13,700
edits
Changes
no edit summary
In 2007, the Australian team of Grbin et al. developed a complex and unique method of analyzing forms of THP using a Finnigan TSQ 70 mass spectrometer directly coupled to a Varian 3400 gas chromatograph. The chromatograph was equipped with a 30 m J&W Carbowax 20 CAM fused silica column, 0.25 mm i.d, and 0.25 μm film thickness. They were able to confirm that higher lysine levels increased the amount of ATHP produced (but not ETHP), although with diminishing increases of THP as the lysine level was increased. They also discovered that L-ornithine also functioned as a precursor for THP production in ''Brettanomyces''. The group proposed a biochemical pathway for the different forms of THP in ''Brettanomyces'' <ref name="Grbin_2007" />. More recently, Hayasaka (2018) developed a reliable and rapid but pricey method to detect THP in wine using specialized HPLC-APCI-MS/MS equipment <ref>[https://www.sciencedirect.com/science/article/pii/S0021967318315668?via%3Dihub Quantitative analysis of mousy off-flavour compound 2-acetyl tetrahydropyridine in wine using liquid chromatography tandem mass spectrometry interfaced with atmospheric chemical ionisation. Y.Hayasaka. 2018. DOI: https://doi.org/10.1016/j.chroma.2018.12.047.]</ref>.
==Detection Methods==Due to the specialized GC/MS equipment needed for measuring forms of THP that most labs do not have, certain answers will be difficult to obtain. Some studies have used alkaline strips as a way to smell the aroma of THP, and while not as precise as the specialized GC/MS lab equipment, could still help further the understanding of THP. These strips were prepared in the following way: knowing that mousy off-flavour has a lingering sensory impact, the technique of alkaline paper strip assessment was adapted from Heresztyn (1986a). Paper strips (Whatman No. 1, 4–5 mm × 50 mm) were prepared by soaking in NaOH (0.1M) and drying overnight at room temperature. The alkaline paper strips were then briefly dipped into cell-free samples (centrifuged) and immediately assessed for the mouse-like odour by sniffing <ref>Private correspondence with Dr. Paul Grbin by Dan Pixley. 11/2/2017.</ref>.
Other techniques for detected THP in food have been developed, which might be applicable to wine or beer. For example, Grimm et al. (2001) developed a a technique for detecting 2-acetyl pyrroline (APY or 2AP) in rice. The rice samples had to be heated to 80-85°C in order to extract the volatile APY, and then APY levels in the headspace of the rice container could be detected using solid phase microextraction (SPME) with fibers that operate at the higher temperatures <ref>[https://www.ncbi.nlm.nih.gov/pubmed/11170584 Screening for 2-acetyl-1-pyrroline in the headspace of rice using SPME/GC-MS. Grimm CC, Bergman C, Delgado JT, Bryant R. 2001.]</ref>. It isn't known if such methods would also work for measuring THP compounds in beer or wine, but they could provide a potential option for beer and wine researchers.