Today in 1897, US Patent 3977953 A was issued, an invention of Hubert Frhr. Von Hirsch and Alfons Hartl, assigned to the Atlantic Research Institute, for their “Process For the Production of Hulupones.” Here’s the Abstract:
Lupulones, which form a constituent of hop resins which have hitherto been separated and discarded because of their poor solubility, are converted into a hulupone-containing beer-soluble bitter-tasting product by photo-sensitized oxidation in a liquid alkaline medium. However, the oxidation, which is effected by means of oxygen or an oxygen-containing gas in the presence of one or more sensitizing dyes and under the action of visible light, is only partial; it is discontinued when the oxygen consumption resulting from the reaction exhibits a substantial decline, or when the fall in pH occurring during the reaction substantially ceases.
