The Influence of Egg White and Tumbling on Proximate Composition and Protein Fractions of Fresh Catfish Muscle

Tumbling increased the percentage of extracted myofibrillar protein while reducing sarcoplasmic protein extraction in processed raw fish muscle as compared to the non-tumbled control group. Egg white increased the non-protein nitrogen (NPN) and pH and lowered TBA values. The electrophoretic pattern of the treatments was not noticeably different from fresh (zero time) tissue which might be due to minimal proteolysis occuring during the tumbling process. There were significant positive correlations between total moisture and myofibrillar protein fractions, sarcoplasmic protein and NPN, total lipid and TBA, and pH and ash content. Also, negative relationships were determined between myofribillar protein and NPN and between pH and NPN. We concluded that the tumbling technique and egg white addition are useful practices to increase functional properties of fish muscle so it can be utilized to produce an acceptable restructured fish product.     

Comparison of horse mackerel and tilapia surimi gel based on rheological and <Superscript>1</Superscript>H NMR relaxation properties

ABSTRACT:   Horse mackerel and tilapia surimi were subjected to six different heat and pressure treatments in order to compare gelation characteristics of easy- and difficult-setting gels, that is, temperature dependence, by observing rheological properties and microscopic molecular mobility. The stress–relaxation and proton spin–spin relaxation time (¹H T ₂) of water were measured for all treated gels. Horse mackerel gel demonstrated higher elasticity, large distribution of the stress–relaxation process, and smaller water ¹H T ₂ than tilapia in both heat and pressure treatments. The water ¹H T ₂ was steeply increased in the pressure treatment at around 294 MPa for both fishes. In contrast, the ¹H T ₂ rarely changed in the heat treatment in spite of the considerable change in rheological properties. From the experimental results, it is considered that the gelation of horse mackerel (easy setting) surimi is induced by highly unfolding and re-aggregation of protein, which contributes to the formation of a strong network structure compared with tilapia in both heat and pressure treatments, and that pressure treatments hardly improve the gel strength of tilapia (difficult setting) surimi. The water ¹H T ₂ measurement was used effectively in order to study gelation characteristics of easy- and difficult-setting fish through observing its molecular dynamics.     

Changes in enzymatic and structural properties of grass carp fast skeletal myosin induced by the laboratory-conditioned thermal acclimation and seasonal acclimatization

ABSTRACT:   Myosins were prepared from fast skeletal muscles of grass carp thermally acclimated to 10, 20 and 30°C in the laboratory as well as from those seasonally acclimatized and collected in January (winter) 2003 and May (spring), August (summer) and November (autumn) 2002. The maximal initial velocities ( V _max) of actin-activated Mg²⁺-ATPase activity for myosins from the 10°C-acclimated and winter grass carp were 1.7–1.8-fold as high as those from the 30°C-acclimated and summer fish. The inactivation rate constant ( K _D) of Ca²⁺-ATPase for myosin from the 10°C-acclimated grass carp was three to fourfold higher than those for myosins from the fish acclimated to 20°C and 30°C, whereas myosin from winter grass carp was about sevenfold as high as that for myosin from summer fish. Myosins from spring and autumn fish showed K _D values comparable to those of the fish acclimated to 30°C and 10°C, respectively. In differential scanning calorimetry analysis, the transition temperature ( T _m) was observed near 38°C and 45–46°C with most myosins. However, the lowest T _m at 32–33°C was given as one of the major endotherms in myosins from the 10°C-acclimated, autumn and winter fish. These responses of grass carp to changed environmental temperatures were almost similar to those for common carp reported previously.     

Qualitative and quantitative changes of F<Subscript>o</Subscript>F<Subscript>1</Subscript>-ATPase in Japanese flounder and red sea bream associated with rearing temperatures

ABSTRACT:   Fast skeletal muscles of Japanese flounder Paralichthys olivaceus and red sea bream Pagrus major were examined for quantitative and qualitative changes of mitochondrial ATP synthase (F_oF₁-ATPase) in association with rearing temperatures. The specific activities of F_oF₁-ATPase from Japanese flounder reared at 10°C, 15°C and 25°C for 4 weeks were determined to be 81 ± 11, 74 ± 13 and 83 ± 11 nmol/min·mg mitochondrial protein, respectively. The corresponding activity from red sea bream reared at 8°C for 5 weeks was determined to be 65 ± 9 nmol/min·mg mitochondrial protein, which was higher than 33 ± 9 nmol/min·mg mitochondrial protein in fish reared at 23°C. The contents of α- and β-F₁-ATPase in total mitochondrial proteins were not significantly different between fish reared at different temperatures for the two fish species. However, the contents of β-F₁-ATPase in the total fast skeletal muscle extracts, prepared from Japanese flounder reared at 10°C, were 2.1- and 2.9-fold higher than those for fish reared at 15°C and 25°C, respectively. The corresponding content from red seabream reared at 8°C was 2.2-fold higher than that for fish reared at 23°C. Therefore, the changes in F_oF₁-ATPase depending on rearing temperatures were species-specific.     

Total mercury and methylmercury levels in commercially important fishes in Japan

ABSTRACT:   The distribution of mercury in the muscle and other tissues was determined in 23 species of fishes and invertebrates. This study reveals species-specific patterns of mercury accumulation in the muscle of tuna and alfonsino. Consistently high levels of total mercury were found in Beryx splendens (0.78 ± 0.56 µg/g), Atlantic Thunnus thynnus (0.42 ± 0.06 µg/g), Pacific T. thynnus (0.59 ± 0.34 µg/g), Thunnus obesus (0.98 ± 0.34 µg/g), Makaira nigricans (0.56 ± 0.05 µg/g), Tetraptrus audax (0.51 ± 0.08 µg/g), and Xiphias gladius (0.47 ± 0.24 µg/g). Other fish species had lower levels of total mercury or methylmercury in muscle than the maximum permitted level of mercury in fish in Japan (0.4 µg/g). Total mercury and methylmercury levels in the muscles of T. thynnus , T. obesus, and B. splendens were closely correlated with body weight.     

Characterization of grouper nervous necrosis virus (GNNV)

Grouper nervous necrosis virus (GNNV) was isolated from moribund grouper larvae, Epinephelus sp., using a fish cell line GF-1. The present study describes the biochemical and biophysical properties of GNNV and the expression of GNNV in diseased grouper larvae. Viral protein was detectable in most of the GNNV-infected GF-1 cells by the fluorescent antibody technique (FAT) after 12 h post-infection (p.i.), although no cytopathic effect (CPE) appeared at that time. Clear CPE developed on the third day, and complete disintegration of the monolayer occurred over the subsequent two days. The infectivity of GNNV can be blocked following treatment at 60 °C for 1 h. GNNV was sensitive to pH 3 and pH 10–12 with a 4 log₁₀ drop in infectivity. Purified GNNV was analysed by SDS–PAGE, and then stained with periodic acid silver. The positive staining indicated that its two capsid proteins were glycoproteins. Genomic RNAs of GNNV were extracted from purified virions and analysed. The molecular weights of genomic RNAs were 1.02 × 10⁶ and 0.50 × 10⁶ Da. The T2 region of the coat protein gene of GNNV was amplified by polymerase chain reaction (PCR), and the multiple alignment of the T2 sequence of two GNNV isolates with four genotypes of fish nodaviruses revealed that these two isolates (GNNV9410 and GNNV9508) belong to the red-spotted grouper nervous necrosis virus (RGNNV) genotype. The tissue distribution of GNNV in naturally infected grouper larvae was investigated by in situ hybridization using a dig-labelled probe, which showed that GNNV was not only detected in the brain and retina, but also in the gill, skeletal muscle, liver, pyloric gland, intestine and blood cells in the heart.     

Effect of dietary lysine and methionine supplementation on growth, nutrient utilization, carcass compositions and haemato-biochemical status in Indian Major Carp, Rohu (Labeo rohita H.) fed soy protein-based diet

An 8-week feeding trial was conducted in flow through system to examine the effects of dietary supplementation of lysine and methionine on growth, nutrient utilization, haemato-biochemical status and carcass compositions in Indian major carp, rohu, Labeo rohita fingerlings (average weight 6.32 ± 0.06 g). Four experimental soy protein-based diets D ₀ (without lysine or methionine supplementation), D ₁ (lysine supplementation alone), D ₂ (methionine supplementation alone) and D₃ (both lysine and methionine supplementation) were fed to triplicate groups. l -Lysine and dl -methionine were added to the diets containing 550 g kg⁻¹ soybean meals at 4 and 7 g kg⁻¹ of dry diet respectively. Significant higher weight gain, specific growth rate (SGR), protein efficiency ratio (PER), dry matter retention, nitrogen retention, total ash retention, whole carcass protein, haemoglobin concentration, haematocrit value, total erythrocytic count, total leucocytic count, plasma glucose and plasma total protein and lower FCR, per cent lipid retention and whole body moisture content were observed in fish fed soya protein-based diet supplemented with both lysine and methionine than that of fish of other dietary groups at the end of 8 weeks feeding trial. Although fish fed diet supplemented with either methionine or lysine did not show any significant differences of growth performances, feed utilization, carcass composition and haemato-biochemical status, fish of both of these dietary groups showed significantly better growth performances, feed utilization, carcass composition and haemato-biochemical status than that of fish fed diet without lysine and methionine supplementation.     

Pharmacokinetics of oxolinic acid in gilthead sea bream, Sparus aurata L.

This is the first study on the pharmacokinetic parameters of oxolinic acid (OA) in gilthead sea bream, Sparus aurata L. The kinetic profile of OA was studied after a single intravascular injection (20 mg kg⁻¹) in 100 g fish at 20 °C. The distribution half-life ( t _1/2α) and the elimination half-life ( t _1/2β) of the drug were found to be short (0.51 and 12.60 h, respectively). The drug penetration from the plasma to the tissues was adequate as the apparent volume of distribution of the drug at steady-state ( V _d(ss)) was found to be 2.11 L kg⁻¹. The mean residence time ( MRT ) of OA was short (14.25 h) and the total clearance rate ( Cl _T) of the drug was low (0.15 L kg⁻¹ h⁻¹). The bioavailability ( F %) of OA following oral administration (30 mg kg⁻¹) was also low (14%). Maximum values were observed for muscle at 0.5 h after injection, with levels declining as with subsequent sampling. At the first two time points (0.5 and 1 h) plasma levels of OA were higher than muscle, however, the reverse was evident for subsequent samples. Following oral administration, highest muscle levels were found at 16 h and, with the exception of the 24-h sampling, muscle OA concentrations were higher than plasma at all time points. The fast elimination of OA suggests short withdrawal times with reference to human consumption of treated fish.     

鲢鳙鳊鲫鱼肉的蛋白质组成及分离研究

我国４种淡水鱼鲢镛鳊鲫的蛋白质组成基本一致,即粗蛋白质为１７．２ｇ／１００ｇ－１８．３ｇ／１００ｇ湿肉,其中肌原纤维蛋白质占总氮的６０．７－６４．４％、肌浆蛋白质为２６．１－３３．２％,总基质蛋白质为９．０－２０．８％,非蛋白 １９３ｍｇＮ３４７ｍｇＮ／１００ｇ湿肉。     

Gelation of low salt soluble proteins from scallop adductor muscle in relation to its freshness

ABSTRACT: The low salt extract from scallop striated adductor muscle contained extra proteins in addition to sarcoplasmic proteins and was turned into a gel upon standing or immediately by the addition of Ca²⁺. The amount of extra protein, which was composed of a large amount of actin and a small amount of myosin, decreased with a decrease in adenosine triphosphate (ATP) content in the muscle during storage at 5°C. Actin was easily extracted from scallop myofibrils in low salt solution with ATP at 1 mM or above. Furthermore, ATP was required to induce the gelation of the low salt extract. A visual observation of the gelation of low salt extract is therefore a simple and easy method to inspect prerigor state of scallop adductor muscle.     

Basin geochemistry and isotopic ratios of fishes and basal production sources in four neotropical rivers

Abstract –  We analysed stable carbon and nitrogen isotopic ratios of dissolved inorganic carbon (DIC), plants, detritus and fishes to estimate the relative importance of dominant production sources supporting food webs of four Venezuelan rivers with divergent geochemical and watershed characteristics. Based on samples taken during the dry season at each site, fishes from two nutrient-poor, blackwater rivers had significantly lower δ ¹³C values (mean = −31.4‰ and −32.9‰) than fishes from more productive clearwater and whitewater rivers (mean = −25.2‰ and −25.6‰ respectively). Low carbon isotopic ratios of fishes from blackwaters were likely influenced by low δ ¹³C of DIC assimilated by aquatic primary producers. Although floodplains of three savanna rivers supported high biomass of C₄ grasses, relatively little carbon from this source appeared to be assimilated by fishes. Most fishes in each system assimilated carbon derived mostly from a combination of microalgae and C₃ macrophytes, two sources with broadly overlapping carbon isotopic signatures. Even with this broad overlap, several benthivorous grazers from blackwater and whitewater rivers had isotopic values that aligned more closely with algae. We conclude that comparative stable isotopic studies of river biota need to account for watershed geochemistry that influences the isotopic composition of basal production sources. Moreover, isotopic differences between river basins can provide a basis for discriminating spatial and temporal variation in the trophic ecology of fishes that migrate between watersheds having distinct geochemical characteristics.     

Effects of Dietary Chlorella ellipsoidea Supplementation on Growth, Blood Characteristics, and Whole-Body Composition in Juvenile Japanese Flounder Paralichthys olivaceus

The study was conducted to investigate the effects of dietary Chlorella powder (C) supplementation on growth performance, blood characteristics, and whole-body composition in juvenile Japanese flounder Paralichthys olivaceus . Four experimental diets were supplemented with C at 0, 1, 2 and 4% (C₀, C₁, C₂, and C₄) on a dry-weight basis. Three replicate groups of fish averaging 1.13 ± 0.02 g (Mean ± SD) were randomly distributed in each aquarium and fed one of four experimental diets for 12 wk. After 12 wk of the feeding trial, fish fed C₂ diet had higher weight gain (WG), feed efficiency (FE), and protein efficiency ratio (PER) than did fish fed C₀ and C₁ diets ( P 0.05); however, there was no significant difference among fish fed C₁ and C₄ diets, and among fish fed C₂ and C₄ diets ( P > 0.05). Fish fed C₂ and C₄ diets had a lower serum cholesterol level than did fish fed C₀ and C₁ diets ( P 0.05). Fish fed C₂ and C₄ diets had a lower body fat than did fish fed C₀ ( P 0.05). These results indicate that dietary supplementation of 2% Chlorella powder in the commercial diets could improve growth, feed utilization, serum cholesterol level, and whole-body fat contents in juvenile Japanese flounder.     

Effect of the protein/energy ratio on the growth of Mediterranean yellowtail (Seriola dumerili)

Yellowtails weighing 490 g were fed five experimental diets with different protein/energy ratios, 24.6, 26.9, 28.9, 31.8 and 35.8 g MJ⁻¹, for 152 days. The energy content was similar in all the diets and the protein and lipid levels were 40/26, 45/26, 50/18, 50/26 and 55/18 %CP/%CL respectively. The final weight and SGR were lower in fish fed diets with a lower PD/ED ratio (24.6 and 26.9 g MJ⁻¹), and the mortality of fish fed diet 24.6 g MJ⁻¹ was higher. In fact, only fish that consumed diet 35.8 g MJ⁻¹ had a haematocrit and a normal erythrocyte number similar to that in healthy yellowtail. No differences appeared in feed intake and feed conversion ratio. Digestible energy ingestion was similar for all the diets and digestible protein intake was also low for 24.6 compared with 35.8 g MJ⁻¹. The meat composition was similar for fish fed all the diets, but the profiles of muscle fatty acids indicated an increasing content of saturates and n-3 HUFA, while the levels of monounsaturates decreased, corresponding to an increase in the PD/ED relation. The economic conversion ratio and economic profit index were not different for fish fed the experimental diets.     

Myofibrillar proteolysis by myofibril-bound serine protease from white croaker <Emphasis Type="Italic">Argyrosomus argentatus</Emphasis>

ABSTRACT:   The modori phenomenon is defined as heat-induced myofibrillar degradation caused by endogenous serine protease(s) of fish muscle during Kamaboko fish meat gel production. This study was undertaken to analyze myofibrillar proteolysis of white croaker Argyrosomus argentatus muscle, which is an ingredient of high quality Kamaboko, by myofibril-bound serine protease (MBSP) under conditions corresponding to the modori phenomenon. White croaker MBSP was stable between pH 2–11 and below 65°C, and about 60% of its initial activity remained after incubation for 2 h under the conditions at 65°C and pH 7.5. About 60% of the enzyme activity was suppressed by 0.5 M NaCl. White croaker MBSP degraded various myofibrillar proteins between 40 and 70°C and pH 6.0–9.0, and preferentially degraded myosin heavy chain rather than other myofibrillar proteins. The enzyme degraded the myosin heavy chain most strongly at 55°C and pH 7.0, and a major part of the bands of myosin heavy chain and its degradation products disappeared for a period of 2 h. These degradation characteristics are very similar to those observed during the modori phenomenon, indicating that MBSP could be a modori-inducing protease involved in the modori phenomenon of white croaker Kamaboko production.     

Nutritional evaluation of waste date fruit as partial substitute for soybean meal in practical diets of juvenile Nile tilapia, Oreochromis niloticus L.

The potential of waste date meal (WDM; low-quality date palm, Phoenix dactylifera L.) as a carbohydrate source in formulated diets for Nile tilapia was evaluated. Four isocaloric-practical diets (15.7 kJ g⁻¹) were formulated incorporating WDM at 0, 100, 200 and 300 g kg⁻¹ levels as partial substitutes for soybean meal (SBM). These were designated D₀ [284 g crude protein (CP) and 383 g carbohydrate (CHO) kg⁻¹ diet], D₁ (279 g CP and 446 g CHO kg⁻¹ diet), D₂ (207 g CP and 495 g CHO kg⁻¹ diet) and D₃ (175 g CP and 578 g CHO kg⁻¹ diet). Each diet was fed to three replicate groups of 30 fish [20.20 ± 0.09 g (±SE)] for 75 days. No feed-related mortality was observed during the entire experimental period. Final body weight (FBW) and specific growth rate (SGR) in the different treatments were statistically not significantly different ( P  > 0.05). Protein efficiency rate (PER) was lowest in diet D₀ and increased with decrease of SBM content (D₁–D₃). A significant increase in whole body lipid content was recorded in fish fed diets D₂ and D₃. Results showed that WDM could be a substitute for SBM up to 300 g kg⁻¹ in practical Nile tilapia diets without compromising growth.     

Influence of interposition of pink muscle fiber into dorsal ordinary muscle on 5'-IMP degrading activity in various fish species

ABSTRACT: To clarify the cause of differences in the temporal change of K -value among fish species living in the same habitat water temperature, the influence of the interposition of pink muscle fibers into dorsal ordinary muscle on 5'-inosine monophosphate (5'-IMP) degrading activity was examined. Fourteen fish species from the Sakishima Islands (habitat water temperature 28°C) and from Nagasaki (habitat water temperature 17°C) were used for the sample fishes. Each of 5'-IMP and ρ-nitrophenol phosphate (ρ-NPP) degrading activities showed a peak at near pH 8.0 and near pH 5.0, respectively. These activities were somewhat higher in fish from Nagasaki than in fish from the Sakishima Islands. The interposition percentage of pink muscle fibers into dorsal ordinary muscle correlated significantly ( P < 0.05) with the 5'-IMP degrading activity at pH 7.0. Furthermore, the activity at pH 7.0 correlated significantly ( P < 0.001) with the increasing rate of K -value at 32°C (ΔK₃₂). These results suggest that the difference in ΔK₃₂ among fish species in the same habitat water temperature might be caused by differences in 5'-IMP degrading activity because of the differences in the interposition rates of pink muscle fibers into dorsal ordinary muscle.     

The dietary protein requirement of a bagrid catfish, Mystus nemurus (Cuvier & Valenciennes), determined using semipurified diets of varying protein level

Triplicate groups of Mystus nemurus (Cuvier & Valenciennes) were fed isoenergetic semipurified diets containing seven dietary protein levels from 200 to 500 g kg^–1 diet for 10 weeks. Dietary protein was supplied by graded amounts of a protein mixture (tuna muscle meal:casein:gelatine) at a fixed ratio of 50:37.5:12.5. Mystus nemurus fingerlings of initial weight 7.6 ± 0.2 g were fed close to apparent satiation at 2.5% of their body weight per day in two equal feedings. Growth performance and feed utilization efficiency increased linearly with dietary protein level from 202 to 410 g kg^–1 diet and declined with protein levels of 471 g kg^–1 diet or above. Protein efficiency ratio and apparent net protein utilization started to decline when the fish were fed with dietary protein levels exceeding 471 g kg^–1 diet. Fish fed with lower protein diets (202–295 g kg^–1 diet) had significantly ( P  < 0.05) higher carcass lipid content compared with fish fed with higher protein diets. Carcass lipid contents were inversely related to moisture content. Dietary protein did not significantly affect fish carcass protein and ash content. Using two-slope broken-line analysis, the dietary protein requirement for M. nemurus based on percentage weight gain was estimated to be 440 g kg^–1 diet with a protein to energy ratio of 20 mg protein kJ^–1 gross energy. This level of protein in the diet is recommended for maximum growth of M. nemurus fingerlings weighing between 7 and 18 g under the experimental conditions used in this study.     

Microbial Phytase Supplementation in Rohu, Labeo rohita, Diets Enhances Growth Performance and Nutrient Digestibility

Abstract.— A feeding trial was conducted for 60 d to study the effect of dietary microbial phytase on growth performance and nutrient digestibility of rohu, Labeo rohita , fingerlings. One hundred and twenty fingerlings (average initial weight: 9.17 g/fish) were equally distributed into five experimental tanks, each with four replicates. Five isonitrogenous (35%) and isocaloric (16.79 kJ/g) diets were prepared from plant-based ingredients, supplemented with microbial phytase at the level of 0, 250, 500, 750, and 1000 U/kg diets and fed to T₀, T₁, T₂, T₃, and T₄ groups, respectively. Weight gain %, food conversion ratio, protein efficiency ratio, and apparent net protein utilization were significantly ( P  < 0.05) improved in groups fed phytase-supplemented diets compared to control, the highest being observed in T₃ group. Maximum apparent digestibility of phosphorus and crude protein was recorded in T₃ group. Bone ash, phosphorus (P), and calcium (Ca) contents were also significantly ( P  < 0.05) increased in phytase-fed groups. However, maximum was recorded in T₃ group. Results from the present study indicated that addition of 750 U microbial phytase/kg diets effectively improved nutrient utilization, bone mineralization, and hence growth of L. rohita fingerlings.     

Comparing trophic position of stream fishes using stable isotope and gut contents analyses

Abstract –  Stable isotope analysis (SIA) and gut contents analysis (GCA) are commonly used in food web studies, but few studies analyse these data in concert. We used SIA (δ¹⁵N) and GCA (% composition) to identify diets and trophic position (TP) of six stream fishes and to compare TP estimates between methods. Ordination analysis of gut contents identified two primary trophic groups, omnivores and predators. Significant differences in TP_GCA and TP_SIA were similar in direction among-species and among-trophic groups; neither method detected seasonal changes in omnivore diets. Within-species TP_GCA and TP_SIA were similar except for one omnivore. TP_GCA was less variable than TP_SIA for predators, but variation between methods was similar for omnivores. While both methods were equally robust at discriminating trophic groups of fishes, TP_SIA is less laborious to estimate and may facilitate cross-stream comparisons of food web structure and energy flow.