| Per cent. | |
| Water | 16·5 |
| Fat | 1·5 |
| Gluten | 12·0 |
| Modified starch | 3·5 |
| Vegetable albumen | 1·0 |
| Starch granules | 64·8 |
| Ash | 0·7 |
The average of numerous analyses of American flour examined by the Department of Agriculture gave:—
| Per cent. | |
| Water | 11·67 |
| Fat | 1·25 |
| Sugar | 1·91 |
| Dextrine | 1·79 |
| Starch | 71·72 |
| Soluble albuminoids | 2·80 |
| Insoluble „ | 7·90 |
| Total „ | 10·70 |
| Ash | 0·54 |
The composition of the ash of flour from Minnesota wheat (1883), is as follows:—
| Per cent. | |
| Insoluble | 0·98 |
| Phosphoric acid | 49·63 |
| Potassa | 31·54 |
| Magnesia | 9·05 |
| Lime | 5·87 |
| Soda | 2·93 |
Analysis of Flour.
The following are the determinations generally required in the proximate analysis of flour:—
Water.—Two or three grammes of the sample are weighed in a tared platinum dish, and heated in an air bath, until constant weight is obtained. The proportion of water should not exceed 17 per cent.
Starch.—A small amount of the flour is placed in a flask, connected with an ascending Liebig’s condenser, and boiled for several hours with water slightly acidulated with sulphuric acid. Any remaining excess of acid is then neutralised with sodium hydroxide; the solution is considerably diluted, and the glucose formed, estimated by means of Fehling’s solution (see p. [111]). 100 parts of glucose represent 90 parts of starch.