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Survey of Starch Particle-Size Distribution in Wheat and Related Species

¹Plant Breeding Institute, Woolley Bldg A20, The University of Sydney, NSW 2006, Australia. Quality Wheat CRC Ltd, Locked Bag No. 1345, North Ryde, NSW 2113, Australia. Phone: +61 2 9351 4594. Fax: +61 2 9351 4172. E-mail: Stoddard@mail.usyd.edu.au or fstoddard@wheatcrc.csiro.au

The existence of a population of small (B-type) starch granules (<10 μm diameter) in addition to the major (A-type) granules presents a problem for starch-gluten manufacture and certain other wheat processes. A survey of starches in 761 accessions of cultivated wheats, ryes, and wild relatives was conducted. Starch was extracted from grains and analyzed for particle-size distribution by laser diffraction. Australian hexaploid wheat cultivars showed 23–50% of starch in B granules. Landraces from Asia extended this range down to 17%. Tetraploid wheats (Triticum turgidum) showed a similar range of 17–47%, and einkorn wheat (T. monococcum) ranges were 23–62%. The range for B-granule content in rye was only 20–40%, while that in triticale and T. tauschii went down to 15%. The results show that there are clear prospects for manipulating the starch particle-size distribution of cultivated wheats.