A SYSTEM FOR FILLING CHEESE MOULDS WITH PREPRESSED CHEESE COAGULUM

Abstract: It is known to prepare cheese mass to be filled into cheese moulds by supplying the basic mixture of whey and cheese coagulum to a perforated drain tube, from which the whey is drained off and the remaining cheese mass delivered downwardly to be collected in cheese moulds which are then transferred for ordinary pressing of the resulting cheese curd blocks. It has been found, however, that in this process there are several problems with respect to so-called edge fermentation, and the invention essentially deals with the combatting of these problems in connection with a widely novel production system having a high capacity.

Description: A SYSTEM FOR FILLING CHEESE MOULDS WITH PREPRESSED CHEESE C0A6ULUM The present invention relates to the production of cheese of the Gouda type, i.e. pressed cheeses ideally having a rigid and tight structure with relatively few and middle-sized holes, typically of pea-size. It is the purpose of the invention to provide a method and a system for producing these cheeses or at least for initiating the production in such a manner that the final products may occur as units of a reason¬ ably low price and good quality. These cheeses may be produced in a relatively simple and rapid manner by feeding the cheese coagulum from the curdling tank into an upright perforated drain tube, from which the whey is drained off, such that the drained cheese mass can be delivered to an underlying cheese mould, which is brought to a cheese press for further processing of the cheese mass. Hereby it is avoided that the cheese coagulum should undergo a pre- pressing in a special prepressing vat as otherwise required. However, in this production there are different problems, which have only been partly elucidated and explained. Thus, it is seen regularly that in the outer¬ most 1-2 cm of the cheese there are undesired high concentrations of holes, and in connection with the invention it is found plausible that this phenomenon is due to a special edge fermentation effect giving rise to the fact that in the process air may intrude in the edge area, whereby cavities are formed which will rapidly be filled with whey. These whey pockets present a substrate for aroma making bacteriae that will soon start a production of carbon dioxide, whereby even tiny cavities are blown up into noticeable holes in the cheese. It is known in advance that the coagulum mass should be kept isolated from the air, because an oxidat¬ ion of the cheese grains gives rise to irregular holes in the cheese. Care should be taken, therefore, that the chamber around the drain tube be held whey filled entirely up to the upper operative end of the tube, where the drainage chamber is closed by an annular top plate. The drainage chamber has to be connected with a CIP cleaning system, viz. by way of an upper and a lower pipe connection. The lower connection can be used also for the discharge of the drained whey, while the upper connection is used only for the circulation of the CIP cleaning liquid. During the operation it may happen that by the lowering of the cheese coagulum mixture in the drain tube, some air will be drawn in from the upper CIP supply pipe, such that this air is admixed into the outer layer of the coagulum inside the drain tube, and it may be just this air which is responsible for or may contribute to the said edge fermentation problems. Once the air - or just a bubble - has come into the whey it will locate itself just beneath the said top plate, and in the best case it may pass out through the CIP pipe; however, it may also pass inwardly through the sieve wall and there cause the described damage. Based on these assumptions it is a purpose of this invention to provide a simple arrangement for counter¬ acting the intrusion of air into the drain tube. Accord¬ ing to one aspect of the invention this is achieved in a simple manner by the underside of the said top plate being shaped so as to extend obliquely outwardly and upwardly. Thereby the air bubbles will be prompted to yield upwardly and outwardly, that is to a level in which they are out of contact with the upper end of the drain tube and in connection with the CIP pipe. Experiments have proved that this simple measure has a marked favourable effect on the said problem in the produced cheeses. It is a further purpose of the invention to provide a system that is able to operate with a relatively high capacity and in which special attention is paid to the combatting of the edge fermentation also in other parts of the system, based on assumptions that have proved correct by experiments. In a known system, disclosed in US-A-4,152,101, the partly drained coagulum in the drain tube is supported on a knife blade closing the lower end of this tube. An underlying platform mounted at the end of a vertical piston rod of a working cylinder is raised to a position just underneath the knife blade, which is retracted laterally such that the column of coagulum in the drain pipe now rests on the platform, then the platform is lowered slowly thus bringing the coagulum column correspondingly downwards, even assisted by an air pressure at the top of the column, to a predetermined position, and the knife is actuated to reclose the lower tube end. Thereafter, the platform is urged upwardly, causing the cut-off coagulum block to be compressed against the lower side of the knife blade, e.. through 30-60 seconds, whereby further whey is driven out of the block. Upon a slight relowering of the platform, another cylinder is actuated so as to push the block laterally off the platform. Thus, in this process, it is endeavoured to produce self-carrying cheese block members directly from the coagulum column, and this is bound to be a pronounced slow process. The said compression of the block material will easily create fermentation problems unless the block material is already widely liberated for whey, this requiring a long draining time in the drain tube. In another known system, according to GB-A-2, 125,674, the main function is just the same, but the compressed block member is discharged laterally by the same piston plate that has been used for the compression, in that the entire receiving system beneath the drain tube is pivotally arranged, such that the piston plate, when the system has been turned 90°, can be used to eject the block laterally to some receiver or conveyor means. In connection with the invention, it has been found that already the said known knife plate creates ferment¬ ation problems, viz. in causing a slight compression of the cut-off block material, particularly over the last half of its closing movement, when it approaches the opposite side of the lower mouthing of the drain tube. As it is a major object of the invention to speed up the process, it is necessary to accept a reltively high content of whey in the block material, and this makes the material extra sensitive to local compressions. According to the inventio the said block members are still cut off from the coagulum column with the use of knife plate means, but use is made of two opposed knife plate halves, which are introduced from opposite sides, such that their cutting edges will meet at the middle of the lower drain tube mouthing, thus not caus¬ ing any compression against the respective opposite areas of this mouthing, or for that sake, against or between each other. Furthermore, according to the invention, the cut— off block members are not subjected to any immediate compression, once they have been cut off. To the contrary, they are caused to be deposited in shape retaining receptacles or intermediate moulds that are only slightly larger, such that the block members will be free to expand radially without any building up of local compressions, in response to further axial compression or narrowing. According to the invention the block members cut off from the lower end of the coagulum column are not displaced laterally in any free condition, but are received in an intermediate mould, which is carried, horizontally, into a delivery position, from which the block member can be transferred vertically to an underlying, final cheese mould, in which the block member can finally be processed. Preferably, this inter¬ mediate mould is placed on a carrousel together with one or more similar moulds, whereby it is possible to arrange for some further general compression of the block members without restricting the capacity of the system. In the following, the invention is described in more detail with reference to the drawing, in which: Fig. 1 is a perspective, schematical view of a system according to the invention, Fig. 2 is a perspective view of a knife plate element used therein, and Fig. 3 is a side view of a carrier part shown in Fig. 1. In Fig. 1, the already discussed drain tube or tubular sieve is shown at the top, standing on an apparatus cabinet 2 and designated 4. It comprises an outer tubular housing 6 in which there is arranged a coaxial sieve pipe 8, the perforations of which are preferably made as very narrow, vertically oriented slots 10, e.g. having a width of only 1 mm and a height of about 10 mm. As illustrated, the sieve pipe is divid¬ ed into three sections, each having a lower outlet pipe 12 from the chamber between the outer housing 6 and the sieve pipe and an upper supply pipe 14 leading to the same chamber. At the top and just beneath each outlet pipe 12 there is mounted a filler ring 16, the underside 18 of which is conical outwardly and upwarddly as clear¬ ly shown in the annexed detailed view. The mouthing of the supply pipe 14 has its upper limit located next to the outer circumference of the ring 16 and its lower limit located in level with or slightly beneath the underside level of the ring 16 immediately next to the sieve pipe 8. From a curdling tank a coagulu /whey mixture is fed to the sieve pipe 8, the bottom of which is temporarily closed by a pair of horizontal knife plates 20, which, from the positions shown, are pushed together so as to form a bottom closure of the pipe 8. The whey or the major part thereof escapes through the slots 10 and is brought to fill up the outer chambers in the single sections of the sieve pipe 4, from which excess whey may then be discharged through the pipes 12 , with the use of a suitable sensing and controlling equipment. Underneath the lower end of the sieve pipe 8 and beneath the knife plates 20 there is arranged, inside the cabinet 2, a receiver mould 22, the diameter of which is slightly larger than the inner diameter of the sieve pipe 8. By a retraction of the knife plates 20 the drained coagulum mass in the pipe 8 will sink as a column in a manner such that this column will now be supported by a perforated bottom plate 24 in the receiv¬ er mould 22. When thereafter the knife plates 20 are actuated to be brought together the coagulum column will be severed, whereby a cheese curd body will be isolated in the receiver mould 22, while new coagulum mass to be drained can still be supplied from above. The bottom plate 24 in the mould 22 can be lifted by means of an underlying lift unit shown as a cylinder 26, whereby the bottom plate at the outset can be locat¬ ed just underneath the level of the knife plates 20. Then the bottom plate can be lowered in a controlled manner, thus lowering the entire coagulum column in the pipe 8 until the desired height portion has been receiv¬ ed in the mould 22. Preferably, and contrary to the practice of the prior art, the bottom plate 24 is not used for compressing the block against the underside of the knife plate. In the system shown, the receiver mould 22 is arranged on a rotatable support 28 which can be rotated horizontally about a vertical, controlled turning shaft 30, such that the intermediate mould 22 can be swung into a delivery position, in which the cheese body accomodated in the mould 22 will be located just above a regular cheese mould 32, which has been fed to its position by means of a feeding conveyor 34 extending into the cabinet 2 through a wall opening 36 therein. Above this position there is provided, in or on the cabinet 2, a working cylinder 38, the piston rod of which is connected with a pressure plate 40, which can be urged down for rejection of the cheese member from the intermediate mould 22 to the underlying cheese mould 32 when the bottom plate 24 has been removed as describ¬ ed below. On the rotary support 28 are mounted two opposed intermediate moulds 22, which may thus operate alternatingly. As illustrated in Fig. 3 the perforated bottom plate 24 is ressted loosely in a flat recess in a slid¬ ing plate 23 underneath the support 28, the flat recess having a bottom hole that allows the underlying lift system 26 to lift the bottom plate as described. The sliding plate 23 is connected with a cylinder 25, by means of which it can be displaced to a positon in which it is fully retracted from the lower end of the associated receiver mould 22. The cylinder 25 is actuat¬ ed to this effect when the mould is ready for the transfer of its cheese body to the underlying mould 32. After this bringing down of the cheese body the cheese mould 32 is moved out of the cabinet by means of a conveyor 38, from which the mould and the subsequent moulds are delivered to a proper cheese press, this not being illustrated further. It is preferred to subject the cheese bodies to a light intermediate pressing by means of the pressure plate 40, i.e. prior to the lateral retraction of the mould bottom plate 24. The whey that is pressed out of the cheese members by the action of the pressure plate 40 will just fall down to the bottom of the cabinet 2, and the drained off whey can then be removed by a lower drainage pump 42. As already mentioned, the inclined lower surfaces 18 of the annular cover and partition plates 16 in the tubular sieve 4 will show the effect that any occurring air bubbles at these places will seek upwarly and out¬ wardly instead of inwardly into the sieve pipe 8. As indicated at the lowermost discharge pipes 12, all the pipes 12 and 14 are connected tangentially to the outer tubular housing 6, with an expressed elongated connect¬ ion opening, which will provide for good inlet and out¬ let conditions. The use of the bifurcated cutter and carrier plate 20 at the lower end of the tubular sieve is closely linked with the discussed edge fermentation problem, inasfar as the two plates in meeting at the middle will not at any place locally squeeze the coagulum outwardly towards the edge area of the intermediate mould. To the contrary, it is directly desirable that the curd mass in the intermediate mould should be allowed to expand free¬ ly in the horizontal plane since such a deformation may contribute to the liberation of confined whey; for the same reason the width of the moulds 22 should be some¬ what larger than the width of the sieve pipe 6, while these widths have so far been identical. It has been found that the knife plates 20 may still give rise to edge fermentation problems, viz. in that by their planar friction against the top side of the block member in the mould 22, they may cause a certain cutting-up of the surface of this block member. According to the invention this may be counteracted by way of the undersides of the knife plates having a depression just behind the root of the inclined facet forming the cutting edge, as shown in Fig. 2. The cutt¬ ing edge is denoted S, the said depression R, the inclined facet F, and the said root P. By actuation of the knife plate the inclined facet F will cause a depression of the mass in the mould 22, but soon after the passage of the edge the mass will be free to expand into the depression R, and thereby the resulting cutting up of the block surface will be very slight. For the invention it is important that both the measuring out of the cheese mass, the cutting of the cheese blocks, and the following intermediate pressing in the moulds 22 take place inside a confined chamber, in which a stable temperature and humidity can be creat¬ ed. In the chamber there will be a conceivable passage of free whey, so the temperature can easily be held at the temperature of the whey itself, this being quite suitable. Likewise, it is possible to automatically keep the humidity optimally high, that is at 100°. It may even be advantageous to increase the humidity further, viz. by directly spraying whey onto the cheese mass during its stay in the cabinet 2. By the pressing down of the intermediately pressed cheese blocks from the moulds 22 to the final moulds 32 by means of the pressing plate 40 a phase of free fall may occur, which should be avoided for making the transfer gentle. In a preferred embodiment of the invention this problem is accentuated in that also at this stage it is desirable that the receiver mould 32 be slightly larger than the delivery mould 22, because also at the final pressing it is then possible to provoke an even expansion that promotes the driving out of confined whey. Under these conditions the cheese blocks may particularly well carry out a free fall by their delivery from the mould 22, but according to the invent- ion this may be avoided by the pressure plate 40 being made as a hollow body having a perforated bottom plate 41 and a connection through a conduit 44 to a vacuum source. Thereby a fixed coherence between the pressure plate 40 and the cheese block can be ascertained, until the block has reached the bottom of the mould 32, where¬ after the vacuum can be relieved and the pressure plate 40 lifted to be made ready for the next operation. The final moulds 32 should be preheated in the range of 32-35° C, as a local cooling of the outermost portion of the cheese blocks may easily contribute to the said edge fermentation. Finally, it should be mentioned that the "loading down cylinder" 26, in a preferred embodiment, is constituted by a screw spindle system driven by a step or servo motor, whereby it is possible to control the lowering of the plate 24 for stopping it in accurately controlled positions. In practice, it is very important to control the thickness of the finished cheeses, and even though the thickness will change during the pressing, the "down measuring" of of the coagulum will be decisive for the thickness of the cheeses. This down measuring can well be controlled by simple and inexpensive means, but with a resulting accuracy which is not too good. With the invention it has been recognised that it is advantageous to use the more expensive spindle system, as this will currently produce an improved operation profit. Optionally, the vertical movements of the load-down plate 24 may be effected by an air cylinder, while the said spindle sysstem is only used for the required height adjustments of a lower stop for the movable system.

Claims: C L A I M S : 1. A system for filling of cheese moulds with pre- pressed cheese curd blocks based on a supplied flow of a mixture of whey and cheese coagulum, comprising an up¬ right, perforated drain tube for receiving said flow from above and draining out the whey so as to deliver at its lower end the cheese coagulum as a slightly pre- pressed curd mass, including means for successively severing curd blocks from this mass and for transferring these blocks to cheese moulds that are successively brought to and from the system, characterized in that the means for severing comprise opposed plate knives (20) operable to be moved against each other just beneath the lower end of the drain tube (6,8), such that the knives will meet substantially along a diagonal to the mouthing of the drain tube; the cut off lower block of curd mass is received in an intermediate mould (22) mounted together with at least one additional similar mould on a laterally shiftable support (28) , by which the intermediate moulds can be displaced between the relevant receiver position and a discharge position, which is located above a carrier platform for temporary support of successively supplied cheese moulds (32) and beneath pressing means (38,40) for pressing the curd block from the intermediate mould down to the cheese mould. 2. A system according to claim 1, characterized in that the plate knives are made with planar top sides and with cutting edge areas, which form local thickenings (F,P) on the lower sides of the plates. 3. A system according to claim 1, characterized in that the means for subjecting the curd blocks to an intermediate pressing comprise upper pressing plate means (40) operable to be pressed down into the inter¬ mediate moulds outside of said receiving position and preferably during the stay of the blocks in the said discharge position, and by the said support as a whole, preferably embodied as a carrousel (28) , being placed in a shielded chamber (2) suitable to receive and discharge the whey that is drained off from the blocks by this intermediate pressing. 4 A system according to claim 1, characterized in that in the intermediate moulds there is placed a perforated bottom plate (24) , which, in the receiving position, is raisable towards the closed together plate knives and, upon opening of these, is lowerable through a predetermined height by means of an underlying, preferably impulse motor controlled lift spindle system (26) for bringing down a curd block of a desired height, the plate knives being actuated for closing together upon termination of this lowering, whilst the perforated plate in the delivery position can be retracted from the intermediate mould in being mounted in a holder plate displaceably arranged on said support. 5. A system according to claim 1, characterized in that the means for pressing down comprise a piston plate (40) having lower suction openings which are connectable with a vacuum source, e.g. through a hose (44) . 6. A system according to claim 1, in which the perforated drain tube (8) is surrounded by an outer mantle tube (6) , these co-axial tubes being divided in sections between outfilling ring parts (16) , at the lower edges of which the mantle tube is provided with mouthings for supply pipes (14) for the supply of CIP cleaning liquid, characterized in that the ring parts (16) are shaped with outwardly and upwardly inclined bottom sides (18) for enabling occurring air bubbles to easily yield from the adjacent upper area of the underlying tube section.

Inventors: HANSEN THORKIL KIM, JENSEN BENNY THORUP, HANSEN, THORKIL, KIM, JENSEN, BENNY, THORUP
Applicants: APV PASILAC AS, HANSEN THORKIL KIM, JENSEN BENNY THORUP, APV PASILAC A/S
Application year: 1993
Main classification: A23C19
IPC codes: A01J25