Thesis (M.Sc.) - Cairo University - Faculty of Agriculture - Department of Microbiology

Fresh juices are one of the best ways to supply the body with nutrients, because of their highly content of minerals and vitamins. They widely consumed on a large scale by millions of people, and as such juices are of common consumption and are highly susceptible to spoilage, so it is important from public health point of view to evaluate physical, chemical, and microbial characteristics of such fresh juices. The present study aims to determine total bacterial counts, total coliforms, fecal coliforms, total fungi, total yeast, total spore forming bacteria as well as the determination of E. coli O157:H7 and S. aureus in common Egyptian fresh juices (sugarcane, strawberry, orange, guava, banana, cocktail, carrot, mango, sobia, and tamarind) where the juice samples under study assembly during the winter and summer seasons throughout one year. During this study 259 bacterial strains (159 E. coli O157:H7 and 100 S. aureus) were isolated from different Egyptian fresh juices. The highest total viable bacterial count (6.2 log cfu/ml) was found in carrot sample, and the lowest (2.5 log cfu/ml) was found in sobia sample in winter, while in summer, cocktail recorded the highest total count (7.29 log cfu/ml) and the lowest one (5.21 log cfu/ml) was found in banana juice. E. coli O157:H7 isolates were identified using classical as well as molecular diagnosis methods. Out of 159 isolated E. coli O157:H7 strains, 23 isolates were subjected to PCR analysis as molecular confirmation for the presence of E. coli O157:H7 using specific primers to shiga toxins (stx1 and stx2) and haemolysin gene (hlyA).

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