Automated technique for isolation of volatile food compounds

Researchers from the Leibniz Institute for Food Systems Biology at the Technical University of Munich (LSB) have automated an established method for the gentle, artefact-avoiding isolation of volatile food ingredients. As the team’s comparative study shows, automated solvent-assisted flavour evaporation (aSAFE) offers significant advantages over the manual process, achieving higher yields on average and reducing the risk of contamination by non-volatile substances.

The optimised method is particularly important for odorant analysis. Odorants contribute significantly to the sensory profile of food and have a major influence on eating pleasure. Knowing the key odorants that shape the aroma of a food is therefore of interest both for analytical quality control and for targeted product development in the food industry.

Isolating volatile compounds from food is not trivial. Many established methods lead to losses of labile odorants as well as to odour-active artefacts and are therefore unsuitable for odorant research. The manual SAFE technique developed in 1999 made it possible for the first time to easily isolate even thermally labile odorants from food without artefact formation.

“This is an important prerequisite for using further analytical methods to identify the key odorants,” said doctoral student Philipp Schlumpberger, who contributed to the study.

Today, manual SAFE is established worldwide as a standard procedure in aroma research. Nevertheless, the research team saw a need for optimisation in terms of ease of use, yields achieved and reducing the risk of transferring non-volatile material, which can significantly interfere with subsequent analytical steps.

“As we discovered, the problems are mainly associated with the manual operation of the valve on the dropping funnel,” said Martin Steinhaus, section and working group leader at LSB. “Therefore, we replaced it with an electronically controlled pneumatic valve. To fully automate the SAFE apparatus, we optionally extended it with an automatic liquid nitrogen refill system as well as an endpoint detection and shutdown system.”

The team’s study, published in the journal European Food Research and Technology, shows that the installation of the automatic valve increased yields, particularly for lipid-rich food extracts and for odorants with comparatively high boiling points. In addition, operator errors, which can lead to contamination of isolates with non-volatile substances in the manual version, are eliminated with the automated SAFE.

“Automated SAFE has replaced the manual variant in our laboratories,” said principal investigator Martin Steinhaus. “Other academic and industrial research groups are already following our example.”

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