Paste and gel properties and in vitro digestibility of Tef [Eragrostis tef (Zucc.) trotter] starch

Properties of tef starch from five varieties were compared with commercial maize starch. In most tef varieties the paste clarity (measured as % T) was similar to that of maize starch, but the paste was visually less white in colour. Tef starch gel texture was short and in most varieties was slightly firmer than that of maize starch. Tef starch adhesiveness was less than maize starch. Retrogradation extent of tef starch evaluated, as % gel syneresis under storage at 4degreesC and -18degreesC at 3, 7, 10 and 21 storage test days, was lower than that of maize starch. Storage with three freeze-thaw cycles (-18degreesC 24 h; 23degreesC 6 h) gave a similar trend. In tef starch initial digestion by alpha-amylase and hydrolysis by mild HCl treatment was slightly higher than in maize starch, probably in part because of the smaller granule size and higher amorphous portion of tef starch. Alpha-amylase degradation of tef starch granules was by surface erosion, probably due to the absence of surface pores in the granules.