Classification of Foods and their General Uses in the Body:

A. Organic Foods. 1. Carbohydrates.

Composed of carbon, hydrogen, and oxygen. Examples. - 1. Starch in cereals, etc.

2. Sugar.

3. Cellulose.

Uses In Body

1. To supply heat and energy.

2. To form fat.

2. Fats.

Composed of carbon, hydrogen, and oxygen. Examples. - 1. Fat of meats.

2. Cream.

3. Butter.

4. Olive oil, etc.

Uses In Body

1. To supply heat and energy.

2. To form fat.

3. Protein.

Composed of carbon, hydrogen, oxygen, nitrogen, sulphur, and sometimes phosphorus. Examples. - 1. Albumen of egg.

2. Casein of milk.

3. Fibrin of meat.

4. Gluten of wheat.

5. Legumen of peas and beans, etc. Uses in body. - 1. To form tissue.

2. To supply heat and energy.

3. To form fat. 18

B. Inorganic Foods.

1. Water.

Composed of hydrogen and oxygen, H20.

Uses In Body

1. Forms two-thirds of body weight.

2. Carrier of nutritive material and of waste products.

2. Mineral Matter.

Examples

1. Sodium chloride.

2. Phosphate of lime.

3. Compounds of potassium, iron, magnesium, etc. Uses in body. - 1. Aid in forming bone, teeth, etc.

2. Assist in digestion.

3. Necessary for tissues, blood, etc.

C. Food Adjuncts and Accessories.

1. Condiments and Spices.

Examples

1. Mustard.

2. Pepper.

3. Spices.

Uses In Body

1. Stimulate the appetite.

2. Increase flow of digestive fluids.

2. Vegetable Acids.

Examples

1. Citric acid in lemons and oranges.

2. Malic acid in apples.

3. Oxalic acid in rhubarb.

4. Tartaric acid in grapes.

3. Caffeine in tea and coffee. Theobromine in cocoa.

Carbohydrates

A carbohydrate is a compound composed of carbon, hydrogen, and oxygen. Hydrogen and oxygen are always present in the same proportion as they are in water - 2: 1 (H20).

Chemical Formula:

The carbohydrates include starches, sugars, and plant fibers, or cellulose.

Carbohydrates are found

1. In plants as starches, sugars, and cellulose.

2. In milk as lactose or milk sugar.

3. In the liver of animals as glycogen or animal starch.

4. In body tissues as inosite or muscle sugar.

Starch is formed by the chlorophyll of the plant cell, under the action of the sun's rays, from the carbon dioxide of the air and the water drawn from the soil. The process is a complex one, but the net result may be shown by the following equation: carbon dioxide + water = starch + oxygen 6 C02 +5 H20 = C6H10O5 + 6 02 or Glucose

6 C02 + 6 H20 = C6H1206 + 6 02

Starch

Starch is the most abundantly distributed in nature of any of the carbohydrates, for it is the chief form in which plants store their carbohydrate. It is found in fruits, seeds, roots, tubers, bulbs, stems, and leaves of various plants. In the United States the starch of commerce is obtained chiefly from corn.

Starch exists in the form of minute granules which are formed in the plant during its growth. The granules are composed of alternate layers of starch and cellulose, those of different plants having characteristic shapes which can be recognized by examination with a microscope. Owing to its wide distribution, and to the fact that it may be easily stored because it does not decompose readily, starch is the cheapest form of food and is often used to excess in the diet.

Structure Of The Starch Granule

Examine under the microscope and make drawings of starch granules from corn, potato, wheat.

Identification Test For Starch

Mix a little starch and cold water, boil, and cool. Add a drop of iodine. The blue color which results is characteristic of starch. With raw starch, iodine gives a purple color.

Experiment 15

Test various foods with iodine to ascertain whether they contain starch. Tabulate results.