Physical Chemistry of Foods
needed for the reaction is present in low concentration and has to diffuse from another compartment, viz., the air above the foo ...
Note Assuming DS{ to be negligible, this also yields DH{&136 kJ?mol^1. Cf. Table 4.2. These examples may suffice to illustr ...
proportion of collisions of sufficient energy increases with T, and the reaction rate would be proportional to expðEa=RTÞ. This ...
A series of articles on kinetic studies and modeling are in Food Technol. 34(2) (1980) 51–88. including work on experimental pro ...
5 Transport Phenomena The transport of momentum, heat and mass, or in simpler terms the phenomena of flow, convection, heat cond ...
unit N?m^2 ¼Pa). The stress can be normal, i.e., in a direction perpendicular to the plane on which it acts, or tangential, i.e ...
Laminar Flows. These exist in several types, depending on the geometrical constraints. Some examples are shown in Figure 5.1. An ...
simple flow type. Layers of liquid appear to slide over each other. A volume element is sheared, as depicted in Figure 5.2, but ...
plates. Some kind of elongational flow is always involved when a liquid is accelerated or decelerated. Axisymmetric simple shear ...
we have: in two-dimensional hyperbolic flow Tr¼2; in uniaxial axisym- metric flow Tr¼3; in biaxial axisymmetric flow Tr¼6. Any f ...
A long flexible thread tends to align in the direction of flow but periodically folds (as depicted) and stretches again. Inelong ...
local flow velocity is decreasing, but less than proportionally, which implies that the local velocity gradientCis increasing. F ...
some flow geometries, as well as values for Recr. The flow around a sphere relates, for instance, to a sedimenting particle, whe ...
Answer Laminar flow in a Couette apparatus has a practically constant velocity gradient, which makes calculation much easier. To ...
Table 5.2 also gives examples of the viscosity of some aqueous solutions. It is seen that most solutes increase the viscosity, a ...
Dispersions.* When particles are added to a liquid, the viscosity is increased. Near a particle the flow is disturbed, which cau ...
Various quantities are used in relation to the viscosity of dispersions: relative viscosity: Zrel: Z Zs ð 5 : 7 Þ specific visco ...
Intrinsic Viscosity. Table 5.2 gives some values for the viscosity of 20 %solutions; it is seen that for some neutral solutes th ...
Particle shape. In emulsions the particles tend to be almost perfectly spherical, but in other food dispersions spherical parti ...
gradient (or strain rate) applied, or on the stress applied. The ratio of stress over strain rate then is called theapparent vis ...
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