Search results for "Colony Count"
showing 10 items of 131 documents
Thermal inactivation kinetics of Bacillus stearothermophilus spores using a linear temperature program.
1999
A systematic study of the inactivation kinetics of Bacillus stearothermophilus spores was carried out in nonisothermic heating conditions using a linear temperature increase program and analyzing the experimental data by means of a one-step nonlinear regression. The D and z values estimated are close to those obtained in isothermic conditions and estimated by using a two-step model, first D values are calculated, and then in the second step a z value is deduced (D(121 degrees C) = 3.08 and 4.38 min, respectively, and z = 7 and 7.9 degrees C, respectively). No convergence problems were observed when using the one-step nonlinear regression proposed. The results indicated that the methodology …
High gas pressure: An innovative method for the inactivation of dried bacterial spores
2012
In this article, an original non-thermal process to inactivate dehydrated bacterial spores is described. The use of gases such as nitrogen or argon as transmission media under high isostatic pressure led to an inactivation of over 2 logs CFU/g of Bacillus subtilis spores at 430 MPa, room temperature, for a 1 min treatment. A major requirement for the effectiveness of the process resided in the highly dehydrated state of the spores. Only a water activity below 0.3 led to substantial inactivation. The solubility of the gas in the lipid components of the spore and its diffusion properties was essential to inactivation. The main phenomenon involved seems to be the sorption of the gas under pres…
Characterization of antimicrobial properties on the growth of S. aureus of novel renewable blends of gliadins and chitosan of interest in food packag…
2007
The biocide properties of chitosan-based materials have been known for many years. However, typical antimicrobial formulations of chitosan, mostly chitosonium salts, are known to be very water sensitive materials which may impair their use in many application fields such as food packaging or food coating applications. This first work reports on the development and characterization of the antimicrobial properties of novel fully renewable blends of chitosan with more water-resistant gliadin proteins isolated from wheat gluten. Chitosan release to the nutrient broth from a wide range of blends was studied making use of the ninhydrin method. The results indicated that both pure chitosan and its…
Origanum vulgare subsp. hirtum Essential Oil Prevented Biofilm formation and showed antibacterial activity against planktonic and sessile bacterial c…
2013
Essential oils from six different populations of Origanum vulgare subsp. hirtum were compared for their antibiofilm properties. The six essential oils (A to F) were characterized by a combination of gas chromatography with flame ionization detector and gas chromatography with mass spectrometer detector analyses. All oils showed weak activity against the planktonic form of a group of Staphylococcus aureus strains and against a Pseudomonas aeruginosa ATCC 15442 reference strain. The ability to inhibit biofilm formation was investigated at sub-MIC levels of 200, 100, and 50 m g/ml by staining sessile cells with safranin. Sample E showed the highest average effectiveness against all tested stra…
Prevalence of bacteria and absence of anisakid parasites in raw and prepared fish and seafood dishes in Spanish restaurants
2015
This study evaluated the presence of bacteria and anisakid parasites in 45 samples of raw anchovies in vinegar, a dish widely eaten in Spain, and in 227 samples of cooked fish and cephalopods served in Spanish food service establishments. Our analysis showed that, according to European and Spanish regulation, 14 to 30% of the prepared fish and cephalopod dishes exceeded the maximum allowable level for mesophilic aerobic counts, and 10 to 40% of these samples exceeded the allowable levels for Enterobacteriaceae. None of the studied samples showed evidence of anisakid parasites, Escherichia coli, Staphylococcus aureus, Salmonella, or Listeria monocyto genes. These results indicate that applic…
Photoactivated chlorophyllin-based gelatin films and coatings to prevent microbial contamination of food products
2008
[EN] The aim of this work was to develop antimicrobial photosensitizer-containing edible films and coatings based on gelatin as the polymer matrix. incorporating sodium magnesium chlorophyllin (E-140) and sodium copper chlorophyllin (E-141). Chlorophyllins were incorporated into the gelatin film-forming solution and the inhibiting effect of the cast films was tested against Staphylococcus aureus and Listeria monocytogenes. The results demonstrated that water soluble sodium magnesium chlorophyllin and water soluble sodium copper chlorophyllin reduced the growth of S. aureus and L monocytogenes by 5 log and 4 log respectively. Subsequently, the activity of self-standing films and coatings con…
A Silicone Ventricular Catheter Coated with a Combination of Rifampin and Trimethoprim for the Prevention of Catheter-related Infections
1998
So-called antiinfective catheters which are generated by incorporation of antimicrobial substances into polymers appear to be effectful devices in the prevention of catheter related infections. Such devices mainly act by prevention of bacterial colonization of the catheter surface rather than by inhibition of adherence. In a preceding study, we developed a rifampin-containing silicone catheter for the prevention of ventricular shunt infection. In the present study, this work was continued with a combination of antimicrobials incorporated in silicone ventricular catheters to reduce the risk of rifampin resistance and to expand the antimicrobial spectrum. We found that the drug release kineti…
Animal rennets as sources of dairy lactic acid bacteria
2014
ABSTRACT The microbial composition of artisan and industrial animal rennet pastes was studied by using both culture-dependent and -independent approaches. Pyrosequencing targeting the 16S rRNA gene allowed to identify 361 operational taxonomic units (OTUs) to the genus/species level. Among lactic acid bacteria (LAB), Streptococcus thermophilus and some lactobacilli, mainly Lactobacillus crispatus and Lactobacillus reuteri , were the most abundant species, with differences among the samples. Twelve groups of microorganisms were targeted by viable plate counts revealing a dominance of mesophilic cocci. All rennets were able to acidify ultrahigh-temperature-processed (UHT) milk as shown by pH …
Characterisation and detection of spoilage mould responsible for black spot in dry-cured fermented sausages.
2015
Moulds responsible for black spot spoilage of dry-cured fermented sausages were characterised. For this purpose, samples were taken from those dry-cured fermented sausages which showed black spot alteration. Most of the mould strains were first tentatively identified as Penicillium spp. due to their morphological characteristics in different culture conditions, with one strain as Cladosporium sp. The Cladosporium strain was the only one which provoked blackening in culture media. This strain was further characterised by sequencing of ITS1-5.8S-ITS2 rRNA and β-tubulin genes. This mould strain was able to reproduce black spot formation in dry-cured fermented sausage 'salchichon' throughout th…
A temperature-type model for describing the relationship between fungal growth and water activity
2001
Growth of Penicillium chrysogenum, Aspergillus flavus, Cladosporium cladosporioides and Alternaria alternata at their respective optimum temperatures was studied in Potato Dextrose Agar (PDA) medium at different water activities (a(w)) adjusted with glycerol. The growth rate (mu) was expressed as the increase in colony radius per unit of time. This paper extends the model that showed the relationship between temperature and bacterial growth rate developed by Rosso et al. [J. Theor. Biol. 162 (1993) 447] to describe the influence of a(w) on fungal development. An excellent correlation between the experimental data and the model predictions was obtained, the regression coefficients (r2) were …