New SBSE Twisters Detect Hard-to-analyze Flavors

In beverage production, getting the right flavor is crucial. Often, certain solutes can significantly affect the tastes of a number of beverages ranging from water and tea to beer, wine, whiskey and coffee. Identifying the analytes that can affect flavor can be done by gas or liquid chromatography, but any successful analysis depends on the effectiveness of the initial sample extraction.

GERSTEL’s line of stir bar sorptive extraction (SBSE) devices, manufactured under the Twister name, is useful in analyzing aromas and other taste influences because of the stir bar’s versatile polydimethyl siloxane (PDMS) coating. The newest generation Twisters, coated with polyethylene glycol-modified silicone (EG), provide enhanced extraction of polar (hydrophilic) chemicals.

Two new Twister extraction modes are now available: multi-SBSE, which consists of one PDMS Twister at the bottom of the vial and an EG Silicone Twister suspended on the vial’s inner wall, and derivat-SBSE, which is SBSE conducted with in-situ derivatization (such as acylation, esterification or oximation).

Investigators tested these applications of Twister technology to determine the benefits they provide for general aroma/off-flavor analysis in green tea, and for two targeted analyses in beer.

What they found is that the new Twister solutions provide more uniform enrichment of aroma compounds than conventional SBSE, and provides higher selectivity in GC-MS analysis.

For the green tea analysis, multi-SBSE with the PDMS and EG Silicone Twisters detected a number of solutes that contribute to the aroma of roasted green tea, using just 5 ml of sample. Compounds detected in the chromatogram included coumarin, guaiacol, p-cresol, indole, 2-ethyl-3, 5-dimethyl pyrazine, linalool, geraniol, and cis-jasmone.

For the first beer analysis, derivat-SBSE was used to detect the aldehyde E-2 Nonenal, a major source of stale flavor in beer even at very low concentrations. The challenge for analyzing E-2 Nonenal has been the high levels of matrix components that interfere with its detection. Derivat-SBSE (derivatization with pentafluobenzylhydroxylamine followed by Twister extraction) decreased the matrix interference and allowed highly sensitive gas chromatography (GC) and mass spectrometry (MS) detection.

The second beer analysis focused on tropical aroma thiols, such as 3-mercaptohexan-1-ol or 3-mercaptohexyl acetate, which create fruity, citrus or tropical aromas in beer at very low odor threshold levels. Here, derivat-SBSE using a PDMS Twister and propiolic acid as a derivatization reagent extracted cis-3 mercaptohexyl acetate. Gas chromatography purification and mass spectrometry detected the thiol below its odor threshold of 5.0ng/L.

The studies show that GERSTEL Twister technology — in particular the new multi-SBSE and derivat-SBSE modes — can be used for non-targeted analysis of many aroma compounds, and targeted analysis of off-flavors and key aroma compounds. These extractions are solvent-less and allow quantitative analysis with very low detection limits.

Learn more about using Twisters to enhance your analyte extraction and analysis in our article in GERSTEL Solutions Worldwide titled, “The Twister Sisters Pick Up the Flavors.”

After reading the details, feel free to reach out to us for a deeper conversation about tactics for sample preparation in your own aroma analyte and beverage analysis studies.