GB644483A - Improvements in and relating to the preparation of extracts of coffee and/or coffee substitutes - Google Patents

Abstract

Roasted and ground coffee or coffee substitute, or a mixture of both, is pre-wetted with an aqueous liquid, prior to putting the coffee in the extractor, to such an extent that the ratio by weight of water to solid matter does not exceed 0.5 to 1 and is preferably between 0.25 to 1 and 0.5 to 1, whereupon an extraction is made with water or other aqueous liquid. To obtain a fairly uniform size of particles, the grinding mill is adjusted to give the desired maximum size, and particles smaller than the desired size are removed, as by sieving. The extraction may be carried out by a countercurrent process in a series of extractors, as described in Specification 565,620. When the concentration of the extract has fallen to about 10-25 per cent, some of it is removed for use as the pre-wetting agent and a freshly charged extractor is connected to the last extractor and the first extractor is disconnected. Water, milk or sugar solutions may be used instead of coffee extract as the pre-wetting agent. The extraction may be effected in two stages, firstly at a low temperature, say 15 DEG -30 DEG C. to remove heat-sensitive constituents, and secondly at a higher temperature, say 60 DEG -90 DEG C, to remove the more difficultly-extractible constituents. If the counter-current process is used, extracting liquid at the higher temperature may be fed to the first extractor, the liquid cooling to the lower temperature during its passage through the extractors. If necessary, the liquid may be refrigerated to the lower temperature. The extracting liquid may be water, milk, sugar solution or aqueous coffee extracts. The extract may be further concentrated or dried in vacuo, or spray-dried. To inhibit objectionable changes of flavour, a non-toxic antioxidant may be added either to the extracting liquid or to the final extract.