NOTE.--While cooking Blanc Mange, note the number of minutes that is required to thicken the mixture and the length of time of cooking given in the recipe. Why is it necessary to cook the mixture for so long a time after it thickens? (See _Cereals_.)
CHOCOLATE CORN-STARCH PUDDING
Proceed as for Blanc Mange, using 3/8 cupful of sugar instead of 1/4 cupful. Cut into pieces 1 square (_i.e._ 1 ounce) of Baker"s chocolate. Add to it 1/4 cupful of boiling water. Stir and heat until smooth and thoroughly blended. Add this to the corn-starch mixture just before taking from the fire. Add 1/2 teaspoonful of vanilla. Mold and serve as Blanc Mange.
Note that the quant.i.ty of sugar is increased when chocolate is added to the corn-starch mixture. Chocolate mixtures require considerable sugar to make them tasty.
3 tablespoonfuls of cocoa may be subst.i.tuted for the chocolate. When this is done, mix the cocoa with the corn-starch and sugar and add no water to it. Proceed as in making plain Blanc Mange.
QUESTIONS
Name three substances that can be used to prevent the lumping of powdered cereals used for thickening.
Give the reason for mixing the sugar, corn-starch, and hot milk of Blanc Mange as directed.
For how long a time after placing in the double boiler is it necessary to stir the corn-starch, sugar, and hot milk mixture?
Milk, especially a milk and starchy mixture, scorches readily (see _Scalding Milk_). From this explain why Blanc Mange is cooked entirely over boiling water, and not over the flame and then in a double boiler, as cereals.
Why is the flavoring not added while the mixture is cooking (see _Flavoring Extracts_)?
What is the price per package of corn-starch?
How much does a package of corn-starch weigh and measure?
Which material--flour or corn-starch--is the cheaper to use for thickening?
How many persons does the quant.i.ty of Blanc Mange above serve?
LESSON XXV
TOAST: DIGESTION OF STARCH
EXPERIMENT 26: CHANGE OF STARCH INTO DEXTRIN.--Place a teaspoonful of flour in a frying pan and heat slowly until it becomes _very dark brown_ and _uniform_ in color. Put a little of the browned flour into a test tube, add water, then shake. Add a few drops of iodine. What indicates the presence of starch? Is starch present?
The starch has been changed to dextrin. Dextrin gives a purple (reddish blue) color when treated with iodine.
EXPERIMENT 27: THE SOLUBILITY OF DEXTRIN.--Pour the remainder of the browned flour from Experiment 26 into a test tube. Add water and shake.
Pour through filter paper [Footnote 26: Liquids pa.s.s through filter paper, but solids do not. Hence if a mixture of solid and liquid is poured upon filter paper, the liquid pa.s.ses through, but the solid remains on the paper.] into another test tube (see Figure 30). Notice the color of the liquid that has been filtered. Add a few drops of iodine to the filtered liquid. Is dextrin present? Is dextrin soluble in water? [Ill.u.s.tration: Figure 30.--Method of Folding Filter Paper.]
From these experiments, we find that dry heat has changed insoluble starch into a soluble substance called _dextrin_. Dextrin is found in small amounts in the crust of bread and in toast.
DIGESTION OF STARCH.--It was found in a previous lesson (Lesson XVI) that sugar is entirely soluble in water, and since digestion and solution are closely related, the digestion of some sugar is simple. Starch was found to be insoluble in cold water and only semi-soluble in hot water. In the process of digestion it would seem that some change must take place in the starch to make it soluble. Such a change _does_ take place; starch is changed into a soluble carbohydrate or a sugar before it is digested.
Substances called _enzymes_ which are in the saliva of the mouth [Footnote 27: Ptyalin and amylopsin are the ferments found in the mouth and intestines, respectively.] and in the digestive juices of the intestines [Footnote 28: Ptyalin and amylopsin are the ferments found in the mouth and intestines, respectively.] cause this change. To show that this change takes place to some extent in the mouth, try the following experiments:
EXPERIMENT 28: STARCH IN CRACKER.--Test a bit of cracker with iodine for starch. What indicates the presence of starch? Does the cracker contain starch?
EXPERIMENT 29: ACTION OF SALIVA UPON STARCH.--Thoroughly chew a bit of cracker. As you chew the cracker, note that it becomes sweeter in flavor.
Remove from the mouth, and place upon a piece of paper. Test it with iodine. A purple (reddish blue) color indicates a soluble carbohydrate (see Experiment 27). What substance does the masticated cracker contain?
Explain the change that has taken place in the cracker by mastication.
TOAST.--Bread is properly toasted when it is dried out thoroughly and then browned on the outside. Both the crumb and the crust of the toast are thus made crisp. Crisp toast crumbles during mastication.
Fresh bread contains much moisture. When it is toasted quickly, the moisture is inclosed in the interior of the slice and the resulting toast is very soft. This kind of toast is almost as difficult to digest as fresh bread. Instead of toast breaking into bits during digestion, it remains in a solid ma.s.s and is digested with difficulty.
Give at least two practical methods of toasting bread to produce the desired kind of toast.
CREAM TOAST
1 1/2 tablespoonfuls b.u.t.ter or subst.i.tute 1/2 teaspoonful salt 2 tablespoonfuls flour 2 cupfuls milk or cream 6 to 8 slices of toast
Heat the fat; when it bubbles, add the flour and salt, mixing thoroughly.
Add a small portion of the milk. Heat and stir continually until it thickens. Add another portion of the milk and proceed as before. Continue until all the milk has been added. The sauce is sufficiently cooked when it reaches the boiling point after the last quant.i.ty of milk has been added. Pour this sauce over dry or moist toast.
_Moist toast_ is prepared by dipping dry toast quickly into hot, salted water or hot milk. If the crust has not been cut from bread for toasting, only the outer edges of the toast may be moistened.
The flavor of b.u.t.ter in Cream Toast is pleasing. To secure some b.u.t.ter flavor and at the same time economize, a combination of b.u.t.ter and a mild flavored fat or oil may be used.
QUESTIONS
Give the reason for mixing flour and fat as directed in White Sauce (see Experiment 25).
What is the proportion of fat and flour? What is the proportion of flour and liquid? Using this proportion, how much flour should be used for one cupful of liquid?
What is the use of flour in White Sauce?
Note the consistency of the sauce, and keep it in mind as a standard of comparison for the thickness of other sauces.
What should be the condition of the crumb of toast to be most quickly digested? Give reasons for your answer.
LESSON XXVI
ROOT VEGETABLES (A)
Plant Roots.--Plants used for food have their stored-up food largely in the form of starch and to some extent in the form of sugar. The parts of the plant underneath the ground as well as the seeds serve as a storehouse for the plant. All roots and tubers contain carbohydrates, although not in so large a proportion as cereals. Those most commonly used as foods are potatoes, tapioca, parsnips, carrots, beets, and turnips. Potatoes and tapioca contain the most starch in this group. Parsnips, carrots, and beets contain a little starch and much sugar. Turnips contain much cellulose. Carrots, parsnips, and beets are also rich in cellulose.
All root vegetables as well as leaf and stem vegetables contain ash.
Comparison of Vegetables Cooked with or without the Skins, and in Water or in Steam [Footnote 29: NOTE TO THE TEACHER.--This lesson can be conducted most expeditiously by dividing the cla.s.s into groups of six and having each group clean, prepare, and cook in water and in steam, potatoes and carrots as directed above.]--Clean, prepare, and cook in water pared and unpared potatoes, sc.r.a.ped and unsc.r.a.ped carrots, and cook in steam pared potatoes and sc.r.a.ped carrots.