Many researchers reported that the viscosity of starch pastes decreased in the presence of acids (Campbell & Briant, 1957; D’Appolonia, 1972; Sriburi & Hill, 2000 ; Sriburi et al., 1999; Valle´s-Pa´mies et al., 1997). Yamada et al. (1986) reported that the viscosity of pastes for potato starch decreased by adjusting the pH with citric acid or acetic acid, while that for cornstarch was not affected by acids. However, an increase in the viscosity for starch pastes by adding acids has not yet been reported to our knowledge.