Expert Insight: High-Throughput Aroma Analysis of Food Products Using Direct MS

Chemical aromas are very diverse and have a wide range of sensory thresholds. Conventional analytical analyses lack the time resolution, responsiveness, and comprehensiveness of analysis required to provide rapid feedback to product developers or process-line managers. Selected ion flow tube mass spectrometry (SIFT-MS) is a revolutionary direct analysis solution to this problem.

In a recent SelectScience webinar, now available on demand, Hamish Lamotte and Yan Li of Syft Technologies present the SIFT-MS and discuss how it can be applied in the consumer goods industry, from the process line through to in vivo flavor release in the R&D lab, and how it can be adapted to meet  the analytical requirements for specific consumer goods. 

If you missed the webinar, you can now watch it anytime at your leisure. Read on for highlights from the webinar’s Q&A session.

Q: You mentioned multiple headspace extraction being possible using the autosampler. How is this done?

YL: Multiple headspace analysis enables the quantification of volatiles in solid phase from its headspace. What we do is put the solids into an autosampler headspace valve, the autosampler will flash the headspace with nitrogen and will take readings and repeat the readings continuously until we see the concentration of the volatiles decreasing to really low levels. Over a series of readings of the decay of volatiles as they are depleted from the solid phase headspace, we can quantify the total concentration by integrating the overall decay of the volatile series. Once we have that data, we can use automated analysis to give the final concentration.

Q: What other products have been tried for origin determination using SIFT-MS? 

HL: In addition to the vanilla study that we discussed, we have also done some studies on parmesan cheeses. We were looking at whether we could identify whether a parmesan cheese originated from New Zealand or from Italy. It was a fairly conclusive testing. You could tell the difference based on the aroma fingerprints. We also did another study looking at coffee beans from five different countries within the Coffee Belt to see if we could determine the origin of those beans, which also showed a good separation between the different countries of these samples. 

Q: Does the instrument require calibration before each use?

YL: Yes, it will require automated validation. But the whole process is automated with our software and takes only five minutes to complete. Unlike with traditional GC-MS calibrations, we do a single-point calibration using the Syft standard gas which has eight components in the gas with known concentrations. That's all we need to do for the daily validation and calibration of our instrument to ensure the stability and accuracy of the measurements.

Q: Is there a limit to the number of compounds that can be measured in one sample?

YL: Theoretically, there's no limit. But what needs to be kept in mind that it takes a similar time to measure each of the product lines. Although it's milliseconds, the more compounds you want to analyze, the more time it takes. The analysis will still be much faster than using traditional technology. 

Q: How was the sample for breath analysis introduced into the instrument?

HL: There are a couple of different ways that our customers can introduce breath into the flow tube of our instrument. We have a specific breath head index which is being developed for breath sampling. You can simply exhale into the breath head index and it has a chamber inside it which retains the breath sample, allowing you to get a full profile of the whole breath from the instrument. There’s also a little vent fan on the index so you can then refresh the chamber and put new breath samples in. Alternatively, some of our customers use a simple flow-pass set-up where you just have a straw to exhale through and there's no chamber where the air is held. You get a profile of the breath sample rather than an entire picture of it. Both sampling techniques give you different stages of the exhalation.  

Q: Why aren't humid samples an issue for SIFT-MS?

HL: When the instrument was originally built, we incorporated the water chemistry of any moist samples into the instrument's calculations so that it could handle it. Eventually, any moist sample will be able to be handled by the instrument because it can predict what sort of reactions will happen with increased humidity and compensate for it. All the inlets and parts of the instrument which the analyte flows through are also heated to 120 degrees to try to minimize any extra moisture from going into the instrument. Essentially, the instrument is calibrated for high-moisture content samples because we use moist air as our source of ions in the first place.

Q: Could beef quality testing or packaging testing be incorporated into a production line using SIFT-MS?

HL: The high-throughput capabilities of SIFT-MS are perfect for incorporation into production lines. We have the throughput capabilities, but we've been looking specifically at beef samples and a method to get the aroma from the beef faster to facilitate even faster throughput. We were looking at using an iKnife to increase sampling throughput. Depending on the speed of your production line, we can also increase the number of instruments for sampling.

Q: What consumables are used by the instruments?

YL: The consumables used by our instrument are simple and very low cost. We use carrier gas to carry our ions to the detector. This is normally helium or nitrogen. Other than that, we have to use a standard gas for calibration on a daily basis. A small bottle of this standard gas can last for a very, very long time. The last one is the ionized water, which we use for generating ions. These three are the major consumables. Aside from these, all you will need is to carry out maintenance on your instrument every six months.

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