Method for producing stretched-CURD based cheeses

Abstract

The present invention concerns a method and a plant for producing stretched-curd based cheeses, such as for example mozzarella and suchlike. The method and plant provide skimming of the milk, optionally de-bacterization of the skimmed milk, demineralization, concentration of the skimmed milk, coagulation of the concentrated milk, stretching of the coagulated milk, shaping and packaging of the cheese.

Description

[0001] “METHOD FOR PRODUCING STRETCHED-CURD BASED CHEESES”

[0002]

[0003] FIELD OF THE INVENTION

[0004] The present invention concerns a method for producing stretched-curd based cheeses. In particular, the invention concerns a method for producing mozzarella type cheeses and suchlike.

[0005] BACKGROUND OF THE INVENTION

[0006] Industrial processes for the production of stretched-curd based cheeses, such as mozzarella for example, are known.

[0007] A known method provides to standardize an amount of skimmed milk, that is, adjust the concentration of fats and / or proteins, demineralize an amount of skimmed milk, make it coagulate, concentrate the curd obtained again, allowing it to drain, and then stretch it. The draining step serves to remove a part of unwanted proteins from the final cheese, and also to concentrate the composition thereof. The proteins thus separated can be recovered for use in other preparations.

[0008] The step of demineralizing the skimmed milk, during which part of the calcium present in the milk is removed in a controlled manner, occurs by adding an acid, usually citric acid, and is directly followed by the milk coagulation step.

[0009] After the curd stretching step, there are provided steps of shaping and cooling the curd, then followed by the packaging of the cheese thus obtained.

[0010] A disadvantage of known methods is that the demineralization step is very delicate to perform, due to the protein concentrations in the milk. Demineralization is a key step in the production of stretched-curd based cheeses, since the calcium content in milk directly affects the possibility of stretching and shaping the cheese. Another disadvantage of known methods is that they require the use of bulky machinery and plants that take up a large floor space. This is due, among other reasons, to the fact that the machines are not integrated into a single line.

[0011] Another disadvantage of known methods is that the coagulation, draining, and cooling steps result in a loss of dry substances that adversely affect production yields.

[0012] Furthermore, the draining step is problematic because, in addition to leading to a significant loss of dry substances, it can be a point of contamination and development of unwanted microorganisms.There is therefore the need to perfect a method for producing stretched-curd based cheeses and a corresponding plant that can overcome at least one of the disadvantages of the state of the art.

[0013] In particular, one purpose of the present invention is to optimize production yields by limiting losses of dry substances and maximizing the recovery of fatty and protein substances.

[0014] Another purpose of the present invention is to develop a method and provide a plant for producing stretched-curd based cheeses that allow to perform the subsequent steps in-line.

[0015] Another purpose of the present invention is to develop a method for producing stretched-curd based cheeses that allows to obtain stretched-curd based cheeses with optimized and / or even superior sensory, organoleptic, and / or nutritional properties compared to the known traditional processes described above.

[0016] The Applicant has devised, tested and embodied the present invention to overcome the shortcomings of the state of the art and to obtain these and other purposes and advantages.

[0017] SUMMARY OF THE INVENTION

[0018] The present invention is set forth and characterized in the independent claims. The dependent claims describe other characteristics of the present invention or variants to the main inventive idea.

[0019] In accordance with the above purposes and to solve the technical problem described above in a new and original way, also achieving considerable advantages compared to the state of the prior art, a method according to the present invention for producing stretched-curd based cheeses provides to perform the step of demineralizing the skimmed milk before each step of concentrating the milk. In accordance with one aspect of the present invention, the method comprises a step of demineralizing skimmed milk, a step of concentrating the skimmed milk, a coagulation step to obtain curd, or coagulated milk, a step of stretching the curd, or coagulated milk, obtained and a step of shaping the stretched curd thus obtained. The steps are performed in this specific order.

[0020] This achieves at least the advantage of speeding up and better controlling the concentration of the skimmed milk. It should also be noted that the method according to the invention provides that the demineralization occurs before theconcentration. This allows to make the demineralization more efficient. Furthermore, this allows to reach the concentration step with skimmed milk, subsequently standardized into fatty substance, which already has a composition close to that of the final cheese to be obtained. Furthermore, the above-mentioned filtrations limit the loss of dry substances compared to draining as provided in the prior art.

[0021] In accordance with one aspect of the present invention, the concentration step provides a step of microfiltration of the demineralized skimmed milk followed by a step of ultrafiltration of the demineralized skimmed milk standardized with the correct fatty substance / dry substance ratio.

[0022] In accordance with another aspect of the present invention, at least one of either the microfiltration or the ultrafiltration is performed on a corresponding membrane, preferably both are performed on corresponding membranes.

[0023] According to another aspect of the present invention, a step of adding a fatty part, in the form of cream, to the skimmed milk is provided between the microfiltration step and the ultrafiltration step.

[0024] In accordance with another aspect of the present invention, the coagulation step is performed in a vertical coagulation apparatus. That is, the coagulation apparatus comprises a tank with a vertically oriented development axis, as well as a vertically oriented auger inside the tank.

[0025] In accordance with another aspect of the present invention, a step of de- bacterization of the skimmed milk is provided before the step of demineralizing the skimmed milk. Preferably, the de-bacterization step is performed by means of filtration, more preferably by means of microfiltration.

[0026] In accordance with another aspect of the present invention, a step of cooling the milk is provided between the concentration step and the coagulation step.

[0027] In accordance with the above purposes and to solve the technical problem described above in a new and original way, also achieving considerable advantages compared to the state of the prior art, a plant according to the present invention for producing stretched-curd based cheeses comprises, in succession, a skimmed milk demineralization apparatus, a skimmed milk concentration apparatus, a coagulation apparatus to obtain curd, or coagulated milk, a stretching apparatus for stretching the curd obtained, and a forming apparatus for shaping the stretched-curd thus obtained.

[0028] In accordance with one aspect of the present invention, at least the demineralization apparatus and the concentration apparatus are integrated into a single line.

[0029] According to one aspect of the present invention, the concentration apparatus comprises a microfiltration device and, downstream thereof, an ultrafiltration device.

[0030] DESCRIPTION OF THE DRAWINGS

[0031] These and other aspects, characteristics and advantages of the present invention will become apparent from the following description of an embodiment, given as a non-restrictive example with reference to the attached drawings wherein:

[0032] - fig. 1 is a schematic representation of a plant for producing stretched-curd based cheeses, according to the present invention;

[0033] - fig. 2 is a schematic representation of a method for producing stretched-curd based cheeses;

[0034] - fig. 3 is a graph of a capillary electrophoresis analysis to determine the whey protein content in the final product.

[0035] We must clarify that the phraseology and terminology used in the present description, as well as the figures in the attached drawings also in relation as to how described, have the sole function of better illustrating and explaining the present invention, their purpose being to provide a non-limiting example of the invention itself, since the scope of protection is defined by the claims.

[0036] To facilitate comprehension, the same reference numbers have been used, where possible, to identify identical common elements in the drawings. It is understood that elements and characteristics of one embodiment can be conveniently combined or incorporated into other embodiments without further clarifications.

[0037] DESCRIPTION OF SOME EMBODIMENTS

[0038] With reference to fig. 1, a plant 10 according to some embodiments described here is configured to produce stretched-curd based cheeses, such as mozzarella and suchlike.

[0039] In the example shown, the plant 10 comprises a milk preparation station 11, in which raw milk, that is, untreated milk, is received and possibly also stored.

[0040] Subsequently, the plant 10 comprises a pasteurization apparatus 12 forpasteurizing the milk, and a skimming apparatus 13 for performing a separation of the fatty component from the milk. An example of a skimming apparatus 13 is one of the centrifuge type. These two apparatuses are of a type commonly known in the industry.

[0041] At exit from the skimming apparatus 13 there is obtained, on the one hand, the fatty matter in the form of cream, and on the other hand, the skimmed milk. The cream is recovered and can be treated, for example pasteurized, so as to be used later in the plant 10. For this purpose, the plant 10 comprises a line 13A for the recovery and treatment of the fatty part of the milk, connected to the skimming apparatus 13. The recovery and treatment line 13 A is also connected to a subsequent apparatus of the plant 10, so as to re-inject the fatty part into it, as will be explained in more detail below.

[0042] Subsequently, the plant 10 comprises a de-bacterization apparatus 14 in which a treatment is performed aimed at lowering the quantity of bacteria in the skimmed milk. For example, the de-bacterization apparatus 14 can involve a filter, in particular a microfiltration filter, or MF filter.

[0043] In this case, from the de-bacterization apparatus 14 there are obtained the de- bacterized milk, which continues along the plant 10, and a concentrate of cells and bacteria. To facilitate the recovery and treatment of the concentrate, a corresponding line 14A for the recovery and treatment of cells and bacteria is provided, connected to the de-bacterization apparatus 14.

[0044] Downstream of the de-bacterization apparatus 14 there is provided a demineralization apparatus 15, in which the demineralization of the skimmed milk is performed. Demineralization is the lowering of the calcium concentration, usually present in milk in the form of calcium phosphate. This step is usually done by adding a demineralization substance to the milk.

[0045] In the plant 10, demineralization is performed by acidification of the skimmed milk, for example using citric acid as a demineralization substance.

[0046] For this purpose, the plant 10 advantageously comprises a line 15A for feeding the demineralization substance, connected to the demineralization apparatus 15 so that predetermined doses of the demineralization substance can be dispensed to it. The plant 10 subsequently comprises a milk concentration apparatus 16, in which the dry part, the fatty part, the protein part and the colloidal calcium areconcentrated.

[0047] In particular, the concentration apparatus 16 consists of a microfiltration device 16A and, downstream thereof, an ultrafiltration device 16B. The concentration apparatus 16 is therefore configured to perform a microfiltration and subsequently an ultrafiltration of the milk.

[0048] The microfiltration device 16A and the ultrafiltration device 16B each comprise a respective filtration membrane corresponding to the type of filtration. The membranes can be made of ceramic material or polymeric material.

[0049] A parameter to be considered in the case of microfiltration and ultrafiltration is the so-called Volumetric Concentration Factor (VCF), given by the ratio between the initial volume (foodstuff) and the final volume (retentate or concentrate).

[0050] For the microfiltration, the Applicant has identified that a VCF value useful in the embodiments described here is from 3 to 4.5, in particular from 3.1 to 4.4, more in particular from 3.15 to 4.35. Some examples are 3.1, 3.15, 3.2, 3.25, 3.3, 3.35, 3.4, 3.45, 3.5, 3.55, 3.6, 3.65, 3.7, 3.75, 3.8, 3.85, 3.9, 3.95, 4.0, 4.05, 4.1, 4.15, 4.2, 4.25, 4.3, 4.35, 4.4. Sub-ranges given by the values indicated here or similar are also contemplated.

[0051] For the ultrafiltration, the Applicant has identified that a VCF value useful in the embodiments described here is from 2 to 3.5, in particular from 2.1 to 3.4, more in particular from 2.15 to 3.35. Some examples are 2.1, 2.15, 2.2, 2.25, 2.3, 2.35, 2.4, 2.45, 2.5, 2.55, 2.6, 2.65, 2.7, 2.75, 2.8, 2.85, 2.9, 2.95, 3.0, 3.05, 3.1, 3.15, 3.2, 3.25, 3.3, 3.35, 3.4. Sub-ranges given by the values indicated here or similar are also contemplated.

[0052] Out of each of the filtration devices 16A, 16B there comes the concentrated milk, which continues along the plant 10, and a so-called “sweet serum”, which is advantageously recovered, for example by means of a recovery line 16C connected to the concentration apparatus. This “sweet serum” can be used, for example, to make other products, such as serum-based dairy products. At exit from the ultrafiltration device 16B, a concentrated milk with a chemical composition similar to that of a curd intended for stretching is instead obtained.

[0053] In the embodiment shown here, the line 13 A for the recovery and treatment of the fatty part is connected to the plant 10 between the microfiltration 16A and ultrafiltration 16B devices, so as to add the fatty part to the milk aftermicrofiltration but before ultrafiltration. Obviously, the recovery and treatment line 13A can be connected in another point of the plant 10, provided it is downstream of the skimming apparatus 13.

[0054] Cooling means 16D can also be provided between the two filtration stations to cool the milk before the ultrafiltration. It should be noted that both the microfiltration device 16A and also the ultrafiltration device 16B are equipped with heating and cooling means, not shown for simplicity, in order to be able to heat / cool the milk during the corresponding filtration, which tends to generate heat. We must clarify that the apparatuses described above are provided in line, that is, they are integrated into a single unit. It can therefore be provided that the milk is fed through the subsequent apparatuses automatically.

[0055] A cooling apparatus 17 for cooling the concentrated milk is preferably provided downstream of the concentration apparatus 16, as will be explained below. The cooling apparatus 17 can be of the heat exchanger type, in particular tubular, and can comprise one or more heat exchangers.

[0056] Immediately downstream of the cooling apparatus 17, the plant 10 comprises a milk coagulation apparatus 18, containing one or more tanks 18A and corresponding augers 18B inserted therein.

[0057] In the embodiment described here, the coagulation apparatus 18 is vertically oriented. That is, the tank 18A and the auger 18B are both oriented with a vertical development axis.

[0058] The coagulation apparatus 18 can be equipped with a feed line 18C for feeding a coagulating substance, to add a coagulating substance to the concentrated milk. The coagulating substance can be a rennet or a coagulating enzyme.

[0059] The coagulation apparatus 18 is optional, since it is possible to provide to carry out the coagulation in other coagulation systems such as, for example, basins. Furthermore, the fact of providing this vertically oriented apparatus entails the additional advantage of allowing the apparatus to be cleaned between the discharge of a quantity of milk and the loading of a subsequent quantity of milk, and therefore guaranteeing the correct microbiological conditions for coagulation are kept. Following the coagulation apparatus 18 there are provided, in a known manner, a stretching apparatus 19, a forming apparatus 20 and a packaging apparatus 21. These three apparatuses are of a type commonly known in the art. The plant 10 canalso comprise a transfer device 22 between the coagulation apparatus 18 and the stretching apparatus 19, for automatically transferring the coagulated milk to the stretching apparatus 19.

[0060] The latter is also advantageously equipped with a salt feeding device 19A, to salt the curd during stretching. This salting can be done in a commonly known manner, for example, with a brine solution.

[0061] Suitable transfer means 23, for example of the auger type, can also be provided between the stretching apparatus 19 and the forming apparatus 20 to transfer the stretched-curd.

[0062] Between the forming apparatus 20 and the packaging apparatus 21 , the plant 10 can comprise cooling means 24 for cooling the cheese prior to its packaging. The operation of the plant 10 described heretofore, which corresponds to the method 100 according to the present invention, comprises the following steps. First is a step 110 of preparing the raw milk in the preparation station 11. This step provides to receive the milk and, if necessary, store it.

[0063] A pasteurization step 120 is then performed in the pasteurization apparatus 12. The pasteurization step 120 is carried out with plants commonly known in the dairy industry.

[0064] A skimming step 130 is then performed in the skimming apparatus 13. In the embodiment described here, the skimming step is performed by milk centrifugation. During this step, on the one hand skimmed milk is obtained, which continues along the plant 10 to obtain cheeses, and on the other hand a fatty part of the raw milk is obtained, such as for example an amount of cream.

[0065] A step 131 of recovery and treatment of the fatty part thus obtained is then carried out, through the recovery and treatment line 13 A. In particular, the treatment can provide a high temperature pasteurization, so as to make the fatty part usable in latter stages of the method 100, as will be explained below.

[0066] The skimmed milk thus obtained then reaches the de-bacterization apparatus 14, where a de-bacterization step 140 occurs, in particular by microfiltration. The de- bacterization step 140 allows to obtain a milk, defined as sterile, and a concentrate of cells and bacteria, with which a recovery and treatment step 141 is performed by means of the cells and bacteria recovery and treatment line 14A. In particular, the treatment of the cell and bacteria concentrate provides a heat treatment at ultra-high temperature. This step can be considered optional in the aforementioned method, and replaced by the pasteurization step alone.

[0067] A demineralization step 150 is performed with the sterile or pasteurized milk thus obtained, aimed at eliminating part of the calcium present in the milk in the form of calcium diphosphate.

[0068] The demineralization step 150 provides, in the present example, a step 151 of feeding a demineralization substance into the milk, in particular an acid, more in particular a solution of citric and / or lactic and / or acetic acid, with or without addition of CO2. This feeding step 151 is performed by means of a feed line 15 A. After the step 151 of feeding the demineralization substance, a step of heating the milk is performed, at a temperature comprised between 30 °C and 70 °C, preferably between 40 °C and 60 °C, for example approximately 50 °C.

[0069] The demineralization step 150 is crucial in obtaining the cheese, since it affects the outcome of the future stretching of the cheese.

[0070] Following the demineralization step 150, a step 160 of concentrating the milk is provided, in correspondence with the concentration apparatus 16. In particular, in the embodiment described here, the concentration step 160 provides a microfiltration step 161 followed by an ultrafiltration step 162. These last two steps are performed in correspondence with the microfiltration device 16A and the ultrafiltration device 16B, respectively.

[0071] The concentrated milk and a so-called “sweet serum” are obtained from both the microfiltration 161 and the ultrafiltration 162 step, a step 163 of recovery of the “sweet serum” being provided. The microfiltration step 161 can be performed at a heated temperature, in particular at a temperature comprised between 30 °C and 70 °C, preferably between 40 °C and 60 °C, for example approximately 50 °C. A step 164 of cooling the concentrated milk is preferably provided between the microfiltration step 161 and the ultrafiltration step 162. For example, in this step the milk can be cooled to a temperature comprised between 0 °C and 10 °C, preferably between 2 °C and 8 °C, more preferably to 5 °C.

[0072] Furthermore, always between the microfiltration step 161 and the ultrafiltration step 162 there can be provided a step 165 of adding a fatty part to the milk, so as to adjust the desired composition. In particular, the added fatty part is advantageously the one recovered and treated following the skimming step 130described above. This addition occurs, in this case, by means of the recovery and treatment line 13 A, the outlet of which is connected between the microfiltration 16A and the ultrafiltration 16B station.

[0073] At exit from the concentration step 160, the milk obtained is transferred to the coagulation apparatus 17. Before the milk is fed to it, a cooling step 170 can be provided to bring it to a temperature more suitable for coagulation. In fact, it has been verified that temperature has an influence on coagulation, changing the consistency and appearance of the curd that is obtained after coagulation.

[0074] For example, the concentrated milk exits the concentration apparatus 16 at a temperature of between 30 °C and 70 °C, preferably between 40 °C and 60 °C, for example approximately 50 °C. It has been verified that a temperature of between 25 °C and 40 °C, preferably between 30 °C and 35 °C, for example approximately 33 °C, is favorable for optimal coagulation. The cooling step can be carried out by means of one or more heat exchangers, for example of the tubular and recirculated type.

[0075] A coagulation step 180 then takes place, in the coagulation apparatus / es 18 described above, which provides a step 181 of adding the coagulating substance, which can be for example a coagulating enzyme or a rennet.

[0076] The concentrated milk is fed at the top of the 18A tank.

[0077] At exit from the coagulation apparatus 18, by driving the vertical auger, the coagulated milk thus obtained is automatically transferred, by means of the transfer device 22, to the stretching apparatus 19, where a stretching step 190 takes place, in which a salt addition step is possibly provided, by means of the salt feeding device 19 A.

[0078] Subsequently, and in a known manner, the stretched-curd obtained is transferred, by means of the transfer means 23, to the forming station 20, where a step 200 of shaping the cheeses takes place. The cheeses are then transferred to the cooling means 24, where a further cooling step 240 takes place, and are then transferred to the packaging apparatus 21 to carry out a step 210 of packaging the cheeses, in a known manner.

[0079] This new method allows to retain a portion of whey proteins within the finished mozzarella product in a greater amount than the classic known method for obtaining stretched-curd based products, with advantages in terms of recovery andenhancement of proteins (whey proteins would otherwise be lost in the processing whey and used for further transformation in the dairy sector).

[0080] Furthermore, the Applicant has confirmed that the method described here allows to obtain a final product with comparable sensory properties with respect to the traditional known process.

[0081] EXPERIMENTAL DATA

[0082] Whey proteins

[0083] The whey proteins in the mozzarella obtained with the method described here were determined with capillary electrophoresis and compared with the traditional process (see fig. 3). For example, the peaks of alpha-lactoalbumin and betalactoglobulin are visible in the capillary electrophoresis chart.

[0084] In mozzarella obtained through the traditional method, there is a content of 1.2 to 1.6% + / - 0.02 of whey proteins of the total proteins present (weight / weight), while in the mozzarella obtained through the method described here the whey proteins are from 3 to 8% + / - 0.5 of the total proteins (weight / weight). The product obtainable through the method described here is therefore favorably enriched with whey proteins.

[0085] Sensory analysis

[0086] The product obtained with this new technology has longer and more persistent fibers, as well as having a greater juiciness, always compared with the product obtained with the classic method.

[0087] It is clear that modifications and / or additions of parts may be made to the plant 10 and to the method 100 as described heretofore, without thereby departing from the field and scope of the invention, as defined by the claims.

[0088] It is also clear that, although the present invention has been described with reference to some specific examples, a person of skill in the art will be able to achieve other equivalent forms of plant and method, having the characteristics as set forth in the claims and hence all coming within the field of protection defined thereby.

[0089] In the following claims, the sole purpose of the references in brackets is to facilitate their reading and they must not be considered as restrictive factors with regard to the field of protection defined by the claims.

Claims

CLAIMS1. Method (100) for producing stretched-curd based cheeses, characterized in that it comprises a step of demineralizing (150) skimmed milk, a step of concentrating (160) said skimmed milk, a coagulation step (180) to obtain coagulated milk, a step of stretching (190) said coagulated milk and a shaping step (200), said demineralization step (150) being performed before said concentration step (160).

2. Method (100) as in claim 1, characterized in that said concentration step (160) provides a step of microfiltration (161) and, subsequently, a step of ultrafiltration (162) of said demineralized skimmed milk.

3. Method (100) as in claim 2, characterized in that said microfiltration step (161) is performed on a microfiltration membrane, and in that said ultrafiltration step (162) is performed on an ultrafiltration membrane.

4. Method as in claim 2 or 3, characterized in that a step of adding (165) a fatty part, preferably cream, to said skimmed milk is provided between said microfiltration step (161) and said ultrafiltration step (162).

5. Method (100) as in any claim hereinbefore, characterized by providing, before said demineralization step (150), a step of de-bacterization (140) of said skimmed milk, preferably performed by means of microfiltration.

6. Method (100) as in claim 5, characterized in that said de-bacterization step (140) is performed by filtering said skimmed milk.

7. Method (100) as in any claim hereinbefore, characterized in that a step of cooling the milk is provided between said concentration step (160) and said coagulation step (180).

8. Method (100) as in any claim hereinbefore, characterized in that said coagulation step (180) is performed in a vertically oriented coagulation apparatus (18).

9. Plant ( 10) for producing stretched-curd based cheeses, characterized in that it comprises, in succession, a demineralization apparatus (15), a concentration apparatus (16), a coagulation apparatus (18), a stretching apparatus (19) and a forming apparatus (20), at least said demineralization apparatus (15) and said concentration apparatus (16) being integrated into a single line.

10. Plant (10) as in claim 9, characterized in that said concentration apparatus(16) comprises a microfiltration device (16A) and, downstream thereof, an ultrafiltration device (16B).

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