THE RELATION OF CHEESE TO MILK.—To show the relation of cheese to milk, and to understand the manufacture of cheese, try the following:

EXPERIMENT 47: EFFECT OF RENNET ON MILK.—Put a small quantity of milk in a test tube and heat the milk a very little, taking care not to boil it. Add to it 1/4 teaspoonful liquid rennet, or 1/8 junket tablet, and set aside. After a few minutes examine the milk. How has the rennet changed the milk? What substance in the milk has been clotted by the rennet (see Lesson XLVI)?

EXPERIMENT 48: SEPARATION OF CURD AND WHEY—Again heat the contents of the test tube of Experiment 47, turn the mixture into a cheese-cloth, and press the cloth until the mixture is dry. Examine the material left in the cloth. How does it differ from ordinary cheese in color and texture? In cheese making what names are given to the solids and liquids of clotted milk?

Cheese is prepared for the market in a way somewhat similar to that shown in Experiments 47 and 48, except that it is colored, salted, pressed into shape, and allowed to ripen. While ripening, changes take place in the ingredients of cheese which develop characteristic flavors and make the cheese firm.

There are two general classes of cheese,—hard cheese and soft cheese. A hard cheese commonly known as "American Cream Cheese" is generally used in this country.

ACTION OF RENNIN IN DIGESTING MILK.—The rennet or junket used to clot the casein of the milk is obtained from the digestive juices of the stomach of a calf. An enzyme called rennin exists in the gastric juice of the human stomach also. When milk is digested, it is first clotted by the enzyme in the stomach.

EXPERIMENT 49: EFFECT OF ACID ON MILK.—Add a few drops of vinegar to warm milk in a test tube. What is the result? What substance in the milk has been curdled by the acid?

To what substance in milk is its sweet taste due? Into what has this substance changed when milk sours? What causes the change in this material (see Care of Milk)? Knowing the effect of acid on milk, explain the clotted condition of sour milk.

JUNKET "CUSTARD"

1 quart milk 1/4 cupful sugar 1 teaspoonful vanilla 1 tablespoonful liquid rennet or 1 junket tablet Powdered cinnamon or nutmeg

Heat the milk in a double boiler until it is lukewarm only; do not heat it to scalding temperature. Test milk for lukewarm, i.e. body temperature, by letting a drop fall on the wrist. If the milk "feels like the wrist"—neither warmer nor colder—it is lukewarm in temperature. If a junket tablet is used, crush it. Add the sugar, vanilla, and rennet or junket, and stir until dissolved. Pour into a glass dish and stand in a warm place until it thickens. Then set the Junket "Custard" in a cool place. When cold, sprinkle with a little cinnamon or nutmeg, and serve with cream.

COTTAGE CHEESE

1 quart thick sour milk 1/4 teaspoonful salt Cream, top milk, or butter

Pour at least 2 quarts of boiling water into the sour milk. Allow the mixture to stand until the curd separates from the whey. Strain the mixture in a cloth, pressing the cloth until the curd is dry, or allow it to drip for several hours or overnight. Put the curd in a bowl, add salt and a little cream, top milk, or melted butter, and mix thoroughly. Serve lightly heaped, or molded into balls.

QUESTIONS

Why should junket tablets be crushed before adding to the milk (see
Experiment 12)?

In what way is the preparation of milk for Junket "Custard" like the digestion of milk in the stomach?

Tell why Junket "Custard" is quickly digested.

How much Cottage Cheese is obtained from 1 quart of milk?

Explain the use of boiling water in preparing Cottage Cheese from sour milk.

What is the price per pint of Cottage Cheese prepared at home?

What is the price per pint of Cottage Cheese obtained at market?