Fig. 1 shows an important rise of the temperature
from 20.58C at 20 MPa to 66.58C at 300 MPa. with the
homogenizing pressure at the exit of the valve with the
water-jacketed homogenization chamber at 58C. The
strong warming up of the fluid is due to viscous stress
caused by the high velocity of the fluid flow, which is
then impinged on the ceramic valve. This mechanical
energy is partially dissipated as heat in the fluid Mac
Clement, 1999.. Temperature can influence the size of
the droplets produced during homogenization in a
number of ways. Indeed, the viscosity of both the oil
and aqueous phases is temperature-dependent and decreases
with increasing the temperature. Consequently,
the minimum droplet size that can be produced may be
altered because of a variation in the viscosity ratio
hdrhc. Braginsky and Belivitskaya 1996. have shown
the influence of the viscosity of the dispersed and
continuous phases on the maximum droplet size that
can persist during homogenization, dmax is minimum
when hdrhc is approximately 0.1 and 5. The dependence
of the droplet size produced during homogenization
on the viscosity ratio under turbulent flow conditions
is similar in form to that produced in laminar flow
conditions: heating an emulsion usually causes a slight
linear reduction in the interfacial tension between that
oil and water phases, which would be expected to
facilitate the production of small droplets. Indeed, the
Laplace pressure gradient necessary to disrupt the
droplets, DPLs4grd, is proportional to the interfacial
tension g Atkins, 1994.. Therefore, certain types of
emulsifiers like proteins can lose their ability to stabilize
emulsion droplets against coalescence when they are