22 research outputs found
Detection of Listeria monocytogenes in cut melon fruit using analysis of volatile organic compounds
Ready-to-eat fresh cut fruits and vegetables are increasingly popular, however due to their minimal
processing there is a risk of contamination with human pathogens. Listeria monocytogenes is of particular
concern as it can multiply even at the low temperatures used to store fresh cut products pre-sale. Current
detection methods rely on culturing, which is time consuming and does not provide results in the time
frame required. Growth of bacteria on a substrate alters its chemical composition affecting the profile of
volatile organic compounds (VOCs) emitted. Use of VOCs as a detection method has been hampered by
lack of sensitivity and robust sample collection methods. Here we use thermal desorption gas chromatography
time of flight mass spectrometry (TD-GC-TOF-MS) followed by analysis with PerMANOVA to
analyse VOC profiles. We can discriminate between fresh cut melon cubes inoculated with 6 log CFU/g of
L. monocytogenes and uninoculated controls, as well as melon cubes inoculated with <1 log CFU/g of
L. monocytogenes stored for 7 days at 4 C and following equilibration for 6 h at 37 C. This is a substantial
advance in sensitivity compared to previous studies and additionally the collection method used allows
remote sampling and transport of the VOCs, greatly facilitating analyses