A comparative qualitative study of the profile of volatile organic compounds associated with Salmonella contamination of packaged aged and fresh beef by HS-SPME/GC-MS.

Vacuum packaged beef strip-loins (fresh and aged) were repackaged on polystyrene trays and over-wrapped with food grade cling film for the storage study. Several volatile compounds such as 3-methyl-1-butanol, 2,3-butanedione, 2-butanone, 3-hydroxy-2-butanone, acetic acid and a few hydrocarbons were detected in the headspace of these tray packaged fresh and aged beef strip loins both in the control and Salmonella typhimurium inoculated samples, in varying concentrations. These compounds were identified using manual headspace solid-phase microextraction (HS-SPME) in combination with gas chromatography/mass spectrometry (GC-MS) over a storage period of 4 days and samples were incubated at 20°C. No naturally occurring Salmonella was present in the control samples. Hexanal (r = 0.99), carbon dioxide (r = 0.98), 3-hydroxy-2-butanone (r = 0.93) and 2-methyl propane (r = 0.95) showed positive correlations with Salmonella population for fresh beef samples. In aged beef samples, 3-methyl-1-butanol (r = 0.99), 3-hydroxy-2-butanone (r = 0.98), carbon dioxide (r = 0.98) and acetic acid (r = 0.86) showed similar trends. In fresh beef samples, F values were significant at p < 0.05 for 3-hydroxy-2-butanone and for carbon dioxide with storage time for fresh beef samples; they were significant for 3-hydroxy-2-butanone, acetic acid and carbon dioxide for aged beef samples.