Off-Flavour Training with COBrA
We recently hosted an off-flavour training day organized by the Central Okanagan Brewers Association (COBrA) This event brought together various breweries around Kelowna to delve into the intricacies of detecting and understanding the causes of certain off-flavours in beer.
Detecting and understanding the causes of off-flavours in beer is crucial for maintaining high-quality brewing standards. Here are some common off-flavours, how to detect them, and their possible causes:
Diacetyl: This off-flavour can give beer a buttery or butterscotch taste. It's often detected by a slickness on the palate. It can be caused by premature beer racking before the yeast has fully metabolized all diacetyl precursors, certain yeast strains, or bacterial contamination.
Acetaldehyde: Tastes like green apples or freshly cut pumpkin. This off-flavour is usually the result of removing the beer from the yeast too early, which doesn't allow the yeast to fully metabolize acetaldehyde into ethanol.
Sulfur Compounds: These can impart a rotten egg smell. Common in lagers, it can be caused by stressed yeast or poor fermentation practices. Most sulfur compounds will dissipate with time, but others can indicate contamination or issues with water.
Chlorophenols: Detected by their medicinal, band-aid-like aroma, these off-flavours can be caused by chlorine or chloramine in brewing water reacting with organic compounds. Using filtered or treated water can prevent this issue.
Isovaleric Acid: This gives off a cheesy, old hop aroma and can be detected by its very distinct stale, sweaty socks smell. It is often caused by using oxidized hops or poor storage conditions.
Lightstruck: Also known as "skunky" beer, this results from exposure to light and affects beers bottled in clear or green glass more commonly. It's caused by the interaction of light with the hop compounds, breaking them down into sulfur-containing compounds.
Sensory training sessions are invaluable for effectively identifying these and other off-flavours. During these sessions we improve our ability to ensure the quality and consistency of our products.
