Method for the preparation of cheeses and device implementing this method

The subject of the present invention is a process for preparing cheese and an apparatus for carrying out this process.

Cheese making has been around for a long time and is made from the milk of cows, goats, sheep, mares and other farm animals. According to the usual practice in the matter, the milk is heated to a temperature of the order of 30 ° C to 35 ° C, which corresponds to that of the body of the animal then it is coagulated with rennet, which consists of extracts of stomachs, cut up and macerated, of veal, kid or lamb; the action of this rennet, which contains chymosin, allows the milk to coagulate.

The coagulation or curdling of milk results in the formation of a solid phase, called the curd, and that of a liquid phase, called serum or whey or whey.

The extraction of whey from the solid phase, which is more or less slow, is called syneresis of the coagulum.

The coagulate or curd obtained is generally cut into pieces to allow better extraction of the whey. These pieces of curd are most often of predefined size according to the type of cheese desired and subjected to pressure to extract the serum contained in the coagulum after their introduction into a perforated mold of determined dimensions.

The mussels are most often turned over several times to complete the extraction of the remaining whey and generally kept under pressure.

After demoulding, the products are salted with dry salt or brine, wiped and subjected, most of the time, to a maturation or refining stage, during which they are turned over numerous times.

They can also be subjected to bacterial action or to molds, internal or external, before maturation, to make the proteins and lipids contained in the cheese digestible and to inhibit the development of bacteria harmful to human consumption or to develop tastes or tastes. specific colors.

Over time, manufacturing techniques have improved, in particular by improving better controlled rennets or the use of acidifying lactic starters causing the coagulation of the milk, on the one hand, and, on the other hand, by the use of strains of ferments. well isolated, which can be added at the same time as the rennet or before or during the ripening step.

By way of reference, one can refer to the work entitled "Les Fromages" by Robert J. COURTINE, published by Larousse in 1973-1987, in which the various cheeses are classified according to their method of manufacture into fresh cheeses and ripened cheeses. .

Among the fresh cheeses, a distinction is made between those with slow coagulation which can be salted, such as Demi-Sel or fresh Gournay, or unsalted, such as PetitsSuisses, Fontainebleau or Fresh Neufchâtel, and those with rapid coagulation such as fromage à the magpie.

Among the ripened cheeses, a distinction is made between those with spontaneous draining or accelerated draining.

The former include cheeses with slow coagulation and external mold such as Brie, Neufchâtel, Gournay and Saint-Marcellin and cheeses with rapid coagulation, external mold, such as Camembert or Coulommiers, or with different rinds. natural, such as goat cheese, Langres, Bourguignon, Epoisses, Vendôme or Olivet; they also include other cheeses obtained by cutting with external mold, such as Carré de l'Est, Maroilles or Pont-l'Evêque farmer, or internal, such as Roquefort, Gorgonzola and Bleu d'Auvergne or with crust, such as Münster, Pont l'Evêque dairy, Livarot and Géromé.

The second include cheeses obtained by cutting and brewing, with internal mold like Fourme d'Ambert or rind like Bel Paese or Tilsit, and possibly subjected to pressure, with external mold, like Tome de Savoie or SaintNectaire, or with crust, like Port Salut, Saint Paulin, Holland and Reblochon; they may also have undergone an additional grinding operation, such as Cheddar, Chester, Cantal or Laguiole or have undergone cooking such as Emmental, Gruyère or Comté.

However, whatever the ripening technique used, all these manufacturing processes require essential manual operations, in particular for pressed cheeses with divided curds and accelerated draining, which require a significant amount of labor, the cost of which weighs on the production. economic exploitation of this type of cheese, as the book by André Eck, entitled "Le Fromage" and published by Lavoisier in 1984 clearly indicates. In addition, the molding operations require significant investments in perforated metal molds, the maintenance, size and conditions of hygienic use of which also entail significant expenditure.

The object of the present invention is to remedy these drawbacks by proposing a process for making cheese by curdling the milk, separating the whey, forming blocks and ripening, characterized in that the cheese is formed into blocks. by introducing the curdled milk under pressure into a casing of suitable size for draining and molding, then cutting the casing filled with curdled milk and drained into sections whose thickness depends on the desired height of the finished cheese.

It also relates to an apparatus for the implementation of this method which is characterized by a vacuum pump for the introduction under controlled pressure of the curdled milk inside the casing, said casing being preferably introduced on a tube of '' embossing opening inside the casing for filling and fitted with a whey evacuation system.

The use of a casing, which can be of cellulosic material, of plastic or of collagen, for shaping block cheeses makes it possible to replace the individual metal molds of conventional processes with a single flexible mold for a series. of individual cheeses.

In addition, the handling of casings filled with curd is facilitated, their size is much less than that of individual molded cheeses and their cutting, like slices of sausage, has the advantage of being easy and of keeping part of the casing in each. ripening cheese, which serves as a mold during final maturation and maintains the shape of the finished individual cheese.

It will be noted that the first stages of preparation of a cheese such as the coagulation of the milk by the addition of rennet and / or acid, the shredding by mechanical stirring with reduction of the size of the particles of the coagulum and a draining of the curd in the brewing tank by drawing off the serum are not modified in the process according to the invention.

On the other hand, the following steps of additional draining, of molding in perforated molds to promote the evacuation of the serum, of placing in press or not with turning of the molds, of demoulding, of salting with turning of the products and finally of maturation or d Refining with turning of the products are all profoundly modified, or even eliminated, in the process according to the invention.

Indeed, the step of complementary draining of the curdled milk is usually done in a cloth, by ultrafiltration or centrifugation or any other means of separating a solid phase from a liquid phase; in the context of the invention, the curdled milk is pumped back under pressure in a casing, which makes it possible to express the curd as a result of the back pressure of the casing and to evacuate the serum which can be sucked close to the 'mouth of the tube for introducing the curdled milk into the casing and / or expressed through the walls of the casing, in particular if these are permeable or even perforated.

The traditional step of manual molding of the curdled milk by placing in a mold, perforated or not, is completely eliminated with the process according to the invention, since the curdled milk is molded directly into the casing. This modification allows an appreciable gain in productivity and size and, above all, avoids expensive cleaning and maintenance of the molds. In fact, with the conventional use of metal molds, the problem of cleanliness is crucial and, particularly difficult for perforated molds, which are preferably used because the rate of evacuation of the serum influences the physicochemical and microbiological properties of the paste. It should be noted that a mold of rigid material and preferably perforated to allow the evacuation of the serum, is expensive and that the possibility of doing without according to the method of the invention represents a particularly appreciable improvement on the economic level. .

On the other hand, the usual step of placing the molds in a press or not and of turning the molds in conventional cheese-making processes is no longer necessary in the process according to the invention.

In fact, until now it was considered imperative to turn the molds over in order to prevent their perforations from being blocked by the curd and thus causing a risk of non-evacuation of the serum. In addition, the stagnation of the serum around the cheese promotes the germination and proliferation of harmful fungal flora. And, during this stage, the sensitivity of the curd to open water is very high, and there is a risk of rapid growth of harmful bacteria and other unwanted germs. On the contrary, in the process forming the subject of the present invention, the product being placed in a very solid hose, perforated if necessary, the hose can be put under constant tension, for example using a jack, by pulling on one of its ends, which causes the serum to be rejected out of the casing through the perforations if there are any.

It would be the same if the sausages filled with curdled milk were put in a shape, of great length, on which one would apply a homogeneous pressure over the entire length.

In the case of an unperforated hose, some of the liquid may evaporate through the walls of the hose, because the latter is permeable to water vapor. It will be noted that during this operation, any turning of the products is unnecessary, the casings being able, for example, to be suspended like sausages.

Instead of the conventional demolding step, the method according to the invention comprises cutting the casing of great length and of adequate size containing the curd into slices of the desired thickness, using tools commonly used in the process. food industry, such as a slicer used in salting or baking. This cutting operation can easily be done automatically.

Cheese products produced according to the previous processes were demolded and treated with salt or brine and generally inoculated with a specific microorganism, then turned over several times, to avoid sagging of the product and rounding of its walls. These different operations are obviously manual. To avoid these frequent turning over of each individual cheese, certain “old-style” cheeses were often surrounded by leaves of beech, bark or spruce. In the context of the process according to the invention, the products are put in brine or salted and inoculated, as before, but it is no longer necessary to carry out frequent turning because the section of casing firmly maintains the walls of the product and prevents their sagging. Turnovers are therefore less frequent, or even unnecessary.

Finally, the numerous turn-ups of the products during the last maturation step in the conventional cheese-making processes become less essential in the process according to the invention because, when a permeable casing is used, for example a cellulose casing, reinforced with cellulose fibers, cheese desiccation is the same on both sides and on the side walls. Such a phenomenon is well known in salting for the manufacture of dry sausage. In addition, if one inoculates, for example, with enzymes of cellulolitic type, the cellulose casing section is gradually transformed into carbohydrates and disappears by enzymatic digestion, before the end of the ripening phase. If we use a casing of large casings commonly impermeable, we limit the crust that forms on the side walls of the products. This crust, which represents a loss for the consumer, sometimes requires brushing operations before marketing. The absence of a rind is therefore an advantage and can lead to the creation of new varieties of cheese. Insofar as the section of casing remains on the finished product, it can be used for commercial purposes by coloring, printing or personalizing the products offered for sale.

The method according to the invention makes use of lengths, such as they are used in charcuterie in pleated form for the manufacture of hams, sausages, mortadellas and others. The casings can be in particular made of cellulosic material, optionally reinforced by fibers and more particularly natural fibers, nonwoven, paper or textile. The casings can also be made of plastic, in particular chosen from polymers and copolymers of ethylene, propylene, vinyl chloride, vinylidene chloride, vinyl acetate, polyesters and polyamides. The casing may be made of cellulosic material, in particular of reinforced cellulosic material and present, on one of its faces, a coating impermeable to water and to oxygen. It can also be formed by a collagenic material, in particular reinforced with fibers, a textile support or paper.

It is particularly advantageous to use a cellulosic material for the casing, because it can be manufactured with different porosities depending on the cheese material with which it is brought into contact, to form a barrier to fats and microorganisms, while allowing passage. water vapor.

Regardless of its chemical structure and its dimensions, the casing is preferably perforated with holes having a diameter of between 1/10 th and 5 mm, or more particularly between 4/10 and 8/10 of a mm, at a rate of at least one hole, and more particularly at least four holes, for 10 cm² surface area of ​​the casing.

The apparatus according to the invention is illustrated in a particular implementation in the two attached figures which represent an embossing tube (1), supplied at its left end with curdled milk under pressure by a pump (2) and opening at its right end into a hose (3).

The hose is generally in the form of a flat or pleated hose (Figure 1) or pleated on a hollow mandrel (Figure 2, reference 4), which can be threaded outside the embossing tube.

After introduction of the hose on the embossing tube (1), the hose is partially unwound beyond the mouth (5) of the tube and its right end closed by a clip.

For example, for a pleated hose (3) on a hollow mandrel (4), a ring (6) which simultaneously controls the partial tightness and the braking of the hose is installed. In the case of a flat or pleated hose (3) without a hollow mandrel, it is possible to have one or more rings, one of which (10) has a function of braking the hose and another (6) allows the controlled evacuation of the whey backwards.

The embossing tube (1) is fitted with a device for evacuating the whey under vacuum, against the flow direction of the curdled milk delivered by the pump.

The whey vacuum evacuation device may consist of perforations (7) made through the walls of the mouth of the embossing tube and a pipe (8) connecting the outlets of all of these perforations (7 ) and connected to a collection chamber (9) under vacuum.

Thanks to this device, when the pump delivers the curdled milk under pressure into the hose, which inflates as it fills, the hose back pressure partly pushes the whey between the brake ring (6 ) and the mouth (5) and the whey thus discharged is evacuated by suction through the perforations (7) and the pipe (8) towards the collection chamber (9) put under vacuum, where it is collected.

A feature of the apparatus according to the invention consists of the interposition of a diaphragm (11) at the inlet of the embossing tube (1), requiring a very high pressure in the pump and allowing superior extraction of the whey. .

The invention will now be illustrated by a particular implementation.

100 liters of raw cow's milk, not skimmed, from the previous night's milking, refrigerated at + 10 ° C, at pH 6.5, were introduced into a pot with a capacity of 150 liters, thermostatically controlled at +35 ° C, where they were reheated.

At a temperature of 35 ° C., 60 ml of rennet, containing 500 mg / l of chymosin, manufactured by the French Pharmaceutical Cooperative of Melun, 77000, were added.

The resulting mixture was stirred manually for 1 minute.

After 1 hour, the coagulum was cut with a knife then stirred and allowed to settle.

85.73 kg of whey were thus evacuated and 22.8 kg of curd collected, for a mass of 108.53 kg of raw milk, used at the start.

These 22.8 kg of curd were introduced by a HANDTMANN VF20 pump into an embossing tube, consisting of two concentric tubes, one with a diameter of 38.8 mm having a thickness of 1.5 mm and the other of 52 mm having a thickness of 1.5 mm. An evacuation system connected to a vacuum pump included a collection chamber communicating with the outer tube near its base and having 40 holes of 2 mm in diameter, arranged symmetrically on a circumference 26 mm away from the mouth of the pump. tube.

The embossing tube was equipped with a stick of pleated casing in cellulosic material, reinforced with a nonwoven, known under the trade name FIBROUS 95 SL SHIRMATIC 403, with a length, in the deployed state, of 45 meters, perforated at the rate of 0.9 holes 6/10 mm in diameter per cm² surface area of ​​the hose (9 holes for 10 cm²).

The hose filling device also included a braking and sealing ring with an internal diameter of 53.5 mm and a width of 6 mm and a double clipper POLYCLIP FCAS 3.451, equipped with clips 1812-5-2.5 LR .

The 22.8 kg of curd was forced by the pump into the perforated FIBROUS hose, which was inflated to a caliber 102-103 mm in diameter. 19.08 kg of curds were recovered in the form of three sausages; 3.22 kg of whey were recovered in the pump suction circuit and 0.50 kg of whey in the vacuum evacuation system connected to the holes placed near the mouth of the embossing tube, i.e. a yield of 83.7%.

The three sausages constituting the products obtained were suspended under tension in a refrigerator. Additional drainage of the whey was carried out and, after 92 hours, a 10.9 kg sausage weighed only 8.51 kg, ie a yield of 78.1%.

The sausages thus obtained could be sliced ​​with a knife, without problem, into slices 4 cm thick and these were stored in the refrigerator, flat, for refining.

It was found that the products kept their cylindrical shape well and that the cheese dried equally well on the top and bottom slices as well as on the side walls.

The material balance is summarized in the table below10

<td colspan="3">Painting</td>

<td>Materials</td><td>Weight in Kg</td><td>either %</td>

<td>Raw milk</td><td> 108,53</td><td>Base 100</td>

<td>Drained whey</td><td> 85,73</td><td> 79</td>

<td>Quail</td><td> 22,8</td><td> 21</td>

<td>Evacuated whey</td><td></td><td></td>

<td>. embossing</td><td> 3,72</td><td></td>

<td>. after 92 hours</td><td> 2,39</td><td></td>

<td>Total of</td><td></td><td></td>

<td>whey evacuated</td><td> 91,84</td><td> 84,6</td>

<td>Final curd</td><td></td><td> 15,4</td>

It will be noted that the method and the apparatus according to the present invention can be improved: thus, if the pump has a compression zone, the extraction of the whey can be done by the vacuum system with which it is equipped.

It is also possible to adjust the evacuation of the whey during embossing by playing on a suitable set of the single braking ring with the mouth of the embossing tube so that the ring also ensures the seal on said tube.

Finally, it will be noted that the casing may or may not be perforated and used as it is without prior soaking in water to be moistened, so as to develop a significant back pressure promoting the expression of the whey, when the casing is filled with the curdled milk, by modifying in particular the adjustment of the braking ring on the embossing tube.

During the additional draining after filling the casings with curdled milk in the form of sausages, it is possible to readjust their shape, to compensate for the loss of volume caused by the draining, for example by traction applied to one. or at both ends of the sausages and / or by pressure applied, in a homogeneous manner, over the entire length of the sausages.

If a non-cylindrical shape is desired, the sausages can be shaped in molds of great length, during the additional step.

drip