RESEARCH ARTICLE
Applicability of Micro Inoculation Culture (MIC) for Rapid Monitoring of Total Coliform Contaminants in the Food Industry

ABSTRACT

Unlike medical samples from clinics, samples associated with food products and the environment they come into contact with during their processing are characterized by low initial cell counts and large sample volumes. This calls for different strategies of handling, especially in low-resource settings and in less advanced food industrial laboratories. This paper compares three popular industrial methodologies; MPN method, Petrifilm^™ by 3M, and the standard pour plate technique, relative to a modified surface spread technique using 96-well microtiter plates (MIC). The colony enumeration results obtained from each technique showed good agreement. The miniaturized rapid protocol efficiently managed a large number of samples using multichannel autopipettes and a high-throughput design utilizing 96-well microtiter plates. Useful colony counts were obtained within 12-16 h. The analytical efficacy of the miniaturized protocol surpassed those of the three conventional methods. The colony counts from ready-to-eat product samples showed comparable results to the pour plate technique, displaying good agreement with the universally-accepted standard. The feedback by QC staff from a local Thai food factory revealed good overall acceptance of the MIC method with respect to usability, protocol design and method efficiency. The proposed miniaturized technique gave highly consistent results of colony count numbers and good colony separation. This colony enumeration consistency suggests that the miniaturized rapid protocol can economically replace the slower more complex standard protocols as an in-house protocol for food processing environment swabs.

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