Effects of Hydrothermal Processing of Buckwheat (Fagopyrum esculentumMoench) Groats on Starch Enzymatic AvailabilityIn VitroandIn Vivoin Rats

Content of total starch (TS), rapidly digested starch (RDS), slowly digested starch (SDS), resistant starch (RS) and retrograded starch (RS₃), 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 RS₃. There was a good correlation between the retrograded starch by thein vitromethod and the undigested starchin vivoin rats (r=0·91,P<0·01). In untreated groats and in groats dry-heated to 110 °C there was significantly less RDS than in hydrothermally treated samples. Approximately one half of the raw groat starch was not digested within 120 minin vitro. Buckwheat groats 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 groats starch with a reduced rate of digestion could be a possible complement to or a substitute for common carbohydrate sources.