Experiments

Potato

62. - Prepare two very thin slices of white potato, one lengthwise and one across.

Hold against a strong light.

Observe markings and lines. What are they?

Make a drawing.

See Sherman's Food Products, pages 320-321, 322.

63. - Do the same with carrot, turnip, and onion. Compare and state conclusions.

64. - Wash, pare, and grate into a bowl a good-sized white potato. Make a microscopic examination of a particle of the pulp in a drop of water, before and after treatment with a drop of dilute iodine solution. See page 13.

VEGETABLES AND VEGETABLE SOUPS 6I

65. - Pour pulp and fluid from Expt. 64 into a wet cheesecloth over a bowl of cold water.

Draw the cloth together and knead the mass in the water.

To what is the milky color of the water due?

Test a little of the water with iodine.

Boil a little.

What changes do you observe? Explain.

66. - Change the water and continue washing the pulp from Expts. 64 and 65 until the water is only slightly milky or clear. Save each water.

Open cheesecloth and examine content. What does this explain as to the structure of the potato ? What does this explain as to the cooking of potato and other starchy vegetables ?

67. - Observe the water and starch which has been standing. Decant off the water and turn sediment on to a filter paper to dry. Note the clear white color of the sediment. Note the brown color of liquid. To what is this due? (See experiments with Apple.)

68. - Add fresh cold water to a portion of the sediment obtained in Expt. 67; stir until particles are all suspended. Dip in a piece of white muslin and iron while still wet. When have you observed this same result ?

69. - Add freshly boiling water to the sediment in one bowl. Stir the mixture constantly.

How does this compare with Expt. 68?

Dip a piece of muslin in, allow it to dry, sprinkle, and iron.

70. - Repeat Expts. 68 and 69, using carrot and turnip. Compare and state conclusions.

Dextrinized Starch

71. - a. Dextrinize one tbsp. flour by heating the flour in a dry utensil.

b. Test with iodine. (See page 13.) c. Add water to make a solution.

d. Does the color turn?

e. Why not ?

f. Does the dextrin appear to be more or less soluble than flour or starch in cold water ?

g. Explain your answer.

72. - a. Thicken 1/2 c. cold water with 1 tbsp. flour.

b. Thicken 1/2 c. cold water with 1 tbsp. dextrinized flour (boil each).

c. Which mixture is thickest ? Why ?

Starchy Vegetables

Vegetables may be prepared for cooking processes by peeling or scraping. Peeling is more often done carelessly than carefully. Have ready the following vegetables: white potato sweet potato carrot turnip parsnip

73. - Wash, scrub with a brush, and weigh each vegetable. Estimate the waste in the preparation of each vegetable by the following methods: a. scraping b. peeling carefully c. peeling in the usual manner Which method is the more economical?