Effect of semolina pudding prepared from starch branching enzyme II a and b mutant wheat on glycaemic response in vitro and in vivo: a randomised controlled pilot study

Refined starchy foods are usually rapidly digested leading to poor glycaemic control, but not all starchy foods are the same. Complex carbohydrates like resistant starch (RS) have been shown to reduce metabolic risk factors for chronic diseases such as hyperglycaemia and overweight. The aim of this study was to develop a semolina based food made from a starch branching enzyme II (sbeIIa/b-AB) durum wheat mutant with high RS content and to measure its glycaemic index (GI) in a double-blind randomised pilot study. We report here the amylose, RS and non-starch polysaccharides concentration of raw sbeIIa/b-AB and a wild-type control (WT) semolina. We measured RS after cooking to identify a model food for in vivo testing. Retrograded sbeIIa/b-AB semolina showed higher RS concentration than the WT control (RS = 4.87±0.6 g/100g, 0.77±0.34g/100g starch DWB, respectively) so, pudding was selected as test food. Ten healthy participants consumed ~50 g of total starch from WT and sbeIIa/b-AB pudding and a glucose drink standard. Capillary blood glucose concentrations were measured in the fasted and postprandial state (2h): incremental area-under-the-curve (iAUC) and GI were calculated. We found no evidence of difference in GI between sbeIIa/b-AB pudding and the WT control, but the starch digestibility was a significantly lower than the WT control in vitro (C90 = 33.29% and 47.38%, respectively). Based on these results, novel sbeIIa/b-AB wheat foods will be used in future in vivo studies to test the effect of different RS concentrations and different food matrices on glycaemia.