scholarly journals Microbiological Characteristics and Behavior of Staphylococcus aureus, Salmonella spp., Listeria monocytogenes and Staphylococcal Toxin during Making and Maturing Cotija Cheese

2021 ◽  
Vol 11 (17) ◽  
pp. 8154
Author(s):  
María de los Ángeles Olea-Rodríguez ◽  
Patricia Chombo-Morales ◽  
Karla Nuño ◽  
Olga Vázquez-Paulino ◽  
Zuamí Villagrán-de la Mora ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Listeria Monocytogenes ◽  
Health Risks ◽  
Salmonella Spp ◽  
Ripening Process ◽  
Initial Inoculum ◽  
Staphylococcal Toxin ◽  
Unpasteurized Milk ◽  
Microbiological Characteristics ◽  
And Behavior

Cotija cheese is an artisanal matured Mexican cheese from unpasteurized milk. This work determined the microbiological characteristics and behavior of Staphylococcus aureus, Salmonella spp., Listeria monocytogenes and staphylococcal toxin during cheese elaboration and ripening. Sixteen 20-kg cheeses were used, eight inoculated with 6 log CFU/mL of each pathogen, and eight uninoculated, and samples were taken at each stage of the process. In the uninoculated samples, the survival of S. aureus and L. monocytogenes decreased after 30 days of ripening. The average counts of S. aureus in milk, curd, and serum were 7 log MPN /mL, and 8.7 log MPN /g in cheese, decreasing from day 15. Salmonella spp. counts (initial inoculum: 7.2 log MPN /mL) decreased after 24 h, and L. monocytogenes counts (8.7 log MPN/g at 24 h) decreased from day 15 in the cheese. Salmonella spp. and L. monocytogenes were not detected in any sample after 60 days of ripening, unlike S. aureus, which was detected at the end of the study. Lactic acid bacteria counts were 9 log CFU/mL in milk and whey and 7.2 log CFU/g in cheese. Pathogens behavior during the ripening process reduces the health risks by consuming products made with unpasteurized milk when subjected to ripening.

Viability Loss of Salmonella Species, Staphylococcus aureus, and Listeria monocytogenes in Complex Foods Heated by Microwave Energy

1996 ◽  
Vol 59 (8) ◽  
pp. 813-818 ◽  
Author(s):  
RONALD A. HEDDLESON ◽  
STEPHANIE DOORES ◽  
RAMASWAMY C. ANANTHESWARAN ◽  
GERALD D. KUHN
Keyword(s):  
Staphylococcus Aureus ◽  
Listeria Monocytogenes ◽  
Chemical Composition ◽  
Food Systems ◽  
Sodium Content ◽  
Salmonella Spp ◽  
Uht Milk ◽  
Mixed Mean ◽  
Liquid Whole Egg ◽  
And Staphylococcus Aureus

The chemical composition of five foods (UHT milk, beef broth, pudding, cream sauce, and liquid whole egg) was examined to determine factors important in achieving uniform temperatures within foods heated in a 700 W microwave oven. Proximate analyses were performed on all food systems to relate their chemical composition to temperatures and to destruction of microwave-heated Salmonella species, Listeria monocytogenes Scott A and V7 and Staphylococcus aureus ATCC 25923. Microwave heating times were chosen such that the final mixed mean temperature achieved by systems was 60°C for Salmonella spp. and L. monocytogenes, and 65°C for S. aureus. The amount of destruction of Salmonella spp. varied from 3.17 log CFU/ml in UHT milk to 0.44 log CFU/ml in beef broth. L. monocytogenes strains incurred the greatest amount of destruction in pudding (2.39 log CFU/g), while the least amount of destruction was observed in cream sauce (1.63 log CFU/ml). There were no significant differences in the amount of destruction of S. aureus heated in the five foods. The pH and aw of these foods did not affect survival of thermally stressed Salmonella, L. monocytogenes, or S. aureus cells. Of the food components examined, sodium content was the primary influence on the uniformity of temperatures achieved within foods, and, in turn, on the survival of bacteria.

scholarly journals Growth inhibition of foodborne pathogens in camel milk: Staphylococcus aureus, Listeria monocytogenes, Salmonella spp. and E. coli O157:H7

2017 ◽  
Vol 35 (No. 4) ◽  
pp. 311-320 ◽  
Author(s):  
Abusheliabi Aisha ◽  
Al-Holy Murad A ◽  
Al-Rumaithi Hind ◽  
Al-Khaldi Sufian ◽  
Al-Nabulsi Anas A ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Listeria Monocytogenes ◽  
Growth Inhibition ◽  
Foodborne Pathogens ◽  
Bovine Milk ◽  
Growth Patterns ◽  
Camel Milk ◽  
Salmonella Spp ◽  
E Coli ◽  
Milk Samples

The growth behaviour of foodborne pathogens (Staphylococcus aureus, Listeria monocytogenes, E. coli O157:H7 and Salmonella spp.) was investigated in pasteurised camel milk and compared with pasteurised bovine milk at different incubation temperatures. This study also aimed to compare the growth patterns of these four foodborne pathogens in pasteurised and raw camel milk. Pasteurised or raw camel milk and pasteurised bovine milk were separately inoculated with a cocktail of three strains of each foodborne pathogen. The inoculated milk samples were incubated at 10, 25, and 37°C. The total bacterial count (TBC) in raw milk and the total thermoduric bacteria count (TDB) in pasteurised milk samples were monitored. Greater growth inhibition rates of four pathogens were obtained for the pasteurised camel milk compared to the pasteurised bovine milk. Raw and pasteurised camel milk exerted bacteriostatic effect against all tested pathogens, particularly for the first 8 h of incubation in milk at the different temperatures. Pasteurised camel milk exerted an inhibitory activity that was equivalent to that of raw camel milk.

Survival of Escherichia coli O157:H7, Salmonella Enteritidis, Staphylococcus aureus, and Listeria monocytogenes in Kimchi

2004 ◽  
Vol 67 (7) ◽  
pp. 1497-1500 ◽  
Author(s):  
Y. INATSU ◽  
M. L. BARI ◽  
S. KAWASAKI ◽  
K. ISSHIKI
Keyword(s):  
Escherichia Coli ◽  
Staphylococcus Aureus ◽  
Listeria Monocytogenes ◽  
Incubation Period ◽  
Salmonella Enteritidis ◽  
Detectable Level ◽  
Escherichia Coli O157 ◽  
Inoculum Level ◽  
Initial Inoculum ◽  
E Coli

The survival of gram-positive and gram-negative foodborne pathogens in both commercial and laboratory-prepared kimchi (a traditional fermented food widely consumed in Japan) was investigated. It was found that Escherichia coli O157:H7, Salmonella Enteritidis, Staphylococcus aureus, and Listeria monocytogenes could survive in both commercial and laboratory-prepared kimchi inoculated with these pathogens and incubated at 10°C for 7 days. However, when incubation was prolonged, the S. aureus level decreased rapidly from the initial inoculum level to the minimum detectable level within 12 days, whereas Salmonella Enteritidis and L. monocytogenes took 16 days to reach similar levels in commercial kimchi. On the other hand, E. coli O157:H7 remained at high levels throughout the incubation period. For laboratory-prepared kimchi, the S. aureus level decreased rapidly from the initial inoculum level to the minimum detectable level within 12 days, and L. monocytogenes took 20 days to reach a similar level. E. coli O157:H7 and Salmonella Enteritidis remained at high levels throughout the incubation period. The results of this study suggest that the contamination of kimchi with E. coli O157:H7, Salmonella Enteritidis, S. aureus, or L. monocytogenes at any stage of production or marketing could pose a potential risk.

Growth of Listeria monocytogenes, Salmonella spp., Escherichia coli O157:H7, and Staphylococcus aureus on Cheese during Extended Storage at 25°C

2014 ◽  
Vol 77 (8) ◽  
pp. 1275-1288 ◽  
Author(s):  
WAN MEI LEONG ◽  
RENAE GEIER ◽  
SARAH ENGSTROM ◽  
STEVE INGHAM ◽  
BARBARA INGHAM ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Staphylococcus Aureus ◽  
Listeria Monocytogenes ◽  
Water Activity ◽  
Titratable Acidity ◽  
Study Data ◽  
Escherichia Coli O157 ◽  
Salmonella Spp ◽  
Require Time ◽  
And Staphylococcus Aureus

Potentially hazardous foods require time/temperature control for safety. According to the U.S. Food and Drug Administration Food Code, most cheeses are potentially hazardous foods based on pH and water activity, and a product assessment is required to evaluate safety of storage >6 h at 21°C. We tested the ability of 67 market cheeses to support growth of Listeria monocytogenes (LM), Salmonella spp. (SALM), Escherichia coli O157:H7 (EC), and Staphylococcus aureus (SA) over 15 days at 25°C. Hard (Asiago and Cheddar), semi-hard (Colby and Havarti), and soft cheeses (mozzarella and Mexican-style), and reduced-sodium or reduced-fat types were tested. Single-pathogen cocktails were prepared and individually inoculated onto cheese slices (~105 CFU/g). Cocktails were 10 strains of L. monocytogenes, 6 of Salmonella spp., or 5 of E. coli O157:H7 or S. aureus. Inoculated slices were vacuum packaged and stored at 25°C for ≤15 days, with surviving inocula enumerated every 3 days. Percent salt-in-the-moisture phase, percent titratable acidity, pH, water activity, and levels of indigenous/starter bacteria were measured. Pathogens did not grow on 53 cheeses, while 14 cheeses supported growth of SA, 6 of SALM, 4 of LM, and 3 of EC. Of the cheeses supporting pathogen growth, all supported growth of SA, ranging from 0.57 to 3.08 log CFU/g (average 1.70 log CFU/g). Growth of SALM, LM, and EC ranged from 1.01 to 3.02 log CFU/g (average 2.05 log CFU/g), 0.60 to 2.68 log CFU/g (average 1.60 log CFU/g), and 0.41 to 2.90 log CFU/g (average 1.69 log CFU/g), respectively. Pathogen growth varied within cheese types or lots. Pathogen growth was influenced by pH and percent salt-in-the-moisture phase, and these two factors were used to establish growth/no-growth boundary conditions for safe, extended storage (≤25°C) of pasteurized milk cheeses. Pathogen growth/no-growth could not be predicted for Swiss-style cheeses, mold-ripened or bacterial surface–ripened cheeses, and cheeses made with nonbovine milk, as insufficient data were gathered. This challenge study data can support science-based decision making in a regulatory framework.

scholarly journals Standardization of a rapid quadruplex PCR method for the simultaneous detection of bovine, buffalo, Salmonella spp., and Listeria monocytogenes DNA in milk

2021 ◽  
Vol 73 (4) ◽  
pp. 781-790
Author(s):  
J.S. Lima ◽  
A.P.P.O. Sampaio ◽  
M.C.S. Dufossé ◽  
A.M.B.P. Rosa ◽  
P.F.M. Sousa ◽  
...  
Keyword(s):  
Listeria Monocytogenes ◽  
Dna Sequences ◽  
Performance Optimization ◽  
Genetic Material ◽  
Simultaneous Detection ◽  
Buffalo Milk ◽  
Salmonella Spp ◽  
Initial Inoculum ◽  
Target Dna ◽  
Pcr Method

ABSTRACT The objective of the present study was to Standardize a Polymerase Chain Reaction (PCR) protocol for the authentication of bovine and buffalo milk, and to detect the presence of Salmonella spp. and Listeria monocytogenes. For this, the target DNA was extracted, mixed, and subjected to a PCR assay. Milk samples were defrauded and experimentally contaminated with microorganisms to assess the detection of target DNA at different times of cultivation, bacterial titers, and concentration of genetic material. In addition, the protocol was tested with DNA extracted directly from food, without a pre-enrichment step. The proposed quadruplex PCR showed good accuracy in identifying target DNA sequences. It was possible to simultaneously identify all DNA sequences at the time of inoculation (0h), when the samples were contaminated with 2 CFU/250mL and with 6h of culture when the initial inoculum was 1 CFU/250mL. It was also possible to directly detect DNA sequences from the food when it was inoculated with 3 CFU/mL bacteria. Thus, the proposed methodology showed satisfactory performance, optimization of the analysis time, and a potential for the detection of microorganisms at low titers, which can be used for the detection of fraud and contamination.

scholarly journals Qualidade microbiológica do leite refrigerado nas fazendas

2006 ◽  
Vol 58 (3) ◽  
pp. 440-446 ◽  
Author(s):  
E.F. Arcuri ◽  
M.A.V.P. Brito ◽  
J.R.F. Brito ◽  
S.M. Pinto ◽  
F.F. Ângelo ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Listeria Monocytogenes ◽  
Streptococcus Agalactiae ◽  
Salmonella Spp

Avaliaram-se a qualidade microbiológica do leite obtido mecanicamente e refrigerado durante 48 horas, em 24 rebanhos, e a associação entre a contaminação microbiana e os procedimentos de higienização dos equipamentos de ordenha e armazenamento do leite. Os procedimentos de higiene foram avaliados in loco com auxilio de questionários. Foram realizadas a contagem padrão em placas, a contagem de coliformes totais e a pesquisa de Staphylococcus aureus e Streptococcus agalactiae. No leite de 14 rebanhos, foram pesquisadas Salmonella spp. e Listeria monocytogenes. As médias geométricas da contagem padrão foram <1,0×10(6) UFC/ml em 20 rebanhos, e <7,5×10(5) UFC/ml em 19. Onze rebanhos apresentaram contagem média de <1,0×10(5) UFC/ml. Contagens médias de coliformes >10³ UFC/ml foram verificadas em sete rebanhos. S. aureus e S. agalactiae foram isolados em 22 e 12 dos 24 rebanhos, respectivamente, e não foram encontradas Salmonella spp. e L. monocytogenes. O uso de detergentes alcalino e ácido, mais o de sanitizante foi associado (P<0,05) à contagem padrão <1,0×10(5), e o emprego de apenas um ou de nenhum produto foi associado a contagens >5×10(5) UFC/ml.

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