Abstract
Rapid and sensitive measurement systems for pathogenic bacteria have been required for food safety assessment. In this study, we performed the quantitative detection of bacteria contained in beverages with combination of dielectrophoretic (DEP) condensation and fluorescence image analysis, and verified the quantitative validity of the present measurement system. The detection error against the collection number of S. cerevisiae was within 15% under the present conditions, and the detection accuracy is comparable with other conventional methods. Different variations of trapping numbers of bacteria for driving frequency and bacterial concentration were observed in green tea and mineral water in spite of same conductivity. It is because the components of green tea influenced DEP parameters. The flow characteristics of bacterial trapping number in the upper and lower regions of electrodes provided the quantitative evaluation of trapped bacteria on the whole electrodes. Our method has advantages in terms of rapid response and easy operation using DEP and is possible for the detection and visualization of each cell with fluorescence stain. Therefore, it can be applied to further specific samples of low concentration or localized trapping compared with other DEP measurements.
