Anselme Payen and Jean-François Persoz Isolate Diastase from Malt

In 1833, chemists Anselme Payen and Jean-François Persoz isolated a starch-converting substance from an aqueous extract of germinated barley malt. They precipitated the active material with alcohol and obtained a white, water-soluble powder that retained a powerful effect on starch after it had been separated from the grain. They named the substance diastase, drawing on a Greek word associated with separation. Payen and Persoz showed that very small quantities of the preparation could liquefy starch paste and convert the starch into soluble products, including sugar and dextrin. The disappearance of starch could be followed with iodine, while heating the preparation destroyed its activity. Their experiments therefore distinguished the active substance from the malt itself and demonstrated that its starch-converting power could operate outside the germinating grain. Diastase was later understood not as a single pure substance but as a mixture of starch-degrading enzymes now classified among the amylases. Commonly described as the first enzyme to be isolated, it became an important milestone in the development of enzymology. For brewing science, the discovery helped explain the activity already exploited during malting and mashing, in which malt enzymes break down grain starch into fermentable sugars and dextrins.