الفهرس 
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Abstract
The present study was conducted to investigate the bacterial quality of 150 samples of beef edible by-products, which included 40 samples of each lung, tripe, intestine and 30 brain samples. Samples were collected from different retail butcher shops in Assiut city.
Total bacterial count (T.B.C.) of examined beef edible by-product samples were ranged from 3.2 to 7. 4 log CFU/g, while mean values were ranged from 4.88 to 5.3 log CFU/g, where mean values of lung, tripe, intestine and brain were 5.01+0.79, 5.3+0.89, 5.06+0.89 and 4.88+1.06 log CFU/g, respectively.
Total coliform count of examined edible beef by-product samples included only 3 samples <3.0 MPN/g (2%) and 38 samples were >1100 MPN/g (25.3%), while there were 15 samples ranged from 3 - <10 MPN/g (10%), and 42 samples were between 10- <102 (28%), but there were 52 samples in range of 102- <1100 (34.7%). Most of samples which recorded number of coliform >1100 MPN/g were tripe and intestine samples (14 and 15 samples, respectively). The mean values of the samples which recorded number between 3 to 1100 MPN/g were ranged from 225.5 to 406.9 MPN/g, where the mean values of lung, tripe, intestine and brain were 229.13+347.83, 332.58+335.09, 406.88+430.52 and 225.5+354.86 MPN/g, respectively.
Regarding B. cereus, out of 150 examined beef edible by-products samples, 12 samples (8%) were positive, which included 5 samples of tripe, 4 samples of intestine and 3 samples of brain, while lung samples were free. The average count of B. cereus in positive samples was 1.6x103 CFU/g, where average number in tripe, intestine and brain were 3x103, 1.4x103 and 5x102 CFU/g, respectively. These values were below the pathogenic number of B. cereus which estimated as 104 CFU/g.
Concerning Salmonella spp., 4 samples (2.7%) only from the total 150 examined samples of beef edible by-products were positive for Salmonella spp., which included one sample of intestine and three samples of lung. Isolated species were S. anatum, S. Typhimurium and S. Enteritidis.
Three organic acids (acetic, lactic and citric acids) were tested for their antibacterial activity against isolated bacteria (B. cereus, S. Typhimurium and S. Enteritidis) by agar well diffusion method and the average width of inhibition zones were 22, 20 and 32 mm for acetic acid, 15, 16 and 22 mm for lactic acid and 17, 16 and 23 for citric acid against B. cereus, S. Typhimurium and S. Enteritidis, respectively. from these obtained results, it could be concluded that acetic acid was the most effective antibacterial against the isolated bacteria in the present study.
Also, minimum inhibitory concentration (MIC) of these organic acids were determined against the isolated bacteria and found that the MIC of acetic acid were 0.3%, 0.3% and 0.2%, of lactic acid were 0.4%, 0.3% and 0.4 % and of citric acid were 0.8%, 0.4% and 0.3% against B. cereus, S. Typhimurium and S. Enteritidis, respectively.