Oat Grain

Traded oats are almost always hulled types — the hull comes off in a dehuller, not in the combine. Naked or hull-less oats exist and thresh free of the hull, but they are a niche commodity with different handling requirements and are not what the bulk oat trade means by oats. Colour is a trade descriptor, with white oats generally preferred for milling and other colours more common in feed channels.

Food processing of oats follows a distinctive sequence. The grain is cleaned and graded, dehulled to separate groats from hulls, and then kilned — a heat treatment that is not optional. Oat groats are rich in lipase, which would otherwise break down the grain oil and turn the product rancid quickly; kilning deactivates it and is what makes stable oat products possible. Kilned groats are then steamed and rolled into flakes, the primary product of the chain, or cut into steel-cut groats or ground into oatmeal.

The hulls separated at the start are a genuine residual: bulky, abrasive, high in fibre and low in feeding value relative to the groat. They are marketed rather than discarded — as a fibre carrier in feed, as boiler fuel, and as an industrial feedstock — but they are a by-product, not a co-product, because the operation exists to recover groats and the hull is what is left.

• Food — dehulled, kilned, and flaked into rolled oats and oatmeal
• Feed — fed whole or rolled, valued as a bulky, safe energy source for horses and ruminants
• Industrial — oat fractions used as ingredients in other manufacturing
• Seed — retained or certified for the next crop

Test weight carries more weight in the oat trade than in most cereals, because a light bushel signals a lot that is thin, hull-heavy, or poorly filled, and predicts a low groat recovery at the mill. Grade standards also count sound cultivated oats, wild oats, other grains, and foreign material, and millers add their own requirements for plumpness, groat percentage, and colour on top of the grade.

The characteristic defects reflect how the crop is harvested and how the grain is built. Thin and unfilled kernels come off the combine with the rest of the lot and dilute it. Hulls damaged in handling expose the groat prematurely. And because the hull is loose, oats carry more light material and dust than other cereals, so cleaning is central to preparing a lot for sale rather than incidental to it.

Oats store in bulk like other cereals, dried to a moisture appropriate to the holding period, then cooled, aerated, and monitored. Two practical differences stand out. The loose hull and low bulk density mean oats take more volume per tonne than wheat or maize, so bin capacity planned on wheat figures will not hold the same weight of oats. And the same light, dusty, low-density material flows and bridges differently, which affects augering, aeration airflow, and the fire and dust-explosion housekeeping around handling equipment.