Tetrahydropyridine: Difference between revisions

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[[Category:off flavors]]
[[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 wiki. 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)"] Forum thread. HomeBrewTalk. January 2019.</ref>
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 wiki. 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 forum. Published 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 wiki. Accessed May 2020.</ref> 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. December 2018.</ref> THP is a significant concern in [[sour beer]], where these microbes are commonplace, but it may also occur in [[wine]], [[cider]], [[mead]], etc. if wild microbes are present.
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 wiki. Accessed May 2020.</ref> 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. Published December 2018. Accessed 2020.</ref> THP is a significant concern in [[sour beer]], where these microbes are commonplace, but it may also occur in [[wine]], [[cider]], [[mead]], etc. if wild microbes are present.


Best strategies to avoid THP:
Best strategies to avoid THP:
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* For fruit beers/wines: add yeast from an [[acid tolerance starter]] when you add the fruit.
* 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.
* 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 [[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., et al. [https://pubs.acs.org/doi/abs/10.1021/jf0528613 "Mousy Off-Flavor:  A Review."] ''J. Agric. Food Chem,'' vol. 54, no. 18, 2006, pp. 6465-6474.</ref>
* [[Passivation|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.<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.
* In wine, proper usage of [[sulfite]] inhibits the wild microbes that produce THP.


Revision as of 04:18, 22 July 2020

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] It most often forms around the time of packaging, when THP production is stimulated by the presence of oxygen +/- fermentable sugar.[4] THP is a significant concern in sour beer, where these microbes are commonplace, but it may also occur in wine, cider, mead, etc. if wild microbes are present.

Best strategies to avoid THP:

  • Avoid excessive 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

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

References

  1. ↑ "Tetrahydropyridines." Lambic.info wiki. Accessed May 2020.
  2. ↑ THP (Tetrahydropyridines). HomebrewTalk forum. Published 2019. Accessed 2020.
  3. ↑ "Tetrahydropyridine." Milk the Funk wiki. Accessed May 2020.
  4. ↑ Tyers B. Cereal killer — why thp is bad for beer and what you can do about it. Good Beer Hunting. Published December 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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