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STARCH OF INDIAN CORN.
sulfuric acid (1 to 3) and extract with ether. Separate the ether layer, allow the ether to evaporate spontaneously, and take up the residue with water. If saccharin be present its presence will be indicated by the sweet taste imparted to the water. To confirm this test add from one to two grams of sodium hydroxid, and place the dish in an oil bath. Maintain the temperature of the oil at 250° C. for 20 minutes, when the saccharin will be converted into salicylic acid. After cooling and acidifying with sulfuric acid, extract in the usual way and test for salicylic acid. This test, of course, presupposes the absence of salicylic acid in the original sample. If salicylic acid is present in the original sample it must be removed before making the test for saccharin.
FIG. 27.-INDIAN CORN STARCH. X 200.-(Bureau of Chemistry.)
Starch of Indian Corn.-Maize starch has characteristics which enable it to be easily detected by the microscope. The granules of this starch are of a more uniform size than those of wheat and vary from 20 to 30 microns in diameter. Occasionally very much smaller granules occur which probably are more of the original size and which have been arrested in growth by the ripening of the grain. The granules of maize starch are more or less polyhedral in form with round angles. The only common cereal starch which they can be mistaken for is rice, but they are generally larger than the granules of rice. Under the microscope with ordinary light they give only the faintest sign of
rings but show in most cases a well developed hilum, which is at times starshaped or like an irregular cross, while at other times it has the appearance of a circular depression. The maize starch granular is a type of the angular, as the wheat is of the sphere or spheroid form. The characteristic appearance of maize starch kernels is shown in the accompanying Fig. 27. Viewed with polarized light the starch grains of Indian corn present deep, well marked crosses, which divide each grain into four distinct parts as shown in Fig. 28. It is interesting to note that the angularity of maize starch is greatly influenced by the hardness of the kernels from which the grains are taken. The hard varieties, such as popcorn, have very angular grains while those from soft varieties have a great many almost spherical forms.
Maize Flour (Corn Meal).-Formerly the maize kernel was ground between stones, bolted to remove the bran, and the maize flour or corn meal thus produced used directly as a human food. Modern milling operations have changed the method of producing maize flour so that not only is the outer bran removed but also, to a large extent, the germ itself, thus diminishing the quantity of fat in the prepared meal. This is notably true of the maize flour which is prepared for exportation. Leaving in the flour such a large quantity of fat tends to produce rancidity during shipment. To avoid any change of a deleterious nature which the flour may undergo during shipment,
COMPOSITION OF MAIZE FLOUR.
231 it is also frequently kiln-dried before being sent to foreign shores and even when intended for domestic consumption at points remote from the mill.
While this preparation of maize flour is doubtless important for transportation purposes, it impairs the palatability and nutritive value of the product. It is advisable to continue to have the maize flour prepared in the old-fashioned way and sent directly into consumption.
Method of Preparation.-One method of preparing the maize flour is as follows: The grains are broken into large pieces and dried with steam heat at a temperature of from 105° to 110° C. (22r°-239° F.). The mass while still hot passes into a mill composed of two stones which revolve rapidly in opposite directions. The smaller portions of the meal, which have been reduced to a kind of gum by the high temperature, are separated by this process from the covering or the bran of the kernel. A small mass of the starchy matter leaves the mill in the form of small noodles, which are freed from any particles of bran by sifting. In this manner a mass is obtained which is quite free from fiber and fat.
The composition of maize meal prepared by the above process is as follows:
This method of preparing maize meal is not used to any extent in this country, but is said to be commonly employed in Germany.
Composition of Maize Flour.-The color of maize flour depends upon the color of the corn from which it is produced,-it may be white or yellow. The starch granules when heated in water to 62.5° C. swell up and become deformed, except a few, usually the small ones, which resist the action of water at that temperature. The starch granules of maize flour under polarized light present a black cross, very marked and very distinct when the field is obscured. When viewed under polarized light with a selenite plate the starch grains of maize are colored red with a green cross or reciprocally, and this coloration is very brilliant.
As has already been said, the composition of Indian corn meal made by the old-fashioned method of grinding and removing only the bran is practically that of the whole grain itself.
The composition of degerminated maize meal (Indian corn flour) is shown by the following average data:
The above data show that the refined Indian corn meal has lost more than three-fourths of its fat, a large portion of its mineral matter, and also a very considerable proportion of its protein, due to the separation of the bran which is extremely rich in protein and the germ which is rich both in oil and protein. A mere glance at the data shows that this refined Indian corn meal is much less nutritious than the natural meal in so far as its content of tissue-forming bodies and its faculty to furnish heat and energy are concerned. In other words, the calories are very much lower than in the natural corn meal. This is another reason for urging our people to return to the consumption of the old-fashioned material.
The Adulteration of Indian Corn Meal.-Owing to the cheapness of Indian corn in so far as is known there is no adulteration practiced. The refined Indian corn flour itself is sometimes used as an adulteration for buckwheat flour, wheat flour, and other cereal flours, but has not itself been subjected to adulteration.
Corn Bread (Indian Corn Bread).—Corn bread is a very common diet among all classes of people in the southern states and also to a considerable extent in the north.
Owing to the lack of agglutinating powers of the nitrogenous constituents of Indian corn flour, corn bread cannot be aerated or raised, as is the case with wheat bread. It is often eaten in an unleavened state. It may be partially leavened by the usual agent, namely, yeast or a chemical baking powder. Two varieties of bread are very commonly used, namely, that made of white flour or meal and that made of yellow. There is apparently no difference in the nutritive values of these two kinds. Some consumers prefer the white loaf and some the yellow.
Composition of Indian Corn Bread.-The composition of bread depends upon whether the whole grain flour is used from which only the coarse bran has been removed by bolting or whether the decorticated and degerminated meal is used. In the first case bread is made richer in fat and protein and in the second case richer in starch. In the bread will also be found the materials used in its preparation, namely, salt, lard or other fats, milk, yeast, or baking powder residues. The best bread is made from the freshly ground flour of the whole grain from which only the outer covering, namely, the coarse bran has been removed. As offered at many of our hotels and some private houses, corn bread has been so manipulated as to lose a large part of its palatability, without any compensating improvement of its nutritive properties.
OATS (GENUS Avena).
This cereal is an important food product, being used very largely in Europe, especially in Scotland, and also very extensively in this country as human food.
The chief use of oats is for cattle food, especially for horses. It is extraordinarily rich in its nutritive constituents and, therefore, is prized highly as a food in the building and restoration of nitrogen tissues, such as the muscles. The variety in common cultivation is Avena sativa L.
Oats are grown in almost every part of the United States, but chiefly in the northern and western portions. In the southern states the crop is planted in the late autumn or early winter. In the northern states it is chiefly a spring crop, being sown early in the spring as soon as the ground is in fair condition. The oat crop is one which requires a rather abundant and well-distributed rainfall. A spring drought is very detrimental to the growth of oats, much more so than wheat or rye. It is a crop which is well suited to be grown under irrigation.
There are many varieties of oats in cultivation, but in general characteristics they all correspond to one description. The husk adheres firmly to the grain, and when threshed the grain of a common variety of oat carries the first layer of husk or chaff with it. Oats, as bought in the market, therefore, consist not only of the kernel or grain but also of this outer, chaffy envelope. The magnitude of the crop in the United States is very great, but only an inconsiderable proportion of the whole is used for human food, and this chiefly in some form of oatmeal. The statistics of the crop grown in the United States during 1906 are given in the following table:
Ratio of Kernel to Hull.-Numerous examinations of unhulled oats show that the average percentage of kernel to hull for 100 parts is as 73 to 27. In the oats grown in the western states the proportion of kernel is relatively higher and in the southern states lower.
In the analytical process if the hull or chaff is ground with the grain the proportion of fiber or crude cellulose is very considerably higher than in the class. of cereals ground without the chaff. The mean composition of unhulled kernels of oats of American growth is represented by the following table:
A study of the above data shows that the flour of unhulled oats is rich in fat, fiber, and ash. The large percentage of fiber and ash is due to a great degree