T. K. Walker, N. Blakebrough
Jan 2, 1952
Citations
0
Influential Citations
12
Citations
Journal
Journal of The Institute of Brewing
Abstract
Humulone boiling-product has been prepared by boiling humulone in presence of alkali in an atmosphere of nitrogen and was recovered by ether extraction. Its bacteriostatic potency against 10 strains of Lactobacillus has been compared with that of humulone by determining growth inhibition in cold-water malt extract and in malt wort and beer, by the log phase method (wort medium), and by measuring the restriction of acid production in beer. In malt extract (pH 5·5), wort (5·2), and by the log phase method, the boiling-product (as also beer soft resins by log phase) has 43–46% of the bacteriostatic potency of the original humulone; the potencies of both increase as the pH falls to that of beer, and at pH 4·3 there is no significant difference between them. Since by the log phase method (wort medium) 10–20% of the humulone activity remains in beer, it follows that the recovery in beer of soft resins (principally isohumulone) is 23–46% of the weight of humulone used.