49 Cross-linked, type RS(4) resistant starch: Preparation and properties.

K. S. Woo, M. S. Shin, and P. A. SEIB. Dept. of Grain Science and Industry, Kansas State University, Manhattan, KS 66506.

Distarch phosphates with 0.4–0.5% phosphorus have been prepared, and they contain both slowly digested starch (SDS) and resistant starch (RS(4)). The modified starches were obtained in quantitative yield, and provided 13–69% of SDS and 18–87% RS(4) measured by pancreatin digestion followed by gravimetric quantitation. Assay with the Prosky dietary fiber method showed distarch phosphates with 9– 99% resistance to alpha-amylase. The RS(4) starches were prepared from wheat, corn, waxy corn, high amylose corn, oat, rice, tapioca, mung bean, banana, and potato starches. The RS(4) products gelatinized in hot water, but gave low swelling power (~3 g/g starch). Distarch phosphates also were prepared with medium swelling power (6–12 g/g starch) in hot water. A medium swelling product made from wheat starch, after 6 cycles of swelling in hot water and oven drying, lost negligible mass and granule integrity. The moderately swelling starches contained 7–20% SDS and 4–41% RS(4). Hamsters fed 10% of the low swelling RS(4) wheat starch in their diet showed significant changes compared to a control group fed cellulose, namely 1) less feed consumption and lower weight gain, 2) an increased blood level of high density lipoprotein (HDL cholesterol) and a decreased level of very low and low density lipoprotein (VLDL + LDL cholesterol), 3) a decreased level of liver cholesterol, and 4) an increased level of colonic short chain fatty acids, especially butyric acid.