不同贮藏温度下大菱鲆品质变化及货架期预测模型的建立

为探究大菱鲆(Scophthalmus maximus)在不同贮藏温度下品质特性与货架期的关系,将大菱鲆贮藏在-3℃、0℃、4℃、10℃和15℃温度下,测定其感官品质、挥发性盐基总氮(TVB-N)、菌落总数、硫代巴比妥酸值(TBA)、电导率的变化,并且观测肌肉的微观结构;采用低场核磁共振技术(Low-field nuclear magnetic resonance, LF-NMR)分析鱼肉中水分迁移状况,并且建立了TVB-N及菌落总数与贮藏时间和温度的动力学模型。研究发现,随着贮藏时间的延长,5种不同贮藏温度下鱼肉中不易流动水均减少,货架期终点各贮藏温度下的样品相对于新鲜鱼肉,其肌纤维结构均由紧密变得疏松;TVB-N和菌落总数变化预测模型中的活化能和指前因子分别为79.50、75.07 kJ/mol和1.3×10^14、7.62×10^12。选用10℃进行验证性试验,结果显示实测值与预测值相对误差在10%以内。因此,可根据TVB-N值及菌落总数对大菱鲆贮藏在-3℃~15℃的货架期进行实时预测。     

A simple and rapid method for the analysis of fish histamine by paper electrophoresis

ABSTRACT:   The described analytical method for histamine determination in fish and seafood consists of sample extraction, adsorption onto a paper disc, application of the paper disc onto electrophoresis paper, electrophoresis for only 10 min, drying, and color developing by Pauly's reagent. Histamine can be satisfactorily detected and completely separated from histidine, carnosine and other Pauly reagent-positive compounds. This method does not require expensive instrumentation and any tedious pretreatment to eliminate potential interference by other imidazole compounds, such as histidine or carnosine. This method can be used to detect histamine in multiple fish and seafood samples simultaneously that contain as little as 15 p.p.m. histamine (1.5 mg/100 g).     

淡腌黄鱼在不同温度下贮藏的微生物及品质变化

对淡腌黄鱼在5、10、15、25℃下贮藏的微生物及品质变化进行研究,通过检测贮藏期间微生物生长情况、过氧化值(POV)及挥发性盐基氮(VBN)的变化,并结合感官质量的变化,确定了在不同温度下贮藏产品的货架期,对产品货架期腐败终点的指标值进行了准确的描述。结果表明在初期腐败时,微生物生长最大值约为8～9log10CFU·g-1,VBN约为30～40mg·100g-1,POV值在保藏期间均出现峰值,其变化情况与细菌总数、感官评分及VBN的变化保持一致。而5、10、15、25℃的货架期分别是20、14、8、4.5d。真空包装的淡腌黄鱼在4种温度条件下贮藏,产品的货架期较短,且产品腐败的主要原因是微生物腐败,化学腐败不是其主要腐败原因,但与挥发性盐基氮一样与腐败之间存在一定的相关性。     

应用渔业资源评估专家系统预测东海鲐年产量

利用渔业资源评估专家系统估算和预测了东海鲐年产量，实际的应用和对过去年产量的回顾预测都表明，该专家系统具有一定的实用性，其预测产量与实际产量比较接近，平均预测精度为87.8%，预测结果可供渔业生产和管理部门参考。从近十多年鲐的渔业生产和资源状况来看，鲐实际捕捞产量巳接近我们所评估的现存资源量。同时，渔获物的组成以当龄鱼为绝对多数，小型化、低龄化现象明显，说明东海鲐资源巳得到充分利用，并开始出现过度利用的迹象，资源前景并不乐观。     

Cold tolerance of the banana prawn Penaeus merguiensis de Man and its growth at different temperatures

Critical thermal minima (CTMin) were determined for subadults of Penaeus merguiensis acclimated at 15, 18, 21 and 24 °C for 3 weeks. The effect of cooling rate on CTMin was also investigated. The CTMin of prawns from these respective acclimation groups were 5.3, 6.0, 7.4, 9.0 and 4.7, 5.4, 6.0, 7.3 °C at the cooling rate of 1 °C h^?1 and 3 °C h^?1 respectively. Both acclimation temperature and cooling rate had a significant effect (P < 0.01) on the CTMin. Observation during the acclimation period showed that the growth rate of prawns acclimated at 24 °C was much higher than those acclimated at 21, 18 and 15 °C. The results indicate that P. merguiensis can overwinter in aquaculture ponds in south‐east Queensland, Australia, or other subtropical areas and attain good growth if simple overwintering facilities are available.     

乳山湾菲律宾蛤仔可溶性氮、磷排泄及其与温度的关系

菲律宾蛤仔(Ruditapes philippinarum)取自乳山湾东流区金港养殖区,其壳长范围为2.86~3.21 cm。实验结果表明,温度为20℃时,菲律宾蛤仔氮的排泄率最大(11.381μg.h-1.ind-1),是其他温度组(10℃、15℃、25℃、30℃)的2~8倍。菲律宾蛤仔代谢产物中NH4+-N占总无机氮的88%~91%,NO3--N和NO2--N占总无机氮的比例很小,分别为5.74%~7.89%和2.11%~4.01%,表明菲律宾蛤仔是排氨动物,氮的代谢终极产物主要为氨。磷的排泄随温度的变化不是很明显,排泄的磷中DOP的量明显小于DIP,总体趋势是随温度的升高略有增高,其中TDP和DIP变化幅度完全一致,DOP变幅相对较小,但上述3种形态P的水平随温度变化与N相比要小得多。通过实验分析表明,20℃时菲律宾蛤仔氮的排泄率最高。     

Growth and survival of the juvenile yellowleg shrimp Farfantepenaeus californiensis cohabiting with the green feather alga Caulerpa sertularioides at different temperatures

This study was performed to determine the growth and survival patterns of the juvenile yellowleg shrimp Farfantepenaeus californiensis cohabiting with the green feather alga Caulerpa sertularioides over a range of temperatures (18, 22, 25, 28 and 32°C) found throughout the year in the Gulf of California. From an initial weight of 46 ± 10 mg, shrimp cohabiting with green feather algae increased in weight by an average of 0.57 (±0.07), 5.44 (±0.45), 6.36 (±0.37), 7.66 (±0.26) and 5.96 (±0.59) g at 18, 22, 25, 28 and 32°C, respectively, whereas shrimp grown without seaweed increased in weight by an average of 0.28 (±0.026), 2.66 (±0.24), 3.15 (±0.49), 4.00 (±0.67), and 3.54 (±0.09) g respectively. Statistically significant differences were observed for the growth rates of juvenile yellowleg shrimp in the presence of C. sertularioides and peak growth was observed at 28°C in experiments with macroalgae. No significant differences were observed for shrimp survival except at 32°C without macroalgae, where survival was lower. These results suggest a beneficial and growth‐promoting effect of cohabitation with live C. sertularioides on F. californiensis.     

Growth of juvenile common snook (Centropomus undecimalis Bloch, 1792) reared at different temperatures and salinities: Morphometric parameters,RNA/DNA,and protein/DNA ratios

We investigated the growth of juvenile common snook (Centropomus undecimalis) reared at 25°C and 28°C and salinities of 0.3, 15, and 32 g L^?1. Total length, weight, RNA/DNA, and protein/DNA ratios were determined after 90 days of experiment. Higher growth was observed at 28ºC compared with 25°C, at the same salinity. At 28°C and 15 g L^?1 salinity, the weight (25.14 g) of juveniles was twice that of the juveniles reared at the lower temperature. At different salinities, only higher temperature affected growth, with higher weight values obtained at 15 g L^?1 in comparison with 0.3 and 32 g L^?1. Length was similar at 0.3 and 15 g L^?1. The RNA/DNA ratio was greater in juveniles reared at a salinity of 15 g L^?1 when compared with 0.3 and 32 g L^?1. This study shows that the combination of higher temperature and intermediate salinity promotes better growth of common snook juveniles.     

The growth and carbon allocation of abalone (Haliotis discus hannai) of different sizes at different temperatures based on the abalone‐kelp integrated multitrophic aquaculture model

The integration of shellfish and seaweed is an important and successful IMTA model. The IMTA of abalone and kelp has been well‐practiced in Sanggou Bay, China. In the present study, the growth and carbon allocation of abalone (Haliotis discus hannai) of different sizes (S, small; M, medium; L, large) fed kelp (Laminaria japonica) were investigated at different temperatures (10, 14, 18 and 22°C). A two‐way ANOVA showed that both size and temperature significantly affected the specific growth rate (SGR), food consumption (FC), feed conversion ratio (FCR) and apparent digestion rate (ADR) of abalone (p < 0.05), and significant interactions between the two factors were detected (p < 0.05). Curve estimation showed a significant quadratic relationship between SGR and temperature in each size class (p < 0.05). The two‐way ANOVA also showed that both size and temperature significantly affected all the measures of carbon allocation (p < 0.05) except for the carbon lost in metabolism (p > 0.05). All the measures of carbon allocation increased with the increasing temperature. It was concluded that it was better to culture H. discus hannai with a body weight less than 15 g at 20–22°C, and more than 15 g at 15–20°C to achieve good growth. The growth carbon of kelp around the abalone farm should be more than the metabolic carbon expenditure, which means the growth of kelp around the abalone farm should be more than 23.06%–61.91% of food consumption to maintain a carbon sink IMTA system without any carbon release.     

Macronutrient selection,absorption and energy budget of juveniles of the Australasian sea cucumber,Australostichopus mollis,feeding on mussel biodeposits at different temperatures

This study was set up to examine the selection and absorption of macronutrients (lipid, protein and carbohydrate) of juveniles of the Australasian sea cucumber Australostichopus mollis, feeding on an effective natural feed (mussel waste) at different temperatures. Our results indicate that the juveniles select and absorb lipid more efficiently than carbohydrate and protein at all temperatures. However, the overall magnitude of absorption of carbohydrate and protein make them the main source of nutritional energy for juvenile sea cucumbers. Seawater temperature affects the feeding behaviour of the juveniles, reducing the selection efficiency of macronutrients, while increasing metabolic energy demand, resulting in less energy available for growth. These results show the importance of each macronutrient in the diet of A. mollis as a source of energy for growth, which opens up the possibility to replace more expensive nutrient sources, such as protein and lipid, with less costly carbohydrate to reduce costs of diet formulation.     

马氏珠母贝黄壳色选系F1与对照组耗氧率和排氨率的比较

2006年4月,从流沙港马氏珠母贝养殖群体中挑选11个纯黄壳色个体为繁殖群体建立了黄壳色选系F₁。同时,随机选取了50个个体作为繁殖群体建立了对照组。2007年10月,从两个组分别选取相同规格的个体,比较了不同温度和盐度条件下两个组的耗氧率（OCR）和排氨率（NR）。结果表明：（1）在15~30 ℃,两个组的耗氧率和排氨率均随温度升高而增大。黄壳色选系的OCR和NR变化范围分别为0.117~1.009 mg / (g·h)和0.013~0.028 mg / (g·h),对照组的OCR和NR变化范围分别为0.142~0.827 mg / (g·h)和0.016~0.028 mg / (g·h)。（2）在15 ℃,对照组OCR和NR大于黄壳色选系,差异不显著（P>0.05）;在20、25和30 ℃条件下,黄壳色选系OCR和NR大于对照组,其中30 ℃时二者耗氧率差异显著（P<0.05）。（3）在15~30 ℃,黄壳色选系OCR和NR的Q₁₀平均值为4.87和1.91;对照组OCR和NR的Q₁₀平均值分别为3.54和1.46;两个组的氧氮比平均值分别为20.50和19.56。（4）在20~36盐度条件下,两个组的OCR和NR均随盐度增加而先上升再下降,在盐度28时出现最大值。黄壳色选系的OCR和NR变化范围分别为0.435~0.678 mg / (g·h)和0.011~0.027 mg / (g·h),对照组的OCR和NR变化范围分别为0.233~0.671 mg / (g·h)和0.014~0.025 mg / (g·h)。（5）在盐度20、24、28、32和36条件下,黄壳色选系耗氧率大于对照组,其中在盐度20、24和36时二者差异显著（P< 0.05）;在盐度28和32条件下,黄壳色选系排氨率大于对照组,在盐度20、24和36条件下,对照组的排氨率大于黄壳色选系,差异不显著（P> 0.05）。（6）在20~36盐度条件下,黄壳色选系和对照组的氧氮比平均值分别为34.50和25.01。研究结果表明经过一代壳色选育后黄壳色选系与对照组的生理指标存在明显差异,为马氏珠母贝的黄壳色系进一步选育提供依据。     

Abnormalities in the juvenile stage of sea bass (Dicentrarchus labrax L.) reared at different temperatures: types, prevalence and effect on growth

Osteological malformations are always considered an important problem in intensive aquaculture. This work studies the effect of rearing temperature on malformations in sea bass, Dicentrarchus labrax. To this end, two batches of the species were subjected to the following incubation/cultivation temperatures: 15 °C/natural and 19/19 °C, from fertilization until 190 days after hatching. The different malformations were studied in 1643 juveniles at 190 days and classified by categories. The Chi-square statistic was calculated to verify the relationship between the presence of anomalies and the application of different temperatures. The percentage of anomalies observed in individuals reared at a high temperature (19/19 °C) was 66.44%. In both temperature systems, opercular malformations were those which caused a greater delay in growth. The results found indicated that temperature played a very important role in the development of deformations, which may be of interest from the viewpoint of aquaculture.     

Pharmacokinetic–pharmacodynamic modelling for the determination of optimal dosing regimen of florfenicol in Nile tilapia (Oreochromis niloticus) at different water temperatures and antimicrobial susceptibility levels

Optimized dosing regimen is key to the effective use of antibacterials and to minimizing drug‐related side effects. The current study established a pharmacokinetic–pharmacodynamic (PK‐PD) model for the determination of optimal antibacterial dosing regimen in fish taken into consideration the temperature‐dependent PK and the pathogen‐dependent antimicrobial susceptibility, using florfenicol (FF) in Nile tilapia as an example. The calculated optimal dosages significantly varied by temperature and target MIC levels, ranging from 2.23 (MIC 1 µg/ml at 24°C) to 34.88 mg kg^?1 day^?1 (MIC 4 µg/ml at 32°C). The appropriateness of the calculated dosages was successfully verified by the in vivo studies. After 5 days of oral administration of the calculated optimal dosage at 24°C, the predicted plasma drug values were in line with the mean observed C_min(ss) while at 28 and 32°C underestimation of the C_min(ss) in a dose‐dependent manner was observed and likely due to the occurrence of non‐linear PK at high dosages. The averaged serum protein binding of FF was 19.1%. Our results demonstrated the appropriateness and clinical applicability of the developed PK‐PD approach for the determination of optimal dosing regimens at given temperatures and MICs. Saturation metabolism and PK non‐linearity of FF in tilapia warrant further study.     

Determination of the quality parameters of pike perch <Emphasis Type="Italic">Sander lucioperca</Emphasis> caught by gillnet,longline and harpoon in Turkey

ABSTRACT:   The effects of the different catching methods (gillnet, longline, harpoon) on sensory, chemical (pH, total volatile base nitrogen, K -value) and microbiological (total viable count [TVC]) changes in pike perch Sander lucioperca stored in ice were investigated. The same soaking time was used for both gillnet and longline fishing. The catching method had considerable influence on the freshness quality of pike perch. The acceptable shelf life was 15 days for pike perch caught by gillnet, and 22 days for longline and harpoon. The initial concentrations of inosine monophosphate (2.4 μmol/g) in pike perch caught by gillnet were significantly lower ( P  < 0.05) than longline (4.1 μmol/g), and especially by harpoon (16.7 μmol/g). However, the initial K -values for fish caught by harpoon were significantly ( P  < 0.05) lower (24.36%) than fish caught by longline and gillnet (57.69%, 64.41%, respectively). The average K , Ki, G and H -values at rejection day in terms of sensory assessment were approximately 90, 98, 156 and 40%, respectively, for all catching methods during ice storage. However, TVC reached 7.0 log cfu/g after approximately 11 days of storage for fish caught by gillnet, 19 days for fish caught by longline and 8 days for fish caught by harpoon. The result of this study suggests that the best catching method for preserving the freshness of pike perch is longline, based on the data obtained from the sensory and microbiological analysis.