximate and FA values (p < 0.05). The levels of saturated (SFA), monounsaturated (MUFA), and polyunsaturated fatty acids (PUFA) varied between 27.1–32.1, 14.9–19.0, and 34.3–39.5%, respectively, in total fatty acid methyl esters (FAME). The highest total PUFA and docosahexaenoic acid (DHA) values were observed in the edible portion of liver for both sexes due to high contents of fat, despite the low values of % total FAME in comparison with other body parts. Significant variations among FA levels were observed for different body parts (p < 0.05). The highest DHA and eicosapentaenoic acid (EPA) values were found in the edible portion of the liver and calculated as 6.8 and 2.3 g/100 g, respectively, indicating the importance of utilizing the liver of this species.     

Effects of dietary lipids on the fatty acid composition of triglycerides and phospholipids in tissues of white sturgeon

Eight purified diets were fed to juvenile white sturgeon, Acipenser transmontanus Rick, for 9 weeks to investigate the effect of dietary lipids on the fatty acid composition of phospholipids and triglycerides from muscle, liver and brain. The diets contained 150 g kg^?1 of oils from canola, corn, cod liver, lard, linseed, soybean, safflower, or a control mixture (corn oil/cod liver oil/lard, 1:1:1, by wt). Dietary lipids significantly (P≤ 05) affected the composition of tissue triglycerides and phospholipids. Tissue triglyceride fatty acid composition ranged widely, in parallel with the dietary lipids, while phospholipids changes were more conservative. Brain phospholipid fatty acid composition was less responsive to diet compared with that in muscle and liver. Considerable amounts of n-6 and n-3 long chain polyun-saturated fatty acids (> C₂₀) were found in triglycerides and phospholipids with all diets, demonstrating that white sturgeon can desaturate and elongate linoleic acid (18:2n–6) and linolenic acid (18:3n–3). Further, the products of the Δ6 desaturase, i.e. 18:3 n–6 and 18:4n–3, were relatively abundant in triglyceride, suggesting that the Δ6 desaturase might not be a limiting step in the process in white sturgeon. Nevertheless, accumulation of both EPA and DHA was greater in the sturgeon fed fish oil than those fed linseed oil, indicating that muscle triglyceride EPA and DHA levels are best enhanced by diets rich in preformed EPA and DHA.     

Comparative study on nutrient composition and quality evaluation in a new variety and wild‐typed ridgetail white prawn (Exopalaemon carinicauda)

Kesuhong No. 1 with high concentration of astaxanthin was a newly approved aquaculture variety of ridgetail white prawn (Exopalaemon carinicauda) in China, and the information on the nutrient composition and quality evaluation of this new variety is insufficient. Thus, the proximate composition, amino acid and fatty acid profiles were analysed and compared between the new variety and the wild‐typed prawn in the present study, for its better application of the new variety. It showed that there were no significant differences (p > 0.05) of the proximate composition, essential amino acid and saturated fatty acid (SFA) of muscle tissue between the wild‐typed prawn and the new variety. However, for the content of some delicious amino acids (Ala and Tyr), it was significantly higher (p < 0.05) than that in the wild‐typed prawn. Similarly, for some ω3 polyunsaturated fatty acids (ω3 PUFA), such as docosahexaenoic acid (DHA) and eicosapntemacnioc acid (EPA), it was also significantly higher (p < 0.05) than that in the wild‐typed prawn. In addition, higher PUFA/SFA ratio and lower ω6/ω3 ratio also improved muscle quality in the new variety. Information obtained in the present study indicates a promising natural source of ω3 PUFA with high nutritional value, and has strong potential application value in this new variety of E. carinicauda.     

Effects of dietary fish oil replacement on growth and carcass proximate composition of juvenile barramundi (Lates calcarifer)

An experiment was carried out to determine the effects of dietary fish oil replacement at an optimal level on the growth and carcass proximate composition of juvenile barramundi or sea bass (Lates calcarifer). Ten fish feeds were formulated to contain iso‐ingredients with theoretically identical dietary lipid levels but with different sources of lipids (fish oil, soybean oil, canola oil and linseed oil) replacing dietary fish oil. Three hundred fish were equally divided into 30 70‐L plastic tanks (three replicate tanks for each treatment). Fish were fed with experimental diets for 40 days within closed recirculating freshwater systems (70 L h^?1, 28°C and 12L:12D). Growth, specific growth rate, food conversion ratio (FCR) and carcass proximate composition were determined. Dietary lipids significantly affected (P<0.05) the growth of the fish. Good growth and low FCR were observed in all treatments. Therefore, fish oils can be partially replaced by vegetable oils to reduce the feed cost. There were no significant differences (P>0.05) in lipid, moisture and protein content in fish carcasses among the group. However, juvenile barramundi showed increasing lipid and moisture content in muscle, whereas decreasing protein content when compared to the initial fish.     

Effects of Heat Treatment on the Antigenicity and Allergenicity of Grass Carp Muscles

ABSTRACT

Fish is one of the most common sources of food allergens, and grass carp is among the most popular freshwater fish. The objective of this study was to investigate the effects of heat treatment on the antigenicity and allergenicity of white and dark muscle of grass carp. The results showed that the antigenicity of heated white muscle was higher than that of unheated white muscle, while the allergenicity of white muscle was lower than that of unheated muscle when heated at 65°C, and the lowest value was 44.6%. Furthermore, the allergenicity of dark muscle increased for the first 30 min when heated at 65°C, and it increased for the first 60 min and then decreased with the increasing heating time thereafter when heated at 80 and 100°C. In addition, the lowest antigenicity and allergenicity of dark muscle were obtained at 100°C, and the values were 0.447 mg mL^?1 and 47.0%, respectively. Thus, to decrease the antigenicity and allergenicity of grass carp muscles, it is suggested that heating at 65°C is better than 80 or 100°C for the white muscle, while 100°C is an appropriate heating temperature for the dark muscle.     

三种水族馆珍贵鱼类的营养成分分析及脂肪酸营养评价

睛斑鳗狼鱼、巨巴西骨舌鱼和锥齿鲨是水族馆中珍贵的展示鱼类,但是有关这3种鱼类成体的营养生理研究却十分缺乏。本研究对从水族馆获得的成年睛斑鳗狼鱼、巨巴西骨舌鱼和锥齿鲨的肌肉和肝脏组织进行了常规营养成分(水分、灰分、粗蛋白和粗脂肪含量)和脂肪酸组成测定分析,并进一步将3种鱼类所食饵料与其肝脏和肌肉中的脂肪酸相对含量进行了比较。结果显示,在3种鱼中,锥齿鲨肌肉和肝脏中的蛋白质含量最高,分别为26.84%和24.03%;睛斑鳗狼鱼的肌肉和肝脏中的脂肪含量最高,分别为41.96%和32.27%;巨巴西骨舌鱼的肌肉和肝脏中的灰分含量最高,分别为4.95%和5.51%。锥齿鲨肌肉和肝脏中饱和脂肪酸(SFA)含量高于睛斑鳗狼鱼,睛斑鳗狼鱼肌肉和肝脏中单不饱和脂肪酸(MUFA)含量高于巨巴西骨舌鱼和锥齿鲨,巨巴西骨舌鱼肌肉和肝脏中多不饱和脂肪酸(PUFA)含量及其肌肉中UFA/SFA值高于睛斑鳗狼鱼和锥齿鲨。研究表明,锥齿鲨所食饵料与其体内脂肪酸组成最为相似,其肌肉和肝脏与饵料的相关系数分别为0.972和0.861,其次是巨巴西骨舌鱼(0.912和0.846),而睛斑鳗狼鱼肌肉和肝脏中脂肪酸组成与所食饵料的相关系数仅分别为0.760和0.681。从脂肪酸营养的角度分析,在当前水族馆养殖条件下,锥齿鲨饵料较为合适,巨巴西骨舌鱼的饵料中应注意添加EPA和DHA,而睛斑鳗狼鱼饵料中则需提高MUFA比例。本研究首次阐明了3种珍贵的水族馆鱼类成体的营养组成,并为水族馆相应的饲料配制提供了重要的参考依据。     

Influence of dietary protein levels on growth performance, carcass composition and liver lipid classes of juvenile Spinibarbus hollandi (Oshima)

A feeding trial was conducted to investigate the influence of dietary protein levels on growth performance, carcass proximate composition and liver lipid classes of juvenile Spinibarbus hollandi (Oshima), a cyprinid fish. White fish meal was the primary protein source in the study. Eight experimental diets containing 13–55% crude protein were fed to three replicate groups of six fish weighing nearly 8.5 g each for 10 weeks. Both percentage weight gain and feed efficiency ratio increased significantly with increasing dietary protein levels up to 31%, but there was no further increase for protein levels from 31% to 55%. Application of broken‐line regression analysis to the percentage weight gain provided an estimate of 32.7±1.5% dietary protein for maximum growth. The protein efficiency ratio and productive lipid value were inversely correlated with dietary protein level. The hepatosomatic index and the viscerosomatic index were also inversely related to dietary protein level. The carcass protein of fish fed lower protein diets was significantly lower than that of the fish fed higher protein diets. Carcass lipid content decreased with increasing dietary protein levels, whereas moisture was inversely related to lipid content. Both liver glycogen and liver lipid contents decreased with increasing dietary protein levels. Triglyceride was the major component in the liver lipid, and the amount of triglyceride deposited in the liver also decreased with dietary protein levels. The results indicated that both carcass proximate composition and liver lipid class of juvenile Spinibarbus hollandi were affected by dietary treatments.     

The Influence of Different Dietary Carbohydrate to Lipid Ratios on Some Qualitative Characteristics of Fillets of Beluga (Huso huso) During Refrigeration

In this study, juvenile beluga (Huso huso) were fed diets containing different carbohydrate to lipid ratios for 5 months. At the end of the culture period, proximate compositions of the fish carcasses (moisture, protein, fat, and ash) were measured. Then, qualitative changes in the fishes were evaluated during 24-days refrigeration (4°C), along with changes in their total volatile bases nitrogen (TVN), thiobarbituric acid (TBA), free fatty acids (FFA), pH, and muscle texture profile analysis. The results of proximate analysis of the carcasses showed that moisture, protein, and ash of the carcasses increased significantly (p < 0.05) with higher carbohydrate to lipid ratio, but fat content of the carcasses decreased significantly (p < 0.05). Further, during refrigeration, TVN, TBA, and FFA increased significantly in all the samples (p < 0.05), but these changes did not follow the same pattern in all the treatments. Tissue hardness decreased during preservation. Although pH changes in the fillets were low, they were significant and without a clear-cut pattern. The results showed that use of different carbohydrate to lipid ratios in diet does not lead to clear-cut changes in qualitative characteristics of beluga fillets during refrigeration.     

Effects of dietary thyroid hormones on the red drum (Sciaenops ocellatus)

Four separate 8-week feeding trials were conducted to assess the effects of supplementing semipurified diets with either triiodothyronine (T₃) or thyroxine (T₄) at 0, 2, 10, and 50 mg/kg on growth and body composition of juvenile red drum (Sciaenops ocellatus) held in artificial brackish water (6‰) and artificial seawater (32‰). At both levels of salinity, increasing doses of T₃ resulted in fish with reduced weight gain, feed efficiency, condition factor (weight × 100/length³), and muscle ratio (muscle weight × 100/body weight), as well as a lighter body color. Significant (p < 0.05) effects of T₃ on the proximate composition of whole body, liver, and muscle were variable, generally reflecting decreased lipid and protein storage in liver and muscle, respectively. The two highest doses of T₃ given to seawater adapted fish increased survival. Dietary T₄ supplementation had no distinctive effects on appearance, growth or proximate body composition. These results indicate that whereas T₃ may function to regulate protein and lipid metabolism in red drum, dietary supplementation with T₃ leads to a hyperthyroidism-induced catabolic state. The elevated endogenous thyroid hormone levels found in fish fed optimal diets may thus adequately supply tissue needs during juvenile growth.     

Exposure to seawater stimulates lipid mobilization from depot tissues of juvenile coho (Oncorhynchus kisutch) and chinook (O. tshawytscha) salmon

Tissue lipid content and lipolytic enzyme activity was determined in selected tissues of coho salmon,Oncorhynchus kisutch, at various developmental stages (freshwater parr, freshwater smolt, seawater smolt, and seawater stunt) and in tissues of coho salmon and chinook salmon,O. tshawytscha, exposed to seawater periodically during smoltification. Among developmental groups, total lipid concentration of liver and dark muscle was highest in freshwater (FW) parr. Lipid concentration in both liver and dark muscle was significantly lower in FW smolts, seawater (SW) smolts and SW stunts; no difference was observed among these groups. Alterations in lipid composition were reflected in depot triacylglycerol lipase activity. FW smolts, SW smolts and SW stunts displayed significantly higher lipase activity than FW parr in each of the tissues examined (live, dark muscle and mesenteric fat). Early in smoltification (March, April), exposure to seawater results in enhanced lipid depletion from liver, dark muscle and mesenteric fat, both 30 and 60 days after exposure, compared to FW controls. This depletion was accompanied by increased liver (March and April) dark muscle (March) and mesenteric fat (March) lipase activity. Later in smoltification (May), salinity-induced alterations in lipid metabolism were not observed. These results indicate that exposure to seawater stimulates lipid depletion in juvenile salmon and that the depletion can be explained, in part, by increased depot lipase activity. Furthermore, these data confirm that metabolic dysfunction is associated with stunting.     

Blue tilapia Oreochromis aureus (Steindachner) carcass composition and haematology in relation to the female parent size under recirculated water conditions

The relation between female parent size/age of Oreochromis aureus (Steindachner) and their offspring carcass composition and some haematological parameters was investigated. Blood parameters (glucose, triglycerides, albumin, cholesterol, total lipid, haematocrit, osmolarity), proximate carcass composition (crude protein, crude fat, moisture, ash), and total lipid content of liver were evaluated. No clear differences between populations could be reported regarding carcass composition. However, the offspring of the smallest/youngest female parent gave the highest crude protein and the lowest crude fat levels, while that of the largest/old female parent showed an opposite picture. Results obtained on blood parameters and liver lipid content were not clearly related to the female parent size/age, nor to the final body weight of the populations, despite the statistically significant (P < 0.05) differences observed for glucose, triglycerides and plasma and liver total lipids. It is concluded that more research is needed in order that a clear correlation between the female parent size/age and the investigated biochemical parameters of their progeny to be established.