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Acetaldehyde (ass-eh-tal-deh-hyde)

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  • Naturally occurring organic compound that is found in everything from ripe fruit to coffee to wine.
  • Found in most fermented products such as Yogurt, Sauerkraut, Kombucha.
  • Found in almost every beer at different thresholds. Mostly at lower thresholds that are undetectable.
  • Detectable by most people. 15 out of 22 in Brulosophy Exbeeriment.
  • Identifiable by some, less than majority of 15 could identify it. 6 correctly selecting it while 3 believed it was DMS, 2 chose astringent, 2 thought it was metallic, and 2 thought it was oxidized.

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ACETALDEHYDE – Aroma and Flavor

At various threshold levels in beer:

  • Low thresholds – light apple fruitiness. Acceptable in American Lagers, American Lite Lagers, International Pale Lagers, International Dark Lagers and Lichtenhainer.
  • Higher thresholds – pungent green apple (like Jolly Ranchers). A flaw in all beers except Kellerbier.
  • Oxidized/Stale beer – green apple, latex paint, leaves, raw pumpkin, bug spray
  • Bacterial contamination – green apple, sour apple

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ACETALDEHYDE – Causes

  • Stuck or Incomplete Fermentations - Yeast produces acetaldehyde as an intermediate compound in the conversion of glucose to ethanol. However, in a healthy fermentation, the yeast fully converts the vast majority of this compound to alcohol so that any residual amount falls below the flavor threshold. If the fermentation is less than optimal, the conversion of acetaldehyde to alcohol may remain incomplete, and too much will remain in the final beer.
    • Acetaldehyde and Diacetyl often appear in the same beer.
  • Oxidation/Staling - oxidation of alcohol, such as may happen when exposing fermented homebrew to oxygen.
  • Poor Sanitization – Bacteria oxidize alcohol

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ACETALDEHYDE – Fixes in beer

  • Proper yeast management (no stuck or incomplete fermentations)
    • Pitch an appropriate amount of healthy yeast. Make a starter.
    • Fully oxygenate wort at pitching.
    • Correct yeast, not to flocculant.
    • Proper fermentation temperature.
    • Allow time for conditioning (weeks to months depending on style).
    • Add yeast nutrients.
  • Avoid racking beer off the yeast before fermentation is complete. Wait a few days after reaching terminal gravity before racking beer.
  • Avoid introducing oxygen into your beer after fermentation (kegging and bottling).
    • Purge headspace with C02.
    • Keep the airlock filled with liquid.
  • Maintain flawless sanitation practices.

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ACETALDEHYDE – Carcinogen

•In 2009, the International Agency for Research on Cancer (IARC) upgrade cancer risk from “possible causes cancer” to “causes cancer”.

•Now belongs to the same risk class (Group 1) as asbestos and tobacco.

•Limited exposure is recommended.

•If time permits (4:28), play this: Alcohol, how much is safe?

•Ways to limit exposure: Limit exposure to Acetaldehyde

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