COMPARISON OF IN-VITRO AND IN-VIVO MEASURES OF RESISTANT STARCH IN SELECTED GRAIN PRODUCTS

The objectives of this research were to determine and compare resistan t starch (RS) in typically consumed grain products using an in vivo an imal model and two in vitro methods, and to determine the effect of pr ocessing for consumption on RS. Home-prepared cake, cookies, and muffi ns, and commercially processed white bread, corn cereal, and oat cerea l were studied. Mean (+/- standard deviation, n = 6) RS content of the se foods, determined using the colectomized rat, was 0.6 +/- 0.1% (unp rocessed) and 1.1 +/- 0.7% (processed). Processing did not change RS i n the two cereals. Starch remaining in the fiber residue was not simil ar to that in the in vivo measure of RS. In an in vitro system, develo ped to simulate gastrointestinal digestion, varying pancreatin (but no t pepsin) treatment for 1-5 hr was required to obtain values comparabl e to those of the in vivo starch bioavailability. Low bacterial counts (approximate to 20% of rat fecal concentration) in the ileal excreta and a continual monitoring of starch bioavailability from canned peas verified minimal. microbial degradation of RS and indicated that the c olectomized rat was a suitable model for RS studies. Our analyses sugg est traditional grain products may provide 4-6 g of RS/day due to cons umption levels.