Ethanol production in table jelly by two species of Chrysosporium.

Abstract

Different commercial brands of tablet jelly were stored in sealed containers for 12 weeks at an initial water activity of 0.90. The surface of those containing real fruit juice became covered with a dense white mould identified as Chrysosporium inops. That of those without fruit juice did not. This type of spoilage has been observed in commercially stored samples. When spores of this fungus and the closely related species, C. xerophilum, were added to commercial tablet jelly, the fungi grew only on samples containing real fruit juice. It is suggested that the fruit juice may provide some essential nutrient required for growth of these nutritionally fastidious species as well as the fungal spores themselves. Ethanol was detected in the headspace gas of stored samples of mouldy jelly. The production of ethanol by the two Chrysosporium species was confirmed by fermentation of glucose in liquid batch culture: approximately 2% ethanol was formed in 14 d. The ability of C. xerophilum and C. inops to utilize the Embden-Meyerhof-Parnas pathway may explain why these slow-growing xerophilic moulds become dominant after storage at low oxygen tension.