Instant enumeration of total viable bacterial counts for food quality assurance using ‘DEP-On-Go’ sensor

Abstract

Food quality has to be constantly monitored from farm-to-table to control foodborne illness. Total viable count (TVC), which estimates the population of live microbial load, can be an extremely useful tool for food quality assurance. This work presents the utility of an electrochemical ‘DEP-On-Go’ sensor to determine TVCs instantly and quantitatively in milk and other food samples, including vegetables, and meat, using the oxygen consumption activity of viable microbes. We present the analytical performance of our device for the sensitive detection of the TVC in packed milk with a detection limit of ≤300 CFU mL⁻¹, which fulfills the acceptable limit (<30 000 CFU mL⁻¹) recommended by Prevention of Food Adulteration (PFA) standards. We detected the TVC in raw or packed milk immediately without any pretreatment or incubation. The calibration curve of the TVC obtained by the standard plate count method and peak current resulting from the oxygen consumption activity of bacteria in milk samples showed linearity with a correlation coefficient of 0.9907 over the range of 1.8–8.7 log CFU mL⁻¹. The ‘DEP-On-Go’ sensor was further utilized to selectively determine the coliform bacteria count in milk samples with a linear coefficient of 0.9455 over the range of 0.6–7.0 log CFU mL⁻¹ within 4 hours of incubation time using selective broth media. Our results support the easy-to-detect, low cost (1–5 USD), rapid and reliable monitoring of microbial contamination using the ‘DEP-On-Go’ device, which can become a powerful mobile platform in modern food industries.