Patent GB-877784-A (GB)
Title: Improved method and means for making a beverage concentrate
IPC: A23F5/28
Filed: 1958-01-02
Abstract: 877,784. Coffee extracts. CURTISS-WRIGHT CORPORATION. Jan. 2, 1958 [June 9, 1957], No. 228/58. Class 129. Coffee extract is prepared by subjecting roasted ground coffee to an initial extraction step with a cold medium to obtain a first liquid extract and subjecting the partially extracted grounds to a second extraction step with a hot medium to obtain a second liquid extract, at least one of the extractions being carried out in the presence of ultrasonic vibrations. The two extracts may be combined in dried form or in liquid form and then dried. The process is carried out by means of one or more extractors comprising a cylindrical chamber having inlet and outlet ports for coffee grounds and for liquid, a helical conveyer for moving the grounds through the chamber and transducers mounted on the conveyer for subjecting the grounds to insonation. As shown in Fig. 1, ground roasted coffee is fed from a source 50 to an ultrasonic extractor 51 where it is extracted by cold water, the resulting liquid being fed to a clarifier 53 and thence to a drier 56 which may be of the cold temperature type. The extractor 51 may be of the batch, continuous, concurrent or countercurrent type. The grounds from extractor 51 are extracted by hot water in extractor 60 and the extract, after clarification and drying, is mixed in a blender 58 with the first extract and the mixture is then packaged. A centrifugal separator may be provided between the cold extractor and clarifier 53 and the sediment therefrom is fed to hot extractor 60. Hot extraction cells may be charged with alternate layers of grounds and slush ice or with a mixture of grounds and ice. A counter-current extraction system may be set up for cold extraction. The extract may be concentrated by freezing, slushing or vacuum concentration of the hot extract. In a modification of the process shown in Fig. 1, the hot extract may be cooled, e.g. in a tubular heat exchanger, and mixed with the cold extract after which the mixture is dried and packaged. In a further modification the extractor 60 is replaced by an ultrasonic hot extractor and the dryer 56 by an ultrasonic cold temperature dryer. The process shown in Fig. 7 is broadly similar to that of Fig. 1, but the cold extract is passed through a heat exchanger 91 where it is heated and then cooled before passing to a further cooler 95 and thence to clarifier 96 and dryer 98 for completion of the process as before. The clarifier may be arranged before the heat exchanger. In a modification of the process shown in Fig. 7, the cold extract is passed first to a clarifier and then to a slush freezer and an ice crystal separator from which the crystals are returned to the ultrasonic cold extractor. The extract is then passed on to the cold temperature dryer. Several qualities of coffee may be blended as in Fig. 9, some roasted grounds of one type being subjected to hot extraction with ground coffee of another type together with partially extracted grounds of the first type and yet another type, the extracts from two ultrasonic cold extractors and from the hot extractor being separately clarified and dried and then blended as before. Ultrasonic equipment may be used in any of the steps. Fig. 4 shows an ultrasonic extractor of the counter-current type comprising a cylinder 171 containing a hollow screw conveyer driven by a belt 188 for carrying ground coffee upwardly from an inlet 177 to an outlet 178 while extracting liquid passes from an inlet 195 to a screened outlet 206. Transducers 215 and 215A are located respectively on the screw 184 and its shaft 183, both of which are hollow for the passage of a heat exchanging agent or liquid, and further transducers 224A are disposed about the cylinder within a jacket 217 through which coolant, e.g. brine or water, may be passed. The transducers 215 are connected to a power source by cable 216 and slip rings 210, 211 on shaft 183, and transducers 224A are connected, to a similar source by cables 223, 224. In modifications, Figs. 13 and 14 (not shown), the hollow shaft of the extractor has an enlarged hollow portion in the vicinity of the transducers or the shaft may be uniformly enlarged throughout, the depth of the screw at the enlargement being consequently reduced.