scholarly journals Determination of the survival kinetics of Salmonella spp. on the surface of ripened raw milk cheese during storage at different temperatures

2019 ◽  
Vol 55 (2) ◽  
pp. 610-618
Author(s):  
Adriana Lobacz ◽  
Jaroslaw Kowalik ◽  
Justyna Zulewska
Keyword(s):  
Raw Milk ◽  
Salmonella Spp ◽  
Different Temperatures ◽  
Raw Milk Cheese ◽  
Kinetics Of

scholarly journals Fate of Salmonella spp. in the Fresh Soft Raw Milk Cheese during Storage at Different Temperatures

2021 ◽  
Vol 9 (5) ◽  
pp. 938
Author(s):  
Adriana Lobacz ◽  
Justyna Zulewska
Keyword(s):  
Goodness Of Fit ◽  
Storage Temperature ◽  
Raw Milk ◽  
Microbial Count ◽  
Salmonella Spp ◽  
E Coli ◽  
Different Temperatures ◽  
Raw Milk Cheese ◽  
Kinetics Of ◽  
Storage Temperatures

The aim of this study was to determine the survival kinetics of Salmonella spp. in unripened, fresh raw milk cheese during storage at 5, 15 and 25 °C. Microbiological (coliforms and E. coli, S. thermophilus, Lactococcus sp., total microbial count and Enterobacteriaceae) and physicochemical (pH and aw) characteristics were also determined. Two primary models were used to estimate the kinetic parameters of Salmonella spp., namely Weibull and Baranyi and Roberts (no lag) models. Additionally, goodness-of-fit of the primary models was assessed by calculating the R-Square and mean square error. Salmonella spp. growth in the unripened raw milk cheese was inhibited during storage, but nevertheless bacteria survived at 5 °C for 33 days (2.5 log cfu/g) and 15 °C for 18 days (1.8 log cfu/g). A decrease in the number of Salmonella spp. populations from an initial concentration 6.6 log cfu/g to below a detection limit was observed at 25 °C after 7 days of storage of contaminated cheese samples. It was concluded that the storage temperature significantly influenced the inactivation rate of Salmonella spp. in fresh raw milk cheese and proceeded faster at 25 °C compared to remaining storage temperatures.

scholarly journals Simultaneous Determination of C18 Fatty Acids in Milk by GC-MS

Separations ◽  
2021 ◽  
Vol 8 (8) ◽  
pp. 118
Author(s):  
Meiqing Chen ◽  
Yangdong Zhang ◽  
Fengen Wang ◽  
Nan Zheng ◽  
Jiaqi Wang
Keyword(s):  
Fatty Acids ◽  
High Sensitivity ◽  
Raw Milk ◽  
Uht Milk ◽  
Milk Samples ◽  
Accuracy And Precision ◽  
Different Temperatures ◽  
Chromatographic Resolution ◽  
Commercial Milk

The determination of C18 fatty acids (FAs) is a key and difficult aspect in FA profiling, and a qualified method with good chromatographic separation and high sensitivity, as well as easy methylation, is required. A GC-MS method was established to simultaneously determine C18 FAs in milk. To simplify the methylation protocol for milk samples, besides a base-catalyzation methylation (50 °C for 20 min), the necessity of an additional acid-catalyzation was also studied using different temperatures (60 °C, 70 °C, 80 °C, and 90 °C) and durations (90 min and 150 min). The results showed that the chromatographic resolution was improved, although three co-eluted peaks existed. The base-catalyzation was sufficient, and an additional acid-catalyzation was not necessary. The proposed method was validated with good sensitivity, linearity, accuracy, and precision, and then applied in determining C18 FAs in 20 raw milk and 30 commercial milk samples. UHT milk presented a different profile of C18 FAs from raw milk and PAS milk samples, which indicated that excessive heating could change the profile. Overall, the proposed method is a high-throughput and competent approach for the determination of C18 FAs in milk, and which presents an improvement in chromatographic resolution and sensitivity, as well as a simplification of methylation.

Determination of Residual Stresses after Tensile Tests and Deep Drawing of Unstable Austenitic Steel

2005 ◽  
Vol 490-491 ◽  
pp. 690-695 ◽  
Author(s):  
M. Reda Berrahmoune ◽  
Sophie Berveiller ◽  
Karim Inal ◽  
Etienne Patoor ◽  
Christian R. Simon ◽  
...  
Keyword(s):  
Residual Stresses ◽  
Deep Drawing ◽  
Complex Loading ◽  
Tensile Tests ◽  
Loading Path ◽  
X Ray Diffraction ◽  
Martensite Content ◽  
Different Temperatures ◽  
Kinetics Of

The main objective of this work is to contribute to the study of the 301LN unstable austenitic stainless steel by determining the distribution of residual stresses after deep drawing, taking into account the phase transformation. In the first part, kinetics of martensitic transformation are determined for uniaxial loading. Tensile tests are performed at different pre-strains at room temperature for two different strain rates. The austenite/martensite content is measured by X-ray diffraction and is coupled with the determination of residual stresses distribution. In addition, to establish a relation between the complex loading path effect and the residual stresses state, deep drawing are done for different drawing ratios for two different temperatures. Macroscopic tangential residual stresses are determined by the separation technique. It appears that the residual stresses increase with increasing drawing ratios and the maximum value is located at middle height of the cup.

Influence of microorganisms on retinol isomerization in milk

2008 ◽  
Vol 75 (1) ◽  
pp. 37-43 ◽  
Author(s):  
Gianfranco Panfili ◽  
Alessandra Fratianni ◽  
Tiziana Di Criscio ◽  
Daniela Gammariello ◽  
Elena Sorrentino
Keyword(s):  
Microbiological Quality ◽  
Streptococcus Thermophilus ◽  
Raw Milk ◽  
Microbial Evolution ◽  
Different Temperatures ◽  
Quality Of Milk ◽  
Milk Storage ◽  
Insight Into

In order to have a deeper insight into the retinol isomerization phenomenon, in this work different milk samples have been analysed for their content of trans retinol and its cis-isomers, by means of reliable HPLC techniques. Levels of the different isomers and the degree of retinol isomerization (13-cis/all-trans ratio, %) have been monitored during milk storage at different temperatures and after addition of specific microorganisms. In raw milk stored at 4°C for 96 h the degree of retinol isomerization shifted from 1·1 to 2·3%, while in raw milk stored at 22°C for 24 h it increased from 1·1 to 12·7%. Among microorganisms tested in pasteurized milk, the most active in causing an increment in the 13-cis/all-trans ratio (%), from 3·4 to 33·4% in 8 h, was Streptococcus thermophilus. The results obtained demonstrated a relationship between microbial evolution and retinol isomerization. Therefore, the determination of retinol isomers is of importance not only for a more precise evaluation of vitamin A activity but also for the evaluation of the microbiological quality of milk.

scholarly journals Kinetic modeling of inactivation of foodborne bacterial pathogens in serrano artisanal cheese during ripening

2021 ◽  
Vol 24 ◽  
Author(s):  
Ângelo Nardi Pretto ◽  
Carolina Reck ◽  
Álvaro Menin ◽  
Voltaire Sant’Anna
Keyword(s):  
Experimental Data ◽  
Bacterial Pathogens ◽  
Raw Milk ◽  
Fecal Coliforms ◽  
Inactivation Kinetics ◽  
Salmonella Spp ◽  
First Order ◽  
Positive Strain ◽  
Log Linear ◽  
Kinetics Of

Abstract Serrano artisanal cheese is a traditional raw milk dairy product from southern Brazil. For safe consumption of raw milk products, ripening is a critical period for reducing populations of pathogenic and spoilage microorganism and, then, the knowledge on inactivation kinetics of microorganisms is necessary to guarantee food safety and quality. In the present work, inactivation kinetics of foodborne bacterial pathogens required by Brazilian regulations in serrano artisanal cheeses were statistically evaluated during ripening. The Salmonella spp., Listeria monocytogenes, coagulase-positive strain of Staphylococcus aureus and fecal coliforms were analyzed for up to 60 days. Experimental data were fitted using first-order model, Weibull and log-linear + shoulder models. Results showed no presence of Salmonella spp. and L. monogyatogenes in the cheeses through the studied period. The first-order and Weibull models presented good performance to represent coagulase-positive strain of S. aureus and fecal coliforms during ripening, although Weibull distribution showed better outcomes to experimental data. Log-linear+shoulder equation was discarded to describe the reduction of microorganism counts for physical criteria. Kinetics showed an initial resistance of fecal coliforms to be inactivated, unlike to coagulase-positive strain of S. aureus population. Modeling analysis allowed estimating serrano artisanal cheese ripening period to be longer than 33 days for achieving a safe product according to the Brazilian Regulatory Standards.

scholarly journals Determination of the occurrence of plasmid virulence genes (spv) and antibiotic resistance of Salmonella strains isolated from raw milk

2018 ◽  
Vol 74 (1) ◽  
pp. 59-64 ◽  
Author(s):  
AGNIESZKA WISZNIEWSKA-ŁASZCZYCH ◽  
BARBARA ZDRODOWSKA ◽  
BEATA WYSOK ◽  
JOANNA SZTEYN ◽  
KATARZYNA LIEDTKE ◽  
...  
Keyword(s):  
Antibiotic Resistance ◽  
Virulence Genes ◽  
Raw Milk ◽  
Molecular Methods ◽  
Frequency Of Occurrence ◽  
Salmonella Spp ◽  
Bulk Tank Milk ◽  
Milk Samples ◽  
Bulk Tank

The aim of the study was to measure the frequency of occurrence of Salmonella spp. in raw milk, to identify their serotype, as well as to determine their antibiotic resistance and the presence of Salmonella plasmid virulence (spv) genes. Out of 300 bulk tank milk samples, 5.3% were contaminated with Salmonella spp. All strains isolated belonged to the serovar S enteritidis, as confirmed by serotyping and molecular methods. The presence of spv genes was determined by PCR. Spv genes were present, in different patterns, in all strains tested. SpvA gene was present in all isolates (100%), spvB in 56.25%, spvC in 62.5%, spvD in 75%, and spvR in 56.25%. Antibiotic resistance was evaluated according to the NCCLS recommendations. All isolates were sensitive to ciprofloxacin (CIP), gentamicin (GE), and chloramphenicol (CH). Thirteen strains were resistant to ampicillin (AMP), 8 to erythromycin (E), 1 to doxycycline (DO), and 1 to tetracycline (TE). Different frequency of occurrence of the spv genes in Salmonella strains isolated from raw milk demonstrates their high adaptability. As many as 87.5% of isolates showed resistance to at least one of the antibiotics tested....

Bacteriological Survey of Freshly Formed Cheddar Cheese

1984 ◽  
Vol 47 (7) ◽  
pp. 546-548 ◽  
Author(s):  
MICHAEL H. BRODSKY
Keyword(s):  
Heat Treatment ◽  
Staphylococcus Aureus ◽  
Geometric Mean ◽  
Cheddar Cheese ◽  
Raw Milk ◽  
Fecal Coliforms ◽  
Salmonella Spp ◽  
Pasteurized Milk ◽  
Heat Treated ◽  
Raw Milk Cheese

Two hundred-fifty freshly formed cheese samples produced by 32 provincially inspected cheese plants were analyzed by 7 regional laboratories of the Ontario Ministry of Health. Coliforms were detected in 61 (25.8%) and fecal coliforms confirmed in 46 (19.5%) of the 236 samples tested, with geometric mean counts per g of 133 and 136, respectively. The incidence of coliforms was highest in Cheddar cheeses made from pasteurized milk (29.7%) compared with the incidence of raw milk cheese (22.0%) and cheese made from milk which had been subjected to sub-pasteurization heat treatment (28.2%). Conversely, the incidence of fecal coliforms was lowest in pasteurized milk cheese (17.8%), followed by raw milk cheese (22.0%) and highest in heat-treated milk cheeses (25.6%). Staphylococcus aureus above the screening level of 1000 per g was not found in any of the 237 samples analyzed. Salmonella spp. were not detected in any of the 250 samples. These results suggest that producers of Cheddar cheese should have no difficulty in meeting the microbiological standards adopted by the Health Protection Branch, Health and Welfare Canada.

scholarly journals Removal of Lead by Merlinoite Prepared from Sugarcane Bagasse Ash and Kaolin: Synthesis, Isotherm, Kinetic, and Thermodynamic Studies

Molecules ◽  
2021 ◽  
Vol 26 (24) ◽  
pp. 7550
Author(s):  
Tussaneetorn Chuenpratoom ◽  
Khuanjit Hemavibool ◽  
Kritsana Rermthong ◽  
Suwat Nanan
Keyword(s):  
Sugarcane Bagasse ◽  
High Performance ◽  
Maximum Adsorption Capacity ◽  
Lead Removal ◽  
Thermodynamic Studies ◽  
Different Temperatures ◽  
Pseudo Second Order ◽  
Sugarcane Bagasse Ash ◽  
Kinetics Of

This study introduces a merlinoite synthesized from sugarcane bagasse ash (SBA) and kaolin and evaluates its application as an adsorbent to remove lead from wastewater. The synthesis was performed via the hydrothermal method, and optimal conditions were determined. The adsorption of Pb by merlinoite was also optimized. Determination of the Pb2+ remaining in the aqueous solution was determined by atomic absorption spectroscopy (AAS). Adsorption isotherms were mainly studied using the Langmuir and Freundlich models. The Langmuir model showed the highest consistency for Pb adsorption on merlinoite, yielding a high correlation coefficient (R2) of 0.9997 and a maximum adsorption capacity (qmax) of 322.58 mg/g. The kinetics of the adsorption process were best described by a pseudo-second-order model. Thermodynamic studies carried out at different temperatures established that the adsorption reaction was spontaneous and endothermic. The results of this study show that merlinoite synthesized from kaolinite and SBA is an excellent candidate for utilization as a high-performance adsorbent for lead removal from wastewater.

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