The invention is aimed at the food industry and relates to a process for the preparation of hard cooked cheeses containing a mixture of buffalo’s, cow’s, goat’s and/or sheep’s milk. In particular, it regards making cheese from a milk obtained by mixing together buffalo’s milk and cow’s milk with the addition of goat’s and/or sheep’s milk, with or without preservatives and, after salting, aging the cheese thus obtained for at least eight months.

The subject matter of the invention also relates to the cheese obtainable through this process.

Background art

A process for producing hard cooked cheeses containing a mixture of cow’s and buffalo’s milk is known from document MI2002A001034.

By limiting oneself to only two types of milk, one would not exploit the qualities and characteristics of other types of milk available in livestock farms, such as sheep’s and goat’s milk.

Sheep’s milk is in fact a much richer milk than cow’s milk, especially in terms of fat and proteins (more than double the amount compared to cow’s and goat’s milk). In this type of milk, the ratio between proteins and the total nitrogenous matter is very high, and hence the amount of non-protein nitrogen very low, to the advantage of the biological value of the cheeses. There is a higher percentage of casein compared to cow’s milk, which means a higher yield and a greater ease of cheesemaking, and nutritional and hypoallergenic properties are imparted to the cheese. The whey proteins also have a high biological-nutritional value, with an antioxidant power (lactoferrin) and the presence of alpha-lactalbumin and beta-lactoglobulin in a higher percentage than in cow’s and goat’s milk. Goat’s milk, by contrast, has high digestibility as its main characteristic. Though the calories in goat’s milk are higher than those contained in cow’s milk, in detail its fats are better, because they are of smaller dimensions and thus more easily digestible. Furthermore, it has a lower cholesterol content, and its particular composition ensures that no increase in the latter occurs in the blood. This is possible because goat’s milk contains short-chain fatty acids, which inhibit the accumulation of cholesterol and instead favour its mobilisation from deposits. Moreover, goat’s milk is rich in isomers of conjugated linoleic acid, CLA, which, as demonstrated by some recent studies, prevent the onset of tumours, vascular diseases, atherosclerosis and even diabetes.

Unfortunately, it is nearly impossible to mix milks of different origins to make cheese, above all because both sheep’s milk and goat’s milk, as they originate from grazing animals, contain much higher bacterial loads than cow’s and buffalo’s milk, with the consequence that the development of butyric and/or propionic fermentation is practically certain.

Butyric fermentation is what generates late swelling in cheese, whereas propionic fermentation generates eyes in cheese.

A process for the production of a traditional Gouda hard cooked cheese obtained from four different types of milk - buffalo’s, cow’s, goat’s and sheep’s milk - is known from “Fourmage is a four milks cheese, buffalo, sheep, cow and goat milk” (http://cheeselandinc.com/blog/fourmage). However, traditional Gouda is produced with whole milk and has a percentage of fat greater than 3.8%.

A process for the formation of hard cooked cheeses is known from the “Dairy processing handbook 2nd rev” 1.01.2003 Tetra Pak Processing Systems AB, which does not suggest, however, what type of milk to use, nor the temperature for heating the milk at the time of adding the graft, nor even whether the milk should be skimmed or not, nor which milk should be skimmed and which should instead be used whole.

Disclosure of the invention The invention has the object of overcoming these limits.

The object of the invention is to provide a process that may enable a hard cooked cheese to be produced by processing buffalo’s milk in a mixture with cow’s milk and goat’s and/or sheep’s milk, with or without preservatives.

A further object is to obtain cheeses with a high percentage of fat and proteins, which is more digestible and contains less cholesterol.

The objects are achieved with a process for the preparation of hard cooked cheeses containing a mixture of buffalo’s, cow’s, goat’s and/or sheep’s milk according to the main independent claim 1.

The objects are likewise achieved with a cheese obtainable through the aforesaid process.

Brief description of the drawings

Additional features of the process and of the cheese thus obtained are disclosed in the dependent claims and illustrated in the appended figures, in which:

- Figure 1 summarily shows the fat, protein and casein values of the various types of milk;

- Figure 1a illustrates the experimental data of ten types of mixtures made starting from 2% partially skimmed cow’s milk, maintaining the other milks whole;

- Figure 2 illustrates the experimental data of ten types of mixtures made starting from 5% partially skimmed buffalo’s milk and 2.5% partially skimmed cow’s milk, maintaining the other milks whole;

- Figure 3 illustrates the experimental data of ten types of mixtures made starting from whole buffalo’s milk, 2.5% partially skimmed cow’s milk, 4% partially skimmed sheep’s milk and whole goat’s milk;

- Figure 4 illustrates the experimental data of ten types of mixtures made starting from 2.5% partially skimmed cow’s milk, 4% partially skimmed sheep’s milk and 3% partially skimmed goat’s milk. Detailed description of preferred embodiments of the invention

The substantial advantages of the invention are indicated below.

Buffalo’s milk has general characteristics very similar to those of cow’s milk, but also specific differences of a physicochemical nature (see Fig. 1), which can be found, for example, in the fat and protein content, respectively 8.2% and 4.5% in buffalo’s milk and about 3.9% and 3.25% in cow’s milk.

The value of fat and proteins in sheep’s milk is respectively about 7.5% and 5.6%, in goat’s milk it is about 5.3% and 3.50%.

These different values in the various types of milk inevitably lead to different characteristics in terms of the structure and consistency of the cheeses derived from them, thus imparting new flavour and characteristics to the same. Furthermore, the content of other components such as carotenoids, vitamins and lactic microflora, being different for each type of milk, determines, depending on the number of milks used (three or four) and the different percentages in the mixture, different organoleptic and colour characteristics in the products obtained.

It has surprisingly been found that, by using the thermisation technique, the difficulties described above can be overcome, while imparting characteristics of compactness to the cheese and avoiding fermentation phenomena.

Thermisation is a gentle heat treatment to which raw milk must be subjected. It is brought to a temperature of 50-55 °C for a few seconds in order to eliminate some germs that inhibit cheese production and, at the same time, leave unaffected the bacteria useful for cheesemaking, such as lactobacilli and staphylococci.

The milks to be used according to the process of the invention can be used whole or after partial skimming. For example, one can use whole buffalo’s milk and partially skimmed cow’s and goat’s and/or sheep’s milk or vice versa.

The first aspect that determines the successful production of a good cheese is that of preparing a mixture of milks (three or four) that leads to a percentage of fat that must be comprised between 2.9% and 3.8%, preferably around 3.2%.

According to the present invention, “percentage of fat” means the ratio by weight of the quantity of fatty matter relative to the total composition of the milk.

The second aspect takes into consideration the ratio between fat and casein in the milk mixture from which to produce cheese. This ratio must be comprised between 1.10 and 1.25.

From the data in Fig. 1 it may be deduced that, in order to keep the percentage of fat to within 3.8%, at least one of the milks in the mixture must be skimmed.

In some of the experiments conducted, use was made of a mixture of whole buffalo’s milk, whilst the cow’s and goat’s and/or sheep’s milk was partially skimmed, in a ratio of buffalo’s milk / other milk that ranged between 4/96 and 30/70. Advantageously, said ratio is 16/84.

The best result was obtained with a mixture with the following ratio:

10% whole buffalo’s milk 70% partially skimmed cow’s milk 10% whole goat’s milk 10% whole sheep’s milk.

But trials with other ratios also gave excellent results, for example:

25% partially skimmed buffalo’s milk;

25% partially skimmed cow’s milk;

25% partially skimmed goat’s milk;

25% partially skimmed sheep’s milk.

The most recent experiments are illustrated in figures 1a, 2, 3 and 4:

In the example in Figure 1a, with 2% partially skimmed cow’s milk and the others (buffalo’s, sheep’s, goat’s) whole, ten mixtures were created with different percentages of each component milk, but such as to maintain the final mixture with an overall fat value of less than 3.9 and a fat/casein ratio comprised between 1.10 and 1.25.

In the example in Figure 2 with 5% partially skimmed buffalo’s milk, 2.5% partially skimmed cow’s milk and the others (sheep’s, goat’s) whole, ten mixtures were created with different percentages of each component milk. In the example in Figure 3 with whole buffalo’s milk, whole goat’s milk, 2.5% partially skimmed cow’s milk and 4% partially skimmed sheep’s milk, ten mixtures were created with different percentages of each component milk.

In the example in Figure 4 with whole buffalo’s milk, 2.5% partially skimmed cow’s milk, 4% partially skimmed sheep’s and 3% partially skimmed goat’s milk, ten mixtures were created with different percentages of each component milk.

The 40 different types of mixtures illustrated gave rise to excellent products.

An experiment was conducted using at least partially skimmed buffalo’s milk and a mixture of whole or at least partially skimmed cow’s and goat’s and/or sheep’s milk mixed together with ratios ranging between 10/90 and 95/5, while maintaining the preferred and advantageous ratios and percentages of fatty matter described above.

This invention regards not only the trials conducted, but also everything concerning the production of cheeses with a mixture between buffalo’s, cow’s, goat’s and/or sheep’s milk, for an almost infinite number of combinations, which take into consideration:

- use of three or four different milks;

- use of milks of which some are whole and others partially skimmed; use of milks in percentages ranging from 0.1% to 99.9%, provided that the percentage of fat is comprised between 2.9% and 3.8% and the fat/casein ratio preferably comprised between 1.10 and 1.25.

- Depending on the mixture prepared, one will obtain cheeses that differ in terms of flavour, colour, consistency and nutritional properties. The production process comprises the following steps:

- forming a mixture comprising, in addition to buffalo’s and cow’s milk, goat’s and/or sheep’s milk, after having subjected all of the types of milk in said mixture to a thermisation process;

- if necessary or desired, adding additives and/or flavourings;

- heating the mixture and simultaneously adding a graft;

- adding rennet to obtain the coagulation of the mixture and the resulting curd;

- producing cheese by stirring, heating and cooking the curd;

- treating the cheese mass thus produced in such a way as to obtain the desired shapes; salting the cheeses and leaving them to age for at least 8 months, preferably about 14 months, so as to have a moisture content in the final product that is less than or equal to 38%, preferably less than or equal to 35%.

Skimming at least one milk of the mixture in order to reduce the fat therein to a value that is less than or equal to 3.8% makes it possible to obtain cheeses aged for a long time without the deterioration of the fat spoiling the cheese. Long aging further enables the reduced moisture content of 35-38% to be reached. Compared to fresh or semi-mature cheeses, long aging brings about the following advantages:

- more proteins;

- more vitamins;

- more minerals;

- greater digestibility (aging involves a degeneration of the fat proteins present in the milk);

- absence of lactose (or presence in trace amounts), thus suitability for those who have lactose intolerance;

- increase in the shelf life up to 365 days for the packaged product placed on the market;

- greater ease of exportation to faraway countries. The buffalo’s milk used according to the invention can be raw or pasteurised, whole or partially skimmed, as can the cow’s, goat’s and sheep’s milk.

The partial skimming can be performed according to various techniques well known to the person skilled in the art.

For example, upon arriving at the dairy the milk can be left in vats for about 5-10 hours at a temperature of 6-18 °C to allow the cream to rise to the top, after which the skimmed defatted part is drawn out and subsequently subjected to a heat treatment. For example, a heat treatment at 62-66 °C, for no less than thirty seconds and then cooling at 18-22 °C.

Other types of techniques and thermal/mechanical/physical treatments can be used within the scope of protection of the present invention in order to obtain a hard cooked cheese with a mixture of milks without preservatives and/or additives.

According to a particular non-limiting aspect of the invention, the cow’s milk is produced, stored, collected and processed in Italy.

According to another aspect of the invention, the buffalo’s milk is used within 12-48 hours after milking, or in the 3 hours after thawing, as the use of frozen buffalo’s, cow’s, goat’s and/or sheep’s milk is also envisaged.

The amounts of milk processed per batch are not critical and will be determined by the size of the cheesemaking equipment.

For example, it is possible to work with batches of 1000-5,000 litres of milk mixture or even more.

Before the step of heating the mixture and simultaneously adding a graft, it is possible to add additives, if necessary or desired, for example substances that help in the preservation of the cheese, such as lysozyme, or other suitable compounds.

The graft that is added to the milk mixture is preferably a liquid graft composed of a culture of thermophilic lactic bacteria of the type conventionally used for the preparation of hard cooked cheeses, for example a culture of bacteria selected from L.HELVETICUS, LDALBRUECKII SUBSP, BULGARICUS, L.DELBRUCEKI SUBSP.LACTIS, L.CASEI and mixtures thereof.

Simultaneously, one begins to heat the mixture to bring it to the coagulation temperature, for example to about 32-34 °C. The rennet, be it calf rennet or of vegetable, microbial and/or genetic origin, is added in a sufficient amount to obtain coagulation and the person skilled in the art is capable of determining the most suitable amount; in general it is possible to add from about 0.025 to 0.045 grams of powder rennet per litre of milk to be made into cheese, in order to obtain adequate curd. Alternatively, use can be made of liquid rennet, well known to the person skilled in the art, be it of animal origin or of vegetable, microbial or genetic origin.

The curd is subsequently cooked at an appropriate temperature. The person skilled in the art of cheesemaking will be able to choose the most suitable temperature for preparing the hard cooked cheese, which advantageously will not be lower than 55 °C and will preferably be comprised between 55 °C and 57 °C.

Then one carries out the usual operations of extracting the cheese mass from the vat, forming in a mould, overturning and affixing of marks, according to the specific processes known to the person skilled in the art. According to a preferred aspect of the present invention, after the step of treating the cheese mass so as to obtain the desired shapes, the cheeses are allowed to harden for 44-68 hours, for example in suitable rooms at a temperature of 10-15 °C.

Finally, the cheeses undergo salting, preferably by immersion in liquid brines, with a density of about 18-21 Be°, at a temperature of 16-18 °C, for about 24-28 days.

Optionally, at the end of the salting operations, the cheeses are left to dry in a warm environment for several hours before being transferred into the cheese aging facilities, normally air-conditioned to 18-20 °C, and in which a relative humidity of 70-85% is present. During the aging period, which can last for at least 8 months, advantageously about 8-14 months or more, the cheeses undergo normal overturning and the necessary conventional cleaning operations, at regular intervals, until maturation is complete.

It will be understood that the duration of the maturation period also depends on the size of the cheese produced.

The person skilled in the art will be able to identify an adequate maturation period according to the size of the cheeses prepared.

If desired, the crust of the cheeses of the invention can be “decorated” with marks or logos or coloured according to the conventional techniques. Alternatively, the crust can be treated with oils, in the ways known to the person skilled in the art.

By virtue of the presence of buffalo’s, cow’s, goat’s and/or sheep’s milk, the cheeses are particularly pleasing, rich in flavours and highly nutritious, and are suitable for a whole variety of uses, in the preparation of starters and pasta or rice dishes, as snacks, or at the end of meals or, in consideration of the high protein content due to the buffalo’s, goat’s and/or sheep’s milk, as a replacement for normal meat or fish courses, and as products also suitable for consumption by vegetarians and people who do sports.

In particular, at 12 months the cheeses with the process of the invention have a percentage of fat greater than or at least equal to 40% of the dry matter, advantageously greater than or equal to 45%, and a moisture content that is less than or equal to 38%, preferably less than or equal to 35%.

As regards organoleptic characteristics, the cheeses of the invention have a body that is pale straw yellow in colour, almost translucent, a slightly flaky structure, and a slightly sweet, robust, fresh and refined flavour. According to a preferred aspect of the invention, the cheese is processed so as to have a diameter of 35 to 45 cm, and a height comprised between 18 and 22 cm, with a weight per cheese, at the time of placement on the market, of 32-37 kg after twelve months of aging.

According to a preferred aspect of the invention, the cheeses of the invention can be shaped like cheese conventionally referred to as “Grana type”. Other shapes and sizes may naturally be given to the cheeses of the invention, according to use and the needs tied to marketing.