Patent GB-527011-A (GB)
Title: Improvements relating to a method of and apparatus for canning food products
IPC: B65B55/14
Filed: 1938-12-28
Abstract: 527,011. Canning Indian corn, peas &c. AMERICAN CAN CO. Dec. 28, 1938, No. 37603. Convention date, Dec. 27, 1937. [Class 49] [Also in Group XVII] A method of canning Indian corn, peas and other food products of the discrete particle type comprises segregating from a supply thereof a quantity sufficient to fill a single can, sterilizing that segregated quantity by high-temperature heat treatment, extracting some of the heat from the sterilized product, filling it into a sterilized can and sealing the filled can with a sterilized cover. The sterilization is preferably effected by forcing live steam through the product and thereafter confining it and subjecting it to live steam at progressively higher temperatures and pressures. A machine is provided for carrying out the method. As shown, the machine consists of a fixed frame 21 on which is rotatably mounted a cylindrical housing 22 driven by a gear wheel 64 engaging a rack 63 thereon. The housing carries a series of slide units 23 each of which is adapted for the sterilization of a charge of the food product, e.g. Indian corn, and the filling of the charge into a sterilized can. The empty cans k are supplied through a rotary valve l, Fig. 1, to the pockets of a rotary turret 27 in a can sterilizing chamber m through which circulates high-temperature steam supplied by a pipe 28 and discharged through a pipe 29. The sterilized cans are passed by a rotary valve n to a chamber o in which they are filled, charged with brine by a briner p and sealed by a seaming &c. mechanism q, the cans being carried through the chamber by an endless-chain conveyer 32, guide-bars 35, 36 being provided. The chamber o may be filled with saturated steam at low pressure, or with sterile gas at low pressure or may be under high vacuum. The can covers are fed to the sealing device q through a sterilizer r. The sealed cans are discharged through a valve s. Each slide unit 23 is reciprocated during rotation of the housing 22 by the engagement of a roller 92 on a pin 93 secured thereto with a cam groove 91 on the fixed frame 21. The slide 23 has a hopper a which takes a charge of the corn sufficient for one can and which, at the beginning of a cycle of operations, is located beneath the discharge aperture 56, Figs. 1, 8, of a supply reservoir b mounted on the frame 21. Low pressure steam is supplied through a pipe 136 attached to the frame 21, a passage 97 and a grid 95 in the rotary housing 22 and passes up through the descending charge. The slide 23 is moved out of register with aperture 56 and steam is supplied to. the hopper at 240‹ F. leaving through channel 137, Fig. 2, and port 138. The hopper is next moved away from grid 95 and over a filling tube d through which it is fed to the can k. As the corn enters tube d steam at 240‹ F., supplied through perforations 112 in a slide f passes up through it. A plunger h, Fig. 8, which has been retained in its uppermost position by the engagement in a notch 142 therein of a spring plunger 141 is now by engagement of a roller 88, attached thereto by a relief valve by which the pressure is reduced to 20 lbs. per sq. in. The slide f is now moved by a cam track 116, in which engages a roller 114 attached by a pin 115 to the slide, to close the bottom of tube d, pin 89, with a cam groove 90 on the frame 21 moved down into the flared open top of the tube d so that a piston ring 175 thereon is just above the straight bore of the tube, leaving a slight clearance for escape of steam. The tube then passes over a channel on frame 21 through which steam at 274‹ F. is supplied for about 2 seconds, the steam escaping through the clearance at the top of the tube and taking away the last traces of air or other gas into the chamber i from which it is vented. Steam at 274‹ F. is simultaneously supplied to a jacket surrounding tube d, the steam entering through a passage 181 and the condensate leaving through a passage 185. Next, steam is supplied to the tube d, and jacket j at 297‹ F. for about 2 seconds. The plunger h is then lowered to seal the top of tube d and steam at 307‹ F. is introduced into the tube for about 2 seconds, the jacket j being also supplied with steam at 307‹ F. At this point the slide 23 has completed one revolution, and at the commencement of the next revolution the recharging of hopper a begins as the sterilization of the first batch of corn is completed by the supply to the now closed tube d and to jacket j of steam at 312‹ F. for about 2 seconds. Cooling is next effected by circulating cold water through jacket upwards from passage 185 to passage 181, the tube d being simultaneously related for about 3 seconds through the perforations 112 to a relief valve through which liquid is allowed to escape and the pressure is reduced to 45 lbs. per sq. inch then for about 3 seconds to a the cooling-water circulation through jacket being continued, if desired to such a point that a vacuum is created in tube d ; a vacuum will simultaneously be created below the closed slide f to prevent bacterial contamination of the charge in tube d or sterile air, nitrogen or other gas or saturated steam, all at slight pressure, may be supplied to a channel beneath the slide. The filling stage follows in which the slide f is moved by cam track 116 to register a discharge opening 113 with the tube d, a sterile can k is moved below opening 113, and the plunger d is forced by cam track 90 down to push the charge of corn into the tin, which then passes to the briner p. When the hopper a is discharging the corn into tube d the grid 95 is cleaned by means of pins 99 which are pushed through its perforations, the pins being attached to a head 98 which is actuated through a pivoted lever 103 one end of which is connected to a stem 101 in the head 98 and the other end engages, through a roller 108, in a cam track 109 in the machine frame. Steam followed by water and then a mixture of water and steam is next caused to flush through the grid 95 to remove the food particles. A similar pin cleaning device t is provided for the perforations 112 in slide f, flushing with sterile water and steam following the cleaning. After the hopper a has been emptied it is moved away from tube d and brought for cleaning over the now cleaned grid 95, and is washed out by water supplied from above it followed by steam introduced from below grid 95.