Rapid quantification of coliforms in ready‐to‐eat foods using lateral‐flow immunochromatographic assay

Abstract

AbstractThe degree of coliform contamination in pastries was estimated based on culturing times until positive results were obtained with the lateral‐flow immunochromatographic assay (LFIA). Coliform genera Citrobacter, Cronobacter, Enterobacter, Klebsiella, Kluyvera, Pantoea, Raoultella, and Serratia were detected in spoiled pastries, as established with next‐generation sequencing. A lateral‐flow test strip was constructed using antibodies recognizing the above genera. The culture times required for positive detection with LFIA were 0, 3, 6, and 9 hr at initial inoculation concentrations of 3.8, 2.8, 1.8, and 0.8 log10 (cfu/ml), respectively. In pastries contaminated with >5.0, 3.0–5.0, 2.0–3.0 log10 (cfu/g) coliform bacteria, samples became LFIA‐positive from 3, 6, and 9 hr culture, respectively. LFIA showed negative for pastries with <2.0 log10 (cfu/g) coliform contamination. The quantitative category of initial coliform content before culture was predictable with 87% accuracy. This novel method can be applied to monitor food safety of other ready‐to‐eat consumables.