Rheological Properties Including Tensile Fracture Stress of Semolina Extrudates Influenced by Moisture Content

摘要

Semolina extrudates were reshaped, immediately after extrusion to form 0.5 mm thick × 2 mm wide × 130 mm long strips. Moisture content (W) was adjusted to 5 to 39/100 (dry basis) equilibrating in desiccators containing saturated salt solutions. The following tensile rheological properties of the prepared samples were determined at room temperature (21-24℃) using a Rheometrics solid analyzer: Young modulus (E), yield stress (σ_y), fracture stress (σ_c) and fracture stain (ε_c). Each of E, σ_y and σ_c was fitted by a semilogorithmically linear function of W with a neg- ative slope. The property ε_c fitted two semilogarithmically linear func- tions: for W < 24.2/100 a line with a positive slope and for W > 24.2/100 a line with near zero slope. Such data for moisture ranges used in con- ventional pasta drying can help to optimize conditions for pasta produc- tion without stress cracking.