A substance like acetic acid, containing a short hydrocarbon chain and a
polar group, is completely miscible with water, for the (COOH) group is
attracted to the water so strongly that the hydrocarbon chain is also
dragged into the water. When two (CH3) groups are attached to the
(COOH) group, the solubility is lessened, and with increasing length of
the hydrocarbon chain solubility in water progressively decreases. Thus the
possession of a polar group confers upon the substance a certain solubility
in water, and the possession of a non-polar group may confer upon it a
18 RELATION OF COOKERY TO COLLOID CHEMISTRY
greater solubility in some other solvent. Orientation occurs at the interface
of two liquids, such as emulsions. Polar groups are those containing oxygen,
nitrogen, sulfur, or iodine. Thus substances containing (COOH),
(CHO), or (NH2) groups, or double bonds, contain polar groups. Polar-
ity is based upon the concept that some parts of a molecule may have
gained w^hile other parts may have lost one or more electrons. This results
in differences in charges at a small distance apart. The polar groups or
polar substances are reactive; the non-polar groups or substances are more
inert.
Cohesion. Cohesion refers to the property of a substance whereby
the particles of a body are united throughout the mass. The particles as a
unit resist being torn apart.
Adhesion. Adhesion refers to the attraction whereby the surface of
a substance sticks to the adjacent surface of another substance. Drops of
water adhere to glass, and the dough adheres to the sides of the container
in which it is placed. Pans for sponge and angel cakes are not greased, so
that the adhesion of the cake mixture to the sides of the pan will aid
expansion of the cake.
Coagulation of Proteins
The term denaturation is used more frequently than coagulation by
scientific investigators at the present time to denote certain changes in
proteins. Definite characteristics of the proteins are changed when they
are coagulated, among which is loss of solubility in water and dilute salt
solutions. In some instances and under certain conditions the coagulation
process may be reversible.
Manner in which denaturation may be brought about. Coagula-
tion of proteins may be brought about by a variety of processes. In cookery
one of the principal means of coagulation is heat. But in addition to heat
the action of acids, alkalies, salts, alcohol, mechanical agitation, radiation,
and ultra-sonic vibrations may denature the protein and convert it from a
soluble into an insoluble form.
Page 18
Presented as published in 1932. Historical recipes may not meet modern food-safety standards. Cook from the modern interpretation, not the original instructions.
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A substance like acetic acid, containing a short hydrocarbon chain and a
polar group, is completely miscible with water, for the (COOH) group is
attracted to the water so strongly that the hydrocarbon chain is also
dragged into the water. When two (CH3) groups are attached to the
(COOH) group, the solubility is lessened, and with increasing length of
the hydrocarbon chain solubility in water progressively decreases. Thus the
possession of a polar group confers upon the substance a certain solubility
in water, and the possession of a non-polar group may confer upon it a
18 RELATION OF COOKERY TO COLLOID CHEMISTRY
greater solubility in some other solvent. Orientation occurs at the interface
of two liquids, such as emulsions. Polar groups are those containing oxygen,
nitrogen, sulfur, or iodine. Thus substances containing (COOH),
(CHO), or (NH2) groups, or double bonds, contain polar groups. Polar-
ity is based upon the concept that some parts of a molecule may have
gained w^hile other parts may have lost one or more electrons. This results
in differences in charges at a small distance apart. The polar groups or
polar substances are reactive; the non-polar groups or substances are more
inert.
Cohesion. Cohesion refers to the property of a substance whereby
the particles of a body are united throughout the mass. The particles as a
unit resist being torn apart.
Adhesion. Adhesion refers to the attraction whereby the surface of
a substance sticks to the adjacent surface of another substance. Drops of
water adhere to glass, and the dough adheres to the sides of the container
in which it is placed. Pans for sponge and angel cakes are not greased, so
that the adhesion of the cake mixture to the sides of the pan will aid
expansion of the cake.
Coagulation of Proteins
The term denaturation is used more frequently than coagulation by
scientific investigators at the present time to denote certain changes in
proteins. Definite characteristics of the proteins are changed when they
are coagulated, among which is loss of solubility in water and dilute salt
solutions. In some instances and under certain conditions the coagulation
process may be reversible.
Manner in which denaturation may be brought about. Coagula-
tion of proteins may be brought about by a variety of processes. In cookery
one of the principal means of coagulation is heat. But in addition to heat
the action of acids, alkalies, salts, alcohol, mechanical agitation, radiation,
and ultra-sonic vibrations may denature the protein and convert it from a
soluble into an insoluble form.