Abstract: A method and apparatus for removing water from a liquid mixture of water and ethanol contacts it with liquid carbon dioxide so that the ethanol is preferentially transferred into solution, dries the solution using an adsorbent, and then recovers dry ethanol by distilling off the carbon dioxide. This process is particularly energy efficient especially when it includes a fermentation process to generate the ethanol and uses the carbon dioxide generated during the fermentation as the source of liquid carbon dioxide. In this case the method and apparatus provide an additional product of dry carbon dioxide.

Abstract: A method and apparatus for removing water from a liquid mixture of water and ethanol contacts it with liquid carbon dioxide so that the ethanol is preferentially transferred into solution, dries the solution using an adsorbent, and then recovers dry ethanol by distilling off the carbon dioxide. This process is particularly energy efficient especially when it includes a fermentation process to generate the ethanol and uses the carbon dioxide generated during the fermentation as the source of liquid carbon dioxide. In this case the method and apparatus provide an additional product of dry carbon dioxide.

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.

Abstract: A method of preparing an extract from hops comprises contacting the hops to be extracted with carbon dioxide in the liquid state to dissolve the matter to be extracted in the liquid carbon dioxide, heating the solution of extract to evaporate carbon dioxide from the solution of extract, compressing and condensing the evaporated carbon dioxide vapor to re-form liquid carbon dioxide, and re-cycling the liquid carbon dioxide to contact the material to be extracted. At least part of the heat evolved from the carbon dioxide vapor after its compression and during its change of state from vapor to liquid carbon dioxide is used to cause the change of state of the liquid carbon dioxide in the solution of the extract to evaporate the carbon dioxide from the solution of the extract.A plant for the preparation of an extract of hops by extraction with liquid carbon dioxide is also disclosed together with modifications of the plant to enhance the recovery of hop oils or to obtain a separate extraction of the hop oils.

Abstract: A method of preparing an extract from a material comprises contacting the material to be extracted with carbon dioxide in the liquid state to dissolve the matter to be extracted in the liquid carbon dioxide, heating the solution of extract to evaporate carbon dioxide from the solution of extract, compressing and condensing the evaporated carbon dioxide vapor to re-form liquid carbon dioxide, and re-cycling the liquid carbon dioxide to contact the material to be extracted. At least part of the heat evolved from the carbon dioxide vapor after its compression and during its change of state from vapor to liquid carbon dioxide is used to cause the change of state of the liquid carbon dioxide in the solution of the extract to evaporate the carbon dioxide from the solution of the extract.

Abstract: A method of preparing a hop extract is described in which liquid carbon dioxide is passed at a temperature of from -5.degree. C. to +15.degree. C. through a column of hop material to extract .alpha.-acids contained therein. The method gives a primary extract which is of much higher purity than has been previously described particularly in comparison to presently commercially available solvent extracts.

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.

Abstract: A detector for detecting the presence of a particular gas in a mixture of gases comprises a space bounded in part by a membrane which is preferentially permeable to the particular gas and bounded in part by a thin flexible diaphragm. The diaphragm is arranged to control flow through a nozzle to which, in use, a gas is supplied at a steady pressure, and means are provided to supply the mixture of gases to one face of the membrane. In use, when the particular gas is present in the mixture being supplied to the one face of the membrane the particular gas permeates through the membrane from the one face to change the pressure in the space and cause the diaphragm to bow and produce a change of pressure in the supply of gas upstream from the nozzle. The change in pressure in the supply of gas upstream from the nozzle constitutes a pneumatic signal indicating the presence of the particular gas in the mixture. The membrane and the thin flexible diaphragm may be formed from the same piece of material.