Patent GB-522957-A (GB)
Title: Improved process of and apparatus for treating food products
IPC: A23L3/04
Filed: 1938-12-20
Abstract: 522,957. Preserving food ; conveyers. CROWN CORK & SEAL CO., Inc. Dec. 20; 1938, No. 37088.. Convention date, Jan. 19. [Class 49] [Also in Group XXX] A process of treating foods in containers each having an end with a valve therein closable by pressure within the container, comprises introducing sterilizing steam into the container and contents, causing the valve to close the container and maintaining an external pressure about the container in a closed chamber approximately the same as the internal pressure, to avoid strain on the cans. The cans are pushed, by a reciprocating rod 30, from a conveyer 10 into pockets in a rotary valve member 11, each pair of diametrically opposed pockets being connected by a sliding pusher 28 which is pushed in, by the entry of a can from the conveyer 10 to a pocket, so that the can in the opposed pocket is deposited on a conveyer 13 in a chamber 12 in which a vacuum of from 12-29 inches of mercury is maintained. A conveyer is arranged above the conveyer 13 and carries pins which are spaced to correspond with the spacing of the cans on the conveyer 13, the pins being acted upon by a stationary cam rail to bear upon the valves of the cans and open them, so that the contents are properly vacuumized. The pins have springs tending to withdraw them from the valves. A second rotary transfer-apparatus 30, 11 places the cans upon a conveyer 15 in the sterilizing chamber 14, the cans being inverted during their passage through the chamber, e.g. by a screw-member 14<SP>1</SP>. The cans may be restored to an upright position before leaving the chamber through the third rotary transfer apparatus. The valves are held open by the external steam-pressure in the chamber 14, the steam thus entering the can and effecting its greatest heating-effect on the contents by condensation. Sterilizing temperatures of 287‹ and 288‹F., and a pressure of 40 pounds per square inch are mentioned. A lower pressure is maintained in the final chamber 17 which is traversed by the conveyer 18. The valves of the cans close during the transfer because of the excess of internal pressure, and the external pressure in the chamber is such that any internal strain on the container is avoided. The cans are finally discharged on to the conveyer 19 for further operations such as crimping the valves on the ends of the cans, cooling, labelling &c. The high pressure chamber 15 may be divided into several sealed sections, in which the temperature may be successively increased or decreased from the receiving end, e.g. a temperature of 250‹ to 259‹F. and a pressure of 15 to 20 pounds per square inch in the first compartment, and a temperature of 280‹ to 292‹F. and a pressure of 35 to 45 pounds in the second compartment, when two compartments are provided, and the chamber 17 may, likewise, be sub-divided. A pressure of 15 to 20 pounds is maintained in the chamber 17 by means of air, steam or water vapour or air and water vapour, water or any other cooling fluid, the cans being finally passed into the atmo -  sphere at a temperature of about 250‹F. and an internal pressure of about 20 pounds per square inch. In a modification of the process, the cans are placed in a turret rotating in a vertical plane, so that, during a rotation, the can is inverted. During the first stage of a revolution, a high vacuum is applied to the can, after which steam is injected into the can to sterilize the contents and seat the valve. The can is removed from the turret with the valve downwards and conveyed to a high pressure steam chamber, inverted and discharged into a compensating pressure chamber. The inverting means 14<SP>1</SP> may be replaced by a rotary valve similar to the valves 11, but rotating in a vertical plane.