When coagulated by heat
they form a cement-like structure throughout the dough. If fat or oil is
mixed with the flour particles, and water is then added, the fat coats a
portion of the flour particles and forms layers, sheets, or films between
them, giving the baked product tenderness. The factors that afifect the area
of the flour covered are (1) manipulation, (2) temperature, (3) the
ingredients used and their concentration, (4) the consistency of the fat or
oil when added and its degree of unsaturation, and (5) the concentration
of the fat.
Manipulation. The manipulative factors include creaming, the thorough-
ness with which the fat is mixed with the flour, and the manner of rolling,
kneading, etc. In products containing sugar, if the fat and sugar are creamed
so that air is incorporated, the product may be shorter or more tender.
This will depend somewhat on the proportion of fat and sugar, and whether
the maximum amount of air is incorporated. With certain proportions of
fat to sugar more air can be incorporated. The increased shortness of the
product may be attributed to the increased porosity. But creamed fat is
also more plastic and thus more easily blended with flour. In addition the
566 FATS AND OILS
sugar crystals absorb fat which may aid in distributing fat in a batter but
will probably reduce the area of the flour covered by the fat and thus tend
to reduce the shortening power of the fat. This may at least partially
explain why wafers, made by adding sugar to a standard pastry dough,
are shorter with creamed fats, and least short with oils, the order of
shortening power being nearly reversed from the order in pastry.
In pastry the fat is mixed with the flour before the water is added.
If this mixing is extensive so that the flour particles are well coated with
the fat or oil, the product is shorter than when made from the same fat
only slightly mixed with the flour. In the last instance the distribution of
the fat increases and in the first decreases the heterogeneity of the final
product. An oil or melted fat coats the flour particles more thoroughly
with short mixing than a plastic fat. Noble et al. found flour added to the
board when the dough was rolled lessened the shortening value of a modified
shortbread.
Temperature. Temperature affects the plasticity of a fat and the mobility
of a melted fat or of an oil. At lower temperatures the plasticity of fats
such as butter is not great. They spread less readily and the area of flour
and other particles covered is less with the same extent of mixing than at
higher temperatures. But at higher temperatures the surface area covered
by a melted fat may decrease because of the increased tendency to form an
oil-in-water emulsion, particularly in thin batters. In addition, at tempera-
tures at which the fat is melted or very soft the gluten absorbs w^ater
rapidly and becomes developed rapidly. This development of the gluten
may offset increased shortening power owing to the soft fat coating a
greater flour surface.
Page 451
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When coagulated by heat
they form a cement-like structure throughout the dough. If fat or oil is
mixed with the flour particles, and water is then added, the fat coats a
portion of the flour particles and forms layers, sheets, or films between
them, giving the baked product tenderness. The factors that afifect the area
of the flour covered are (1) manipulation, (2) temperature, (3) the
ingredients used and their concentration, (4) the consistency of the fat or
oil when added and its degree of unsaturation, and (5) the concentration
of the fat.
Manipulation. The manipulative factors include creaming, the thorough-
ness with which the fat is mixed with the flour, and the manner of rolling,
kneading, etc. In products containing sugar, if the fat and sugar are creamed
so that air is incorporated, the product may be shorter or more tender.
This will depend somewhat on the proportion of fat and sugar, and whether
the maximum amount of air is incorporated. With certain proportions of
fat to sugar more air can be incorporated. The increased shortness of the
product may be attributed to the increased porosity. But creamed fat is
also more plastic and thus more easily blended with flour. In addition the
566 FATS AND OILS
sugar crystals absorb fat which may aid in distributing fat in a batter but
will probably reduce the area of the flour covered by the fat and thus tend
to reduce the shortening power of the fat. This may at least partially
explain why wafers, made by adding sugar to a standard pastry dough,
are shorter with creamed fats, and least short with oils, the order of
shortening power being nearly reversed from the order in pastry.
In pastry the fat is mixed with the flour before the water is added.
If this mixing is extensive so that the flour particles are well coated with
the fat or oil, the product is shorter than when made from the same fat
only slightly mixed with the flour. In the last instance the distribution of
the fat increases and in the first decreases the heterogeneity of the final
product. An oil or melted fat coats the flour particles more thoroughly
with short mixing than a plastic fat. Noble et al. found flour added to the
board when the dough was rolled lessened the shortening value of a modified
shortbread.
Temperature. Temperature affects the plasticity of a fat and the mobility
of a melted fat or of an oil. At lower temperatures the plasticity of fats
such as butter is not great. They spread less readily and the area of flour
and other particles covered is less with the same extent of mixing than at
higher temperatures. But at higher temperatures the surface area covered
by a melted fat may decrease because of the increased tendency to form an
oil-in-water emulsion, particularly in thin batters. In addition, at tempera-
tures at which the fat is melted or very soft the gluten absorbs w^ater
rapidly and becomes developed rapidly. This development of the gluten
may offset increased shortening power owing to the soft fat coating a
greater flour surface.