CHANGES IN CONCENTRATION OF α AND β ACIDS AND OF ISO‐COMPOUNDS ON HEATING EXTRACTS OF HOPS IN AQUEOUS SOLUTIONS AND UNHOPPED WORTS

Marked losses of α and β acids occurred on heating hop extracts in distilled water, aqueous alkaline solutions, and unhopped worts whether freed from protein or not. After the first stages of the reactions, when very large losses of α adds took place, loss of α acids was matched by gain of iso ‐compounds. β acids were more rapidly and more completely lost than α acids even in aqueous solutions; in worts they were almost completely removed. Precipitation by direct reaction with constituents of the wort occurred with both α and β acids and with iso ‐compounds. Temperature and pH had important effects, the former in particular giving markedly increased losses in the higher ranges. In general the requirements of a unimolecular reaction for loss of both a and β acids were fulfilled. It does not seem possible materially to increase the percentage utilization of hops in worts by conventional procedures. Separation and subsequent isomerization of the α acids would probably be required to bring about any marked Improvement in percentage utilization, and considerable care would need to be exercised in its practical application.