الفهرس 
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Abstract
Milk is a highly nutritious food, ideal for microbiological growth because of its high water content, near neutral pH and variety of available nutrients. Psychrotrophs seem to become the newest thorn in dairy industry which are inactivated by pasteurization temperature. But, they produce thermoresistant proteolytic and lipolytic enzymes which can degrade the important component of milk. Consequently, a qualitative risk during milk processing and cause the spoilage of final products during storage. A total of 150 random samples of raw milk and some dairy products were collected for chemical, sanitary and bacteriological examination. The mean value of fat%, acidity % and pH was (3.58±0.16, 4.72±0.21, 3.55±0.41, 3.27±0.69 and 3.9±0.22%), (0.16±0.00, 0.17±0.00, 0.31±0.05, 0.13±0.01 and 1.13±0.02%) and (6.70±0.04, 6.76±0.02, 5.96±0.07, 6.54±0.05 and 4.48±0.06) for farm raw milk, market raw milk, small scale ice cream, large scale ice cream and commercial plain yoghurt samples, respectively. The mean value of total bacterial count TBC was (5.4×105 ± 1.23, 1.8×108 ± 1.31, 1.3×105 ± 1.4 and 6.7×102 ± 1.6 cfu/ml) for farm raw milk, market raw milk, small scale ice cream and large scale ice cream samples, respectively. The mean value of total psychrotrophic count and Pseudomonas count was (7.2×104 ± 1.28, 3.3×107 ± 1.34, 7.9×103 ± 1.3, 2.1×102 ± 1.38 and 1.3×105 ± 1.41 cfu/ml), (2.8×104 ± 1.23, 1.7×107 ± 1.31, 2.8×103 ± 1.44, 1×102 ± 1.41and 5×104 ± 1.41cfu/ml) for farm raw milk, market raw milk, small scale ice cream, large scale ice cream and commercial plain yoghurt, respectively. Also, Identification of Pseudomonas isolates was carried out on bases of morphological, cultural and biochemical characteristics. Further phenotypic characterization was conducted using API20NE identification kits. Ps. fluorescens is the most prominent Pseudomonas spp. in raw milk and its products which causes spoilage of milk and dairy products due to the action of extracellular heat resistant lipases and proteinases.