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 antif ungal activities against some food spoilage yeasts (Torulopsis candida, Can dida tropicalis, Kluveromyces thermotolerans, K. fragilis, Hansenula anomal a and Pichia pastoris) and mycotoxigenic moulds (Aspergillus flavus, A. par asiticus). With alpha -terpinene, the mean minimum inhibitory concentration s (MICs) for T. candida, K. fragilis, K. thermotolerans and C. tropicalis w ere 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. tropi calis were 39, 312, 39 and 312 mug/ml, respectively. The minimal fungal con centrations (MFCs) of the monoterpenes varied from 39 to 1250 mug/ml for th e food spoilage yeasts examined. Within 60 min, alpha -terpinene (312 mug/m l) 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 r evealed by NMR, both alpha -terpinene and (+)-limonene caused membrane inju ry of C. tropicalis cells. Copyright (C) 2000 John Wiley & Sons, Ltd.