Kinetics of tropomyosin denaturation as a predictive model for verifying thermal processing of beef products

An enzyme-linked immunosorbent assay (ELISA) was developed to study thermal denaturation of tropomyosin (Tm) using the time-temperature requirements for cooked beef. The ELISA employed a monoclonal antibody (MAb 2C9) raised against bovine Tm for quantifying residual Tm in muscle extracts. The specificity of MAb 2C9 to bovine Tm was demonstrated by Western blot and the analytical validity of ELISA was confirmed by dot blot. Thermal denaturation of Tm, in the temperature range between 54.4 and 70.0 degrees C, showed first-order dependency. Kinetic parameters of Tm denaturation were derived from isothermal heating of beef muscle extract at 54.4, 57.2, 60.0, and 62.8 degrees C. Temperature dependency of the rate constant (k) was demonstrated by Arrhenius plot; the activation energy (E(a)) of Tm denaturation was determined to be 484 kJ x mol(-1). A mathematic model describing the impact of the heating time-temperature on Tm denaturation was developed. Predicted Tm from the integrated time-temperature model agreed closely with the measured Tm in dynamically heat-processed beef samples. Percent errors between the measured and the predicted values ranged from -5.1 to 5.3%. The kinetic model provides an accurate and reproducible prediction of the impact of actual heating time-temperature on residual Tm in cooked beef. The MAb-based ELISA and kinetic model developed in this study have the potential to be adapted by the meat industry as a quality control tool.     

Characterization of some yeasts isolated from foods by traditional and molecular tests

In this study, 22 yeast strains isolated from foods were characterized by traditional and molecular techniques. With the help of traditional identification tests, yeast strains were grouped in 12 species belonging to 11 genera as follows: Candida parapsilosis, Rhodotorula mucilaginosa, Debaryomyces hansenii, Cryptococcus humicolus, Cryptococcus albidus, Aureobasidium spp., Hanseniaspora valbyensis, Metschnikowia pulcherrima, Lachancea thermotolerans, Pichia anomala, Geotrichum candidum and Yarrowia lipolytica. The patterns obtained by the digestion of ITS-18S rRNA gene with MspI and HaeIII restriction endonucleases were similar among strains belonging to the same species. With the help of randomly amplified polymorphic DNA (RAPD) analysis performed within the same species, discrimination of M. pulcherrima strains could be achieved.     

Analysis of the survival of <Emphasis Type="Italic">Listeria monocytogenes</Emphasis> in food-grade lubricants

Listeria monocytogenes is a ubiquitously occurring Gram-positive bacterium, which is associated with raw ready-to-eat foods, in particular with smoked or graved salmon. Due to its tenacity and psychrotrophic growth properties, it may persist on the equipment and machinery used in food production. In this study, we analysed the survival of three L. monocytogenes strains in eight H1 lubricants, seven greases and one oil, applicable for food-processing machinery. None of the native lubricants contained Listeria spp. above the detection limit of 10³ cfu/g. In artificially contaminated lubricants, the viable counts of different L. monocytogenes strains decreased by more than 99.9% within 7 days, and the reduction rates were found to dependent on the composition of the respective lubricant as well as on the L. monocytogenes strain. Chemical binding of either benzoate or acetate to native grease 3 caused a similar anti-listerial activity, but a decreased effect was observed when stearic acid was used. When benzoate, acetate, salicylate or parabene was added at a concentration of 0.5% to native grease 1, similar anti-listerial effects were observed. The water content (0, 1 and 5%) and the age of the lubricant did not influence the results. Used lubricants originating from dismantled industrial machinery did not contain L. monocytogenes, though this microorganism was re-isolated from the lubricants following artificial contamination. Thus, there is no evidence that L. monocytogenes replicate or persist in the H1 lubricants used in this study.     

Aerosol synthesis of cargo-filled graphene nanosacks

Water microdroplets containing graphene oxide and a second solute are shown to spontaneously segregate into sack-cargo nanostructures upon drying. Analytical modeling and molecular dynamics suggest the sacks form when slow-diffusing graphene oxide preferentially accumulates and adsorbs at the receding air-water interface, followed by capillary collapse. Cargo-filled graphene nanosacks can be nanomanufactured by a simple, continuous, scalable process and are promising for many applications where nanoscale materials should be isolated from the environment or biological tissue.     

International Migration for Work-Consequences for the Families Who Remain at Home (The Case of Romania)

This paper analyses the consequences of international migration for work on families who remain at home in a Romanian rural sample. Five types of effects were identified: financial; on spousal relations; on children; on old family members and on composition of the population. The most important are the financial impacts, but there are also invisible side-effects, such as deterioration in the relations between spouses and the decrease of the parents?? roles for children. The importance of the old family members is re-evaluated; they are key social links between migrants and the family members that have remained at home.     

Drivers of water governance reforms in the Philippines

This paper analyses the enabling conditions for a water governance model responsive to future Philippine water requirements. Using the stage-based approach to institutional reforms, it assesses the outcomes of previous water governance reforms, such as conflicts in customary and formal rules; urban and rural; upstream and downstream; and the contestations in water supply privatization in Metro Manila. The analysis suggests that past water governance reforms were symbolic and procedural, and structural changes to support the legal frameworks were not achieved. Based on the case findings, the authors support the current reform agenda of implementing a decentralized framework of water governance at a watershed scale.     

Characterizing local water governance structure in the Philippines: results of the water managers’ 2013 survey

This paper provides an empirical basis for local water-governance reforms in the Philippines using primary data from 299 water managers representing water districts, community-based water organizations, irrigators’ associations and local government water providers. Survey results showed that local water organizations are subject to various forms of laws and regulations; there are no set bases for water price determination; and water administration set-up varies from the formal to the loosely informal structures. Recommendations are offered towards responsive local water governance arrangements.     

On solving permutation scheduling problems with ant colony optimization

A new approach for solving permutation scheduling problems with ant colony optimization (ACO) is proposed in this paper. The approach assumes that no precedence constraints between the jobs have to be fulfilled. It is tested with an ACO algorithm for the single-machine total weighted deviation problem. In the new approach the ants allocate the places in the schedule not sequentially, as in the standard approach, but in random order. This leads to a better utilization of the pheromone information. It is shown by experiments that adequate combinations between the standard approach which can profit from list scheduling heuristics and the new approach perform particularly well.