Influence of technological processing of wheat grain on starch digestibility and resistant starch content

The grain of six standard wheat cultivars and one high-amylose wheat cultivar was ground and milled to produce common white flour used to prepare bread, biscuits and wafers. Changes in rapidly and slowly digestible starch (RDS and SDS), resistant starch (RS) and fibre caused by different milling and by the preparation of bakery products were observed. Depending on the milling process, RDS ranged from 28.3 to 32.4% of dry matter and SDS from 18.3 to 35.2%. The preparation of bakery products increased RDS by 30–80% to the detriment of SDS. RS comprised on average 6.6% of ground grain, 3.9% of wheat flour and 3.5, 5.9 and 1.0% of bread, biscuits and wafers, respectively. Variance amongst standard wheat cultivars was low, with only the high-amylose wheat showing unique technological and nutritional properties. RS and total starch (TS) were measured using two different methods. TS determinations correlated closely, although the linear regression varied amongst the different matrices. The correlation between RS values measured by the two methods was loose, and no significant linear regression was found. The article brings new information on variability in starch digestibility in cereal products depending on wheat cultivar used for production.