الفهرس 
المقدمةOnly 14 pages are availabe for public view
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Abstract
Yeasts are distinguished by their wide variety of technological properties and industrial
applications. Their presence in the foodstuff ranges from acceptable (as starter cultures or as probiotic microorganisms) to rejected (food spoilage causative microorganisms). Milk and milk
products are suitable for the growth of many yeasts. The microbiological characterization of Egyptian dairy products suffers from the lack of studies related to studying the diversity of yeasts and evaluating their technological, functional, and biological properties in addition to
safety issues related to their application. Therefore, the aim of this study was to isolate some of the yeasts commonly found in Egyptian dairy products to assess the prevalence of yeasts in milk and its products, to evaluate their technological, safety and probiotic properties, and also their ability to produce ethanol.
This study began by collecting a number of samples of milk and dairy products from the various governorates of the Arab Republic of Egypt. in addition, some raw milk samples were also collected from the Sudanese city of Khartoum. This was in order to obtain yeast isolates with diverse phenotypic and genotypic characteristics. A number of 517 isolates of yeasts were isolated from 83 samples of traditional dairy products. These isolates were subjected to a series of tests to assess their technological and functional properties, and 36 isolates were selected to assess their bio-stimulating properties, and their ability to produce ethanol and grow in sweet t. Five isolates were identified at the species level, by genetic technique, as they were distinctive in their technological and functional characteristics and ethanol production. This study included four sets of experiments as follows:
First set of experiments: technological characteristics
The ability of yeast isolates (517 isolates) to hydrolyze milk protein, lipid, starch and to ferment sugars (glucose, lactose) was evaluated during this set of experiments. Also, isolates
were evaluated for their ability to tolerate ethanol, salt, pH in addition to the appropriate temperature estimate for each of them. The results indicated the following:
61 • Among isolates, 94 demonstrated different capabilities of protein hydrolysis. In addition, 106 isolates had the ability to hydrolyze lipid and 74 isolates had the ability to hydrolyze starch.