Process Aspects of the Extraction of Hops With Liquid Carbon Dioxide

Abstract

The time course of the extraction of a-acids by liquid carbon dioxide was investigated and it has been established that there are two zones with greatly differing rates of extraction. The rate in the first zone is governed by 'solubility' effects, while in the second zone the rate is limited by 'diffusions!' effects. Consequently the rate of extraction in the first zone depends upon the flow rate of liquid carbon dioxide while that in the second zone depends upon the time of extraction. The effects on extraction performance of the depth of the bed of hops and the extent of milling were also explored.

Hop Compounds: Extraction Techniques, Chemical Analyses, Antioxidative, Antimicrobial, and Anticarcinogenic Effects

“…Traditional isolation methods are more and more frequently replaced by the advanced techniques combining sample preparation, separation, detection, and identification. Application of liquid carbon dioxide (LCO 2 ) in the range of temperatures from 20 up to 25 °C and in the pressure range from 50 to 60 bar, respectively, was for example reported in 1966 for the extraction of hops [ 11 , 14 ]. Stability of the obtained extract was however insufficient and has undergone a chemical change during storage.…”

“…CO 2 is thus a substitute for organic solvents of a highly nonpolar character, such as hexane and pentane. The range of organic species which dissolve in LCO 2 includes hop resins and aroma components, paraffins, naphthenes, olefins, alcohols, aldehydes, phenols, esters, carboxylic acids, amines and nitrogen heterocycles, aromates, ketones, ethers, amides, and nitrites [ 11 ], but not polyphenols.…”

“…A large number of natural products has been extracted with carbon dioxide and its commercial applications in the food industry are already well established. The earliest examples of such processes are decaffeination of coffee and production of hop extracts [ 11 ]. Development of such processes and their scaling up are still highly topical.…”

Deodorization of Fish Sauce by Continuous‐Flow Extraction with Microbubbles of Supercritical Carbon Dioxide

“…SC-CO 2 fluid has been applied for the extraction of vegetable oil (Taniguchi and others 1984;Arai and Saito 1986;Zhao and others 1987;Temelli 1992) as well as the separation of highly unsaturated fatty acids from fish oil others 1989, 1990). In addition, the SC-CO 2 extraction of hops (Daoud and Kusinski 1986), caffeine from coffee (Kurzhals 1982), and peel oil (Coppella and Barton 1987;Kalra and others 1987;Shin and others 1992) have been reported. As noted above, extractions with SC-CO 2 have been applied to many kinds of natural products, which were dehydrated or low-moisture materials.…”