—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.[24] 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.
[24] U. S. Dept. Agr. Bureau of Chemistry, Circular No. 28, pp. 11-12.