الفهرس 
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Abstract
Microbiological criteria are a useful way to determine the safety and quality of meat products. Many different types of microorganisms present in or on meat products, can be used in the estimation of their microbiological safety and quality. The present study has been conducted on two parts. The first part has discussed the microbiological criteria of some meat products, while the second part has discussed the antibacterial effect of some essential oils on Yersinia enterocoiltica inoculated into minced meat kept at 4˚C. In the first part, two hundred of meat product samples ( Beef burger, Luncheon, Pasterma and Sausage) were collected from different retail shops at Alexandria province. The samples were examined microbiologically for their microbiological criteria. And the obtained results revealed the following: A. Enumeration results: A.1. Aerobic plate count. The results show that the incidence of Aerobic bacteria was 100% in all examined meat products (Beef burger, Luncheon, Pasterma and Sausage). In beef burger samples, the total Aerobic bacterial count ranged from 9.0 X 10 to 4.39 X 103 with a mean value of 8.20 X 102 ± 0.19 X 10. Luncheon ranged from 2.0 X 10 to 3.71 X 103 with a mean value of 6.29 X 102 ± 0.16 X 10. Pasterma ranged from 9.0 X 10 to 3.30 X 103 with a mean value of 5.40 X 102 ± 0.13 X 10. Sausage ranged from 3.0 X 10 to 4.72 X 103 with a mean value of 8.28 X 102 ± 0.18 X 10 cfu/g, respectively. A.2. Psychotrophic bacterial count. The results of the total Psychotrophic bacterial count of the examined meat products samples were, in beef burger ranged from 2.0 X 10 to 3.29 X 103 with a mean value of 5.57 X 102 ± 0.47 X 10. Luncheon ranged from 5.0 X 10 to 3.66 X 103 with a mean value of 4.96 X 102 ± 0.36 X 10. Pasterma ranged from 2.2 X 10 to 3.43 X 103 with a mean value of 5.83 X 102 ± 0.51 X 10 and at last sausage ranged from 1.2 X 10 to 3.71 X 103 with a mean value of 7.64 X 102 ± 0.76 X 10 cfu/g respectively. A.3. Enterobactericeae count. the total Enterobactericeae count of examined meat products samples, was ranged from 7.0 X 10 to 3.83 X 103 with a mean value of 5.27 X 102 ± 1.52 X 10 in beef burger. In luncheon ranged from 4.0 X 10 to 3.62 X 103 with a mean value of 4.65 X 102 ± 1.43 X 10 while pasterma ranged from 3.0 X 10 to 4.49 X 103 with a mean value of 3.74 X 102 ± 1.34 X 10 while sausage ranged from 1.0 X 10 to 3.20 X 103 with a mean value of 7.47 X 102 ± 1.61 X 10 cfu/g respectively. A.4. Coliforms count. The results of the total Coliforms count of examined meat products samples were, in beef burger ranged from 9.0 X 10 to 1.98 X 103 with a mean value of 2.92 X 102 ± 0.82 X 10, luncheon ranged from 4.0 X 10 to 3.71 X 103 with a mean value of 3.50 X 102 ± 1.30 X 10, pasterma ranged from 1.0 X 10 to 4.84 X 103 with a mean value of 4.19 X 102 ± 1.52 X 10 and finally sausage ranged from 2.0 X 10 to 3.84 X 103 with a mean value of 7.64 X 102 ± 1.79 X 10 cfu/g respectively. A.5. Mold and Yeast count. The results of the total Yeast and Molds count of examined meat products samples were, in beef burger ranged from 1.0 X 10 to 6.40 X 103 with a mean value of 0.47 X 102 ± 0.17 X 10, luncheon ranged from 4.0 X 10 to 1.71 X 104 with a mean value of 1.21X 102 ± 0.52 X 10, patserma ranged from 2.0 X 10 to 1.47 X 104 with a mean value of 1.22 X 102 ± 0.49 X 10, while in sausage ranged from 1.0 X 10 to 9.70 X 103 with a mean value of 1.0 X 102 ± 0.33 X 10 cfu/g respectively. While the incidence of identified Mold isolated from examined beef burger, luncheon, pasterma and sausage were (68, 66,68 and 80%) for Aspergillus flavus, (20, 0, 26 and 66) for Aspergillus fumigates, (34, 26, 20 and 0%) for Aspergillus fusarium, (0, 0, 14 and 8%) for Aspergillus nidulans, (66, 74, 40 and 74%), for Aspergillus niger, (6, 14, 0 and 20%) for Aspergillus ochraceus, ( 6, 6, 0 and 8%) for Aspergillus terreus, (0, 6, 0 and 0%) for Mucor spp., (8, 26, 0 and 0%) for Penicillium spp. and (6, 6, 0 and 26%) for Rhizopus spp. respectively. On the other hand, the incidence of identified Yeast isolated from examined beef burger, luncheon, pasterma and sausage were (26, 26, 14 and 26%) for Candida albicans, (0, 0, 6 and 0%) for Candida kruesi, (0, 0, 13 and 0%) for Candida neaformans, (0, 6, 0 and 0%) for Candida tropicalis, (6, 0, 0 and 28%) for Cryptococcus spp., (0, 0, 14 and 20%) for Rhodotorula spp. and (6, 12, 20 and 0%) for Saccharomyces cerevisiae. B. Isolation and Identification of some pathogenic bacteria: B.1. Isolation and Identification of Staphylococcus aureus. the incidence of positive coagulase Staphylococcus aureus isolated from examined meat products samples (Beef burger, luncheon, pasterma and sausage) was 68, 80, 60 and 88%, respectively. B.2. Isolation and identification of Salmonellae. The incidence of identified Salmonella spp. isolated from meat product samples (Beef burger, luncheon, pasterma and sausage) as it was 20, 26, 6 and 40%, respectively. The isolated serotypes of Salmonella spp. from examined beef burger, luncheon, pasterma and sausage were (2, 4, 0 and 4%) for Salmonella Enteritidis, (4, 6, 0 and 6%) for Salmonella Paratyphi, (6, 8, 4 and 18%) for Salmonella Typhi and (8, 8, 2 and 12%) for Salmonella Typhimurium. B.3. Isolation and identification of Yersinia enterocolitica. The incidence of identified Yersinia enterocolitica isolated from meat product samples (beef burger, luncheon, pasterma and sausage) as it was 46, 40, 54 and 34%, respectively. While the biotyping of Yersinia enterocolitica isolated from examined beef burger, luncheon, paster a and sausage were (10, 12, 16 and 16%) for biotype IA, (10, 6, 6 and 2%) for biotype IB, (4, 6, 4 and 2%) for biotype2, (6, 4, 6 and 4%) for biotype3, (4, 8, 4 and 2%) for biotype4 and (12, 4, 18 and 8%) for biotype5. In the second part, one kilogram of minced meat was divided into five groups. The first three groups were inoculated each of Clove oil, Cinnamon oil and Ginger oil with concentration 1%. The fourth group was inoculated with a mixture composed of Clove oil, Cinnamon oil and Ginger oil with concentration 0.5% for each one. While the fifth one was used as a control one. The results revealed showed the following: The changes started since the first hour after treatment with the previous mentioned essential oils, as it showed slightly increasing in Yersinia enterocolitica count in all treated groups till the 24 hours. Then obvious decreasing in Yersinia enterocolitica count to reach its minimum reduction at 48 hours for all treated groups while the control one revealed great decomposition. And then obvious gradual increasing in Yersinia enterocolitica count for all treated groups to reach its maximum at the sixth day and decomposition for the groups treated with Clove oil, Cinnamon oil and Ginger oil with concentration 1%. While the group treated with the mixture continued till the sixth days with high Yersinia enterocolitica count. - The reduction percentage of Yersinia enterocolitica due to using of Clove oil with 1% concentration which ranged from 60.8% to 56.8% during the first seven hours and decreased to reach 25.9% at 24 hours. While reach its maximum percent at 48 hours with 86.3%. - The Reduction percentage of Yersinia enterocolitica due to using of Cinnamon oil with 1% concentration which ranged from 63.6% to 64.8% during the first seven hours and decreased to reach 4.9% at 24 hours. While reach its maximum percent at 48 hours with 85.2%. - The reduction percentage of Yersinia enterocolitica due to using of Ginger oil with 1% concentration which ranged from 63.8% to 67.4% during the first seven hours and slightly increased to reach 68.7% at 24 hours. While reach its maximum percent at 48 hours with 75.3%. - The reduction percentage of Yersinia enterocolitica due to using a mixture of Clove, Cinammon and Ginger oils with 1.5 % concentration which was ranged from 75.3% to 59.5% during the first seven hours and increased to reach 72.3% at 24 hours. While reach its maximum percent at 48 hours with 79.3%. from the previous results, we conclude that all the treated groups reached its maximum reduction percent at the 48 hours. The higher reduction percent was for the group treated with 1% Clove oil. While the longest shelf life was achieved in the group treated with a mixture of clove, ginger, and Cinnamon oils with 1.5 % concentration. Finally, the plant essential oils are bactericidal against Yersinia enterocolitica that associated with foodborne outbreak and human illness. It was found that Yersinia enterocolitica has a great susceptibility to these essential oils in low concentrations.