Determination of nutritionally important starch fractions of some Turkish breads

By using an in vitro technique that measures the rate and extent of starch digestion, the starch in a food can be classified as rapidly-digestible starch (RDS), slowly-digestible starch (SDS) and resistant starch (RS). The amount of these fractions in rye bread, wheat bran bread and corn flour bread were calculated from the experimentally determined values obtained by controlled enzymatic hydrolysis and measurement of released glucose by colorimetry, using a glucose oxidase kit. Free glucose and total starch analysis were also carried out to calculate rapidly-available glucose (RAG) content and starch digestibility rate index (SDRI) of breads. RDS content of the rye bread was higher than the wheat-bran bread and corn flour bread (P<0.05). SDS contents of all breads were not significantly different from each other. Wheat bran bread was found to have a significant amount of RS (6.6%; on dry matter basis) when compared to the other breads (P<0.05). A significant negative correlation (r=−0.95, P<0.05) was also found between RS content and SDRI value of breads.