scholarly journals Prevalence and behaviour of aeromonas hydrophila in raw milk and pefrigerated soft cheese

2001 ◽  
Vol 3 (1) ◽  
pp. 163-171
Author(s):  
Y El-Dweny
Keyword(s):  
Aeromonas Hydrophila ◽  
Raw Milk ◽  
Soft Cheese

Prevalence of Listeria species in raw milk, ice cream and yogurt and effect of selected natural herbal extract on its survival

2020 ◽  
Vol 21 (3) ◽  
pp. 99-106
Author(s):  
Mona Yousef ◽  
Hazem Ramadan ◽  
Maha Al-Ashmawy
Keyword(s):  
Plant Extract ◽  
Reduction Rate ◽  
Ice Cream ◽  
Raw Milk ◽  
Inhibitory Effect ◽  
Food Preservation ◽  
Herbal Extract ◽  
Listeria Species ◽  
Soft Cheese ◽  
High Reduction

Objective: This study aimed to detect the prevalence of Listeria species in raw milk, ice cream and yogurt, and to evaluate the effect of extract of clove, thyme and pomegranate peel on such organism. Design: Descriptive study. Procedures: One hundred and fifty samples of milk, ice cream and yogurt were examined for isolation, identification and molecular identification of Listeria spp. Extraction of natural plant extract as clove, thyme and pomegranate peels and detection of their inhibitory effect on Listeria spp. Results: The prevalence of Listeria spp. in milk was 36% where 14% as L. monocytogenes, 6% L. innocua and 16% and other Listeria spp. was 16%. In yogurt, Listeria spp. was 6% as L. innocua was 2% and other Listeria spp. was 4%, while no L. monocytogenes was detected. In ice cream, Listeria spp. was 8% where L. monocytogenes was 2% and other Listeria spp. was 6% while no L. innocua was detected. The concentration of plant extract was 2.5% which showed high reduction rate on L. innocua and L. monocytogenes during shelf life of soft cheese. Conclusion and clinical relevance: Listeria is widely isolated from milk than from ice cream and yogurt. Plant extracts play role in food preservation and consider as a natural antimicrobial agent where most effective one was clove extract.

scholarly journals Influence of soft cheese technology on the growth and enterotoxin production of Staphylococcus aureus

2009 ◽  
Vol 27 (No. 2) ◽  
pp. 127-133 ◽  
Author(s):  
L. Necidová ◽  
Z. Šťástková ◽  
M. Pospíšilová ◽  
B. Janštová ◽  
J. Strejček ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Technological Process ◽  
Raw Milk ◽  
Toxin Production ◽  
Milk Products ◽  
Model Experiments ◽  
Soft Cheese ◽  
Strict Compliance ◽  
Technological Processing ◽  
And Storage

The aim of this study was to monitor <I>S. aureus</I> growth and toxin production in soft cheese during the technological processing. In model experiments, raw milk was inoculated separately with five <I>S. aureus</I> strains isolated from milk and milk products. All the strains were producers of staphylococcal enterotoxins (SEs) of types A, B, or C. SEs were detected by the enzyme-linked fluorescence assay (ELFA) performed in the MiniVIDAS device. This study has shown that the amount of SEs varied with the tested strains and stages of the technological process. SEs were detected in soft cheese made from pasteurised milk inoculated with 2.9 × 10<sup>5</sup> CFU/g of <I>S. aureus</I>. The prevention of <I>S. aureus</I> contamination and multiplication during the cheese making process is a prerequisite for the production of safe soft cheese. The most important enterotoxin dose build-up factor can be overcome by strict compliance with the cooling requirements during the manufacture, distribution and storage of the product.

scholarly journals Antilisterial Activity of Bacteriocins Produced by Lactic Bacteria Isolated from Dairy Products

Foods ◽  
2020 ◽  
Vol 9 (12) ◽  
pp. 1757
Author(s):  
Simona de Niederhäusern ◽  
Stefania Camellini ◽  
Carla Sabia ◽  
Ramona Iseppi ◽  
Moreno Bondi ◽  
...  
Keyword(s):  
Dairy Products ◽  
Raw Milk ◽  
Lactobacillus Bulgaricus ◽  
Molecular Characteristics ◽  
Soft Cheese ◽  
Wide Range ◽  
Agar Well Diffusion Assay ◽  
Diffusion Assay ◽  
Lactic Bacteria ◽  
Selection Of

Sixty-nine Lactic Acid Bacteria (LAB) and bifidobacteria were isolated and identified from Italian dairy products (raw milk, cream, butter, soft cheese and yoghurt) to find new antimicrobial compounds to use as food bio-preservatives. All the isolates were preliminarily screened by the deferred antagonism method for bacteriocin production. Afterwards, to evaluate the release of bacteriocin in liquid medium, the Cell-Free Supernatant Fluid (CFSF) of the best producers was tested by agar well diffusion assay. The study allowed the selection of three bacteriocin producing strains (Enterococcus faecium E23, Bifidobacterium thermophilum B23 and Lactobacillus bulgaricus L21), endowed with the strongest and broadest inhibitory capability against the pathogen Listeria monocytogenes. The molecular characteristics and the chemical–physical properties of both producers and the respective bacteriocins were studied and compared. The results showed that E. faecium E23 was the best producer strain and its class IIa bacteriocins, called enterocin E23, exhibited a good spectrum of activity towards L. monocytogenes. Enterocin E23 was stable over a wide range of pH and at low temperatures for at least four months and, for this reason, it can be employed in refrigerated foods for the control of L. monocytogenes, the major concern in dairy products.

333. The coliform flora of milk and dairy products

1946 ◽  
Vol 14 (3) ◽  
pp. 233-282 ◽  
Author(s):  
E. L. Crossley
Keyword(s):  
Public Health ◽  
Dairy Products ◽  
Control Method ◽  
Milk Powder ◽  
Raw Milk ◽  
Great Utility ◽  
Soft Cheese ◽  
Confirmatory Tests ◽  
Dairy Plant ◽  
Plant Control

1. The sources of error and general significance of the presumptive coliform test have been studied, with special reference to manufactured dairy products.2. Eosine methylene blue agar has been found reasonably satisfactory for isolation of cultures but unsatisfactory as a direct plating medium.3. A wide survey of the coliform flora of raw milk and milk products has been made over a period of 11 years. The data were collected from 24,952 samples and include the incidence of presumptive positive tests at each stage of manufacturing processes, the occurrence of ‘false-positive’ tests, the detailed distribution of coliform types in individual dairy products, and some preliminary observations on ‘heat-resistant’ coliform strains.4. Material examined included raw milk, pasteurized milk, ice cream, milk powder, condensed milk, pasteurized cream, clotted cream, butter, soft cheese, Cheddar cheese, processed cheese, swabs of dairy plant, churn rinses, and the atmosphere of dairy factories.5. Detailed confirmatory tests were performed on 2490 presumptive positives, from which 2508 coliform cultures were isolated and classified.6. A general ecological survey of the frequency of individual coliform types in dairying operations as a whole has been attempted.7. Particular factors which may affect the distribution of coliform types in specific products or situations have been shown to include heat resistance, resistance to drying, chemical composition of the substrate, the effect of storage, and conditions prevailing on plant surfaces. It is suggested that the coliform flora may be partly the result of adaptation to conditions associated with each individual product.8. The value of the presumptive coliform test has been discussed in respect of public health requirements, as a plant-control method, and in relation to economic aspects. The test is believed to be of great utility in the plant-control laboratory but of little value for public health purposes.

scholarly journals Rapid detection of Listeria monocytogenes in raw milk and soft cheese by a redox potential measurement based method combined with real-time PCR

2014 ◽  
Vol 62 (3) ◽  
pp. 304-316 ◽  
Author(s):  
Orsolya Erdősi ◽  
Katalin Szakmár ◽  
Olivér Reichart ◽  
Zsuzsanna Szili ◽  
Noémi László ◽  
...  
Keyword(s):  
Listeria Monocytogenes ◽  
Redox Potential ◽  
Real Time ◽  
Real Time Pcr ◽  
Rapid Detection ◽  
Raw Milk ◽  
Food Samples ◽  
Potential Measurement ◽  
Effective Manner ◽  
Soft Cheese

The incidence of outbreaks of foodborne listeriosis has indicated the need for a reliable and rapid detection of the microbe in different foodstuffs. A method combining redox potential measurement and real-time polymerase chain reaction (PCR) was developed to detectListeria monocytogenesin artificially contaminated raw milk and soft cheese. Food samples of 25 g or 25 ml were homogenised in 225 ml of Listeria Enrichment Broth (LEB) with Oxford supplement, and the redox potential measurement technique was applied. ForListeriaspecies the measuring time was maximum 34 h. The absence ofL. monocytogenescould reliably be proven by the redox potential measurement method, butListeria innocuaandBacillus subtiliscould not be differentiated fromL. monocytogeneson the basis of the redox curves. The presence ofL. monocytogeneshad to be confirmed by real-time PCR. The combination of these two methods proved to detect < 10 cfu/g ofL. monocytogenesin a cost- and time-effective manner. This method can potentially be used as an alternative to the standard nutrient method for the rapid detection ofL. monocytogenesin food.

scholarly journals A community-wide outbreak of Salmonella enterica serotype Typhimurium infection associated with eating a raw milk soft cheese in France

2000 ◽  
Vol 124 (1) ◽  
pp. 1-7 ◽  
Author(s):  
H. DE VALK ◽  
E. DELAROCQUE-ASTAGNEAU ◽  
G. COLOMB ◽  
S. PLE ◽  
E. GODARD ◽  
...  
Keyword(s):  
Salmonella Enterica ◽  
Case Control Study ◽  
Phage Type ◽  
Raw Milk ◽  
Distribution Channels ◽  
Case Control ◽  
Processing Plant ◽  
Soft Cheese ◽  
Community Controls ◽  
Control Study

In 1997, a community-wide outbreak of Salmonella enterica serotype Typhimurium (S. typhimurium) infection occurred in France. The investigation included case searching and a case-control study. A case was defined as a resident of the Jura district with fever or diarrhoea between 12 May and 8 July 1997, from whom S. typhimurium was isolated in stool or blood. One hundred and thirteen cases were identified. Thirty-three (83%) of 40 cases but only 23 (55%) of 42 community controls, matched for age and area of residence, reported eating Morbier cheese (Odds ratio: 6·5; 95% Confidence Interval: 1·4–28·8). Morbier cheese samples taken from the refrigerators of two case-patients and one symptom-free neighbour cultured positive for S. typhimurium of the same phage type as the human isolates. The analysis of distribution channels incriminated one batch from a single processing plant. These findings show that an unpasteurized soft cheese is an effective vehicle of S. typhimurium transmission.

scholarly journals The combined effect of bacteriocin-producing Lactobacillus rhamnosus GG-ATCC and Lactoperoxidase system activation on microbiological quality of raw milk with special emphasis against E.coli O157:H7 in milk

2017 ◽  
Vol 40 (2) ◽  
pp. 66-72
Author(s):  
Najim Hadi Najim
Keyword(s):  
Storage Temperature ◽  
Lactobacillus Rhamnosus ◽  
Microbiological Quality ◽  
Raw Milk ◽  
Latex Agglutination ◽  
Bacterial Cells ◽  
Lactobacillus Rhamnosus Gg ◽  
Time Period ◽  
Soft Cheese ◽  
Chromogenic Agar

     Isolates of Enterohaemorrhagic E.coli O157:H7 were isolated from 51 and 41 of locally produced bovine and ovine soft cheese samples. Their identification were confirmed based on the biochemical reactions and both the morphological cultural and serological properties. Presumptive E.coli O157:H7 isolates obtained by using the conventional selective plating on the chromogenic agar were tested further for the presence of both O157 and H7 antigenes using the latex agglutination test antisera. The current microbiological studies revealed that 31 (33.70 %) out of 92 bovine and ovine soft cheese samples were positive for E.coli O157:H7. The highest non significant (P>0.05) prevalence level of E.coli O157:H7 was found in the ewe᾿s soft cheese samples (36.59 %) followed by cow᾿s soft cheese samples (31.37 %). Agar well diffusion bioassay method was used for measuring the antibacterial activity of the crude bacteriocin that was produced by Lactobacillus rhamnosus GG-ATCC against Escherichia coli and the closely related sensitive strains such as L.acidophilus LA-K and L.acidophilus ROO52. The crude bacteriocin that was produced by the L.rhamnosus GG-TACC exhibited significantly (P<0.05) the highest antibacterial potency (100 %) against both the closely related strains of lactobacilli and the stressed E.coli O157:H7 by the activation of the LPS. The activation of the natural LPS of inoculated pasteurized milk had significantly (P<0.05) influenced the inactivation degree of the crude bacteriocin against E.coli O157:H7. There was a significant (P<0.05) reduction in the viable counts of stressed E.coli O157:H7 after each exposure time period (6, 24 and 48 hrs.) to the crude bacteriocin at room storage temperature. An overall conclusion on the basis of the current results pointed  out  that complete  elimination of viable bacterial cells was not achieved  neither  in  the stabilized milk (Activation of LPS) nor after  subjecting  the stabilized  milk to the action of the crude bacteriocin produced by L.rhamnosus GG-ATCC at room storage temperature.

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