Inhibition of food spoilage yeasts and aflatoxigenic moulds by monoterpenes of the spiceAframomum danielli

Essential oil monoterpenes (α-terpinene, (+)-limonene, α-pinene, 1,8-cineole) of the spice Aframomum danielli were tested for in vitro antifungal activities against some food spoilage yeasts (Torulopsis candida, Candida tropicalis, Kluveromyces thermotolerans, K. fragilis, Hansenula anomala and Pichia pastoris) and mycotoxigenic moulds (Aspergillus flavus, A. parasiticus). With α-terpinene, the mean minimum inhibitory concentrations (MICs) for T. candida, K. fragilis, K. thermotolerans and C. tropicalis were found to be 4.9, 39, 78 and 156 μg/ml, respectively. With (+)-limonene, the mean MICs for T. candida, K. fragilis, K. thermotolerans and C. tropicalis were 39, 312, 39 and 312 μg/ml, respectively. The minimal fungal concentrations (MFCs) of the monoterpenes varied from 39 to 1250 μg/ml for the food spoilage yeasts examined. Within 60 min, α-terpinene (312 μg/ml) reduced the population of C. tropicalis and H. anomala from 105 to 13 cells/ml. The MIC of (+)-limonene for A. parasiticus was 78 μg/ml. As revealed by NMR, both α-terpinene and (+)-limonene caused membrane injury of C. tropicalis cells.