Nineteenth century scientists were able to justify the addition of sawdust to ordinary bread by claiming not only its nutritional value but its digestibility. The subject of ‘sawdust bread’ got quite a bit of journal space at the time on account of the possibility of it assisting the feeding of the poor at little cost to the rich during times when wheat prices were high.
Here is an extract from the Proceedings of the New York Agricultural Society in 1868.
“Pereira says, "When woody fibre is comminuted and reduced by artificial processes, it is said to form a substance analogous to the amyloceous (starchy) principle and to be highly nutritious." Schubler states that "when wood is deprived of everything soluble, reduced to powder, subjected to the heat of an oven, and then ground in the manner of com, it yields, boiled with water, a flour which forms a jelly like that of wheat starch, and when fermented with leaven makes a perfectly uniform and spongy bread. …
Tomlinson, in his Cyclopedia, asserts that in Norway and Sweden sawdust is sometimes converted into bread for the people by a similar process; and the newspapers have stated, lately, that Norway was reduced to the necessity of using sawdust bread. So we see that woody fibre, practically as well as theoretically, is nutritious, and that heat will develop this nutriment. Heat will develop it into starch, and the action of an acid is necessary to turn it into sugar. The gastric juice supplies this acid, and after the proper application of heat, can dissolve woody fibre or starch, and probably convert it into sugar before it becomes nutritious. Starch is an element of respiration, and supplies animal heat, and, according to Liebig, the surplus contributes to the formation of fat in animals. ….And it is highly probable that even the trunks of trees, when so reduced, are nutritious.”
There is a recipe for bread containing ‘tree flour’ for the use in prisoner of war camps, which is said to have been published in Germany in 1841. It sounds grim.
50% bruised rye grains.
20% sliced sugar beets.
20% tree flour (saw dust).
10% minced leaves and straw.
Quotation for the Day
O God! that bread should be so dear,
And flesh and blood so cheap!