10. Microbiological characterization of the Egyptian soft white cheese and identification of its dominant yeasts (original) (raw)
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We conducted this study to evaluate the differences in microflora and physicochemical properties of some traditionally manufactured soft white cheeses upon purchase from Zagazig city, Egypt, in 2010 and 2011. A total of 168 samples were analyzed for both spoilage (total viable count, lactic acid bacteria, yeasts and moulds, staphylococci, Enterobacteriaceae, and coliform group) and pathogenic (Salmonella spp., Escherichia coli, Staphylococcus aureus, and fecal Streptococci) microorganisms. Physicochemical analyses showed low levels of pH and high levels of salt. Two cheese samples were unsatisfactory due to levels of Staphylococcus aureus at 4.00 log cfu/g, and fecal streptococci at 4.3 log cfu/g. Despite the much lower spoilage microorganisms counts in the pasteurized cheeses, soft Feta of dairy M showed the highest contamination level of 4.11 and 3.72 log cfu/g of total viable count and staphylococci, respectively. Fifty-two isolates of the yeasts were identified using the physiological and biochemical tests, and were classified into seven species. Ten of the species were selected for identification by sequencing the 26S rRNA, where nine of them were identical to the phenotypic identification. These results emphasize the need for applying more strict hygienic practices especially in thermized cheese processing to minimize microbial contamination.
2013
We conducted this study to evaluate the differences in microflora and physicochemical properties of some traditionally manufactured soft white cheeses upon purchase from Zagazig city, Egypt, in 2010 and 2011. A total of 168 samples were analyzed for both spoilage (total viable count, lactic acid bacteria, yeasts and moulds, staphylococci, Enterobacteriaceae, and coliform group) and pathogenic (Salmonella spp., Escherichia coli, Staphylococcus aureus, and fecal Streptococci) microorganisms. Physicochemical analyses showed low levels of pH and high levels of salt. Two cheese samples were unsatisfactory due to levels of Staphylococcus aureus at 4.00 log cfu/g, and fecal streptococci at 4.3 log cfu/g. Despite the much lower spoilage microorganisms counts in the pasteurized cheeses, soft Feta of dairy M showed the highest contamination level of 4.11 and 3.72 log cfu/g of total viable count and staphylococci, respectively. Fifty-two isolates of the yeasts were identified using the physiol...
Seventy five random samples (50 of small scale and 25 large scale produced soft cheese) were collected from different localities in Zagazig city, Sharkia Governorate, Egypt to be examined microbiologically. The mean total colonies of, Staphylococci, Coliforms, Enterococcus faecalis, Ent. faecium, Ent. intermediate and yeast and mould count/g. in examined small scale and large scale produced soft cheese samples were 3.9X10 8 & 2.6X10 4 , 7X10 4 & 0 , 6.0X10 4 & 0 , 2.2X10 5 & 0 , 1.9X10 5 & 0 , 3.0X10 4 & 0 , 5.8X10 4 and 7.9X10 3 , respectively. Staphylococcus aureus and Staphylococcus epidermidis were the predominated Staphylococci isolated from the examined small scale produced soft cheese samples and the most prevalent Coliform species were Klebsiella terrigena, Kleb. Planticola, Citrobacter diversus, Enterobacter agglomerans, Ent. amnigenus biogroup 1 and Ent. amnigenus biogroup 2. Salmonellae could not be detected in all examined samples. The sanitary and public health importance of isolated microorganisms as well as their control measures were discussed to improve the quality of soft cheese and safeguard the consumers from infection.
Microbiological Quality in Egyptian White Soft Cheese
2013
The quality evaluation of white soft cheese in the Egyptian markets is an urgent need to create awareness among population about the existing situation and to protect the consumer's health and rights. Thus, the aim of this work was to determine AFM levels and evaluate microbiological properties in 1 commercially available white soft cheese collected from local markets as well as to evaluate the manufactured control samples using the Hazard Analysis Critical Control Points (HACCP) system. Results revealed that AFM1 concentration was detected in almost half of the samples (46.66%) with an overall mean of 14.39 ng/kg and was detected in 24 samples at levels below 1.0 ng/kg and in 15 samples at levels ranging from 10 to 50 ng/kg, whereas about 3 samples were higher than 50 ng/kg. All positive samples of white cheeses exceeded the Egyptian regulations (free from AFM ). The microbiological analysis revealed that all samples contained high 1
Journal of Microbial & Biochemical Technology, 2016
The aim of this study was to evaluate the bacteriological quality and safety of fresh white cheese sold in Tripoli, Libya. The study lasted for approximately 7 months (November 2011-May 2012), during this period 87 fresh white cheese samples were collected from seven different areas (4 to 5 factories from each area with the rate of 3 duplicates). The samples were tested for temperature at receiving, pH and acidity, total aerobic counts, total coliform counts and the detection of incidence of some pathogenic bacteria including: Escherichia coli, Escherichia coli O157:H7, Staphylococous aureus, Salmonella spp., Aeromonas hydrophila and Listeria monocytogenes. Results indicated that the average temperature, % acidity, and pH of the tested samples were (15.80°C ± 5.8, 0.21 ± 0.02% and 5.81 ± 0.06) respectively. Data indicated that 70.1% of the samples exceeded the Libyan standard for white cheese No. 366 in respect to temperature, while pH of all samples was within the limits of such standard. On the other hand, means of total aerobic counts, total coliform counts, and the numbers of Staphyloccoccus aureus were (38 × 10 7 , 74 × 10 5 , 35 × 10 4 and 53 × 10 3 cfu/g) respectively of the study. b ia l & Bioc h e m ic a l Te chno lo g y
Acta agriculturae slovenica, 2004
The microbiological quality of 98 samples taken at some critical control points during the milking and processing of 14 semi-hard cheese made from raw cow milk by individual Slovenian producers was studied. The sampling points were: swabs from cows' udders, milking machines inner surfaces before and after milking, fresh raw and mixed milk from vats, whey immediately after curdling, brine, cheese after one month of ripening and after the following month of being kept vacuum packed at 6 °C. The high number of microorganisms on the inner surfaces of washed milking machines before milking revealed ineffective cleaning (washing) by about 60% of cheese producers. There were no seasonal differences in the number of microorganisms, except that the number of coliforms was higher in spring. The average of total number of microorganisms was 4.9•10 5 cfu/ml in raw milk and 5.5•10 6 cfu/ml in mixed milk from a vat (raw fresh milk mixed with milk kept for about 18-24 hours at room temperature), which did not grow significantly during cheese-processing. The number of coliforms in raw and mixed milk was in the range of 3.4•10 5 cfu/ml and fell to 5.4•10 4 cfu/ml in whey. The average number of enterococci, aerobic spore-forming microorganisms , yeasts and moulds, lactobacilli, lactococci, proteolytic and lipolytic microorganisms in milk and in whey were in the same logarithmic range of about 2.2•10 4 , 310, 3.5, 31.2•10 4 , 2.1•10 6 , 6.2•10 3 and 1.7•10 4 cfu/ml of the sample, respectively. Listeria spp. was isolated from 5.3% (cows' udders, milking machine, milk and whey), while none of the examined samples were positive to the presence of Salmonella spp. and Campylobacter spp. Proteus was present in 7 (7%) cases of milk and whey. Clostridia were detected in 10 (10%) samples (swabs, raw milk, whey). E. coli was isolated from 12 (12%) samples of swabs, raw and mixed milk, whey and brine. After one month of ripening the average total bacterial count was 9.2•10 7 cfu g-1 of cheese, of these 6.8•10 7 represented lactic-acid producers and 2.2•10 7 represented non-lactic acid producers. The average number of coliforms, enterococci, aerobic spore-forming microorganisms , yeasts and moulds, lactococci, lactobacilli, proteolytic and lipolytic microorganisms were 2.0•10 5 , 6.3•10 6 , 280, 960, 2.5•10 7 , 9.8•10 7 , 450 and 9.8•10 4 cfu g-1 of cheese, respectively. Salmonella spp., Listeria spp., Proteus, sulphitereducing clostridia and Campylobacter spp. were not detected in cheese samples. E. coli was found in 4 (30%) of samples while coagulase positive staphylococci were present in 9 (64%) of cheese samples. A high number of enterococci (from a min. 3.10 3 to a max. 15.10 7 cfu g-1) and coliforms (from a min. 10 to a max. 19.10 5 cfu g-1) were detected as well. After one month of keeping vacuum-packed ripened cheeses at 6 °C, the number of microorganisms did not rise significantly, except for the number of yeasts and moulds which grew to 3.6•10 4 cfu g-1 of cheese. Because of improper milking and processing hygiene conditions, three (21%) of the tested cheese samples did not correspond to the microbiological criteria according to the applicable regulations.
Determination of microbiological contamination sources during Turkish white cheese production
Food Control, 2006
This study has been conducted to determine the microbiological contamination sources during production of white cheese in a local dairy plant, Bursa, Turkey. Twenty nine different control points or sample types (raw milk, pasteurized milk, milk in cheese vat, curd, moulded cheese before salting, moulded cheese after salting, cheese at cold holding and vacuum packaged cheese; samples from starter culture, rennet, calcium chloride solution, brine, cheese vat, cheese cloth, polyethylene separator sheet, milk stirrer, curd cutting knife, side pressure plate, upper pressure plate, moulded cheese cutting knife, cheese tray, packaging material used during production; workersÕ hands, cold room and production room air, floor, wall, and potable water) have been examined for the enumeration of total aerobic mesophilic bacteria, staphylococci, coagulase positive staphylococci, Enterobacteriaceae, enterococci, coliforms, Escherichia coli, psychrophilic bacteria, and yeast and molds. We determined: starter culture as the possible contamination source of coagulase positive staphylococci, enterococci and psychrophilic bacteria; brine and upper pressure plate as the contamination source for staphylococci; floor and packaging material as the contamination source of psychrophilic bacteria; cheese vat, cheese cloth and curd cutting knife as the contamination source of total aerobic mesophilic bacteria; cold room and production room air as the contamination sources for yeast and molds.
Journal of High Institute of Public Health
Background: Kariesh cheese is the most popular soft cheese consumed in Egypt especially in the countryside. Some of Kariesh cheese is produced in equipped factories, but most in farmers' homes and unlicensed places not under standard requirements for hygienic food production. Cheese could be contaminated by different types of microorganisms during its production, handling, distribution and storage under unhygienic conditions. Contamination with different microorganisms causes cheese spoilage and/or foodborne illnesses. Objective(s): To assess some microbiological parameters of Kariesh cheese, as recommended by the Egyptian standards for Kariesh cheese No.1008/2000. A comparison of Kariesh cheese samples collected from supermarkets and street vendors was carried out. Methods: A total of 270 Kariesh cheese samples were collected in the period between September 2015 and January 2016 from 3 randomly selected Alexandrian districts. Half of the samples (135) were collected from street vendors and the other half was collected from supermarkets. The microbiological tests performed were: total plate count, estimation of total and fecal coliforms, and detection of E. coli, S. aureus as well as yeasts and moulds. Results: According to the Egyptian standard No.1008/2000 for Kariesh cheese parameters, only 6% and 7% of the examined Kariesh samples were satisfactory for yeasts and moulds and total plate count respectively. As regards total coliforms and E.coli, 44% and 48% respectively of the samples were satisfactory, while 39% of the samples were satisfactory for fecal coliforms, and around 90% were for S. aureus. The mean microbial counts in all tested parameters were higher in Kariesh cheese samples sold by street vendors rather than supermarkets, and this was statistically significant. Conclusions: The microbiological parameters of Kariesh cheese in this study showed unacceptable high levels especially among street vendors' samples.
Acta agriculturae Slovenica, 2006
The presence of pathogenic and some indicator micro organisms was studied in 40 samples of cheese comprising 14 curd samples, 13 samples of soft ripened salted or non-salted cheese and 13 samples of semi-hard cheese manufactured at five small dairy-processing plants. The mean number of coagulase-positive staphylococci in all tested samples was 2.5 × 10 4 cfu * g-1 , while the number of E. coli bacteria was 1.4 × 10 6 cfu g-1. In 20.0% out of 40 samples tested, the number of coagulase-positive staphylococci exceeded the prescribed regulations, particularly in soft cheese (12.5%) and curd (7.5%). About 17.5% of samples were contaminated with E. coli in higher concentrations than national valid regulations allowed. The number of E. coli was mostly exceeded in soft cheese and curd in 12.5% and 5.0% of all examined samples, respectively. One sample of semi hard cheese was contaminated with sulphite-reducing clostridia. Proteus was detected in 3 samples (7.5%) and L. grayi in 1 (2.5%) sample. Salmonela and L. monocytogenes were not detected. According to the valid regulations 9 (22.5%) samples in our investigation did not reach the adequate microbiological quality. Both, yeasts and moulds were isolated from 60% of tested cheese samples with average concentrations of 5.8 × 10 4 cfu g-1 and 2.0 × 10 4 cfu g-1 , respectively. The genera Geotrichum (91.9%), Moniliella (5.4%) and Aspergillus (2.7%) were the most frequently isolated strains from examined cheese samples. The Aspergillus strains did not belong to the species A. flavus or A. parasiticus and did not produce aflatoxins.