The student, having familiarized himself with the chemistry of foodstuffs, is equipped to proceed with a study of food materials as they are found in the markets. Throughout these chemical tests, outlined below, the student should have before him the tabulated chemical analyses given in the body of the book.

I. Cereals

1. The Grains

Take kernels of wheat, corn, rice, oats, and rye; soak them for several hours, perhaps even boiling them for a time. Dissect these grains carefully with pen knife and dissecting needles, separating coats, germ, etc. If the facilities are at hand, make a very thin slice of the soaked grain with a razor and study the section under the microscope, making out the different coats of the grain and finding the starch grains. These latter may be stained with dilute iodin and studied under the microscope.

2. Meals And Flours

These meals and flours from the cereals may be studied chemically by making a paste and subjecting this to a test for starch, sugar, protein, and fats, tabulating results.

3. Breads

Several kinds of bread may be subjected to a similar series of experiments, tabulating results and formulating general conclusions.

II. Starches

Cornstarch, tapioca, sago, and arrowroot may be tested, not only for starch, but for sugars, proteins, and fats. These experiments will demonstrate to the student that the foods in question are practically pure starch.

III. Roots And Tubers

Potatoes (white and sweet), beets, parsnips, turnips, and onions should be subjected to tests for starch, sugar, and proteins, tabulating results.

Weight before and after drying will show water content and solids. Weight before and after burning will show organic and inorganic materials.

IV. Green Vegetables

Cabbage, spinach, vegetable marrow, tomatoes, lettuce, celery, rhubarb, watercress, cucumbers, asparagus, and brussels sprouts. Any or all of these, and perhaps other green vegetables, may be subjected to tests for starch, sugar, and protein, tabulating the results. A study of thin sections under the microscope would add to one's knowledge of the structure and of the location of the starch granules, if these are present. Weighed portions may be dried in an oven and reweighed to determine the percentage of water. The dried portion may be burned in a platinum dish. The weighed ashes will show the inorganic material. The amount of organic material may be determined by taking the difference between the dried matter and ash.

V. Fruits

1. Acid Fruits

Lemon, pineapple, cranberries, gooseberries, apples, may be tested, first, as to sugar. Litmus paper will show the presence of acid. The actual quantity of acid present would have to be determined by neutralizing it with a known strength of a solution of sodium hydrate. The more sodium hydrate required to neutralize the acid, the greater the amount of acid.

2. Sweet Fruits

Dates, figs, prunes, and raisins may be tested for sugar. The quantity of sugar present may be roughly determined by the quantity of precipitate. An accurate determination of the sugar present may be determined by a careful measurement of the amount of Fehling's solution, reduced by the sugar.

3. Bland Fruits

Pears, melons, bananas, may be tested as to starch and sugar.

All of the above-named fruits, and many others, may be tested as to amount of water and solids. The solids in turn may be tested as to the proportions of organic and inorganic materials, following the methods set forth above.

VI. Nuts

Almonds, Brazil nuts, filberts, hickory nuts, pecans, English walnuts, black walnuts, chestnuts, may be tested for starch, sugar, proteins, and fats. Those nuts in which starch is found are more wholesome and easily digested if cooked before eating. Nuts which do not have starch do not need cooking.

VII. Legumes

1. Dried Legumes

Navy beans, dried peas, dried lima beans, lentils, and peanuts. These seeds should all be soaked and perhaps boiled for some time in order to facilitate the experiments. Dissecting the soaked seeds, one may remove the skin and find the seeds separated into two seed leaves, or cotyledons, joined by a tiny stem and rootlet. A thin slice may be studied under the microscope to show the location of starch granules.

Subject the crushed legumes to tests for starch, proteins, and fat. Tabulate results.. Water content, ash, and organic substance may be determined as above outlined.

2. Fresh Legumes

Shelled green peas, string beans, shelled green beans, canned peas, canned lima beans, may be subjected to the tests for starch, sugar, and proteins, tabulating the results.

VIII. Animal Foods

Various kinds of meat, lean and fat mixed, may be subjected to tests for protein, fat, and carbohydrate. The negative test for carbohydrate emphasizes the fact that meats must be looked upon as a source for proteins and fats. Exceptions to this rule are found in liver, which shows a strong sugar test. If it could be tested immediately following the death of the animal, it would be found to contain animal starch or glycogen. This glycogen changes to sugar under the influence of a diastasic ferment very soon after death. Oysters, clams, and mussels show the presence of carbohydrates. These being represented by the seaweed in the stomach of an animal.

The proportion of water and solids and of organic and inorganic material may be determined as outlined above.