Abstract

This study was designed to evaluate antimicrobial and antioxidant effect of ethanolic and aqueous extracts and essential oils of red onion, garlic and leek against Escherichia coli O₁₅₇:H₇, Staphylococcus aureus, A.F., 4, Salmonella typhimurium, A.F., 3, Aspergillus niger, H.U.B., 1, Aspergillus ochrecies, H.U.B.,12 and Fusarium oxysporum, H.U.B., 3 in sausage. The susceptibility of these isolates toward the extracts of these plants was compared with some antibiotics (oxytetracycline, tetracycline, ampicillin and amoxicillin) used as positive control. The phenolic contents and stable free radical 2,2-diphenyl-1-picrylhydrazyl was determined. Results show that the concentration, 60 mg/ml of ethanolic extracts and essential oils represented the optimum concentration against all microorganisms. The essential oils exhibited higher effect than ethanolic and aqueous extracts against all tested microorganisms, especially at 60 mg/ml concentration of leek essential oils, whereas red onion, garlic and leek essential oils showed a stronger antimicrobial activity for decreasing count of E. coli O₁₅₇:H₇, S. aureus, A.F., 4 and Salmonella typhimurium, A.F., 3 in sausage. The phenolic contents and antioxidant activity were higher in essential oils of garlic, leek and red onion whereas the lower contents and activity were shown in aqueous extracts. The essential oils of red onion had the highest phenolic contents and antioxidant activity in contrast to garlic essential oils.

Key words:  Microorganisms, antioxidant, essential oils, ethanolic, aqueous extracts, onion, garlic, leek.