The essential oil extracted from the aerial parts of Thymus ciliatus harvested in the region of Tawra (North-East of Algeria) gave a yield of 2.5%. Its analysis by GC / MS has allowed the identification of twenty-four elements, mainly phenols and terpenes. The main components were: Thymol (67.78 %), p-cymene (12.25%), pseudolimonene (5.10 %), and γ-terpinène (4.42 %). Antimicrobial activity was evaluated on two pathogenic foodborne bacterial strains: Bacillus cereus and Listeria monocytogenes. These pathogens showed high sensitivity with respect to the essential oil with respective inhibition diameters of 28.6and 40mm of relatively low MICs of 0.18mg / ml. Due to these results, we may propose the use of this natural substance as a substitute for additives used in food protection.

The essential oil extracted by hydrodistillation from the aerial parts of Origanum vulgare L. harvested in the region of Skikda (North-East-Algeria) gave an excellent oil yield (2.8%). Its analysis by Gas Chromatography–Mass Spectrometry (GC/MS) identified 98.10% of its constituents. The major components are: carvacrol (47.6%), thymol (16.6%), p-cymene (13.5%) and γ-terpinene (11.2%). The aim of this study was to the preservative effect of Origanum vulgare essential oil applied to a very low concentration of 0.025% (minimum inhibitory concentration (MIC)), of a sensitive food of essential nutritional value, of great consumption and easily perishable “minced meat”, stored at different times, namely: T0 = 0 min, T1 = 40 min, T2 = 24 h, and T3 = 48 h. By studying its microbiological quality by determining the rate of reduction of the total aerobic mesophilic microflora and of Staphylococcus aureus. The addition of Origanum vulgare essential oil to minced meat allowed a highly significant reduction of 0.01<p<0.1 in total aerobic mesophilic microflora reduction rate and very highly significant (p≤0.01) for Staphylococcus aureus, and markedly increase the shelf life. This allows us to propose the use of this essential oil as a source of natural preservative substances.

In this work, the gas  chromatography-mass spectrometry (GC/MS) analysis of the essential oil of Origanum vulgare. L. obtained by hydrodistylation was warried out and it allowed to identify 98.1% of its constituents. The main components are carvacrol (47.6%), thymol (16.6%), p-cymene (13.5%) andγ-terpinene (11.2%). The chemical components of the essence are distributed over five biochemical classes represented mainly by monoterpene phenols and monoterpene carbides. The extraction gave a yield of oil 2.8%. The minimum inhibitory concentration (MIC) of this oil was determined against food spoilage bacteria and pathogenic bacteria belonging to the genus Staphylococcus tested in vitro. This study aims to enhance the value of oregano essential oil by determining its chemical composition on the one hand, and by its application as a natural antibacterial preservative in substitution of synthetic chemical additives on the other hand. The sample was incorporated into a sensitive food matrix exposed to bacterial contamination: white meat. The bacteriostatic/bactericidal power of this bioactive extract was determined by a significant reduction in the number of bacteria and a clear increase in shelf life. Thus, it is possible to propose the use of this aromatic essence as a source of natural preservative.

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