Resistant Starch Formation Following Autoclaving of Buckwheat (Fagopyrum esculentum Moench) Groats. An In Vitro Study

Buckwheat groats (cv. Darja) were autoclaved at 120 °C for 1 h and cooled to room temperature (the temperature decreased to 25 °C in 150 min). A portion was treated further with two additional autoclaving/cooling cycles. A higher number of autoclaving/cooling cycles did not affect the proportion of slowly digested starch (SDS) or resistant starch (RS) fraction found in treated buckwheat but gave a significant ( P < 0.001) rise in the retrograded starch (RS 3 ) amount. In native groat starch, 24.6% of apparent amylose and 28.3% of true amylose was determined. In samples treated with three autoclaving/cooling cycles there was significantly ( P < 0.001) more apparent and true amylose in the starch in comparison to the native sample or to samples autoclaved once. This may be due to gradual cleavage of some glycosidic bonds of starch, resulting in shorter linear chains, which could be then more predisposed to forming both amylose-like helices and more complex aggregates.