An oxygen electrode-based assay of catalase activity as a rapid method for estimating the bacterial content of foods

An oxygen electrode-based assay of catalase was developed as a simple method of assessing contamination by bacteria capable of respiration. The method gave a rapid and reasonable quantification of cell numbers in pure cultures and was able to detect 10³ bacteria/ml in some cases. The sensitivity of the method was dependent on the identity of the culture and when applied to foods the sensitivity was reduced due to the presence of non-microbial catalase. The use of electropositively charged filters to remove the organisms from the food sample improved the sensitivity and the relationship between catalase activity and cell numbers in some foods.