VIEW ARTICLE    DOI: 10.1094/ASBCJ-35-0187

Production of Solvent-Free Isomerized Extracts. Derek R. J. Laws, Nigel A. Bath, and John A. Pickett, Brewing Research Foundation, Nutfield, Surrey, RH1 4HY, Great Britain. J. Am. Soc. Brew. Chem. 35:0187, 1977.

Extraction of hops using liquid carbon dioxide provides a convenient method of obtaining a high-quality yellow product which usually contains over 90% of the available α-acids in the original hops. Under suitably controlled conditions, this solvent does not extract significant amounts of hard resins, fats, waxes, or pigmented materials. Brewing trials using these extracts gave beers of clean flavor which could not be distinguished by taste or analysis from control beers which were hopped in the usual way. Extracts obtained using liquid carbon dioxide can be converted into soluble isomerized extracts, in high yield, by a process involving three simple stages. The isomerized extracts produced in this way are free of residual organic solvents and can be added directly to bright beer without the formation of haze. The resulting beers had a satisfactory shelf life and showed no tendency to gush.

Keywords: Hop extracts, Isomerized extracts, Liquid carbon dioxide, Preparation.