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Beta, Rooney & Waniska 1995: Malting Characteristics of 16 Sorghum Cultivars

Sixteen sorghum cultivars malted under one method, and the cultivar-to-cultivar spread is the finding: α-amylase activity ran 25 to 183 U/g — a seven-fold range — and two cultivars reached α-amylase levels similar to a commercial barley malt. The published sibling of this site's Madison screening, and an honest wrinkle for the conversion doctrine, stated here on purpose.

This is an external paper. The record of authority is Beta, T., Rooney, L.W. & Waniska, R.D., Malting Characteristics of Sorghum Cultivars, Cereal Chemistry 72(6):533–538 (1995), published by the AACC — publisher's archive PDF. No DOI exists for this back-issue paper. The figures on this page come from the published abstract; this page adds the brewing-side reading and reproduces no tables.

What the study did​

Sixteen sorghum cultivars were malted under a germinator method (with six of them also malted by a jar method for comparison), and the malts were analyzed for diastatic power (SDU basis), α-amylase activity, and malting loss. It is the same experimental shape as this site's USDA Madison screening — many named cultivars, one standardized schedule — from an independent lab, three decades earlier.

What it reports​

  • α-amylase activity ranged from 25 to 183 U/g across cultivars by colorimetric assay — a roughly seven-fold spread from one malting method.
  • Two cultivars reached α-amylase activity similar to a commercial barley malt.
  • Diastatic power (SDU) correlated positively with α-amylase activity.
  • The jar method produced malts with dry-matter losses of 8–19%.

What these numbers mean for brewing​

  • Cultivar choice moves the enzyme numbers — a lot. A seven-fold α-amylase spread from a single malting schedule is the same lesson the Madison screening taught with extract (31–68%) and DP (19–46 ASBC): "sorghum" is not a specification, and naming the cultivar is the only way any malting result means anything.
  • The honest wrinkle: α can get close to barley. Total conversion cannot — so far. Two cultivars matching commercial barley malt on α-amylase is the strongest published data point for native sorghum enzyme potential, and this site states it deliberately. Read it beside Muoria 1998: total diastatic power — which needs the β-amylase side sorghum malt lacks — still ran roughly 27-fold below barley. α-amylase liquefies; saccharification needs the rest of the enzyme system. A cultivar strong on α is a genuinely interesting malting material and still not a self-converting one.
  • This is why the doctrine says "no assigned job" instead of "no activity." The site's external-enzymes position has always acknowledged that native activity is real and measurable — this paper is part of why. What no published study yet shows is a cultivar-plus-malting combination reliable enough, lot to lot, to plan conversion around. That exact gap is Research Ask 9, and a result closing it is a named trigger in the position's "what would change our position" record.

Honest limits​

Abstract-level extraction: units matter here more than usual — α-amylase in U/g by colorimetric assay and DP on the SDU basis do not convert casually to the ASBC degrees used in Muoria 1998 or the Madison screening; compare shapes and ratios across studies, not raw numbers. The cultivars are 1990s Texas-program materials, not today's commercial hybrids. And α-amylase parity with barley malt on two cultivars is a bench finding about one enzyme class, not a brewing trial — no wort, fermentation, or beer data backs it.