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.     

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.     

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.     

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 gilthead sea bream from distinct production systems in Southern Europe: Intensive,integrated, semi-intensive or extensive systems

The quality of gilthead sea bream from distinct production systems and geographical locations in Southern Europe was evaluated to differentiate aquaculture products from extensive, integrated and semi-intensive systems from the ones produced intensively. This work analysed the external appearance of fish, yields after filleting as well as nutritional, sensory and histological characteristics of the muscle. The results showed that the yellow-golden line between eyes and the shiny red spot on the gill cover can be important and easy criteria to discriminate aquaculture products. Trimming losses are higher in fish from intensive systems. Lipid content of fish from extensive systems was significantly lower than values observed for fish reared intensively. Samples from the integrated and extensive systems showed the best n-3/n-6 ratio, contrarily to intensive systems, but it is difficult to establish clear quality markers to differentiate gilthead sea bream according to the rearing system. Regarding sensory characteristics, the sea bream flesh from intensive systems seems firmer and denser, having smaller white fibres and higher density of fibres in the dorsal muscle. The taste and odour of fatty fish was less strong in fish reared in non-intensive conditions, but extensive rearing in earthen pond is more propitious to the development of certain characteristics related to the environment.     

Rheological,physical and chemical characteristics of mulberry pekmez

The physical, chemical properties and the rheological behaviour of mulberry pekmez were investigated. Viscosity was measured at 30, 40, 50, 60 and 70 °C using a rotational viscometer equipped with spindle 5 at the speed of 5, 10, 20, 50 and 100 rpm. An empirical power-law model was used to describe the rheological behaviour of mulberry pekmez with correlation coefficients between 0.991 and 0.999. The mulberry pekmez exhibited a pseudoplastic behaviour. An Arrhenius equation was used to describe the effect of temperature on viscosity and E_a value of the mulberry pekmez was calculated as 17.97 kJ mol⁻¹.     

Seasonal variation in the chemical composition and microbiological condition of Mediterranean horse mackerel (Trachurus mediterraneus) muscle from the North Aegean Sea (Greece)

The aim of this work was to determine the chemical composition and microbiological quality of Mediterranean horse mackerel (Trachurus mediterraneus) muscle during the year and the consequent advantages or disadvantages in processing the raw material. A total of 180 samples were examined (15 samples per month) during two years (November 2001–November 2003). Fish were caught in the coastal waters of Chalkidiki peninsula (Northern Greece). Proximate composition of the muscle during the year resulted in: water 76.8 ± 1.39%, proteins 20.3 ± 0.68%, fat 1.3 ± 1.08% and ash 1.5 ± 0.08%. In March, April and May an increase in fat content of the muscle (2.5%, 2.8% and 2.1%, respectively) and a decrease in water content of the muscle (below 75.9%) were observed. On the contrary, fat content showed a decrease in September and October (0.4% and 0.6%, respectively), while water content of the muscle increased during these months (78.2% and 77.6%, respectively). The protein content of the muscle remained at high values, while the ash content was almost constant during the year. The mean value of muscle pH was 6.38 ± 0.16; extreme values (<6 or >7) of muscle pH were not observed. Total Viable Bacteria, Shewanella putrefaciens and Pseudomonas spp. were used as microbial indices to evaluate the microbiological quality of the muscle. Mean counts of Total Viable Bacteria, S. putrefaciens and Pseudomonas spp. during the year were: 4.01 ± 0.38 log₁₀ cfu/g, 2.37 ± 0.43 log₁₀ cfu/g and 3.34 ± 0.27 log₁₀ cfu/g, respectively. The variations of the values within seasons are minimal and significant homogeneity in the chemical composition and microbiological quality of Mediterranean horse mackerel muscle is observed. This is an important advantage in processing of the raw material.     

Comparison of microflora,chemical and sensory characteristics of artisanal Manchego cheeses from two dairies

It is widely accepted that cheeses, although manufactured according to the regulations of the Appellation of Origins, show important differences in the sensory attributes mainly due to the milk used (raw or pasteurised). This paper reports on comparison of changes in the microflora and chemical parameters related with proteolytic and lipolytic processes that occurred throughout eight months ripening in artisanal Manchego cheeses manufactured in two dairies. The results obtained indicate few chemical or microbiological differences between the cheeses from the two dairies; there were, however, differences in the proteolysis and lipolysis that gave rise to small but important sensory differences between cheeses from both dairies. Odour attributes contributed most to the differentiation of cheeses from both dairies.     

Effect of tea polyphenols on the physical and chemical characteristics of dried-seasoned squid (Dosidicus gigas) during storage

The effects of tea polyphenols (TP) dip treatment on the physical and chemical characteristics of dried-seasoned squid (Dosidicus gigas) during storage at 25 °C were assessed. After the storage, the b* value increased significantly, while the free amino acids (FAA) including Ser, Gly, Arg, Tyr and Lys, and the dominant reducing sugar (RS), lactose, decreased remarkably, which revealed the occurrence of browning reaction in dried-seasoned squid. The progressive conversion of trimethylamine oxide (TMAO) and production of thiobarbituric acid (TBA) and total volatile basic nitrogen (TVB-N) were found during the entire period of storage. Furthermore, the advantages of reducing moisture loss, inhibiting oxidation of lipids, depressing TMAO breakdown and TVB-N accumulation were observed, while the browning reaction exhibited no significant decrease for the TP samples. These results indicated that the addition of TP could maintain quality of dried-seasoned squid.     

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.     

南华北盆地谭庄凹陷巴1井原油地球化学特征及成藏条件

通过对南华北盆地谭庄凹陷巴1井下白垩统原油的地球化学特征分析,认为该原油来自于下白垩统烃源岩,为自生自储型油藏.结合埋藏史-热演化史模拟结果分析,推测该原油经历了至少早(K₁)、晚(N+Q)2期充注过程.油气成藏条件综合研究表明,谭庄凹陷下白垩统烃源岩品质较好、盖层封闭能力强、局部圈闭发育、匹配关系良好,但由于下白垩统砂岩为低孔低渗储层,物性整体差,制约了油气勘探的突破.建议开展高精度层序地层学研究和沉积相精细刻画,预测相对有利的储层砂体.     

渤海海域曹妃甸6-4油田原油物性差异分布特征及地质成因分析

利用大量原油物性分析化验资料,通过饱和烃色谱-质谱、芳香烃色谱-质谱等地球化学方法,结合流体包裹体、埋藏史-热史等成藏分析方法,对渤海海域曹妃甸6-4油田原油物性差异分布特征及地质成因进行了分析.结果 表明:①研究区原油物性差异分布主要表现为原油品质随着地层埋深的增加而逐渐变好,其中东三段和东二下段为轻质油藏,馆陶组为...     

四川盆地安岳特大型气田不同产能状态下龙王庙组的储层特征

下寒武统龙王庙组是安岳特大型气田的主力产气层,认识和刻画其储层特征对勘探开发至关重要。基于对安岳气田不同产能状态下龙王庙组储层的岩性、类型以及不同类型储层的厚度占比和孔洞发育情况的分析,建立高产井、中产井、低产井和干井中储层特征与油气产能的联系,其结果表明:龙王庙组储层主要发育于颗粒白云岩和结晶白云岩层段,储集空间有溶蚀孔洞、粒间溶孔、晶间溶孔和裂缝等,其中,孔洞和孔隙是主要类型;孔洞型储层是安岳气田中龙王庙组高产井的主导储层,其占比、孔洞发育密度、孔洞大小、孔洞段的单层厚度和累计厚度等是影响油气产能的主要因素;孔洞型储层的非均质性强,孔径呈双峰分布,表现为大尺寸(毫米级和微米级)的孔洞和小尺寸(纳米级)的晶间孔、晶间溶孔;孔隙型储层的孔隙分布均匀,孔径呈单峰分布,主要发育微米级孔隙。     

Effects of gamma irradiation and frozen storage on microbial,chemical and sensory quality of chicken meat in Iran

Irradiation is considered one of the most efficient technological processes for the reduction of microorganisms in food. It can be used to improve the safety of food products, and to extend their shelf lives. The aim of this study was to evaluate the effects of gamma irradiation and frozen storage as a combination process for improvement of chicken meat shelf life. Broiler chicken were treated with 0 (non irradiated), 0.75, 3.0, and 5.0 kGy of gamma irradiation and held frozen for 9 months. The control and irradiated samples were stored at −18 °C and underwent microbial analysis, chemical characteristics and sensory evaluation at 3 months intervals. Microbial analysis indicated that irradiation and freezing storage had a significant effect (P < 0.05) on the reduction of microbial loads. There was no significant difference in sensory quality and chemical characteristics during freezing storage in chicken meat. The combination of frozen storage plus irradiation resulted in greater overall reductions on microbial loads, extending shelf-life of chicken meat for commercial application and critical condition.     

神木-榆林地区马五_(1-2)亚段储层物性特征及岩溶作用的影响

研究区位于鄂尔多斯盆地东北部,马五_(1-2)亚段储层属于风化壳岩溶储层。通过钻井岩心、铸体薄片、扫描电镜、图像孔隙和阴极发光等分析测试手段的研究,发现该区马五_(1-2)储层发育10类典型孔隙,晶间孔、晶间溶孔、溶蚀孔洞的充填残余孔和非选择性溶孔是有效孔隙,硬石膏溶模孔和盐模孔的充填残余部分有效。统计大量的物性数据,认为马五_(1-2)储层属于特低孔渗储层;靖边气田岩溶储层的物性明显好于该区;马五1中自上而下小层孔隙度和渗透率有逐渐变小的趋势。δ~(18)O值的垂向变化表明,马五1中自上而下大气淡水的影响逐渐减弱,即同生期岩溶作用和表生期岩溶作用逐渐变弱,致使溶蚀孔洞的数量逐渐减少,物性向下变差。     

Effect of composition of tungsten(VI) and phosphorus(V) peroxoheteropoly derivatives on the efficiency of epoxidation of olefins under phase-transfer catalysis conditions

Epoxidation of hexene-1 and cyclohexene in the systems H₂WO₄/H₂O₂-H₂O/H₃PO₄ was studied under the phase-transfer catalysis conditions depending on the ratio between the reactants Na₂WO₄ and H₃PO₄ (in the presence of excess H₂O₂) and pH of the water phase. The interrelation between the pH of the aqueous phase, the composition of phosphatooxoperoxotungstate ions formed, and the catalytic activity of the systems was established. The complexes Q₃[PO₄{WO(O₂)₂}₄] and Q₂[HPO₄{WO(O₂)₂}₂], where Q⁺ is the lipophilic cation of a phase-transfer agent whose nature can have a noticeable effect on the composition of peroxoheteropoly compounds formed, exhibited the highest activity. To achieve the maximum catalytic activity, it is necessary to maintain the stoichiometric reactant ratio corresponding to the composition of peroxo complexes that prevail in a given pH range.     

Dissipation of propisochlor and residue analysis in rice,soil and water under field conditions

The analytical method for the residues of a new herbicide propisochlor and its dissipation and residual amounts in soil, water and rice plants in field conditions (rice cropping system) were studied. The chloroacetanilide herbicide, propisochlor (72% w/w EC) was applied at two dosages, 108 g a.i. ha⁻¹ (recommended) and 162 g a.i. ha⁻¹ (1.5 times of the recommended dosage) seven days after transplanting rice seedlings in the experimental fields in both Beijing and Fujian provinces (experimental localities). Soil, water and rice plant samples were collected at intervals and analyzed for propisochlor residues. The detection limit (LOD) of propisochlor is 0.2 μg kg⁻¹ and the limit of quantification (LOQ) was established as 1 μg kg⁻¹. At three different spiking levels, mean recoveries and relative standard deviation (RSD) from fortified samples in three replicated experiments for each matrix were in the range 81–109% and 1.3–13.1%, respectively. The results showed that the half-lives of propisochlor in water, soil and rice plant from Beijing were 0.56, 5.25 and 1.46 days respectively, and the half-lives of propisochlor in water, soil and rice plant from Fujian were 0.62, 5.12 and 0.81 days. At harvest, soil, straw, rice hull and husked rice samples were found to contain propisochlor well below the limit of detection (LOD) following the recommended dosage and 1.5 times dosage.