Instant Emulsions - Food Colloids: Self-Assembly and Material Science - page 418

(a) (b)

25 µm 2 5 µm

Figure 2 Confocal micrographs showing (a) the effect of shaking and (b) fork stirring by
hand on the microstructure of instant emulsions of the same formulation

(a) (b)

Figure 3 Confocal micrographs of an instant emulsion containing 1 pbw caseinate, 1 pbw
lecithin, 2.75 pbw CWS, 50 pbw sunflower oil, 45 pbw water, 1.2 pbwNaCl and
0.65 pbw buffer salts, as well as (a) 0.5 pbw guar gum or (b) 1.33 pbw guar gum

on the final oil droplet-size distribution can be seen in Figure 3, where for the
two systems identical shearing rates and times were employed. The mechanism
by which the final droplet size is formed is probably dominated by droplet
break-up in this case. But, if thickening happens too quickly, the emulsion is
difficult to form because of too high a difference in the viscosities of the
continuous and the dispersed phases.

28.4 Rates of Hydrocolloid Hydration
Hydration of water-soluble polymers on an industrial scale is often aided by
pre-dispersion in a non-solvent (e.g., oil). The mixing times are typically tens of
minutes at elevated temperatures. Here we are concerned with cold hydration in
the time frame of tens of seconds. Efficient viscosifying can be achieved in two
ways - namely by swelling of particles (e.g., with starch) or dissolution of
polymers (e.g., with xanthan gum, guar gum, etc.).
Starches have been designed over the past few decades to serve this purpose,
either in the form of pre-gelatinized starch, or cold-water-swelling starch
(CWS). Pre-gelatinized starches are particulate materials, as a result of the
cooking and drying processes employed in production; they are irregularly