Physical Properties of Mizu-Gyoza (Shui Jiao Zhi)

Abstract

Effects of water, sodium chloride, lard and protein on the mechanical properties of mizu-gyoza (shui jiao zhi) were investigated by using a rheometer. (1) Tensile strength of sheeted dough decreased with an increase of added water, while its extensibility increased with added water. Adhesiveness increased remarkably by the addition of water above 40%. Both cutting strength and adhesiveness of cooked sheeted dough decreased with water content. (2) Tensile strength and extensibility of sheeted dough increased with NaC1 content. Cutting strength of cooked sheeted dough, adhesiveness of sheeted dough and cooked sheeted dough provided maximum values around 4% NaCl. (3) Tensile strength of sheeted dough decreased slightly, but the extensibility increased remarkably with lard content. Adhesiveness showed a maximum value at 20% of lard. After cooking, cutting strength decreased but adhesiveness was almost constant with increasing lard content. Dynamic modulus and viscosity decreased with lard content. (4) The tensile strength and extensibility of sheeted dough, and cutting strength of cooked steeted dough increased with an increase of protein content. Adhesiveness increased up to 10.3% of protein for sheeted dough and up to 11.3% for a cooked steeted dough but decreased above these content of protein. (5) Quadratic equations for various mechanical parameters were obtained in order to predict the relation between ingredient ratio and mechanical properties. Fourty to 40.5% of added water, 4% of NaC1 and 1 to 2% of lard are concluded to be suitable contents for processing and cooking conditions of mizu-gyoza.