Effects of hydrothermal processing of buckwheat (Fagopyrum esculentum Moench) groats on starch enzymatic availability in vitro and in vivo in rats

Content of total starch (TS), rapidly digested starch (RDS), slowly digested starch (SDS), resistant starch (RS) and retrograded starch (RS,), apparent amylose and total amylose were studied in raw (uncooked) and in hydrothermally treated buckwheat groats. Hydrothermally treated buckwheat samples contained 4.0-4.3% of retrograded starch (dmb). This means that about 5.5% of the TS present in the samples appeared as RS,. There was a good correlation between the retrograded starch by the in vitro method and the undigested starch in iiivo in rats (r=0.91, P<0.01). In untreated greats and in greats dry-heated to 110 degrees C there was significantly less RDS than in hydrothermally treated samples. Approximately one half of the raw great starch was not digested within 120 min in vitro. Buckwheat greats prepared by using the traditional procedure of cooking before dehusking followed by warm-air drying, have less than 48% (dmb) of rapidly available starch, in comparison to white wheat bread, where the corresponding value is almost 59%. Buckwheat greats starch with a reduced rate of digestion could be a possible complement to or a substitute for common carbohydrate sources. (C) 1998 Academic Press.