| 摘要 |
A method of purifying aqueous solutions of iso- alpha -acids by removing beta -acids therefrom comprises first bringing the solution to an iso- alpha -acid concentration of 0.5% to 10% w/w, particularly 0.5% to 5% w/w, then reducing the pH to a value in the range 7 to 10, preferably 8 to 9, so as to form an easily filtered precipitate of beta -acids. Preferably pH reduction is effected by bubbling carbon dioxide through the solution. The separated iso- alpha -acid solution may be concentrated to an extent that a phase separation takes place into two aqueous phases one of which has a higher iso- alpha -acid concentration than the other. The recovered iso- alpha -acid solution is suitable for direct addition to beer without haze formation. |
