Tetrahydropyridine: Difference between revisions

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[[Category:off flavors]]
[[Category:off flavors]]
Tetrahydropyridine (THP) is a microbe-derived off flavor that tastes grainy like Cheerios or Capn Crunch cereal.
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 only produced only by wild microbes like ''[[Brettanomyces]]'' and lactic acid bacteria such as ''[[Lactobacillus]]''. Normal brewers yeast (''[[Saccharomyces]]'') does not produce this flavor. It mainly occurs when bottle conditioning, because the combination of oxygen and fermentable sugar stimulates its production.
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.


The best strategies to avoid the production of THP are:
# Avoid excessive oxygen exposure prior to packaging.
# Add yeast from an [[acid shock starter]] at the time of packaging.


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


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

Latest revision as of 13:27, 15 March 2022

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).[1] However, not everyone can taste these compounds, and some people may enjoy a low amount of THP flavor.[2]

THP is produced by "wild" microbes like Brettanomyces, lactic acid bacteria such as Lactobacillus, and acetic acid bacteria.[3] 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.[4]

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.
  • Passivate all stainless steel parts that come into contact with the wort, beer, wine, etc., and use 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.[5]
  • 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[edit]

Visit the Milk the Funk wiki for more information about THP.

References[edit]

  1. ↑ Tetrahydropyridines. Lambic.info website. Accessed May 2020.
  2. ↑ THP (Tetrahydropyridines). HomebrewTalk website. 2019. Accessed 2020.
  3. ↑ Tetrahydropyridine. Milk the Funk website. Accessed May 2020.
  4. ↑ Tyers B. Cereal killer — why thp is bad for beer and what you can do about it. Good Beer Hunting website. 2018. Accessed 2020.
  5. ↑ Snowdon EM, Bowyer MC, Grbin PR, Bowyer PK. Mousy off-flavor:  a review. J Agric Food Chem. 2006;54(18):6465–6474.
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