Abstract:

The viscosity and the rheological properties of common and tartary buckwheat starches were analyzed using rapid viscosity analyzer and AR-G2 rheometer during the gelatinization, respectively. Meanwhile their swellability, retrogradation, freeze-thaw stability, and transparency were also measured. The results showed that the gelatinization temperatures of the two buckwheat starches were both higher than that of mung bean, but lower than those of rice and wheat starches; the expansion process of tartary buckwheat starch was similar to that of mung starch, while the expansion process of common buckwheat starch was similar to that of wheat starch; the transparency of buckwheat starch paste was higher than that of rice starch paste but lower than those of wheat and mung starch pastes; the freeze-thaw stability of buckwheat starch paste was higher than that of rice starch paste but lower than that of mung bean starch paste; buckwheat starch paste had nice retrogradation stability; and the apparent viscosity of buckwheat starch paste was found to be irreversible with an open-ended hysteresis loop, indicating buckwheat starch paste belongs to the pseudoplastic fluid in non-Newtonian fluids, whose rheological curve accords with Sisko equation.

Key words: starch, buckwheat, gelatinization