RESUMO
The effect of heat treatment at 90, 100, 110 and 120 â for 20 min to sweet potato flour on dough properties and characteristics of sweet potato-wheat bread was investigated. The lightness (L*) and a* of sweet potato flour samples after heat treatment were increased, while the b* were decreased significantly, as well as the particle size, volume and area mean diameter ( p < 0.05). A slight change of the microstructures of sweet potato flour was observed, where the number of irregular granules increased as the temperature increased from 90 to 120 â. Compared with sweet potato flour samples without heat treatment and with heat treatment at 90, 100 and 120 â, the gelatinization temperature and enthalpy change of sweet potato flour at 110 â were the lowest, which were 77.94 â and 3.67 J/g, respectively ( p < 0.05). After heat treatment, gas retention of the dough with sweet potato flour increased significantly from 1199 ml without heat treatment to 1214 ml at 90 â ( p < 0.05). In addition, specific loaf volume of sweet potato-wheat bread with sweet potato flour after heat treatment increased significantly, which was the largest at 90 â (2.53 cm3/g) ( p < 0.05). Thus, heat treatment at 90 â to sweet potato flour could be potentially used in wheat bread production.
