珍珠河蚌肉酶解制备ACE抑制肽研究

采用酸性蛋白酶、中性蛋白酶、碱性蛋白酶、木瓜蛋白酶、胃蛋白酶和胰蛋白酶水解珍珠河蚌肉,通过体外检测方法测定其ACE抑制率。结果表明,胃蛋白酶水解产物的ACE抑制率最大。采用四因素二次通用旋转设计对胃蛋白酶水解河蚌肉的水解条件进行优化,研究了酶与底物的质量比(E∶S)、温度、pH值和时间对水解产物ACE抑制率的影响,建立了回归方程,分析了各因素对ACE抑制率的影响,确定了最优的水解条件。     

河蚌肉的营养价值与加工研究进展

论述河蚌肉的营养价值和化学组成,重点阐述河蚌肉加工的国内外研究现状,指出我国河蚌肉制品研发过程中存在的主要问题,并对我国河蚌肉加工的发展前景进行预测和展望,以期为河蚌肉深加工及其新型制品的研发提供一定的参考。     

Electrodialysis Desalination and Reverse Osmosis Concentration of an Industrial Mussel Cooking Juice: Process Impact on Pollution Reduction and on Aroma Quality

ABSTRACT: An industrial mussel cooking juice was treated by a 3-step process to produce a natural aroma concentrate and a cleaned water stream. The juice was centrifuged before being desalinated by electrodialysis and then concentrated by reverse osmosis. As a result of this combined process, most of the physicochemical properties of the reverse osmosis permeate were reduced below the discharge standards. The concentrate was examined by a trained sensory panel (triangular tests, sensory profiles) and by gas chromatography/mass spectrometry. The sensory profile of the concentrate was shown as slightly different from the unprocessed mussel cooking juice one. Nevertheless, the concentration process preserved the native characteristic aroma of the cooked mussel, of interest to human or pet food industries.     

Assessment of mercury and methylmercury pollution with zebra mussel (Dreissena polymorpha) in the Ebro River (NE Spain) impacted by industrial hazardous dumps

Large amounts of industrial waste containing high concentrations of mercury (up to 436 microg/g) are dumped in a reservoir adjacent to a chlor-alkali plant in Flix (Catalonia, Spain), on the lower Ebro River. In order to assess the spatial redistribution of mercury from the point source and its bioavailability to the aquatic food web, zebra mussels (Dreissena polymorpha) were collected at several sites. The highest total Hg (THg) and methylmercury (MeHg) concentrations ever reported for zebra mussels were found (THg: 0.02 to 0.81 microg/g ww; MeHg: 0.22 to 0.60 microg/g ww). At the most polluted site, close to the waste dump, the mean values were 20 times greater than the local background level. Concentrations decreased with increasing mussel size at all sites. The MeHg/THg ratio was ca. 60% (range: 50-80%). A comparison of similar size classes clearly indicated the hot spots of Hg bioavailability to the aquatic food web and downstream transport.     

海水循环冷却技术研究

采用Langelier指数、Ryznar指数、Puckorius指数和StiffDavis稳定指数对某海水冷却水在不同p H值条件下的腐蚀与结垢倾向进行判断,考察了3种药剂的缓蚀阻垢性能,以及海水杀贝剂NKSW962对海水的杀生效果。结果表明,该海水具有结垢的趋势,且随其浓缩倍率和温度的升高,结垢的趋势加大。3种药剂对碳酸钙垢均有良好的抑制作用,适于在较低浓缩倍率条件下使用,采用加酸调节p H值的方法,可在较高的浓缩倍率条件下使用。钛、不锈钢和塑料等在不加药剂的海水系统即显示出优异的耐蚀性能。海水杀贝剂NKSW962对海水中的污损生物牡蛎、蓝贝和藤壶均有很好的杀灭效果。NHSW缓蚀阻垢剂与非氧化性杀贝剂NKSW960具有很好的配伍稳定性。     

Marine mussel adhesion: biochemistry,mechanisms, and biomimetics

Common blue mussel (Mytilus edulis) is a sessile organism that has unique ability to attach to a wide array of organic and inorganic marine surfaces using its holdfast structures. Strong adhesion to surfaces is essential for mussel survival, movement, and self-defense. Mussel proteins from byssal thread are structural components connecting soft mussel tissues to marine surfaces via an adhesive plaque in the distal end, while adhesive proteins from byssal plaque are responsible for mussel adhesion. Adhesive proteins are small molecules containing a high proportion of post-translationally modified amino acids such as 3,4-dihydroxyphenylalanine (DOPA). High DOPA content, small molecular size, protein flexibility, the presence of metal ions, and a high oxidation state enable strong mussel adhesion to surfaces. Mussel adhesion mechanisms depend on the composition and interactions of mussel proteins, as well as their interactions with the environment. Difficulties in the extraction of mussel adhesion proteins hamper mechanism studies and their practical applications. Development of recombinant mussel proteins and biomimetics will advance our understanding of adhesion mechanisms. In this paper, recent advances in the characterization of mussel adhesive proteins (MAPs), mussel adhesion mechanisms, application of MAPs, and the development of biomimetic biopolymers are reviewed.     

贻贝煮汁酶解液美拉德反应条件优化及其产物氨基酸组成分析

为提高对贻贝副产物的利用,以木瓜蛋白酶水解贻贝煮汁得到的酶解液为原料,经联合脱腥后进行美拉德反应,以感官评价及褐变程度为指标,研究影响贻贝煮汁酶解液美拉德反应呈味效果的各因素,并通过单因素试验及响应面试验设计优化工艺条件,以获得氨基酸态氮含量高且色泽风味好的产物。结果表明：响应面优化的美拉德反应最佳工艺条件为还原糖添加量3.3%、氨基酸添加量3.1%、加热时间55 min、初始pH 8.0,经高效液相色谱测定,贻贝煮汁液和美拉德反应产物中均检测出17 种氨基酸,在最优条件下的美拉德反应产物中,总氨基酸及必需氨基酸含量与煮汁液相比,分别增加了315.91%和428.84%。可见,经美拉德反应后的产物在营养和风味上均优于贻贝煮汁液,是研制新型贻贝调味品的理想原料。     

The Contribution of DOPA to Substrate-Peptide Adhesion and Internal Cohesion of Mussel-Inspired Synthetic Peptide Films

Mussels use a variety of 3, 4-dihydroxyphenyl-l-alanine (DOPA) rich proteins specifically tailored to adhering to wet surfaces. Synthetic polypeptide analogues of adhesive mussel foot proteins (specifically mfp-3) are used to study the role of DOPA in adhesion. The mussel-inspired peptide is a random copolymer of DOPA and N(5) -(2-hydroxyethyl)-l-glutamine synthesized with DOPA concentrations of 0-27 mol% and molecular weights of 5.9-7.1 kDa. Thin films (3-5 nm thick) of the mussel-inspired peptide are used in the surface forces apparatus (SFA) to measure the force-distance profiles and adhesion and cohesion energies of the films in an acetate buffer. The adhesion energies of the mussel-inspired peptide films to mica and TiO(2) surfaces increase with DOPA concentration. The adhesion energy to mica is 0.09 μJ m(-2) mol(DOPA) (-1) and does not depend on contact time or load. The adhesion energy to TiO(2) is 0.29 μJ m(-2) mol(DOPA) (-1) for short contact times and increases to 0.51 μJ m(-2) mol(DOPA) (-1) for contact times >60 min in a way suggestive of a phase transition within the film. Oxidation of DOPA to the quinone form, either by addition of periodate or by increasing the pH, increases the thickness and reduces the cohesion of the films. Adding thiol containing polymers between the oxidized films recovers some of the cohesion strength. Comparison of the mussel-inspired peptide films to previous studies on mfp-3 thin films show that the strong adhesion and cohesion in mfp-3 films can be attributed to DOPA groups favorably oriented within or at the interface of these films.     

Characteristics of a refuge for native freshwater mussels (Bivalvia: Unionidae) in Lake St. Clair

The Lake St. Clair delta (∼ 100 km²) provides an important refuge for native freshwater mussels (Unionidae) wherein 22 of the ∼ 35 historical species co-occur with invasive dreissenids. A total of 1875 live unionids representing 22 species were found during snorkeling surveys of 32 shallow (∼ 1 m) sites throughout the delta. Richness and density of unionids and zebra mussel infestation rates varied among sites from 3 to 13 unionid species, 0.02 to 0.12 unionids/m², and < 1 to 35 zebra mussels/unionid, respectively. Zebra mussel infestation of unionids in the delta appears to be mitigated by dominant offshore currents, which limit densities of zebra mussel veligers in nearshore compared to offshore waters (13,600 vs. 28,000/m³, respectively). Glycogen concentrations in the tissues of a common and widespread species in the delta (Lampsilis siliquoidea) suggest that zebra mussels may be adversely affecting physiological condition of unionids in a portion of the Lake St. Clair delta. Physiological condition and community structure of unionids within the delta may also be influenced by differences in food quantity and quality resulting from the uneven distribution of water flowing from the St. Clair River. The delta likely supports the largest living unionid community in the lower Great Lakes and includes several species that have been listed as Endangered or Threatened in Canada and/or the state of Michigan, making it an important refuge for the conservation of native unionids.