Glossary
Beta acid
A group of hop resins that do not isomerise during the boil and so contribute little bitterness directly, but oxidise slowly to bitter compounds as hops age.
Also called beta acids, lupulone.
Beta acids matter mainly to hop storage and to long-matured beer. Because they contribute bitterness only through oxidation, a hop with a high beta fraction holds its bittering potential differently over time from one with a high alpha fraction.
They also have real antimicrobial activity, which is part of why hops preserved beer long before anyone understood why.
Related
- Alpha acid — The fraction responsible for most beer bitterness.
More vocabulary
ABV · ABW · Alcohol unit · Alkalinity · Alpha acid · Apparent attenuation · Attenuation · Cohumulone · Degrees Lovibond · Degrees Plato
See every term on the glossary index.
Last reviewed 2026-08-16.
Evidence
What BeerHQ knows about this, and how. Every statement carries the state of the evidence behind it rather than being presented flatly as fact.
Hop compounds have genuine antimicrobial activity against many of the bacteria that spoil beer, which is a substantial part of why hopped beer displaced unhopped ale long before anyone understood the mechanism.
Backed by a source
Sources: Brewing: Science and Practice — print; Beer: Tap into the Art and Science of Brewing — print