Transcript Slide 1
Detection of VOC’s in Spoiling Pork using Field Asymmetric Ion Mobility Spectroscopy Meat Transportation Method The spoilage of meat during storage and transportation, due to the growth of bacteria populations, is a problem with obvious consequences, such as a loss of profits to a meat company due to subsequent recalls of product, not to mention the possibility of food borne illness, and loss of consumer confidence. 8 Million trucks a day are used to transport meat across the US and prevention of meat spoilage is achieved through appropriate temperature control. However there are reported instances (on a daily basis) where the meat has arrived at the destination spoiled, even though passing the incoming core and surface temperature checks. The cause of this can be attributed to mechanical or deliberate failure of the refrigeration unit, exposing the meat to elevated temperatures, which increases the bacteria's growth rate for the period of time that the refrigeration unit is turned off or being repaired. This type of failure cannot be detected with current incoming inspection procedures and unfortunately the methods for determining the presence of bacteria can take several days to give result. Therefore a rapid method of detection of bacteria is needed. With this in mind the feasibility of using the Lonestar system for the detection of the bacteria metabolites within the headspace of a meat sample was investigated. A Lonestar unit was used to monitor the out-gassed volatiles of pork samples incubated at 25C every hour over a 24 hour period. A control sample was kept refrigerated over the period and used as a reference. For each hour adsorbent trap samples were taken and analyzed via thermal desorption gas chromatography (TD-GC-MS) for volatile identification, along side bacterial swabs so that bacterial APC counts could be determined through traditional growth methods. The Lonestar Spectra in Figure 2 clearly shows peak height increases as the bacterial count increases over time. The excel plot in Figure 3 shows how the peak of pork at 25C increases over the 24 hour period while the refrigerated pork does not increase. Results Acetic anhydride methoxy 2propanol 1 Methanecarbothiolic acid Tetramer Acetaldehyde Lonestar: Field Asymmetric Ion Mobility Spectrometer Lonestar (Figure 1 below) is a powerful and adaptable chemical monitor in a portable, self contained unit. Incorporating Owlstone’s proprietary FAIMS technology, the instrument offers the flexibility to provide both rapid alerts and detailed sample analysis. It can be trained to respond to a broad range of chemical scenarios and can be easily integrated with other sensors and third party systems to provide a complete monitoring solution. As a result, Lonestar is suitable for a broad variety of applications ranging from online/at line process monitoring to lab based R&D. Sulfurous acid T0 – Log 2.75 3 methylbutanal T4 – Log 2.96 Figure 4 Chromatogram of pork headspace at T4 Subsequently, volatile organic compounds were identified via TD GC-MS and the resultant chromatogram is shown in Figure 4, along with the primary chemical compounds identified. Taking in to consideration the negative mode response, it is thought that the Lonestar was responding to the sulphur containing metabolites released from the bacteria that was growing on the pork. Namely sulphurous acid and the methanecarothiolic acid. Conclusion Figure 1 Lonestar T8 – Log 4.32 Figure 2 Lonestar Spectra T24 – APC not done The Lonestar FAIMS unit detected pork with a bacterial log 2.96, well before the meat is considered spoiled. Therefore providing proof of principle for early detection of bacterial APC count. The method of detection is both simple to use (dock personnel) and gives a response in under a 2 minutes, which will allow meat companies to perform quality control measurements for the presence of bacteria in delivered meat (2000 lb. combos) quickly and reliably.