الفهرس 
Cover Page Title in EnglishOnly 14 pages are availabe for public view
 |  | from | 110 |  |  |
| | | from | 110 | | |
Abstract
One –hundred and twenty samples of Kareish cheese, processed cheese and Ice cream (40 of each) were collected from street-vendors at El-Behera province. The samples were obtained as sold to the public and transferred as soon as possible to the laboratory to be examined. All samples were examined organolepticaly before being subjected to some chemical and microbiological examinations to ensure that the samples were apparently fit for consumption.
The result can be summarized as follows:
1. Compositional quality tests:
1.1. Kareish cheese and processed cheese:
Acidity percent: the mean values of acidity percent in Kareish cheese and processed cheese samples were 1.17 ± 0.662 and 1.94 ± 0.06, respectively.
Sodium chloride content: the mean values were 4.02 ± 0.220 and 5.12 ± 0.01, respectively.
Moisture content: the mean values were 65.31 ± 0.73 and 51.23 ± 0.59, respectively.2 (4%) of examined Kareish cheese samples were proved to be above Egyptian standards.
1.2. Ice cream:
Methylene blue reduction test: there were 20%of samples of grade I, 17.5%of grade II, 50% of grade III, and 15% of grade IV.
2. Bacterial examination:
2.1. The incidence of E.coli of the examined Kareish cheese, Processed cheese and Ice cream samples were 40%, 5% and 30% respectively.
2.2. The incidence of Staphylococcus aureus count of the examined Kareish cheese, Processed cheese and Ice cream samples were 45%, 5% and 27.5% respectively.
2.3. The incidence of Aeromonas hyDROPhila of the examined Kareish cheese, Processed cheese and Ice cream samples were 32.5%, 7.5% and 40% respectively.
2.4. The incidence of Pseudomonas aeruginosa of the examined Kareish cheese, Processed cheese and Ice cream samples were12.5%, 0% and 22.5% respectively.
3. Serological identification of isolated E.coli:
The seriological serotypes of E.coli from the examined street-vended samples were O86:K61, O55: K59, O111: K58, and O114:K90 and untypable.
4. Experimental study:
4.1. Effect of yoghurt processing and storage on survival of Enteropathogenic E.coli.
The number of E.coli declines continuously during refrigerated storage of yoghurt, significant number may still exist in the yoghurt after 9th day 1.79x10±1.50x10.This is great concern considering the expiry date of yoghurt is typically set to be after 15 days.
4.2. Effect of freezing on survival of Enteropathogenic E.coli in Ice cream stored at -4 and -18ºC.
The number of E.coli decrease gradually to reach 2.13x103± 6.26x102 and 7.94x102±1.23x10 with reduction percent of 93.54 and 97.59, respectively by the end of 35th day of storage. This is great concern considering the expiry date of ice cream is typically set to be after 35 days.
4.3. Effect of Enteropathogenic E.coli in Kareish cheese during processing and storage at 4 ± 1ºC.
A gradual reduction in counts to reach minimum count of 2.12x10±1.23x10 by the end 21st of refrigeration storage before the complete reduction occurred at 28th day of storage. This is great concern considering the expiry date of Kareish cheese is typically set to be after 28 days of manufacture.
4.4. Effect of different concentration of Sodium chloride on viability of E.coli in Damietta cheese, stored at room and refrigeration temperature.
There was steady decrease in in numbers of E.coli during storage at 30˚C of Damietta cheese samples containing 5% and 10% salt to minimum counts of 1.2x104± 5x102 and 2.0x103±10x102/g by the end of the storage period with reduction percent of 99.97 and 99.98, respectively.
Continuous reduction in E.coli counts in Damietta cheese containing 5 and 10% salt during storage period at refrigeration temperature 4+1˚C with 99.99% for both concentrations. This is great concern considering the expiry date of Damietta cheese typically set to be after 8 weeks of manufacture.
4.5. Survival of S.aureus in Kareish cheese during processing and storage at 4 ± 1ºC.
A gradual decrease in S.aureus to reach minimum count of 2.35x102 ±2.0x10 cfu/g by the end of 21st of refrigeration storage before the complete reduction occurred at 28th day of storage.
4.6. Effect of different concentration of Sodium chloride on viability of Staphylococcus aureus in Damietta cheese, stored at room and refrigeration temperature.
A gradual reduction in S.aureus count reached a minimum count of 3.2x103± 5.1x102 and 2x103±10x102 cfu/g by the end of storage period with reduction percent of 70.54 and 99.44, respectively.
A sharply decrease in S.aureus count in Damietta cheese samples containing 5 and 10% NaCl during storage period at 4+2˚C.the reduction percent were 99.94 and 99.99, respectively.
4.7. Effect of yoghurt processing and storage on storage of Aeromonas hyDROPhila.
A gradual decrease in count to complete reduction at 4th day of storage. These mean that the increased acidity has a great inhibitory effect on viability of Aeromonas hyDROPhila.
4.8. Effect of different concentration of Sodium chloride on viability of Aeromonas hyDROPhila in Damietta cheese, stored at room and refrigeration temperature.
Aeromonas counts decrease gradually to reach minimum count of 2.50x10±9.0x10 and 7.95x10±6.04x10 with reduction percent of 98.25 and 100, respectively by the end of 8th week and 6th week of storage, respectively.
A continuous reduction in Aeromonas hyDROPhila in Damietta cheese containing 5 and 10% salt concentration during the manufacture and storage period at refrigeration temperature with 100% by the end of 5th and 3rd week of storage.