الفهرس 
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Abstract
The present study was designed to investigate antimicrobial and antioxidant activity of green tea and rosemary extracts by added this extracts on minced meat samples. About 5 kg minced meat samples were collected from different butchers shops from Tanta city and transported in an ice box as rapidly as possible to the laboratory. Minced meat divided into 2 groups, untreated (control) and treated samples. The treated samples homogenized with green tea extract (700 ppm) , green tea extract (1000 ppm), rosemary extract (0.2%), mixture of green tea extract (500 ppm) & rosemary extract (0.2%),and mixture of green tea extract (500 ppm) & rosemary extract (0.3%). The minced meat samples were examined physically, bacteriologically and chemically to determine their keeping quality by counting aerobic plate, Staphylococcal and Enterobacteriacae counts, as well as measuring pH, TBA and TVN immediately after preparation (“0”) to 6 days of chill storage (4±1°C). The results showed that sensory analyses of control (untreated groups) remain accepted until 3 rd day while treated groups with green tea extract (700 ppm) and rosemary extract (0.2%) remain accepted until 4th day. Moreover, the present data mixture of green tea extract (500 ppm) & rosemary extract (0.2%), and mixture of green tea extract (500 ppm) & rosemary extract (0.3%) remain accepted until 5th day as well as treated groups with green tea (1000 ppm) extract still accepted until 6th day.
Also, untreated samples showed the highest APC and Enterobacteriaceae counts (log. cfu/g) comparing to the treated ones. Both of APC and Enterobacteriaceae counts were gradually increased during cold storage for all samples with different ratios depending on the type and concentration of the extracts. The treated samples with green tea (1000 & 700 ppm) showed the lowest counts followed by mixture of green tea (500 ppm) & rosemary extract (0.3%) at all days of cold storage.
As well as showed results of Staphylococcus count (log. cfu/g) of treated and untreated minced meat groups show significant differences during cold storage(4±1°C). The treated groups with rosemary extract (0.2%) (3.81±0.006) (log. cfu/g) were the lower while untreated groups were the highest at zero day (4.57±0.02) cfu/g. Also at 4th day rosemary extract (0.2%) followed by mixture of green tea extract (500 ppm) & rosemary extract (0.3%) and mixture of green tea extract (500 ppm) & rosemary extract (0.2%) (5.05±0.05, 5.10±0.17, 5.12±0.13) (log. cfu/g) were the lowest, while those treated with green tea extract (700 ppm) and green tea extract (1000 ppm) at 4th day (5.77±0.007, 5.59±0.11) (log.cfu/g) were the highest, respectively.
Also, Staph. aureus count (log. cfu/g) showed greatly inhibition by treated groups as in 2nd day of storage control was 4.6 log. cfu/g while the treated groups showed 100% reduction of Staph. aureus count.
Moreover, the results showed the reduction percentage of APC , Staphylococci and Enterobacteriaceae counts. The highest reduction percentage were in green tea extract (1000 ppm) which recorded 97%, 80%, 59% at the days of cold storage.
It is evident from the present investigation that the differences in pH mean value between different treated and untreated samples were significant (P<0.05) during storage at (4±1°C) . The results showed an increase in pH mean values in untreated groups and decrease in treated ones. The highest rates were found in control samples (6.0±0.14) while, treated samples with green tea (700 ppm) were the lowest (5.8±0.1) followed by mixture of green tea extract (500 ppm) & rosemary extract (0.2%) (5.9±0.2), green tea (1000 ppm), rosemary (0.2%), mixture of green tea extract (500 ppm) & rosemary extract (0.3%) at 4th day of cold storage at (4±1°C), respectively.