Beer Ingredients and Brewing Processes: Malt, Water, Hops and Yeast
Beer Ingredients and Brewing Processes
Advanced-level questions here are causal: a change in ingredient or process produces a specific, predictable change in the finished beer. Expect mash temperature effects on fermentability, water chemistry and mash pH, hop isomerisation and dry-hopping behaviour, and yeast management.
Malt and mash
- Beta-amylase produces maltose, most active around 60-65 C; alpha-amylase dextrinises starch and survives to about 75 C. A low mash rest gives a drier, more attenuated beer; a high rest leaves dextrins and body.
- Crystal malt is stewed while still wet, so its sugars are largely unfermentable and it adds colour and sweetness. Roasted malts are kilned hot and dry, adding colour, dryness and acridity.
- Target mash pH is about 5.2-5.4 for pale beers and 5.4-5.6 for dark beers, whose roast acidity pushes pH down.
Water chemistry
- Sulfate dries the palate and sharpens perceived bitterness; chloride rounds and fills it out. High sulfate-to-chloride ratios suit hop-forward beers, low ratios suit malt-forward beers.
- Residual alkalinity buffers against the acidity of dark grain; too little in a stout gives a thin, acrid beer.
Hops
- Alpha acids isomerise to iso-alpha-acids during the boil; utilisation rises with boil time up to a point, then falls as components are lost.
- Late, whirlpool and dry-hop additions contribute oils (myrcene, humulene, linalool) - aroma and flavour with little bitterness.
- Long, warm dry hops extract polyphenols and harshness; short, cool dry hops keep the profile bright.
Yeast and fermentation
- Pitch enough viable yeast, aerate at pitch, and control temperature. Warm fermentation and underpitching both raise ester levels.
- Attenuation and flocculation are strain traits; they decide body and clarity as much as gravity does.
Worked example
A West Coast IPA tastes muddled and harshly astringent for its 65 IBU. Sulfate is 80 ppm and chloride 150 ppm, so malt dominates and the bitterness reads soft; mash pH is 5.6, extracting husk tannins; the dry hop sat warm for ten days. Fix all three: add gypsum to reach roughly 250 ppm sulfate against 50 ppm chloride, acidify to a 5.2-5.3 mash pH, and dry hop for three days at 18 C.
Traps that cost marks
- Equating more hops with more bitterness; late and dry hops add aroma, not IBU.
- Ignoring water chemistry and then blaming the grist for harshness.
- Assuming roasted grains contribute fermentable sugar; they mostly contribute colour and dryness.
- Forgetting cold-side oxygen pickup, which stales a beer faster than anything on the hot side.