Rapid electrical methods for the detection and enumeration of food spoilage yeasts

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 ammoniun 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 enumeration, as it detected more yeast species. Indirect conductance was equivalent to direct capacitance.