Alpha and Beta Amylase
Alpha- and beta-amylase are the core starch-conversion enzymes in malt, but in sorghum they do not appear in the same balance as barley. That single difference explains a large share of sorghum brewing behavior: conversion speed, sugar profile, fermentability, and the need for process control during mash design.
What This Page Is Built to Answer
- What does each enzyme do during mashing?
- How is sorghum enzyme balance different from barley?
- What did Bard's quality data show for alpha activity and conversion readiness?
- How should brewers interpret low beta-amylase in sorghum malt?
Functional Difference
Alpha-amylase cuts starch chains internally, creating a mix of shorter sugar chains (dextrins) and fermentable sugars. It is the dominant enzyme in sorghum malt.
Beta-amylase works from chain ends and releases maltose — a highly fermentable sugar. In barley this enzyme is usually stronger relative to alpha-amylase. In sorghum it is lower, and part of the activity is released from inactive locked-in forms (bound forms) during germination rather than freshly built the way barley does.
Sorghum-Specific Pattern
Research and archive synthesis indicate sorghum malt typically shows:
- Alpha-amylase as the dominant amylolytic activity
- Wider lot-to-lot variation by cultivar and crop year
- Lower beta-amylase contribution than barley malt
- More sensitivity to germination timing around the 96-hour peak window
In practice this means sorghum mashes can produce a different sugar profile than barley at similar gravity targets. Brewers often compensate with process design and enzyme support.
Bard's Data Snapshot
Montana State Lab data for Bard's sorghum malt (March 2019):
- Alpha-amylase: 10.1 to 10.5 D.U. (Dextrinizing Units — a measure of starch-cutting enzyme activity)
- Diastatic Power: 102.1 to 114.1 Lintner (overall enzyme strength; values above 100 L are workable for enzyme-assisted brewing)
- Extract (coarse grind dry basis): 52.7 to 53.3%
- Filtration: slow
These values indicate active conversion potential in the malt, but not a barley-like enzyme balance. The brewery process at Left Hand also used external enzymes, which reduced dependence on malt-only beta-amylase contribution.
Practical Brewing Implications
- Favor mash protocols that support sorghum starch softening (gelatinization) before relying on enzymatic conversion.
- Monitor fermentation completion (attenuation) and how much starch converts to fermentable sugar lot to lot; equal OG does not guarantee equal fermentability.
- Treat alpha-amylase trend as a leading quality indicator for extract stability.
- Use FAN (Free Amino Nitrogen — protein-derived nutrients available to yeast) and fermentation behavior as cross-checks when enzyme profile shifts.
Common Failure Modes
Spec drift - Accepting lots without trend checks creates hidden inconsistency.
Process drift - Small timing or temperature changes compound into material performance loss.
Feedback lag - Waiting for finished-beer problems before adjusting malt decisions increases cost and rework.
Practical Win Conditions
Use clear release criteria, monitor lot trends, and close the loop between malt metrics and production outcomes. Teams that do this get stable quality and fewer downstream surprises.
Key Takeaway
Use this page as a decision aid: define the target outcome, check the process variables, and validate with quality data before scaling.
Quick Reference
| Decision Area | What to Check | Why It Matters |
|---|---|---|
| Input quality | Lot specs and source consistency | Prevents avoidable downstream variability |
| Process control | Temperature, timing, and handling discipline | Keeps results repeatable batch to batch |
| Outcome check | Performance and sensory fit to purpose | Confirms the malt is usable in production |
Source Notes / Confidence
- Strongly supported: Alpha dominance in sorghum and bound-form beta-amylase context (research synthesis)
- Strongly supported: Bard's alpha-amylase and DP measured values (Montana State archive report)
- Partially supported: Direct beta-amylase numeric ranges in Bard's lots (not consistently reported in available archive files)
- Needs review: Lot-level action thresholds Bard's used for alpha/beta ratio acceptance