Starch fractions in a population of wholegrain oats (Avena sativa).

Abstract Glycaemic impact depends largely on the rate of starch digestion in cereals. Digestion rate in wholegrain partially intact cereals depends on grain structure. Therefore, we investigated variation in the relative digestibility of carbohydrates in rolled wholegrain oats (Avena sativa) from a breeding population, using a method sensitive to the effects of grain structure. Replicated oat lines (n = 139) and controls were randomised, processed to wholegrain rolled oats, and subjected to in vitro pancreatic digestion to measure rapidly digestible starch (RDS; 0–20 min), slowly digestible starch (SDS; 20–120 min), and inaccessible digestible starch (IDS), which is carbohydrate digested after homogenising at 120 min to eliminate remaining food structure. In most oat cultivars the total potentially digestible starch (TPDS = RDS + SDS + IDS) consisted mainly of RDS and SDS, with a smaller proportion, IDS, surviving beyond 120 min pancreatic digestion. The average and range of the means were: RDS, average m...