Content of total and free amino acids in zooplanktonic food of fish larvae

The content of total and free amino acids in freshwater planktonic rotifers (Brachionus sp.), copepods (Eudiaptomus zachariasi) and groups of Daphnia pulex, Ceriodaphnia sp. and copepodites (Cyclops strenuus) of different sizes was determined. The amino acid content of Artemia salina nauplii on hatching and during fasting was also determined.

Amino acid content was lowest in rotifers and highest in stage III–IV copepodites. The major free amino acids in Cyclops strenuus dry matter were 1.43% arginine, 0.22% histidine, 0.20% alanine, 0.15% glutamic acid and 0.11% lysine. Free arginine content decreased in the daphnids as they increased in size. The content of all free amino acids in fasting Artemia nauplii was lower than in the freshwater zooplankters. The major free amino acids in nauplii were 0.55% proline, 0.41% alanine, 0.34% glycine and 0.37% serine. The content of most free amino acids in nauplii decreased during fasting. The significance of the results are discussed in relation to essential amino acid requirements of fish, and nutrition of fish larvae without fully developed gastrointestinal systems.     

Elution and internal migration of free amino acids in fish meats by soaking in sodium chloride or sorbitol solution

ABSTRACT:   Elution and internal migration of free amino acids (FAA) in fish meats by soaking were investigated when the meat strips were soaked in various concentrations of sodium chloride (NaCl) or sorbitol solution. Rapid decrease of FAA in an earlier phase of soaking was followed by a mild one, irrespective of the kind and the concentration of soaking solution. The loss of FAA by soaking in NaCl solution was slightly larger than that in sorbitol solution. However, regardless of the kinds of soaking solution, the elution of FAA from fish meats by soaking was only dependent on the soaking time, independently of the concentration, namely osmotic pressure of the soaking solution. Conversely, sluggish migration of FAA from the inside to the surface of the meat strips proceeded by soaking. These results suggested that the elution of FAA from fish meats by soaking was driven by a simple diffusion from the surface of the meats to soaking solution, but it was regulated by sluggish migration rate of FAA in fish meats.     

Culture-independent analysis of the bacterial community during fermentation of pa-som,a traditional fermented fish product in Laos

Pa-som is a traditional salty fermented food made from varieties of freshwater fish with garlic and rice in Laos. A similar product, plaa-som, is made in Thailand. To investigate the fermentation process of pa-som, lactic acid production and pH were monitored during laboratory-scale production of pa-som. Furthermore, the variety of bacteria involved and their succession during fermentation were examined using culture-independent polymerase chain reaction (PCR) denaturing gel gradient electrophoresis targeting the 16S ribosomal RNA (rRNA) gene. d- and l-lactic acid production and a decrease in pH were observed in the samples after 1 day of fermentation. The lactic acid content and pH continued to increase and decrease, respectively, until 4 days of fermentation. Overall, six lactic acid bacteria and eight other indigenous bacteria species were detected during pa-som fermentation. Among the lactic acid bacteria detected, two Lactococcus and one Weissella species were detected in samples after 1–4 days of fermentation, suggesting that these three species play major roles in pa-som fermentation from the initial phase. This is the first report to investigate the fermentation process in pa-som at the microbial level. This research approach should be applicable to a wide variety of pa-som and related fermented fishery products in Laos to help understand their microbial diversity and to identify beneficial bacterial species for improving quality.     

杂交鳜与鳜鱼、斑鳜肌肉营养成分和氨基酸含量比较

通过测定鳜鱼、斑鳜和杂交鳜的肌肉营养成分和18种氨基酸含量,结果表明：杂交鳜、斑鳜和鳜鱼的肌肉水分、脂肪、灰分的含量无显著差异（P〉0．05）,杂交鳜与斑鳜的肌肉蛋白质含量无显著差异（P〉0．05）,但均显著高于鳜鱼肌肉的蛋白质含量（P〈0．05）;鳜鱼、斑鳜和杂交鳜的18种氨基酸含量及其组成、18种氨基酸总量（TAA）、人体所需8种必须氨基酸总量（HEAA）及4种呈味氨基酸（天门冬氨孽、谷氨酸、甘氨酸和丙氨酸）的总量（FAA）均无显著差异（（P〉0．05）。     

杂交罗非鱼饲料中豆粕、发酵豆粕和晶体氨基酸替代鱼粉的研究

添加豆粕(soybean meal,SBM)、发酵豆粕(fermented soybean meal,FSBM)和晶体氨基酸(crystalline amino acid,CAA)替代杂交罗非鱼(Oreoehromis niloticus ♀×O.aureus ♂)实用饲料中5%的鱼粉,连续投喂初始体重为9.41±0.05 g的罗非鱼9周后,通过测定罗非鱼的增重率(WGR,%)、特定生长率(SGR,%)、饲料效率(FE,%)、蛋白质效率(PER,%),并进行肝脏分析和血浆分析,比较各组饲料对罗非鱼生长和非特异性免疫的影响.结果表明,发酵豆粕+晶体氨基酸组的WGR、SGR高于其他3组,鱼粉组的FE高于其他3组;PER方面各组间差异不显著,4组饲料对罗非鱼肝脏组成、血浆成分和存活率没有造成显著差异.     

细角螺肌肉氨基酸及脂肪酸组成分析

测定了细角螺(Hemifusus termatamus)腹足部肌肉的氨基酸含量与脂肪酸组成,并与方斑东风螺(Babylonia areolata)、管角螺(Hemifusus tuba)、棘角螺(Hemifusus kawamurai)和鲐鱼(Pneumatophorus japonicus)进行了比较。结果显示,细角螺肌肉中检出17种氨基酸,总含量为肌肉干重的81.03%,高于鲐鱼(79.86%)、方斑东风螺(66.45%)、管角螺(56.94%)和棘角螺(64.42%);肌肉中4种呈味氨基酸(天冬氨酸、谷氨酸、甘氨酸和丙氨酸)的含量为38.49%,占氨基酸总量的47.50%;8种必需氨基酸(EAA)总含量为38.49%,占氨基酸总量的46.94%。细角螺肌肉中共检出20种脂肪酸,其中饱和脂肪酸的含量为65.25%,不饱和脂肪酸的含量为34.75%,不饱和脂肪酸与饱和脂肪酸含量的比值为0.53,低于方斑东风螺(1.15)、管角螺(1.13)和棘角螺(0.69),高于鲐鱼(0.37)。结果表明,细角螺肌肉中必需氨基酸与不饱和脂肪酸含量较丰富,具有较高的营养价值,是一种较为理想的食物蛋白与脂肪来源。     

锈斑蟳肌肉氨基酸和脂肪酸组成分析及营养品质评价

测定了锈斑蟳(Charybdis feriatus)肌肉的氨基酸含量与脂肪酸组成,对其氨基酸含量和脂肪酸组成进行了分析和评价。结果显示,锈斑蟳肌肉干样中共检测出包括牛磺酸在内的19种氨基酸,组成蛋白质的氨基酸总含量为肌肉干重的75.36%,其中,8种必需氨基酸(EAA)的总量为25.41%,占氨基酸(AA)总量的33.73%,非必需氨基酸(NEAA)总量为40.91%,而必需氨基酸与非必需氨基酸的比值(EAA/NEAA)为62.13%;肌肉中4种鲜味氨基酸的含量为28.84%,占氨基酸总量的38.28%;锈斑蟳肌肉中检测出了12种脂肪酸,其中,饱和脂肪酸(SFA)的含量为38.04%,单不饱和脂肪酸(MUFA)的含量为31.58%,多不饱和脂肪酸(PUFA)的含量为29.80%,多不饱和脂肪酸与饱和脂肪酸比值(PUFA/SFA)为0.78,n-3 PUFA与n-6PUFA的比值达到了17.75,多不饱和脂肪酸中EPA和DHA两者的含量达到了20.24%。结果表明,锈斑蟳肌肉中必需氨基酸、鲜味氨基酸含量与不饱和脂肪酸比例较高,具有较高的营养保健价值。     

马氏珠母贝肉的营养成分及其游离氨基酸组成

对马氏珠母贝肉的营养成分及游离氨基酸组成进行了较系统的食品化学特性研究,结果表明：马氏珠母贝含粗蛋白７４．９％（干基）,蛋白质的氨基酸组成中,富含Ｇｌｕ（２．２１％）、Ａｓｐ（１．４５）、Ｇｌｙ（１．０１％）等呈味氨基酸;蛋白质营养价高,氨基酸价为８２,第一限制氨基酸是含硫氨基酸（１９７３年（ＦＡＯ／ＷＨＯ标准）;无机盐含量丰富,尤其是微量元素Ｚｎ和Ｓｅ;游离氨基酸中,牛磺酸含量最高达１．３８％,     

几种牡蛎在保鲜中游离氨基酸和牛磺酸的变化

牡蛎是一种营养丰富的水产动物,曾被誉为“海洋牛奶”［１］。其高营养价值和医疗保健作用,在很大程度上取决于含有较高的风味营养物质。这些物质在细胞内起着调节渗透压的作用,同时也赋予牡蛎所特有的鲜味和营养。据报道［２］,海产动物体内游离氨基酸、牛磺酸等的变化与原有的含量水平、细胞的自溶作用和随之而发生的微生物生长繁殖有紧密关系。８０年代初,日本学者研究鲐、鲣、金枪鱼等在冷藏过程中,从新鲜状态到初期腐败阶段ＦＡＡ含量变化与相关鲜度指标的关系［３．４］ 我国牡蛎主要品种有僧帽牡蛎（Ｏｓｔｒｅａ ｐｌｉａｔｕ…     

Changes in the levels of circulating plasma free amino acids of carp (Cyprinus carpio) after feeding a protein and an amino acid diet of similar composition

A protein diet containing casein as the sole nitrogen source and an amino acid diet of similar composition (except isolated amino acids represented all of the nitrogen) were fed to triplicate groups of yearling carp. The sequence of appearance of free amino acids in the plasma of carp at 0, 2, 4, 8 and 16 h after feeding the two diets was examined.The circulating levels of all plasma free essential amino acids were in highest concentrations at 4 h after feeding the casein diet, except for arginine which declined slightly from 2 to 4 h. After feeding the amino acid diet, plasma free arginine and lysine were at peak levels at 2 h after feeding, while others peaked by 4 h.Glutamic acid and aspartic acid were detected in very low concentrations in the plasma relative to their levels in the diets, while proline was found in the highest concentrations of all other amino acids.Essential amino acid levels in the plasma were found to be positively correlated with their levels in the diets, while non-essential amino acids were not.     

家蝇蛆粉替代鱼粉对凡纳滨对虾肌肉营养成分、氨基酸和肌苷酸含量的影响

采用等蛋白替代方式,以家蝇蛆粉(housefly maggot meal)分别替代饲料中0、20%、40%、60%、80%和100%的鱼粉,配制6种等氮等能的饲料,饲养初始体质量(0.56±0.03)g的凡纳滨对虾(Litopenaeus vannamei),相应记为G0、G20、G40、G60、G80和G100实验组。养殖45 d后测定对虾肌肉的常规成分和氨基酸、肌苷酸含量,研究家蝇蛆粉对凡纳滨对虾肌肉品质的影响。结果显示,凡纳滨对虾肌肉粗蛋白和灰分含量随家蝇蛆粉替代水平的增加而升高,其中G100组粗蛋白含量和G80、G100组灰分含量显著高于G0组(P<0.05);水分和粗脂肪含量各组之间差异不显著。各组肌肉游离氨基酸中谷氨酸、丙氨酸等鲜味氨基酸和游离鲜味氨基酸总量之间无显著性差异;除G40组外,G20-G100组游离必需氨基酸总量显著高于G0组(P<0.05);与G0组相比,替代组游离精氨酸含量显著增加(P<0.05),游离赖氨酸含量随替代水平的增加而显著降低(P<0.05);G20组游离氨基酸总量显著高于G0组(P<0.05),其他各组之间差异不显著。替代组肌肉结合氨基酸中天冬氨酸、谷氨酸、甘氨酸和丙氨酸等鲜味氨基酸、必需氨基酸和氨基酸总量与G0组相比差异均不显著。G20-G80组肌肉肌苷酸含量与G0组相比差异不显著,G100组显著升高(P<0.05)。结果表明,当家蝇蛆粉替代鱼粉水平不超过60%时,除凡纳滨对虾肌肉游离精氨酸含量显著升高外,对肌肉常规营养成分组成和必需氨基酸、鲜味氨基酸和肌苷酸含量无显著性影响。     

Hydrolyzates produced from mackerel Scomber japonicus skin by the pressurized hydrothermal process contain amino acids with antioxidant activities and functionalities

The production of amino acids with antioxidant activities and functional properties from protein hydrolyzates of freeze-dried and supercritical carbon dioxide (SC-CO₂)-extracted mackerel skin by pressurized hydrothermal hydration (PHH) at different temperatures (150–240 °C) and pressures (12–210 bars) was investigated. The highest yield of amino acid in freeze-dried and SC-CO₂-extracted mackerel skin hydrolyzates was 121.93 ± 1.80 and 122.96 ± 2.84 mg/g, respectively, at 240 °C and 210 bars. Nine essential amino acids were identified in both skin hydrolyzates, of which histidine was the most abundant. All essential amino acids showed a temperature stability up to 240 °C, with the exception of threonine and histidine. The antioxidant activity of the hydrolyzates, as demonstrated in the DPPH, ABTS, hydroxyl radical, metal chelating, and reducing power assays, increased with increases in temperature and pressure; it was high in both hydrolyzates at 240 °C and 210 bars. In terms of functional properties, hydrolysis at different temperatures and pressures increased protein solubility to above 59 % over a wide pH range (3.5–9.5). When the temperature and pressure increased, the emulsifying activity index, emulsion stability, foaming capacity, and foam stability of both hydrolyzates decreased, possibly caused by the shorter peptide chain length. We conclude that protein hydrolyzates produced from mackerel skin can be used in food-related industries as good additives.     

真鲷胚胎及胚后发育各阶段氨基酸组成的研究

在真鲷 (Ｐａｇｒｏｓｏｍｕｓｍａｊｏｒ)各发育阶段 ,蛋白质是主要的营养需求成分 ,而蛋白质的营养价值又取决于蛋白质自身的氨基酸 ,特别是必需氨基酸的组成与含量。真鲷在不同的发育阶段对氨基酸的需求也有差异 ,尤其是在胚后发育阶段。目前认为 ,饵料蛋白质中的氨基酸组成与含量同动物本身氨基酸组成与含量相似者 ,可视为最好的饵料[1] 。关于真鲷生理发育各阶段的氨基酸组成的研究国内未见报道[2 ] 。因此 ,研究真鲷本身氨基酸的组成与含量 ,可为真鲷的营养与生理学研究提供基础资料 ,也可为真鲷饵料的研究提供科学依据。本文报道真鲷…     

Comparison of two assay methods for determination of nutrient and energy digestibility in fish

Determination of digestible energy (DE) and digestibility of protein, lipid and nitrogen-free extract (NFE) was studied by two methods in rainbow trout held in fresh water. The whole diet-substitution method used a reference diet composed of casein, dextrinised maize starch and fish oil supplied with minerals and vitamins. Test samples of fish meal were substituted for the reference diet at 25.0, 37.5, 50.0 and 75.0% in the test diets. Energy values and nutrient digestibilities of test samples were calculated from the values determined for the reference and the test diets using the substitution principle. The ingredient-substitution method used the same reference diet but in the test diets, test samples of fish meal were substituted for casein at levels of 15.0, 25.0, 30.0, 45.0 and 50.0%. Energy values and protein digestibility of the casein were determined in initial studies and used together with those of the reference diet to determine nutrient and energy digestibilities of the test samples. Thus, in the whole diet-substitution method, the digestibility of the test substance was determined relative to that of the reference diet, while in the ingredient-substitution method the values are relative to those of casein.

The study revealed no major differences between the two methods with regard to determined values and variability, and for both methods nutrient and energy digestibilities could be determined with a high level of accuracy. The ingredient-substitution method revealed a positive effect of fish meal on NFE digestibility, leading to a slight overestimation of the DE in fish meal that decreased when levels of inclusion increased.

For the whole diet-substitution method, inclusion of fish meal reduced the level and increased the digestibility of NFE in the test diets compared with that of the reference diet due to dilution, and consequently the determined DE value of the diets increased, which in turn led to an overestimation of the DE value of the fish meal. Since the casein-based ingredient-substitution method is based on a reference substance of presumably constant composition and digestibility, this method allows for comparison of results over time within the same laboratory as well as between laboratories, and may therefore be recommended.     

Isolation and characterization of a rhabdovirus from co-infection of two viruses in mandarin fish

Co-infection of two viruses has been observed in mandarin fish (Siniperca chuatsi), but the two viruses have not been characterized. In this study, a rhabdovirus has been isolated from the co-infected two viruses extracted from the diseased mandarin fish, and its morphological structure and partial biochemical and biophysical characteristics have been observed and analyzed. The isolated rhabdovirus has a typical bullet shape, and is therefore called S. chuatsi rhabdovirus (SCRV). And, the isolated rhabdovirus produced a higher titer (10^8.5 TCID₅₀ ml^− 1) than did the co-infecting viruses (10^6.5 TCID₅₀ ml^− 1). Subsequently, the viral genome RNA was extracted, and used as template to clone the complete nucleoprotein (N) gene by RT-PCR amplification. Cloning and sequencing of the SCRV N protein revealed 42%-31% amino acid identities to that of trout rhabdovirus 903/87 and the rhabdoviruses in genus Vesiculovirus. SDS-PAGE separation of the isolated SCRV and other two rhabdoviruses also revealed obvious polypeptide profile difference. Moreover, the anti-SCRV N protein antibody was prepared, and the anti-SCRV N protein antibody only could recognize the SCRV N protein, whereas no antigenicity was detected in other two rhabdoviruses. The data suggested that the SCRV should be a rhabdovirus member related to the genus Vesiculovirus in the Rhabdoviridae.     

Absorption, assimilation and catabolism of individual free amino acids by larval Atlantic halibut (Hippoglossus hippoglossus)

Following the completion of the lecithotrophic phase, most marine larvae rely on an incompletely developed digestive tract to absorb amino acids (AA) and other nutrients needed for rapid growth. Despite their undeveloped state, larvae must absorb nutrients in sufficient amounts to fuel exceptionally high rates of growth. This study examined the ability of larval Atlantic halibut to absorb, assimilate and catabolise dispensable (alanine, glutamate) and indispensable (arginine, lysine) dietary free amino acids (FAA) using tube-fed AA solutions with ¹⁴C tracers. Absorption of FAA was rapid with an average of 71% absorbed from the gut within 30 min after tube feeding. Evacuation of FAA by larvae was low, averaging only 6% of tube-fed dose. Dispensable amino acids (DAA) were catabolised in greater proportion (17%) than indispensable FAA (54%). Saturation of FAA transporters was not attained under the present conditions (20 mM, 20% midgut filling). Absorption rates did not differ significantly between the four FAA.     

Pilot study of the relationship of free amino acids in serum and in the cerebrospinal fluid of horses

In a blind study serum and cerebrospinal fluid (CSF) of control horses and of horses in hepatic coma after chronic food intoxication with Senecio alpinus were collected simultaneously and the composition of free amino acids was determined. The hepatic encephalopathy index in serum (less than 1.65) and in CSF (less than 1.11) of liver patients was distinctly less than to the control values in serum (greater than 2.42) and in CSF (greater than 1.49). The serum concentrations of glutamic acid in hepatic coma were elevated five-fold in comparison to the controls. An indication of ammonia decontamination was that nearly ten-fold higher values of glutamine were found in the cerebrospinal fluids of patients than in serum. In comparison to controls the serum levels of glutamine in horses with hepatic encephalopathy were decreased by the factor 0.7.     

鞍带石斑鱼肌肉营养成分及氨基酸含量分析

采用常规营养物质测定方法对鞍带石斑鱼Epinephelus lanceol肌肉营养成分及氨基酸含量进行了定量分析,并开展了相关营养分析。结果表明,鞍带石斑鱼新鲜肌肉中粗蛋白含量19．5％、粗脂肪含量7．69％、水分含量70．5％、粗灰分含量1．01％,氨基酸种类有18种,其中8种必需氨基酸含量为43．43％。鞍带石斑鱼作为一种高蛋白、氨基酸含量丰富的养殖鱼类,具有较高的食用和营养价值。     

Seasonal variations of free amino acids and nucleotide-related compounds in the muscle of cultured Taiwanese puffer Takifugu rubripes

SUMMARY: Seasonal variation in the level of extractive nitrogenous components was investigated in the muscle of puffer Takifugu rubripes cultured in two different areas of Taiwan. There were no seasonal and regional variations in the proximate composition of the fish. Of the free amino acids (FAA) in the muscle of puffer, the predominant one was taurine, followed by glycine, lysine, and alanine. Among nucleotide-related compounds, inosine monophosphate (IMP) and guanosine monophosphate (GMP) were the most prominent compounds. The total nucleotide-related compounds in the muscle of puffer were higher in July and November than those in the other months. The level of total taste-active components including glycine, alanine, arginine, GMP, IMP, and adenosine 5'-monophosphate was much higher in the muscle of puffer collected from July to January. Therefore, the puffer is probably more palatable in these periods.