Tetrahydropyridine

Tetrahydropyridine (THP) is a microbe-derived off flavor that tastes grainy like Cheerios or Capn Crunch cereal.

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.

The best strategies to avoid the production of THP are:

1. Avoid excessive oxygen exposure prior to packaging.
2. 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.

See THP on Milk the Funk for more information.