Preparation of Chitosan/Rosemary Extract Nanoparticles and their Application for Inhibiting Lipid Oxidation in Grass Carp (Ctenopharyngodon idellus) during Cold Storage

This study investigated a preparation of chitosan/rosemary extract nanoparticles (CS/RE-NPs) based on the principle of ionic gelation and their application for inhibiting grass carp lipid oxidation. CS/RE-NPs were found to have a rosemary extract (RE) encapsulation efficacy of 40.33%, average particle size of 199.90 nm, and zeta-potential of 35.60 mV. Structural analysis using UV–vis spectroscopy, Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), and transmission electron microscopy (TEM) indicated that the RE s were well incorporated into the CS-NPs. Treatment of the CS/RE-NPs inhibited lipid oxidation of the grass carp during cold storage, and the peroxide value (PV), thiobarbituric acid-reactive substance (TBARS) value, and lipoxygenase (LOX) activity of the CS/RE-NP-treated samples were lower than those of RE and CS-NP-treated samples, respectively. CS/RE-NP-treated samples also slowed the growth of bacteria, enhanced the organoleptic quality, and prolonged the shelf life of grass carp. This study suggested that CS/RE-NPs can be used as an antioxidant delivery system to inhibit lipid oxidation and improve food quality.     

Influence of Dietary Lipid and Protein Sources on the Sensory Quality of Organic Rainbow Trout (Oncorhynchus mykiss) After Ice Storage

The influence of dietary protein and lipid sources on the quality of organic rainbow trout (Oncorhynchus mykiss) was studied. The protein and oil sources were fishmeal, fish oil, and organic vegetable protein and oils. Sensory profiling was performed during 3 to 14 days of ice storage along with lipid analyses of the fillet. Overall, the results showed that the sensory characteristics of the trout were affected in different ways during ice storage. The source of lipid seemed to affect the sensory quality at the beginning of the storage period, while the protein source seemed to have a more pronounced impact at the end of the storage period.     

Lipid Oxidation and Omega-3 Fatty Acid Retention in Salmon and Mackerel Nuggets During Frozen Storage

The extent of lipid oxidation and retention of omega (ω)-3 fatty acids in milk protein concentrate (MPC)-added mackerel and salmon mince and nuggets during 4-months frozen storage were investigated in order to develop high ω-3 seafood products. Mechanically deboned fish mince formulated with MPC and other ingredients was formed into batter-breaded nuggets with or without par-frying. The addition of MPC at 4% resulted in significantly lower thiobarbituric acid reactive substances (TBARS) values and helped retain significantly (p < 0.05) higher amounts of docosahexaenoic acid (DHA) in both salmon and mackerel mince and eicosapentaenoic acid (EPA) in the mackerel mince. There were no significant differences in peroxide values (PV) and TBARS values between nugget products with and without par-frying. EPA and DHA were retained less in par-fried than raw nuggets probably due to oil leaching and thermal degradation during frying. The reductions of EPA and DHA in salmon were 67% and 53% for raw and 57% and 39% for par-fried nuggets, while in mackerel they were 63% and 73% for raw and 57% and 56% for par-fried nuggets, respectively. Results suggest that although MPC provided some protection against lipid oxidation, additional measures are needed to improve retention of ω-3 fatty acids in mince-based seafood products during frozen storage.     

Changes in Protein Oxidation,Water-Holding Capacity,and Texture of Bighead Carp (Aristichthys Nobilis) Fillets Under Chilled and Partial Frozen Storage

This study aimed to evaluate the contribution of protein oxidation to the changes in the water-holding capacity (WHC) and texture of bighead carp (Aristichthys nobilis) fillets under chilled and partial frozen storage (4°C and ?3°C). The results indicated that less protein oxidation occurred to fillets at ?3°C than at 4°C, which was reflected by the higher value of salt-soluble protein contents (SSP), total sulfhydryl content (SH), Ca²⁺-ATPase activity, lower water-soluble protein contents (WSP), total disulfide content (SS), and surface hydrophobicity (So-ANS). However, the fillets had better WHC and texture at 4°C, as well as lower drip loss and higher centrifugal loss, hardness, and springiness. A significant linear relationship existed between protein oxidation parameters with WHC and texture characteristics for fillets under both types of storage, but the process of freezing and then thawing, instead of protein oxidation, was the main factor affecting the texture and WHC of fillets at ?3°C.     

Lipolysis and Lipid Oxidation during Processing of Chinese Traditional Dry-Cured White Amur Bream (Parabramis pekinensis)

Lipolysis and lipid oxidation of intramuscular lipids during the dry-curing process of white amur bream (Parabramis pekinensis) were studied. All lipolytic enzyme activities decreased (p < 0.05) at the end of the process. The lipoxygenase activity increased during wet-salting (p < 0.05) and then decreased until the end of the process (p < 0.05). The daily variation of free fatty acids was correlated with those of the peroxide value (r = 0.976, p < 0.01) and thiobarbituric acid-reactive substances (r = 0.922, p < 0.01), respectively. These results suggest that lipolysis promotes lipid oxidation during the processing of dry-cured fish.     

Influence of Varying Dietary Protein Content at Three Lipid Concentrations on Growth Characteristics of Juvenile Swordtails (Xiphophorus helleri Heckel 1848)

Three protein levels (30%, 38% and 45%) at three different dietary lipid concentrations (6%, 8% and 12%) were used to formulate nine different diets that were fed for 60 days to 6–8 weeks old juvenile swordtails (Xiphophorus helleri). It would appear that a diet of at least 45% protein at a 6% lipid concentration is needed for the best specific growth rate (1.27% per day) and feed conversion ratio (2.50) at this specific growth phase in X. helleri. No ‘protein sparing effect’ was found when lipid concentration was increased at lower protein levels. This revised version was published online in August 2006 with corrections to the Cover Date.     

Lipid Hydrolysis and Oxidation of Mackerel (Scomber scombrus) Mince

Atlantic mackerel was stored at refrigeration or frozen temperatures under vacuum or in air with various treatments to determine lipid hydrolysis and oxidation in the fish muscle. Lipid oxidation in the fish minces occurred continually as long as the samples were exposed to air independent of hydrolytic activity which was deactivated or retarded by cooking the sample or by lowering the storage temperature (-40°C). Lipid oxidation was observed not only in the free fatty acids, but also in the triacylglycerides and the phospholipids extracted from mackerel mince.     

Protein and Energy Levels for Maximum Growth, Diet Utilization, Yield of Edible Flesh and Protein Sparing of Hybrid Clarias Catfish (Clarias macrocephalus×Clarias gariepinus)

Abstract— Two feeding trials were performed to determine dietary protein and energy levels for maximum growth, diet utilization, yield of edible flesh and protein sparing of hybrid Clarias catfish ( Clanas macrocephalus × Clarias gariepinus ). A 3 × 3 factorial design was employed for experiment 1 in which nine diets containing either 20, 30 or 40% protein and 275, 300 or 325-kcal digestible energy/100 g were used. The follow-up experiment 2 was a 3 × 2 factorial in which three protein levels (30, 35 and 40%) and two digestible energy levels (275 and 325 kcal/100 g) were tested. Dietary ingredients used in both studies were similar but the ratios of energy provided by dextrin and lard were 11.3/1.0 and 3.8/1.0 for experiments 1 and 2, respectively. Each of the experimental diets was fed to apparent satiation twice daily to three aquaria of fish (15 fish/aquaria) with average weight of 4.0 and 2.0 g for experiment 1 and 2, respectively, for 8 wk. Performance of fish in experiment 1 was mainly influenced by dietary protein rather than by energy levels. Maximum growth and diet utilization were attained at dietary protein and energy levels of 40% and 275 kcal/100 g, respectively. Energy levels did not spare dietary protein in experiment 1. In experiment 2, growth, diet utilization, and yield of edible flesh of fish were influenced by protein and energy levels. Furthermore, the protein sparing effect was observed in experiment 2. Best performance and protein sparing were found at 35% protein and 325-kcal digestible energy/100 g. The studies showed that dietary protein and energy requirement for hybrid Clarias catfish are affected by carbohydrate to lipid ratio. Fish utilize dietary energy with a dextrin to lard ratio of 3.8/1.0 more efficiently than that with a ratio of 11.3/1.0. Therefore, dietary protein and energy for best performance and protein sparing of hybrid Clarias catfish reported for experiment 2 were more appropriate.     

Study on Gel Properties of Silver Carp (Hypophthalmichthys molitrix) and White Croaker (Argyrosomus argentatus) Blended Surimi at Different Setting Conditions

Gel properties of blends of surimi from silver carp and white croaker set for a range of times and at different temperatures were evaluated for breaking force, breaking distance, and whiteness. Total protein content was 12% in all samples, and the concentration of white croaker surimi protein in the blends was designed at 0, 10, 20, 30, and 40%. The blended surimi had greater gel strength than either of the two types of surimi alone. Breaking force and breaking distance after setting were also significantly higher than that of the blended surimi cooked directly without setting. The blended surimi exhibited less modori than either of the two types of surimi alone heated to 50°C. The whiteness values of the blended surimi were significantly higher than that of white croaker alone. These results indicate there are advantages to be gained in utilizing surimi from freshwater silver carp in blends with surimi from marine captured white croaker which is becoming limited in supply.     

Effect of Squid Melanin-Free Ink and Pre-Emulsification on Properties and Stability of Surimi Gel Fortified with Seabass Oil during Refrigerated Storage

ABSTRACT

The effects of melanin-free ink (MFI) and pre-emulsification on gel properties and stability of bigeye snapper surimi gel fortified with seabass oil during refrigerated storage of 10 days were studied. Lipid oxidation as determined by peroxide value (PV) and thiobarbituric acid reactive substances (TBARS) of surimi gel increased as the level of seabass oil increased (P < 0.05). When MFI was incorporated into surimi gel, lower PV was obtained throughout the storage (P < 0.05). Addition of seabass oil pre-emulsified with soy protein isolate (SPI) in the presence of MFI yielded surimi gel with the highest breaking force and could improve oxidative stability during refrigerated storage (P < 0.05). Slight decrease in whiteness was found in surimi gel added with MFI, while those added with MFI along with pre-emulsified seabass oil showed increased whiteness (P < 0.05). Addition of MFI did not affect total viable count and psychrophilic bacterial count in surimi gels. Thus, the incorporation of pre-emulsified seabass oil prepared using SPI in conjunction with MFI could improve quality and oxidative stability of gel from bigeye snapper surimi.     

Gel Properties of Surimi from Silver Carp (Hypophthalmichthys molitrix): Effects of Whey Protein Concentrate,CaCl2, and Setting Condition

The effects of setting time, whey protein concentrate (WPC), and calcium chloride (CaCl₂) on textural properties of silver carp surimi were investigated. Response surface methodology was used to evaluate and compare the effects of setting time (30–90 min), WPC (1–9% of protein ratio), and CaCl₂ (1–59 mmol/kg) on the gel strength. Models for breaking force, breaking distance, and gel strength of surimi gel were established. The maximum gel strength was achieved at the setting time of 60 min, WPC and CaCl₂ at 5% protein ratio, and 15–18 mmol/kg. CaCl₂ was the most significant factor affecting the gel strength.     

软颗粒饲料与鲜杂鱼糜对大黄鱼养殖水质的影响

在水温18．0～21．0℃、盐度21．0～25．8下,给平均体质量为280．0 g／尾的大黄鱼投喂软颗粒饲料（试验组）和鲜杂鱼糜（对照组）,评价两种饲料对环境影响,其中试验组、对照组各设3个平行,空白组（不放鱼也不投料,仅有砂滤海水）不设平行。试验结果表明,试验组和对照组养殖水中总氮、总磷和化学需氧量含量均与空白组差异显著（P＜0．05）,对照组最高,空白组最低;试验组与对照组水中总磷差异不显著（P＞0．05）,而总氮和化学需氧量含量均差异显著（P＜0．05）;试验组水中沉积物总量显著少于对照组（P＜0．05）;试验组水中沉积物中总氮、总磷总量均显著少于对照组（P＜0．05）。软颗粒饲料对养殖环境的影响显著小于鲜杂鱼糜,可在海水鱼类网箱养殖中应用推广。     

Growth,Feed Conversion,and Nutrient Retention Efficiency of African Catfish,Clarias gariepinus, (Burchell) Fingerling Fed Diets with Varying Levels of Protein

Growth, feed conversion, and nutrient retention efficiencies of African catfish fingerling, Clarias gariepinus (5.22 ± .07 cm; 8.22 ± 0.03 g), fed diets with varying levels of protein were assessed by feeding seven casein/gelatin based isocaloric (17.62 kJ/g GE) experimental diets with graded levels of dietary protein (20%, 25%, 30%, 35%, 40%, 45%, and 50% of the diet) to triplicate groups of fish to apparent satiation for eight weeks. Effects of feeding these diets on live weight gain (LWG%), feed conversion ratio (FCR), protein efficiency ratio (PER), protein retention efficiency (PRE%), and energy retention efficiency (ERE%) were assessed. Maximum LWG% (867%), PER (2.01), highest PRE (32%), ERE (69%), best FCR (1.39), and maximum body protein were recorded in fish fed diet containing 35% protein. On the basis of the second-degree polynomial regression analysis of the above response variables, it is recommended that the inclusion of protein in the range of 34.4%–39.6% is optimum for maximizing growth potential, feed conversion, and nutrient retention in African catfish fingerling, Clarias gariepinus.     

Stability of Fish Powder Made from Saithe (Pollachius virens) as Measured by Lipid Oxidation and Functional Properties

ABSTRACT

Lipid oxidation and functional properties were monitored in spray dried fish powder made from saithe (Pollachius virens) by-products. The fresh powder exhibited slight antioxidant activity in a model system of linoleic acid emulsion. The freshly made powder had low lipid extract-ability in polar solvents and over 30% free fatty acids (FFA). Further lipid oxidation took place during storage, independent of storage temperatures. Functional properties measured by color changes, water-binding capacity, apparent viscosity and protein solubilty changed more during storage at 30°C than 0°C.     

Storage of lipids in the myosepta of Atlantic salmon (Salmo salar)

Storage of lipids in the myosepta of Atlantic salmon (Salmo salar) was determined by dissection of myosepta from both white and dark muscle, by analyzing lipid classes of myosepta, and by analysis of muscle tissues with and without myosepta. By using Iatroscan-TLC/FID it was found that triglyceride was the only major lipid class present in the myosepta. In a sample pooled from three fish, 39.1% of white muscle lipids were found to be stored in the associated myosepta. In the dark muscle up to 62.4% of the total lipids were located in the associated myosepta.After removal of the myosepta, the ratio of the total lipid content of dark muscle to white muscle decreased from 5.25 to 3.66. The proportion of polar lipids increased in both white muscle and dark muscle after removal of the myosepta; however the ratio of phosphatidyl choline (PC) to phosphatidyl ethanolamine (PE) in both muscle types remained constant. This suggests that neutral lipids accounted for most of the lipids in the myosepta. It is concluded that this type of connective tissue, not the actual muscle fibres, stores most of the muscle lipids in Atlantic salmon.     

黄颡鱼幼鱼对蛋白质和脂肪的需要量

在水温23±5℃下,将平均体质量10．32g的黄颡鱼（Pelteobagrus fulvidraco）放养在27个60cm×60cm×120cm的微流水网箱中,饲喂3个蛋白质水平（32．0％、40．0％、48．0％）,每个蛋白质水平设3个脂肪水平（3．0％、10．0％和17．0％）的饲料,饲养100d。结果表明：在3．0％脂肪水平下,黄颡鱼摄食含40．0％蛋白质的饲料时,平均末体质量、特定生长率和蛋白质效率显著提高,饲料系数降低（P〈0．05）。在10．0％脂肪水平下,黄颡鱼摄食含48．0％蛋白质饲料时,饲料系数显著降低（P〈0．05）,摄食含40．0％的蛋白质饲料次之。黄颡鱼摄食含48．0％蛋白质与3．0％脂肪饲料组和40．0％蛋白质与10．0％脂肪组的干物质消化率最高（P〈0．01）;蛋白质消化率在48．0％蛋白质与3．0％脂肪达到最高（P〈0．01）,脂肪消化率均在40．0％蛋白质与10．0％脂肪达到最高（P〈0．01）。实验表明,黄颡鱼幼鱼较为适宜的蛋白质和脂肪需要量分别为40．0％和10．0％。     

Effects of dietary nano and macro iron oxide (Fe2O3) on the growth,biochemical, and hematological profiles of African catfish (Clarias gariepinus) fingerlings

Effects of nano and macro iron oxide as dietary iron sources on the growth, hematological, and biochemical characteristics of African catfish, Clarias gariepinus, fingerlings have been studied. Conventional basal feed was supplemented with nFe₂O₃ and Fe₂O₃ as treatments T₁ and T₂ (each at 0.0, 0.2, 0.4, 0.8, 1.2, and 1.6 g/kg supplementation levels) and given to C. gariepinus fingerlings (initial average weight and length 5.01 ± 0.80 g and 7.0 ± 0.53 cm respectively) for 7 weeks. After 7 weeks, the highest percent weight gains of 395.6% for T₁ and 767.4% for T₂ occurred simultaneously at the supplementation level of 0.4 g Fe kg^?1 dry feed of both treatments, while the highest value for the control was 332.5%. Iron accumulations in liver were 2.727, 1.443, and 1.225 ppm, and red blood cell counts were 2.3, 6.0, and 7.0 x 10¹²/l for the same treatments. Supplementation of iron oxide in both nano and macro forms significantly improved the growth and health indices of C. gariepinus up to a concentration of 0.4 g Fe kg^?1 dry feed. Also macro iron oxide was more effective than the nano form in enhancing fish growth within the supplementation levels (0.2?1.6 g kg^?1) considered.     

Effects of Partial and Complete Replacement of Synthetic Cryoprotectant with Carrot (Daucus carota) Concentrated Protein on Stability of Frozen Surimi

ABSTRACT

The study aimed to evaluate the effects of carrot concentrated protein (CCP) as additive on the functional and textural properties of surimi from striped catfish (Pangasianodon hypophthalmus) during six months of frozen storage (?20°C). The CCP (82.22% crude protein) was used as an additive either a lone or with a synthetic cryoprotectant (sucrose-sorbitol-sodium tri-polyphosphate). Control was made with synthetic cryoprotectant only. Molecular weight of CCP was found to be 36 kDa. After six months, the results revealed that up to 50% of synthetic cryoprotectants could be replaced by CCP during frozen storage of surimi. Biochemical parameters such as protein solubility, Ca²⁺ATPase activity, and gel strength decreased significantly (p < .05) during storage. Treatment T-3 (CCP 0.5% + 50% of synthetic cryoprotectant) maintained quality of protein significantly superior (p < .05) in respect to denaturation and other functional and sensory attributes compared to all the treatments. The microstructure images of surimi confirmed that addition of CCP modified the ice crystal growth during frozen storage. This study suggests that CCP can be a potential additive to protect protein from denaturation along with partial replacement of chemical cryoprotectants.     

Effect of Bay (Laurus nobilis L.) Essential Oil on Surimi Gels Nutritionally Enhanced with Salmon and Flaxseed Oils

Bay essential oil (BEO) at 0.5 and 1 g/100 g was added to surimi gels fortified with omega (ω)-3 rich oils. Although the fortification resulted in increased (P < 0.05) susceptibility of surimi to lipid oxidation, 0.5 g/100 g BEO significantly reduced TBARS (P < 0.05). Addition of ω-3 rich oil or BEO improved the texture. Color values of the surimi seafood were improved particularly when BEO was added. Sensory properties, water activity, and pH values were generally within the acceptable range. These results suggest that the incorporation of BEO may allow food manufacturers to nutritionally enhance surimi seafood with beneficial ω-3 rich oils.