FR2794936A1 - Continuous production of soft cheese by grinding curds and supplying them to extruder that transports, compresses, kneads, cuts and decompresses them to produce soft cheese - Google Patents

Abstract

Soft cheese is manufactured by grinding curds and introducing the fine particles into an extruder having two co-rotating interlaced screws. The extruder transports, compresses, kneads and cuts the particles, then decompresses them and produces soft cheese at 50 - 60 deg C. These are cut into cylindrical pieces and allowed to cool to room temperature. In the extruder the particles are heated progressively to 80 deg C. Brine and penicillin solution are added as the particles are transported. An Independent claim is included for the equipment for performing as above. Preferred Features: A gas at room temperature, e.g. nitrogen or carbon dioxide including about 5% oxygen, is introduced into the decompression stage of the extruder to develop mycelium in cavities. The extruded cheese are cut at 50 - 60 deg C.

Description

The present invention relates to a method and an installation for continuous preparation of soft cheeses from a curd.

The cheeses are prepared from a raw material which is usually made up of milk and can be classified into several categories which depend on the mode of coagulation of the milk, the nature of the dough, the crust and the dry extract content.

These categories are, for example, fresh, soft, blue or marbled cheeses, cooked or spun.

The manufacture of the cheese by the traditional method consists in separating the constituents of the milk into two parts by effecting a coagulation during which the casein is insolubilized and a dripping during which the whey or whey separates from the curd. The coagulation of the milk by rennet is the most used means and it allows to separate the phospho- paracaseinate of calcium with the fat retained in the curd.

Then the fresh curd thus obtained is molded and salted.

The mold gives the cheese its shape and this operation which is generally mechanized has the disadvantage of being heavy and expensive. In addition, it requires important equipment that must be perfectly clean. In general, the molding operation is an operation that is a big consumer of time, equipment and energy.

The salting operation makes it possible to protect against undesirable micro-organisms and a drainage of the serum as well as an additional dewatering. The salt also has an effect on the taste of the cheese and an influence on the activity of the enzymes during the subsequent refining operation.

Then the cheeses are refined in appropriate salts whose humidity and temperature are controlled and this refining operation allows to give the cheese its aroma and flavor as well as the desired texture to the dough and its typical external appearance.

The different changes in temperature depend on a set of physical and chemical conditions, the most important of which are those which affect the development of microorganisms and the activity of enzymes. The changes that the cheese undergoes also depend on its shape and size. The ratio of surface area to weight is an important characteristic, especially in soft cheeses. The thinner the mirror, the faster and more regular refinement, in the center as at the periphery.

It is an object of the invention to provide a process and an installation which makes it possible to continuously prepare soft cheese moldings without breaking the batch in the soft-dough production line and which also makes it possible to obtain a dough having good properties. organoleptic qualities, while reducing the energy consumption and the different handling operations usually required to produce such a dough.

The subject of the invention is therefore a process for the continuous preparation of soft cheeses from a curd, characterized in that the curd is crushed into fine particles, and the curdled curd is continuously introduced into a machine. co-rotating and co-penetrating two-screw extrusion driven in rotation about parallel axes inside an elongated sheath, - is carried out in the sheath of the extrusion machine at least two stages of transport, compressing, mixing and shearing of the curd followed by a decompression step, the curd is heated during these steps to gradually bring it from ambient temperature to about 80 ° C. inside the sheath of the extrusion machine, during the first stage of transport, saturated brine, - is injected inside the sheath of the extrusion machine, during a said trans stages Port, a penicillium solution, is extruded and shaped at the output of the extrusion machine the soft paste obtained at a temperature between 50 and 65 C, the soft dough is cut into lengths of length determined, it is allowed to gradually cool this soft dough to room temperature, and refining said soft dough.

According to another characteristic of the invention, the curd is baked at a temperature of between 50 and 60 ° C. before grinding.

According to yet another characteristic of the invention, a gas is injected inside the sheath at the beginning of the decompression stage at room temperature to create cavities in the soft dough which promote the development of the mycelium in these cells. cavities.

The invention also relates to an installation of continuous preparation of soft cheeses from a curd, characterized in that it comprises - means for grinding the curd into fines by particles, - means of continuous introduction of the milled curd into a feed port provided in an elongated sheath of a co-rotating and co-penetrating twin screw extruder driven in rotation about parallel axes, said screws determining at least two zones for transporting, compressing, kneading and waxing the curd followed by a decompression zone and the sleeve comprising means for heating the curd to gradually bring it from ambient temperature to approximately 80 ° C .; injection means inside the furnace of the extrusion machine, in the first transport zone, saturated brine, - injection means inside the furnace reau of the extrusion machine, in one of said transport zones, a solution of penicillium, - a die for extruding and shaping the soft paste at the outlet of the extrusion machine at a temperature between 50 and 65 ° C, and means for cutting the soft dough into sections of determined length.

According to other features of the invention - the plant comprises, upstream of the grinding means, means for cooking the curd at a temperature of between 50 and 60 ° C., the installation comprises means for injecting inside the sheath at the beginning of the decompression stage, a gas at room temperature to create cavities in the soft dough that favor the development of the mycium lium in these cavities, - the first zone of the screws of the machine ex trusion comprises a first transport section provided with nets with wide pitch and at the beginning of which opens the feed port, a second section of compression and my lapping with tight pitch and a third section of shears provided with eccentric mixing discs, - the second zone of the screws of the extrusion machine comprises a first conveying section provided with threads with a tightened pitch, a second compression section and my lapping with a very tight pitch é and a third section of eclésement equipped with eccentric mixing discs.

Other features and advantages of the invention will become apparent from the description which follows and with reference to the accompanying drawings, in which - Figure 1 is a schematic view of an installation of continuous preparation of cheese pastes According to the invention, FIG. 2 is a sectional view in a vertical plane passing through the axis of a screw of an extrusion machine of the preparation plant according to the invention. FIG. 3 is a cross-sectional view of the extrusion machine; FIG. 4 is a sectional view along the line 4.4 of FIG.

The plant shown diagrammatically in FIG. 1 is intended for the continuous preparation of soft cheese from a curd.

In a first step, the constituents of the milk are separated into two parts, for example by carrying out a coagulation during which the casein is insolubilized and a dripping during which the whey or whey separates from the curd.

As shown in Figure 1, the curd is first milled for example in a knife mill 1 in fine particles of about 1 centimeter in diameter.

In the case of a cooked cheese, the curd is, before grinding, cooked at a temperature between 50 and 60 C.

The crushed curd is then introduced by a volumetric meter 2 at a rate of, for example, 30 kg per hour in an extrusion machine generally designated 10.

As shown in FIGS. 2 and 3, the extrusion machine 10 is of the type with two co-rotating and co-penetrating screws and comprises two screws 11 and 12 driven in rotation about their axes by a motor and a reduction mechanism. , not shown, inside an allon gaged enclosure forming a sheath 13 which envelops them.

The screws 11 and 12 are provided with helical threads which mesh with each other and the inner wall of the sheath 13 forms two intersecting cylindrical lobes, respectively 11a and 12a, with an inside diameter slightly greater than the outside diameter of the screw threads. B> it </ B> and 12. These threads are nested one in the other and the two screws 11 and 12 are driven at the same speed of rotation and in the same direction so that the two screws are identical , the threads being simply offset with respect to each other.

As shown in Figure 4, the screws 11 and 12 are advantageously constituted by splined shafts, respectively 14 and 15, on which are stacked the screw sections.

The internal bore of these screw sections is provided with grooves corresponding to that of the shaft and the outer portion is provided with helical threads whose pitch differs according to the section considered for the treatment and transport of the curd introduced at the end. upstream of the sleeve 13 of the extrusion machine 10.

There can thus be a large number of sections to vary the pitch, the depth, the number of nets and the length of each zone.

Thus, the extrusion machine 10 comprises continuously, from upstream to downstream in the direction of transport, at least two treatment zones.

In the exemplary embodiment shown in the figures, the extrusion machine 10 comprises a first zone A for conveying, compressing, kneading and grinding the curd, a second zone B for conveying, compressing, kneading and shear followed by a decompression zone C and a zone D of evacuation of the soft paste thus obtained.

In the first zone A, the sheath 13 is pierced, at its upstream end with respect to the flow direction of the material, with a supply orifice 16 connected to the outlet of the metering device 3 via a pipe 17.

In the first zone A, the threads of the screws 11 and 12 determine three sections, respectively A1, A2 and A3.

In the first section A1, the screws 11 and 12 are provided with threads 18 with a wide pitch to ensure the transport of the milled curd introduced by the orifice 16 which opens widely over the two screws 11 and 12 and in order to leaving said milled curd in the nets.

Thus, the fine crushed curd particles are transported downstream of the extrusion machine to the second section A2.

Substantially at the end of the first section A1 the sleeve 13 is pierced with an orifice 19 which is connected to injection means within this sleeve 13 of a saturated brine in order to effect the salting of the curd.

The injection means for the saturated brine consist, for example, of a peristaltic pump 20 (FIG. 1) whose discharge orifice is connected to the injection port 19 via a pipe 21.

By way of example, the brine used is prepared from a saturated salt solution at a concentration of 300 g of salt per liter of water. The curd is salted at a rate of 1.5kg of salt per 100kg of curd and the amount of brine is therefore 5.7kg per 100kg of curd.

The effects of salting are numerous and in particular make it possible to protect against undesirable microorganisms and a drainage of the serum as well as additional drainage due to the hygroscopicity of the salt or the high osmotic pressure of the brines.

Salting also has an effect on the taste of the cheese and influences the activity of the enzymes.

According to a first embodiment, a penicillium solution is injected inside the sleeve 13 of the extrusion machine 10 at the same time as the saturated brine. For this purpose, the pipe 21 is connected to a pipe 22 which is itself connected to the discharge port of a peristaltic pump 23 for injecting through the orifice 19 said penicilium solution in predetermined amounts.

Following the section A1, the zone A comprises a second section A2 in which the screws 11 and 12 comprise threads 24 with a pitch constricted so as to make a mixture of the curd particles with the brine and optionally the penicillium. To this mixture of these different products is added a compression of the mixture.

The mixture then passes into the third shear section A3.

In the third section A3, the screws 11 and 12 are provided with mixing discs 24 and eccentrically, as shown in FIG. 4. These mixing discs 24 allow controlled downstream passage of the mixture with a rolling and shearing effect. between these discs 24 and the inner wall of the sleeve 13.

During its transfer in the section A1 of the first zone A, the curd is gradually heated to a temperature of the order of 25 C.

The second zone B formed by the screws 11 and 12 of the extrusion machine 10 is also composed of three sections, a first transport section B1, a second compression and mixing section B2 and a third section B3 of shear.

As shown in Figures 2 and 3, the screws 11 and 12 are, in the first section B1, provided with threads 26 with a constricted pitch, identical to the threads 24 of the second section A2 of the first zone A.

Following the first section B1, the screws 11 and 12 are, in the second compression section B2 and my laxage, provided with nets 27 with a very narrow pitch.

Following the second section B2, the screws 11 and 12 are provided with kneading disks 28 which determine the third shear section B3 of the second zone B. The kneading disks 28 allow a controlled downstream passage of the material with a shearing effect between the discs 28 and the inner wall of the sheath 13.

In the decompression zone C, the screws 11 and 12 are equipped with threads 29 with a tightened pitch identical to the threads 24 and 26 respectively of the sections A2 and Bi desdits screws 11 and 12. During its passage successively in the zones A3 , B and C, the material is gradually heated to a temperature of about 80 C.

To gradually raise the temperature of the curd from room temperature to this temperature of 80 C, the sleeve 13 of the extrusion machine 10 is equipped with heating means.

As represented in FIGS. 2 and 3, the heating means consist of a first circuit 30 for circulating a heat transfer fluid, formed in the sleeve 13 and extending over the section A1 of the first zone A to gradually heat the curdled at a temperature of the order of 25 C and by a second circuit 31 for circulating a coolant, formed in the sleeve 13 and extending over the sections A2, B1, B2 and B3 so as to bring the prepared pulp in the extrusion machine 10 at a temperature of about 80 C.

These heating means may also be constituted by one or more electric heating means, for example by induction.

At the outlet of zone C, the soft paste thus prepared in the extrusion machine 10 is extruded by a die 32 at a temperature of between 50 and 60 ° C. and in the form of a continuous bead 3 deposited for example on A conveyor belt 4. The die 32 has at least one orifice 32a whose section corresponds to the section of the flange to be obtained.

The roll 3 of soft paste thus formed at the outlet of the extrusion machine 10 is cut into sections 5 of determined length by a suitable device 6 such as for example a knife device 6.

At the outlet of the extrusion machine 10 and after the cutting of the soft dough into sections, the cheese is formed by filling molds of corresponding shape to the shape of the cheese to be obtained.

The molds thus filled with soft dough are transported to a cooling room 7 where they are gradually cooled to room temperature. The cooling is for example carried out first at room temperature, then at 4 C. The cheeses can then be stored in an enclosure for 12 hours at 4 C.

After cooling, the cheeses are conveyed into humidity and temperature controlled enclosures 8 so as to carry out the ripening operation and obtain a soft cheese with a rind of flowers.

According to a variant, the penicillium solution can be injected inside the sleeve 13 of the extrusion machine 10 directly with the curd at the inlet of said extrusion machine 10 through the orifice 16.

According to another variant, the penicillium solution can be injected inside the sheath 13 of the extrusion machine 10 at the beginning of the second zone B and more precisely at the section B1 of the screws 11 and 12. in this case, the sheath 13 of the extrusion machine 10 is pierced by an injection orifice, not shown, opening inside this sheath 13 at the section Bl of the screws 11 and 12.

In the case of the manufacture of a blue or marbled paste, a gas at ambient temperature such as for example nitrogen or carbon dioxide is injected into the sheath 13 of the extrusion machine 10.

For this, the installation is equipped with means for injecting this gas at the beginning of the decompression zone C determined by the screws 11 and 12.

The gas injection means are constituted, as shown in dashed lines in FIG. 1, by a peristaltic pump 33, the discharge orifice of which is connected by a pipe 34 to an orifice 35 formed in the sleeve 13 of the machine. extrusion 10 at section C.

The injection of this gas into the soft dough is intended to create cavities to promote the development of mycelium within these cavities to obtain a blue paste or marbled. The gas thus injected into the curd preferably contains a level of approximately 5% oxygen. It is possible to use, for example, a mixture of 95/5 of nitrogen and oxygen.

For example, the extrusion machine 10 has the configuration shown in the table below

ZONES <SEP> A1 <SEP> A2 <SEP> A3 <SEP> B1 <SEP> B2 <SEP> B3 <SEP> C
<tb> Length <SEP> 500 <SEP> 50 <SEP> 100 <SEP> 250 <SEP> 50
<tb>
<tb> screw <SEP> (mm)
<tb> No <SEP> of <SEP> 50 <SEP> 25 <SEP> DM <SEP> 25 <SEP> 15 <SEP> DM <SEP> 25
<tb> screw In the preparation plant according to the invention, the extrusion machine is used as a chemical reactor. By way of example, the preparation time of the soft dough in the extrusion machine is of the order of thirty seconds to one minute.

Furthermore, the pitch and the length of the screw sections can be adapted to the type of soft dough to obtain. This extrusion machine makes it possible to obtain protein denaturation under the action of heat, intense shear and high pressures as well as orientation of the denatured protein chains by means of a suitable mechanical work.

Indeed, the proteins undergo a denaturation due to the thermal and mechanical actions and acquire gelling and emulsifying properties, allowing to structure the protein network around fat globules, which are even smaller than the shear rate is high.

The structure of the soft dough obtained is stabilized thanks in particular to a perfectly controlled cooling.

 The process and the installation according to the invention thus make it possible to refine a textured dairy curd by cooking-extrusion, to produce a soft cheese with a flowery rind having good organoleptic qualities.

Claims (15)

1. Process for the continuous preparation of soft cheeses from a curd, characterized in that the curd is crushed into fine particles, the curdled curd is continuously introduced into an extrusion machine (10). two screws (11) (12) co-rotating and co-penetrating, driven in rotation about parallel axes inside an elongated sheath (13), - is carried out in the sheath (13) of the at least two stages of conveying, compressing, kneading and shearing the curd following a decompression step, the curd is heated during these steps to bring it gradually from at ambient temperature up to about 80 ° C., the saturated brine is injected into the inside of the sheath (13) of the extrusion machine (10) during the first transport step; inside the sleeve (13) of the extrusion machine (10), during one of said transport, a solution of penicillium, is extruded and shaped at the outlet of the extrusion machine (10) the soft paste obtained at a temperature between 50 and 60 C, - the soft dough is cut in sections (5) of determined length, it is allowed to gradually cool this soft paste to room temperature, and the sections of soft dough are refined. 2. Method according to claim 1, characterized in that prior to grinding, the curd is baked at a temperature between 50 and 60 C. 3. Method according to claim 1, characterized in that the inside of the sheath (13) is injected at the beginning of the decompression step, a gas at room temperature to create in the soft dough cavities favoring the development of mycelium in these cavities. 4. Method according to claim 3, characterized in that the gas is constituted by nitrogen or carob gas. 5. Method according to claim 3, characterized in that the gas contains about 5% oxygen. 6. Installation for continuous preparation of soft cheeses from a curd, characterized in that it comprises - means (1) for grinding the curd into fine particles, - means (2) of introduction into continuous operation of the milled curd in a feed port (16) in an elongated sheath (13) of an extruder machine (10) with co-rotating and co-penetrating two screws (11, 12), strokes in rotation about parallel axes, said screws (11, 12) determining at least two areas of transport, compression, kneading and shear curd following a decompression zone and the sheath comprising means (30). 31) for heating the curd to gradually bring it from ambient temperature to approximately 80 ° C., injection means (20) inside the sleeve (13) of the extrusion machine (10). in the first transport zone, a saturated brine, - injection means (23) the inside of the sheath (13) of the extrusion machine (10), in one of the said transport zones, with a solution of penicillium, - a die (32) for extruding and shaping the soft paste at the outlet of the extrusion machine at a temperature of between 50 and 60 ° C., and means (6) for cutting the soft dough into sections (5) of determined length. 7. Installation according to claim 6, charac terized in that it comprises, upstream of the grinding means (1), means for cooking the curd at a temperature between 50 and 60 C. 8. Installation according to claim 6, charac terized in that it comprises means (33) for injection into the sleeve (13), at the beginning of the decompression step, a gas at the room temperature to create in the soft dough cavities favoring the development of mycelium in these cavities. 9. Installation according to claim 8, charac terized in that the gas consists of nitrogen or carbon dioxide. 10. Installation according to claim 8, char acterized in that the gas contains about 5% oxygen. 11. Installation according to claim 6, char acterized in that the first zone of the screws (11, 12) of the extrusion machine (10) comprises - a first section (A1) carrying nets (18) with steps and at the beginning of which opens the feed port (16), - a second section (A2) of compression and kneading provided with threads (24) with a tightened pitch, - and a third section (A3) of shear equipped with mixing discs (25) eccentric. 12. Installation according to claim 6 or 11, characterized in that the injection means of the saturated brine are formed by a peristaltic pump (20) connected to an injection port (19) in the sleeve (13) to the end of the first section (A1) of the first zone of said screws (11, 12). 13. Installation according to claim 6, char acterized in that the second zone of the screws (11, 12) of the extrusion machine (10) comprises. a first conveying section (B1) provided with threads (26) with a constricted pitch, a second section (B2) for compression and kneading provided with threads (27) with a very narrow pitch, and a third section (B3). shearing device with eccentric kneading disks (28). 14. Installation according to any one of claims 6 or 11 to 12, characterized in that the injection means of the penicillium solution are formed by a peristaltic pump (23) connected to the injection port (19). ) formed in the sheath at the end of the first section (Ai) of the first zone of the screws (11, 12) or an injection orifice formed in the sheath (13) at the end of the first section (B1) of transport of the second zone of said screws (11, 12) or the feed port (16) of the curd. 15. Installation according to claim 6, char acterized in that the screws (11, 12) of the extrusion machine (10) are formed in the zone (C) of decompression, by threads (29) step tightened.