Microbiological,chemical and sensory changes of whole and filleted Mediterranean aquacultured sea bass (Dicentrarchus labrax) stored in ice

The effect of filleting on the microbiological, chemical and sensory properties of aquacultured sea bass (Dicentrarchus labrax) stored in ice was studied. Pseudomonads, H₂S‐producing bacteria (including Shewanella putrefaciens) and Brochothrix thermosphacta were the dominant bacteria at the end of the 16 day storage period in ice for both whole ungutted and filleted sea bass. Enterobacteriaceae were also found in the spoilage microflora of whole ungutted and filleted sea bass, but their counts were always lower than those of pseudomonads, H₂S‐producing bacteria (including S putrefaciens) and B thermosphacta. Total viable counts for whole ungutted sea bass were always lower than those for filleted sea bass samples. Of the chemical indicators of spoilage, TMA (trimethylamine) values of whole ungutted sea bass increased very slowly, whereas significantly higher values were obtained for filleted samples, with respective values of 0.253 and 1.515 mg N per 100 g muscle being reached at the end of their shelf‐life (days 13 and 9 respectively). TVB‐N (total volatile basic nitrogen) values showed a slight increase for whole ungutted sea bass during storage, reaching a value of 26.77 mg N per 100 g muscle (day 13), whereas for filleted fish a corresponding value of 26.88 mg N per 100 g muscle was recorded (day 9). TBA (thiobarbituric acid) values increased slowly for whole ungutted and filleted sea bass samples throughout the entire storage period, reaching final values of 4.48 (day 13) and 13.84 (day 9) mg malonaldehyde kg^?1 respectively. Sensory assessment of raw fish using the EC freshness scale gave a grade E for up to 5 days for whole ungutted sea bass, a grade A for a further 4 days and a grade B for an additional 4 days, after which sea bass was graded as C (unfit). Overall acceptability scores for odour, taste and texture of cooked whole ungutted and filleted sea bass decreased with increasing time of storage. The results of this study indicate that the shelf‐life of sea bass stored in ice, as determined by overall acceptability sensory scores and microbiological data, is 8–9 days for filleted and 12–13 days for whole ungutted fish. Copyright © 2003 Society of Chemical Industry     

Substrate Specificity of the Highly Thermostable Esterase EstDZ3

Esterases are among the most studied enzymes, and their applications expand into several branches of industrial biotechnology. Yet, despite the fact that information on their substrate specificity is crucial for selecting or designing the best fitted biocatalyst for the desired application, it cannot be predicted from their amino acid sequence. In this work, we studied the substrate scope of the newly discovered hydrolytic extremozyme, EstDZ3, against a library of esters with variable carbon chain lengths in an effort to understand the crucial amino acids for the substrate selectivity of this enzyme. EstDZ3 appears to be active against a wide range of esters with high selectivity towards medium- to long-carbon chain vinyl esters. In-silico studies of its 3D structure revealed that the selectivity might arise from the mainly hydrophobic nature of the active site's environment.     

Directed evolution on the cold adapted properties of TAB5 alkaline phosphatase

Psychrophilic alkaline phosphatase (AP) from the Antarctic strain TAB5 was subjected to directed evolution in order to identify the key residues steering the enzyme's cold-adapted activity and stability. A round of random mutagenesis and further recombination yielded three thermostable and six thermolabile variants of the TAB5 AP. All of the isolated variants were characterised by their residual activity after heat treatment, Michaelis-Menten kinetics, activation energy and microcalorimetric parameters of unfolding. In addition, they were modelled into the structure of the TAB5 AP. Mutations which affected the cold-adapted properties of the enzyme were all located close to the active site. The destabilised variants H135E and H135E/G149D had 2- and 3-fold higher kcat, respectively, than the wild-type enzyme. Wild-type AP has a complex heat-induced unfolding pattern while the mutated enzymes loose local unfolding transitions and have large shifts of the Tm values. Comparison of the wild-type and mutated TAB5 APs demonstrates that there is a delicate balance between the enzyme activity and stability and that it is possible to improve the activity and thermostability simultaneously as demonstrated in the case of the H135E/G149D variant compared to H135E.     

Development of an urban health and wellbeing index for work precincts: A comparative study in Sydney,Australia

Work precincts are recognized for their significant role as generators of employment and associated commerce within urban areas. This study describes a method for analyzing the physical characteristics of urban work precincts in promoting the health and wellbeing of their occupants. The following physical parameters are analyzed: public transport accessibility, green and blue spaces, food environments, fitness facilities, supermarkets, and grocery stores. The parameters are assessed using quantitative spatial analysis based on street network data, as well as point of interest data acquired from OpenStreetMap (OSM). The streets and their intersections are stored in the OSM database as links and nodes, respectively. The evaluation of the performance metrics involves measuring the street network distance from each node to the closest node of interest for each parameter. The metrics are then combined, forming an urban health and wellbeing index (UHWI), which can be used to compare the performance of different precincts. The method was tested by investigating four work precincts in Sydney, Australia, all hosting a large office building belonging to the same business institution. Our results identified two of the four precincts with a high UHWI and resulted in the identification of one underperforming precinct.     

Where does the money go? Economic flow analysis of construction projects

A new approach is introduced for analysing the economic flows in a construction project that will complement the existing methods. The main focus of the new method is to trace the flow of costs in the project and identify their spatial characteristics as well as who are the final recipients. This type of analysis highlights the flow of costs of the specific project in the local economy. It can be used for decision-making purposes from the project-commissioning party. Costs were divided into six categories, namely: labour, materials, energy, office overheads, taxes and personnel, and into two levels: local and national. Three case studies of stone and reinforced concrete structures were selected and analysed to test the application of this method. The case studies showed that this method and the representation by a Sankey diagram can provide useful insights regarding both the spatialized distribution of the cost of a project and the economic flows going to direct labour versus overhead and taxes. For future projects, local authorities or developers can select the most economically suitable strategy maximizing the income of the local community.     

Assessment of pesticide residues in fresh peach samples produced under integrated crop management in an agricultural region of northern Greece

A multi-residue method using selected ion monitoring mode GC/MS has been developed for the quantitative analysis of residue levels of 23 widely used pesticides in fresh peaches produced under integrated crop management process (ICM). The proposed methodology involved a sample extraction procedure using liquid–liquid partition with acetonitrile followed by a clean-up step based on solid-phase extraction (SPE). Fortification studies were performed at different concentration levels for various types of peaches that differ in properties, such as appearance, flavor and pit. The data showed that the different peach matrices had no significant effect on recoveries. Recoveries were greater than 80% for most of the pesticides with a RSD below 18%. The limits of quantification (LOQs) were in the range 0.002–0.050 mg kg^?1, depending on the compound. To assess method performance with real samples and determine whether pesticide concentrations in peaches exceed their maximum residue levels (MRLs), the proposed method was successfully applied to the analysis of 104 fruit samples collected under integrated pest management (IPM) production during the 2006 cultivation period. Residues detected were lower than those established by legislation for all pesticides, except diazinon, where one positive sample was detected at a level of 0.03 mg kg^?1.     

Transfer, attachment, and formation of biofilms by Escherichia coli O157:H7 on meat-contact surface materials

Studies examined the effects of meat-contact material types, inoculation substrate, presence of air at the liquid-solid surface interface during incubation, and incubation substrate on the attachment/transfer and subsequent biofilm formation by Escherichia coli O157:H7 on beef carcass fabrication surface materials. Materials studied as 2 × 5 cm coupons included stainless steel, acetal, polypropylene, and high-density polyethylene. A 6-strain rifampicin-resistant E. coli O157:H7 composite was used to inoculate (6 log CFU/mL, g, or cm(2)) tryptic soy broth (TSB), beef fat/lean tissue homogenate (FLH), conveyor belt-runoff fluids, ground beef, or beef fat. Coupons of each material were submerged (4 °C, 30 min) in the inoculated fluids or ground beef, or placed between 2 pieces of inoculated beef fat with pressure (20 kg) applied. Attachment/transfer of the pathogen was surface material and substrate dependent, although beef fat appeared to negate differences among surface materials. Beef fat was the most effective (P < 0.05) inoculation substrate, followed by ground beef, FLH, and TSB. Incubation (15 °C, 16 d) of beef fat-inoculated coupons in a beef fat homogenate (pH 4.21) allowed the pathogen to survive and grow on coupon surfaces, with maximal biofilm formation observed between 2 and 8 d of storage and when air was present at the liquid-solid interface. The results indicated that the process of fabricating beef carcasses may be conducive to the attachment of E. coli O157:H7 onto meat-contact surfaces and subsequent biofilm formation. Furthermore, it is recommended that substrates found in beef fabrication settings, rather than laboratory culture media, be used in studies designed to investigate E. coli O157:H7 biofilm development and control in these environments. PRACTICAL APPLICATION: Findings of this study provide knowledge on the effect of type of beef carcass fabrication surface material, fabrication-floor fluids and residues, and incubation conditions on attachment/transfer and subsequent biofilm formation by E. coli O157:H7. The results highlight the importance of thoroughly cleaning soiled surfaces to remove all remnants of beef fat or other organic material that may harbor or protect microbial contaminants during otherwise lethal antimicrobial interventions.     

New soluble porphyrin bearing a pyridinylethynyl group as donor for bulk heterojunction solar cells

Bulk heterojunction solar cells were fabricated using the blend films of a porphyrin bearing pyridinylethynyl group (POR) as electron donor and PC₆₀BM or PC₇₀BM as electron acceptor. Photoluminescence measurement of the blend films of POR with fullerene derivatives indicated that charge transfer was possible between POR and fullerene derivatives. The solution processed bulk heterojunction solar cells using the blend of POR with PC₆₀BM and PC₇₀BM exhibit overall power conversion efficiency (PCE) of 1.96% and 2.54%, respectively. The PCE of the BHJ solar cell has been further improved up to 3.27% when thermally annealed POR:PC₇₀BM was used as active layer, which is attributed mainly to the increase in short circuit current. The increase in J_sc is attributed to the enhanced crystallinity of the blend (particularly POR) and efficient π-electron conjugation of POR, resulting to an improvement in hole mobility, leading to more balance charge transport. The PCE of the device based on as cast POR:PC₇₀BM has been further improved up to 4.06% when DMF treated PEDOT:PSS buffer layer was used.     

Grip to the Colon by Means of Macroscopic Adhesion-Controlled Friction

Manipulating friction without applying high normal forces is important for an intestine inspection and intervention device in order to eliminate the risk of tissue damage. One possible solution is to generate friction by means of adhesive forces. The adhesive forces should be high to offer sufficient grip without needing high normal forces. The generated friction is then called adhesion-controlled and depends on the size of the area in contact. Adhesion-controlled friction is well known to be dominant at microscopic and molecular levels. According to this paper, adhesion-controlled friction can be applicable on the macroscopic scale as well and, more specifically, within a range of forces in which friction is usually considered to be load-controlled. The intestine inspection and intervention device manipulates the friction with the colonic wall by means of mucoadhesive films. In this way, grip with high static friction is achieved without the need to apply high normal forces and friction is altered by changing the size of the area of the mucoadhesive film. Friction theories on different scales are revisited and considered in order to understand the dominant phenomena and the principles associated with this macroscopic adhesion-controlled friction.