Abstract:

The aims of this research were to explore the degree of thermal damage and gelatinization characteristics of wheat
starch as a function of heating temperature and moisture content and to reveal the relationship of the degree of thermal
damage with gelatinization degree and viscosity properties. Total starch, type-A starch and type-B starch extracted from
commercial wheat flour were studied for changes in damaged starch (DS) content, gelatinization degree and starch paste
characteristics after thermal treatment at different temperatures ranging from 30 to 90 ℃ with high and low moisture levels,
respectively. The results showed that there was a significant correlation between thermal damage degree and gelatinization
degree (P ＜ 0.05) which was greatly affected by moisture. At higher moisture contents, increased temperature could result
in greater DS content and gelatinization degree, especially for gelatinization characteristics, while only a small correlation
was observed at low moisture levels. The pasting temperature was slightly increased with increasing heating temperature,
while its viscosity was reduced significantly and the degree of thermal damage exhibited a negative correlation with peak
viscosity (P ＜ 0.05).

Key words: starch, thermal damage, gelatinization degree, viscosity, damage degree