Physical Chemistry of Foods

Question 1 Can you think of methods to decrease convection currents? Answer Convection currents in a quiescent liquid arise beca ...

13.3 SEDIMENTATION The Stokes Equation. By Archimedes’ principle, the forceFBdue to buoyancy and gravity acting on a submerged s ...

Theparticle Reynolds number, given bydvrc=Zc, must be smaller than about 0.1, since otherwise turbulence will develop in the wak ...

volume then yields <d^2 >¼ Snid^5 i Snid^3 i ¼d 532 ð 13 : 25 Þ to be inserted in Eq. (13.24). FIGURE13.10 Schematic examp ...

Sedimentation Profile. The value ofQgenerally is not constant during sedimentation. If all particles have exactly the same size, ...

Hindered Sedimentation. Strictly speaking, Eq. (13.23) is only valid for one particle in an infinite amount of liquid, and not f ...

creaming was chosen so that Eq. (13.24) predicts the same amount of creaming for both series of emulsions. As seen, this was ind ...

single particles by a factor of about 1.8N^1
1/D. The sedimentation also enhances aggregation, since the larger aggregates tend ...

Decreasing of particle size. This is often applied, for instance, to emulsions by use of a high-pressure homogenizer. In many c ...

makesysomewhat higher, since a yield stress tends to be smaller for longer time scales (see Section 5.1.3). A yield stress of 1 ...

centrifugal acceleration and duration, and tube dimensions) be to make the test meaningful? (b) It is generally observed that th ...

The point is of importance because of polydispersity:d 53 decreases during creaming, and thereby Q, as is illustrated in Figure ...

variables are involved and (b) some fundamental problems have not been fully resolved. Nonetheless, useful general rules can be ...

(varicose) waves can develop, as depicted in Figure 13.14b. If now the amplitudeabecomes almost as large asd/2, the film will ru ...

unstable, if the condition d^2 VðhÞ dh^2 <
2 p^2 g R^2 f ð 13 : 30 Þ is fulfilled. HereV(h) is the total colloidal interacti ...

We note in passing that the Vrij theory, as modified by introducing the Gibbs elasticity, is an extension of Gibbs’ explanation ...

internal stress. The latter is simply given by the Laplace pressure (2g/a). The external stress may be due to colloidal attracti ...

Note In principle, the ‘‘equilibrium’’ size of the flat film can also be calculated. Somesample calculationsare in Table 13.1, w ...

many workers (although hardly ever published), the correlation between the test result and coalescence in practice tends to be q ...

FIGURE13.16 Coalescence of protein stabilized emulsion drops. (a) Experimental setup. The coalescence time at the planar oil–wat ...