In the dry substance:
| Protein, | 10.18 | percent |
| Ether extract, | 9.33 | „ |
| Fiber, | .53 | „ |
| Ash, | 1.70 | „ |
| Salt, | 1.08 | „ |
| Starch and sugar, | 78.79 | „ |
| Calories, | 4,755 |
The above data show that biscuits vary in composition from bread chiefly in their content of moisture and fat or oil. The moisture, as is noted, is very low, while the quantity of fat which the biscuit contains is from 8 to 10 times as great as that contained in flour from which they are made. The salt content and the mineral ingredients of the biscuit are often higher than in bread or flour. Inasmuch as a large quantity of fat and salt are used commonly in the manufacture of biscuits the presence of these bodies cannot in any sense be regarded as an adulteration. In forty-eight samples examined only four were free of notable quantities of added fat. In one case over 16 percent of fat was found, and as it has been shown that all the fat which is added is not extracted by ether it is evident that in this case an amount of fat equal to 20 percent of the weight of the flour may have been used.
It appears, from a study of the composition of biscuits, that it is advisable to use them as a relish or delicacy for eating with cheese, etc., in ordinary daily life, while they become almost a necessity in some form or other in the preparation of emergency rations for marching armies, on shipboard, in logging camps, etc. It is not advisable to employ them in the daily diet to the exclusion of bread. Their nutrient contents have, in comparison with bread, a lower coefficient of digestibility, due largely to the added fat.
Amount of Sugar Lost in Fermentation.
—The total quantity of sugar and other carbohydrates lost in fermentation amounts to about 2 percent of the weight of flour used. Sometimes it is much greater and sometimes less than this. The nutritive value of the product is diminished in proportion to the extent of the loss of sugar. The carbon dioxid produced during fermentation has no food value, and the alcohol is largely lost in the form of vapor during the process of baking. About half the loss is due to carbon dioxid and half to alcohol. The alcohol, although lost mostly during the baking, serves a useful purpose,—in the expansion of the vapor it aids the carbon dioxid in making the bread more porous. The hydrolysis which takes place in baking converts some of the starch to dextrinoid or saccharoid conditions. It is evident that from 6 to 8 percent of total starch present in the flour is changed during the fermentation and baking into more or less soluble forms.
Fig. 36.—Comparative Appearance of Breads of Different Kinds.
Texture and Size of Loaves Made from Different Kinds Of Flour.
—The variations in bread and size of loaves made from different kinds of flour when the conditions of fermentation and baking are the same depends upon the texture and quantity of the gluten material in the flour. The difference in the appearance and size of loaves is shown by a photograph of the cross-sections of three loaves of bread in [Fig. 36].