Abstract
There is a growing interest concerning alternative antioxidant active compounds, including plant extracts and essential oils that possess multifunctional properties that facilitate their classical role as natural food additives with antibacterial, antifungal and anti-inflammatory activities. The aim of the study was to evaluate the effects of the water extract of three plants Ginger, Thyme and Marjoram for their phenols, flavonoid contents, antioxidant ability and antimicrobial potentials. The obtained results revealed that total phenolics and total flavonoids content of herbal infusions of ginger, thyme and marjoram was 67±2.86, 126.87± 0.93 and 139.76±2.60 mg galic acid equivalents (GAE) /g respectively, while mixture extract (ME) of them gave 256.46±2.91. Also, ME gained the highest content of total flavonoid (190.83± 4.27) mg catechol/g, while ginger, thyme and marjoram gave 37±1.39, 106.14±0.47 and 100.27±3.23 mg/g, respectively. Results of antioxidant activity represented in IC50 (inhibition concentration) showed that the best extract was (ME) with value of 4.25 μg/ml compared with ascorbic acid in value 4.08 μg/ml follow them marjoram, thyme and ginger by 10.1, 18.3 and 231.38, respectively. The antimicrobial activity of (ME) exhibited the maximum inhibitory zone diameter (IZD) against most food poisoning bacteria as Staph .aureus, Bacillus subtilis, Clostridium botulinum, Salmonella and E.coli at different concentrations. Depending on up mentioned results; ME was selected for application in beef burger as natural preservative. pH values of beef burger samples after 21 days of cold storage were 6.14±0.76, 5.97±0.96, 6.11±0.85, 5.98±0.64, 5.95±0.65, 5.92±0.34 for Control, BHT, (ME) 0.02%, (ME) 0.1%. (ME) 0.2% and (ME) 0.5%, respectively. Besides, all tested groups showed significant decrease in water holding capacity (WHC %) from day 0 to day 21 of storage at which the lowest value was for control group (92.38±0.12) and the highest was for (ME) 0.5% (95.38±0.75). From the upraised results, It could be concluded that there was a strong synergistic effect between the extracted based on ME was able to retard lipid, protein oxidation and inhibit the microbial growth during cold storage of beef burger.

Key words: Ginger, Thyme, Marjoram, Antioxidant, Antimicrobial, Meat Products