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Abstract
Summary
A total of 120 meat product samples were collected randomly from different supermarkets in Assiut city. These samples included beefburger, luncheon and sausage (40 of each). All samples were subjected to: organoleptic examination, measuring the histamine contents by using high performance liquid chromatography (HPLC), identification the microbial flora with histidine decarboxylase activity and detection of histidine decarboxylase activity of isolated organisms on Niven modified medium. The obtained results revealed the following:
1. Organoleptic examination:
All the examined samples showed good technical properties from the aspect of forming and binding. In addition, all samples have acceptable odor (fleshy& spicy). The red color was predominating and found in 90, 85 and 100% of the examined beefburger, luncheon and sausage samples, respectively. Moreover, comminution varied between coarse in 12.5 and 37.5% and fine in 87.5 and 62.5% of examined beefburger and sausage samples, respectively.
2. Estimation of histamine:
The mean values of histamine in the examined beefburger, luncheon and sausage were 4.225 ± 0.663; 3.428 ± 0.516 and 5.121 ± 0.637mg/100g, respectively. The maximum histamine levels in examined samples were 11.433, 9.901 and 11.227mg/100g, while the minimum levels were 0.087, 0.045 and 0.169mg/100g, respectively. Most of the beefburger and luncheon samples (52.5% of each) had histamine content within the range of 0.0-<2.0mg/100g, whereas 42.5% of sausage samples lied within the range of 8.0-<10.0mg/100g. The high level of histamine was recorded in beefburger and sausage, while the lowest level was in luncheon.
3. Microbial analysis:
The mean Enterobacteriaceae count of the examined beefburger, luncheon and sausage were 3.85x104 ± 2x104, 6.3x103 ± 4.14x103 and 1.72x104 ± 3.65x103 cfu/g, respectively. The maximum Enterobacteriaceae count in the examined samples were 8x105, 1.42x105 and 7.8x104 cfu/g while the minimum count were 1.8x102, 1x10 and 5x10 cfu/g, respectively. 27.5% of meat product samples lied in the range of 104-<105 while, 3 samples (2.5%) had count over 105/g. Variations in the mean Enterobacteriaceae count between the different examined meat products were non significant.
Moreover 100, 25 and 100% of beefburger, luncheon and sausage samples contained Coliforms with high frequency distributions of 57.5, 75.0 and 62.5% lied within the range of >103, <3 and >103cfu/g, respectively. Faecal Coliforms recovered from 90, 22.5 and 92.5% of the examined sample, respectively. Most of these samples, 37.5, 77.5 and 32.5% had faecal Coliforms ranged from 10-<102, <3 and 102-<103cfu/g, respectively.
The gained results proved that E. coli were detected in 72.5, 2.5 and 75.0% of beefburger, luncheon and sausage samples, respectively. Most of beefburger and sausage samples had E. coli ranging from 10-<102 and
3-<10cfu/g, respectively.
Regarding Pseudomonas count, the mean values of the tested meat products were 8.7x103 ± 4.3x103, 2.05x102 ± 2x102and
2.19x103 ± 6.57x102cfu/g, respectively, and 44.16% had count within the range of <102cfu/g. A significant difference in the mean was noticed between sausage and luncheon samples.
Members of Enterobacteriaceae including: Arizona spp. (1.67%), Citrobacter diversus (1.67%), C. freundii (15%), Enterobacter aerogenes (2.5%), E. cloacae (60%), E. gergoviae (0.83%), Escherichia coli (49.16%), Klebsiella oxytoca (16.6%), K. ozaenae (0.83%), K. pneumoniae (47.5%), Morganella morganii (0.83%), Pantae agglomerans (3.33%), Proteus mirabilis (5.0%), P. vulgaris (1.67%), Providencia alcalifaciens (0.83%), Salmonella spp. (7.5%), Serratia liquefaciens (5.0%),
S. marcescens (6.66%), S. rubidaea (1.67%) and Shigella sonnei (2.5%) were recovered from the examined samples. Furthermore, Pseudomonas alcaligenes, P. cepacia, P. diminuta, P. fluorescens, P. maltophilia,
P. pickettii, P. putida, P. putrefaciens, P. stutzeri and P. vesicularis were existed in 7.5, 6.67, 5.0, 35.83, 9.17, 11.67, 9.17, 4.17, 13.33 and 1.67% out of 120 examined meat product samples, respectively.
4. Detection of histidine decarboxylase activity of the isolated organisms:
55.47, 65.52 and 57.89% of Enterobacteriaceae strains recovered from beefburger, luncheon and sausage were histamine producers on Niven modified medium, respectively. whereas, 29.7% of isolates of beefburger were decarboxylase positive after 24 h. Enterobacter aerogenes,
Pantae agglomerans and Serratia rubidaea constituted the highest percentage (100%), while Enterobacter cloacae, Klebsiella oxytoca,
K. pneumoniae, Serratia liquefaciens and S. marcescens were histamine producers at variable percentages ranging from 20.0 to 85.7%. Also, 15.63 and 10.16% of beefburger strains were histamine producers after 48 and
72 h of incubation, respectively with percentages ranging from 4.76 to 100%.
19 (65.52%) out of 29 Enterobacteriaceae strains of luncheon samples were histamine formers. 26.67 and 66.67% of E. cloacae and
K. pneumoniae were decarboxylase positive after 24 h, respectively. whereas, 40 and 22.22% of isolated E. cloacae and K. pneumoniae were histamine producers after 48 h respectively and only one strain of
E. cloacae after 72 h of incubation.
54 strains isolated from sausage samples were decarboxylase positive after 24 h of incubation. E. aerogenes and M. morganii constituted the highest percentage (100%), while C. freundii, E. cloacae, Escherichia coli,
K. oxytoca, K. pneumoniae, Pantae agglomerans, S. liquefaciens and
S. marscence were histamine producers at variable percentages ranging from 2.63 to 88.9%.
In case of sausage, 12.03 and 5.26% of isolated strains were histamine producers after 48 and 72 h of incubation, respectively with incidences ranging from 7.4 to 100%.
72.0, 75.0 and 70.3% of isolated Pseudomonas strains from beefburger, luncheon and sausage were histamine formers on Niven modified medium, respectively.
24.56% of strains isolated from beefburger were decarboxylase positive after 24 h with rates between 25 to 40%. While, 19.3 and 28.07% of the tested strains were histamine producers after 48 and 72 h of incubation on Niven modified medium, respectively with levels lied between 10.0 to 66.67%.
As regarding luncheon samples, 3 (75%) out of 4 isolated strains were histamine formers. P. fluorescens, P. cepacia and P. pickettii constituted the highest percentage (100%) after 24, 48 and 72 h of incubation, respectively.
15.63% of strains isolated from sausage were decarboxylase positive after 24 h of incubation including 36.36 and 18.18% of P. fluorescens and P. stutzeri, respectively. While, 34.38 and 20.31% of tested isolates were histamine producers after 48 and 72 h of incubation on Niven modified medium, respectively with incidences ranged between 18.18 to 66.67%.
Antimicrobial activity of spices extracts:
The present study was conducted to examine the inhibitory effect of 5 extracts namely garlic, ginger, nigella, oregano and thyme on the growth of seven pathogenic bacteria. Two different procedures were carried out to test the bacteriostatic and bactericidal effect of these spice extracts, which include agar diffusion method and broth dilution method using different spice extract concentrations. The inhibitory effect of various microorganisms indicated that ginger, nigella, oregano and thyme had no or very little effect against the examined microorganisms. While at the other extreme garlic was highly active against all of tested bacteria. The MIC by the agar diffusion and broth dilution methods of garlic were 2.51, 1.56; 1.78, 0.78; 2.51, 0.4; 2.51, 0.78; 1.99, 0.4; 2.51, 0.78 and 2.51, 0.4%, respectively against E. aerogenes, E. cloacae, E. coli O157:H7,
K. pneumoniae, M. morganii, P. fluorescence and S. typhimurium. whereas, the MLC of garlic was 1.56, 1.56, 0.78, 1.56, 0.4, 1.56 and 0.78%, respectively. Also, the effect of different garlic concentrations 0.2, 0.4, 0.8 and 1.56% were used against E. coli O157:H7 and S. typhimurium using minced meat stored at 4ºC for 4 days. Highly significant differences between the control and the treated samples at P< 0.05 were recorded and S. tyhimurium counts were reduced by using of higher concentrations of garlic than lower concentrations.