Induction of conductance and capacitance changes by food-borne fungi

A detailed examination was made of the conductance and capacitance changes caused by moulds and yeasts when cultured on a wide range of commercial and experimentally formulated media. Media which comprised only soya peptone and yeast extract (SP/YE) consistently elicited an increasing conductance curve of good quality. ‘Spiked’ fruit juice inocula resulted, however, in signal reversal. A comparable reversal was induced by medium supplementation with selected monosaccharides. Incorporation of a range of glucose and ammonium concentrations into SP/YE confirmed that reversal of the conductimetric responses could be induced by appropriate supplementation. Product interference may thus prove problematic. Capacitance signal responses, however, were both consistent and produced, with selected media, earlier detection times.