[Alpha-amylase inhibitors and soluble dietary fiber in rye: partial purification and effect on postprandial glycemia].

The protein inhibitor of the alpha-amylase (D-type) and the soluble arabinoxylan of rye (Var. Clou) were isolated from flour and bran, respectively. The isolation of the alpha-amylase inhibitor involves the extraction of rye flour in aqueous CaCl2-solution (2 x 10(-3) M containing the hemicellulase preparation Veron HE (2 g/100 g flour), dialysis and lyophilization (preparation I) and further fractionation with ammonsulfate, using the fraction 20-50% for isolation (preparation II). The arabinoxylan isolation is carried out using extraction of rye bran in 80% ethanol (80 degrees C), centrifugation, aqueous extraction of the sediment, dialysis and lyophilization (preparation I). The further purification using the precipitate of the fraction 20-50% leads to preparation II. The alpha-amylase inhibitor preparation II and the arabinoxylan preparation II were applied in a diet containing wheat starch and casein and fed to diabetic and healthy rats (Levis and Wistar). The postprandial increase of glucose was determined. It was detected that the postprandial increase of glucose is influenced neither by the alpha-amylase inhibitor nor by the soluble arabinoxylan in comparison to the control experiments. However, the alpha-amylase inhibitor of wheat significantly decreases the postprandial increase of glucose. The application of a test meal with alpha-amylase inhibitor of rye to health and diabetic of type-II-volunteers showed no variation of the blood glucose values. The reduction of the increase of glucose by the soluble beta-glucan of oat cannot be confirmed for the soluble arabinoxylan of rye. We conclude that the effect of the alpha-amylase inhibitor as well as the soluble pentosan or glucan has to be examined for each cereal species.