Effect of different concentrations of carbon dioxide and low concentration of carbon monoxide on the shelf-life of fresh pork sausages packaged in modified atmosphere

This paper reports the effects of different concentrations of carbon dioxide and the presence of low levels of carbon monoxide on quality attributes throughout storage of fresh pork sausages. Four pork forelegs (initial pH 5.5-5.7) were used to prepare a total of 120 fresh sausages, which were packaged in different atmospheres containing (%O(2)/%CO(2)/%N(2)): 0/20/80; 0/60/40; 40/20/40; 40/60/0; 80/20/0; and 0.3% CO/30% CO(2)/rest argon. The packs were stored for 20 days at 2±1 °C in the dark. Three packs for each atmosphere were opened every 4 days for subsequent analysis of pH, colour CIE L*, a*, b*, TBARS formation, microbial psychotrophic aerobes and sensory discolouration and off-odour. Results showed that increasing concentrations of carbon dioxide promoted oxidation of both myoglobin and lipids, most probably due to its effect of lowering pH. Therefore, preservation of colour and odour of fresh pork sausages packaged in modified atmosphere was better achieved using atmospheres containing low CO(2) concentrations (20%) rather than high (60%). However, their shelf-life depended also on the concentration of O(2); 20% CO(2) with high O(2) (80%) enhanced the red colour, but shortened shelf-life, while 20% CO(2) in the absence of O(2) extended freshness to 16 days. The atmosphere containing 0.3% CO, together with 30% CO(2), maintained the red colour for 20 days, but failed to keep fresh odour longer than 16 days.     

Evidence on correlation between number of disulfide bridge and toxicity of class IIa bacteriocins

The aim of this work was to study in the same microbiological conditions and for the first time the inhibitory action of eight class IIa bacteriocins against 23 Gram-positive bacteria in which some of them are industrially used as starters and against the eight class IIa bacteriocins producing strains themselves. The sensitivity of each strain was determined after MPA using the mathematical model described by Cabo et al. (1999, J. Appl. Microbiol. 87, 907-914). Therefore, the principal component analysis realized led to a strong correlation between spectrum and extra-disulfide bridge and a minor correlation between spectrum and isoelectric point of each bacteriocin.     

Characterisation of an antiviral pediocin-like bacteriocin produced by Enterococcus faecium

The bacteriocin-producing strain Enterococcus faecium ST5Ha was isolated from smoked salmon and identified by biomolecular techniques. Ent. faecium ST5Ha produces a pediocin-like bacteriocin with activity against several lactic acid bacteria, Listeria spp. and some other human and food pathogens, and remarkably against HSV-1 virus. Bacteriocin ST5Ha was produced at high levels in MRS broth at 30 °C and 37 °C, reaching a maximum production of 1.0 × 10⁹ AU/ml, checked against Listeria ivanovii ATCC19119 as target strain and surrogate of pathogenic strain Listeria monocytogenes. The molecular weight of bacteriocin ST5Ha was estimated to be 4.5 kDa according to tricine-SDS-PAGE data. Ent. faecium ST5Ha harbors a 1.044 kb chromosomal DNA fragment fitting in size to that of pediocin PA-1/AcH. In addition, the sequencing of bacteriocin ST5Ha gene indicated 99% of DNA homology to pediocin PA-1/AcH. The combined application of low levels (below MIC) of ciprofloxacin and bacteriocin ST5Ha resulted in a synergetic effect in the inhibition of target strain L. ivanovii ATCC19119. Bacteriocin ST5Ha displayed antiviral activity against HSV-1, an important human pathogen, with a selectivity index of 173. To the best of our knowledge, this is the first report on Ent. faecium as a potential producer of pediocin-like bacteriocin with antiviral activity.     

From SIR to SEAIRD: A novel data-driven modeling approach based on the Grey-box System Theory to predict the dynamics of COVID-19

Applied Intelligence - Common compartmental modeling for COVID-19 is based on a priori knowledge and numerous assumptions. Additionally, they do not systematically incorporate asymptomatic cases....     

Transport phenomena effect on the performance of proton exchange membrane fuel cell (PEMFC)

The aim of this work is to present a two-dimensional transient model, of heat and mass transfer in a proton exchange membrane fuel cell (PEMFC). The model includes various conservation equations such as mass (hydrogen, oxygen, water concentration), Momentum and energy equations this model is combined with the electrochemical model.     

One dimensional transient numerical study of the mass heat and charge transfer in a proton exchange membrane for PEMFC

The objective of our study is to quantify the mass water transferred by various modes: diffusion, convection and migration. For the water transfer, the principal forces considered in the model are, the convection force, the osmotic force (i.e. diffusion) and the electric force (migration). The first of these forces results from a pressure gradient, the second of a concentration gradient and the third of a protons' migration from the anode to the cathode, which has an effect on the dipole of the water molecules (resistance force to the advancement). The numerical tool used to solve the equations' system is the finite element method. The results obtained numerically considering this method are concentration profiles and concentration variation with time and membrane thickness. These results illustrate the contribution of each mass transfer mode.     

Hydroxyapatite growth on multiwall carbon nanotubes grown on titanium fibers from a titanium sheet

Nano-hydroxyapatite (HA) was grown on functionalized multiwalled carbon nanotubes (MWCNTs) deposited on TiO₂ nanofibers (NFs) that were hydrothermally grown on Ti metal sheets. The HA was electrochemically grown on the MWCNTs/TiO₂ porous layer. It was found that the HA grows on the MWCNTs/TiO₂ NFs in the form of dense coating with nanorice grain-shaped. The incorporation of MWCNTs between HA and TiO₂ NFs has led to higher adhesion strength as measured by micro-scratching test indicating the benefit of MWCNTs on the improving the bonding strength of HA layer. The obtained coatings exhibit excellent corrosion resistance in simulated body fluid. It is expected that this simple route for preparing the new HA/MWCNTs/TiO₂/Ti-layered structure might be used not only in the biomedical field, but also in catalysis and biological sensing among others.     

Markovian approach using several Gibbs energy for remote sensing images segmentation

The high resolution multispectral imagery needs to be segmented into regions that can be easily interpreted and which correspond roughly to the “ground truth”. In this paper, we segment multispectral images MSG2, provided by meteorological satellite “Meteosat Second Generation 2”, by using an approach based on support vector Markov model witch takes into account both the spectral and the spatial information. A multi-variable Gaussian distribution is used in image processing and the Gibbs energy is used to describe the process of labeling. There are several forms of Gibbs energy. We test the best known of them and evaluate the different results using the Borsotti function which is known to be more appropriate with our visual perception.