Evaluation of Cinnamomum verum Essential Oils against Ochratoxin A-producing Aspergillus parasiticus in Stored Wheat, Maize and Rice

Eight essential oils: Zingiber officinale, Curcuma longa, Eucalyptus globulus, Syzygium aromaticum, Nigella sativa, Elettaria cardamomum, Cinnamomum verum and Cuminum cyminum were evaluated for antifungal activity against Ochratoxin A (OTA)-producing Aspergillus parasiticus (n = 3) using grains as a substrate. Minimum inhibitory concentration (MIC) and log reduction assay were used to evaluate the antifungal activity. Both the highest zone of inhibition (24.00 +/- 2.00 mm) and least minimum inhibitory concentration (1.04 +/- 0.45 mu g/mL) were recorded for C. verum essential oils. By log reduction assay S. aromaticum, C. verum and E. globulus essential oils exhibited antifungal activity after 15 min of exposure. After 30, 60 and 90 min of exposure of A. parasiticus spores to selected essential oils, complete inactivation of fungal spores (6 +/- 0.00 log reduction) was observed. In stored grains, inoculated with A. parasiticus, the lowest OTA (8.16 +/- 0.05 ng/g) was observed at 10% moisture in broken rice. An increase in OTA production was noticed with an increase in moisture from 10-40% but this trend reversed at 50-70% moisture. No increase in OTA in un-inoculated and C. verum essential oil-treated inoculated grains was noticed. Gas chromatography-mass spectrometry (GC-MS) analysis indicated the highest percentage of oleic acid (23.7%) in C. verum. Cinnamomum verum (cinnamon) oil is an effective and safe antifungal agent against A. parasiticus in stored grains.