Seasonal variation of physical,chemical and sensory characteristics of sea bream (Sparus aurata) reared under intensive conditions in Southern Europe

This study describes the variability of important quality traits in gilthead sea bream produced under intensive conditions in Southern Europe and purchased in a French market (Nantes). Chemical, sensory and histological characteristics were performed on 18 samples delivered over a year. All fish presented far lower dioxin and DL-PCBs or heavy metals concentrations than the maximum limit level set by EC Regulation, being totally safe for human consumption. Fat content and nutritional values reflected by n-3 and n-6 polyunsaturated fatty acids (PUFA) levels were parameters with high variability according to the season or the fish farm. Values of n-3 PUFA ranged from 0.9% to 8.6% and those of n-6 PUFA from 9.3% to 16.6%, corresponding to a respective variation of n-3/n-6 ratio between 0.1 and 0.6. Increased fat levels in flesh lead to a more intense odour, a fatty fish flavour and a whiter appearance of the cooked fillet. Flesh total amino acid composition was rather stable whereas the small differences detected on firmness by the sensory panel were weakly related to histological characteristics. Rearing techniques of the farm seems to modulate the major characteristics of the fish.     

Effect of mechanical separation process on lipid oxidation in European aquacultured sea bass,gilthead sea bream,and rainbow trout products

Mechanical separation systems are a good option to create new fish products and open new market, however studies on the effect on quality of mechanical treatment on species of interest for European aquaculture, such as European sea bass, gilthead sea bream, and rainbow trout are scarce. Thus in this research, the effect on colour, nutritional quality, and lipid stability was considered immediately after separation process and after 90 days of frozen storage. Results revealed that mechanical separation technique significantly affected colour and lipid stability of the three studied species. Increases in L* and secondary oxidation products were observed, together with a decrease of antioxidant capacity. Nutritional value instead was unaffected by treatment. Thus, mechanical separation process could represent a new way to better exploit species of interest for European aquaculture and acquire new market niches, but oxidative processes during the treatment have to be limited and kept under control.     

Comparison of perfluoroalkyl substances contamination in farmed and wild-caught European sea bass (Dicentrarchus labrax)

Perfluoroalkyl substances (PFASs) are a family of persistent pollutants of anthropic origin which can reach humans mainly through diet, causing potentially dangerous effects on health. Fish and fishery products are a major source of exposure, but intra- and inter-specific contamination can be extremely variable. In the present study a single species monitoring of the presence of perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA), the two main compounds of the family, was performed on 140 farmed and wild caught European sea basses (Dicentrarchus labrax) from different places in the Mediterranean area. The results highlight a strong correlation between the level of contamination and the origin of fishes, if wild or farmed: on average, wild caught sea basses (PFOS: 112-12,405 ng/kg, median 1345 ng/kg; PFOA: 9–487 ng/kg, median 28 ng/kg) showed higher levels than intensively farmed sea basses (PFOS: 11–105 ng/kg, median 32 ng/kg; PFOA: 9–51 ng/kg, median 21 ng/kg). Significant differences among the various rearing systems were also observed, with extensively-farmed subjects presenting relatively higher levels of both compounds compared to intensively farmed. Moreover, a certain variability among wild fish caught from different sampling sites was observed, confirming that PFASs contamination, which reached in some cases noticeable concentrations, might be influenced by the geographical origin.     

Disposition of 14C-flumequine in sea bream (Sparus auratus) after single intraperitoneal administration

This study was conducted to evaluate the pharmacokinetics of flumequine following intraperitoneal administration of ¹⁴C-Flumequine (12 mg/kg, 100 μCi/kg) in sea bream (Sparus auratus). Three fish (147 ± 29 g) were collected at various time points ranging from 0.5 h to 144 h post administration. Absorption, distribution and elimination were studied using whole body autoradiography and liquid scintillation counting whereupon the concentration of flumequine equivalent versus time was evaluated in major organs and tissues (liver, bile, heart, brain, blood, kidney, intestine, spleen, red and white muscle). An agreement between the data obtained from whole body autoradiography and liquid scintillation counting was observed. A rapid and extensive distribution of flumequine to the major organs 0.5 h after dosing was recorded. The main route of elimination appeared to be biliary excretion due to the high concentration of radioactivity in the bile and the prolonged elimination phase compared to others tissues. The elimination of flumequine from the blood followed a two compartmental model with half life of the first phase and second phase being 0.98 h and 21.4 h respectively. The maximum flumequine recorded in blood (C_max) was 9.09 mg/kg at 0.78 h (T_max). Only traces of drugs were observed in the major tissues of the fish 72 h after administration. Based on the current results and the elimination in edible tissues in particular, flumequine seems to be an excellent treatment candidate for sea bream.     

Quality differences of whole ungutted sea bream (Sparus aurata) and sea bass (Dicentrarchus labrax) while stored in ice

The aim of this study is to determine the quality changes in whole ungutted sea bass and sea bream while stored in ice. Changes in chemical quality were determined by using pH, total volatile basic nitrogen (TVB-N, mg N/100 g), trimethylamine (TMA-N, mg/100 g), thiobarbituric acid (TBA, mg malonaldehyde/kg), water activity (a_w), color measurement, and sensory analysis. Changes in microbiological quality were determined by using the analysis of total viable mesophilic and psychrophilic bacterial counts. Result of this study indicated that the shelf life of sea bass and sea bream stored in ice as determined by overall acceptability sensory scores and microbiological data was 15 days.     

Use of impedance spectroscopy for predicting freshness of sea bream (Sparus aurata)

In the present study, the use of a rapid portable system based on impedance spectroscopy to assess fish freshness has been tested. The evolution of different physical and chemical parameters (moisture, fat, pH and TVBN) and impedance measurements (modulus and phase at different frequencies) of six different batches of sea bream (Sparus aurata) were analysed. Impedance spectroscopy was able to classify raw matter into six groups according to composition differences, and also to classify those samples stored for a time of between 0 and 15 days into different groups according to degree of freshness. TVB-N is one of the most usual parameters to assess shelf life periods of fish samples; the coefficient of determination (R²) of 0.72 obtained in the Partial Least Squares regression for this parameter confirmed the potential application of the impedance spectroscopy for predicting sea bream freshness.     

Multiresidue determination of antibiotics in feed and fish samples for food safety evaluation. Comparison of immunoassay vs LC-MS-MS

Antibiotic residues (sulfonamides and tetracyclines) were determined in Gilthead sea bream (Sparus aurata) and feed samples by means of immunoassays and LC-MS-MS (liquid chromatography-mass spectrometry²). A preliminary study to know the withdrawal time of oxytetracycline in Gilthead sea bream samples was also conducted. It was carried out using immunoassays based on photometric detection of horseradish peroxidase (HRP) activity and time-resolved fluorometric detection of coproporphyrin of Platinum (II) (ELISA and TR-FIA, respectively). The results were compared to those obtained using an LC-MS-MS methodology. They showed that approximately 37 days would be the withdrawal time in order not to exceed the MRL and fish could be commercialized with safety.Regarding feed samples analysis, an LC-MS-MS method was optimized including sample treatment. Average recoveries (n = 6) ranging from 78 to 108% were obtained and precision of the method was between 0.2 and 3%. The same sample treatment was applied to the feed immunoanalysis obtaining satisfactory results.Finally, 20 fish and 4 feed samples were analysed in order to confirm the feasibility of the immunoassays for detecting antibiotic residues. Sulfonamide residues were not detected in any fish sample. Tetracycline residues were detected in some fish samples from marine farms, with total concentrations between 2.1 and 152 ng g^?1. In all cases, the obtained results correlated well with those achieved by LC-MS-MS. Therefore, the new methodology allows for food safety of the medicated fish.     

Effect of sodium alginate-based edible coating containing different anti-oxidants on quality and shelf life of refrigerated bream (Megalobrama amblycephala)

The effect of alginate-based edible coating containing Vitamin C (Vc) and tea polyphenols (TP) for shelf-life extension of bream (Megalobrama amblycephala) was evaluated over a 21-day storage at refrigerated temperature (4 ± 1 °C). Bream were left untreated (CK), or were treated with alginate–calcium coating (T1), alginate–calcium coating incorporating 5% Vc (T2), or alginate–calcium coating incorporating 0.3% TP (T3). The fish samples were analyzed periodically for water loss, microbiological (total viable count), chemical (pH, total volatile basic nitrogen (TVB-N), thiobarbituric acid (TBA), K-value) and sensory characteristics. The results indicated that coating treatments retarded the decay of fish compared to uncoated bream. T2 more efficiently inhibited the growth of total viable counts than did T1 or T3 (p < 0.05). Coating treatments predominantly reduced chemical spoilage, reflected in TVB-N, pH, and TBA, retarded water loss (p < 0.05) and increased the overall sensory quality of fish compared to uncoated bream.     

Exploring high hydrostatic pressure for enhancing the preservation of white and dark muscle fish fillets stored at different packaging systems under refrigeration

High hydrostatic pressure (HHP) is an old preservation method. However, there is still a gap in the literature about their promising conditions for improving the shelf life and quality of different fish groups (dark and white muscle) at different packaging systems (air and vacuum) stored under refrigeration. Since it is crucial to boost optimization research and enable HHP industrial commercialization, this study aimed to identify promising high hydrostatic pressure (HHP) conditions to extend the maximum fresh fish quality of dark and white muscle fillets stored under air-packing and vacuum-packing (DM-AP, DM-VP, WM-AP, and WM-VP, respectively), considering the bacteriological (total viable aerobic count), physicochemical (lipid oxidation, lightness, redness, yellowness, total color changes, and hardness or firmness), and sensory (appearance, color, odor, texture, and acceptability) characteristics during refrigerated storage. The systematic literature search was carried out in four databases (PubMed, Science Direct, Scopus, and Web of Science) to retrieve articles from 2001 to 2023 published in English. A total of 3,922 articles were retrieved, of which 49 were eligible for systematic review and 47 for meta-analysis. Overall, the best HHP conditions for DM-AP (400 MPa/5 min/5 °C) and DM-VP (400 MPa/5 min/20 °C) extended the microbial and sensory shelf life from about 6 to ≥ 9 days with a positive effect on color (ΔE ≤ 4). Concerning WM-AP, HHP at 220 MPa/10 min/25 °C and 250 MPa/5 min/3 °C did not affect lipid oxidation and extended the sensory acceptability by 2–4 days but negatively influenced hardness and color (ΔE > 5). For WM-VP, HHP at 300 MPa/3 or 10 min/10–20 °C could prolong the microbial and sensory shelf life by 7 days without affecting hardness, decreased lipid oxidation, and color changes (ΔE < 4). Therefore, HHP may enable the shelf life extension of dark and white muscle fish fillets stored under refrigeration in aerobiosis and vacuum while retaining their quality.     

Levels of polychlorinated dibenzo-p-dioxins,dibenzo-p-furans and polychlorinated biphenyls in farmed sea bass (Dicentrarchus labrax) and sea bream (Sparus aurata) from Turkey

Farmed European sea bass and Gilthead sea bream were obtained from four different fish farms in Turkey during 2008–2009, for determination of 17 2,3,7,8-Cl-substituted PCDDs and PCDFs, and coplanar and indicator PCBs.Concentrations of ∑PCDD/Fs and DL-PCBs, as TEQ, in fish samples, ranged from 0.14 to 0.70 pg TEQ₍₁₉₉₈₎ g⁻¹ wet weight and from 0.46 to 4.51 pg TEQ₍₁₉₉₈₎ g⁻¹ wet weight, respectively. The concentrations of total indicator PCBs in fish samples ranged from 3.1 ng g⁻¹ to 22.1 ng g⁻¹ wet weight. Concentrations of PCDD/Fs and DL-PCBs were below the EU regulation (EC No. 1881/2006) limits.     

Assessment of mercury level in commonly consumed marine fishes in Malaysia

Twelve species of common marine fish consumed by Malaysians were collected from local wholesale market in Malaysia; the mercury concentrations in muscle and liver samples were determined by cold vapour atomic absorption spectrophotometry. The mercury concentration in the samples, expressed in μg g⁻¹ dry weight. It was 0.45 for short-bodied mackerel, 0.04 for scad, 0.04 for narrow-bodied Spanish mackerel, 0.13 for black pomfret, 0.50 for long tail tuna, 0.03 for greasy grouper, 0.09 for chacunda gizzard shad, 0.06 for yellow-banded scad, 0.05 for eastern little tuna, 0.09 for delagoa treadfish bream, 0.10 for giant perch and 0.00 for sardine’s muscle tissue. Among the fishes analyzed, long tail tuna had the highest level followed by short-bodied mackerel. Significantly lower levels (P < 0.05) of mercury were found in liver tissues. Total mercury concentration in liver tissues were as follow; 0.03 for short-bodied mackerel, 0.02 for scad, 0.05 for narrow-bodied Spanish mackerel, 0.10 for black pomfret, 0.49 for long tail tuna, 0.03 for greasy grouper, 0.03 for chacunda gizzard shad, 0.04 for yellow-banded scad, 0.02 for eastern little tuna, 0.09 for delagoa treadfish bream, 0.01 for giant perch and 0.01 for sardine. This study indicates that commonly consumed fish from Malaysia have concentrations of mercury below the permissible levels stated in the US FDA guidelines.     

Concentration of Cd (II), Cu (II), Pb (II), Se (IV) and Zn (II) in cultured sea bass (Dicentrarchus labrax) tissues from Tyrrhenian Sea and Sicilian Sea by derivative stripping potentiometry

The purpose of this study is to investigate the bioaccumulation of trace metals (Zn, Cu, Se, Cd, and Pb) in cultured Dicentrarchus labrax tissues, liver and muscle, from the Sicilian coasts of Mediterranean sea. The relationship between heavy metals contamination of feed and seawater and their bioaccumulation in fish tissues was also studied. Potentiometric stripping analysis (PSA) was used to determine simultaneously the content of Cd (II), Cu (II), Pb (II) and Zn (II), in fish tissues, feed and sea water, whereas selenium concentration was determined by cathodic stripping potentiometry (CSP). Metal cations were extracted from fish tissues, commercial feed and sea water (for total metal determination) by peroxide hydrogen/hydrochloric acid treatments; seawater did not need any sample pre-treatment for dissolved metals determination. The low concentration of metals in the studied matrices required a highly sensitive method for their determination and a simple sample preparation procedure, and the proposed method was well-suited for this purpose.     

The effects of tangerine peel (Citri reticulatae pericarpium) essential oils as glazing layer on freshness preservation of bream (Megalobrama amblycephala) during superchilling storage

This work was aim to the application of tangerine peel essential oils (TPEOs) as glazing layer on fish preservation. In this paper, essential oils were respectively extracted from the peel of ponkan, bitter orange and sweet orange. Their compositions were analyzed using GC–MS method. Fresh sample of bream was immersed into different TPEO for the formation of glazing layers on the surface and stored at −1 ±0.2 °C for 25-days storage. A thorough study of freshness evaluation was carried out and statistics analysis was performed to analyze the effect of TPEO. The result showed that the glazing layers of TPEO can effectively slow down the degradation process of fish samples and the resulting variations in electrical, moisture, chemical, microbial, sensory and textural characteristics. Additionally, statistical analysis showed that there are significant (most of p is less than 0.05) difference between control and treated sample, but insignificant (most of p is more than 0.05) differences among the samples with glazing layer of different TPEOs.The work indicated TPEOs had remarkable effect in the storage of aquatic products.     

塔里木盆地满西区块强制海退体系域沉积模式

构造运动、全球海平面变化和气候的相互作用控制了沉积物供给量以及可容空间被充填的规模.在强制海退情况下的缓坡边缘上,相对海平面下降期间过路沉积物未被输送到盆底,而被沉积为一组逐级下降的前积楔,形成强制海退体系域.塔里木盆地满西区块的东河砂岩等时段是基于东河砂岩段上部和下部所存在的层序界面(不整合面)而划分的,具有等时性,但岩性、岩相在不同位置、不同地区会有变化.东河砂岩等时段所属的层序SQ1的层序界面是海平面长期下降的结果,并受到构造运动的加强作用,表现为一个盆地范围内广泛发育的不整合面.层序SQ1的发育演化明显受到海平面变化的控制:在海平面快速上升时期发育海侵体系域;在海平面缓慢下降时期发育强制海退体系域.满西地区的东河砂岩是强制海退体系域的沉积产物,是在海退背景下发育的复合砂体,其展布非常复杂,多数呈点状或块状展布.层序SQ1的油气储集体主要分布于海岸带附近,它们是前滨—临滨沉积砂体.     

珠江口盆地晚渐新世陆架边缘三角洲沉积层序结构及演化

南海北部上渐新统珠海组广泛发育外陆架-陆架边缘三角洲和深水斜坡扇体系，它们构成了区内最为重要的油气储层。综合地震、测井、岩心等资料，研究了珠海组陆架边缘三角洲及前三角洲斜坡扇的层序结构、沉积成因类型、沉积演化及控制作用。珠海组为一个复合层序，其内可进一步分为4个层序。通过追踪坡折点变化建立了滨岸迁移轨迹，划分了各层序内的沉积成因单元（水进、略上行正常水退、明显上行正常水退、局部下行强制性水退等）。外陆架三角洲以发育厚约100~150 m的前积层为特征，地震上多表现为切线型反射结构；而陆架边缘三角洲前缘-斜坡复合前积层厚达200~1 000 m，具S型、切线斜交型等地震反射结构，以发育厚层的三角洲前缘砂坝和大规模的滑塌变形堆积为特征，并与前三角洲-斜坡扇共生。研究区可识别出6套三角洲前积体，其面积具有逐渐变大、并沿走向扩展的趋势。区内晚渐新世层序的发育受到海平面变化的控制，区域性沉积旋回还受到构造沉降作用叠加的影响。大量沉积物的供给和区域性海平面下降是导致陆架边缘三角洲和前三角洲斜坡扇广泛发育的主控因素。     

比较与借鉴：英美社会保障机制

建立和完善有效的社会保障机制，是我国深化国有企业改革，实现两人根本转变的关键一环，通过对英美两国的社会保障机制的比较研究，吸附其成功经验，对于我国在市场经济条件下构客完善社会保障机制，兼顾公平与效率原则，防止遭遇英国式的“高福利”病和避免美国式的“贫富度悬殊”症，是一个有益的借鉴。     

西非下刚果—刚果扇盆地A区块中新统深水水道体系沉积特征及演化

深水水道体系沉积演化特征及其控制因素研究是揭示大陆边缘"源—汇"过程和取得深水油气勘探突破的关键.下刚果—刚果扇盆地中新统发育有大型深水水道沉积,基于A区块的地震、测井、岩心等资料,利用地震属性分析等手段,阐述了中新统层序地层格架内深水水道体系的沉积特征、演化规律并讨论了其控制因素.区内中新统可划分为4个三级层序(SQ...     

Occurrence of Vibrio spp. in sea fish, shrimps and bivalve molluscs harvested from Adriatic sea

One hundred and seventeen samples of sea fish (100), shrimps (10) and bivalve molluscs (7) were sampled at fish markets (100 samples) and hotels (17 samples) along the sea side in Croatia within the period from May to July 2000. The samples were tested for the presence of Vibrio spp. Vibrio spp. was isolated in 23 (19.65%) of total count of samples. The most frequently found were V. parahaemolyticus (9.40%), V. vulnificus (6.84%) and V. alginolyticus (3.42%). A significantly larger number of positive findings involved the samples collected at hotels (35.29%) as compared to those collected at fish markets (17.00%). The isolation was conducted by a conventional cultivation with the enrichment in alkaline peptone water and on TCBS Kobayashi agar (“Biolife”).     

Effect of Anisakis simplex (sl) larvae on the spoilage rate and shelf-life of fish mince products under laboratory conditions

Wild caught marine fish are commonly infected with anisakid nematodes lodging in the intestinal linings or in the fish muscle. One of the most commonly found nematode parasites in marine fish is Anisakis simplex. During production of mince from the muscle of wild caught Anisakis-infected fish, the larvae would be disrupted during mince production. Any bacteria within or on the surface of such larvae are during the mincing process evenly distributed throughout the mince, and could thus possibly affect the spoilage rate of the final products. To explore if or how any bacteria associated with muscle-invading Anisakis larvae may affect the spoilage rate of fish mince, a controlled storage trial was conducted. Fillets of farmed Atlantic cod (Gadus morhua), exclusively fed on dried and heat-treated compound feed and hence expectably free from Anisakis larvae, were aseptically collected and homogenised. Fish mince aliquots were added different volumes of Anisakis homogenate based on larvae which were freshly sampled from the visceral cavity of NE Atlantic blue whiting (Micromesistius poutassou). The volumes of added parasite homogenate (parasite(+)-samples) reflected different infection intensities from 15 (low) to 50 (high) larvae per 100 g fish fillet, representing an actual Anisakis intensity range in the flesh of blue whiting. The samples were kept at 4 °C for 15 days and subjected to microbiological, sensory and chemical evaluation at 3 days intervals. Upon visual examination and plate count measurements (PC) on Iron Agar Lyngby (IAL), the samples without any parasite additives (no[parasite]) spoiled differently and more rapidly than any of the parasite(+)-samples. However, H₂S-producing bacteria were only recorded in the latter samples, which were also the only ones that showed increased levels of the spoilage indicator substance trimethylamine (TMA). Moreover, the parasite(+)-samples changed their sensory characteristics at a later stage compared to the no[parasite]-samples. Although some cultures of H₂S-producing bacteria were found on IAL, molecular identification by PCR-DGGE of the actual bacteria was not conclusive. Psychrobacter sp. which has no or only little spoilage activity, was identified in all samples until trial day 9, but was probably outgrown by the stronger spoilers Pseudomonas fluorescence/fragi and Photobacterium phosphoreum. Thus, and somewhat unexpected, our findings indicate that – under the present trial conditions – fish mince contaminated with bacteria which originate from Anisakis larvae, spoiled less rapidly than samples without any parasite-related bacteria present. Moreover, the shelf-life of fish mince was apparently not reduced by the presence of bacteria transferred to the mince by Anisakis larvae.     

渤海海域古近系、新近系原油富集/贫化控制因素与成藏模式

渤海海域油气勘探经历了40多年的曲折历程,原油垂向分布规律及控制因素的复杂性制约了其勘探进程。基于断裂活动、烃源岩演化与区域盖层的研究,对全区已发现油藏的垂向富集规律及其控制因素进行了深入的分析。结果表明,(晚期)新构造运动对原油成藏与分布起到主导作用。通源断裂垂向输导原油的能力与其活动速率有关,活动速率小于10m/Ma的断裂输导能力弱,主要起封闭作用;活动速率为10~25m/Ma的断裂起到输导与封闭双重作用;活动速率大于25m/Ma的断裂主要起输导作用。晚期断裂活动速率、活跃生油岩与区域性盖层的发育分布及其时空配置关系,共同控制了古近系、新近系原油的富集与贫化。并归纳了渤海海域古近系、新近系4种原油富集/贫化模式,即古近系富集模式、古近系与新近系共同富集模式、新近系富集与古近系贫化模式以及新近系贫化模式。