Tannin and Non-Tannin Sorghum: The Grain Class That Decides Malting Behavior
A cereal chemist asks this question first, and a brewer inherits the consequences of the answer whether they asked it or not. It is also easy to get wrong by eye, because the classes are not defined by grain color.
The three types
Sorghum is classified by the presence of condensed tannins (proanthocyanidins), which live in a pigmented seed-coat layer called the testa1:
| Type | Pigmented testa | Condensed tannins | Practical reading |
|---|---|---|---|
| Type I | Absent | None | Non-tannin. The class virtually all US commodity and food-grade sorghum belongs to. |
| Type II | Present | Yes — extractable mainly with acidified solvents | Tannin sorghum. |
| Type III | Present, plus pigments in the pericarp | Yes — highest levels | Tannin sorghum, the classic "bird-resistant" material. |
Two things trip people up. First, pericarp color is not the test — a red or bronze sorghum can be tannin-free, and grain color alone will mislead you; the pigmented testa underneath is what matters2. Second, the trait is genetically simple — controlled at the Tannin1 locus — which is why breeding programs could remove it so cleanly3.
Why a maltster and brewer care
Condensed tannins bind proteins — including the amylases malting exists to develop. In malting studies of tannin-containing sorghums, available diastatic power stayed low even after treatment, and malting alone did not undo the enzyme-binding effect; tannin-free sorghum responded to steep improvements that tannin sorghum did not4. For a gluten-free brewer already working with a malt that struggles to supply reliable conversion enzymes, starting from a grain class that actively inhibits those enzymes stacks the deck twice.
Tannins also bring astringency and bind dietary protein — the same chemistry that makes Type III grain unattractive to birds in the field. None of this makes tannin sorghum a defect of nature: it has real agronomic value and its own brewing tradition — Southern Africa's opaque-beer industry was built on it, with its own evaluation standard written for a product that is meant to be opaque and consumed young. That tradition answers different questions than this site does.
The supply reality — mostly good news
If you are buying US-grown grain, the class question is usually already answered: the US sorghum industry bred tannins out of commodity grain sorghum decades ago, and modern US hybrids are overwhelmingly non-tannin5. Food-grade white sorghum goes further — white pericarp, no testa, tan plant — which is why it is the default answer on Agronomy and Supply and why this site's production record runs through white sorghum.
The class question gets real again the moment you leave that lane: imported grain, unnamed lots, forage or wildlife blends, or breeding material of unknown background. There, "is it non-tannin?" belongs on the same acceptance list as germination and mycotoxins — and a supplier who cannot answer it has answered a different question about their lot identity.
Field methods for checking exist — the standard quick screen is a bleach test that darkens grain with a pigmented testa, described in the practical-methods literature6 — but for brewing purposes the better control is upstream: buy named, identity-preserved, non-tannin material, per Cultivars for Malting.
What this site's guidance assumes
Explicitly: every malting schedule, mash protocol, and enzyme recommendation on this site assumes non-tannin (Type I) sorghum. The screening datasets this site publishes and the production history behind its positions are non-tannin-lane work. We hold no side-by-side malting comparison of tannin classes in our own records, and we will not manufacture one from literature — if that comparison ever gets run on this site's protocols, it will be published as what it is.