ALPHA-AMYLASE INHIBITORS AND SOLUBLE DIET ARY FIBER COMPONENTS FROM RYE - PARTIAL-PURIFICATION AND INFLUENCE ON POSTPRANDIAL GLYCEMIA

The protein inhibitor of the alpha-amylase (D-type) and the soluble ar abinoxylan of rye (Var. Clou) were isolated from flour and bran, respe ctively. The isolation of the alpha-amylase inhibitor involves the ext raction of rye flour in aqueous CaCl2-solution (2 x 10(-3) M) containi ng the hemicellulase preparation Veron HE (2 g/100 g flour), dialysis and lyophilization (preparation I) and further fractionation with ammo nsulfate, using the fraction 20-50 % for isolation (preparation II). T he 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 p reparation II. The alpha-amylase inhibitor preparation II and the arab inoxylan preparation II were applied in a diet containing wheat starch and casein and fed to diabetic and healthy rats (Levis and Wistar). T he postprandial increase of glucose was determined. It was detected th at the postprandial increase of glucose is influenced neither by the a lpha-amylase inhibitor nor by the soluble arabinoxylan in comparison t o the control experiments. However, the alpha-amylase inhibitor of whe at significantly decreases the postprandial increase of glucose. The a pplication of a test meal with alpha-amylase inhibitor of rye to healt h and diabetic of type-II-volunteers showed no variation of the blood glucose values. The reduction of the increase of glucose by the solubl e 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 cer eal species.