Antimicrobial activity of extracts from Cymbopogon citratus L. and of Mentha spicata L. against fungal and bacterial strains isolated from peuhl’s cheese (Waragashi) produced in Benin

The present research aims to evaluate the antimicrobial potential of extracts from Cymbopogon citratus L. and Mentha spicata L. against the fungal and bacterial strains that cause peuhl’s cheese (Waragashi) deterioration. The essential oils have been extracted by hydrodistillation with Clevenger-type apparatus and analyzed by gas chromatography and gas chromatography coupled with mass spectrometry. The non-volatile compounds have been extracted by maceration of the powder from leaves of each studied plants in aqueous solvents, ethanolic and hydroethanolic solvents. The antimicrobial properties of the extracts have been evaluated by the agar diffusion method against the strains isolated from cheese. The yields of extraction of essential oils were 1, 11% for Cymbopogon citratus and 0, 27% for Mentha spicata. The hydroethanolic extraction has most high yield for the two plants (18, 32 % and 15, 06% for Cymbopogon citratus and Mentha spicata respectively). The non-volatile extracts revealed the presence of catechic tannins, polyphenols and flavonoïdes in the two plants. The results from the microbiological characterization of the cheese samples reveal that they were all contaminated by mildews, yeasts, staphylococci, coliformes and Escherichia coli. The identification of the fungal flora of cheeses revealed presence of the Penicillium spp. During the tests, the volatile extracts were more active on the identified strains than their non volatile equivalents.