The objective of this study was to evaluate the antimicrobial and antioxidant effects of 0, 10, 20, 30 and 40% thyme and sumac hot water extract added to minced beef meat after populated with pathogenic bacteria and stored at 4±1.°C for 6 days. Total Phenolic andtotal flavonoidscompounds in thyme and sumac extracts were determined by HPLC. There antioxidant activity was screened using DPPH radical scavenging methods.Theantimicrobial activities assessment was tested by agar wells-diffusion method and minimum inhibitory concentration (MIC) using broth media.
The obtained results showed that the inhibition percentage values ranged from 35.9 to 39.6 and 25.2 to 37.6% for thyme and sumac extracts, respectively. Also, The results showed that 40% extract had the most antibacterial activity against all studied bacteria in agar wells-diffusion. Thus, this level only was further examined in broth media at levels (3 to 6%). In minced beef meat the used levels were (4, 5 and 6%) because the slight effects of the 3% concentration. Bacillus subtilis was found to be the most sensitive bacteria to sumac extract showing a MIC of 3.5%. Both S. typhimarium and E. coli were coming at the second rank with 4% while St. aureus ranked the last with MIC of 4.5%. In addition, the sumac extract inhibitor activity against all studied bacteria was better than thyme extract in broth media. In minced beef meat samples, both thyme and sumac water extracts were effect on all studied bacteria during storage period.
So that, thyme and sumac spices, which are traditionally used as astringent agents, have promising inhibitory effects against pathogenic bacteria and could be considered as natural food preservatives.