This Day in Leavening

by Michael Mullaney on April 22, 2010

Today marks the 145th anniversary of when storied Rensselaer alumnus Eben N. Horsford received his patent for baking powder. This was a big deal in 1865. Let me tell you why.

In the early 19th Century, baking bread was certainly still more of an art than a science. Here’s what our friends at the ACS say about it:

For more than three millennia, the method of baking bread did not change substantially; that is, until the 1830s when bakers began adding sodium bicarbonate (baking soda) and sour milk to their dough. The lactic acid in the sour milk reacted with the sodium bicarbonate to produce carbon dioxide, which, trapped in the dough, resulted in the desired lightness of the baked bread. The introduction of sodium bicarbonate with an acid marked a significant advance in baking technique. But its applicability was limited since baking powder works better in cakes and biscuits than in breads. As a result, most bread makers continued to use sour dough.

In the 1840s, the innovation of cream of tartar, a by-product of wine production, added some much-needed predictability and uniformity to the process of baking bread. But there’s the thing: the baking soda and cream of tartar needed to be stored separately so as not to cause a chemical reaction.

Enter Eben N. Horsford, who had graduated from Rensselaer in 1838 as a civil engineer, and later lectured at Harvard for many years.

Horsford’s innovation was replacing cream of tartar with calcium acid phosphate, and creating a new manufacturing process. This led to Horsford receiving U.S. patent No. 14,722, on April 22, 1865, for an “improvement in preparing phosphoric acid as a substitute for other solid acids.” With a partner, he formed Rumford Chemical Works.

Here’s what the ACS said about his Horsford’s new process and product:

While the introduction of calcium acid phosphate satisfied the supply problem presented by cream of tartar, the baker still had to mix two products to get a satisfactory leavening agent. Since it was the presence of water which began the reaction process, Horsford solved the problem by drying the ingredients sufficiently. To keep them dry, he added corn starch to the mixture as the vital third ingredient. Horsford had discovered that finely ground calcium acid phosphate and bicarbonate of soda could be mixed with finely divided corn starch to prevent a premature chemical reaction. Corn starch remains an essential feature of most baking powders.

The result: a major national and international windfall of bread. The “recipe” for baking powder hasn’t changed to this day. So next time you’re at a restaurant, take a moment to appreciate there’s a little bit of the “Good ‘ol RPI” innovation in your dinner roll.

Do read more about Horsford at his entry in the Rensselaer Alumni Hall of Fame. Also, the ACS has an excellent bio of Horsford.

The epilogue of Hordford’s story is quite unique. Apparently he gave up many apsects of his life as a chemist, businessman, and professor to research his theory that Vikings long ago landed in Boston and founded a settlement. Here even wrote two books about it. One of them, The Discovery of the Ancient City of Norumbega, you can read online in its entirety here.