Digestibility of common native starches with reference to starch granule size, shape and surface features towards guidelines for starch-containing food products

Influence of diverse botanical sources (wheat, maize, waxy maize, cassava, potato, rice or waxy rice) on in vitro native starch digestibility has been investigated. Physicochemical properties (chemical composition, particles size and shape, surface features) of starch granules were determined with a view to explaining digestibility differences between samples. Rapidly digestible starch (RDS), slowly digestible starch (SDS) and resistant starch (RS) contents were measured according to Englyst method. Potato starch was shown to be composed of large rounded granules having smooth surfaces, which explains its slow enzymatic breakdown. Potato starch displayed the highest RS (86%) content and the lowest RDS content (9.9%). Since RS positively influences health and SDS may result in cell, tissue and/or organ damages, potato starch is an ideal starch nutrient. Conversely, waxy rice starch was rich in amylopectin and displayed small diameters and angular shapes, which are both known to facilitate enzymatic starch hydrolysis. It exhibited a near-zero RS content (0.9%) and a high RDS fraction (60%). According to this study, potato starch exhibited the best nutrient profile, followed up in this order by cassava, waxy maize, wheat, maize and waxy rice starches.