Base Malt
Base malt is the foundation of any grain-based beer. It is pale sorghum malt produced at low kilning temperatures — typically 50–65°C — to preserve the enzymatic activity developed during germination. Every other malt type in the grain bill exists to add color, flavor, or other attributes; base malt exists to convert starch into fermentable sugar and establish the light grain character of the finished beer.
For Bard's, base malt was not supplementary — it was the entire grain bill. Burgundy sorghum malt from Missouri Malting made up 97.32% of every batch, with rice hulls added for lautering efficiency. The characteristics of that single base malt defined everything downstream.
What This Page Is Built to Answer
- What is base malt and what does it contribute to brewing?
- What specific sorghum base malt did Bard's use?
- What quality profile did Bard's base malt actually achieve?
- How does sorghum base malt compare to barley base malt?
What Base Malt Contributes
Base malt does three things in the grain bill:
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Starch for conversion — The majority of the grain's weight is starch. With enzyme assistance (from the malt itself and from added commercial enzymes), that starch is converted to fermentable sugars in the mash tun.
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Enzymatic activity (diastatic power) — A well-kilned base malt retains the alpha- and beta-amylase enzymes built during germination. For Bard's, where external enzymes (Amylex, Diazyme TGA) supplemented the malt, enzymatic capacity from the grain was a quality indicator but not the sole conversion driver.
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Flavor foundation — Even at low kilning temperatures, Maillard reactions produce the light grain character, mild sweetness, and clean finish that define a pale lager malt. Sorghum base malt produces a distinct profile: light, slightly earthy, with a characteristic sorghum note that distinguishes it from barley lager malt.
Bard's Production Malt: Burgundy Sorghum
Bard's selected burgundy sorghum as its primary variety. The Left Hand Brewing production recipe used:
- Grain: Burgundy sorghum, 1,650 kg per batch (97.32% of grain bill)
- Rice hulls: 45.36 kg (2.68%) — added to the lauter tun as a filter medium, not for flavor or starch contribution
- Target OG: 10.5°P (degrees Plato)
- Target ABV: 4.7%
- Target IBU: 18
Burgundy sorghum varieties tend to produce higher alpha-amylase activity than white varieties during malting and have lower malting loss — a combination that makes them commercially preferable for base malt production.
Measured Quality Profile
Bard's malt was tested at Montana State University's Barley, Genetics & Malt Quality Lab in March 2019 using official ASBC (American Society of Brewing Chemists) methods:
| Metric | Sample 1 | Sample 2 | Notes |
|---|---|---|---|
| Moisture | 8.67% | 8.13% | Both within storage spec |
| Extract (CGBD) | 52.7% | 53.3% | Coarse grind, dry basis |
| Color | 1.3°SRM | 1.3°SRM | Pale lager range |
| Beta-Glucan | 3.3 mg/L | 0.0 mg/L | Low — typical for sorghum |
| Soluble Protein | 3.6% | 3.6% | Consistent between samples |
| FAN | 38.0 mg/L | 25.6 mg/L | Free amino nitrogen for yeast |
| Diastatic Power | 102.1°L | 114.1°L | Lintner units (ASBC) |
| Alpha-Amylase | 10.1 D.U. | 10.5 D.U. | Diastase units |
| Filtration | Slow | Slow | Characteristic of sorghum |
| Turbidity | ~6.73 NTU | ~6.73 NTU | NTU = Nephelometric Turbidity Units; pooled samples |
| pH | 5.82 | 5.81 | Typical range |
Color in the standard light malt extract range (1.4–2.5 Lovibond equivalent) confirms this as a pale lager base malt. The 2019 diastatic power values (102.1–114.1°L) represent well-malted lots. Filtration speed was classified as "slow" — consistent with sorghum's hull structure and a known characteristic that affects mash run-off management at the brewery.
Sorghum vs Barley Base Malt
Sorghum base malt differs from barley base malt in several practical ways that affect brewing decisions:
- Alpha-amylase dominates — Sorghum produces primarily alpha-amylase during germination. Barley malt has more balanced alpha/beta amylase, with beta-amylase higher in barley. This shifts wort fermentability characteristics.
- Lower FAN — Sorghum malt FAN (25.6–38.0 mg/L in 2019 tests) is lower than typical barley malt FAN values. Yeast nutrition supplementation may be needed.
- Slow filtration — Sorghum wort filters more slowly than barley wort. Rice hulls or other processing aids are commonly used at lautering.
- Starch gelatinization temperature — Sorghum starch gelatinizes at higher temperatures than barley starch, requiring a higher-temperature mash step or enzyme-assisted liquefaction protocol.
- No gluten — The defining characteristic for Bard's application: sorghum contains no barley, wheat, or rye gluten.
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: Burgundy sorghum grain bill (97.32%) and rice hulls (2.68%) from LH production method (archive); Montana State University lab analysis March 2019 (ASBC methods, archive)
- Strongly supported: Target OG 10.5°P, IBU 18, ABV 4.7% (LH production recipe, archive)
- Strongly supported: Alpha-amylase dominance in sorghum malt (Ratnavathi & Chavan 2016, multiple sources)
- Partially supported: Burgundy variety advantages over white (research literature — colored varieties generally show higher alpha-amylase and lower malting loss)
- Needs review: Exact kilning temperature Missouri Malting applied to Bard's base malt (proprietary process, not disclosed)