Mix half a tablespoon of cornstarch with quarter of a cup of cold water, and cook, stirring and adding measured amounts of water until you obtain the same consistency as a medium white sauce. What is the comparative thickening power of flour and cornstarch?
B. Cornstarch Mold.
Make a cornstarch mold, using a cup of milk, one tablespoon of sugar, a saltspoon of salt, and as much cornstarch as would give the consistency of the thick white sauce used in the last lesson. How will you combine the ingredients? Cook five minutes over the fire, stirring constantly; then cook covered, over water, until the "raw" taste has disappeared. This will take at least fifteen minutes.1 Remove from the fire, add a few drops of vanilla and pour into a wet mold, and let stand until cold. Serve with chocolate sauce.
Melt a quarter of a square of chocolate with a quarter of a teaspoon of butter. Add three tablespoons of water, a half cup of sugar and a few grains of salt. Boil until moderately thick; cool, and flavor with a few drops of vanilla.
1 In cooking so small a quantity so long a time, it may be necessary to allow for the increased loss by evaporation.
C. Prepare Macaroni and Tomato Sauce.
Boil until tender a quarter of a cup of macaroni broken into inch pieces in a pint of boiling water with half a teaspoon of salt. Drain and pour some cold water over it to prevent the pieces from sticking together. Reheat in an equal amount of tomato sauce. Make this as you would white sauce, but use the juice from canned tomato for the liquid. Since macaroni is starchy, use a proportion of flour that will make a sauce between thin and medium.
The manufacture of cornstarch is interesting because so many other products are made at the same time. The outline of the process is as follows.
After the corn is cleaned, it is soaked or steeped in warm water for a couple of days. In order to prevent its spoiling, a little sulphurous acid is added. When the corn is sufficiently swollen, it is ground coarsely so as to break up the kernel without breaking the germ. The germ is so rich in both protein and fat that it is most easily taken care of by itself. All that is necessary to separate it after the grinding is to run the ground mass into separators, when at a certain density of the liquid the germ, light on account of its oil content, floats on top of the water, while the ground hulls and starch settle and are drawn off from the bottom. The next problem is the separation of the starch from the hulls. It is necessary to grind the mass up much more finely than before, then the semi-liquid is passed over sieves of bolting cloth with a 200 mesh, which is shaken mechanically so that the particles of the hull are sifted out, the starch itself passing through. The hulls are separated, re-ground, and re-sifted, and sprayed with water during the process, in order to get out all the starch possible. The starch and water that goes through the sieve, however, is still mixed with protein. This liquor, at just the right density, is passed over long tanks with slightly inclined bottoms. As it flows, the starch settles and rolls along the inclined surface, thus washing itself.
The water containing the protein is usually mixed with the hulls and the dried product is used for feed for cattle. The separated germ is pressed to extract some of the oil. Corn oil is used as food only to a small extent, but it is used for making soap and in other industrial processes. The germ with the oil partly expressed is mostly exported to Europe as oil-cake, and is used for feeding stock.
After all the processes the starch has gone through, it is still crude. It may, at this stage, be used to make corn syrup and glucose, but otherwise it must be still further refined. Too much protein remains in it, so that it is further washed, sometimes with water alone, sometimes with dilute alkali. Often the plant which separates all the direct products of corn also manufactures dextrine as well as corn syrup and glucose.
Cornstarch is less difficult to mix with liquids than is flour, because it does not contain the gluten which flour does. When hot water is poured over starch, it gelatinizes the starch with which it comes into contact. The starchy grains form a mass which is impervious to water and so prevents the water reaching all of the starch grains. This can be prevented by mixing some other substance with the starch before pouring on the water, because the other substance separates the grains and gives them room to swell without sticking together. As raw starch is both less digestible and much less palatable than cooked, prevention of lumping is important.
In spite of all the purifications cornstarch has undergone in its manufacture it has a characteristic flavor which everyone readily recognizes and which must be due to some other substance mixed with the starch. Only after long cooking does this flavor disappear.
1. Give two reasons why, in making the pudding, the cornstarch is covered during the long cooking?
2. Why does cornstarch require so much longer cooking than flour?
3. If you were to make a large amount of cornstarch pudding why would you not mix the cornstarch with all of the cold milk? How would you proceed?
4. What ways can you think of to vary cornstarch pudding, besides serving it with different sauces? Consult cook books.
5. How do macaroni, spaghetti, and vermicelli differ? What do the names mean?
6. Study the cost of various macaronis to be found in your markets. Do cost and quality correspond?
7. Consult cook books and make a list of ways in which macaroni may be served.
8. How does a sauce thickened with cornstarch differ in appearance from one thickened with flour?
9. Since sauces are not cooked a long time, would you choose cornstarch to thicken a sauce which was not highly flavored? Why?
10. How does laundry starch differ from the cornstarch used for cooking?
11. Why is laundry starch in Europe manufactured from potatoes and not from corn?