Food preservative potential of essential oils and fractions from Cymbopogoncitratus, Ocimum gratissimum and Thymus vulgaris against mycotoxigenic fungi
J. Nguefack, J.B. Lekagne Dongmo, C.D. Dakole, V. Leth, H.F. Vismer, J. Torp, E.F.N. Guemdjom, M. Mbeffo, O. Tamgue, D. Fotio, P.H. Amvam Zollo and A.E. Nkengfack
International Journal of Food Microbiology, Volume 131, Issues 2-3, 31 May 2009, Pages 151-156
2009
บทคัดย่อ
The food preservative potential of essential oils from three aromatic plants Cymbopogoncitratus, Ocimum gratissimum and Thymus vulgaris and their fractions was investigated against two mycotoxigenic strains each of Aspergillusochraceus, Penicilliumexpansum and P. verrucosum. The fungicidal activity was determined and expressed as a Number of Decimal Reduction of the colony forming units per ml (NDR cfu). The influence of pH variation on this activity was studied. The NDR cfu varied with the essential oils and its concentration, the pH of the medium and the strain tested. The essential oils from O. gratissimum exhibited the highest activity against the six fungal strains under the three pH tested. T. vulgaris and C. citratus essential oils were less active against the Penicillium species tested and A. ochraceus, respectively. Potassium sorbate did not present any activity at pH 6 and 9. At pH 3, its NDR cfu was the lowest against the six fungal strains. At the same pH and at 4000 ppm, the three essential oils presented a NRD cfu ≥6 against strains of A. ochraceus and P. expansum. The same result was obtained with T. vulgaris and C. citratus at 8000 ppm against both strains of P. verrucosum. The highest activity of the three essential oils was recorded at pH 3 against A. ochraceus strains and at pH 9 against both species of Penicillium. From the fractionation, three active fractions were obtained each from C. citratus and O. gratissimum, and two active fractions from T. vulgaris. These active fractions exhibited a NDR cfu, two to seven folds higher than that of the complete essential oils.