Oat Bran - Screw Press

August 8, 2007

SunOpta markets special flour additives that are produced from oat bran. Their oat bran raw material is a low value by-product that results from processing oats.

Milling the oat bran and heating it, with a hot acid solution, converts the bran into a valuable food ingredient. An outstanding characteristic is that its inclusion improves the palatability of breads that are microwaved just prior to consumption. Heating releases the moisture. The result is a special, fresh-from-the-oven flavor. As a result, fast food chains are a key market for the product.

Part of the manufacturing process requires that the wet bran, following acid treatment, be dried. Over ten years ago Vincent supplied a screw press for this purpose to the SunOpta Kentucky plant. As the manufacturing process was refined, the press failed to dewater the material. The bran definitely wants to hold water.

Press aid, in the form of dried flour, was tried, to no avail.

Bridging in the inlet hopper was addressed by gluing Teflon panels to the sides of the hopper. Unfortunately, solving the bridging problem did not solve the dewatering problem.

The inlet hopper was pressurized in order to evaluate the Supercharger effect. If anything, this blinded the screen even more. In the end the press was abandoned.

Years later, we again tried dewatering this material, this time with a twin-screw press. Periodically opening the cone to discharge accumulated solids showed promise, as did programming the press' VFD to periodically swing through a reversing cycle. Improved performance was achieved, to the extent that large scale testing is justified.

Issue 189