Correlation between the in vitro starch digestibility and the glycemic/insulinemic index of biscuits and bread made from non-conventional wholemeal/wholegrain flours

Abstract

BACKGROUND: Carbohydrates as starch are a staple part of human diet. Upon starch digestion, glucose is absorbed, eliciting an insulin response. Glucose absorption kinetics (rapid or slow) depend on starch structure. Products made from wholemeal/wholegrain flour cause moderate glycemic and insulinemic responses and support a healthy lifestyle. OBJECTIVE: To review the nutritional value in terms of the in vivo glycemic and insulinemic index and the in vitro digestibility characteristics of six wholemeal/wholegrain commercial bakery products. METHODS: We 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 against one white type of bread. The glycemic (GI) and the insulinemic index (II) were estimated in vivo in a group of eleven healthy individuals. RESULTS: The glycemic indices of the wholemeal/wholegrain flour biscuits and breads were low, (range 28 ± 3.2 to 41 ± 3.9, Mean+SEM) correlating with the insulinemic indices. RAG positively correlated with both GI and II, with fiber having a marginal correlation. CONCLUSIONS: Our 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 type of processing.