Editing Tetrahydropyridine

[[Category:off flavors]]
Tetrahydropyridine (THP) and related compounds can give an "off flavor" that tastes grainy like Cheerios® or Cap'n Crunch® cereal, or at high levels sometimes "mousy" (like rodent urine).<ref>[https://www.lambic.info/Tetrahydropyridines Tetrahydropyridines.] Lambic.info website. Accessed May 2020.</ref> However, not everyone can taste these compounds, and some people may enjoy a low amount of THP flavor.<ref>[https://www.homebrewtalk.com/threads/thp-tetrahydropyridines.661096/ THP (Tetrahydropyridines).] HomebrewTalk website. 2019. Accessed 2020.</ref>

THP is produced by "wild" microbes like ''[[Brettanomyces]]'', [[lactic acid bacteria]] such as ''[[Lactobacillus]]'', and [[acetic acid bacteria]].<ref>[http://www.milkthefunk.com/wiki/Tetrahydropyridine Tetrahydropyridine.] Milk the Funk website. Accessed May 2020.</ref> THP is a significant concern in [[sour beer]], where these microbes are commonplace, but it may also occur in other beverages such as [[wine]], [[cider]], or [[mead]], if wild microbes are present. It most often forms around the time of packaging, when THP production is stimulated by the presence of oxygen +/- fermentable sugar.<ref>Tyers B. [https://www.goodbeerhunting.com/blog/2018/12/18/cereal-killer-why-thp-is-bad-for-beer-and-what-you-can-do-about-it Cereal killer — why thp is bad for beer and what you can do about it.] Good Beer Hunting website. 2018. Accessed 2020.</ref>

Best strategies to avoid THP:
* Minimize oxygen exposure prior to packaging and during packaging. (For beer, see [[low oxygen brewing]] cold-side methods)
* For fruit beers/wines: add yeast from an [[acid tolerance starter]] when you add the fruit.
* For carbonated beverages: Naturally carbonate rather than force carbonate, and add yeast from an [[acid tolerance starter]] at the time of packaging.
* [[Passivation|Passivate]] all stainless steel parts that come into contact with the wort, beer, wine, etc., and use [[water|RO water]] in brewing and reconstituting [[wine kits]]. [[Iron]] is required for THP production, therefore removing sources of iron will reduce or prevent its formation.<ref>Snowdon EM, Bowyer MC, Grbin PR, Bowyer PK. [https://pubs.acs.org/doi/abs/10.1021/jf0528613 Mousy off-flavor:  a review.] ''J Agric Food Chem.'' 2006;54(18):6465–6474.</ref>
* In wine, proper usage of [[sulfite]] inhibits the wild microbes that produce THP.


If THP forms, it typically ages out over a period of months, but it may take longer.

===See also===
Visit the [http://www.milkthefunk.com/wiki/Tetrahydropyridine Milk the Funk wiki] for more information about THP.

===References===