Sweet Corn

This is a variety of maize which develops a high sugar content and is eaten while the starch is yet soft, in other words, in an unripe state. It is a food product of immense importance in the United States, although almost unknown in Europe. The content of sugar varies from 5 to 8 percent in the fresh, soft kernel. The sugar which is present in the kernel rapidly disappears after the husking or removal from the stalk. In order to secure the maximum sweetness the corn should be cooked and eaten as soon as possible after removal from the stalk. Where it is not possible to do this it should be placed in cold storage after removal from the stalk and remain unhusked until it is ready for cooking. Green corn is universally eaten hot. It is usually cooked by boiling in water, although it may also be roasted before the fire. It has a high food value, and the composition of the grains of fresh, soft, green corn is shown in the following table:

Composition of Fresh Green Indian Corn:

Moisture, 73.00 percent

Starch, 13.50 „

Sugars, 6.00 „

Protein, 5.00 „

Crude fiber, 1.20 „

Ash, .70 „

Fat, .60 „

Maize Proteins.

—The proteins of maize are composed principally of two zeins. The two forms are differentiated by their behavior toward alcohol. The first form constitutes the zein soluble in alcohol and the second the zein insoluble in alcohol. There are two other proteins in maize existing in small quantities which have been named myosin and vitellin, respectively. There is also a third unnamed variety and small quantities of albumin.

Variation in Maize, under Different Climatic Conditions.

—It is possible that most of the varieties and subvarieties of maize are simply the existing standard varieties modified by changing environments. There are certain conditions of climate, soil, and distribution of rainfall which tend to produce a large, starchy, soft grain, while other conditions tend to produce a small, hard grain richer in protein. The variations of importance are those of the carbohydrates and the protein, which are complementary, since as the protein rises the carbohydrates fall in relative proportion. There is also a marked variation in the carbohydrates, due to variety and climatic conditions combined. It is, for instance, the increase of the sugar at the expense of the starch that produces the body known as sweet maize eaten in the green state, as already described. Even in the sweet variety the relative proportion of sugar varies in different localities and under different conditions of growth.

Early Varieties.

—There are certain varieties of maize which are of especial value on account of their early maturation. This is a property extremely valuable in the sweet variety of maize or that eaten in the green state, since it is important to get these varieties into the market as early as possible and to continue them as long as possible. This is secured by planting the early variety at as early date as possible and planting later maturing varieties at intervals thereafter. By the selection of varieties of different periods of maturing it is possible in the climate of Washington to offer green corn from neighboring fields on the market from July until the advent of a killing frost which is usually the last of October or first of November. This gives a period of nearly four months during which the green corn may be delivered to the local market. Further south the period of supply is longer.

Canned Corn.

—Immense quantities of green corn are grown for the purpose of canning in order to supply the market during the closed season. The canning industry for green corn is located chiefly in the north. In the eastern states the industry is of great importance, from Maryland to Maine. The northern-grown corns are often preferred as they are supposed to be sweeter and more palatable. In the central western states, northern Indiana, Michigan, Wisconsin, northern Illinois, and Iowa are the principal centers of the canning industry, although it is practised to a greater or less extent in almost all parts of the country.

Adulterations of Canned Corn.

—Unfortunately in the canning process of corn additions have been made to the product which are of an objectionable nature. Chief among these is the use of bleaching agents such as sulfur in the form of burnt sulfur or of sulfite or bisulfite of soda or potash. These bleaching agents impart to the corn a white color which some consumers prefer, but at the expense of introducing a substance which must be regarded as deleterious to health. Still more objectionable is the practice of using saccharin instead of sugar as a sweetening agent. Saccharin is a coal tar product which has an intense, sweet taste, very persistent, and when used alone becomes disagreeable. A very small quantity of it is sufficient to impart a very sweet taste to the canned corn at a much less expense than could be secured by using the pure sugar. This form of adulteration is extremely reprehensible both because it deceives the consumer and adds a substance which by most hygienists is regarded as prejudicial to health. The bleaching agent and the artificial sweetener are wholly unnecessary. The manufacturers of sweet corn are expected to use the best and freshest and sweetest materials and cannot be excused for tampering with them in any way which either produces deception or injury to health.

Sugar added to make an ordinary corn taste like sweet corn is to be regarded as an adulteration unless its use is noted on the label.

Maize starch is also often added to sweet corn at the time of canning and this practice can only be regarded as an adulteration.

Detection of Adulterations in Sweet Corn.—Test for Sulfurous Acid.

—To about 25 grams of the sample (with the addition of water, if necessary) placed in a 200-c.c. Erlenmeyer flask, add some pure zinc and several cubic centimeters of hydrochloric acid. In the presence of sulfites, hydrogen sulfid will be generated and may be tested for with lead paper. Traces of metallic sulfids are occasionally present in vegetables, and by the above test will indicate sulfites. Hence positive results obtained by this method should be verified by the distillation method. It is always advisable to make the quantitative determination of sulfites, owing to the danger that the test may be due to traces of sulfids. A trace is not to be considered sufficient as indicating either a bleaching agent or a preservative.

Detection of Saccharin.

—Add from 25 to 40 c.c. of water to about 20 grams of the sample; macerate and strain through muslin; acidify with 2 c.c. of 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.

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 star-shaped 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, 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. (221°-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:

Moisture, 9.70 percent

Protein, 12.68 „

Ether extract, 1.19 „

Ash, .60 „

Fiber, .35 „

Starch, sugar, and dextrin, 71.48 „

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:

Moisture, 12.57 percent

Protein, 7.13 „

Ether extract, 1.33 „

Ash, .61 „

Fiber, .87 „

Starch and sugar, 78.36 „

Calories calculated on the moist meal, 3,837

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.