HYDROCARBON POLLUTION ALONG MOROCCAN COASTS AND BPH ACTIVITY IN THE MUSSEL PERNA PERNA

Specimens of the mussel Perna perna were collected along Moroccan coasts to determine the concentrations of polycyclic aromatic hydrocarbons (PAHs) bioaccumulated in the tissues, and to measure benzo[a]pyrene hydroxylase (BPH) activity. Chemical analysis of PAHs show that the Mediterranean (Nador, Martil, Tanger) and central Atlantic coasts (from Rabat to Jorf Lihoudi) are those most contaminated (351 245 ng.g^{? 1} dry weight in Tanger). The mussel contaminants were of mixed origin for most of the locations with non negligible inputs of petrogenic origin in many of them. Baseline levels of PAHs were between 6 and 55 ng.g^{? 1} dry weight. BPH activity showed significant correlation (r _s = 0.64, P < 0.05) with total PAH concentrations at the six most contaminated stations. The baseline level of BPH activity can be identified as in the range 0.1 to 13 pmol.min^{? 1}.mg prot^{? 1} along the Mediterranean and Atlantic coasts.     

Changes in quality characteristics during cold storage of shucked mussels (Mytilus galloprovincialis) and selected chemical decomposition indicators

The following chemical changes were observed during the cold storage of mussels for 6 days at 4 °C. Total volatile basic nitrogen (TVB‐N, mg N per 100 g) and trimethylamine values (TMA‐N, mg N per 100 g) were increased from 22.55 and 5.96 mg per 100 g at day 0 to 12.38 and 0.42 mg per 100 g, respectively, at the end of the storage period. The indole value and putrescine concentration were increased from 15.36 µg kg^?1 and 24.7mg kg^?1 to 34.46 µg kg^?1 and 63.86 mg kg^?1, respectively, on the fourth day of storage. The pH was slightly reduced and tyramine and cadaverine were not detected during storage. TVB‐N, TMA‐N and indole value could be selected as decomposition indicators for mussels during their cold storage. Acceptable limits of 15 mg per 100 g for TVB‐N, 3 mg per 100 g for TMA‐N, 35 µg kg^?1 for indole and 60 mg kg^?1 for putrescine are suggested. Sensory and chemical results indicated that the shelf‐life of mussels at 4 °C is limited to 4 days. Copyright © 2005 Society of Chemical Industry     

Seasonal changes in phospholipids of mussel (Mytilus edulis Linne)

The phospholipids of mussels (Mytilus edulis Linne) from the coast of Qingdao were extracted, fractionated and analysed over a 12 month period. The contents of total lipids, neutral lipids, polar lipids and phospholipids were measured. The composition of phospholipids was determined by high‐performance liquid chromatography, and their fatty acid composition was analysed by gas chromatography. The phospholipid content ranged from 3.6 to 6.4 g kg^?1 soft tissue. PE (phosphatidyl ethanolamine) and PC (phosphatidyl choline) were the major constituents. C16:0, C20:5 and C22:6 were the major fatty acids. C20:5 (5.25–23.10%) and C22:6 (6.05–20.42%) varied regularly with the seasonal factors. Their total amounts were high from January to June, which would be an optimal time for the utilisation of the phospholipids of mussels. © 2002 Society of Chemical Industry     

Long-term trends of Lake Michigan benthos with emphasis on the southern basin

Lake Michigan benthic macrofauna have been studied for almost a century, allowing for a unique analysis of long-term changes in community structure. We examined changes in abundances of three major taxonomic groups of benthic macroinvertebrates (Diporeia, Oligochaeta, and Sphaeriidae) in southern Lake Michigan from 1931 to 2015 and identified the most likely causes for these changes. Abundances of all three groups increased during 1931–1980 with the bulk of these increases occurring in nearshore (≤50 m) waters and coincident with increased loading of phosphorus (P) and subsequent increased primary production. Abundances of all three taxa declined during 1980–2000 again mostly in nearshore waters and coincident with decreased P loading. The quagga mussel (Dreissena rostriformis bugensis) invasion was associated with a further decline in phytoplankton primary production during 2000–2015. Both Diporeia and Sphaeriidae declined in abundance during that time, with Diporeia exhibiting the more pronounced decrease of the two groups. In contrast, Oligochaeta increased in abundance during 2000–2015. The quagga mussel has become, by far, the most abundant benthic macroinvertebrate species in terms of density and biomass. Overall, the primary driver of changes in the abundances of the three major taxa during this 85-year period appeared to be changes in phytoplankton primary production due to changing P loadings and, later in the time series, Dreissena filtering. The dreissenid mussels invasions coincided with a rapid decline of Diporeia abundance, but the mechanism of this negative effect remains unidentified. In contrast, Oligochaeta likely benefited from the quagga mussel invasion, perhaps via quagga-generated food supply.     

Effect of turmeric and lemongrass essential oils and their mixture on quality changes of refrigerated green mussel (Perna viridis)

Effect of turmeric and lemongrass essential oils (Eos) and their mixture on quality of green mussel stored at 4 °C was investigated. The mixture of 0.25% turmeric and 0.25% lemongrass Eos could lower microbiological and chemical deterioration of mussel as evidenced by the lower microbial counts, total volatile base, ammonia, trichloroacetic acid‐soluble peptide contents and thiobarbituric acid‐reactive substances, compared with the control (P < 0.05). It indicated that a mixture of turmeric and lemongrass Eos in mussel showed synergistic effect on the retardation of bacterial growth and lipid oxidation. However, samples treated with 0.5% lemongrass oil exhibited the higher likeness score for odour and flavour, compared with the samples treated with other Eos throughout the storage of 15 days. Samples treated with turmeric essential oil caused the changes in odour and flavour. Therefore, lemongrass treatment was shown to be the promising means to prevent the deterioration and maintain the odour and flavour attributes of mussel during prolonged refrigerated storage.     

Utilization of waste freshwater mussel shell as an economic catalyst for biodiesel production

An economic and environmentally friendly catalyst derived from waste freshwater mussel shell (FMS) was prepared by a calcination-impregnation-activation method, and it was applied in transesterification of Chinese tallow oil. The as-prepared catalyst exhibits a “honeycomb” -like structure with a specific surface area of 23.2 m² g⁻¹. The newly formed CaO crystals are major active phase of the catalyst. The optimal calcination and activity temperature are 900 °C and 600 °C, respectively. When the reaction is carried out at 70 °C with a methanol/oil molar ratio of 12:1, a catalyst concentration of 5% and a reaction time of 1.5 h, the FMS-catalyst is active for 7 reaction cycles, with the biodiesel yield above 90%. The experimental results indicate that the FMS can be used as an economic catalyst for the biodiesel production.     

响应曲面法优化紫贻贝酶解液制备海鲜风味基料

以紫贻贝酶解液为原料,采用感官评价和GC-MS分析的方法研究Maillard反应制备海鲜风味基料的最佳工艺条件及产物的挥发性风味成分。结果表明：Maillard反应制备海鲜风味基料的最优模式体系为丙氨酸与脯氨酸的添加质量分数为0.5%、质量比为2:3、葡萄糖与木糖的总添加量为8%、质量比为1:3、反应pH6.2,反应温度为100℃、反应时间为25min;上述条件下制得的海鲜风味基料经GC-MS分析,鉴定出29种挥发性化合物,主要有羧酸类、吡嗪类、酯类、醛类、酮类、醇类、含硫类等化合物,对海鲜风味有贡献的化合物主要有苯并噻唑、3-甲硫基丙醛、吡嗪类等化合物。     

基于人工神经网络法优化河蚌多糖超高压提取工艺

以取珠后的蚌肉为原料,采用超高压方法提取河蚌多糖。利用响应面试验设计获取神经网络所需的训练样本,利用训练成熟的神经网络进行训练和仿真,分析因素(压力强度、料液比和保压时间)以及因素间的交互作用对河蚌多糖得率的影响,并对超高压得河蚌多糖的工艺进行优化。结果表明:人工神经网络法比响应面法的优化准确性高,预测值的可信度较强;超高压提取河蚌多糖最佳工艺条件为:压力强度340 MPa、料液比1:42(g/mL)、保压时间10 min,该条件下的多糖得率预测值为7.18%,实测值为7.12%,相对误差为0.84。该工艺具有短时、高效、环保等优点,为河蚌多糖的开发利用提供技术依据。     

煅烧紫贻贝壳粉对Cd2+和Pb2+的吸附热力学研究

贻贝是我国的重要的海产经济贝类,但由于养殖规模的增大而随之产生的废弃贻贝壳资源成为了关注的热点。研究发现贻贝壳是一种环境友好型的生物吸附剂,本文通过高温煅烧处理,进一步优化了贻贝壳的吸附性能,采用SEM、BET、XRD和IR表征手段对贻贝壳的微结构、孔径及组成进行了分析;同时探讨了贝壳粉吸附剂对Cd2+和Pb2+的吸附热力学性能。结果发现贻贝壳粉经高温煅烧后,其主要成分为CaO,且比表面积显著增大,比表面积达7.8965 m2/g,形成诸多纳米孔径,直径在0.5~1.1 nm,吸附性能提高。贻贝壳吸附剂用量和溶液pH对Cd2+和Pb2+的吸附量影响较大,吸附剂对Cd2+的吸附量明显高于对Pb2+的吸附量,且吸附剂对Cd2+和Pb2+的吸附均符合Freundlich等温吸附模型。由此可知,煅烧后的紫贻贝壳是一种优良廉价的生物吸附剂,可将其开发成一种针对性去除废水中重金属Cd2+的新型吸附剂。     

基于高通量测序的紫贻贝中微生物群落分析

为探究不同状态下紫贻贝制品表面附着的微生物菌群组成情况。本实验以新鲜紫贻贝、冻藏紫贻贝、自制紫贻贝干,贮藏自制紫贻贝干和市售紫贻贝干为研究对象,通过对紫贻贝表面附着微生物提取及高通量测序分析,获得不同紫贻贝样品中微生物组成及变化情况。实验结果表明,各样本中有效序列范围为30066～40563条、Operational taxonomic unit(OTU)范围为28～128,其中市售紫贻贝干OTU数最低,而冻藏紫贻贝OTU数相对较高;新鲜紫贻贝和自制紫贻贝干中主要是嗜冷杆菌属和不动杆菌属,冻藏紫贻贝干中主要为嗜冷杆菌属,贮藏紫贻贝干中主要为假单胞菌属和嗜甲基菌属,而市售紫贻贝干中优势菌群为葡萄球菌属和肠球菌属。不同状态下的紫贻贝样品的菌群组成均存在着较大距离,表明紫贻贝状态、加工过程及贮藏销售环境等,均对贻贝产品菌群组成产生较大的影响。研究结果可为保障紫贻贝制品的质量与安全提供参考。