Pasteurization, sterilization and aseptic packing procedure for meat products and machine therefor.

<u>BACKGROUND OF THE INVENTION</u>

This invention relates to a procedure for processing perishable meat products, such as a piece of ham or shoulder meat, which having sustained deboning, additives and/or ingredients injecting (auxiliary to namely coloration and taste), tenderizing, massing and curing operations, is later on submitted to a cooking-pasteurization stage, inside a rigid or semi-rigid mould protected by a continuous (open bag) wrapping, at room temperature or in vacuum, after which stage it is demolded and taken apart from that wrapping to eliminate fluids exuded during the cooking-pasteurization process and for a suitable conditioning of the product surface, being finally repacked, advantageously in vacuum in tight conditions by means of different sealing means (stapling, heat-sealing etc.).

Above procedure is mainly used to obtain high quality products, in which an exudation during the cooking-pasteurization stage is sought, in order to achieve a best development of flavour and aroma. The fact of being not necessary to prevent the juice exudation during the cooking-pasteurization, also means a lesser mechanical treatment of the meat piece during the process, which will allow to obtain a product with a best appearance, similar to the one obtained through craftsmanship.

On the other hand eliminating said juices, , is essential, mainly for the packed product suitable preservation.

Bearing in mind that after meat product cooking-pasteurization and when opening the wrapping (bag), unavoidable a product surface recontamination arises, after the final repacking a pasteurization or sterilization stage is required for a product correct preservation. In this point, the further product heating once its final packing is achieved, was up to now the most used method to significantly extend the preservation of the cooked-pasteurized products, without requiring to have recourse to other treatments, such as chemical or radiations after said final packing.

For such aim, up to this moment, several equipments were developed which generally include a great volume and high cost, with dilated operative times.

We can mention, namely, the use of autoclaves of nonstop operation. One of said equipments existing on the market includes three columns arranged one after the other for the heating-sterilization-cooling stages. The molds are automatically entered inside containing devices which passes conveyed by conveying means through said columns, the sterilizing medium being a vapour and air mixture, depending on the cases.

Another autoclave of above type includes an horizontally positioned boiler in which the containers enters through a conveying chain and a gate, either or not submitted to a rotary movement, to be pre-heated, sterilized and pre-cooled. Later on, and already outside the boiler, they finish their cooling without pressure. The sterilizing medium is water or a vapour and air mixture.

An alternative equipment includes an oven in which the products are introduced and which, after a certain period of time of heat contribution and further cooling, is unloaded, though this process makes a non-stop work difficult, as it demand loading and unloading operations of the working premise.

As it can be seen, above processes, all of them, mean in addition to a long heating time, also, necessarily, a significant cooling time.

On the other hand, said sterilization or pasteurization stage, in addition to above drawbacks, and mainly due to the long time of process with heat contribution, provokes in a number of cases an impairment of the meat piece surface colour by degradating the meat pigment, modifying therefore the appearance conditions of the end product obtained.

The invention relates to a procedure, which means first, a significant decrease of the process time with respect to the state of the art disclosed, and a guaranty of a long packed product (meat piece) preservation, thanks to an effective elimination of the microbial flora from de product recontaminated area, once the post-cooking-pasteurization stage to eliminate exudate and condition the surface of said meat piece is ended, with an utmost preservation of the organoleptic properties of the product involved.

The operative conditions of the procedure disclosed allows in addition that the plant has a smaller and less complex volume, and makes possible a nonstop treatment which encompasses the products sterilization and final packing under aseptic conditions.

BRIEF SUMMARY OF THE INVENTION

The invention is on the grounds of applying a HTST (high temperature short time) sterilization technique, i.e. it consists in producing a high temperature thermal shock (of at least 100-160 degrees C), of a very short duration, to which the whole product surface is submitted after the re-conditioning stage (meat piece exudate elimination and surface conditioning) after the post-cooking-pasteurization stage, and which is followed by a final vacuum or (controlled) modified atmosphere packing, in aseptic conditions, all of it being achieved in a nonstop process.

The heat exchange process associated to the HTST sterilization techniques because of the nature of the equipment used was only applied up to now to liquids or to liquids which contained small particles. When the size of said particles is over a few mm the effectiveness of the sterilization method is lost as the particle thermal center is not reached, in addition to request complicated product conveying means through the treatment area.

However, in accordance with the principle disclosed in this invention, the HTST technique, has being found applicable and effective for meat pieces. submitting them previously to a cooking-pasteurizing i.e. it can be used in the mentioned re-packing stage, preceding the properly called packing which would be achieved later on in aseptic conditions, because in the mentioned prior reconditioning stage (meat piece exudate elimination and surface conditioning), only a superficial contamination will occur, i.e. limited to the stratum immediately close to the external face of said meat piece. This way, a HTST technique treatment, is useful and feasible, as it fully affects the product external layer, achieving, in addition a much more effective result as for microorganisms impairment and/or growth inhibition thereof, than the one resulting from applying the traditional heat contribution techniques with the meat piece located inside a tight-closed packing, obtaining a self-stable product fit for a longer duration preservation than the provided by said traditional techniques and procedures used and with a minimum organoleptic degradation.

In addition, as the high temperature thermal treatment, according to the HTST technique, only affects the meat piece surface layer or stratum, cooling said piece will occur speedier, allowing to proceed in a nonstop manner to the product final packing, in aseptic conditions.

Therefore, the procedure disclosed consists basically in following steps: <ul id="ul0001" list-style="none"><li>a) meat piece pasteurization by cooking inside rigid or semi rigid molds or containers, advantageously protected by a wrapping means, open or closed, until it reaches a temperature in the thermal center of the meat piece of 65 to 75 Degrees C, and during an interval of time sufficient for a suitable pasteurization of the product which guaranties heating effects (value F <maths id="math0001" num=""><math display="inline"><mrow><msubsup><mrow><mtext>​</mtext></mrow><mrow><mtext>70°C</mtext></mrow><mrow><mtext>10°C</mtext></mrow></msubsup><mtext>)</mtext></mrow></math><img file="EP0506599A2_D0001.tif" /></maths> over 30 measured at the piece thermal center;</li><li>b) withdrawal of the pasteurization meat piece from its wrapping means, exuded fluids elimination and product external surface conditioning;</li><li>c) sterilization of the meat piece surface layer or stratum, submitting it to a thermal shock of high temperature during a very short interval, in accordance with a HTST technique (high temperature short time) operating in room temperature conditions directly in contact with the meat piece surface over 100 ^<u>o</u>C and the time of treatment by piece being under 15 second;</li><li>d) product re-packing in aseptic conditions, steps c) and d) being carried out by an automatic equipment by means of a nonstop process, without organoleptic and nutritious conditions impairment.</li></ul>

With regard to the machine provided to perform steps c) and d) of the procedure according to the invention it is characterized by comprising:    means to introduce, at least, a meat piece, after sustaining above treatments, inside a first station for said piece surface sterilization, said first station including a chamber that can be tight closed;    means for taking, holding in a stable position inside said first station, and to release said meat piece;    means for tight sealing of said chamber of said first station, once the meat piece has been introduced therein, and to open the chamber after a pre-set time required for a meat piece surface sterilization;    means for providing heat inside the inclosure of said first station, in position of tight sealing, until the internal atmosphere reaches an average temperature ranging from 100 to 160 degrees, with an interval of treatment time below 15 seconds;    means to withdraw the sterilized meat piece from inside the chamber of the first treatment chamber, and to transfer said piece to a second station for the wrapping thereof where it is placed in a pre-set position;    means for sequentially positioning tubular containers such as bags, from a storage area thereof, up to a position in said second station in which its inlet remains adjacent and facing the meat piece position in the second station;    means for opening the inlet of said tubular container and keep it open, and to fix, at least two walls of said bag;    means to transfer by pushing moving the meat pieces inside the containers with their inlet open;    means to grip the filled containers, with their inlet still open and to move them, in said conditions up to a third station where it is proceeded to a vacuum sealing thereof; said three stations and the whole of said means remaining located except the meat piece entering means to the first station, inside a wrapping enclosure provided with an ultrafiltrate air impulsion module, constituting a laminar upright flow cabin, to guaranty the asepsis of the atmosphere in which the operation are carried out, and in that said means are synchronized for a sequential cyclic performance of the process different stages;

The above and other objects, advantages and features of the present invention will become more apparent from the following description of certain preferred embodiments thereof.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig.1 is an explanatory diagram of the different steps of the procedure.

Fig.2 is a general perspective view of the machine, without its upright laminar flow wrapping cabin, showing the three stations composing it.

Fig.3, is a top plan view of the machine unit.

Fig.4 is a side elevational view, with partial section showing the supporting floor conveying means to enter and withdraw the meat piece with respect to the first station.

Fig.5 is a top plan view, of part of above conveying means.

Fig.6 is a top plan view showing the means to hold the meat piece inside the chamber of the first station and the means to withdraw said meat piece, and Fig.6A shows a detail of supporting floor of the meat piece applied to the withdrawal from said first station.

Fig.7 is a side elevational view in cross-section of the ring constituting the first station chamber side wall.

Fig.8 shows the driving means for rotating said ring and one part of periphery of the bottom disc, through a cut out of the annular flange of the ring.

Fig.9 is a side elevational view with partial section disclosing the means to move the meat piece supporting grid (half left side) and the chamber sealing cover (half right side) forming the first station.

Fig.10 is a detail at larger scale of the preceding figure showing, namely the means to rotatable support the surrounding ring as well as the tight closing means between the bottom disc and the plate holding the cover. Fig.10A shows another top plan view of the revolving means used to support and guide said surrounding ring.

Figs.11 and 12 are side elevational views of the machine unit taken according to the direction of the arrow A and B of Fig.3, respectively.

Fig.13 is an elevational view taken according to the direction of the arrow C of Fig.3.

Figs.14 and 15 show the means to grip the containers with the meat piece from the first station to transfer them to the third one.

Fig.16 shows the means for lifting the unit of figures 14 and 15.

Figs. 17 and 18 show the mechanism for operating lateral blades and Fig 19 the corresponding mechanism related to central blades to keep the bag open, clamping its inlet edges when placed on the second station in order to facilitate the related meat piece entering inside thereof

Lastly Fig.20 and 21 show the mechanism for driving the clamps to grip the bags with the meat pieces to transfer them from the second station to the third one.

DETAILED DESCRIPTION

Referring to above figures, and namely Fig.2, the machine concerned by the invention comprises essentially three stations: sterilizing station -1-, a bag filling station -2-, and a sealing station -3- for the bags including a meat piece.

At both sides of the first station -1- there exists units to enter the meat piece inside said station, and for withdrawing it, respectively, generically called with the letters E and 0, which essentially comprise a frame -4a-, -4b- and a movable supporting floor -5a-, -5b- formed by a plurality of strips -6a-, -6b- linked to a conveying truck constituted by a transversal joist -7-, side plates -8- supporting wheels -9- which surround horizontal guides -10-, fixed to the frame -4-. Said joist -7- has an inverted U shaped cross-section, and inside such U wheels -11- are arranged, linked to a T-shaped support - 12-which is fixed by one of its ends by a C-shaped part - 13- to a link -14- of a chain -15-, which extends between two coplanar toothed wheels -16- and -17-, one of them driven and the other controlled by a motoreducer -18-. The strips set -6- remains locked, by one of its ends, to the joist -7- and is supported, by its other end on a support - 19- fixed by a strut -20- to the frame -4a-, -4b-, said support including guides -21-.

Said sets E and O remains linked to the central station by rigid locking plates -22- in order to guaranty a suitable aligning of said strips in order to allow them interpenetrating with respect to a grid -23- of strips installed inside the chamber of station -1-.

The set O, has as single difference from the one E that enters the meat piece, in that, as shown in Fig. 6 and detail 6A, the strips -6b- show offset areas -24- to lodge cylinders -25- ending in shafts -26- which are socketed in end notches -27- of each offset, allowing its free rotation -1-, so forming a rotatable floor.

First station -1- comprises a bedframe -28- on which is defined a receptacle including a fixed disc -29- as bottom, with a basin -29a- on its periphery and a circumferential groove -30- close to its edge where a sealing gasket -31- is arranged. The disc -29- is surrounded by a ring -32- of C-shaped section inwardly oriented, rotatable movable, whose annular ribs loosely clasp the periphery of said disc -29- and having a series of equally spaced crosscuts -33-, equivalent to those -29b- existing on mentioned disc -29-, to allow its positioning, said ring resting (see fig. 10 and 10A) on a set of wheels -34a- -34b-, which are mounted on a support -35- integral with the bedframe -28-. Said ring -33- is linked to an hydraulic cylinder -36- with its body locked to the bedframe -28- and its stem linked to the ring -32- external side wall.

Above the bottom -29- there exists a supporting floor for the meat piece, formed by a grid -23- (see Figs. 3,6 and 8) whose bars are locked to two cross sectional profiles -37- which in turn remain linked to both pairs of stems -38- guided by sockets -39- fixed on a basin-shaped centre portion -29a- of the disc -29-. The stems -39- are joined to each other, in pairs, by means of profiles -40- which, in turn, remains linked by a cross sectional profile -41- (see fig. 13) forming an H which remains joined to a stem of a fluidodynamic actuator -42- with an upright stem.

Integral with the bottom -29- of the receptacle there exists three other cross sectional profiles -44- where are arranged U-shaped profile parts -44-, of a low friction coefficient material such as Teflon, acting as a guides for the strips -6a- and -6b- of the entering and extracting planes -5a- and 5-b-.

First station comprises a higher plate -45- which is topped at its center portion by a double-dome-shaped covering part -46-. The plate -45- is integral with two upright stems -47-, which in turn are guided by sets of pulleys -48- mounted on supports -49- integral with joists -50- of the bedframe -28-. The stems -47- are joined by their lower part by a bar -51- which is connected to a second fluidodynamic actuator element -52-.

The plate -45- shows a series of peripherical crosscuts -45a- equivalent to the ones -29b- existing on the periphery of the fixed disc -29-, and on the protruding ribs there is, detachably locked by their two faces, wedge-shaped in circumference segment parts -54- which correspond to wedge-shaped profiles -55- defined on the internal higher and lower faces, of the C-shaped profile of the surrounding ring -32-.

On other side, the means to provide heat inside the chamber of said first station comprise nozzles -56a- and -56b- to supply and suck high temperature and pressure vapour.

Second station (see Fig. 11) comprises a tilting head -57- by means of arms -58- rotatable articulated and driven by an fluidodynamic cylinder -59-, whose head includes an overhanging plane -60- provided with a series of suck pads -61- to grip, at least, two bags -65- each time, from a warehouse -62- of said stacked bags -65-, and for moving them onto an horizontal floor -63-, wherein there exists a transversal slot -64-, associated to vacuum generating means to retain a second face, opposite to the first one, of the bag -65- and blades -66- and -67- to lock the side parts and the lower edge of the bag inlet superposed on the table -63-, which remains coplanar with the supporting floor -5b- of the meat piece withdrawing means.

Tilting head -57- comprises a fluidodynamic actuator -57a- providing a vertical displacement, in order to take the bags -65- from the warehouse, and also has a cylinder -98- to actuate blades -99- in order to hold the upper edge of the bag inlet.

Figs. -17- and -18- show the mechanism to drive the side blades -66- which includes a set of two spindles -68- and -69- each of them ending in toothed wheels -70-, -71- geared to each other and one of them holding a shaft -72- with a driving crank -73- Associated to said spindles and guided by an intermediate guide -74-, parallel to said spindles, are arranged pairs of sliding supports, -75- and -76-, with holes threaded to one of the spindles and passing with respect to the other spindle, related two by two with bars -77- housed in rotating levers -79-, -80- mounted in said sliding supports -75-, -76-. The stem -82- of a fluidodynamic cylinder -81- is articulated to a lug - 78- of said bars -77- and said cylinder is integral with one of the sliding supports, in such a way that when said cylinder acts, a coordinated rotation of the levers -79-, -80- and through it of the lateral blades -66- occurs. The mechanism of spindle allows to suitably position said side parts depending on the width of the bag. The sliding supports -75- hold the blades of one of the sides of the two bags and the supports -76- the two blades of the other side.

On other hand, Fig. 19, shown the means to drive the blades -67- designed to hold the bag lower edge which consist in L-shaped plates locked by one of their ends to a shaft -82- which is rotated by a lever -83- and a pneumatic cylinder -84- one of the L-shaped part planes -67- can be superposed, after a 90-degree rotation on above plane -63-.

In order to transfer the meat pieces from second supporting floor -5b- onto the plane -63-, pushing means are employed consisting in a L-shaped profile -111- with one of its arms parallel and superimposed to the strips - 6b- and rotatable cylinders -25-, and the second arm linked to the stem of a fluodynamic actuator -112-.

The means applied to move the wrapped pieces up to the third station -3- comprise clamps -85- mounted with possibility of lengthwise displacement along guides -86- of an horizontal overhanging arm -87- associated to a column -88- with means for lifting and lowering said column -88- which are shown in fig. 16.

Said lifting means (Fig. 16) comprise an upright hydraulic cylinder -89- at the end of the stem thereof there is arranged a pulley -90- and around it a chain -91- extends, locked by one of its ends to a fixed point -92- and associated by its other end -93- to a support -94- uprightly guided inside a static upright support -95-.

The lengthwise movement of the clamps -85- along the arm -86- is carried out thanks to a fluidodynamic cylinder -100-.

The containers sealing station is of a conventional type and we must only emphasize that when the bag linearly moves with the product, when leaving said bags in the recess, provided with a cover -96- moved by a cylinder -97-, said bags are always left in a pre-set position to make sealing means operative.

Fig. 13 shows the cabin -97- of upright laminar flow which surrounds the set of the three mentioned stations guarantying that all the operations that are carried out sequentially, are achieved in a sterile atmosphere.

Lastly Fig. 20 and 21 describe the mechanism to actuate the clamps -85- comprising pairs of slidable support pieces -101-, -102-, which can lengthwise move along guide rods -103-, -104- and connected through levers -105-, -106- to diametrically opposed points of two rotatable discs -107-, -108-. One of the members of each pair of support pieces is attached to the stem of a fluidodynamic cylinder -109-, -110- integral with a housing of the unit. As indicate the arrows in fig. 21, when one of the slidable support pieces is pushed the other support is also moved, approaching or separating so as to open or close the clamps -85-.

The fluodynamic actuators employed can be hydraulic or pneumatic depending of the performances or the features of the plant.