Appearance. When starch grains are ex¬
amined under the microscope, each kind
shows a form characteristic of the plant from
which it was obtained. Starch granules are
built up in an orderly arrangement of two
different forms of starch called amyloses.
Starches from different sources are not uni¬
form, but vary from each other in the rela¬
tive amounts of these two amyloses which
they contain.
All starches tend to show concentric mark¬
ings running out from a central point called
the hilum, or the point of origin. This seems
to be the point at which the starch grain has
commenced to grow and it is plausible to
assume that the markings are in some way
connected with the laying down of the two
simple forms of starch in the grain.
The size and shape of the starch grains
seem to depend also upon the compactness
with which they have been packed in the
storage cells of the plant. Potato and arrow-
root starches have large grains shaped like
oyster shells. In these the concentric mark¬
ings show up well. The cereal starch grains
are smaller, and in most cases angular, as if
the sides had been flattened by pressure.
COMPOSITION AND NUTRITIVE
VALUE
Separated starch, like sugar, is a pure car¬
bohydrate, closely related in chemical form
to the sugars. Just as the double sugars are
built up in the plant from simple sugars, so
the starches are built up from a number of
molecules of dextrose (CeH^Oe) with the
elimination of a molecule of water (H20) for
each molecule of dextrose added. This is in¬
dicated by the formula (C6HioOs)x. This
basic unit is combined many times to make a
grain of starch. When starch is boiled with
acid, it takes up water and forms glucose,
reversing the process of starch formation in
the plant. (See page 28.) Weight for weight,
starches and sugars yield the same amount of
energy.
Cooked starches are easily digested. Raw
starch is digested more slowly and may cause
discomfort. Prehistoric man probably con¬
sumed most of his food raw; but civilized
man has accustomed his digestive tract to
cooked foods. Cooked starch now is preferred
because of the greater ease of digestion and
increased palatability of the cooked product.
STARCH COOKERY
The flavor of starch as well as its digesti¬
bility is improved by cooking. Some persons
can detect the flavor of raw starch in foods.
Starch may be cooked by either dry or moist
heat.
Dry Heat. Dry heat changes starch to sim¬
pler compounds called dextrins. These have
a sweetish taste and are soluble in water. In
concentrated solutions dextrins form a
gummy liquid known commercially as Brit¬
ish gum. This is the sweetish adhesive used
on postage stamps. Dextrins give a reddish-
brown color with iodine in contrast to the
blue color given by starch.
When bread is toasted, a portion of the
starch is changed to dextrin, flavor is devel¬
oped, and the texture is changed. By slow
toasting a large proportion of the starch may
be changed. Since dextrin is the first stage
in the digestion of starch, well-toasted bread
or zwieback is recommended for infants and
persons who for any reason do not digest
starch readily.
Page 55
Presented as published in 1935. 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
Appearance. When starch grains are ex¬ amined under the microscope, each kind shows a form characteristic of the plant from which it was obtained. Starch granules are built up in an orderly arrangement of two different forms of starch called amyloses. Starches from different sources are not uni¬ form, but vary from each other in the rela¬ tive amounts of these two amyloses which they contain.
All starches tend to show concentric mark¬ ings running out from a central point called the hilum, or the point of origin. This seems to be the point at which the starch grain has commenced to grow and it is plausible to assume that the markings are in some way connected with the laying down of the two simple forms of starch in the grain.
The size and shape of the starch grains seem to depend also upon the compactness with which they have been packed in the storage cells of the plant. Potato and arrowroot starches have large grains shaped like oyster shells. In these the concentric mark¬ ings show up well. The cereal starch grains are smaller, and in most cases angular, as if the sides had been flattened by pressure.
Separated starch, like sugar, is a pure car¬ bohydrate, closely related in chemical form to the sugars. Just as the double sugars are built up in the plant from simple sugars, so the starches are built up from a number of molecules of dextrose (C6H12O6) with the elimination of a molecule of water (H20) for each molecule of dextrose added. This is in¬ dicated by the formula (C6HioOs)x. This basic unit is combined many times to make a grain of starch. When starch is boiled with acid, it takes up water and forms glucose, reversing the process of starch formation in the plant. (See page 28.) Weight for weight, starches and sugars yield the same amount of energy.
Cooked starches are easily digested. Raw starch is digested more slowly and may cause discomfort. Prehistoric man probably con¬ sumed most of his food raw; but civilized man has accustomed his digestive tract to cooked foods. Cooked starch now is preferred because of the greater ease of digestion and increased palatability of the cooked product.
STARCH COOKERY
The flavor of starch as well as its digesti¬ bility is improved by cooking. Some persons can detect the flavor of raw starch in foods. Starch may be cooked by either dry or moist heat.
Dry Heat. Dry heat changes starch to sim¬ pler compounds called dextrins. These have a sweetish taste and are soluble in water. In concentrated solutions dextrins form a gummy liquid known commercially as Brit¬ ish gum. This is the sweetish adhesive used on postage stamps. Dextrins give a reddish-brown color with iodine in contrast to the blue color given by starch.
When bread is toasted, a portion of the starch is changed to dextrin, flavor is devel¬ oped, and the texture is changed. By slow toasting a large proportion of the starch may be changed. Since dextrin is the first stage in the digestion of starch, well-toasted bread or zwieback is recommended for infants and persons who for any reason do not digest starch readily.