الفهرس 
AIM OF THE WORKOnly 14 pages are availabe for public view
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Abstract
Kariesh cheese is the most popular soft cheese consumed in Egypt especially in the countryside. Milk is used either in raw form or after pasterurization. Traditional Kariesh cheese is mainly produced from raw non-pasteurized milk.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. Microbial growth in cheese is enhanced by its high nutritive and low salt contents, which provide a favorable medium for the growth and multiplication of many microorganisms including bacteria and fungi.
Contamination with different microorganisms causes cheese spoilage and/or foodborne illnesses manifested as fever, nausea, vomiting, diarrhea, general malaise and weakness. Consumption of large amounts of contaminated cheese may result in outbreaks.
Our aim during this study was to assess some microbiological parameters of Kariesh cheese from some supermarkets and street vendors in Alexandria. The microbiological tests performed were: total plate count, estimation of total and fecal coliforms, detection of E. coli ,S. aureusas well as yeasts and moulds.
In the current study 270 samples were collected in the period between September 2015 and January 2016. Half of the samples (135) were collected from street vendors and the other half were collected from supermarkets. Samples were collected to cover 3 randomly selected districts in Alexandria, so that 90 samples were collected from each of West, Mid, and East districts of Alexandria.
The present study showed the following results:
1- Based on the district of collection of the present study, the East district had the highest mean of counts of the studied parameters which where as follows: total coliforms= 5.66 x102MPN/g, fecal coliforms= 3.43 x102 MPN/g and E.coli = 1.12 x102 MPN/g. On the other hand, the West district had the lowest mean of counts of the mentioned parameters and where as follows total coliforms= 1.15 x102MPN/g, fecal coliforms= 4.56 x10MPN/g and E.coli = 1.13x10 MPN/g.
2- The mean microbial counts in all tested parameters were higher in cheese sold by street vendors rather than supermarkets, and this was statistically significant. This reflects poor sanitary conditions performed by street vendors during production, transportation and storage of Kariesh cheese.
3- The 15 brands of Kariesh cheese sold at supermarkets were found to have different bacteriological parameters. Brand (B) was had the highest number ofthe total coliforms while brands (A),(E) and (J) were composed mainly of yeasts and molds showing the highest values.
4- In the present study, samples from 6 different farms were studied. Fecal coliforms, E.coliand yeasts and moulds were significantly different between various farms. This might be due to difference in production techniques as well aslack of governmental supervision on food hygiene. They probably do not follow the standard rules for proper manufacture, transportation and storage of Kariesh cheese.
5- It appears from the current data that most of the 135 Kariesh cheese samples purchased from street vendors were unsatisfactory according to the studied parameters, where 95.56% of those samples yielded > 400 CFU/g yeasts and moulds, 85.93% yielded ≥ 10 MPN/g total coliforms, 82.97% yielded fecal coliforms, 73.33% yielded E.coli and 12.59 % yielded S.aureus.
6- Most of the 135 Kariesh cheese samples purchased from supermarkets were satisfactory according to the aforementioned parameters except for the yeasts and molds, where only 6.7% were satisfactory. Samples purchased from supermarkets were significantly better than those from street vendors, (except for yeasts and moulds counts).
7- Current results revealed that the majority of samples (239 samples) were stored for only 1day. These samples included all samples (n= 135) sold by street vendors since they had no means of refrigerating their cheese. These samples had significantly high levels of total coliforms, fecal coliforms and E.coli.
8- The lowest storage temperature for Kariesh cheese was that of the refrigerator (4-5°C). Samples stored in that temperature had statistically significant lower numbers of total plate count, total coliforms, fecal coliforms and E.coli. Refrigeration lowers microbial multiplication but may also help the growth of psychrotolerant coliforms and some fungi.
In conclusion, the microbiological parameters of Kariesh cheese in this study showed unacceptable high levels, in both supermarkets as well as street vendors’ samples. This might be due to insufficient sanitation during manufacture, transportation and storage of this type of cheese. However, Kariesh cheese sold by supermarkets was less contaminated than those sold by street vendors. Brands sold at supermarkets had variable microbial composition, so did cheese coming from different farms. Kariesh cheese coming from nearer farms yielded lower microbial loads. Kariesh cheese stored at lower temperatures yielded lower microbial loads as well.