Emulsions, Microemulsions, and Lyotropic Liquid Crystals - Surface and Colloid Chemistry: Principles and Applications - page 209

vitamin contents per liter

Pantothenic acid (μg) 3500

Biotin (μg) 35

Folic acid (μg) 55

B12 (μg) 4.5

C (mg) 20

The most remarkable observation is that all 22 minerals considered to be essential to
the human diet are present in milk. Some of these are sodium (Na), potassium (K),
and chloride (Cl). The electroneutrality of milk is maintained by free ions (nega-
tively charged to lactose).
The viscosity of milk and milk products is reported to be important in the rate
of creaming. The viscosity of milk increases with decrease in temperature because
the increased voluminosity of casein micelles' temperatures above 65°C increases
viscosity due to the denaturation of whey proteins' pH; an increase or decrease in
the pH of milk also causes an increase in casein micelle voluminosity. Fat globules
that have undergone cold agglutination may be dispersed due to agitation, causing a
decrease in viscosity.
Optical properties provide the basis for many rapid, indirect methods of analy-
sis such as approximate analysis by infrared absorbency or light scattering. Optical
properties also determine the appearance of milk and milk products. Light scatter-
ing by fat globules and casein micelles causes milk to appear turbid and opaque.
Light scattering occurs when the wavelength of light is near the same magnitude
as the particle. Thus, smaller particles scatter light of shorter wavelengths. Skim
milk appears slightly blue because casein micelles scatter the shorter wavelengths
of visible light (blue) more than the red. The carotenoid precursor of vitamin A,
β-carotene, contained in milk fat, is responsible for the “creamy” color of milk.
Riboflavin imparts a greenish color to whey.

9.5.3.5 colloids in the Food Industry
In the processing of foods and additives, rheological and mechanical properties,
which determine end use properties are of primary significance. These properties
are also related to others such as the impact of taste. Taste is the perception on the
taste buds on the surface of the tongue, and colloidal properties will thus have an
important role. Gels are also known to be used in many food products. The stability
of food products is determined by colloidal stability in many systems (Dickinson,
1992; Friberg, 1976).

9.5.3.6 emulsion Stability
The degree of stability of any emulsion is related to the rate of coagulation of two
drops (O/W: oil drops; W/O: water drops). This process means that two oil drops in
an O/W emulsion come close together, and if the repulsion forces are smaller than
the attraction forces, only then the two particles meet and fuse into one larger drop.
In the case of charged drops, an electrical double layer (EDL) will be present around
these drops. A negatively charged oil drop (the charge arising from the emulsifier)