International Biodeterioration & Biodegradation 32 (1993) 19-32 Rapid Electrical Methods for the Detection and Enumeration of Food Spoilage Yeasts R. P. Betts Campden Food and Drink Research Association, Chipping Campden UK, GL55 6LD* ABSTRACT Methods for the electrical detection of food spoilage yeasts have been investigated; these include direct conductance, direct capacitance and indirect conductance measurement. Although these methods can be used to detect and enumerate yeasts, the two direct methods must be linked to the correct growth medium. The optimum medium for direct conductance monitoring was found to be Yeast Carbon Base and ammonium tartrate (CBAT), whereas either CBAT or Yeast Carbon Base and ammonium sulphate (CBAS) could be used for direct capacitance monitoring. CBAT could also be used in indirect conductance systems; however, in some cases a medium was not required in indirect systems, as the food sample itself provided growth requirements. Generally, a direct capacitance system was better than a direct conductance system for yeast detection and enumera- tion, as it detected more yeast species. Indirect conductance was equivalent to direct capacitance. INTRODUCTION Electrical methods have been used for many years to monitor the meta- bolism and growth of microorganisms. The detection of microbial growth using electrical systems is based on the measurement of ionic changes occurring in media, caused by the metabolism of microorganisms. The *Information emanating from this Research Association is given after the exercise of all reasonable care and skill in its compilation, preparation and issue, but is provided without liability in its application and use. 19 International Biodeterioration & Biodegradation 0964-8305/94/$07.00 © 1994 Elsevier Science Publishers Limited. Printed in Great Britain.