Changes

Due to the specialized GC/MS equipment needed for measuring forms of THP that most labs do not have, certain answers will be difficult other human sensory-based methods have been developed in the winemaking world. Originally, a "palm & sniff" method was developed to obtaindetect THP where a small amount of wine is rubbed on the palm which increases the pH of the wine and then sniffed to detect THP. Some 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. These strips were prepared in the following way: knowing that mousy off-flavour 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 odour 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. 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. At a pH of 7, panelists were not as easily able to detect the aroma of THP <ref>[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>.  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.