Patent GB-615514-A (GB)
Title: A method of producing butter by cooling cream of high concentration
IPC: A23C15/06
Filed: 1942-12-22
Abstract: Cream of a high fat content is produced by centrifugal separation in two or more stages, the amount of fat fed into the separator bowls being determined according to the speed of the bowl, the temperature and the centrifugal force of the inlet zone so that sufficient membranes enclosing the fat globules are removed to ensure conversion of phase on cooling, and the cream is conducted, without being mixed with air, through pipe lines, tightly connected to the bowl or bowls, in the last stage or to scraping or paring devices extending into a liquid layer rotating with the bowl or bowls, into a container and thence through pipe lines to cooling means in which the cream is converted into butter.  Comparison of the fat content of the skim milk as determined by the Rose-Gottlieb method with that calculated from a microscopic examination shows whether sufficient membranes have been removed from the fat globules.  Preferably in the last stage, the temperature is at least 85 DEG  C., the separators are regulated for a water content of 20 - 22 per cent, the inlet zone of the bowls is located at a greater distance from the rotation axis than in previous stages, i.e. in or outside the middle zone of the separating chamber, and a constant pressure at the outlet is maintained by means of automatic throttles.  After mixing the cream in the container by means of a stirrer or by rotating the container, the water content is adjusted, if necessary, by adding water, skim milk, whole milk or cream or by evaporation, the container being adapted to be heated under vacuum.  Salt, aromatic substances and a colouring agent may be added to the cream in the container or the colouring agent may be added between separating stages or in the last stage.  The cream may be cooled while being stirred in the container by keeping the latter at a low temperature, preferably 20 - 25 DEG C. by means of a cooling liquid, the stirrer preferably corresponding in shape to the wall of the container and being provided with resilient scrapers. Alternatively, the cream may be cooled before entering the container by passing it through a plate or tube-type heat-exchanger, which may be coupled with a pasteuriser of similar construction, a pump being used to avoid too high a counter-pressure at the outlets of the separators.  The cream is finally cooled to a temperature of 10-17 DEG  C. before it is discharged from the container.  A rapid cooler, in which the cream is cooled below the conversion temperature but without conversion, may be provided between the container and the final cooling means in order to reduce the time required for conversion in the latter.  The Specification as open to inspection under Sect. 91 comprises also the separation of the cream in one stage only, the construction of the container as a cube rotatable about a shaft through two opposite corners, and the conversion of the cream into butter in barrels or other small containers, preferably rectangular cases of small height, placed in a refrigerating room. This subject-matter does not appear in the Specification as accepted.