The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Jul. 15, 1980
Filed:
May. 03, 1977
Derek R Laws, Bexleyheath, GB;
Nigel A Bath, Kemsing, GB;
Colin S Ennis, Chislehurst, GB;
John A Pickett, Kimpton, GB;
Alfred G Wheldon, Galley Wood, GB;
Brewing Patents Limited, London, GB;
Abstract
A method of providing a high quality iso-.alpha.-acid preparation is described. The method involves extracting a high quality primary extract containing .alpha.-acids from hops using liquid CO.sub.2 and isomerizing the .alpha.-acids in the primary extract. The liquid CO.sub.2 extraction is performed at a sub-critical temperature of not less than -5.degree. C. The primary extract contains .alpha.-acids, .beta.acids, hop oil and usually no significant amounts of other organic compounds originating from the hops. In the preferred method the primary extract is not purified and the isomerization is performed by boiling an alkaline solution of the extract. This boiling can be utilized to remove the hop oil. The .beta.-acids can be readily removed by acidifying the solution of iso-.alpha.-acid and filtering off the precipitated .beta.-acids. The iso-.alpha.-acid preparation is of outstanding purity and can be added to beer after fermentation and in particular to bright beer after final filtration to provide bitterness.