Flour roller mills were specifically designed to efficiently separate the bran and germ elements of the wheat kernel.
[7] At the time, without refrigeration or sealed storage, the heightened water absorption properties of the crushed bran fiber and the oil-rich germ shortened the shelf life of this flour.
Sifting or bolting could separate some of the elements because the thicker bran seed coat of the soft winter wheat varieties would crack into relatively large fragments.
[citation needed] In this era, the limited amount of endosperm that could be sifted into a whiter flour was understandably preferred by consumers.
[10] However, millers worldwide began to experiment with high grinding,[11] or placing the mill stones further apart and turning them at slower speeds.
The white endosperm flour yield was enhanced by the addition of device known as the middlings purifier, which sent a blast of air into the mixture of partially-ground kernels as they were being sifted, lifting the bran particles upward into a separate holding area.
They credited the finer flour that Hungarian millers were able to produce by using more uniform steel rollers instead of mill stones for their higher quality baked goods.
A US Patent number 225,770: Grain-Crushing Roll employing the use of grooved steel rollers geared to mill at different speeds was later granted in the U.S.in 1880 to John Steven .
[15] To enhance output, millers experimented with flour tempering,[16] or hydrating the outer shell of the wheat berry, which facilitates the elimination of the bran and the germ.
The National Labeling Education Act of 1990 provided for federal preemption of standards of identity, nullifying any state laws that made enrichment of flour and bread products mandatory.