Method for isomerisation of hop alpha-acids using heterogeneous alkaline earth metal based catalysts

Abstract

The invention relates to a process for the production of iso-alpha-acids starting from hop alpha-acids in which an hop alpha-acid containing feed is contacted with a heterogeneous alkaline earth metal based catalyst, that essentially does not dissolve in the alpha-acid containing feed or in the iso-alpha-acid product phase, either in solvent-free conditions or in the presence of water, carbon dioxide, or an organic solvent or a mixture thereof. The resulting mixture is subjected to a temperature of at least 293 K, preferably under an inert atmosphere, for a time sufficient to effect high conversion of the alpha-acid reactant into the iso-alpha-acid product. The molar ratio of alpha-acid to earth alkaline metal (Mg, Ca, Sr, Ba) varies preferably between 0.2 and 20. After the isomerization process, the heterogeneous alkaline earth metal based catalyst can be quantitatively separated from the iso-alpha-acid product phase by liquid-solid separation techniques.

Dependencies are inferred from the claim text.