Fennel (Foeniculum vulgare) essential oil and supercritical fluid extracts as novel antioxidants and antimicrobial agents in beef burger processing

Fennel (Foeniculum vulgare) essential oil (EO) and its supercritical fluid extracts (SFE1 and SFE2), as well transanethole as a standard compound, were added in basic formulation of beef burgers, at two levels (0.075 and 0.150 mu L/g). The main goal of this study was to evaluate the antioxidative and antimicrobial effects of fennel extracts (EO and SFEs) in beef burgers during three days of refrigerated storage. The preservative potential for controlling L. monocytogenes and E. coli growth in these meat products was also assessed. Both types of fennel extracts (EO and SFEs) significantly (P < 0.05) reduced lipid and protein oxidation and microbiological growth (aerobic mesophilic bacteria, lactic acid bacteria, and Enterobacteriaceae) in beef burgers. Results indicated that SFE1 and SFE2 had a higher antioxidative potential than EO and trans-anethole. Higher concentration (0.150 mu L/ g) of fennel extracts (EO and SFEs) and trans-anethole efficiently inhibited the growth of L. monocytogenes. Therefore, the results of this study displayed significant antioxidative and antimicrobial potential of fennel EO and, especially, SFEs as novel natural ingredients in beef burger processing.