Rice Bran

Whitening machines abrade the outer layers of brown rice, and everything they take off leaves together as a fine, oily, pale powder. The stream is not homogeneous: the bran layers proper, the aleurone, and the germ come off in the first passes, while later polishing passes yield a finer material sometimes sold separately as rice polish. Broken grain and fine starch inevitably come with it, and how much dilutes the oil content of the whole.

Fresh rice bran is a race against its own chemistry. Lipase liberated by abrasion hydrolyses the oil into free fatty acids, and once free fatty acids climb past what a refinery can economically remove, the bran is worth only what feed will pay for it. Untreated bran can pass that point in a matter of days, and in warm, humid mill conditions considerably faster.

Stabilisation is the answer, and it means heat: extrusion, steaming, or another thermal treatment that denatures the lipase without damaging the oil. It must happen at or very near the mill, because transporting unstabilised bran to a distant plant guarantees arriving with a degraded product. This is why rice bran oil extraction tends to sit alongside large mills rather than at ports, and why bran from small, scattered mills often never reaches the oil industry at all and goes straight to feed.

• Feed — the largest outlet by volume, in compound feeds and aquaculture rations
• Oil — stabilised bran extracted for rice bran oil, with defatted bran returning to feed
• Food — stabilised bran as a fibre and ingredient, and traditional uses such as pickling media
• Industrial — derived fractions including waxes and other minor products

Because bran concentrates the outer part of the grain, it also concentrates what was on or near the surface. Residues, contaminants, and elements taken up by the plant and deposited in the outer layers report to this stream in higher proportion than to the white rice. The regulatory limits that apply to bran in feed and food are its own, and the condition of the paddy the mill bought is visible here more than anywhere else in the chain.

Stabilised bran stores as an ordinary milled product would: dry, cool, protected from insects, and rotated. Unstabilised bran is not stored at all in any real sense — it is moved immediately, and its keeping quality is measured in hours to days rather than months. Bran is fine, light, and dusty, so pelleting is common for feed use, and dust management is part of handling it in volume.