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Tetrahydropyridine

12 bytes added, 16:25, 23 April 2019
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In 2007, 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 <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>.
Due to the specialized GC/MS equipment needed for measuring forms of THP that most labs do not have, other human sensory-based methods have been developed in the winemaking world. Originally, a "palm & sniff" method was developed to detect THP where a small amount of wine is rubbed on the palm which increases the pH of the wine and then immediately sniffed to detect THP. Since then, 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. Knowing that mousy off-flavor 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 odor by sniffing <ref>Private correspondence with Dr. Paul Grbin by Dan Pixley. 11/2/2017.</ref>.
Tempère et al. (2019) developed what they suggest is a better way to test for THP in wine via oral sensory, specifically as a way to enable panelists who are not as sensitive to THP to detect it during sensory testing. They compared the alkaline strips method to a method where the wine's pH is increased by adding sodium bicarbonate to a pH of 5 and a pH of 7. This mild base is contained in human saliva. At a pH of 5, sensory panelists were more easily able to detect APY and to correctly order the intensity of APY in wine than when they used alkaline strips. For example, the range of detection level for all panelists went from a range of 15 - 300 µg/L to a range of 0.3 - 30 µg/L. At a pH of 7, panelists were not as easily able to detect the aroma of THP. Keep in mind that this test does not reflect the real world tasting of wine since the pH would never be raised during normal consumption, but it could be used by a sensory program as a way to more reliably detect smaller amounts of THP in wine <ref name="Tempère_2019">[https://oeno-one.eu/article/view/2350 Comparison between standardized sensory methods used to evaluate the mousy off-flavor in red wine. Tempère, S., Chatelet, B., de Revel, G., Dufoir, M., Denat, M., Ramonet, P.-Y., Marchand, S., Sadoudi, M., Richard, N., Lucas, P., Miot-Sertier, C., Claisse, O., Riquier, L., Perello, M.-C., & Ballestra, P. 2019. DOI: https://doi.org/10.20870/oeno-one.2019.53.2.2350.]</ref>.

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