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

Essential oil monoterpenes (alpha -terpinene, (+)-limonene, alpha -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 alpha -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 mug/ml, respectively. With (+)-limonene, the mean MICs for T. candida, K. fragilis, K. thermotolerans and C. tropicalis were 39, 312, 39 and 312 mug/ml, respectively. The minimal fungal concentrations (MFCs) of the monoterpenes varied from 39 to 1250 mug/ml for the food spoilage yeasts examined. Within 60 min, alpha -terpinene (312 mug/ml) reduced the population of C. tropicalis and H. anomala from 10(5) to 10(3) cells/ml. The MIC of (+)-limonene for A. parasiticus was 78 mug/ml. As revealed by NMR, both alpha -terpinene and (+)-limonene caused membrane injury of C. tropicalis cells. Copyright (C) 2000 John Wiley & Sons, Ltd.