METHOD FOR PURIFYING CRUDE, DRY GRANULAR REACTED COLD WATER SWELLING HYDROXYPROPYL STARCH DERIVATIVES

摘要

A method of purifying crude, cold water swelling hydroxypropylated starch derivatives prepared by reacting propylene oxide directly with granular starch in the presence of a polybasic, water soluble salt of phosphoric acid catalyst, and in the absence of any liquid reaction medium by washing the crude reacted product with a water-alcohol mixture, the water being present in the water-alcohol mixture in a weight ratio of between 0.1 to 0.7 parts per part of alcohol. The method removes the overreacted-highly substituted starch fractions which are not approved for food use, and other by-products which would otherwise limit the use of the crude product in food.