The microscope may be used to determine the type of emulsion formed.
If the oil is dyed red, a red field with clear globules indicates a water-in-
oil emulsion; red globules in a clear field show an oil-in-water emulsion.
Sometimes a multiple emulsion is obtained, i.e., a dispersed phase within a
dispersed phase. The only means of identifying a multiple emulsion is by
the microscope.
Some food emulsifiers. Seifriz has reported that "olive oil stabilized
with sodium oleate, sodium stearate, gelatose, gum arabic, albumin, lecithin,
saponin, senegin, smilacin, or plant juices (cell sap and protoplasm) forms
oil-in-water emulsions, while the same oil stabilized with casein, gliadin,
cholesterin, or cephalin forms water-in-oil emulsions." Seifriz has also
reported that with casein as the emulsifier the following oils all gave water-
in-oil emulsions: olive, castor bean, poppy seed, sperm, and cod-liver oil.
Linseed oil forms with casein a dual emulsion with the water-in-oil type
predominating. Lecithin favors the formation of oil-in-water emulsions,
whereas cholesterol favors water-in-oil emulsions. Saturated casein solu-
tions with common food fats tend to form water-in-oil emulsions.
In food preparation, various fats and oils are used in the formation of
emulsions. Oils commonly employed are cottonseed, corn, olive, and pea-
nut. The fats include butter, lard, Crisco, Snowdrift, and others. In a
cake batter there are several emulsifiers: the casein of milk, egg yolk, egg
white, and the glutenin, gliadin, and starch of the flour. When equal quan-
tities of fat or oil and emulsifying agents were used, the types of emulsions
formed varied, depending on the emulsifier used and whether the oil was
added to the emulsifier, or vice versa.
With egg yolk all the oils and fats gave a very stable emulsion of the
oil-in-water type. With egg white as the emulsifier, oil forms an oil-in-
water emulsion. Fig. 26 shows an emulsion of corn oil and egg white.
When the oil is added gradually to the egg white, a foam as well as an
emulsion is formed. The large white spheres are air bubbles. The oil is
colored red and in the photomicrograph shows black. The illustration also
shows that the oil is adsorbed in the film or layer at the interface between
a liquid and a gas.
When a given weight of butter is added gradually to an equal weight
of egg white, an oil-in-water emulsion is formed. With the last additions
of the butter the emulsion may break. If beating is continued, a water-
in-oil emulsion may form. In melting butter the curdy part containing
the casein settles to the bottom of the container and consequently is usually
272
EMULSIONS
the last portion to be added to the egg white. It may have some effect
upon the reversal of the emulsion. Sometimes onl3^ an oil-in-water emul-
sion forms. Whether this is due to the salt or casein content of the butter
or to the temperature maintained is not known. The emulsion obtained
when egg white is added to the melted butter may be a water-in-oil or
an oil-in-water.
Page 219
Presented as published in 1932. Historical recipes may not meet modern food-safety standards. Cook from the modern interpretation, not the original instructions.
AI-modernized reading of the original text
A modernized reading is not available for this page yet. You are seeing the original text.
The microscope may be used to determine the type of emulsion formed.
If the oil is dyed red, a red field with clear globules indicates a water-in-
oil emulsion; red globules in a clear field show an oil-in-water emulsion.
Sometimes a multiple emulsion is obtained, i.e., a dispersed phase within a
dispersed phase. The only means of identifying a multiple emulsion is by
the microscope.
Some food emulsifiers. Seifriz has reported that "olive oil stabilized
with sodium oleate, sodium stearate, gelatose, gum arabic, albumin, lecithin,
saponin, senegin, smilacin, or plant juices (cell sap and protoplasm) forms
oil-in-water emulsions, while the same oil stabilized with casein, gliadin,
cholesterin, or cephalin forms water-in-oil emulsions." Seifriz has also
reported that with casein as the emulsifier the following oils all gave water-
in-oil emulsions: olive, castor bean, poppy seed, sperm, and cod-liver oil.
Linseed oil forms with casein a dual emulsion with the water-in-oil type
predominating. Lecithin favors the formation of oil-in-water emulsions,
whereas cholesterol favors water-in-oil emulsions. Saturated casein solu-
tions with common food fats tend to form water-in-oil emulsions.
In food preparation, various fats and oils are used in the formation of
emulsions. Oils commonly employed are cottonseed, corn, olive, and pea-
nut. The fats include butter, lard, Crisco, Snowdrift, and others. In a
cake batter there are several emulsifiers: the casein of milk, egg yolk, egg
white, and the glutenin, gliadin, and starch of the flour. When equal quan-
tities of fat or oil and emulsifying agents were used, the types of emulsions
formed varied, depending on the emulsifier used and whether the oil was
added to the emulsifier, or vice versa.
With egg yolk all the oils and fats gave a very stable emulsion of the
oil-in-water type. With egg white as the emulsifier, oil forms an oil-in-
water emulsion. Fig. 26 shows an emulsion of corn oil and egg white.
When the oil is added gradually to the egg white, a foam as well as an
emulsion is formed. The large white spheres are air bubbles. The oil is
colored red and in the photomicrograph shows black. The illustration also
shows that the oil is adsorbed in the film or layer at the interface between
a liquid and a gas.
When a given weight of butter is added gradually to an equal weight
of egg white, an oil-in-water emulsion is formed. With the last additions
of the butter the emulsion may break. If beating is continued, a water-
in-oil emulsion may form. In melting butter the curdy part containing
the casein settles to the bottom of the container and consequently is usually
272
EMULSIONS
the last portion to be added to the egg white. It may have some effect
upon the reversal of the emulsion. Sometimes onl3^ an oil-in-water emul-
sion forms. Whether this is due to the salt or casein content of the butter
or to the temperature maintained is not known. The emulsion obtained
when egg white is added to the melted butter may be a water-in-oil or
an oil-in-water.