Following is a “Table of Analysis” of food products, from The Key to Rational Dietetics by Otto Carque. Chapter XV of that book includes these analyses and comments on them; the material is concise and applies today as much as at the time Mr. Carque published his fine book, a classic of its kind, more than three decades ago.
The amounts of organic salts in 1000 parts of water-free substance were calculated by Mr. Carque with the object of furnishing a means of comparing them on an equal basis with the respective amounts of total mineral matter contained in the solid material. Where no figures are given, no analysis is available. Very few analyses have been made to determine the contents of manganese, fluorine and iodine in foods. For this reason these elements do not appear in the tables. Some analyses of iodine in foods are given in Chapter X.
Analyses of mineral matter of different foods grown in different localities should be made frequently, in order to determine the variation of their mineral contents and the particular elements needed for improving both soil and food products. This is highly important, when we consider the fact that many plant diseases and insect pests are traceable to impoverished or wrongly fertilized soils.
The analyses presented in these tables were taken, Mr. Carque says, mostly from the following sources:
Dr. J. Koenig, Chemie der Menschlichen Nahrungs and Genussmittel (Chemistry of Human Foods and Food-Accessories).
Dr. E. Wolff, Aschen Analysen (Analyses of Mineral Matter in Foods).
Dr. Ragnar Berg, Die Nahrungs and Genussmittel, ihre Zusammensetzung and ihr Einfluss auf die Gesundheit mit besonderer Beruecksichtigung der Aschen Bestandteile (Foods, Their Comoposition and Influence Upon Health, with Special Reference to Their Contents of Mineral Matter).
Dr. Henry C. Sherman, Chemistry of Food and Nutrition.
U. S. Department of Agriculture, Bureau of Chemistry, Bulletin No. 87, Chemical Composition of Some Tropical Fruits and their Products.
Wilson Popenoe, Manual of Tropical and Subtropical Fruits. Bulletins published by Professor E. P. Forbes of the Ohio Agri-cultural Experiment Station.
Comparatively few analyses of this kind have been made in this country. As early as 1904 Mr. Carque wrote to Dr. Harvey W. Wiley, then chief of the Bureau of Chemistry, a branch of the U. S. Department of Agriculture, Washington, D. C., and this was his reply:
“I regret to say that no one in this country has undertaken a complete analysis of all the mineral constituents of foods. An analysis usually relates to the nutritive value and general composition, but does not give, as a rule, the composition of ash.
“I think it is highly desirable that the composition of ash be carefully studied and hope that some chemist will take that matter up in the near future.”
THE IMPORTANCE OF FREQUENT SOIL ANALYSES
Mistakes in Soil Fertilization
The nutritive value of fruits and vegetables depends largely on the chemical composition of the soil and the kind of fertilizers that have been applied. In buying vegetables we seldom know where and in what kind of soil they have been grown. Only soil rich in the essential mineral elements can produce sound and wholesome vegetables, while the continuous application of manures and commercial fertilizers supplies an excess of nitrogen and phosphoric acid, causing a rank and rapid growth, which misleads the inexperienced consumers. Large-sized products generally suffer from a surplus of ammonia and from lack of alkaline bases. They have no keeping qualities and easily fall prey to bacteria and fungi and quick decay.
Vast sums are annually spent for various nitrogen compounds with no other result than the production of rankness in early growth, like that produced by a hotbed. The leaves and stalks become weak because, during the brief time of their abnormal and rapid growth, they cannot absorb from the soil a sufficient amount of such sub-stances as silicic acid, iron and lime. These are the elements which give to the plant the necessary firmness and power of resistance against injurious atmospheric influences and insect pests. Insects do not propagate very well on leaves and fruits rich in lime and iron, while the stalks of plants, stimulated in their growth by an excess of nitrogen, fail to acquire the necessary stiffness and strength and are always liable to be laid by heavy wind and rain.
What has been said in the preceding chapters about mineral elements, in their relation to the rational nutrition and normal growth of the animal and human body, may to a large extent be applied to the vegetable kingdom. Plants and trees often suffer from a deficiency or excess of certain elements in the soil. These conditions naturally cause poor crops and lowered stability of the plant protoplasm, making it susceptible to rapid disintegration and the attack of fungi.