Carbonaceous Foods
While all foods contain a combination of elements, the foods described below contain a greater proportion of carbohydrates and fats, and are classed as carbonaceous.
Roots and Tubers
Of the carbohydrates, next in importance to the sugars and to the starches in their purest form (corn starch, tapioca, sago, and arrowroot), come the roots and tubers, such as potatoes, sweet potatoes, beets, parsnips, turnips and onions.
The following table shows the proportion of various foodstuffs in these vegetables:
TABLE I—ROOTS AND TUBERS
| Food Materials | Water Per Cent | Protein Per Cent | Fat Per Cent | Carbohydrates Per Cent | Ash Per Cent | Food Value per pound Calories |
| Sweet Potatoes | 69.4 | 1.5 | 0.3 | 26.2 | 2.6 | 440 |
| White Potatoes | 75.0 | 2.1 | 0.2 | 22.0 | 0.7 | 295 |
| Parsnips | 64.4 | 1.3 | 0.4 | 10.8 | 1.1 | 230 |
| Onions | 86.0 | 1.9 | 0.1 | 11.3 | 0.7 | 225 |
| Beets | 87.0 | 1.4 | 0.1 | 7.3 | 0.7 | 160 |
| Carrots | 88.2 | 1.1 | 0.4 | 8.2 | 6.0 | 210 |
| Turnips | 92.7 | 0.9 | 0.1 | 0.1 | 0.6 | 120 |
Potatoes. It will be noted from the above table that sweet potatoes have a larger percentage of carbohydrates, hence they produce more heat and energy, than any other vegetable; next to the sweet potato, the Irish potato.