Detection of Listeria monocytogenes in cut melon fruit using analysis of volatile organic compounds. (April 2016)

• Record Type: Journal Article
• Authors: Spadafora, Natasha D.; Paramithiotis, Spiros; Drosinos, Eleftherios H.; Cammarisano, Laura; Rogers, Hilary J.; Müller, Carsten T.
• Is Part Of: Food microbiology. Volume 54(2016:Apr.)
• Page Start: 52
• Page End: 59
• Publication Date: 2016-04
• Subjects: Detection method -- Listeria monocytogenes -- GC–MS -- Ready-to eat fruit salad -- Postharvest storage -- Volatile organic compounds; Food Microbiology -- Periodicals; Aliments -- Microbiologie -- Périodiques; Food -- Microbiology; Periodicals; Food -- Microbiology -- Periodicals; Food contamination -- Periodicals; 664.001579
• DOI: 10.1016/j.fm.2015.10.017
• Languages: English
• ISSNs: 0740-0020

Abstract

Abstract: 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. Highlights: VOCs were used to detect Listeria monocytogenes inoculated onto fresh cut melon cubes. Detection was optimal after incubation of the melon cubes for 6 h at 37 °C. Detection of inoculation levels as low as <1 log CFU/g of melon was achieved. Thermal desorption gas chromatography time of flight mass spectrometry was used. Whole profiles of volatile organic compounds were recorded and analysed.