Rapid detection of bacteria in food using static-headspace GC×GC (Wan Sin Heng, MDCW 2023)

• 🎤 Presenter: Wan Sin Heng¹, Snehal Jadhav¹, Maiken Ueland², Robert Shellie¹´³ (¹Deakin University, Burwood, Australia. ²University of Technology Sydney, Ultimo, Australia. ³University of Tasmania, Hobart, Australia)

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15th Multidimensional Chromatography (MDC) Workshop 2024

Abstract

Microbial contamination of food is a serious threat to public health and a major hindrance to safe food production. Timely detection of pathogenic microbes is crucial for a secure food supply. Early detection of pathogenic microbes can minimise the spread of contaminated food, but current reliance on conventional culture-based methods is time-consuming and laborious. We postulated that detection of volatile organic compounds emanating from food samples (dairy milk) spiked with Escherichia coli (E. coli) might serve as putative markers to indicate E. coli presence. Our workflow employed quasi-stop-flow modulation headspace GC×GC to measure volatile organic compounds emanating from enriched milk samples spiked with E. coli and our investigation suggests that ethanol, 1-propanol, and acetaldehyde may be used as such markers.

Different incubation times (5, 10, 15, and 20 h) were investigated to determine the minimum enrichment time required to detect E. coli. Fifteen hours incubation proved adequate, with clear differentiation possible between spiked and control test solutions. Sample throughput was maximised by incorporating a back flushing step. Backflushing is readily achieved using the quasi-stop-flow column ensemble by reducing the GC inlet pressure to a value less than the second dimension (mid-point) pressure.

By using HS-GC×GC, the time-to-response can reduce by more than one-full day compared to the current conventional approaches at pre-enriched single-cell bacteria level. The developed method shows great promise to be utilised for rapid screening of microbial food contamination. Further work must investigate marker compounds for a range of bacteria in milk and other food matrices.