Solid phase microextraction/gas chromatography of Salmonella-infected beef

Eight strains of Salmonellae were incubated in TSB culture medium at 37 deg rees C for 24 h. Volatile compounds derived from the bacteria were collecte d using solid-phase microextraction fibers and then applied to gas chromato graphy (GC). Similarity analysis of the GC patterns thus obtained could sep arate these strains on principal component similarity (PCS) scattergrams. F ive major food-related pathogenic bacteria and 10 other bacteria (including one Salmonella strain)were also classified by growing in the same medium. It is then proposed to utilize this approach to improve the GC/PCS method o f Nakai et al. [Nakai, S.; Wang, Z. H.; Dou, J.; Nakamura, S.; Ogawa, M.; N akai, E.; Vangerstoep, J. J. Agric. Food Chem. 1999, 47, 576-583] that has been developed for screening safe foods by detecting bacteria contaminated foods. Inoculating food samples pre-enriched through preliminary incubation into a culture medium and then subjecting to the GC/PCS method after secon dary incubation enhances the detectability of pathogenic bacteria.