Buckwheat Starch: Structure and Characteristics – A Review

Buckwheat, which contains high nutritional values of protein, dietary fiber, phenolic compounds and minerals, is a major pseudo-cereal for processing functional foods, especially the Japanese buckwheat noodles (soba noodles). In buckwheat flour, starch is a main component which plays an important role in the functional properties of end-use food products. Buckwheat starch granules were spherical, oval and polygonal in shape and granule size distribution ranged from 2 to 6 μm. The apparent amylose content of buckwheat starches varied from 21.1 to 27.4%, while the actual amylose content ranged from 16 to 18%. X-ray diffraction pattern of buckwheat starches was the typical A-type crystal with 38–51% crystallinity. The gelatinization temperatures of buckwheat starch were 57.8–64.3°C for onset (To), 63.7–70.8°C for peak (Tp) and 70.8–85.8°C for complete (Tc) temperatures, and H values ranged from 2.14 to 15.0 J/g. Buckwheat amylopectin showed longer average chain length and larger amount of long chain than did the cereal amylopectins, while buckwheat amyloses were slightly larger than maize and rice amyloses, but similar to wheat and barley amyloses. The -amylolysis limits of buckwheat amylopectins and amyloses were similar to those of the other cereals. The pasting characteristic studies showed that buckwheat starches had similar peak viscosity, higher hot and cool paste viscosities and higher resistance to shear thinning than did wheat starch. These characteristics of buckwheat starches are considered to contribute significantly to the texture and quality of buckwheatbased food products. _____________________________________________________________________________________________________________