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Abstract
SUMMARY
Two hundred random samples of dairy desserts consists of Mehallabeia, Rice with milk, small scale produced ice cream and large scale produced ice cream, (50 samples each) were collected from different dairy shops, primitive restaurants and supermarkets in Assiut City.
Our current results indicated that the aerobic plate count ranged from 1 X 103 to 9 x 106 with an average count of 3.9 x 105 / g of mehallabeia samples. Most of the examined samples (42 %) had count ranged from 104 to < 105 / g while, 8 % of samples exceeded 106 / g. Psychrotrophic count ranged from < 100 to 4.2 X 104 with an average count of 9.4 X 103 / g. It is worth to notice that most of positive samples, 38 in a percentage of 95 % contained psychrotrophs within the range of 103 to < 105. Coliforms could be detected in 37(74 %) out of 50 examined mehallabeia samples and the majority of positive samples (56.76%) had counts lie in between 103 to < 104 / g. Also, 32% of samples were contaminated with fecal coliforms with highest frequency distribution of 43.75 % (less than 10 / g). E. coli could be isolated from 4 % of the examined samples. Enterococci were isolated from 68 % of samples with a minimum of < 100 and a maximum of 1.1 X 105 and an average of 5.1 X 103 / g. The highest frequency distribution (44.12 %) lies in between 103 to < 104. 92 % of examined samples were contaminated with yeasts and molds and the level of contamination varied from < 10 to 7.3 X 104 with an average count of 6.6 X 103 / g. Most of positive samples (45.65 %) lies within the range of 103 to < 104 / g.
Regarding rice with milk, the results revealed that the aerobic plate count ranged from < 100 to 8 X 105 with an average count of 4.3 X 104 / g, most of positive samples (48 %) lies within the range of 104 to < 105. Psychrotrophes were detected in 82 % of samples at level varied from < 100 to 1 X 105 with an average of 1.1 X 104 / g and 43.9 % of positive samples ranged from 104 to < 105. Most Probable Number (MPN) technique showed that 54 % of the examined samples had coliforms in variant numbers. The highest frequency distribution was found within the range of 103 to < 104. Also, 34 % of samples were contaminated with fecal coliforms and the majority of positive samples (47.06 %) were less than 10/ g. However, E. coli could not be isolated from any of examined samples. Enterococci were existed in numbers varied from < 100 to 6.2 X 105 with an average count of 2.2 X 104 / g. The majority of positive samples (68.58 %) had counts of 103 to < 105. While, 94 % of this product were contaminated with total yeasts and molds. The highest level of frequency distribution (61.7%) lies within the range of 103 to < 104 / g.
Concerning ice cream samples collected from small scale produced, it is found that the aerobic plate count ranged from 1 X 103 to 6 X 106 with an average of 1.9 X 105 bacteria/ ml. Most of the examined samples (58 %) had counts ranged from 104 to < 105, while only 2 % of the samples had numbers exceeded 106/ ml. Psychrotrophs isolated from 88 % of the examined samples in numbers varied from <100 to 3 X 105 with an average count of 3 X 104/ ml. The majority of positive samples (59.09 %) had counts ranged from 104 to < 105/ ml. Most Probable Number (MPN) technique pinpointed that 96, 92 and 20 % of the positive samples were contaminated with coliforms, fecal coliforms and E. coli, respectively. The highest frequency distribution of the corresponding organisms, 58.32, 34.78 and 70 % lies in between the range of 103 to < 104, 103 to < 104 and 10 to < 102, respectively. 62 % of samples were contaminated with enterococci in counts varied from < 100 to 1.2 X 105 with an average of 1 X 104/ ml. The highest frequency distribution (48.39 %) and the lowest one (3.23 %) of positive samples had counts lies within the range of 104 to < 105/ ml and > 105/ ml, respectively. Furthermore, total yeasts and molds were existed in all examined samples in numbers ranged from 1 X 103 to 1.1 X 105 with an average of 2.3 X 104 and the majority of positive samples (26 %) had counts ranged from 104 to < 105.
In case of large scale ice cream, the average count of aerobic bacteria was 1.5 X 103 and the majority of positive samples (56%) found between the range of 102 to < 103, while 4 % of samples had total counts less than 100 / ml. Psychrotrophic bacteria were found in numbers varied from < 100 to 8 X 10 3 with an average of 6.7 X 102 and the frequency distribution showed that 55.55 and 44.45 % of the samples had counts ranged from 102 to < 103 and 103 to < 104, respectively. Coliforms organisms could be detected in 30 % of the examined samples and the majority of the positive samples (46.67%) lie within the range of 10 to < 102. Also, fecal coliforms could be isolated from 18 % and the highest frequency distribution (77.78 %) was less than 10 / ml. While, E. coli failed to be isolated. Enterococci organisms were detected in 60 % of the examined samples at level of contamination varied from < 100 to 4 x 104 with an average of 3.2 X 103. Almostly, all of the positive large scale samples had counts ranged from 102 to < 103/ ml. Yeasts and molds were detected in 88% of the examined samples in counts ranged from < 10 to 2 X 103 with an average of 1.9 X 102 / ml. The highest frequency distribution (63.64 %) lies within the range of 10 to < 102.
Fortunately, it is found that 96 % of the examined samples were in order with the permissible limits of foreign standards for total aerobic plate count / ml.
Recommendations were suggested to control the presence of such organisms in the evaluated milk products to avoid their undesirable changes that resulted in public health hazard.