Historicai Profiles ofMayo High-Altitude Baking at Mayo In 1949, the Mayo low-pressure chamber served as an experimental kitchen for testing the baking of cakes at high altitudes. At that time, the Army Quartermaster Corps in Chicago had contracted Pillsbury Mills of Minneapolis to develop recipes and prepared mixes suitable for use at various altitudes. The researchers for the army study believed that they could avoid traveling to the various elevations and could eliminate variables in their test results if they could use the controlled conditions produced in the nearby Mayo low-pressure chamber. The Mayo Foundation had built a low-pressure chamber in Rochester, Minnesota, as part of its contribution to the war effort during World War II. Mayo had used this chamber in a series of highly successful military experiments, including the development of the widely distributed BLB (Boothby, Lovelace, Bulbulian) oxygen mask for allied aviators. The pressure chamber was to be dismantled in 1949, but the baking researchers requested that it be available for a final series of military experiments. After receiving permission from Mayo, the researchers managed to squeeze a small electric stove, mixer, scales, table, and other baking utensils into the large horizontally positioned steel tank that formed the pressure chamber. Inside the tank, two researchers carefully weighed and measured the ingredients for the recipes being tested. Because the oven of the stove was small, only one cake, either chocolate or white, could be baked at a time. Before ascending in the "flying kitchen," a control cake was always baked under normal conditions. Afterward, the technicians outside the chamber were signaled, the air lock was secured, and the chamber was prepared for the ascent. The duration of each simulated flight, at a specific altitude, was approximately 4 hours. During that time, communication outside the pressurized kitchen was maintained by external speakers connected to the built-in microphones of the Mayo oxygen masks, which were hanging inside. The small portholes that lined the walls of the pressure chamber facilitated viewing. The baking studies necessitated 64 flights and produced approximately 200 cakes. Seven to 10 cakes were baked daily. These cakes were carefully measured and judged against known standards. Subsequently, they were packed in dry ice and sent to Minneapolis for additional study. The results were then compiled and sent to the military. During the course of the experiments, the temperature and humidity controls on the Mayo low-pressure chamber were found to be stable; thus, the researchers were able to simulate baking conditions successfully at the designated altitudes. The experiments helped "pave the way" for the extensive use of prepared cake mixes that are readily available today. Clark W. Nelson, B.S. Mayo Historical Unit

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67:718, 1992

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