Effet du pâturage à base de plantes aromatiques et médicinales sur le profil volatil de la viande de chèvre.

Abstract

North Biskra is an arid region, characterized by its richness and diversity in aromatic and medicinal plants (AMP), which are considered to be a source of bioactive natural molecules. Goats raised in this region usually graze these herbs during the day. The objectives of this thesis focus on volatile organic compounds (VOCs) characterizing the AMP and meat from goats consuming these plants. First, ethnoveterinary survey was carried to collect as much information as possible on goat farming in the Biskra area, goat meat and APM from the same study region. Secondly, the characterization of the VOCs of the most abundant plants and the most grazed one. In addition, goat meat from pasture and a concentrate diet were characterized qualitatively and quantitatively by HS-SPME analysis coupled with GC-MS. The obtained results indicate that goat meat is characterized by a specific red color, taste and odor. A total of ninety-one VOCs have been identified for APM: thirty-seven compounds for A. campestris (mainly: β-farnesene (14.17%) and β-myrcene (13.84%)), forty-two for T. polium (mainly: α-guaiene (11.33%), trans-caryophyllene (9.49%) and γ-elemene (9.25%)), thirty-five for R. officinalis (mainly: camphor (17.46%) and trans-caryophyllene (14.83 %)), fifty for J. phoenicea (mainly: α-pinene (27.18%)), fortyone for A. herba-alba (mainly: α-thujone (24.59%) and β-thujone (13.73%)) and thirty-nine for T. algeriensis (mainly: β-myrcene (13.78%) and camphor (12.29%)). As for meat, forty-four VOCs have been identified: forty-two for meat from pasture (mainly: limonene (16.94%), azulene (8.01%), 2- nonene-1-ol (7, 31%)) and twenty-two for meat from a concentrated diet (mainly: 2-nonene-1-ol (18.43%), azulene (11.01%), benzyl alcohol (9.59%) and limonene (7.91%)). A highly significant difference was noted between the two groups of meats studied for the occurrences of VOCs. Grazing goat meat had the highest levels of similarity to APM compared to goat meat from a concentrate diet. The goat meat from the pasture diet is rich in terpenes compared to the goat meat from the concentrated diet which could improve the quality of the meat and limit the oxidation of lipids and consequently, increase the stability and shelf life of the meat.