A plant for the industrial production of long-life, ready-to-eat, cooked foods

Abstract: A plant is described which includes a continuous heat-processing autoclave (1) for cooking and sterilising food measured into tray-like containers (9). The open containers (9), loaded on to trays (12), are advanced through the autoclave (1) by a conveyor (40) operated stepwise. A cooling chamber (6) communicates at one end with the autoclave (1) through a pre-cooling and air-lock tunnel (7) and at the other with a sterile environment in which a sterile closure unit seals the containers (9) of cooked food.

Description: The present invention relates, in general, to a plant for the industrial production of long-life, ready-to-eat, cooked food. In particular, the invention relates to a plant in which food products arranged in open containers are cooked and/or sterilised on a continuous production line, the containers then being sealed and packaged in sterile conditions so as to obtain, for example, so-called long-life ready meals. In general, in the preparation of cooked foods of the type described, it is necessary to satisfy a dual requirement, that is, on the one hand, to ensure that the product is non-toxic for the entire long-life period stated and, on the other, to keep the physical and organoleptic qualities of the product as close as possible to those of a freshly prepared product. To this end, the prior art offers numerous processes which may be divided into two groups, each based on respective different techniques for providing the heat for the stabilising/sterilising and cooking, that is: 1) processes which use electromagnetic energy (in particular microwaves or infrared radiation) to provide the required heat, and 2) processes which use steam and/or a cooking liquid (for example water, oil and the like). The invention relates to techniques of the second group for which it is well known that the equipment available has such specialised structural and operating characteristics that it is usually impossible to use the same equipment not only to carry out two different processes but even to carry out the same process on two different products, even if these belong to a same product family. This is especially true when the chosen process must be carried out on a continuous production line. It is in fact known that, in order to obtain the best product from an organoleptic point of view as well as that of the product-life, it is necessary to use different temperatures, processing times and pressures not only for different categories of product (such as pasta, meat, game and all types of vegetables) but also for products of the same family but of different thickness, dimensions, consistency, weight or shape. It is therefore understandable that the inflexible application of prior art equipment constitutes a serious problem for all companies interested in producing long-life cooked products, for example ready meals, spread over a broad range of basic products. The few attempts to adapt a plant to producing different cooked products have brought considerable structural and functional problems and have resulted in products which are not totally satisfactory from an organoleptic point of view. The problem forming the basis for this invention is that of developing and providing a technique whereby food products arranged in open containers may be cooked and/or sterilised in a continuous, automatic production cycle in which each step may be controlled accurately and which may be used equally well to produce various products differing in nature, weight, consistency, dimensions and shape. This problem is solved according to the present invention by a plant of the type under consideration and having the characteristics described in Claim 1 which follows. Simply by suitable adjustment of its operating parameters (temperature of the heat treatment fluids, processing times, ambient temperature and pressure and the like), the plant of the invention can produce on an industrial scale: all types of sauce based on tomatoes or tomatoes and vegetables, meat casseroles with potatoes, with peas or with other similar ingredients and components, roast meats, rabbit, hare, wild boar and the like cooked "alla cacciatora" (with mushrooms etc), fish-based dishes and starters in general. The advantages and characteristics of a plant according to the present invention will become clearer from the following description of one embodiment thereof, given with reference to the appended drawings also provided purely by way of non-limitative example. In the drawings: Figure 1 is a schematic plan of a first embodiment of a plant according to the invention for the continuous production of long-life, ready-to-eat, cooked food products (so-called ready meals); Figure 2 shows the plant of Figure 1 partly cut away and on an enlarged scale; Figure 3 is an enlarged perspective view of a particular accessory of the plant of the invention; Figure 4 is an enlarged perspective view of means for transferring the food products to be processed in the plant of the invention; Figure 5 is an enlarged perspective view of a detail of Figure 2 seen from inside; Figure 6 is a schematic perspective view of a device for removing dishes from their respective supports according to the present invention; Figure 7 is a schematic plan view of a second embodiment of a plant of the invention for the production of long-life cooked and/or sterilised food products; and Figure 8 is a schematic elevation of the plant of Figure 7 partly cut away. With reference to Figures 1 to 4, a description now follows of a plant according to the present invention for the continuous production of so-called ready meals, that is of portions of food products cooked and/or sterilised in open containers in which they are then sealed and packaged under sterile conditions. This plant includes a continuous autoclave 1 described in detail in a co-pending patent application in the name of the same Applicant, the contents of which are included here for reference purposes. This continuous autoclave 1 comprises a cylindrical body, with a horizontal axis A, defining a processing chamber 2 in which all the heat treatments required to stabilise and/or sterilise and cook the aforesaid food products can be carried out. The processing chamber 2 is generally a pressurised-steam chamber and is always kept in sterile conditions. An inlet region therein for products to be processed is indicated 3 while an outlet region for processed products is indicated 4. Near the inlet region 3 is a station 8 where the dishes to be processed are prepared, a plurality of these being arranged on one support. In the embodiment of Figure 3, the dishes include a dished container or tray 9 with two compartments 10, 11 and a flat, outwardly projecting peripheral edge 9a, while each support consists of a flat rectangular tray 12 with a number of windows 12a equal to the number of containers 9 to be placed on the tray 12. In the embodiment illustrated, the trays 12 are of a size to take four containers 9 arranged in a line; obviously it is possible, and in some cases advantageous, to use trays of a size to support a plurality of lines of containers 9; in yet another case, described later, the foodstuffs to be processed can be measured into a single large tray, avoiding the need for the dished containers. A chamber for receiving the trays 12 with their containers 9 is schematically indicated 14. In particular, this chamber 14 is of a structure and size to accommodate one tray 12 at a time. The tray-reception chamber 14 extends to one side of the autoclave 1, along a horizontal axis B perpendicular to the axis A of the autoclave, and communicates with the inlet region 3 of the processing chamber 2 through an air-lock chamber 15. The air-lock chamber 15 is also outside the autoclave body 1 and extends along the same axis B as the tray-reception chamber 14. Like this latter, the air-lock chamber 15 is of a size to accommodate one tray 12 at a time, arranged along the axis B. With reference to Figure 2, the air-lock chamber 15 communicates at one end with the tray-reception chamber 14 through a first circular aperture 16 formed as a valve seat and at the other end with the inlet region 3 of the processing chamber 2 through a second circular aperture 17, also formed as a valve seat. A first lead-screw arrangement, generally indicated 18, comprising a screw 19 and a rotatable threaded sleeve element 20, is supported along the axis B outside the tray-reception chamber 14 at the opposite end thereof from that opening into the air-lock chamber 15. At one end, the screw 19 has an obturator disc 22 structured and dimensioned to cooperate with the valve seat aperture 16 so as to seal the air-lock chamber 15 hermetically when required. A second lead-screw arrangement (24-25), identical to the first and generally indicated 23, is also supported along the axis B outside the autoclave body 1 at the opposite end thereof from that which communicates with the air-lock chamber 15. The screw 24 of this lead-screw arrangement extends through the cylindrical wall of the body 1, with the interposition of seal means, not shown, and the end thereof inside the body 1 has an obturator disc 26 coaxially fixed to it which is structured and dimensioned to engage the valve seat aperture 17 and to seal the air-lock chamber 15 hermetically. A pair of horizontal, parallel tines 13a, 13b is fixed to that face of the obturator disc 22 facing the aperture 16 for supporting the opposite, longer sides of a tray 12. The tines 13a, 13b form a sort of pusher arm P1 driven by the screw 19 for supporting the trays 12 and moving them along the axis B towards the air-lock chamber 15, as will become clear later in this description. In exactly the same way, the ends of a respective pair of horizontal, parallel tines 28, 29, of about the same length as the trays 12, are fixed to that face of the obturator disc 26 facing the aperture 17 of the air-lock chamber 15 to form a second pusher arm P2. These tines 28 and 29 are mutually spaced by a greater distance than that separating the previously mentioned tines 13a, 13b with which they cooperate to introduce the trays 12 into the processing chamber 2 one at a time, as will be explained later in this description. The free ends of the tines 28, 29 (Figure 4) support respective idle rollers 30, 31 having horizontal axes of rotation perpendicular to the tines themselves. The diameters of the rollers 30, 31 and the positions of their axes are chosen so that the rollers project above the upper edges of the respective tines 28, 29. Near the obturator disc 26, the tines 28, 29 have respective identical teeth 32, 33, substantially like the teeth of a saw, arranged with their inclined (or dorsal) edges 32a, 33a facing the free ends of the tines. These teeth 32, 33 are intended to engage corresponding slots 34, 35 in the short sides of the trays 12. Each of the tines 28, 29 also has identical notches 36, 37, of a predetermined width, opening into the upper edges of the tines themselves; the notches 36, 36 are aligned in a direction perpendicular to the tines, as are the notches 37, 37. A horizontal conveyor of the type known as a stepping conveyor generally indicated 40, extends longitudinally through the processing chamber 2 in the autoclave body 1, preferably in a diametral plane thereof, and is supported by conventional means, not shown. In a preferred embodiment (Figures 2 and 5) this conveyor includes a first pair of mutually-spaced, flat, profiled members 41, 42, supported on edge and extending parallel to the axis A from the inlet region 3 to the outlet region 4 of the processing chamber 2, and a second pair of movable, flat, profiled members 43, 44 supported on edge between the profiled members 41, 42. The fixed and movable members each have equal pluralities of rectangular recesses 45, 46 formed in their upper edges, these recesses having a length and depth equal to the width and depth respectively of the trays 12 so that they can engage the trays and hold them in transversely-extending positions during the movements of the conveyor, as will be explained later in this description. The movable profiled members 43, 44 are mutually spaced by a distance equal to the space between the notches 36, 37 in the tines 28, 29 and are of such a thickness that they can slide in these notches 36, 37. In addition, the profiled members 43, 44 are fixed to each other by a plurality of cross-members 47 so as to form a movable rigid frame. This movable frame is connected by a drive transmission to equipment which can drive its movement in the rectangular path required to advance the conveyor 40 stepwise. In relation to the fixed profiled members 41, 42, this rectangular movement includes: a horizontal movement into a position in which the movable profiled members 43, 44 engage the notches 36, 37 in the tines 28, 29, passing under the tray supported on these tines 28, 29; a vertical upward movement out of the notches 36, 37 so as to lift the tray 12 from the tines 28, 29; a horizontal movement away from the said tines and, finally, a vertical downward movement returning to the starting position, simultaneously delivering the tray 12 collected from the tines 28, 29 to the fixed profiled sections 41, 42. Since the equipment for driving the conveyor 40 and the transmission means connecting it to the movable frame are known per se, they are neither described nor shown in detail here. To advantage, the equipment described in relation to the continuous autoclave which forms the subject of a co-pending Patent Application by the same Applicant may be used. Ducts 39, 39a extend longitudinally through the processing chamber 2 for delivering and metering the fluids required for the heat-processing of the food portions in the containers 9. A lead-screw assembly 48-49 with a rotatable threaded sleeve element is fixed to the outside of the outlet region 4 (Figure 1) of the body 1 and is rotatable by drive means, schematically indicated 50. One end 51 of the screw 48 projects into the outlet region 4 of the processing chamber 2 and an obturator disc 52 is fixed coaxially to this end 51, being structured and dimensioned to form a pressurised-fluid-tight seal with an valve seat aperture 53 which puts the outlet region 4 of the processing chamber 2 into communication with a further, pre-cooling air-lock chamber 7 which extends outside the autoclave body 1 along a horizontal axis C perpendicular to the axis A of the autoclave. A straight pusher arm P3 is fixed to that face of the obturator disc 52 facing the valve seat 53, extends parallel to the axis C and has the same structure and dimensions as the pusher arm P1 described above with reference to the inlet side of the processing chamber 2 so as to support a tray 12. The chamber 7 communicates through a valve seat aperture 55 with the inlet side 6a of a cooling chamber 6; an obturator disc 56 cooperates with the aperture 55 and is fixed coaxially to the free end of a screw 57 driven by an appropriately driven threaded sleeve element extending along the axis C and supported for rotation outside the chamber 6 at the opposite end from the air-lock chamber 7. A pair of tines 59, 60 is fixed to the face of the obturator disc 56 facing the valve seat 55 so as to form pusher arm P4, the tines being spaced so as to receive between them the pusher arm P3 with which they must cooperate as described below. A stepping conveyor, generally indicated 61, operates in the sterile chamber 6. This conveyor 61, and the drive means thereof, will not be described in detail as they are the same as the conveyor 40 and its drive means, described in connection with the autoclave body 1. The components of this conveyor 61, which are the same as those of the conveyor 40, are indicated by the same reference numerals with the addition of 100. About half-way along its length, the chamber 6 communicates (Figure 1) through a tubular passage 62 with another chamber formed in a body 63 fixed to the side of the chamber 6. A delivery-metering unit 64 for sauces or other condiments is fixed above the tubular passage 62 which is sealed both to the chamber 6 and to the body 63 by suitable flanges and seals. A closure assembly, not shown as it is known per se, operates under sterile conditions inside the body 63 to seal the containers 9 which are regularly transferred from the chamber 6, as described later. For this transfer, an expulsion assembly 65 (Figure 6) is arranged in the chamber 6 under the conveyor 61 for releasing the containers 9 from their respective trays 12. The assembly 65 comprises essentially a horizontal, rectangular, plate-like element 66 having the same transverse dimensions as the trays 12; this element 66 has a plurality of parallelepipedal projections 67 of such a thickness that they can engage the windows 12a. The rectangular element 66 is mounted on a plurality of shafts 68 driven to move vertically by actuators in themselves known, preferably mechanical actuators. It should be noted that, when the projections 67 of the element 66 have engaged the windows 12a in a tray 12 to "expel" the respective containers 9 therefrom, they form a continuous support plane with the tray 12 along which the containers 9 may be moved (sliding) without hindrance. A rectangular grid 70, with large rectangular openings 70a is supported above the conveyor 61, extending parallel to the element 66. Each opening 70a is dimensioned so as to surround a container 9. The grid 70 is movable transverse the direction in which the conveyor 61 advances. The drive means for the grid are outside the body 5 and are shown schematically at 38 in Figure 1. By means of these drive means 38, the grid 70 and the plurality of containers 9 engaged in its openings 70a may be moved laterally off the conveyor 61 onto a shelf 71 extending through the tubular passage 62 where the dispenser 64 for delivering sauces or other similar condiments operates. The shelf 71 is aligned with the working plane of the closure assembly, towards which the containers 9 filled with cooked food are conveyed to be sealed. The trays 12, once relieved of the containers 9, are carried by the stepping conveyor 6 towards the outlet zone 6b of the chamber 6 where they are ejected through an aperture 72 by a pusher 73 (either a lead-screw assembly or driven pneumatically.) The autoclave of the invention operates as follows> In a starting condition, the pusher arm P1 and its obturator disc 22 are fully withdrawn into the tray-reception chamber 14 while the pusher arm P2 is fully inserted in the inlet region 3 of the processing chamber 2 and its obturator disc 26 hermetically seals the valve seat aperture 17. The air-lock chamber 15 is then open to the chamber 14 but hermetically sealed from the chamber 12. The pusher arm P3 is fully inserted in the cooling and air-lock chamber 7 which is therefore closed to the outlet region 4 of the processing chamber 2; the pusher arm P4 is also fully inserted in the chamber 7 which is thus also hermetically sealed from the chamber 6 as a result of the obturator disc 56 engaging the valve seat 55. The description which follows refers to a single tray 12 carrying four containers 9 with respective quantities of food to be processed. In the chamber 14, the tray 12 under consideration is positioned on the pusher arm P1. Under the action of the lead-screw assembly 18, the arm P1 and the tray 12 supported thereon are moved towards and into the air-lock chamber 15 where the tray 12 is transferred from the arm P1 to the tines 28, 29 of the arm P2 while, at the same time, the obturator disc 22 seals the corresponding valve seat aperture 16, hermetically closing the air-lock chamber 15 at that end adjacent the tray-reception chamber. The lead-screw assembly 18 is stopped while the lead-screw assembly 23 is activated, thereby moving the arm P2 and its associated obturator disc 26 away from the air-lock chamber 15 and from the valve seat 17. This movement continues until the tines 28 and 29 of the arm P2, together with the tray they are supporting, are fully inside the inlet region 3 of the processing chamber 2. At this point, the stepping conveyor 40 is started and, in a first step, moves the movable profiled members 43, 44 towards the tray 12. With this movement, the profiled members 43, 44 engage the notches 36, 37 in the tines 28, 29, being inserted under the tray 12. Subsequently (second step), the movable profiled members 43, 44 are raised and carry the tray 12 away from the tines 28, 29. With the subsequent horizontal movement (in the direction opposite that previously considered) and downward movement, the cyclic movement of the stepping conveyor 40 in its rectangular path is completed and, at the same time, the tray 12 is laid on the fixed profiled members 41, 42. At this point, the arm P2 and its associated obturator disc 26 are returned to the air-lock chamber 15 with the sealing of the valve seat 17. Once this is closed, the arm P1 can be returned to the chamber 14 to receive a new tray 12 with its containers. The conveyor 40 continues to operate and the tray 12 is advanced stepwise towards the outlet region 4 of the chamber 2. During this passage, the food contained in the various containers 9 is subjected to planned heat processes, for example pasteurisation and/or sterilisation and/or cooking by the processing fluids delivered by the ducts 39 and 39a. By movements exactly the reverse of those described for the collection of the tray 12 from the arm P2, the conveyor 40 delivers the tray 12 and its containers of processed food to the arm P3. A transfer trolley associated with, and cooperating with, the conveyor 40 is used in this last operation. The trolley is not described here since it is identical to that described and illustrated with reference to a continuous autoclave forming the subject of a co-pending patent application by the same Applicant. The lead-screw assembly 48, 49 is now started and transfers the pusher arm P3 with the tray it supports into the cooling and air-lock chamber 7. At the end of this movement, the pusher-arm P3 is fully inside the chamber 7 while the obturator disc 52 fixed thereto seals the corresponding valve seat aperture 53. In the cooling and air-lock chamber 7, the tray 12 passes from the arm P3 to the arm P4 with the food undergoing a first cooling during this movement. When this move is complete, the lead-screw assembly 57, 58 is activated and the arm P4 and its associated obturator disc 56 are moved out of the cooling and air-lock chamber 7 into the inlet zone 6a of the chamber 6 where the processed food is completely cooled. While it is in the chamber 6, the tray 12 is collected by the conveyor 61 and advanced into the centre of the chamber itself, while the obturator disc 56 returns to close its valve seat 55. The expulsion assembly 65 operates in the centre of the chamber 6 to free the containers 9 from the tray 12 and move them one at a time onto the shelf 71 which extends to one side of the conveyor 61, perpendicular thereto. Once the last container 9 has been removed, the free tray 12 continues towards the outlet end 6b of the chamber 6 while the containers 9 are pushed through the passage 62 into the chamber 63 where the closure assembly seals them under sterile conditions. Figures 7 and 8 show a variant of the plant of the invention. In particular, in this plant the food products to be processed are measured into large open containers, essentially large trays, each of which is shaped and dimensioned so as to fit longitudinally into the air-lock chambers and transversely on the stepping conveyors of the autoclave and the cooling chamber. To advantage, the above plant is designed as a closed loop. Also in this variant, the plant of the invention includes an autoclave 72 the inner chamber of which, equipped for heat-processing food products, has tray inlet and outlet regions in communication with respective air-lock chambers 73, 74 extending to the same side of the autoclave. A tray-reception chamber 75 communicates at one end with the inlet-side air-lock chamber 73 and at the other with a tray-conveyor system, schematically indicated at 76, which extends perpendicular to the axis A of the autoclave. The means 77 for transferring the trays from the reception chamber 75 to the air-lock chamber 73 (means which may be constituted by a lead-screw assembly as described with reference to Figure 1 or by pneumatic means or the like) operate along a straight line parallel to the axis A of the autoclave. The air-lock and cooling chamber 74 communicates at its outlet end with the inlet region of the cooling chamber 78 which, it should be remembered, is sterile. This cooling chamber 78 extends parallel to the autoclave 72 and towards the inlet region thereof. The cooling chamber 78 communicates with a sterile tank 79 for collecting the processed product arranged beneath the cooling chamber 78 itself; a tray-emptying device, schematically indicated 80, is arranged in the cooling chamber 78 in correspondence with the sterile tank 79 and is preferably constituted by a device for tipping the trays. Once emptied of the processed product, the trays are removed from the cooling chamber 78 by transfer means 81 and are collected in a further chamber 82 from whence they are sent to a washing station 83 and are subsequently returned by a conveyor system 84 extending parallel to the autoclave 72 to the conveyor system 76 mentioned above, thus closing the loop of this embodiment of the plant of the invention. The sterile tank 79 into which the processed (stabilised and/or sterilised, cooked) product is emptied may be in fluid communication, through one or more outlets 79a, with respective ducts for supplying, for example a sterile filling machine 85 for filling bags of a few kilograms up to 25-30 kg; a sterile filling machine 86 for filling bags of 50-250 kg or 400-1200 kg; a sterile filling machine 87 for filling paper cartons; a filling-metering machine 88 for filling a vast range of glass jars and the like. It should be noted that an expulsion device 65 of the type described with reference to Figure 6 could be arranged in the cooling chamber 78 since, although this device is not used in this second plant (in which the food products are loaded into large trays), it would make it suitable for use with products measured into dished containers supported on flat trays (like those described in the first plant).

Claims: A plant for the industrial production of long-life, ready-to-eat cooked food, including: a continuous autoclave (1) defining a food-processing chamber (2) having an inlet region (3) for food to be processed in respective open containers (9) and an outlet region (4) for the processed foods, and including means (39, 39a) for delivering and metering fluids for cooking or heat-sterilising the foods, first and second air-lock chambers (15, 7) arranged to the side of the autoclave (1) and communicating with the inlet end (3) and the outlet end (4) respectively thereof through corresponding apertures (17, 53) having valve and valve-closure members (26, 52), first and second transfer means (P2, P3) for transferring the open containers (9), filled with food, from the first air-lock chamber (15) to the said inlet region (3) and from the said outlet region (4) to the second air-lock and cooling chamber (7), a sterile food-cooling chamber (6) communicating with the second chamber (7) through an aperture (55) having valve closure members (55), a known closure device for hermetically sealing the containers (9), operating in a sterile chamber (63) communicating with the sterile cooling chamber (6), means (P4, 38) for transferring trays (12) with the containers (9) from the second cooling and air-lock chamber (7) to the cooling chamber (6) and subsequently to the closure device. A plant according to Claim 1, characterised in that the first air-lock chamber (15) communicates, at its opposite end from the autoclave (1), with a container-reception chamber (14) through an aperture (16) with valve obturator means (22), means being provided for transferring the trays (12) with the containers (9) from the reception chamber (14) to the first air-lock chamber (15). A plant according to Claim 1, characterised in that a plurality of the containers (9) are arranged in at least one line on a support tray (12). A plant according to Claim 3, characterised in that the containers (9) each comprise a dish-shaped body with a flat peripheral edge (9a) projecting outwards. A plant according to Claim 4, characterised in that the support trays each comprise a flat element (12) with a plurality of windows (12a) arranged in at least one line and of such a size as to be engageable by the bodies of the containers (9). A plant according to Claim 1, characterised in that a conveyor (61) operated stepwise extends inside the cooling chamber (6) from the inlet end (6a) to the outlet end (6b) thereof. A plant according to Claim 6, characterised in that the cooling chamber (6) communicates with the sterile closure device through a tubular passage (62) in which a delivery-metering unit (64) operates to dispense condiments in general. A plant according to Claim 7, characterised in that an expulsion assembly (65) is arranged in the sterile cooling chamber (6) adjacent the tubular passage (62) for releasing the containers (9) from their respective support trays (12). A plant according to Claim 1, characterised in that the sterile cooling chamber (6) communicates with a sterile tank (79) for collecting the processed products, a device (80) being provided in this region for emptying the containers. A plant according to Claim 9, characterised in that the sterile tank (79) is in fluid communication through one or more outlets (79a) with respective ducts for supplying sterile filling units (85, 86) for filling bags, sterile filling units for filling cartons (16) and a sterile filling-metering units (17) for filling glass jars and the like.

Inventors: CATELLI CAMILLO, NOTARI ROBERTO, CATELLI, CAMILLO, NOTARI, ROBERTO
Applicants: ROSSI & CATELLI SPA, ROSSI & CATELLI S.P.A.
Application year: 1995
Main classification: B65B55
IPC codes: A23L3, B65B25