Sorghum Seed Standard 2 (draft): A Sorghum for the Barley Process

A future specification for breeders: a sorghum that could replace barley in the same process. Its starch gelatinizes low enough for a standard mash, and its malt carries enough enzymes of the right types to convert that mash on their own, with no added enzymes and no cereal cook. The same thirteen properties as Seed Standard 1, plus enzymes.

Status: proposed, draft v0.3, never ratified by anyone. A hypothetical specification: it describes a target to breed toward, ahead of today's grain. It covers non-tannin (Type I) sorghum. The standard in use today, with external enzymes, is Seed Standard 1.

The standard

Report every value with its unit, method, moisture basis and germination length.

#	Property	Target	Report it as	Basis
1	Tannin class	Non-tannin (Type I), confirmed by assay	A bleach test for a pigmented testa; ISO 9648 to quantify tannin. Colour is not the test	Tannin and non-tannin sorghum; GFB-SME
2	Extract	As high as the line gives	Extract from the malt's own enzymes in a standard mash, with method, grind and moisture basis. The GFB-SME reference mash adds enzymes, so it would hide what this standard measures	GFB-SME
3	Protein	Declared	Total protein, % d.b. GFB-MSS Profile B proposes 11–14%; the sorghum research direction is protein digestibility, because kafirin cross-linking restricts FAN	GFB-MSS; Kafirin and protein digestibility
4	FAN	As high as the line gives	mg/L at a stated wort gravity, or mg/100 g malt, with the method. The 25 Madison cultivars ran 59–140 ppm across 3- and 4-day germination	Madison screening
5	Colour	Declared	Malt colour and wort colour, each with its unit and method. Pale sorghum malt ran 0.9–2.1 SRM across six lab reports	Reading a certificate
6	Gelatinization temperature	Inside the barley-malt zone, about 136–149°F (58–65°C), so a standard mash opens the starch without a cereal cook. Today's sorghum runs about 154–178°F (68–81°C)	Onset, peak and range, with the method named (DSC or viscometric). "Sorghum's comparatively high starch-gelatinization temperature is a documented constraint in brewing, separate from its enzyme deficit"	Gelatinization; K-State results
7	Haze and filtration	Free-running wort	Wort filtration rate and viscosity first; turbidity in formazin units, with the instrument declared, second	GFB-SME
8	Grain condition	USA No. 1 grade; test weight ≥ 56 lb/bu; moisture ≤ 14%	Grade, test weight, and moisture with its basis; kernel hardness and size declared	GFB-MSS, Part 3
9	Germination	≥ 90% within 3 days, ideally ≥ 95% and even	Germinative energy, with the method and temperature; water uptake at steep-out declared	GFB-MSS, Profile B
10	Mycotoxins	DON ≤ 0.5 ppm; aflatoxin ≤ 5.0 ppb	Method and limit of detection	GFB-MSS, Part 3
11	Gluten status	Gluten-free, on each lot	The test's method and threshold, lot-matched	Lot Reporting Standard
12	Identity and supply	Named, or declared anonymous	Genotype or pedigree, growing locations and crop year, the check cultivars grown alongside, and whether seed is available to repeat the work. "Anonymous grain is a different, lesser class of result"	GFB-SME
13	Flavour	Described	At the pilot-brew stage, in sensory lexicon terms. Line screening leaves it out	Blue Milo #4 and Ivory 7
14	Enzymes	Enough, of the right types, to convert a standard mash with no added enzymes. The screened floor: diastatic power ≥ 30, ideally ≥ 40 °ASBC; α-amylase ≥ 62, ideally ≥ 78 DU, both at 3-day germination; β-amylase reported	Each in the unit its method uses: SDU under SABS 235, or °ASBC. Never convert between them	GFB-MSS, Profile B

Malt it the declared way. Use the GFB-SME reference schedule so results compare: a 26-hour steep at 75°F (24°C) and germination at 75°F (24°C), to a 1:1 acrospire, about 72 hours at bench scale. Declare the kiln. "Where the goal is preserving enzymes, sorghum malt is kilned cooler. That is the correct choice for a malt that must convert its own starch" (GFB-SME).

Read the enzyme targets as rankings. They come from the Madison screening: α-amylase at its 3-day median and upper quartile, and diastatic power at the screening's own working line of 30. They rank a line against published material; they don't prove the malt will convert a mash by itself. Three cautions come with them:

• Germination length moves the numbers. A fourth day raised α-amylase in all 25 Madison cultivars, by 19.2 DU on average, and Beta 1995 germinated for five days. The 3-day targets are a reference point, and shorter than some schedules in use.
• Diastatic power hides β-amylase. Report it on its own.
• Methods don't agree yet. The site's two α-amylase datasets differ by roughly five to ten times, so compare only within one method.

Rank against check cultivars. Grow named check cultivars alongside the lines under test, and rank each line against them as well as within the set. Cultivars "respond differently to the same schedule" (GFB-SME).

How it differs from Standard 1

	Standard 1: today's process	Standard 2: the barley process
Process	External enzymes and a 190°F (88°C) liquefaction step: the process Gluten Free Brewer uses today	A standard single-infusion mash, as barley malt is brewed, with no added enzymes and no cereal cook
Gelatinization	Declared; the liquefaction step clears the whole range	Inside the barley-malt zone, about 136–149°F (58–65°C)
Enzymes	Not required; listed with the barley numbers to ignore	Enough, of the right types, to convert that mash on their own
Extract	Fine-grind extract, as the certificate reports it	Extract from the malt's own enzymes
Protein	9–12%, ideally 9–10.5%, for extract	Declared; protein digestibility is the research direction
Malted how	Production malt, judged on the certificate and a brewhouse trial	A declared reference micro-malting, kilned cooler to keep enzymes
Output	Buy, trial, or pass	A rank against named check cultivars, and a line to breed toward

What would move this to v0.4

1. Craig's review of the fourteen properties and the differences.
2. One α-amylase method the site's datasets agree on, so the enzyme targets stop being method-bound.
3. A gelatinization value, with its method, for each screened line, and a line inside the barley-malt zone.
4. A line that converts a standard single-infusion mash with no added enzymes.
5. A laboratory running the reference schedule on a named set of North American lines, with check cultivars.
6. Review by a sorghum breeder and a cereal chemist.

Version history

• v0.3 — 2026-09-28. Named for what it is: a hypothetical future specification, a sorghum that could replace barley in the same process. Gelatinization now targets the barley-malt zone; enzymes target converting a standard mash with no added enzymes.
• v0.2 — 2026-09-28. Checked against what sorghum malting research and barley breeding programs measure. The same thirteen properties as Seed Standard 1, reported for research, plus the enzyme specification: β-amylase added, SDU accepted. Protein made declared; extract from the malt's own enzymes; filtration and viscosity lead the haze row; germinative energy and grain descriptors named; ranking against check cultivars moved into the reporting rules.
• v0.1 — 2026-09-28. First draft. Seed Standard 1's twelve properties, with GFB-MSS Profile B's targets, the GFB-SME reference malting, and the Madison screening's enzyme data.

Related

• Sorghum Seed Standard 1 (draft): Today's Process: the standard in use today
• Malting Sorghum Specification: the two profiles these targets come from
• Sorghum Malt Evaluation Standard: the reference malting and reporting rules
• Gelatinization: the barley-malt zone and where sorghum sits
• USDA Madison Screening: the 25 cultivars behind the enzyme targets
• SABS / SANS 235: the sorghum malt method behind SDU
• Research Asks