Effect of Combined Cinnamon and Clove Oil Against Major Moulds Identified from Rubberwood (Hevea brasiliensis)

Antimicrobial activities of pure and combined cinnamon and clove oils in a ratio of 1:1, 1:3, 1:5, 1:7, 3:1, 5:1 and 7:1 against major mould found on rubberwood (Aspergillus niger WU001, Penicillium chrysogenum WU002, Penicillium sp. WU003) were investigated using a broth dilution method at a concentration of 10 - 100 μL/mL. The higher ratios of cinnamon and clove oils (3:1, 5:1 and 7:1) were stronger inhibitors than the lower ratios of cinnamon and clove oils (1:1, 1:3, 1:5 and 1:7) and the pure cinnamon or clove oil. The minimum inhibitory concentration (MIC) of the combined cinnamon and clove oils at the ratio 5:1 was determined to be 50 μL/mL for all moulds. Antifungal activity of the combined cinnamon and clove oils (5:1) at a concentration of 50 μL/mL was further examined on rubberwood specimens under storage conditions of 30 °C and 100 %RH. It was found that all moulds on rubberwood specimens were completely inhibited for at least 12 weeks under the storage conditions examined.