Use of Starch. — Starch, when digested, is utilized in the
body in furnishing energy expended as body heat, as work,
or stored as fat. It never builds any other tissue in the
body, hence must always be used with muscle-producing
foods, the proteins.
Method. — Starch.
Composition and Form. — Use a microscope to show
individual granules as well as position in cell. (Cut a
STARCHY FOODS 67
very thin slice of raw potato to illustrate cells containing
starch.)
Experiment 1. Com2>ositlon. — Place dry starch in test-
tube and apply heat from Bunsen burner. Note the change
in color, the odor, the moisture on sides of tube, and near
end of experiment apply lighted match to mouth of test-
tube to ignite the combustible gases driven off. Break tube
and examine its contents.
If nitrogen Avere present, the odor would have been like
burnt feathers.
Experiment 2. Action of Cold Water on Starch. — To i tea-
spoon corn starch add 2i teaspoonfuls cold water. Mix thor-
oughly. Allow it to stand till starch settles. When water
is clear, drain it off and dry the starch. Draw conclusions.
Experiment 3. Action of Boiling Water on Starch. — To
2|- teaspoonfuls boiling water in test-tube add ^ teaspoon
dry starch, without stirring. Examine the lumps and ex-
plain the condition.
Experiment 4. Action of Heat on Cold Water Mixture. —
To \ teaspoon corn starch add 2i teasponfuls cold water.
Mix thoroughly, and continue to stir while heat is applied.
Use a thermometer to note the temperature when mixture
becomes thick, when clear. What has become of starch
granules. Dilute with water. Draw conclusions.
Experiment 5. Action of Cold Water on Vegetables soaked
in them. — Wash and pare a potato, slice it, and let slices soak
in cold water for one-half hour. Examine the water. Drain
and apply heat to the white sediment in dish. It thickens.
Why?
Experiment 6. Put rice in boiling water. Note the
milky color of fluid. Let this product stand and examine
sediment. Apply heat as in Experiment 5. Are the results
similar ? (Dry the rice for future work.)
Should starchy vegetables be soaked in cold water?
68 HANDBOOK OF DOMESTIC SCIENCE
Boiling Vegetables.
Experiment 7. Wash and pare thinly two crisp potatoes.
Place them in boiling salted water. (1 tablespoon salt to
1 quart water.) Continue to boil the water till the potatoes
are soft. Remove one from the water and keep in warm
place, uncovered. Cook the second potato longer or till
gummy. Compare the dry, mealy condition of the first
with the gummy, slightly sweet condition of the second.
Give list of Starchy Foods.
Experiment 8. Home Work for Pupil. — Pare a large
potato, and grate it into a bowl of cold water. Drain off
milky water and add fresh. Save the milky water. Eepeat
this process till starch is all washed from the fibre.
Let the water stand. Drain and dry the starch. Dry
the fibre or cellulose left after washing out the starch.
Bring the results to the class.
If the period for work will not permit every experiment,
omit those on rice. If a microscope is not available, place
drawings on board, and have pupils hold thin slices of
potato to the light to see structure.
The boiled potato may be put through vegetable press,
thus making riced potatoes. The potatoes used in Experi-
ment 5 may be used in preparing escalloped potatoes. ✪ Riced Potatoes
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Use of Starch. — Starch, when digested, is utilized in the
body in furnishing energy expended as body heat, as work,
or stored as fat. It never builds any other tissue in the
body, hence must always be used with muscle-producing
foods, the proteins.
Method. — Starch.
Composition and Form. — Use a microscope to show
individual granules as well as position in cell. (Cut a
STARCHY FOODS 67
very thin slice of raw potato to illustrate cells containing
starch.)
Experiment 1. Com2>ositlon. — Place dry starch in test-
tube and apply heat from Bunsen burner. Note the change
in color, the odor, the moisture on sides of tube, and near
end of experiment apply lighted match to mouth of test-
tube to ignite the combustible gases driven off. Break tube
and examine its contents.
If nitrogen Avere present, the odor would have been like
burnt feathers.
Experiment 2. Action of Cold Water on Starch. — To i tea-
spoon corn starch add 2i teaspoonfuls cold water. Mix thor-
oughly. Allow it to stand till starch settles. When water
is clear, drain it off and dry the starch. Draw conclusions.
Experiment 3. Action of Boiling Water on Starch. — To
2|- teaspoonfuls boiling water in test-tube add ^ teaspoon
dry starch, without stirring. Examine the lumps and ex-
plain the condition.
Experiment 4. Action of Heat on Cold Water Mixture. —
To \ teaspoon corn starch add 2i teasponfuls cold water.
Mix thoroughly, and continue to stir while heat is applied.
Use a thermometer to note the temperature when mixture
becomes thick, when clear. What has become of starch
granules. Dilute with water. Draw conclusions.
Experiment 5. Action of Cold Water on Vegetables soaked
in them. — Wash and pare a potato, slice it, and let slices soak
in cold water for one-half hour. Examine the water. Drain
and apply heat to the white sediment in dish. It thickens.
Why?
Experiment 6. Put rice in boiling water. Note the
milky color of fluid. Let this product stand and examine
sediment. Apply heat as in Experiment 5. Are the results
similar ? (Dry the rice for future work.)
Should starchy vegetables be soaked in cold water?
68 HANDBOOK OF DOMESTIC SCIENCE
Boiling Vegetables.
Experiment 7. Wash and pare thinly two crisp potatoes.
Place them in boiling salted water. (1 tablespoon salt to
1 quart water.) Continue to boil the water till the potatoes
are soft. Remove one from the water and keep in warm
place, uncovered. Cook the second potato longer or till
gummy. Compare the dry, mealy condition of the first
with the gummy, slightly sweet condition of the second.
Give list of Starchy Foods.
Experiment 8. Home Work for Pupil. — Pare a large
potato, and grate it into a bowl of cold water. Drain off
milky water and add fresh. Save the milky water. Eepeat
this process till starch is all washed from the fibre.
Let the water stand. Drain and dry the starch. Dry
the fibre or cellulose left after washing out the starch.
Bring the results to the class.
If the period for work will not permit every experiment,
omit those on rice. If a microscope is not available, place
drawings on board, and have pupils hold thin slices of
potato to the light to see structure.
The boiled potato may be put through vegetable press,
thus making riced potatoes. The potatoes used in Experi-
ment 5 may be used in preparing escalloped potatoes.