Strategies for the manufacture of resistant starch

Starch not hydrolyzed in the small intestine is considered to be enzyme-resistant starch (RS). Because individuals differ in their ability to digest starch, there is no absolute distinction between RS and digestible starch. A method for in vitro determination of RS should be validated using a human population average value. In any starch material, the constituent molecules will have a range of susceptibility to amylolytic activity in vitro. For a starch or starch-containing ingredient it is possible to alter this range by judicious selection of processing conditions to increase the proportion that tests as RS. The starch material will also have a range of thermal stabilities before and after processing which may or may not reflect the range of susceptibility to hydrolysis. The manufacture of RS may be thought of as enhancement of the proportion of the starch that tests as RS. To compare the effect of different processing schemes, it is critical to stipulate the method used to estimate RS content. This review focuses on strategies for increasing the proportion of types 2 and 3 RS in a starch-containing ingredient. Special emphasis is given to increasing RS levels of granular starch. (C) 2001 Elsevier Science Ltd. All rights reserved.