Antimicrobial activity of olive leaves extracts and application of leaves powder in meat preservation

Abstract

: The applications of natural antimicrobial compounds from plants in food becomes very frequent. Olive leaves extracts were assessed as antimicrobial agents. Petroleum ether, ethyl acetate, methanol, and ethanol 50% were used for extraction of phytochemicals and disk diffusion method was applied against tested bacterial strains. Ethanol 50% revealed the greater extraction yield 22.5% followed by methanol 8.2%. Ethyl acetate, methanol, and ethanol 50% extracts showed good antibacterial activity against Gram-positive strains at concentration 10 mg/disk whereas Listeria monocytogenes was the most susceptible strain followed by Staphylococcusaureus. In agreement with the current trend of raising the value to natural resources, the direct addition of natural compounds to food is the most common method of application. Olive leaves powder was added to minced meat as a preservative at concentrations of crude extract percent of ethanol 50% equivalent to dried olive leaves powder: 16 and 32 mg crude extract per gram of meat. Results indicated that minced meat treated with olive leaves powder showed a decrease in total viable count as well as total coliform count in comparison with control along storage period at 4 : 6°C. Staphylococcus aureus and Escherichiacoli were killed by the effect of olive leaves powder addition in meat samples. Organoleptic evaluation showed that olive leaves powder at concentration 16 mg/g enhanced the taste of minced meat with no significant differences in comparison with control sample in other sensory attributes.