The viscosity measured as a function of shear rate of the emulsions containing NaCl exhibited
shear thinning behavior (Fig. 2): the viscosity decreasing with increasing shear rate. The emulsion
without salt showed the flow properties close to Newtonian behavior. When considering the influence
of NaCl concentration on apparent viscosity measured after the addition of NaCl to the emulsion for 2
h, the apparent viscosity increased with increasing salt concentration especially at lower shear rate
(Fig. 3). The slope of the relationships between NaCl concentration and apparent viscosity (Fig. 3)
indicates changes of apparent viscosity with salt concentration decreased with increasing shear rate
(0.0238, 0.0078 and 0.0047 for shear rate 1, 10 and 100 s-1, respectively). In the point of process and
product development, the lower shear rate condition (1 s-1) implies to the condition of storage.
0
20
40
60
80
100
0 30 60 90 120 150
Time (h)
Creaming index (%)
0 mM NaCl
50 mM NaCl
100 mM NaCl
0
20
40
60
80
100
0 30 60 90 120 150
Time (h)
Creaming index (%)
0 mM NaCl
50 mM NaCl
100 mM NaCl
(a) Rotor/stator homogenizer (b) High-pressure valve homogenizer
6
Increasing NaCl concentration increased the viscosity of product emulsion during storage (Fig. 3a).
When considering the emulsions at high shear rate (100 s-1) (such as pumping during process,
transportation), the apparent viscosity gave the almost constant value (2-3 mPa.s) with increasing
NaCl concentration (Fig. 3c).