The Effect of Temperature on Some Rheological Properties of Wheat Flour Doughs

Abstract

Abstract. Doughs from three flours were sheared between a cone and plate at constant rates in the range 6 times 10‐4‐2 times 10‐2 s‐1. At temperatures between 25 and 40d̀C, the apparent viscosity decreased with increasing temperature and with increasing rate of shear. The effects of the temperature and of the rate of shear were independent one of another, and can be described by an Arrhenius type equation and a power equation, respectively. At temperatures between 45 and 60d̀C, the apparent viscosity increased rapidly with increasing temperature; this is ascribed to starch gelatinization. In this temperature range, the apparent viscosity decreased more rapidly with increasing rate of shear than at lower temperatures. At temperatures between 25 and 45d̀C, the shear modulus decreased with increasing temperature and slightly increased with increasing rate of shear. From the former fact it is concluded that the elasticity of dough has an origin different from rubber elasticity. In this temperature range, the shear modulus can be described by an equation similar to that for the apparent viscosity. At temperatures between 45 and 65d̀C, the modulus increased with increasing temperature, though to a lesser extent than the apparent viscosity. Changes in the rate of stress relaxation are in accordance with the effects of temperature and rate of shear on the apparent viscosity and the modulus.

Modeling of bread baking with a new, multi-scale formulation of evaporation–condensation–diffusion and evidence of compression in the outskirts of the crumb

“…Law established from data acquired on crumb of gas fraction 0.7-0.8 and at ambient temperature (Rask, 1989;Zanoni et al, 1995) m g Kinematic viscosity of gas m 2 s À1 3 Â 10 À5 g Bulk dough viscosity Pa s g o = 450 g f = 4.5 Â 10 6 Bloksma and Nieman (1975) q dm Z Density of dry matter kg m À3 1800 Rask (1989) q w.liq Z Density of liquid water kg m À3 1000 Perry and Chilton (1973) s Tortuosity of liquid phase due to presence of bubbles p/2 Heat transfer is characterized by a global heat transfer coefficient, h bot, and the air temperature under the plate of the oven, T bot .…”

Rheological properties of skim milk gels at various temperatures; interrelation between the dynamic moduli and the relaxation modulus

“…A Weissenberg R 18 Rheogoniometer was used, (a brief description is given here; a more detailed description is given by Bloksma and Nieman [27]). The apparatus consisted of a cone (top) and a plate (bottom), both having a radius of 37.52 ram.…”

The Viscoelastic Properties of Wheat Flour Doughs

“…The fact that two apparently equivalent doughs, proofed to the same height, can produce loaves of significantly different volumes suggests that the temperature-dependent changes that occur during baking may define or determine flour quality. Despite the fact that there is, a priori, no reason to presume that only those changes occurring prior to baking are relevant, little data exist on the fundamental rheological properties of doughs during heating (Bloksma and Nieman, 1975;LeGrys et aI., 1980;Dreese et aI., 1988aDreese et aI., , 1988c. This lack of data may be because of the inherent difficulty in heating a dough mass uniformly while at the same time testing it.…”