BACKGROUND AND OBJECTIVE: Synthetic additives are used in food industry to prevent contamination of food and reduction of microbial growth, while special attention have been paid to the use of natural anti-bacterial products because of higher food safety. Since plants are potential sources of anti-infective agents, the present study was conducted to study the antioxidant and antimicrobial effects of ethanolic extract of fennel (Foeniculum vulgare Mill) seeds.

METHODS: In this experimental study, the ethanolic extract was prepared after obtaining the fennel seeds. To analyze the antimicrobial effect of the extract, the Micro dilution method was used based on 9 concentrations of 100, 50, 25, 12.5, 6.25, 3.12, 1.56, 0.78 and 0.39% on food isolates (kept in microbial bank) and standard strains of Escherichia coli 1270 PTCC, Salmonella enterica 1709PTCC, Bacillus cereus 11778ATCC and Staphylococcus aureus 1112PTCC. To change the antioxidant effect of the ethanolic extract of fennel, 2,2-diphenyl-1-picrylhydrazyl (DPPH) method was used in 7 concentrations of 1000, 500, 400, 300, 200, 100 and 50 ppm.

FINDINGS: Salmonella enterica food isolates showed highest level of resistance (2.3 of isolates grew at concentrations above 12.5%) while Staphylococcus aureus isolates showed highest level of sensitivity (without growth at concentrations above 12.5%) against ethanolic extract of fennel (p>0.05). In all the examined concentrations, the antioxidant effect of the ethanolic extract of fennel seed was reported to be less than synthetic antioxidants BHA (Bytalyted Hydroxy Toluene) (p<0.05).

CONCLUSION: According to the results of this study, the ethanolic extract of fennel seed benefits from appropriate antibacterial and antioxidant properties and thus can be used in combination with other preservatives to preserve food against various oxidative systems and microorganisms that cause infection and intoxication.