Sorghum Grain

Traded sorghum is grain sorghum — the types grown for their seed — as distinct from forage, sweet, and broomcorn sorghums, which are the same species grown and harvested for entirely different products. Grain sorghum is small, round, and hard, and threshes free of its glumes. Colour ranges from white through red and bronze to brown, and colour is a commercial descriptor rather than a cosmetic one, since it correlates loosely with pericarp and testa characteristics that affect processing.

Some sorghums carry a pigmented testa layer containing condensed tannins; most of the sorghum grown for the international feed trade does not. The trade-off is real in both directions. Tannins deter birds and slow weathering and pre-harvest sprouting in humid conditions, which is why tannin types persist where those pressures are severe. But tannins bind proteins and depress digestibility and palatability, so tannin-free grain is preferred where the lot is destined for feed or for straightforward food use.

Because this is a property of the grain rather than of the field, it travels with the lot and is declared. Where tannin sorghum is a food staple, processing addresses it — decortication removes the outer layers that carry the tannins, and fermentation and other traditional preparations reduce their effect. That processing is real and widespread, but it is a household and small-mill practice more than an industrial commodity pathway, so no tannin-removal product is asserted here.

Feed is the largest single outlet by traded volume: sorghum is fed whole, cracked, or ground, and its energy value approaches that of maize, which is what it is priced against. Food use is dominated by milling into flour and by decortication into rice-like grains, and there are established beverage uses, both traditional opaque beers and industrial brewing. Sorghum is naturally free of gluten-forming proteins, which has opened a specialist food market for it beyond its staple regions.

• Feed — a maize-equivalent energy grain in compound and on-farm feeding
• Food — flour for flatbreads and porridges; decorticated grain cooked whole
• Beverage — traditional opaque beers and industrial brewing adjuncts
• Energy — fermentation feedstock where locally economic

Grading follows the general cereal pattern: moisture, test weight, damaged and heat-damaged kernels, broken material, and foreign material. Weathered, discoloured, and mould-damaged grain is downgraded, and because sorghum stands in the field on an exposed panicle, weathering damage before harvest is a common origin of a poor lot.

Much of the world sorghum crop is harvested and stored in hot climates where the storage insect pressure is severe and the margin for error on moisture is small. Sun drying on prepared surfaces remains the dominant method at smallholder scale, with mechanical drying used in the commercial export chains. Threshing from the panicle, whether by machine or by hand, sets the amount of broken and cracked grain that will go into store, and broken grain is what storage insects find first.

Sorghum is one of the grains where hermetic storage has made the clearest difference. Sealed containers deprive insects of oxygen and hold moisture stable, and they are used from bag scale upward. Conventional bulk storage works too, but depends on getting the grain dry and keeping it dry — a harder task in a monsoon climate than in a temperate one.