الفهرس 
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Abstract
A total of six groups of fresh broiler carcasses randomly collected from different poultry shops at Alexandria province. After examination of an untreated samples, the samples were classified into six groups, each group was represented by their muscle samples which were dipped in acid solutions as follows. The 1st group was dipped in 1% lactic acid solution v/v for five min. The 2nd group was dipped in 2% lactic acid solution v/v for five min. The 3rd group was dipped in 1% acetic acid solution v/v for five min. The 4th group was dipped in 2% acetic acid solution v/v for five min. The 5th group was dipped in 1% mixture of lactic and acetic acids v/v for five min. The 6th group was dipped in 2% mixture of lactic and acetic acids v/v for five min. After dipping, samples were left to dry and packed in separate sterile polyethylene bags and stored in refrigerator at 4 - 6 °C until examined at different time intervals after 1, 2, 4, 6, 8, 10 and 12 days respectively.
Treatment with organic acids which resulted in a significant improvement of nearly all parameters over the control of three groups of samples from different beef carcasses. Such treatments exerted a significant antibacterial effect which is of public health to prolong the shelf life of carcasses on trial.
The results can be summarized as follows:
The recorded mean pH value was 5.75 ± 0.05 on control samples while on chilling periods after 1 day, 2 days, 4 days, 6 days, 8 days,10 days and12 days, the highest recorded mean values were at 12 days chilling as 6.6±0.05, 6.3±0.06, 6.6±0.04, 6.3±0.06, 6.5±0.04 and 6.3±0.05 for lactic acid (1 and 2%), acetic acid (1 and 2%) and mixture of lactic and acetic acids (1 and 2%), respectively.
The mean value of TVN was 4.5±0.06 mg/100g of untreated broiler samples but after treatment with 1% lactic acid, 1% acetic acid, 1% mixture of lactic and acetic acids, the mean values were increased slowly in an ascending rate till reached 17.5±0.06, 17.7±0.06 and 17.9±0.05 mg/100g after 10 days of storage but after 12 days of storage, the mean values of TVN reached 21.2±0.05, 21.3±0.06 and 20.8±0.04 mg/100g, respectively. Also, the TVN mg/100g of treated broiler samples with 2% lactic acid, 2% acetic acid and mixture of lactic and acetic acids increased more slowly in an ascending rate till reached 18.9±0.06, 19.5±0.06 and 19.0±0.05 mg/100g, respectively. The results increased as the storage time increased.
The mean value of the APC of examined untreated broiler samples was 1.60×105 ±1.92 ×102 cfu/g. While after treatment with 1% lactic acid, 1% acetic acid, 1% mixture of lactic and acetic acids the counts reduced to 1.2×104±1.81×102, 1.2×104±1.35×102, 0.9×104±2.05×102 cfu/g. respectively. After one day of storage at chilling condition. Then the mean values of treated broiler samples with 1%lactic acid, 1% acetic acid and1% mixture of acids increase slowly in an ascending rate till reached 1.0×105±8.8×102, 2.0×105±9.2×102, 1.7×105±8.6×102 cfu/g.at 12 days of chilling condition. After treatment with 1% lactic acid, 1%acetic acid, 1% mixture of lactic and acetic acids the mean of APC was reduced at a percentage of (92.50%, 92.50%, 94.37%), (91.87%, 91.37%, 92.06%), (88.75%, 88.13%, 90.13%), (86.25%, 85.00%, 86.25%), (80.62%, 79.37%, 82.50%), (75.63%, 70.62%, 77.50%) and (37.50%, 31.87%, 55.62%), respectively after 1, 2, 4, 6, 8, 10 and 12 days of storage at chilling condition.
The mean value of the psychrophilic count cfu/g of untreated samples was 5.80×105±1.83×102 cfu/g while after treatment with 1% lactic acid, 1% acetic acid, 1% mixture of lactic and acetic acids, the counts were reduced to 1.7×103 ± 1.72×102, 1.5×103 ± 1.85×102, 2.2×103 ± 1.83×102 cfu/g, respectively after one day of storage at chilling condition while the mean values of treated broiler samples with 1% lactic acid, 1% acetic acid and1% mixture of acids increase slowly in an ascending rate till reached 1.0×106±1.75×102, 1.2×106±1.52×102, 1.4×106±1.52×102 cfu/g at 12 days of chilling condition P <0.05. So, reduction percentage mainly indicates the total psychrophilic count above the permissible limit at 10, 12 days of chilling condition so mean value increasing in counts than control. After treatment with 1% lactic acid, 1% acetic acid, 1% mixture of lactic and acetic acids. The mean value of psychrophilic counts was reduced at a percentage of (97.08%, 97.41%, 96.20%), (96.03%, 96.20%, 95.68%), (92.75%, 94.48%, 93.96%), (87.58%, 88.10%, 91.55%), (60.34%, 67.24%, 63.79%), (87.10%, 61.20%, 55.10%) and (94.20%, 95.30%, 96.02%), respectively after 1, 2, 4, 6, 8, 10 and 12 days of storage at a chilling condition.
The mean values of Enterobacteriaceae count of examined untreated samples is 1.56×104±2.35×102, cfu/g while after treatment with 1% lactic acid, 1% acetic acid, 1% mixture of lactic and acetic acids. The counts reduced to 1.2×103 ± 1.81×102, 1.2×103 ± 1.88×102, 1.7×103 ± 1.41×102 cfu/g after one day of chilling condition, respectively then the mean values of treated broiler samples with 1%lactic acid, 1% acetic acid and1% mixture of acids increase slowly in an ascending rate at different times of storage at chilling condition till reached to 3.3×104±0.84×102, 3.4×104 ± 0.97×102, 2.3×104 ± 0.75×102 cfu/g after 12 days of chilling condition, respectively. After a treatment with 1% lactic acid ,1% acetic acid ,1% mixture of lactic and acetic acids the mean of Enterobacteriaceae count was reduced at a percentage of (92.30%, 92.30%, 89.10%), (91.02%, 91.66%, 83.97%), (90.03%, 89.74%, 77.56%), (84.61%, 84.61%, 69.87%), (73.71%, 75.64%, 62.82%), (66.02%, 69.23%, 53.84%) and (53.20%, 58.97%, 48.07%), respectively after 1, 2, 4, 6, 8,10 and 12 days of storage at a chilling condition. So, no significant difference between the mean values of Enterobacteriaceae count in treated broiler samples with 1% lactic acid, 1% acetic acid, 1% mixture of two acids.
Using of 2% lactic acid, 2% acetic acid, 2% mixture of lactic and acetic acid, the counts reduced to 0.8×103±1.62×102, 7.9×102±1.34×102, 1.1×103 ± 1.52×102 cfu/g after one day of chilling condition, respectively then the mean values of treated broiler samples with 2% lactic acid, 2% acetic acid, 2% mixture of lactic and acetic acid slowly increased in an ascending rate at different times of storage at a chilling condition till reached 7.0×103 ± 0.92×102, 5.6×103 ± 1.15×102, 5.9×103 ± 0.72×102 cfu/g after 12 days of chilling condition, respectively.
The mean values of coliforms count of untreated broiler samples 2.28×103±1.74×102 cfu/g while after treatment with 1% lactic acid, 1% acetic acid, 1% mixture of lactic and acetic acids the counts reduced to 2.9×102±1.34×102, 3.1×102±1.54×102, 2.7×102±0.24×102 cfu/g after one day of chilling condition, respectively. Then the mean values of treated broiler samples with 1% lactic acid, 1% acetic acid and 1% mixture of acids increase slowly in an ascending rate at different times of storage at chilling condition till reached to 1.3×103±1.15×102, 1.8×103±0.92×102, 8.7×102±0.84×102 cfu/g after 12 days of chilling condition, respectively. After treatment with 1% lactic acid, 1% acetic acid, 1% mixture of lactic and acetic acids the mean of coliforms count was reduced at a percentage of (87.28%, 86.40%, 88.15%), (85.08%, 84.64%, 85.52%), (82.89%, 81.14%, 83.77%), (79.82%, 76.75%, 82.01%), (75.00%, 69.73%, 79.38%), (64.91%, 63.15%, 75.86%) and (42.98%, 21.05%, 61.84%), respectively after 1, 2, 4, 6, 8,10 and 12 days of storage at chilling condition. So, no significant difference between the mean values of coliforms counts in treated broiler samples with 1% lactic acid, 1% acetic acid, 1% mixture of two acids.
The mean values of Staphylococci count of untreated examined broiler carcass samples was 1.33×103±1.57×102 while after treatment with 1% lactic acid, 1% acetic acid, 1% mixture of lactic and acetic acids the counts reduced to 1.1×102±0.61×102, 86×102±0.49×102, 0.9×102±1.41×102 cfu/g after one day of chilling condition, respectively then the mean values of treated broiler samples with 1% lactic acid, 1% acetic acid and 1% mixture of acids increase slowly in an ascending rate at different times of a storage at a chilling condition till reached to 4.3×102±0.62×102, 3.8×102±0.52×102, 4.0×102±0.75×102 Cfu/g after 12 days of chilling condition, respectively. After treatment with 1% lactic acid, 1% acetic acid, 1% mixture of lactic and acetic acids the mean of total Staphylococci count was reduced at a percentage of (91.72%, 93.53%, 93.23%), (90.22%, 91.72%, 90.22%), (87.21%, 89.47%, 88.72%), (84.21%, 84.21%, 85.71%), (79.69%, 81.20%, 81.20%), (75.93%, 78.19%, 75.18%) and ( 67.66%, 71.42%, 69.92%) respectively after 1, 2, 4, 6, 8, 10 and 12 days of storage at chilling condition. So, no significant difference between the mean values of staphylococci counts in treated broiler samples with 1% lactic acid,1% acetic acid,1% mixture of two acids.
The mean values of molds count of untreated examined broiler samples was 2.99×102±0.36×102 cfu/g while after treatment with 1% lactic acid, 1% acetic acid, 1% mixture of lactic and acetic acids the counts reduced to 1.9×102±0.25×102, 1.8×102±0.19×102, 1.7×102±0.21×102, and cfu/g after one day of chilling condition, respectively then the mean values of treated broiler samples with 1%lactic acid, 1% acetic acid and1% mixture of acids increase slowly in an ascending rate at different times of storage at chilling condition till reached 5.1×102 ± 0.17×102, 5.4×102 ± 0.16×102, 5.5×102 ± 0.65×102 cfu/g after 12 days of chilling condition, respectively. After treatment with 1% lactic acid, 1% acetic acid, 1% mixture of lactic and acetic acids the mean of total molds counts were reduced at a percentage of (36.45%, 39.79%, 43.14%), (16.38%, 26.42%, 33.11%), (6.30%, 9.70%, 16.38%), (13.71%, 10.36%, 10.36%), (30.43%, 40.46%, 53.84%), (50.50%, 57.19%, 63.87%) and (70.56%, 80.60%, 83.94%), respectively after 1, 2, 4, 6, 8, 10 and 12 days of storage at chilling condition. Statistical analysis indicated that concentrations of 2% lactic acid, 2% acetic acid and 2% mixture of lactic acid and acetic acids could reduce molds counts more than did lactic acid 1%, acetic acid 1% and mixture of lactic acid and acetic acids 1%.
The mean values of yeasts count of broiler samples was 2.95×102 ± 0.38×102 cfu/g while after treatment with 1% lactic acid, 1% acetic acid, 1% mixture of lactic and acetic acids the counts reduced to 1.1×102 ± 0.25×102, 1.6×102 ± 0.19×102, 1.3×102 ± 0.21×102, and cfu/g after one day of chilling condition, respectively then the mean values of treated broiler samples with 1%lactic acid, 1% acetic acid and1 % mixture of acids increased slowly in an ascending rate at different times of storage at chilling condition till reached 4.5×102 ± 0.17×102, 4.4×102 ± 0.16×102, 4.8×102 ± 0.65×102 Cfu/g after 12 days of chilling condition, respectively. After treatment with 1% lactic acid, 1%acetic acid, 1% mixture of lactic and acetic acids the mean of yeasts counts was reduced at a percentage of (62.71%, 45.80%, 55.93%), (52.54%, 38.90%, 35.60%), (35.60%, 22.00%, 15.20%), (5.10%, 5.10%, 8.50%), (8.47%, 28.81%, 8.47%), (25.42%, 38.98%, 49.15%) and (52.54%, 49.15%, 62.71%), respectively after 1, 2, 4, 6, 8, 10 and 12 days of storage at chilling condition.