A rapid detection method for microbial spoilage of agro-products based on catalase activity

Microbial spoilage of agro-products should be monitored for the quality and safety of food. In this study, we successfully developed a catalase detection device employing an oxygen sensor to monitor the microbial spoilage of milk and stored grain samples. The results showed that catalase activities correlated well (>0.99) with the microbial counts of four pure fungi and aerobic bacteria that commonly cause spoilage of stored grains and milk, respectively. The correlation coefficient between catalase activity and microbial counts reached 0.99 in stored grain samples and 0.96 in milk samples, and the changes in the microbial counts could be effectively monitored by detection of catalase activities during the microbial spoilage of stored wheat and milk. The detection of catalase activity could be accomplished in 10 min to reveal mold counts in agro-products, and it showed higher sensitivity than the conventional agar plate method. Therefore, the proposed catalase activity-based method could be rapidly and sensitively applied to the detection of microbial spoilage of agro-products.