Field of application

The present invention relates to the field of fish canning industry, and in particular relates to canned tuna in brine and to a method for its production.

Background Art

A substantial part of fish canning industry is represented by tuna, sardines, salmon, anchovies and mackerel packed in glass jars or cans, under salt, under oil or in brine. The market for canned fish is constantly growing in Italy. These products, in fact, constitute an excellent source of protein at a relatively low price and thus represent, in nutritional terms, a valid and convenient alternative to fresh meat and fish.

In the particular case of canned tuna, both the Italian and international markets are performing well, both as regards the versions under oil and in brine. Canned tuna is particularly appreciated by consumers because it comes in more varieties and sizes, it is suitable for all consumption requirements (from light meals to elaborate recipes) and falls within more than one price range. From the nutritional point of view the fact is appreciated that the tuna is itself low-calorie and healthy, being rich in proteins and relatively low in fat, and yet relatively rich in polyunsaturated fatty acids (including omega-3 and omega 6, considered to have beneficial properties in the context of the prevention of cardiovascular diseases).

For example, the nutritional profile of the tuna under oil for 100 g of drained product is: water 62.3 g, protein 25.2 g, fat 10.1 g, carbohydrates 0 g, 192 kcal energy. As for tuna in brine, for 100 g of drained product, the nutritional profile is: water 73.4 g, protein 25.1 g, fat 0.3 g, 103 kcal energy (taken from the site of the National Research Institute for Food and Nutrition, F RAN).

Among the various options concerning canned tuna, tuna under oil is the market leader. For this type of product there is indeed a wide variety of options on the market, both in Italy and abroad, as regards for example the size, the quality and the origin of the tuna, the type and quality of the oil (oil, olive oil, extra-virgin olive oil, etc.), and consequently the price range in which it falls. This is followed at a great distance by canned tuna in brine, which is generally considered to be of little satisfaction in terms of taste and image and which has a still quite poor distribution penetration. Finally, there is tuna with vegetables. The most marketed species of tuna are yellowfin tuna (an oceanic species) and bluefin tuna, typical of the Mediterranean.

In recent years there has been a trend, and greater awareness, towards health among consumers, who to an increasing extent seek products which are healthy, wholesome, natural, low in fat, with reduced-salt (or sodium chloride) and reduced calories. In this context, the possibility of increasing the number of users would seem to exist and consequently also the market for canned tuna in brine.

Canned tuna in brine, in fact, besides having a healthier nutritional profile (because of its reduced fat content) compared to the version under oil, is more suitable than the latter for a variety of uses, in both hot and cold recipes, which does not however preclude the possibility of adding to the tuna an oil of the quality and in the quantity more acceptable to the consumer. The above is further supported by the fact that the widespread practice exists among consumers of canned tuna under olive oil to throw away the oil in the can before eating the tuna, as this oil is usually perceived as being of poor quality.

As mentioned above, however, canned tuna in brine is not very popular on the market, mainly because the product has a not very characteristic and pleasant flavor compared to the same product under oil, and because of its dry, fibrous or stringy texture.

In many case, the producers of canned tuna seek to improve the flavor of tuna in brine with the addition of salt in the preserving liquid.

This device does however determine a content of sodium chloride in the product which is perceived by consumers as too high, both in terms of health (it is known that an excess of sodium chloride in the diet is associated with hypertension, and consequently cardiovascular complications), and in terms of taste.

To meet the needs of the consumer, the need therefore exists to place on the market canned tuna in brine with a low salt content and improved organoleptic characteristics, which at the same time keeps the same desirable nutritional characteristics of tuna in brine, as described above, and in particular the fact of being low in calories, and a good source of protein and omega-3 and omega-6 fatty acids.

The problem underlying the present invention is therefore to make available canned tuna in brine which is nutritionally sound, relatively low in salt (sodium chloride) and with improved organoleptic characteristics, both in terms of flavor and texture, compared to canned tuna in brine currently available on the market.

Description of the Invention

A similar problem has been solved by canned tuna in brine with a reduced content of sodium chloride and improved organoleptic characteristics, essentially consisting of tuna and a preserving liquid, characterized in that said preserving liquid essentially consists of an aqueous solution of sodium chloride and yeast extract. Preferably, said yeast extract is a yeast extract powder of the Saccharomyces cerevisiae strain, preferably free of added sodium chloride.

Preferably, in the above preserving liquid the content of sodium chloride is in the range of 0.6-1.2%, more preferably 0.8-1.0%), even more preferably about 0.9%, and the content of yeast extract is in the range of 0.3-0.7%), more preferably 0.4-0.6%), even more preferably about 0.5% by dry weight out of the volume of preserving liquid. Preferably, the dry weight ratio between the quantities of yeast extract and sodium chloride present in the preserving liquid is in the range of 0.45 and 0.60.

Preferably, the above canned tuna contains a quantity of preserving liquid in the range between 25% and 35%, more preferably about 30% by weight, with respect to the total weight of the tuna and preserving liquid.

Preferably, the drained tuna of the above canned tuna contains a quantity of sodium chloride by dry weight out of 100 g of drained tuna in the range between 0.6 and 1.2 g, more preferably between 0.8 and 1.0 g, even more preferably of about 0.9 g.

The present invention also relates to a method of production of canned tuna in brine with a reduced content of sodium chloride and with improved organoleptic characteristics which comprises the steps of:

a) processing of a slice of tuna in brine consisting of water and a brine composition made up essentially of sodium citrate, sodium acetate and sodium carbonate;

b) resting of the processed slice of tuna obtained in step a) for 1.5-3 hours at a temperature between 0 and 4°C to obtain the draining of the slice of tuna;

c) portioning and packaging of the slice of tuna obtained in step b) in a can packaging with a preserving liquid consisting essentially of an aqueous solution of sodium chloride and yeast extract;

d) sealing and sterilization of the can obtained in step c) to obtain canned tuna in brine; and

e) cooling of the canned tuna in brine obtained in step d).

Preferably, in processing step a), the above-mentioned slice of tuna is raw.

Preferably, the above brine composition comprises the following ingredients (by dry weight) in the following proportions in percentage of weight out of the total dry weight of the composition: sodium citrate in a quantity in the range of 50-70%), preferably 60-

70%; sodium acetate in a quantity in the range of 10-30%), preferably 10-20%; sodium carbonate in a quantity in the range of 10-30%), preferably 10-20%).

Preferably said brine is made up of the above-mentioned brine composition in a concentration in the range between 7 and 9%, preferably about 8% by dry weight out of the volume of brine obtained.

In one embodiment, the aforementioned processing step a) comprises an injection step al) for the injection of said brine into the aforementioned slice of tuna.

Preferably, the aforesaid injection is made by syringing using a syringing unit.

Preferably, said brine is injected into said slice of tuna in a quantity in the range between 15 and 25%, more preferably about 20% by weight out of the weight of said slice of tuna before injection.

Preferably, in said slice of tuna a quantity of brine composition is injected by dry weight out of the total weight of the slice of tuna and the brine in the range between 1.0 and 2.0%, more preferably in the range between 1.1 and 1.5%, even more preferably equal to about 1.2%.

Preferably, during said injection step, said brine and said slice of tuna are at a temperature equal to or less than 5°C, preferably at a temperature between 0 and 4°C. In a second embodiment, the aforementioned processing step a) comprises a churning step a^) of said slice of tuna in the presence of the aforementioned brine at a temperature equal to or less than 5°C, preferably between 0 and 4°C under vacuum. Preferably, the churning mentioned above is carried out for a time comprised in the range between 15 and 30 minutes, more preferably between 15 and 20 minutes until absorption of said brine by the slice of tuna in a quantity in the range between 15 and 25%), more preferably about 20% by weight out of the weight of the slice of tuna before churning.

Preferably, the above churning is carried out until absorption by the slice of tuna of a quantity of brine composition by dry weight out of the total weight of the slice of tuna and the brine in the range between 1.0 and 2.0%, more preferably in the range between 1.1 and 1.5%, even more preferably equal to about 1.2%.

In a more preferred embodiment, in the aforementioned processing step a) of the slice of tuna, the injection step a^) of said brine into said slice of tuna is followed by a step of churning of said slice of tuna at a temperature equal to or less than 5°C, preferably between 0 and 4°C, under vacuum, between said injection step a^) and said churning step being optionally performed a resting step a^) of said slice of tuna for 1.5-3 hours at a temperature between 0 and 4°C to obtain the draining of the slice of tuna.

Preferably, in this embodiment, said brine is injected in said slice of tuna in a quantity in the range between 15 and 25%, more preferably about 20% by weight out of the weight of said slice of tuna before injection. Preferably, in said slice of tuna a quantity of brine composition is injected by dry weight out of the total weight of the slice of tuna and the brine in the range between 1.0 and 2.0%, more preferably in the range between 1.1 and 1.5%, even more preferably equal to about 1.2%.

Preferably, during said injection phase, said brine and said slice of tuna are at a temperature equal to or less than 5°C, preferably at a temperature between 0 and 4°C. Preferably, the above churning is carried out for a time comprised in the range between 15 and 30 minutes, more preferably between 15 and 20 minutes.

Preferably, said resting step a^) and/or said resting step b) to obtain draining of the slide of tuna last for about 2 hours, at a temperature between 0 and 4°C.

Preferably, in the above portioning and packaging step c) of the slice of tuna, in the above preserving liquid the content of sodium chloride is in the range of 0.6-1.2%), more preferably 0.8-1.0 %, even more preferably about 0.9%, and the content of yeast extract is in the range of 0.3-0.7%, more preferably 0.4-0.6%, even more preferably about 0.5 % by dry weight out of the volume of preserving liquid.

Preferably, in the above step c) said yeast extract is a yeast extract powder of the Saccharomyces cerevisiae strain, preferably free of added sodium chloride.

Preferably, in the above step c) packaging is carried out so that the dry weight ratio between the quantities of yeast extract and sodium chloride present in the preserving liquid is in the range between 0.45 and 0.60.

Preferably, in the above step c) packaging is carried out so that the aforesaid pack contains a quantity of preserving liquid in the range between 25 and 35%, more preferably about 30% by weight, with respect to the total weight of tuna and preserving liquid.

Preferably, the above sterilization step d) is carried out at 118°C for 90 minutes. These sterilization parameters are for a 190 g jar of product. Of course, the industry technician will know how to adapt these parameters to packs of different size, weight of contents, shape and type, in order to obtain a similarly suitable degree of sterilization.

Preferably, the above cooling step e) is carried out at a temperature between 0 and 4°C. The present invention also relates to brine consisting of water and a brine composition made up essentially of sodium citrate, sodium acetate and sodium carbonate.

Preferably, the above brine composition comprises the following ingredients (by dry weight) in the following proportions in percentage of weight out of the total dry weight of the composition: sodium citrate in a quantity in the range of 50-70%), preferably 60- 70%; sodium acetate in a quantity in the range of 10-30%, preferably 10-20%; sodium carbonate in a quantity in the range of 10-30%), preferably 10-20%).

Preferably said brine is made up of the above-mentioned brine composition in a concentration in the range of 7 to 9%, preferably about 8%> by dry weight out of the volume of brine obtained.

The present invention also relates to the use of the above brine of the present invention in the production of canned tuna in brine.

The present invention also relates to a preserving liquid consisting of an aqueous solution of sodium chloride and yeast extract, wherein in said preserving liquid, the content of sodium chloride is in the range of 0.6-1.2 %, more preferably 0.8-1.0%, even more preferably about 0.9%, and the content of yeast extract is in the range of 0.3-0.7%), more preferably 0.4 to 0.6%>, even more preferably about 0.5% by dry weight out of the volume of preserving liquid.

Preferably, said yeast extract is a yeast extract powder of the Saccharomyces cerevisiae strain, preferably free of added sodium chloride.

Preferably, in the above yeast extract, the content of sodium chloride is less than 5% by weight out of the weight of yeast powder.

The present invention also relates to the use of the above preserving liquid of the present invention in the production of canned tuna in brine.

Embodiments of the Invention

The present invention relates to canned tuna in brine with a reduced content of sodium chloride and improved organoleptic characteristics, essentially consisting of tuna and a preserving liquid, characterized in that the said preserving liquid is essentially made up of an aqueous solution of sodium chloride and yeast extract.

By the term "tuna" is meant here the meat of Thunnus, for example, but not limited to,

Thunnus albacore (yellow fin) or Thunnus thynnus (bluefin tuna or bluefin), Thunnus obesus (bigeye) or Katsuw onus pelamis (skipjack).

In the case of canned tuna, this is mainly in the form of a slice. The term "slice" or the phrase "slice of tuna" generally refers to a piece of tuna meat weighing more than 300 g prior to its processing. Of course the packs of canned tuna of the present invention may contain a quantity of slice of tuna of less than 300 g.

By the term "canned tuna" is meant a sealed and sterilized pack, usually tin, glass jar, or pouch, suitable for the conservation of tuna at room temperature, containing tuna and a preserving liquid. The canned tuna is consequently to be kept at room temperature. By the expression "pack for canned products" is meant a pack as described above.

By the expression "tuna in brine" or "canned tuna in brine" is meant here, in general, canned tuna in which the preserving liquid is water, aqueous solutions of salt (sodium chloride) or brine. Excluded from this definition therefore are packs containing an accompaniment of vegetables, legumes, pasta, or any other food in significant and characterizing quantities.

Here, the expression "improved organoleptic characteristics" refers to the fact that the tuna is perceived by the consumer as lighter, both in terms of salt content and flavor, and as having a more tender and juicy texture than currently available corresponding products.

By the term "drained" or by the expression "drained tuna" is meant here without the added preserving liquid. This definition is to be deemed in line with the guidelines pursuant to art. 9 Legislative Decree no. 109/92 and Reg. (EU) No.1169/2011. The standard method for determining the drained net weight of a food for Italy is described in the Official Gazette no. 266 dated 15 November 2001.

By the expression "reduced sodium chloride content" is meant here a content of sodium chloride reduced by at least 25% approx., preferably about 30%, by dry weight out of the total weight of the drained tuna, compared to a corresponding conventional product currently on the market. Conventional canned tuna contains approximately 1.5 g of sodium chloride for every 100 g of drained tuna. In other words, the canned tuna of the present invention has sodium chloride values per 100 g of drained tuna preferably within the range of 0.6-1.2 g, more preferably 0.8-1.0 g, even more preferably about 0.9 g.

The canned tuna of the present invention has in fact sodium chloride values reduced by at least 25%, preferably about 30%, by dry weight out of the drained tuna weight, compared to an equivalent conventional product.

By the expression "preserving liquid" is meant here the aqueous solution in which the canned tuna of the invention is packed and preserved. In the case of the present invention, it consists essentially of water, sodium chloride and yeast extract.

By yeast extract is meant here a non-selective cell extract, inactivated and rendered soluble (by spray tower atomization), of Saccharomyces cerevisiae.

The yeast extract of the present invention is preferably made up of a yeast extract powder of the Saccharomyces cerevisiae strain, preferably free of added sodium chloride. The yeast extract of the present invention preferably has a sodium chloride content of less than 5% by dry weight out of the dry weight of yeast powder.

In a preferred embodiment of the canned tuna of the present invention, in the above preserving liquid, the content of sodium chloride is in the range of 0.6-1.2%, more preferably 0.8-1.0%, even more preferably about 0.9% and the content of yeast extract is in the range of 0.3-0.7%), more preferably 0.4-0.6%), even more preferably about 0.5%), by dry weight out of the volume of preserving liquid.

Preferably, the yeast extract and sodium chloride are found in the preserving liquid in a dry weight ratio in the range between 0.45 and 0.60.

Preferably, the above canned tuna contains a quantity of preserving liquid in the range between 25 and 35%, more preferably about 30%> by weight with respect to the total weight of tuna and preserving liquid.

As mentioned previously, the conventional canned tuna in brine has the drawback of having a poor consumer popularity rating. Unlike tuna under oil, in fact, tuna in brine can appear somewhat flavorless and with a dry, fibrous and stringy texture.

Known art tries to solve this problem by using a high-percentage of sodium-chloride based preserving liquid. This way, the tuna preserved in such preserving liquid appears tastier.

There are however many groups of consumers who for health reasons or for personal preference or choice choose diets with a low sodium chloride content. Very salty tuna in brine is not therefore suitable for these people and is not in any case recommended in high quantities. The average content of sodium chloride in the drained tuna of conventional canned tuna in brine is about 1.5 g/100 g.

The expedient of adding sodium chloride to the preserving liquid does not, furthermore, solve the problem of the unpleasant texture of conventional tuna in brine. It has now been found that the combination of the indicated proportions of sodium chloride and yeast extract in the preserving liquid is such as to give to the canned tuna in brine of the present invention associated with it an improved taste, while at the same time retaining a reduced amount of sodium chloride, compared to corresponding conventional products.

The present invention also relates to a method for the production of canned tuna in brine with a reduced sodium chloride content and with improved organoleptic qualities, as described in the claims attached hereto.

The traditional process for the preparation of canned tuna in brine envisages first of all the cooking, usually steaming, of slices of tunas, often previously frozen, and then the packing (in cans or for example in glass jars or pouches) of the tuna slices with the addition of preserving liquid. The sealed pack is then sterilized and allowed to cool. Generally, in fact, in the fish canning industry, it is common practice to freeze the freshly caught fish. This is done to preserve the freshness of the fish, which otherwise would deteriorate very quickly during transport and/or storage.

The frozen fish then reaches the place of production of the canned tuna and is thawed. In the method of the present invention, at this point, the thawed tuna slices are processed with brine made up of water and a brine composition. As already mentioned above, in fact, the processing step a) may be preceded by a step of freezing and thawing of said slice of tuna.

The brine composition used in the present invention consists essentially of sodium citrate, sodium acetate and sodium carbonate.

At this stage of the method, the slice of tuna is preferably raw. This is because the fact that the fish is raw makes the processing step more effective. However, it is not essential that the tuna be raw.

In a preferred embodiment, the brine composition consists of the above ingredients in the following proportions (by dry weight) as a percentage by weight out of the total dry weight of the composition: sodium citrate (also known as E 331) in a quantity in the range of 50-70%, preferably 60-70%; sodium acetate (also known as E 262) in a quantity in the range of 10-30%), preferably 10-20%>; sodium carbonate (also known as E 500) in a quantity in the range of 10-30%, preferably 10-20%.

In another preferred embodiment, the above brine composition further comprises an anti-agglomerating (or antipacking) agent, preferably silicon dioxide (also known as E 551), and/or a covering agent, preferably sunflower oil.

The brine consists of the above brine composition in a concentration in the range of 7 to 9%), preferably about 8%> by dry weight out of the volume of obtained brine.

Surprisingly, it has been found, in fact, that processing with brine, such as that described in the present patent, is able to convey to the slice of tuna certain characteristics, both nutritional and organoleptic, which make the finished product tastier, with a lighter flavor than that of equivalent conventional products.

It was found, in particular, that the brine composition of the present invention is able to interact with the proteins of tuna meat so as to result in a partial fragmentation of the proteins of the tuna meat into amino acids. The muscle fibers of the tuna meat are thus more softened and the slice of tuna can then absorb and retain part of the brine in its fibers. Without because of this wishing to be bound to any theory, it is assumed that these properties of the brine are responsible for a structural, organoleptic and nutritional transformation of the slice of tuna, which is, at the end of processing, less caloric, thanks to the reduced content of integral proteins and fats and to its higher water content, and it also has an improved texture and in particular is softer and juicier, and has an improved and lighter flavor. The tuna of the present invention is therefore organoleptically more pleasing, as well as nutritionally healthy.

The protein profile of the tuna thus obtained is partially modified compared to conventional tuna inasmuch as it contains an increased percentage of total and free amino acids, or in the form of small chains of amino acids, to the detriment of integral proteins.

The processing of the slices of tunas with the above brine can be performed according to three preferred procedures.

In a first embodiment of the invention, in the processing step a), said brine is injected into the slice of tuna (injection step a ¹ )).

This operation is preferably performed, according to methods known to the industry technician, by syringing by means of a syringing unit, namely a machine with a conveyor means, e.g. a conveyor belt, and a head equipped with one or more needles.

Under a pressure of about 2 bars, a predetermined quantity of brine with a given concentration of the brine composition is injected into the slice of tuna. The speed of the conveyor means and the pressure inside the head can be easily selected by an industry technician in order to obtain the intended result.

Preferably, the brine and the slice of tuna are at a temperature equal to or less than

5°C, more preferably at a temperature between 0 and 4°C.

As mentioned above, the preferred concentration of the brine composition is in the range of 7-9%, more preferably about 8% by dry weight out of the volume of the brine.

The percentage of brine to be injected is preferably in the range of 15-25%, more preferably about 20% by weight out of the weight of the slice of tuna before processing (i.e. not syringed yet).

This corresponds to the injection of a quantity of brine composition by dry weight out of the total weight of the slice of tuna and the brine in the range between 1.0 and 2.0%, more preferably in the range between 1.1 and 1.5%, even more preferably equal to about 1.2%.

The indicated quantities of brine or brine composition are critical. A percentage less than that indicated, in fact, would not give rise, to a sufficient extent, to the desired chemical and physical changes (i.e., the changes at structural, organoleptic and nutritional level described above), and therefore to a sufficient and satisfactory nutritional and organoleptic improvement. A higher percentage would result in excessive dilution of the slice of tuna with aqueous solution and/or an over- pronounced flavor.

This consideration must be referred both to the embodiment procedure described above, and to the two embodiment procedures which will be described below.

Once the injection step a ¹ ) has been terminated, the slices are left to rest (step b)), e.g. in a positive cool cell, at a temperature between 0 and 4°C to obtain draining for 1.5-3 hours, preferably about 2 hours, e.g. stacked in trolley tanks without packaging.

The trolley tanks are essentially trolleys, usually made of steel, commonly used in the meat and fish processing industry. Typical dimensions are e.g. 750 mm x 750 mm x 700 mm.

In this resting step to obtain the draining of the slice of tuna, we have a stabilization of the diffusion and absorption phenomena within the slice structure, with percolation and draining of the excess brine. The step helps to optimize the desired effects discussed above in terms of tuna texture.

In another preferred embodiment, the processing step a) with brine of the present invention is performed by churning (step a ¹¹¹ )) under vacuum at a temperature between 0 and 4°C.

Churning consists in a processing operation by means of an apparatus called churn, and according to methods well known to the industry technician. A churn is a container usually with a substantially cylindrical or truncated-cone shape, arranged with its longitudinal axis horizontal to the ground which, by rotating along said longitudinal axis, allows the mixing of its contents. It can be equipped with a cooling jacket. It can also be fitted with a partition wall to accompany the movement of its contents during rotation. In addition, the churn can be closed hermetically, in order to keep the environment free from air, something which promotes the absorption, diffusion and retention of the brine.

Processing by churning, through the falling and beating of the slice of tuna due to the rotation of the churn, exerts a massage on the flesh of the tuna, which allows the penetration and distribution of the brine in a substantially homogeneous way inside the slice of tuna. At the same time, the tuna meat is also softened, which results in improvements from the organoleptic point of view, particularly as regards the tuna texture and softness. According to this embodiment of the method of the present invention, tuna slices are placed in the churn together with the brine described above in a predetermined amount corresponding to the amount to be absorbed by the tuna slices, in particular in a quantity in the range between 15-25%, more preferably 20% by weight out of the weight of the slice of pre-processed tuna. The churn is then operated for about 15-30 minutes, preferably 15-20 minutes, or in any case until the absorption of the desired quantity of brine, preferably 15-25%), more preferably about 20% by weight out of the weight of the slice of tuna before processing.

As above, this corresponds to the absorption of a quantity of brine composition by dry weight out of the total weight of the slice of tuna and the brine in the range between 1.0 and 2.0%, more preferably in the range between 1.1 to 1.5%, even more preferably equal to about 1.2%.

The duration of processing varies depending on the capacity of the churn and on the rotation speed (revolutions per minute) selected.

The industry technician will know how to select the rotation speed parameters, processing time, quantity of slices undergoing processing, depending on his/her own experience and the result to be obtained.

According to a third, more preferred embodiment, the processing step a) of the slice of tuna is effected by a combination of the two procedures described above and provides, in particular, the injection (step a ¹ )) of the above-indicated quantity of brine followed by a churning step. These two steps can be interrupted by a resting step (step a ¹¹ )) to obtain the draining of the slice of tuna lasting 1.5-3 hours, preferably two hours, at a temperature between 0 and 4°C.

More in particular, in this third embodiment, we have the injection (step a ¹ )) of the slice of tuna, preferably by syringing, as described above in relation to the first preferred embodiment.

A resting step a ¹¹ ) can then follow to obtain the draining of the slice of tuna, as described above. This is optional and, in the case of the procedure being performed continuously, the resting step is preferably omitted.

The slices of tunas are then subjected to a churning step, which allows massaging the tuna meat thereby favoring the distribution of the brine injected into the tuna meat. Of course, in this third preferred embodiment, the churning step does not provide for the addition of brine, when the latter has been injected, in the pre-established quantities, in the injection step described above. Except for this solution, the churning step is performed in the manner described above with reference to the second preferred embodiment.

With reference to both the second and third preferred embodiments, at the end of the churning process, the tuna slices are taken out of the churn to perform the resting step b) to obtain the draining of the slice of tuna.

At the end of processing with the brine of the invention, in fact, the tuna slices are positioned to perform the resting step b) to obtain the draining of the slice of tuna in a positive cool cell, at a temperature between 0 and 4°C for 1.5-3 hours, preferably 2 hours, e.g. placed in trolley tanks or drawers without packaging.

Once the slice of tuna has undergone the above resting step b), the slice of tuna is portioned according to the desired weight per pack, and is introduced into the pack, preferably a tin can (or can) or into a clear glass jar, or a pouch, according to methods known and conventional in the industry, in association with the preserving liquid of the invention described previously.

The preserving liquid, as already mentioned above, consists essentially of water, sodium chloride and yeast extract. The yeast extract may be a yeast extract powder of the Saccharomyces cerevisiae strain, preferably free of added sodium chloride. The yeast extract is characterized by a high sapidizing power. It is in fact characterized by a balanced content of natural nucleotides and free amino acids that enhance the perception of taste and salty notes helping to give the tuna a round and full-bodied flavor. In one of the preferred embodiments, the yeast extract consists of the commercial product Levarom 400 (Campus SpA).

The content of yeast extract in the preserving liquid is preferably in the range of 0.3- 0.7%, more preferably 0.4-0.6%, even more preferably 0.5% by dry weight out of the volume of preserving liquid.

The content of sodium chloride in the preserving liquid is preferably in the range of 0.6-1.2%), more preferably 0.8-1.0%), even more preferably about 0.9% by dry weight out of the volume of preserving liquid.

It has been found that the formulation of the preserving liquid of the present invention is able to enhance the flavor of the tuna processed according to the method of the invention.

The yeast extract does not contain, preferably, added sodium chloride. Furthermore, the preserving liquid contains a quantity of sodium chloride that is less than the quantity conventionally used, which is usually about 1.5% by dry weight out of the weight of drained tuna. Thanks to the flavor characteristics of the yeast extract, in fact, it is possible to reduce the quantity of sodium chloride by at least 25%, preferably about 30% by dry weight out of the weight of drained tuna, without negatively affecting the flavor of the final canned tuna, which will instead be improved.

The pack containing the slice of tuna and the preserving liquid is then hermetically sealed and sterilized, e.g. at 118°C for 90 minutes for a 190 g jar of product, according to the known and conventional industry methods. As already mentioned above, the industry technician will know how to adapt these parameters to packs of different size, weight of contents, shape and type, in order to obtain a similarly suitable degree of sterilization.

The sterilization is required to cook the slice of tuna and ensure it is safe from the microbiological point of view.

The industry technician is able to select the sterilization procedure suitable for ensuring the canned tuna in brine is adequately safe from a microbiological point of view, according to the resources at his/her disposal.

Sterilization is performed e.g. in an autoclave.

After sterilization, the packs of canned tuna are cooled at a temperature of 0-4°C, e.g., in a cool cell, according to the known and conventional industry methods.

The present invention also relates to the brine and the brine composition described above and to their use in the production of canned tuna in brine as described above. The present invention also relates to the preserving liquid described above and to its use for the production of canned tuna in brine as described above.

Embodiments of the present invention are described below, for illustrative and non- limiting purposes.

EXAMPLE 1

Canned tuna processed by syringing

A slice of tuna weighing 10 kg and previously frozen was thawed.

The Marinal NS (Campus S.p.A.) brine solution was used, having the following composition: sodium citrate (E 331), sodium acetate (E 262), sodium carbonate (E 500), silicon dioxide (E 551) and sunflower oil.

The brine composition was dissolved in water in a concentration of 8% by dry weight out of volume to obtain brine.

The slice of tuna was then syringed with the brine using a syringing unit of the conventional type comprising a conveyor belt with a multi-needle head and was operated so as to inject into the slice of tuna, with a pressure of around 2 bar inside the multi -needle head, a quantity of brine equal to 20% by dry weight out of the weight of the slice of tuna before syringing (i.e., equal to 2 kilos of brine). After syringing, the slice was left to rest to obtain the draining in trolley tanks without packaging in a positive cool cell at a temperature of 4°C for 2 hours.

The slice of tuna was then portioned using a portioning unit, according to conventional methods, and put into glass jars containing 190 g of tuna, with a preserving liquid in a quantity equal to around 30% by weight out of the total weight of the slice and of the preserving liquid. The preserving liquid consisted of a 0.9% sodium chloride aqueous solution and 0.5% yeast extract (Saccharomyces cerevisiae in powder or without added sodium chloride) by dry weight out of the volume of the preserving liquid.

The jars were then hermetically sealed and placed in an autoclave to undergo sterilization at 118°C for 90 minutes.

After sterilization, the jars underwent cooling in an environment at a temperature of 4°C.

EXAMPLE 2

Canned tuna processed by churning

A slice of tuna weighing 10 kg and previously frozen was thawed.

The Marinal NS (Campus S.p.A.) brine solution was used, having the following composition: sodium citrate (E 331), sodium acetate (E 262), sodium carbonate (E 500), silicon dioxide (E 551) and sunflower oil.

The brine composition was dissolved in water in a concentration of 8% by dry weight out of volume to obtain brine.

The slice of tuna was then placed in a churn together with 2 kilos of brine. The churn was operated at a rotation speed of 5 rpm, under vacuum at a temperature of 4°C until the total absorption of the brine by the slice of tuna, in this case 20 minutes.

After churning, the slice was left to rest in trolley tanks without packaging in a positive cool cell at a temperature of 4°C for 2 hours.

The slice of tuna was then portioned using a portioning unit, according to conventional methods, and put into glass jars containing 190 g of tuna, with a preserving liquid in a quantity equal to around 30% by weight out of the total weight of the slice and of the preserving liquid. The preserving liquid consisted of a 0.9% sodium chloride aqueous solution and 0.5% yeast extract (Saccharomyces cerevisiae in powder or without added sodium chloride) by dry weight out of the volume of the preserving liquid.

The jars were then hermetically sealed and placed in an autoclave to undergo sterilization at 118°C for 90 minutes.

After sterilization, the jars underwent cooling in an environment at a temperature of 4°C. EXAMPLE 3

Canned tuna processed by syringing followed by churning

A slice of tuna weighing 10 kg and previously frozen was thawed.

The Marinal NS (Campus S.p.A.) brine solution was used, having the following composition: sodium citrate (E 331), sodium acetate (E 262), sodium carbonate (E 500), silicon dioxide (E 551) and sunflower oil.

The brine composition was dissolved in water in a concentration of 8% by dry weight out of volume to obtain brine.

The slice of tuna was then syringed with the brine using a syringing unit of the conventional type comprising a conveyor belt with a multi-needle head and was operated so as to inject into the slice of tuna, with a pressure of around 2 bar inside the multi -needle head, a quantity of brine equal to 20% by weight out of the weight of the slice of tuna before syringing (i.e., equal to 2 kilos of brine).

After syringing, the slice was left to rest to obtain the draining in trolley tanks without packaging in a positive cool cell at a temperature of 4°C for 2 hours.

The slice of tuna was then placed in a churn which was operated at a rotation speed of 5 rpm, under vacuum at a temperature of 4°C for about 20 minutes.

After churning, the slice was left to rest in trolley tanks without packaging in a positive cool cell at a temperature of 4°C for 2 hours.

The slice of tuna was then portioned using a portioning unit, according to conventional methods, and put into glass jars containing 190 g of tuna, with a preserving liquid in a quantity equal to around 30% by weight out of the total weight of the slice and of the preserving liquid. The preserving liquid consisted of a 0.9% sodium chloride aqueous solution and 0.5% yeast extract (Saccharomyces cerevisiae in powder or without added sodium chloride) by dry weight out of the volume of the preserving liquid.

The jars were then hermetically sealed and placed in an autoclave to undergo sterilization at 118°C for 90 minutes.

After sterilization, the jars underwent cooling in an environment at a temperature of 4°C.

A sensorial analysis test was performed on a group of 7 tasters, aimed at comparing the popularity of the canned tuna of the present invention with the popularity of conventional canned tuna in brine. In particular, the canned tuna of the present invention was compared with a leading industry brand product and with a brand product of a leading supermarket chain, both these products being currently on the market. As can be appreciated from the results shown on Tables la - If, below, the canned tuna in brine of the present invention has improved organoleptic characteristics compared to conventional canned tuna in brine.

The tuna of the invention does in fact have an improved smell, flavor, taste and texture compared to a conventional canned tuna, and is therefore generally more popular.

It has also been seen that the greatest positive reaction came from the tasters who were the most frequent consumers of canned tuna.

Table: Smell

Taster Sample 1, Sample 2, Sample 3, canned tuna of Commercial Commercial the invention product product

SMELL 1 Intense Fishy smell

2 Intense on first Not particularly Almost impact attractive inexi stent

3 Intense and Very delicate, Stink of fish

pleasant no smell

4 Fragrant but Very salty Taste of fish and slightly acrid not much of tuna

5 Pleasant Pleasant Odorless

6 Good, very Not very Not fragrant intense fragrant

7 Strong flavor Delicate Taste of the sea

Table lb.: Taste (T: slice; L: preserving liquid; M: slice + liquid mix)

Taster Sample 1, Sample 2, Sample 3, canned tuna of Commercial Commercial the invention product product

FLAVOR 1 T: Good T: Fairly good T: Terrible

L: Good L: Fairly good L: Terrible

M: Good M: Fairly good M: Terrible

2 T: Good, slightly T: Good, rather T: No taste of bitter aftertaste salty tuna

L: Intense taste L: Slightly salty L: Watery M: I liked it and more watery M: Watery and than others bitter

M: Average not

well integrated

3 T: Fairly good T: Too strong, T: Terrible

L: Fairly good too salty L: Too salty

M: Fairly good L: Too salty M: Bad taste

M: Too much

salt, can't taste

the tuna

4 T: Very delicate, T: Salty, T: No flavor, right texture, inexistent slice inexistent slice quickly loses L: Leaves L: No flavor flavor aftertaste M: Slice too

L: Delicate and M: Too broken broken up salty, with too up

many small lost

pieces

M: Pleasant, too

thin

5 T: Good flavor, T: Good flavor, T: Flavorless, compact slice friable slice crumbly slice

L: Too salty L: No flavor L: No flavor

M: Good M: Poor M: Broken up

6 T: Delicate T: Not very T: Broken up,

L: Pleasant tasty no flavor

M: Balanced L: Too tasty L: Not tasty

M: Not M: Not rosy balanced colored, very dark

7 T: Excellent T: Tasty T: No flavor

L: Delicate L: Intense L: Too watery

M: Good M: M: Too liquid combination Table lc: Texture

Table Id.: Overall judgment

Taster Sample 1, canned Sample 2, Sample 3, tuna of the Commercial Commercial invention product product

OVERALL 1 Excellent Good Terrible

JUDGMENT 2 Good Average Poor

3 Average Poor Terrible

4 Good but rather Too broken up No flavor loses in intensity despite being

very hard

5 Good Poor Poor

6 Good Not good Inconsistent

7 Excellent Fairly good Terrible Table le.: Expectations/Flavors

Table If : Difference compared to traditional tuna in brine

In conclusion, the canned tuna of the present invention has the advantage of having a reduced amount of sodium chloride while at the same time remaining very popular with consumers in terms of organoleptic properties (in particular flavor and texture). The sodium chloride content of the drained tuna of the canned tuna of the present invention is in fact reduced by at least 25%, and up to about 30%, with respect to an equivalent conventional canned tuna.

The nutritional profile of the canned tuna of the present invention is beneficial and innovative for the industry inasmuch as the tuna has less calories and a reduced sodium chloride content. Like conventional canned tuna in brine, it also has a low lipid content and a fatty acid profile distinguished by the presence of omega-3 and omega-6 polyunsaturated fatty acids which, as is known, are associated with the prevention of cardio-vascular diseases.