Effects of alkali and acid on dough rheological properties and characteristics of extruded noodles

The effects of alkaline salt (kansui) and lactic acid on the rheological pr operties of wheat hour dough were evaluated using a capillary rheometer and an oscillatory rheometer. The contents of sulphhydryl groups and disulphid e bands in doughs were also determined. Kansui significantly increased the apparent viscosity and storage modulus (G') and decreased the loss tangent, and resulted in the reduction in protein extractability. It appeared that the addition of kansui increased the proportion of solid-like behaviour in dough. Lactic acid had the opposite effect and resulted in a dough with les s shear thinning. The gelatinisation of starch caused a remarkable increase in G' and reduce the difference in G' and tan delta among the samples. The correlation between dough rheology and characteristics of extruded noodles was also discussed. (C) 2001 Academic Press.