The effect of in vitro starch digestibility on glycemic/insulinemic index of biscuits and bread made from non-conventional wholemeal/wholegrain flour mixtures.

BACKGROUNDCarbohydrates as starch are a staple part of the Mediterranean diet. Starch is digested in the small intestine and the resulting glucose is absorbed into the blood, eliciting an insulin response. The digestion and absorption kinetics (rapid or slow) depends on starch structure. OBJECTIVETo study the relationship between the in vivo glycemic and insulinemic index and the in vitro digestibility characteristics of six bakery products, made from non-conventional wholemeal/wholegrain flours. METHODSWe analyzed in vitro the rapidly- and slowly- available glucose (RAG and SAG), the rapidly- and slowly- digestible starch (RDS and SDS), and the resistant starch (RS) fraction of the six wholemeal/wholegrain products and one white type of bread. The glycemic and the insulinemic index (GI and II respectively) were estimated by in vivo testing in a group of eleven healthy individuals. RESULTSThe GI of the wholemeal/wholegrain flour biscuits and breads were low, (range 28{+/-}3.2 to 41{+/-}3.9, Mean{+/-}SEM) correlating with the II. RAG positively correlated with both GI and II, with fiber having a marginal correlation. CONCLUSIONSOur findings indicate that both conventional and non-conventional wholemeal/wholegrain bakery products have low GI and moderate II, correlating to in vitro starch digestibility and the type of processing.