WO2017109745A1

WO2017109745A1 - A process for preparing mozzarella cheese from curd portions individually deep frozen by iqf technique

Info

Publication number: WO2017109745A1
Application number: PCT/IB2016/057931
Authority: WO
Inventors: Angelo Vittorio ZAMBRINI; Marco Bernardi
Original assignee: Granarolo S.P.A.
Priority date: 2015-12-23
Filing date: 2016-12-22
Publication date: 2017-06-29
Also published as: ITUB20159432A1

Abstract

Process for preparing fresh mozzarella in preserving liquid, with the same qualitative characteristics as mozzarella obtained from fresh milk. This process is characterized in that it contemplates, as single dairy component, curds coming from defrosting of individually frozen solid curd portions having parallelepiped form with longest side that has size smaller than 10 cm, preferably smaller than 5 cm, more preferably smaller than or equal to 2 cm. The defrosted curd is preferably steam-stretched in a suitable stretching machine. With this type of process, it is therefore possible to prepare the fresh mozzarella in preserving liquid in a place or nation or continent that is different from that of the curd production site, and hence it is possible to produce fresh mozzarella in preserving liquid anywhere and typically in countries where there is no abundance of milk, such as the countries of the Far East.

Description

DESCRIPTION

"A process for preparing mozzarella cheese from curd portions individually deep frozen by IQF technique"

Field of the invention:

The present invention refers to a process for producing fresh mozzarella in preserving liquid starting from a suitably-divided curd, in which the portions thus obtained are then individually frozen through the IQF (Individual Quick Freezing) process. In this manner, it is possible to produce, even in countries that are not or a are poor milk producers a fresh mozzarella in preserving liquid with characteristics identical to those of the same product prepared starting from fresh milk.

State of the art

The process for producing fresh mozzarella from fresh milk comprises the following stages.

A starter culture is added to the pasteurized milk .This culture is developed in whey or milk (whey or milk starter inoculum if the starter culture is natural, whey- ferments /milk-ferments if it is selected) or in the form of culture concentrated by direct inoculation, or by freeze drying.

A coagulant enzyme is also admixed with the starter (calf rennet or microbial rennet), generally in the amount of 25-30 ml/hl of milk, at a temperature comprised between 32°C-36°C, for the purpose of obtaining the coagulation in 20-30 minutes. The curd thus obtained is subjected to various mechanical operations in order to obtain the separation of the whey: a first cutting is made into cubes of several cubic centimeters, which are thereafter let under rest for about 10-15 minutes. By means of a second cutting, the size of the curd cubes is reduced until small cubes are obtained, having the size of a walnut. The subsequent operations comprise removing most of whey and curd maturation under whey in the case of mozzarella with greater humidity, for a time comprised between 3 and 6 hours. Alternatively, fermentation can also occur in the absence of whey, provided that suitable temperature conditions are ensured. In these conditions, the curd is turned over multiple times, on draining tables, in the course of 2-6 hours, which generally constitute the time necessary for reaching the desired pH value. Alongside conventional fermentative acidification by starters and/or by raw milk microflora, direct acidification of the milk is also possible by means of addition of organic acids such as citric acid. The latter seize the calcium and cause a precise, regular and stable decalcification; contrary to the lactic fermentation, in which the acidification tends to progress naturally, and can generate stretching defects due to excess or lack of decalcification.

With this treatment, it is sufficient to lower the pH to values of 5.5-5.8 as a function of the type of acid added and of the origin of the milk, in order to allow curd demineralization to optimal levels.

However, for lactic fermentation curds subject to stretching, the pH must be lowered to values comprised between 4.7 and 5.4 in accordance with the type of curd and milk employed, as well as with the type of cheese that one wishes to make. The stretching pH depends on the protein and calcium content in curd and on the humidity thereof. For example, the protein content is higher in mozzarella obtained from buffalo milk, since the protein fraction in the latter is higher than that contained in cow milk.

The time of acidification by curd fermentation varies between 2 and 6 hours as a function of multiple factors such as: temperature, qualitative-quantitative availability of the nutrients for the microbial starters, and last but not least the presence of possible bacteriophages.

Kneading consists of a thermomechanical operation on the ground curds at the right level of decalcification, so as to transform it into a fibrous and stringy mass.

In conventional stretching, hot water at 85-90°C is added based on the humidity content and on the fat/protein ratio of curd.

Kneading can be operated manually or with the aid of stretching machines, which can be of various type.

During this process, heat and mass transfer occur: the coagulated mass is heated, it takes up water and possibly salt, it transfers constituent water, hydrosoluble compounds and fat to the stretching water. The replacement of stretching water with steam can contribute to minimize losses of nutrients and in this manner increase the transformation yield.

After kneading, forming of the product is carried out by means of extrusion in molds generally consisting of rotating cylinders comprising recessed areas, followed by cooling in cold water, and if necessary in salt solution at 8-14°C. Finally, mozzarella is packed in preserving liquid.

The finished product thus packaged is further cooled to 4-6°C before being sold. Its lifetime during refrigeration can vary between 7 and 30 days. The product, especially if destined to markets far away from the production site, can also be frozen at temperatures less than -18°C: in this case, its duration can be extended up to 12 months. The product, once defrosted, must normally be consumed within 7 days. By frozen food, a food is meant that has undergone such a quick cooling to bring the temperature at the "core" of the product to values equal to or less than -18°C in a time less than 4 hours. Freezing facilitates the manipulation of delicate products and expands the potential area of distribution. Cold is produced mechanically or by means of cryogenic fluids such as liquid nitrogen and carbon dioxide. The direct injection, by means of specific apparatuses, of one of the aforesaid gases allows freezing or cooking the food products in a precise, modulated and localized manner. By freezing with cryogenic fluids, one obtains the micro-crystallization of the water contained in the product, and consequently the separation of various components of the cellular juices is prevented, and thus there is an improved quality of the final product.

The technique of freezing with cryogenic fluids has the following advantages with respect to that with mechanical apparatuses:

improved quality of the product due to the very limited freezing times lower losses of weight of the product, normally of the order of 0.3% high flexibility.

Nevertheless, fresh mozzarella in preserving liquid that was frozen does not have the same organoleptic characteristics after defrosting and the same durability of the fresh product.

Producing mozzarella starting from frozen curd, upon defrosting, is common practice. For example, DE10224251 describes a production process of such a type; the mozzarella prepared with such a curd type has lost a considerable amount of humidity and has poor palatability, when it is used to produce fresh mozzarella. It is in fact common practice to use frozen curd as single dairy component (only raw material) only in the preparation of dry cheeses such as 'provole' and 'scamorze', or in the preparation of cheese for pizzerias.

If the frozen curd is instead used for preparing fresh mozzarella in preserving liquid, it must be mixed in variable proportions with fresh curd produced in situ starting from fresh milk. An example of such a mozzarella type is described in US2002127301 by KRAFT, which comprises a step of freezing curd, which subsequently must be ground, defrosted and standardized in a mixer by addition of skimmed milk in powder or cream, before being stretched in steam injector.

The obtainment of fresh mozzarella in preserving liquid, starting only from frozen curd, is therefore not possible in countries that produce little or no milk.

The only process which, even if using frozen curd, does not require such a treatment type is that described in US20060172054, which is used for preparing mozzarella with low fat content; in any case, in order to obtain the necessary consistency and palatability, after defrosting farinaceous material. must be added.

The need is felt to find a process which does not have the aforesaid drawbacks, allowing therefore the production of fresh mozzarella even in countries far away from Italy.

On the other hand, the individual freezing technique is known, although it is better known as Individual Quick Freezing or IQF.

This technique allows very quickly (5-10 minutes) and effectively to freeze small- size foods, such as fruits and vegetables. IQF freezing can be carried out continuously, e.g. in a tunnel, or discontinuously, by means of freezer cabinets. The difference between the two methods is represented by the need to work with greater or lesser product quantities, and hence is ascribable to the production capacity of the plant. Both the above-described methods use, as is known, injection of cryogenic gas, preferably liquid nitrogen. The cryogenic liquid is at a temperature of -196°C, allowing to reach in the chamber of the tunnel or in the cabinets temperatures around -50-70°C permitting therefore the core of the product to quickly reach a temperature of -18°C or even lower. In this manner, the structure of the product is preserved, while reducing the weight loss a phenomenon which is usually present in juicy products subjected to a slow freezing.

SUMMARY OF THE INVENTION

The applicant has found that, for producing fresh mozzarella in preserving liquid, it is possible to process single solid frozen portions of curd obtained by individually quickly freezing (IQF) curd in the form of small parallelepipeds whose longest side has size smaller than 10 cm, more preferably smaller than 5 cm, still more preferably smaller than or equal to 2 cm., in place of processing frozen curd blocks according to the prior art.

These portions were obtained by grinding the curd, towards the end of the curdling completion step, into the aforesaid portions with parallelepiped form whose longest side has the aforesaid dimensions and by individually freezing each of said portions, hence with IQF technique.

The object of the present invention are thus frozen solid curd portions in a substantially parallelepiped form, wherein:

i) the longest side of said parallelepiped has size smaller than 10 cm,

ii) said frozen solid portions of said curd were obtained by means of individual quick freezing or IQF of curd portions with substantially parallelepiped form whose longest side has size smaller than 10 cm.

The frozen solid curd portions according to the present invention can be packaged, for example in bags, and preserved at temperatures lower than -18°C for a time equal to or greater than one year.

The applicant has also found that the frozen solid curd portions according to the present invention have further advantages if coupled with an innovative system, which allows the quick in-line defrosting thereof combined with a stretching machine operating with steam.

The frozen solid curd portions according to the present invention, being defrosted in line, allow drastically reducing defrosting times with respect to frozen curd in blocks of conventional type. At the same time, such a defrosting time reduction improves the production yield, while preventing water and hydro-soluble compound losses that are typical of the slower defrosting of large-size curd blocks.

The present invention further relates to a process for preparing fresh mozzarella in preserving liquid, which contemplates the use, as single dairy component, of curd coming from thawing the frozen solid curd portions according to the present invention

Preferably the process for preparing mozzarella according to the present invention contemplates a stage of steam kneading, upon in-line defrosting.

DETAILED DESCRIPTION OF THE INVENTION

For the purposes of the present invention, by "freezing" it is intended a treatment of industrial type that allows preserving foods and food dishes for a long period, bringing the temperature to very low values, which range from -80 °C to -18 °C, in short times. Freezing is regulated by the Italian Legislative Decree No. 110 of 27 January 1992, since it regards industrial food products. The frozen product, suitably packaged, must be integral, it must contain the indications relative to the modalities and times of preservation, the instructions for consumption and defrosting, defrosted product must only be opened by the consumer. This process is therefore different from congealing occurring at temperatures even only a few degrees below zero, which for this reason, requires much longer times. During congealing, the formation of larger ice crystals inside the product is observed. This phenomenon leads to the consequent breakage of the cellular structures and to a greater loss of water and nutritional substances.

For the purposes of the present invention, with the definition of "substantially parallelepiped form" it is intended a shape which more closely resembles that of a parallelepiped.

The division of the curds into portions, before the individual freezing thereof is carried out on the curds that have semi-solid structure, hence it is not possible to obtain such divided portions with perfect parallelepiped form; but on the contrary, it is probable that parallelepipeds will be obtained with rounded edges.

For the purposes of the present invention and, as mentioned above, IQF is the individual freezing of small-size foods, such as peas, which occurs in quicker times with respect to the conventional freezing of medium and large size foods, such as pieces of fish, slices of meat etc.

For the purposes of the present invention, by steam kneading process it is intended the process carried out in a kneading machine that employs steam at temperatures comprised between 85 and 90°C.

For the purposes of the present invention, by dairy component, it is intended that milk-derived component containing the necessary supply of fat and protein to be employed in the production of cheese, and in the specific case of fresh mozzarella in preserving liquid.

For the purposes of the present invention, with the definition of "single dairy component" it is intended that curd, coming from thawing the individually frozen solid portions, according to the present invention, and employed in the process for preparing fresh mozzarella in preserving liquid, further subject of the present invention, constitutes between 98% and 100%, preferably 100% of the total dairy component employed in the process of preparation of fresh mozzarella with preserving liquid.

The applicant has also found it possible to apply techniques of dielectric heating with radio frequencies or microwaves for the in-line defrosting of the individually frozen portions of curd, as an alternative to the in-line defrosting by means of steam injection. Through pre-conditioning, the solid portions of defined form of IQF frozen curd are defrosted before entering the kneading section. Once the defrosting of the IQF curd is completed, a single cohesive mass is obtained, which advances mechanically in the steam stretching chamber, thus allowing dosing the addition of steam and possibly of: water, and ingredients of non-cheese type, e.g. salt.

The hydration water of the IQF curd during kneading therefore mainly or totally derives from the condensation of the steam and possibly partly from a predetermined addition of water. The completely defrosted cohesive mass is then kneaded without any discard. The advantage of such a step of in-line defrosting and kneading derives from the fact that all the condensate of the steam and possibly-added water are completely absorbed by each solid portion of defined form of IQF frozen curd during defrosting, now forming a single mass that is kneaded without any discard. In this manner, one obtains mozzarella with high humidity, having desired chemical and organoleptic characteristics perfectly comparable with a mozzarella produced conventionally by means of hot water kneader.

In the employed steam kneader, curd, once defrosted in a single melt mass, is preferably kneaded by stretching. The humidity of the final mozzarella can be adjusted to values comprised between 58% and 67% by weight with respect to the total weight of said mozzarella. The kneaded curd will therefore include - due to the new process implemented by the applicant - all the fat matter and proteins initially present in the curds before kneading, without losses of mass going in the kneading liquid. A phenomenon present in the case of conventional water kneading.

The product thus obtained has the typical structure of conventional kneading: it is fibrous, elastic, with superimposed lamina.

The high number of steam injection points arranged along the entire length of the machine, together with the continuous and unidirectional flow of curd, ensures that curd is subjected to gradually-increasing temperatures, without creating points in which there are sudden increases of steam pressure that cause overheating capable of increasing the furosine values beyond the limit of 12 mg per 100 g of steam concentrations; this mild gradient ensures that the final product is less stressed and has a white color.

The kneaded curd obtained has the following characteristics: white, lucid, fibrous, elastic, it maintains humidity (about +1.5 %), it dissolves well and does not burn.

Salt can be added in the dipping arms mixing chambers; during the production process with steam-water, the entire amount of salt is absorbed by the product.

This innovative process allows:

- producing, in the country of origin, curds from fresh milk, individually freezing small portions thereof with IQF technique;

- sending the aforesaid individually frozen solid curd portions to any other country of the world, even extremely distant, ensuring high quality standards;

- kneading , in the destination country, the curd obtained via defrosting the aforesaid individually frozen solid portions, by using a steam kneader machine which allows the in-line pre-conditioning thereof, obtaining a fresh product which has the organoleptic characteristics and typical structure of the product deriving from conventional kneading.

The individual freezing or IQF of curd portions is preferably achieved by means of the use of cryogenic fluids. In this manner, with this curd type, one quickly reaches temperatures less than -18°C, thus ensuring the stop of biochemical reactions due to enzymes previously employed or deriving from the microbial activity of the starters; preserving the quality of the product (both of the curd and, subsequently, of the finished product), ensuring a lower weight loss of the product (normally of the order of 0.3%), simultaneously facilitating a high industrial flexibility.

The solid portions of IQF frozen curd, according to the present invention, are preferably small cubes, since such form allows an optimal stackability thereof during storage. The small cubes preferably have side with size comprised between 1 and 2 cm.

The curds used for preparing the frozen solid portions according to IQF, according to the present invention, can be previously flavored as described in the patent WO2014102711 in the name of the same applicant.

The mozzarella preparation process according to the present invention preferably comprises the following stages:

a) milk previously standardized in fat and protein, pasteurized, according to well-known practice to those skilled in the art, possibly: A) delactosed with a lactose content < 0.01% w/w and/or B) flavored by addition of 1 to 3 % of partially fermented milk up to pH 5.7 and 6.5 with an association of yeasts and probiotics, is subjected to acidification with a probiotic or through chemical acidification, and finally admixed with calf or microbial rennet; as an alternative to the use of delactosed milk, it is also possible, for mozzarella acidified by lactic fermentation, to add lactase together with the probiotic and leave it to act during the subsequent fermentation;

b) the curds are formed at a temperature of 35-37°C which is subsequently cut, agitated, partially or totally drained of the whey to separate the curd;

c) the acidification of the curds is completed up to pH 4.7-5.8 is reached;

d) the curds are cut into portions having parallelepiped shape whose longest side has size smaller than 10 cm, preferably smaller than 5 cm, preferably smaller than or equal to 2 cm,

e) the portions coming from the stage d) are subjected to individual quick freezing (IQF) in order to bring the core of the product to a temperature equal to or less than

-18°C, preferably through a cryogenic apparatus or by treatment with cryogenic liquids;

f) the aforesaid frozen curd portions coming from the previous stage are packed and stored at a temperature equal to or less than -18°C, and subsequently sent at the same temperature conditions to the final destination of mozzarella production;

g) the frozen solid curd portions coming from the previous stage are received and stored at a temperature equal to or less than -18°C at the site of the destination country until the moment of its further transformation;

h) in-line pre-conditioning of the frozen solid curd portions is carried out through steam or by means of dielectric endogenous heating, preferably obtained with radio frequency;

i) steam kneading is carried out for the product obtained in the preceding stage up to the temperature of 64°C+/-1°C, with possible addition of salt in the dipping arms mixing chambers, j) forming and cooling is carried out for the kneaded curd obtained in the preceding stage

k) packing in preserving liquid is carried out of the mozzarella obtained in the preceding stage.

According to a particularly preferred solution, stage h) of the process according to the present invention, i.e. in-line heating or pre-conditioning, is carried out with radio frequency technique, through an advancing belt comprising 4 live electrodes above and 5 earthed electrodes below, preferably the distance between the live electrodes and the belt is 45 mm.

The frozen product is loaded onto the belt which is heated with radio frequency, and at the end of the belt the product falls into a kneading machine.

The kneader employed in stage h) is a modular stretching machine comprising a curd feeder, a pre-stretching tunnel, with one to three chambers provided with dipping arms and a stretched curd extruder.

Any type of fresh mozzarella can be prepared by employing the frozen curd with IQF technique with the process of the invention comprising in-line heating or preconditioning and steam kneading.

For example, with the process of the invention: 'fior di latte' mozzarella or buffalo milk mozzarella, obtained from curds with lactic ferments, the so-called dietetic or light mozzarella, i.e. mozzarella with limited fat content, and finally mozzarella is obtained by direct acidification with organic acid, preferably citric acid, better defined as citric acidification can be prepared.

Reported hereinbelow are several non-limiting examples of preparation of the aforesaid mozzarella according to the present invention.

EXAMPLE 1 - LACTIC MOZZARELLA Reported in the following table 1 are the process operating conditions of 3 different experimental trials for preparing lactic mozzarella and the average theoretical yield expressed as kg of cheese deriving from the cheese-making of 100 liters of milk.

TABLE 1

According to well-known cheese practices, the milk is processed according to the above-described points a, b, c, d, in the specific case of lactic curd, probiotics and rennet are used. The curd thus obtained, after being cut in the form of small cubes with side of size comprised between 1 and 2 cm, undergoes an IQF treatment characterized by an inlet temperature equal to about 34-37°C and an outlet temperature at the core of the product (single small cube) equal to about -18°C or at lower temperatures, for the purpose of obtaining a frozen cubed curd in 5-10 minutes. The curd in the form of frozen small cubes can be immediately sent to the countries of final transformation and then used for producing the final product or be preserved at such temperatures for at least six months or even a year both at the countries of origin or in the countries of final transformation. The curd can then be subsequently processed by means of an in-line pre-conditioning step, in order to bring the curd itself to around 0°C or to higher temperatures. The pre-conditioning is achieved with a dielectric heating or steam injection heating, followed in line by the steam stretching process. By means of the pre-conditioning, the small cubes of curd are defrosted before entering the stretching section. The stretching pH reaches values comprised between 5.00 +/- 0.05 at a temperature of 64°C+/- 1°C. The above- described are followed by stages i) and j), known to those skilled in the art, as reported in the description.

The following table 2 reports the chemical characteristics of the defrosted IQF curd, of the fresh curd and of the final mozzarella on day +1 obtained with the frozen curd small-cubes according to the process of the invention.

TABLE 2

The table 3 reports the organoleptic characteristics of the finished product (appearance, structure and taste), the day after that of production ( G+1), evaluated as attributes given by a panel of 10 industry experts according a six-level scale that ranges from 0 to 5, where 0: unacceptable-very bad; 1= unacceptable-poor, 2= acceptable-mediocre; 3= acceptable-good, 4= very good, 5=optimal.

TABLE 3

Example 2- Light mozzarella with lactic fermentation

Reported in the following table 4 are the operating conditions of 3 different experimental trials for preparing mozzarella of light type with lactic fermentation and the relative average theoretical yield.

TABLE 4

According to well-known cheese-making practices, the milk is processed according to the above-described points a, b, c, d. In the specific case, since this is light mozzarella light, the lactic fermentation step for which probiotics are used is preceded by a milk skimming process with the obtainment of a fat titer of around 2- 2.2%. The curd thus obtained is cut into small cubes and subsequently undergoes an IQF treatment characterized by an inlet temperature equal to about 34-37°C and an outlet temperature equal to -18°C, or at lower temperatures in order to obtain a curd in small cubes frozen in 5-10 minutes. The curd in small-cube form, once frozen, can be immediately sent to the countries of final transformation and then used for producing the final product or be preserved at these temperatures for at least six months or even one year, either in the countries of origin or in those of destination. The curd can then be subsequently washed by means of a step of pre-conditioning for the purpose of bringing the curd itself to around 0°C or higher temperatures. The preconditioning can be obtained by a dielectric heating or steam injection heating, followed by the in-line steam stretching process. Through the pre-conditioning, the small cubes of curd are defrosted before entering into the stretching section. The stretching pH reaches values of 5.00 +/- 0.05 at a temperature of 64°C+/- 1°C. The above-described steps are followed by the process stages i) and j), known to those skilled in the art, as described in the detailed description of the invention.

The following table 5 reports the chemical characteristics of the defrosted IQF curd, compared with the fresh curd and the final mozzarella on day +1.

TABLE 5

Foodscan

Foodscan fresh defrosted Foodscan curd curd* mozzarella G+l pH 5.1 5.14 5.34

Humidity 52.61 52.72 69

Fat 12.3 12 9 Proteins 25 25 18

Fat, dry weight 28 28 27.5

Dry residue 47.39 47.28 31

* analysis made if the curd is treated with radio frequency heating

Table 6 reports the organoleptic characteristics of the finished product (appearance, structure and taste), the day after that of production ( G+1), evaluated as attributes given by a panel of industry experts according a six-level scale that ranges from 0 to 5, where 0: unacceptable-very bad; 1= unacceptable-poor, 2= acceptable-mediocre; 3= acceptable-good, 4= very good, 5=optimal. The evaluation is reported in example 2.

Table 6- Properties of mozzarella 2

Example - 3: Buffalo milk mozzarella

Reported in the following table 7 are the operating conditions of 3 separate tests for preparing buffalo mozzarella with lactic fermentation and the relative average theoretical yield.

TABLE 7

Test No. a) b) c)

CURD TYPE Buffalo Buffalo Buffalo

IQF Yes Yes Yes

Pre -conditioning Radio frequency Steam Steam final stretched curd T°C 65°C 65°C 65°C

average stretching time 20 min

Average theoretical yield 26%

According to well-known cheese-making practices, the milk is processed according to the above-described points a, b, c, d. In the specific case, the starting milk is from buffalo, the lactic fermentation step encompasses the inoculation of probiotics and subsequently of rennet at the temperature comprised between 36-38°C. About 80 minutes after the addition of rennet, the curdling is broken and the obtained curd is left to mature under whey up to pH= 5.1-5.15 for 5 hours. Subsequently, curd is removed from whey and completely discharged up to pH=4.95. The curd thus obtained is cut into small cubes and subsequently undergoes a IQF treatment characterized by an inlet temperature of about 34-37°C and an outlet temperature equal to about -18°C or at lower temperatures, for obtaining a cubed curd that is frozen in 5-10 minutes. The curd in the form of small cubes, frozen, can be immediately sent to the countries of final transformation and then used for producing the final product or be preserved at such temperatures for at least six months or even one year in the countries of origin or in the destination countries. The curd can then be subsequently washed by means of a pre-conditioning step for the purpose of bringing the curd itself to around 0°C. Pre-conditioning comprises a dielectric heating or steam injection heating, followed by the steam stretching process. Bu preconditioning the small cubes of curd are defrosted before entering the stretching section. The stretching pH reaches values of 4.95 +/- 0.05 at a temperature of 64°C+/- 1°C. The above-described steps are followed by process stages i) and j), known to those skilled in the art, as described in the detailed description of the invention. The table 8 reports the chemical characteristics of the defrosted IQF curd, of mozzarella obtained therefrom and compared with fresh curd.

TABLE 8

Table 9 reports the organoleptic characteristics of the finished product (appearance, structure and taste), the day after that of production ( G+1), evaluated for attributes by a panel of industry experts according a six-level scale that ranges from 0 to 5, where 0: unacceptable-very bad; 1= unacceptable-poor, 2= acceptable-mediocre; 3= acceptable-good, 4= very good, 5=optimal.

Table 9- Properties of mozzarella 3

Time of Appearance Structure Taste Overall tasting evaluation

G+1 4 4 4 4 Example - 4 Mozzarella: citric

The following table 10 reports the operating conditions of 3 separate tests for preparing mozzarella with citric acid fermentation or citric fermentation and the relative average theoretical yield with the process of the invention.

Table 10

According to well-known cheese-making practices, the milk is processed according to the above-described points a, b, c, d. In the specific case, being citric mozzarella, the step of acidification is obtained by means of citric acid. The curd thus obtained, after total discharge of the whey, is transformed into small cubes and then undergoes an IQF treatment characterized by an inlet temperature equal to about 34-37°C and an outlet temperature equal to -18°C° or at lower temperatures, for obtaining a frozen cubed curd in 5-10 minutes. The frozen curd in the form of small cubes, can be immediately sent to the countries of final transformation and then used for producing the final product or be preserved at such temperatures for at least six months or even one year in the countries of origin or in the destination countries. The curd can then be subsequently washed by means of a pre-conditioning step for the purpose of bringing the curd itself to around 0°C or higher temperatures. The pre-conditioning can be obtained by a dielectric heating or steam injection heating, followed by the inline steam stretching process. Through the dialectic pre-conditioning the small cubes of curd are defrosted before entering into the stretching section; while by means of steam injection, the small cubes of curd enter into the stretching section still at temperatures less than 0°C and are subsequently defrosted here. The stretching pH reaches values of 5.95 +/- 0.05 at a temperature of 64°C+/- 1°C. The above- described steps are followed by process stages i) and j), known to those skilled in the art, as described in the detailed description of the invention.

The table 11 reports the chemical characteristics of the defrosted IQF curd of the mozzarella obtained therefrom and compared with the fresh curd and of mozzarella obtained with the process of the invention on day +1

TABLE 11

Foodscan Foodscan

Foodscan defrosted mozzarella fresh curd curd* G+l

pH 5.75 5.75 5.9

Humidity 46.88 46.88 60

Fat 25.12 25.12 18.5

Proteins 24.28 24.28 18

Fat, dry weight 47.29 47.29 46

Dry residue 0.1 0.1 0.32 analysis made if the curd is treated with dielectric heating

The table 12 reports the organoleptic characteristics of the finished product (appearance, structure and taste), the day after that of production ( G+1), evaluated for attributes by a panel of industry experts according a six-level scale that ranges from 0 to 5, where 0: unacceptable-terrible; 1= unacceptable-poor, 2= acceptable- mediocre; 3= acceptable-good, 4= very good, 5=optimal. The evaluation is reported in example 4.

Table 12 - Properties of mozzarella 4

Time of tasting Appearance Structure Taste Overall

evaluation

G+1 5 4 4 4

Claims

1. Solid frozen portions of curd in a substantially parallelepiped form of curd wherein:

i) the longest side of said parallelepiped has size lower than 10 cm;

ii) said frozen solid portions of curd are obtained by individually quick freezing (IQF) each curd portion having substantially parallelepiped form whose longest size has dimension lower than 10 cm.

2. Solid frozen portions of curd according to claim 1, wherein longest size of said parallelepiped has dimension lower than 5 cm.

3. Solid frozen portions of curd according to claims 1 or 2 wherein the longest size of said parallelepiped has dimension lower or equal to 2 cm.

4. Solid frozen portions of curd according to any one of claims 1 -3, wherein said parallelepiped is a cube.

5. Solid frozen portions of curd according to claim 4, wherein said cube has size comprised between 1 and 2 cm.

6. A process for preparing fresh mozzarella in a preserving liquid comprising the use as the only dairy-milk component of a curd coming from thawing said curd solid frozen portions according to anyone of claims 1-5.

7. The process according to claim 6, wherein said thawing is combined with a kneading process of the thawed curd by a steam kneading.

8. The process according to claim 7, wherein said thawing is a pre-conditioning step carried out in line by means of dielectric heating and/or steam injection heating at temperatures comprised between 85 and 90°C.

9. The process according to claim 8, wherein said dielectric heating is obtained with radio frequency or with microwaves.

10 The process according to anyone of claims 6-9, comprising the following stages: a) milk previously standardised in fat and protein, pasteurised, according to a practice well-known to those skilled in the art, possibly: A) delactosed with a lactose content < 0.01% p/p and/or B) flavoured by addition of 1 to 3 % of partially fermented milk up to pH 5.7 and 6.5 with an association of yeasts and lactic bacteria , is subjected to fermentative acidification through lactic bacteria or through chemical acidification, and finally added to with calf or microbial rennet; or as an alternative to delactosation, milk added with lactase is added together with the lactic bacteria and it is left to act during the subsequent fermentation,

b) the curd forms at a temperature of 35-37°C, which is subsequently cut, agitated, partially or totally drained of the whey to separate curd from whey, c) the acidification of the curd is completed until pH 4.7-5.8 is reached;

d) the curd is cut into portions having the form of a parallelepiped, whose longest side has dimensions lower than 10 cm, preferably lower than 5 cm more preferably equal or lower than 2 cm;

e) the curd portions coming from the previous stage d) are subjected to individual quick freezing (IQF) process to bring the core of the product to a temperature equal to or less than -18°C, preferably through a cryogenic apparatus or by treatment with cryogenic liquids;

f) the frozen solid curd portions coming from stage e) are packed and stored in defined portions preferably in the form of small cubes at a temperature equal to or less than -18°C and sent, at the same temperature conditions, to the final site of mozzarella production; g) the frozen solid portions coming from the previous stage are received at the location of the destination country and stored at a temperature equal to or less than - 18°C until the moment of their further transformation;

i) steam kneading is carried out for the product obtained in the preceding stage up to the temperature of 64°C+/-1°C, with possible addition of salt in the dipping arms mixing chambers,

j) forming and cooling is carried out for the stretched curd obtained in the preceding stage

11. The process according to claim 9, wherein step f) is carried out with radio frequency technique, through an advancing belt with 4 live electrodes above and 5 earthed electrodes below, preferably the distance between the live electrodes and the belt is 45 mm.

12. The process according to claim 10 or 11, wherein steam kneader used in step g) is a modular stretching machine comprising a curd loader, a pre-stretching tunnel, with one to three chambers with dipping arms and a stretched curd extruder.