الفهرس 
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Abstract
Ninety samples of nine vacuum-packed meat products (ten of each) produced by two factories were collected from different wholesale retail outlets at Cairo and Giza Governorates as follows: Factory 1: Frankfurter ”A”, Salamy ”A”, Beef meat ”Gahez” and Beef meat ”Cooked” and Factory 2: Frankfurter ”B”, Salamy ”B”, Beef bacon, Rose beef and Luncheon.
Regarding the organoleptic examination all samples of frankfurter
”A” and ”B” , salamy ”A” and ”B”, beef meat ”Gahez” and ”Cooked”, and rose beef were accepted having normal color, odor and texture with mean storage periods of 24, 19, 27, 40, 20, 27 and 20 days. Meanwhile only 90% of luncheon and beef bacon samples were accepted with mean storage periods of 35 and 36 days.
Mean pH values ± SE of frankfurter ”A” frankfurter ”B” salamy
”A”salamy ”B” beef meat ”Gahez”, beef meat ”Cooked”, rose beef, luncheon and beef bacon were: 5.66 + 0.02; 5.58 + 0.02, 5.68 ± 0.02, 5.8 + 0.04, 5.89 ± 0.03, 5.97 ± 0.07, 5.58 + 0.02, 5.62 0.03 and 5.71 ± 0.11, respectively.
The mean aerobic plate count (APC) of frankfurter ”A” (1.2 X 108 ± 5.6 X 107) was significantly higher (P < 0.05) than that of frankfurter
”B”(7.6 X 107 ± 2.5 X 107), and for salamy ”A” the mean count was (1.2 X 108 ±2.2 X107) was significantly lower (P < 0.05) than that of salamy
”B” (5.3 X 108 ± 1.1 X 108). On the other hand the mean APC count of beef meat ”Gahez”, beef meat ”Cooked”, rose beef, luncheon and beef bacon were 4.0 X 107+ 1.8 X 107, 3.3 X 107+ 1.6 X 107, 1.7 X 108+ 3.7 X 107, 2.9 X 108± 8.6 X 107and 2.5 X 108+ 1.1 X 108, respectively.
Similarly the mean psychrotrophic count of frankfurter ”A” (1.8 X 108 + 7.4 X 10’) was significantly lower (P < 0.05) than that of frankfurter ”B” (8.0 X 10’ ± 2.2 X 10’), and for salamy ”A” the mean count (2.8 X 108 ± 6.1 X 1 07) was significantly higher (P < 0.05) than that of salamy ”B” (6.3 X 108 ± 1.0 X 108). On the other hand the mean psychrotrophic count of beef meat ”Gahez”, beef meat ”Cooked”, rose beef, luncheon and beef bacon were 7.5 X 107+ 3.7 X 107, 5.2 X 107+1.8 X 107, 3.5 X 108 +6.6 X 107, 3.4 X 108 +7.0 X 107 and 2.5 X 108+9.9 X 107, respectively. Concerning lactic acid bacteria count the mean of frankfurter ”A” (1.4 X 108 ± 6.9 X 1 07) was significantly higher (P < 0.05) than that of frankfurter ”B” (1.1 X 108 ± 3.1 X 107), and for salamy ”A” the mean count (1.3 X 108 ± 2.9 X 107) was significantly lower (P < 0.05) than that of salamy ”B” (6.6 X 108+ 1.2 X 108). On the other hand the mean lactic acid bacteria count of beef meat ”Gahez”, beef meat ”Cooked”, rose beef, luncheon and beef bacon were 4.6 X 107 ± 2.0 X 107, 3.6 X 107 +1.9 X 107, 2.7 X 108+4.6 X 1 07,3.0 X 1 08+6.4 X 107 and 1.2 X 108± 2.5 X 107, respectively. Also for anaerobic count the mean of frankfurter ”A” (1.2 X 108 ± 6.1 X 1 07) was significantly higher (P < 0.05) than that of frankfurter ”B” (6.1 X 107 ± 1.9 X 107), and for salamy ”A” the mean count (1.2 X 108+ 2.5 X 1 07) was significantly lower (P < 0.05) than that of salamy ”B” (3.8 X 108 ± 9.1 X 107). On the other hand the mean anaerobic count of beef meat ”Gahez”, beef meat ”Cooked”, rose beef, luncheon and beef bacon were 2.7 X 107+ 1.4 X 107, 3.2 X 107+1.7 X 107, 1.3 X 108+ 1.8 X 107, 2.8 X 108 ± 5.0 X 107 and 1.3 X 1 08+4.3 X 107, respectively.
On the other hand the mean count of B. thermosphacta count for frankfurter ”A” (3.6 X 102 ± 6.7 X 10) was significantly higher (P < 0.05) than that of frankfurter ”B” (2.5 X 102 ± 7 X 10), and for salamy ”A” the
mean count (3.1 X 102 ± 7 X 10) was significantly higher (P < 0.05) than that of salamy ”B” (2.7 X 102+ 6.2 X 10). On the other hand the mean B. thermosphacta count of beef meat ”Gahez”, beef meat ”Cooked”, rose beef, luncheon and beef bacon were 3.7 X 102+ 9.2 X 10, 2.9 X 102± 1.9 X 102, 9.0 X 10 ± 1.1 X 10, 4.3 X 102+ 1.5 X 102 and 7.0 X 102+ 2.3 X 102, respectively.
There was a good correlation coefficient between aerobic, psychrotrophic, lactic acid bacteria and anaerobic count. Meanwhile there was no correlation between B. thermosphacta count and any of the other bacterial count.
The mean anaerobic sporeformers count of frankfurter ”A”, frankfurter ”B”, salamy ”A”, salamy ”B”, beef meat ”Gahez”, beef meat ”Cooked”, rose beef, luncheon and beef bacon were 7.0 X 10 ± 4.7 X 10, 5.0 X 10 ± 3.4 X 10, 4.0 X 10 ± 4.0 X 10, 4.0 X 10 ±4.0 X 10, 1.5 X 10 ± 1.5 X 10, 2.0 X 10 ± 2.0 X 10,2.0 X 10 ± 2.0 X 10, 1.4 X 102+7.9X 10 and 4.0 X 10 +3.1 X 10, respectively.
The study failed to isolate any of the following pathogenic microorganisms; Listeria monocytogenes, Staphylococcus aureus, Bacillus cereus or any of the Clostridium spp. of public health significance.
Concerning chemical analysis, the both of TVB-N and TBA remain in the accepted level, while no correlation was found between their levels and the bacterial count of the samples. On the other hand all samples contained nitrite levels within the permissible limit.
Five trials for prolonging of shelf life were adopted on experimentally manufactured frankfurter samples. frankfurter mixture was divided into 2 parts, the first was stuffed and cooked while 2% sodium lactate was added to the second. Both parts were divided into 3 groups after cooking and peeling the first was packed directly, the second was dipped into 5% sodium sorbate solution and the third was in-pack pasteurized in the second day of packing Analysis of variance between the different groups indicated that all treatments significantly (P<0.5) increased the shelf life (based on bacterial count of 108 cfu/g) of the manufactured samples than the control one (group 1). For group 1 the shelf life was less than 4 weeks. Meanwhile, the shelf life reached 5 weeks for each of groups 2, 4 and 5, moreover, pasteurization (groups 3 and 6) increased the shelf life another week to reach 6 weeks.
The sensory properties still accepted in all groups even in those where the bacterial counts exceeded 108 cfidg, the result, which indicate the week correlation between bacterial counts and organoleptic characters and ensure that the predominant lactic acid bacteria have the lowest effect on the sensory properties of meat products.
There was a good correlation between different bacterial counts allover the storage period except for B.thermosphacta count. The result, which indicated that lactic acid bacteria predominate the microflora in vacuum-packed meat products