Muoria 1998: The Diastatic Power Gap — Barley, Millet, Sorghum
This is an external paper. The record of authority is Muoria, J.K., Linden, J.C. & Bechtel, P.J., Diastatic Power and α-Amylase Activity in Millet, Sorghum, and Barley Grains and Malts, Journal of the American Society of Brewing Chemists 56(4):131–135 (1998), doi:10.1094/ASBCJ-56-0131. The full text is paywalled; the figures on this page come from the published abstract, and this page adds the brewing-side reading. Nothing here reproduces the paper's tables.
What the study did
Grains of barley, millet, and sorghum were germinated for two, four, and six days at 14, 18, and 22 °C, and malts were made from each treatment — 198 malts in total, analyzed for diastatic power, α-amylase activity, and saccharification rate. The design matters: this is not one lot of each grain compared once, but a grid of malting schedules, which is what lets the conclusion survive the "maybe they just malted the sorghum badly" objection.
What it reports
- Among the grains, barley carried the highest diastatic power and α-amylase activity, followed by millet, then sorghum.
- Among the malts, mean diastatic power was 116.50 °ASBC for barley, 13.22 for millet, and 4.37 for sorghum — all three significantly different (P < 0.05) per the abstract.
What these numbers mean for brewing
- The gap is structural, not procedural. Nine germination schedules per grain, and sorghum malt's diastatic power stayed roughly 27-fold below barley's. That is the finding behind this site's operating position that native malt enzymes get no assigned job: the conversion capacity a barley brewer takes for granted is simply not in the sorghum malt to be preserved.
- Millet sits in between — and still far short. At roughly 11% of barley's malt DP, millet malt is measurably stronger than sorghum malt and still nowhere near self-converting territory for a conventional mash. This is consistent with how this site treats millet: a real malt with real uses, converted by the same external-enzyme system.
- It agrees with everything else on this shelf. The USDA Madison screening found sorghum DP ranging 19–46 ASBC units across 25 cultivars under a schedule tuned for sorghum — better than this study's mean, and still a fraction of barley's; the Beta 1995 cultivar survey shows the same shape with a nuance on α-amylase worth reading beside this.
Honest limits
Abstract-level extraction: means, not distributions, and the specific cultivars and lots are the study's, not a market survey. Diastatic power units (°ASBC) reflect the ASBC method; comparisons to values measured by other methods (SDU, WK) need conversion care. None of this page's figures establish what any particular modern malt lot can do — that is what a certificate of analysis is for. The claim this paper supports is the doctrine-level one: sorghum and millet malts cannot be planned around for conversion the way barley malt can.