A E Staley Manufacturing Company

General Mills Chemicals, Inc.

John W Salter

Saul Rogols

John L Bond

Enlarged granule starch useful as a protective stilt material in microencapsulated coatings to prevent premature rupture of the microcapsules. Starch granules are increased in size by alkali-swelling of the granules in aqueous slurry. The enlarged granules are then crosslinked to aid in preserving the enlarged granular form through subsequent aqueous coating applications and thermal drying steps. A combination of hydrocyclone starch granule sizing and granule treatment employing alkali-swelling and crosslinking substantially improves the yield of usable large granule stilt materials obtainable from prime grade wheat starch, and other bimodal granular starches such as barley and rye.

Enlarged granule starch stilt material for microencapsulated coatings

A wet process for separating certain cereal starch granules according to size, and the new large granule cereal starch made thereby. Barley, rye and wheat starch may be processed according to the invention, and may bbe subjected to further modifications, such as cross-linking, to further improve the properties of the product. Native colloid, prime grade wheat starch slurry is pumped through a series of cyclone-type separators in a wet process system to separate the large granule portion from the small granule portion. These small granules range in size from about 3-10 microns. A recirculation system is provided to get a starch granule fraction comprising 99% by weight large granules ranging in size from about 12 microns to 40 microns, and at least 22% comprising granules which are 22 microns or larger in size. This product has a very large portion of large granules in comparison to prime grade wheat, which normally comprises about 2.5% granules which are 22 microns or larger. The uniformly sized large starch granules derived by the separation process of the invention are particularly useful in anti-offset lithograph powders, and as protective particles in the sensitized surface coating of non-carbon duplicating paper which normally contains microencapsulated ink. In the latter application, the uniform sized cereal starch particles replace scarce arrowroot starch particles to prevent premature rupture of the ink-containing capsules during handling of the sensitized paper. There is also evidence to show an improvement in baked goods attributable to the use of reconstituted flours incorporating the large granule starch of the invention. The smaller, uniformly sized starch granules also have more uses because of their uniform smaller size, particularly as a substitute for rice starch. Wheat, barley and rye starch are suitable base starch materials because they are easily separated into small and large particle fractions. Wheat is the most readily available of these cereal grains, and is therefore the presently preferred base starch.

Growing community of inventors

Westerville, OH, United States of America

John W Salter