WO2001032028A1

WO2001032028A1 - A cheese, a process for producing the cheese and an installation for producing the cheese

Info

Publication number: WO2001032028A1
Application number: PCT/DK2000/000619
Authority: WO
Inventors: Jørgen HENRIKSEN
Original assignee: Henriksen Joergen
Priority date: 1999-11-05
Filing date: 2000-11-06
Publication date: 2001-05-10
Also published as: AU1268901A

Abstract

A process of producing cheese in a cheese producing installation. The process comprises the steps of adding salt to a concentrate comprising water, fat and protein, and then performing a bacteria-killing treatment for killing bacteria in the salt, and then casting the concentrate into containers at a temperature between 10°C and 55° C. The invention also relates to an installation for producing cheese from a concentrate comprising protein, water and fat. The installation comprises means for providing a continuous flow of concentrate, means for adding salt to the flow of concentrate, and means for performing a bacteria-killing treatment for killing bacteria in the salt.

Description

A CHEESE, A PROCESS FOR PRODUCING THE CHEESE AND AN INSTALLATION FOR PRODUCING THE CHEESE

Technical field

The invention relates to a method and an installation for treatment of a concentrate comprising water, fat and protein in a cheese-producing process. In particular, the invention relates to a process of producing cheese, wherein salt is added to the cheese, and wherein the salt undergoes a bacteria-killing process during the cheese producing process.

Background of the invention

From the prior art it is known to treat a concentrate in a cheese producing process by leading the concentrate to a thermization unit and pumping it into a homogenizing section. Subsequently, the concentrate is heated to a cheese making temperature and led into a storage tank, wherein adding of salt for sweet types of cheeses and preripening for cheeses produced with starter culture is performed.

The thermization unit preferably comprises one or more heat exchangers, such as, e.g., plate heat exchangers, tubular heat exchangers or any kind of counterflow heat exchanger.

Typically, three storage tanks are used for salting the concentrate, a first tank being emptied to the filling plant while a second tank is being filled with concentrate from the thermization unit. Salt and other ingredients are added to the concentrate in a third tank. In prior art system wherein salt is added to a tank from the top of each tank, heavy agitation, e.g., agitation at 300 rpm, is required in order to obtain an even and satisfactorily distribution of the salt and in order to prevent sediments of salt at the bottom sections of the tanks. The temperature in the tanks is typically around 40°.

Finally, the concentrate is pumped to a filling plant, at which the concentrate is filled into containers and coagulated. In the case of an acidified cheese being produced, salt is added on top of the coagulated concentrate after a membrane has been provided on top of the concentrate. The filling plant is usually adapted to close the containers with a lid. Description of the invention

Usually, salt used in a cheese manufacturing process is free of bacteria when supplied from a salt supplier. However, it has been found that sometimes the salt contains bacteria and possibly other impurities. Until present, this problem has not been realized and dealt with, and accordingly cheese containing undesired bacteria has been produced and consumed by humans. Thus, an object of the present invention is to provide a process of producing cheese in which possible bacteria in salt added to the cheese or to the components of which the cheese is made are killed during the cheese producing process. A further object of the present invention is to provide a cheese containing salt in which the risk of the cheese containing undesired bacteria is minimized.

It has been found that, in prior art systems, grains of sand and/or other impurities originating from the salt which is added to the concentrate are difficult to remove, as the viscosity of the concentrate is relatively high at all locations downstream of location at which salt is added, as the temperature at such downstream locations is relative low. This is particularly the case when the concentrate is to be cast into containers at a relatively low temperature, such as between 10°C and 55°C. Due to the relatively high viscosity of the concentrate, a filtration of the mixture of concentrate and salt requires a fairly coarse filter in order to avoid a high pressure drop and thus a relatively high energy consumption. The coarse filter will allow the passing of fine sand particles which are undesirable in the final cheese. Those particles may also be damaging for the filter and machinery. Thus, an object of the present invention is to provide a process wherein the concentrate may be filtered at higher temperature at which the concentrate has a relatively low viscosity allowing filtration through fine-meshed filters, and wherein the concentrate may be cast into containers at a temperature between 10°C and 55°C.

Starter culture is added to the concentrate at the top of the tanks or in-line upstream of the tanks in prior art systems. Thus, the concentrate last entering the filling plant has been exposed to the activity of the starter culture for a longer period of time than the concentrate first entering the filling plant. Hence, it is an object of the present invention to provide a process in which starter culture may be added to the concentrate in such a way that an even action of starter culture in the concentrate is assured. In prior art system wherein salt is added to threes tank from the top of the tanks, heavy agitation is required in order to obtain an even and satisfactorily distribution of the salt and in order to prevent sediments of salt in the bottom section of the tanks. However, it has been found that such a heavy agitation provides the risk of drawing air into the concentrate which leads to undesired cavities in the final cheese product. Thus, an object of the present invention is to provide a process wherein heavy agitation is not required, and whereby cavities in the final cheese product are prevented.

Moreover, it has been found that in prior art system, interruptions of the processes taking place at the filling plant occur occasionally. Such interruptions may leave a major amount of concentrate in one or more of the storage tanks at a critical temperature seen from a bacteriological point of view, such as, e.g., 40°C, thereby allowing formation of bacteria. Thus, the amount of concentrate in a tank cannot be used for cheese production after an interruption in the process of, e.g., 2 hours, and the interruption will cause significant losses of concentrate. Moreover, the entire cheese production has to be interrupted, as it is undesired to keep filling concentrate into the tanks when an interruption in the filling plant has occurred. Hence, a further object of the invention is to provide a process in which a low temperature at which no or only very little bacteriological activity/growth takes place may be provided in the tank. A still further object of the invention is to provide a process in which a continuous flow of concentrate upstream of the tank can be maintained even while the processes in the filling plant are interrupted.

A further object of the invention is to provide an installation for carrying out the process fulfilling at least some of the above mentioned objects.

Thus, according to a first aspect the present invention provides a cheese being produced in a cheese producing process, the cheese comprising salt which in the cheese producing process has undergone a bacteria-killing treatment. The cheese is preferably a fresh cheese, such as a white cheese or a white cast cheese. It may, e.g., be an acidified cheese, such as a Feta cheese, an acidified or a non-acidified Domiatti cheese, Panir Sefid or Queso fresco. The cheese may preferably be produced in a cheese producing process according to a second aspect of the present invention, cf. the below description from which also a number of characteristics of the cheese according to the invention appears. According to a second aspect, the present invention provides a process of producing cheese in a cheese producing installation, the process comprising the steps of:

- adding salt to a concentrate comprising water, fat and protein, - performing a bacteria-killing treatment for killing bacteria in the salt,

- casting the concentrate into containers at a temperature between 10°C and 55°C.

The concentrate is preferably a mixture of milk powder, casein and water, or ultrafiltered retentate of raw milk. The concentrate may further comprise stabilizers and/or emulsifiers.

The step of adding salt to the concentrate may be carried out prior to or after the step of performing the bacteria-killing treatment. If salt is added prior to the bacteria-killing treatment, the concentrate containing salt is subjected to the bacteria-killing treatment. In the case that salt is added after the bacteria-killing treatment, that treatment is only carried out for the salt. In either case, the treatment preferably comprises heating the salt/the concentrate to a temperature at which no or only very few bacteria survive if that temperature is kept for a certain time interval. The salt is preferably added to the concentrate in a flow which is synchronized with the flow of the concentrate. Thus, the flow of salt merging with the flow of concentrate may be a continuous flow. Likewise, the flow of concentrate may be a continuous flow. Accordingly, the sequence of adding salt, homogenizing the concentrate and performing the bacteria-killing treatment may be performed continuously. As will be explained in detail below, a buffer tank may be provided such that even an interruption in subsequently performed process steps will not cause an interruption in the continuous process of adding salt, homogenizing and bacteria-killing.

A pre-salting may be performed prior to the step of homogenizing by adding a small amount of salt, e.g., 2-3% of the total amount of salt to be added. Subsequent to the step of casting the concentrate into containers, the remaining amount of salt may be added.

The step of performing a bacteria-killing treatment may, e.g., be performed by applying one of the following steps in a cheese-producing installation:

- subjecting the salt to a bacteria-killing treatment which is performed by appropriate means incorporated in the cheese-producing installation, the bacteria-killing treatment thereby being a process step which is not part of a sequence of process steps which the concentrate is subjected to,

- subjecting the mixture of salt and concentrate to a bacteria-killing treatment which is performed by appropriate means incorporated in the cheese-producing installation, the bacteria-killing treatment thereby being performed as one process step in a sequence of process steps which the concentrate is subjected to.

The bacteria-killing treatment may, e.g., comprise heating the mixture of salt and concentrate to a predetermined temperature and keeping the temperature for a given time interval.

The temperature of the concentrate being cast into containers may be between 12°C and 53°C, such as between 14°C and 51 °C, such as between 16°C and 49°C, such as between 18°C and 47°C, such as between 20°C and 45°C, such as between 22°C and 43°C, such as between 24°C and 41 °C, such as between 26°C and 39°C, such as between 28°C and 37°C, such as between 30°C and 35°C, such as between 32°C and 33°C.

The step of adding salt may be performed subsequent to the step of performing the bacteria-killing treatment. This is particularly useful when producing acidified cheese. Alternatively, the step of adding salt may be performed prior to the step of performing the bacteria-killing treatment which is particularly useful when producing non-acidified cheese.

As mentioned above, the bacteria in the concentrate may be killed by heating the concentrate to a thermizing temperature and maintaining the concentrate at that temperature for a first period of time. The thermizing temperature may be between 60°C and 110°C, such as between 62°C and 108°C, such as between 64°C and 106°C, such as between 66°C and 104°C, such as between 68°C and 102°C, such as between 70°C and 100°C, such as between 72°C and 98°C, such as between 74°C and 96°C, such as between 76°C and 94°C, such as between 78°C and 92°C, such as between 80°C and 90°C, such as between 82°C and 88°C, such as between 84°C and 86°C, such as approximately 85°C. At the thermizing temperature, the viscosity of the concentrate at the thermizing temperature is between 25 and 200 cp.

The first period of time may be between 5 and 25 seconds, such as between 7 and 23 seconds, such as between 9 and 21 seconds, such as between 11 and 19 seconds, such as between 13 and 17 seconds, such as between 14 and 16 seconds.

The step of casting the concentrate into containers normally comprises filling portions of liquid concentrate into containers, and subsequently coagulating the concentrate, whereby the concentrate takes the form of the container into which it is cast. In the final form, the cast cheese is preferably non-porous and substantially free of cavities.

Prior to the step of killing bacteria, the concentrate is preferably led into a homogenizer for homogenizing the concentrate. Alternatively, the step of killing bacteria may be performed prior to the step of homogenizing. Subsequently to the steps of homogenizing and killing bacteria, the concentrate is preferably cooled to an intermediate storage temperature which is lower than the thermizing temperature.

Subsequently, the concentrate may be led to a buffer tank in which the concentrate is contained or through which the concentrate is led at the intermediate storage temperature. The intermediate storage temperature is preferably between 5°C and 15°C, such as between 6°C and 14°C, such as between 7°C and 13°C, such as between 8°C and 12°C, such as between 9°C and 11°C, such as approximately 10°C. The buffer tank is primarily aimed at storing an amount of concentrate or mixture of concentrate and salt in case cheese production is interrupted for a while due to an interruption in the filling plant. Thus, all process steps occurring upstream of the buffer tank may be performed continuously without interruption even thought the filling plant is not running.

At the intermediate storage temperature, bacteriological activity is substantially eliminated or at least reduced. From the buffer tank, the concentrate is pumped or pressed to a filling plant at which the concentrate is filled into containers. When pumping the concentrate from the buffer tank to the filling plant, air is sucked into the buffer tank. In order to eliminate the risk of that air containing bacteria, the air should preferably be sterilised, and hence a sterile air filter should be provided and maintained. Instead of pumping the concentrate from the buffer tank to the filling plant, the concentrate may be pressed by pressurized air which may be pressed/pumped into the buffer tank. The pressurized air should be sterilised by, e.g., leading the air through a sterile air filter. An advantage of pressing the concentrate by means of pressurized sterile air is that regular maintenance/exchange of the filter is assured because a clogged filter will lead to an unacceptable pressure drop across the filter. However, in case the concentrate is pumped, it may happen that the sterile air filter through which air is sucked into the buffer tank is not regularly maintained, and thus the risk of dirt and impurities accumulating in the filter is relatively high.

An advantage of storing the concentrate in the buffer tank at a relatively low temperature is that the concentrate may be kept for a long period of time, such as 3 hours, with no or only very little bacteria formation happening. A homogenous mix of salt and concentrate may be obtained in case the mixture has been heated prior to reaching the buffer tank. Thus, it is prevented that sediments of salt deposit at the bottom of the buffer tank, e.g., when cheese production is interrupted for a while, and hence it is prevented that very salty portions of cheese are being produced when cheese production is resumed after an interruption.

The buffer tank may comprise an agitator for performing an agitation of the concentrate. Preferably, the agitator runs at 10 rpm.

As an alternative to cooling the concentrate to the intermediate storage temperature and leading the concentrate to the aforementioned buffer tank, the concentrate may, subsequent to the homogenizing step, be cooled to a cheese making temperature and led directly to the filling plant. In case of the production of acidified cheese, the starter and/or culture may be added to the concentrate in-line, while leading the concentrate to the filling plant. In this case, a buffer tank may be provided upstream of the filling plant. That buffer tank is primarily aimed at storing an amount of concentrate or mixture of concentrate and salt in case the cheese production is interrupted for a while due to an interruption in the filling plant or in case of starting up or closing down the cheese producing process or parts thereof. Thus, all process steps occurring upstream of the buffer tank may be performed continuously without interruption even though the filling plant is not running. This buffer tank may comprise a cooling system which is adapted to cool the concentrate to the intermediate storage temperature. At the intermediate storage temperature, bacteriological activity is substantially eliminated or at least reduced. In case the concentrate has not been contaminated during storage in the buffer tank, the concentrate may be pumped or pressed to a filling plant at which the concentrate is filled into containers. If the concentrate has been contaminated in the buffer tank, the concentrate is led back and reheated to the thermizing temperature.

This buffer tank may be mobile in that it, e.g., can be mounted on wheels, so that it can be placed at any possible position in the installation.

The cheese making temperature may be between 30°C and 50°C, such as between 31 °C and 49°C, such as between 32°C and 48°C, such as between 33°C and 47°C, such as between 34°C and 46°C , such as between 35°C and 45°C, such as between 36°C and 44°C, such as between 37°C and 43°C, such as between 38°C and 42°C, such as between 39°C and 41 °C, such as approximately 40°C. The cheese making temperature is preferably 33°C for acidified cheese and between 40°C and 45°C for non-acidified cheese, such as, e.g., 41 °C-44°C.

In case of the production of acidified cheese, the process may comprise the steps of coagulating the concentrate and adding salt to the coagulated concentrate, the bacteria- killing treatment of the salt being performed prior to adding the salt. Prior to coagulating the concentrate, the non-coagulated concentrate may be filled into a container having an opening at its top, and the concentrate may be coagulated in the container. A membrane covering the top surface of the coagulated concentrate may be applied, and salt which has undergone a bacteria-killing treatment may be added on top of the membrane. Next, the top of the container may be sealed with a lid, and the coagulated concentrate may be stored at a fermentation temperature for a second period of time, so as to obtain a given pH value of the coagulated concentrate. That pH value may be between 4.0 and 5.2, such as between 4.1 and 5.1 , such as between 4.2 and 5.0, such as between 4.3 and 4.9, such as between 4.4 and 4.8, such as between 4.5 and 4.7, such as approximately 4.6. The second period of time is usually the time elapsed between addition of starter and reaching the desired pH value. Thus, the second period of time may vary, such as between 2 hours and 24 hours or more. The fermentation temperature may be between 20°C and 30°C, such as between 21 °C and 29°C, such as between 22°C and 28°C, such as between 23°C and 27°C, such as between 24°C and 26°C, such as approximately 25°C. Having reached the proper pH value, the cheese will be cooled to a storage temperature at which it can be stored for an extended period of time, such as 6 month. The storage temperature may be between 2°C and 8°C, such as between 3°C and 7°C, such as between 4°C and 6°C, such as approximately 5°C.

In case of the production of either acidified or non-acidified cheese, the concentrate or the mixture of concentrate and salt may be led through a filter for filtering sand and other impurities from the concentrate. This is preferably done prior to the bacteria-killing treatment.

Example I

In one preferred embodiment of the process according to the invention, salt and/or additives are added into a balance tank of a thermization unit in a continuous flow synchronized with the flow of concentrate. The salt is rapidly dissolved in a regenerative section of the thermization unit which increases the temperature of the concentrate to approximately 70°C. Next, the concentrate is led through a filter for removing sand and other impurities from the concentrate and from there to a homogenizer. As the viscosity of the concentrate at the aforementioned temperature is low, the filtration may be carried out efficiently.

From the homogenizer, the flow of concentrate is led back to the thermization unit where it is heated to approximately 85°C and kept at that temperature for approximately 16 seconds. Next, the concentrate is cooled in the thermization unit to the intermediate storage temperature of 10°C.

At the intermediate storage temperature, the concentrate is led to the buffer tank in which agitation is performed by a slow moving agitator running at 10 rpm. From the buffer tank, the concentrate is pressed to the filling plant by sterile air being pressed into the buffer tank. On the way to the filling plant, the concentrate passes a heater where it is heated to a cheese making temperature of approximately 42°C.

For cheeses made with starter culture, addition of the starter culture is carried out in-line upstream of the buffer tank. The acidification process does not start until the concentrate is heated to the cheese making temperature on its way to the filling machine. This method ensures that all concentrate reaching the filling plant has been exposed to the activity of the starter culture for the same period of time. — End of example I —

Example II

In another preferred embodiment of the process according to the invention, salt and/or additives are added into a balance tank of a thermization unit in a continuous flow synchronized with the flow of concentrate. The salt is dissolved in a regenerative section of the thermization unit which increases the temperature of the concentrate to approximately 70°C. Next, the concentrate is led through a filter for removing sand and other impurities from the concentrate and from there to a homogenizer. As the viscosity of the concentrate at the aforementioned temperature is low, the filtration may be carried out efficiently.

From the homogenizer, the flow of concentrate is led back to the thermization unit where it is heated to approximately 85°C and kept at that temperature for approximately 16 seconds. Next, the concentrate is cooled in the thermization unit to the cheese-making temperature of 33°C in the case of acidified cheese and 42°C in the case of non-acidified cheese.

At the cheese-making temperature, the concentrate is led to the filling plant.

In case of an interruption in the filling plant, a moveable buffer tank may be placed upstream of the filling plant, so as to accumulate concentrate which cannot be led to the filling plant while inoperative. Agitation may be performed by a slow moving agitator running at 10 rpm in the buffer tank, and means for cooling the concentrate to the intermediate storage temperature may be provided in the buffer tank. From the buffer tank, the concentrate is pumped to the filling plant in case the concentrate has not been contaminated during the storage in the moveable buffer tank. On the way to the filling plant, the concentrate passes a heater where it is heated to a cheese making temperature of approximately 42°C for non-acidified cheese and approximately 33°C for acidified cheese. In case the concentrate has not been contaminated during the storage in the buffer tank, the concentrate may be pumped or pressed to a filling plant at which the concentrate is filled into containers. If the concentrate has been contaminated in the buffer tank, the concentrate is led back and reheated to the thermizing temperature. If the buffer tank contains diluted concentrate, that concentrate may be led back to an ultra-filtration unit for concentrating it, after which the process of homogenizing and thermizing is preferably repeated. Next, the concentrate is then led to the filling plant or to the buffer tank.

As a safety measure, the concentrate may be led from the buffer tank to the thermization unit, so as to perform thermization of the concentrate. Subsequently, the concentrate is led to the filling plant or to the buffer tank.

An additional thermization unit, e.g. for heating the concentrate from the intermediate storage temperature to the cheese making temperature, may be provided between the buffer tank and the filling plant.

For cheeses made with starter culture, such starter culture is added in-line upstream of the buffer tank. The acidification process does not start until the concentrate is heated to the cheese making temperature on its way to the filling machine. This method ensure that all concentrate reaching the filling plant has been exposed to the activity of the starter culture for the same period of time.

- End of example II —

According to a third aspect, the present invention provides an installation for producing cheese from a concentrate comprising protein, water and fat, the installation comprising:

- means for providing a continuous flow of concentrate,

- means for adding salt to the flow of concentrate,

- means for performing a bacteria-killing treatment for killing bacteria in the salt.

The installation is particularly useful for carrying out the method according to the second aspect of the invention, and consequently all aspects of the above description related to the cheese and the process according to the invention also apply to the installation according to the third aspect of the invention. It should be understood that, even if not explicitly expressed, the installation according to the invention may comprise appropriate means for carrying out the process steps and for producing the cheese, as discussed above.

The means for performing a bacteria-killing treatment for killing bacteria in the salt allows the use of non-sterile salt. As some salt suppliers provide salt containing bacteria which eventually will contaminate the final cheese product, the means for performing the bacteria-killing treatment of the salt make it possible to produce a cheese containing only extremely few undesired bacteria.

The installation may further comprise a heating device for heating the concentrate to a homogenizing temperature and a homogenizer for homogenizing the concentrate. In the homogenizer which is known perse, fat and water particles are mixed, and a homogenous mix of water and fat in the concentrate is obtained. A pipe member or tube or other means for leading the flow of concentrate from the heating device to the homogenizer is preferably provided. A further heating device for heating the concentrate to a thermizing temperature may be provided, preferably at a location downstream of the homogenizer. In the present context, the thermizing temperature corresponds to the thermizing temperature discussed above in relation with the process according to the invention. A pipe member or tube or another suitable means for leading the flow of concentrate from the homogenizer to the further heating device is preferably provided. The installation may comprise thermization means for maintaining the thermizing temperature in the flow of concentrate for a first period of time, the first period of time being discussed above in relation with the process according to the invention. A pipe or tube member or another suitable means may be provided for leading the flow of concentrate from the further heating device to the thermization means. The installation may comprise means for leading the flow of concentrate away from the thermization means for further processing of the concentrate.

A mixing tank in which the concentrate is mixed with salt may be provided at a location which is preferably upstream of the homogenizer, or at least upstream of the thermization means. Thus, the elevated temperature in the homogenizer and/or the elevated temperature in the thermization means will lead to homogeneous mixing of salt and concentrate. The installation may further comprise a cooling device for cooling the concentrate to an intermediate storage temperature which is lower than said thermizing temperature, the cooling device being preferably located at a location downstream of the thermization means. Alternatively, the installation may comprise means for cooling the concentrate to the cheese making temperature.

Downstream of the cooling device a buffer tank may be provided, the buffer tank being adapted to receive the concentrate and to contain concentrate at a temperature substantially equal to the intermediate storage temperature. At least one pipe or tube member for leading the flow of concentrate from the cooling device to the buffer tank is preferably provided. Though a plurality of buffer tanks may be provided, only a single buffer tank is needed, as described above in connection with the method according to the invention.

A filling plant comprising means for filling the concentrate into containers is preferably provided, the filling plant being located downstream of the location at which the concentrate is pasteurized. At least one pipe member for leading the concentrate to the filling plant, and means for pumping or pressing the concentrate to the filling plant may further be provided.

The buffer tank is optional; in case the concentrate has been cooled to the cheese making temperature, the concentrate need not be led via the buffer tank. However, in the latter case, a buffer tank may be provided, so as to provide a buffer for concentrate being produced in case of an interruption in downstream equipment optionally comprised in the installation. The buffer tank may comprise means for cooling the concentrate to the intermediate storage temperature defined above. Means for heating the concentrate to a cheese making temperature before the concentrate is being filled into containers in the filling plant are preferably provided in that case. Those heating means may be incorporated in or mounted to the at least one pipe member for leading the concentrate from the buffer tank to the filling plant, whereby the concentrate is being heated while being transported from the buffer tank to the filling plant.

An agitator for agitating the concentrate may be provided in the mixing tank and/or in the buffer tank. In case salt and/or other ingredients or additives have been mixed into the concentrate at the mixing tank or at the buffer tank, the agitator will contribute to maintain a homogenous mix of concentrate and salt and/or possible further ingredients or additives.

The means for pressing comprises a compressor that provides a pressure in the buffer tank by pumping sterile air into the tank.

One or more flow meters for metering the flow rate of concentrate in the installation may be provided. The flow meters may be adapted to generate an output signal to a control system for controlling the flow rate of concentrate and/or the flow rate of salt in the installation. The control system is preferably adapted to synchronize the flow of concentrate and the flow of salt merging with the flow of concentrate, so as to maintain a substantially constant ratio between the flow rate of concentrate and the flow rate of salt.

Preferably, a flow meter for metering the flow rate of concentrate is provided at an upstream location in relation to the location at which salt is mixed into the concentrate, The flow meter may be adapted to generate an output signal representing said flow rate and to pass the output signal to the control system, and the control system may be adapted to control the flow rate of salt to be mixed with the concentrate in response to the signal representing the flow rate of concentrate.

For the production of acidified cheese, salt is added to the concentrate when the concentrate has coagulated, and accordingly the filling plant of the installation preferably comprises:

- means for coagulating the concentrate in said containers,

- means for performing a heat treatment of the salt,

- means for applying a membrane to the top surface of the coagulated concentrate in each of the respective containers,

- means for filling salt into each of the respective containers on top of the membranes, - means for sealing the top of each of the respective containers with a lid.

The means for coagulating the concentrate may comprise means known perse for performing a coagulation process known per se. Thus, the means for coagulating may comprise means for maintaining the cheese making temperature of, e.g., 30-40°C for a given period of time during coagulation, such as, e.g., 20-30 minutes. Meanwhile, the containers may be transported along a conveyor.

In case salt has to be added to the coagulated concentrate, i.e. in the case of the production of acidified cheese, the bacteria-killing treatment of the salt has to be performed prior to applying the salt on top of the membrane covering the concentrate. Thus, the means for performing the heat treatment of the salt may comprise a feed screw that transports the salt while the salt is being heated to a bacteria-killing temperature. Accordingly, the feed screw may be heated to a temperature between 80°C and 120°C by means of hot steam or water.

In case of the production of non-acidified cheese, salt has usually been added to the concentrate prior to coagulation of the concentrate, and thus the installation may comprise means for coagulating the concentrate in said containers. Means for sealing the top of each of the respective containers with a lid may further be provided.

In summary, the process and the installation according to the invention has the following benefits:

1. The risk of contamination the final cheese product is eliminated or at least significantly reduced.

2. Only one buffer tank is needed instead of three tanks. Accordingly, simpler pipe runs, less chemical consumption for tank and pipe cleaning and less loss of concentrate/milk is/are achieved. This results in less pollution of waste water from the installation and the process.

3. The final cheese product contains no or very little grains of sand and other impurities.

4. Stops in the process upstream of the filling plant are prevented even if the processes occurring at the filling plant are interrupted. Brief description of the drawings

Fig. 1 shows a first embodiment of an installation for a cheese producing process according to the invention,

Fig. 2 shows a device for performing a bacteria-killing process in the salt for incorporation in an installation according to the invention,

Fig. 3 shows a second embodiment of an installation for a cheese producing process according to the invention.

Detailed description of the drawings

Fig. 1 shows a first embodiment of an installation for a cheese producing process according to the invention. The installation comprises a balance tank 1 , wherein the concentrate enters the installation subsequent to a number of process steps in a preprocessing plant (not shown). A salt dosing device 2 is positioned above the balance tank, so as to dose salt via a conveyor 2a into the concentrate in the balance tank 1 in case the step of adding salt is performed at this point in the cheese producing process. The concentrate is led from the balance tank into a plate heat exchanger 3. The concentrate is heated to a homogenizing temperature in a regenerative section 4 and led into a homogenizer 5, wherein the concentrate is homogenized. Subsequently, the concentrate is led into a further section 6 in the plate heat exchanger 3, wherein the concentrate is heated to a predetermined thermizing temperature, being higher than the homogenizing temperature. After the further section 6, the concentrate is kept at this temperature for a given period of time in a holding cell 6a. Subsequently, the concentrate is led into the opposite side of the regenerative section 4 and into a section 7, wherein the concentrate is cooled to an intermediate storage temperature being lower than the thermizing temperature.

In case the cheese requires a starter culture, the starter culture from the tanks 13 is added to the concentrate in-line upstream of the filling plant 9.

In the buffer tank 8, the concentrate with the salt is agitated by an agitator (not shown). The buffer tank is under constant pressure performed by a compressor (not shown) pumping sterile air into the buffer tank. Thereby, the concentrate is forced from the buffer tank 8 to the filling plant 9, wherein the concentrate is filled into containers.

Alternatively, the concentrate may be pumped from the buffer tank 8 to the filling plant by a pump 12.

The balance tank 1 comprises an agitator (not shown), so as to provide a satisfactorily mixing of the concentrate and salt.

The concentrate is led through the installation in pipes/tubes 10 which are provided with flow meters 11 that meter the flow of concentrate and starter/culture in the installation. The flow meters are connected to a control system for controlling the flow rate of concentrate, starter/culture and/or the flow rate of salt. The control system may, e.g., synchronize the flow of concentrate being led into the balance tank 1 and the flow of starter/culture being led from the tanks 13 and/or from the buffer tank 8 into the filling plant. Alternatively or additionally, the control system may synchronize the flow rate of concentrate and the flow rate of salt so as to obtain a substantially constant ratio between the two flow rates.

Fig. 2 shows a device for heat treating the salt which in particular may be applied in case the salt is added to the concentrate subsequently to a heat treatment of the concentrate. The device comprises a first feed screw 20 which transports the salt 21. The feed screw comprises an outer coverage 22 which is adapted to lead hot steam 23 along the housing of the feed screw, so as to heat the salt to a bacteria-killing temperature. The first feed screw transports the salt up to a second feed screw 24 which transports the salt to a receiving tank (not shown). The feed screw 24 comprises an outer coverage 25 which is adapted to lead cold water 26 along the housing of the feed screw, so as to cool the salt before adding it to the concentrate. This heat treatment of the salt is provided prior to adding salt to the concentrate, so as to prevent a contamination of the concentrate obtained by adding the salt.

Preferably, the feed screw 24 is adapted to cool the salt, but alternatively it may be adapted to heat the salt, so as to provide a further heat treatment of the salt. Fig. 3 shows a second embodiment of an installation for a cheese producing process according to the invention. The installation comprises a balance tank 1 , wherein the concentrate enters the installation subsequent to a number of process steps in a preprocessing plant (not shown). A salt dosing device 2 is positioned above the balance tank, so as to dose salt via a conveyor 2a into the concentrate in the balance tank 1 in case the step of adding salt is performed at this point in the cheese producing process. The concentrate is led from the balance tank into a plate heat exchanger 3. The concentrate is heated to a homogenizing temperature in a regenerative section 4 and led into a homogenizer 5, wherein the concentrate is homogenized. Subsequently, the concentrate is led into a further section 6 in the plate heat exchanger 3, wherein the concentrate is heated to a predetermined thermizing temperature, being higher than the homogenizing temperature. After the further section 6, the concentrate is kept at this temperature for a given period of time in a holding cell 6a. Subsequently, the concentrate is led into the opposite side of the regenerative section 4 and into a section 7, wherein the concentrate is cooled to a cheese making temperature being lower than the thermizing temperature. From the section 7, the concentrate is led to the filling plant 9, wherein the concentrate is filled into containers.

In case the cheese requires a starter culture, the starter culture is added to the concentrate in-line upstream of the filling plant through the pipe 10a.

A mobile buffer tank 8 is provided, so as to provide a buffer for concentrate being produced in case of an interruption in downstream equipment optionally comprised in the installation. The buffer tank 8 comprises means 15 for cooling the concentrate to the intermediate storage temperature with ice water. Means 12 for heating the concentrate to a cheese making temperature before the concentrate is being filled into containers in the filling plant are provided in that case. The concentrate is pumped from the buffer tank 8 to the filling plant by a pump 13.

Alternatively, the buffer tank 8 may be under constant pressure performed by a compressor (not shown) pumping sterile air into the buffer tank. Thereby, the concentrate may be forced from the buffer tank 8 to the filling plant 9, wherein the concentrate is filled into containers. A reversing valve 14 is provided, so as to control whether the flow of concentrate from the section 7 is led into the buffer tank 8 or to the filling plant 9.

The concentrate is led through the installation in pipes/tubes 10 which are provided with flow meters 11 that meter the flow of concentrate and starter/culture in the installation. The flow meters may be connected to a control system for controlling the flow rate of concentrate, starter/culture and/or the flow rate of salt. The control system may, e.g., synchronize the flow of concentrate being led into the balance tank 1 and the flow of starter/culture being led to into the concentrate through the pipe 10a and/or concentrate being led from the buffer tank 8 into the filling plant. Alternatively or additionally, the control system may synchronize the flow rate of concentrate and the flow rate of salt so as to obtain a substantially constant ratio between the two flow rates.

Claims

1. A cheese being produced in a cheese producing process, the cheese comprising salt which in the cheese producing process has undergone a bacteria-killing process.

2. A cheese according to claim 1 , the cheese being a fresh cheese, such as a white cheese, such as a white cast cheese.

3. A process of producing cheese in a cheese producing installation, the process comprising the steps of:

- adding salt to a concentrate comprising water, fat and protein,

- performing a bacteria-killing treatment for killing bacteria in the salt,

- casting the concentrate into containers at a temperature between 10° C and 55° C.

4. A process according to claim 3, wherein the cheese is a fresh cheese, such as a white cheese, such as a white cast cheese.

5. A process according to claim 4, wherein the cheese is a white cast acidified cheese.

6. A process according to claim 4, wherein the cheese is a white cast non-acidified cheese.

7. A process according to claim 3, wherein the temperature of the concentrate being cast into containers is between 12°C and 53°C, such as between 14°C and 51°C, such as between 16°C and 49°C, such as between 18°C and 47°C, such as between 20°C and 45°C, such as between 22°C and 43°C, such as between 24°C and 41 °C, such as between 26°C and 39°C, such as between 28°C and 37°C, such as between 30°C and 35°C, such as between 32°C and 33°C.

8. A process according to claim 5, wherein the step of adding salt is performed subsequent to the step of performing the bacteria-killing treatment.

9. A process according to claim 6, wherein the step of adding salt is performed prior to the step of performing the bacteria-killing treatment.

10. A process according to claim 9, further comprising:

- heating the concentrate to a homogenizing temperature, and

5 - leading the concentrate into a homogenizer for homogenizing the concentrate.

11. A process according to any of claims 3-10, comprising killing bacteria in the concentrate by heating the concentrate to a thermizing temperature and maintaining the concentrate at said temperature for a first period of time.

10

12. A process according to claim 11 , further comprising subsequent to the step of claim 11 :

- cooling the concentrate to an intermediate storage temperature which is lower than 15 said thermizing temperature,

- leading the concentrate to a buffer tank in which the concentrate is contained or through which the concentrate is led at the intermediate storage temperature.

13. A process according to claim 12, further comprising subsequent to the step of claim 20 12:

pumping or pressing the concentrate to a filling plant at which the concentrate is filled into containers,

- heating the concentrate to a cheese-making temperature prior to casting/filling the 25 concentrate into the containers.

14. A process according to claim 13, wherein the concentrate is being heated while it is being pumped or pressed to the filling plant.

30 15. A process according to claim 11 , further comprising cooling the concentrate to a cheese making temperature, subsequent to the step of claim 11.

16. A process according to claim 15, further comprising subsequent to the step of claim 15: 35 leading the concentrate to a filling plant at which the concentrate is filled into containers.

17. A process according to claim 8, wherein the bacteria-killing treatment is performed by heat treating the salt, the process comprising the steps of:

coagulating the concentrate in the filling plant, performing the heat treatment of the salt, and

- adding the salt to the coagulated concentrate.

18. A process according to claim 17, further comprising:

prior to coagulating the concentrate, filling the non-coagulated concentrate into a container having an opening at its top, - performing said step of coagulating the concentrate, applying a membrane covering the top surface of the coagulated concentrate, performing said step of adding salt by adding salt on top of the membrane, sealing the top of the container with a lid,

- storing the coagulated concentrated at a fermentation temperature for a second period of time, so as to obtain a given pH value of the coagulated concentrate.

19. A process according to claim 18, further comprising prior to the step of claim 18:

leading the concentrate into a homogenizer for homogenizing said concentrate.

20. A process according to claim 19, further comprising subsequent to the step of claim 19 and prior to the step of filling the non-coagulated concentrate into containers, the step of:

- heating the concentrate to the thermizing temperature and maintaining the concentrate at said temperature for a first period of time.

21. A process according to claim 20, further comprising subsequent to the step of claim 20: - cooling the concentrate to an intermediate storage temperature which is lower than said thermizing temperature leading the concentrate to a buffer tank in which the concentrate is contained or through which the concentrate is led at the intermediate storage temperature.

22. A process according to claim 21 , further comprising subsequent to the step of claim 21 :

pumping or pressing the concentrate to a filling plant at which the concentrate is filled into the containers, heating the concentrate to a cheese-making temperature prior to casting/filling the concentrate into the containers.

23. A process according to claim 20, further comprising cooling the concentrate to a cheese making temperature, subsequent to the step of claim 20.

24. A process according to claim 23, further comprising subsequent to the step of claim 23:

- leading the concentrate to a filling plant at which the concentrate is filled into containers.

25. A process according to claim 12 or 21 , wherein a starter culture is added to the concentrate in the buffer tank.

26. A process according to claim 16 or 24, wherein a starter culture is added to the concentrate in-line before the concentrate is being filled into containers at the filling plant.

27. A process according to any of claims 3-26, further comprising:

leading the concentrate through a filter for filtering sand and other impurities from the concentrate.

28. A process according to any of claims 12-14 or any of claims 21-27, wherein the buffer tank comprises an agitator for performing an agitation of the concentrate.

29. A process according to any of claims 12-14 or any of claims 21-28, wherein the buffer tank is under pressure, so as to force the concentrate from the buffer tank to the filling plant.

5

30. A process according to claim 29, wherein the pressure is provided by pumping sterile air into the buffer tank.

31. A process according to any of claims 11-16 or any of claims 20-30, wherein the

10 thermizing temperature is between 60°C and 110°C, such as between 62°C and 108°C, such as between 64°C and 106°C, such as between 66°C and 104°C, such as between 68°C and 102°C, such as between 70°C and 100°C, such as between 72°C and 98°C, such as between 74°C and 96°C, such as between 76°C and 94°C, such as between 78°C and 92°C, such as between 80°C and 90°C, such as between 82°C and 88°C, such

15 as between 84°C and 86°C, such as approximately 85°C.

32. A process according to claim 15 or 16 or any of claims 23-31 , wherein the cheese making temperature is between 30°C and 50°C, such as between 31 °C and 49°C, such as between 32°C and 48°C, such as between 33°C and 47°C, such as between 34°C and

20 46°C , such as between 35°C and 45°C, such as between 36°C and 44°C, such as between 37°C and 43°C, such as between 38°C and 42°C, such as between 39°C and 41 °C, such as approximately 40°C.

33. A process according to any of claims 12-16 or any of claims 21-32, wherein the 25 intermediate storage temperature is between 5°C and 15°C, such as between 6°C and

14°C, such as between 7°C and 13°C, such as between 8°C and 12°C, such as between 9°C and 11°C, such as approximately 10°C.

34. A process according to any of claims 11-16 or any of claims 20-33, wherein the first 30 period of time is between 5 and 25 seconds, such as between 7 and 23 seconds, such as between 9 and 21 seconds, such as between 11 and 19 seconds, such as between 13 and 17 seconds, such as between 14 and 16 seconds.

35. A process according to any of claims 18-34, wherein the second period of time is 35 between 2 hours and 24 hours or more.

36. A process according to any of claims 18-35, wherein the fermentation temperature is between 20°C and 30°C, such as between 22°C and 28°C, such as between 24°C and 26°C.

5

37. A process according to any of claims 18-36, wherein the pH value is between 4.0 and 5.2, such as between 4.1 and 5.1 , such as between 4.2 and 5.0, such as between 4.3 and 4.9, such as between 4.4 and 4.8, such as between 4.5 and 4.7.

10 38. A process according to claim 9, wherein the salt is added to the concentrate in a flow synchronized with the flow of the concentrate.

39. A process according to any of claims 25-38, wherein the starter culture is added to the concentrate in-line, while leading the concentrate to the buffer tank or to the filling plant.

15

40. A process according to any of claims 3-39, wherein additives that comprises ingredients, such as caraway or a stabiliser is added to the concentrate or mixture of concentrate and salt.

20 41. A process according to any of claims 3-40, wherein the viscosity of the concentrate at the thermizing temperature is between 25 cp and 200 cp.

42. An installation for producing cheese from a concentrate comprising protein, water and fat, the installation comprising: 25 means for providing a continuous flow of concentrate, means for adding salt to the flow of concentrate, means for performing a bacteria-killing treatment for killing bacteria in the salt.

30 43. An installation according to claim 42, further comprising:

- a heating device for heating the concentrate to a homogenizing temperature,

- a homogenizer for homogenizing the concentrate, at least one pipe member for leading the flow of concentrate from the heating device 35 to the homogenizer, - a further heating device for heating the concentrate to a thermizing temperature,

- at least one pipe member for leading the flow of concentrate from the homogenizer to the further heating device,

- thermization means for maintaining the thermizing temperature in the flow of concentrate for a first period of time,

- at least one pipe member for leading the flow of concentrate from the further heating device to the thermization means, means for leading the flow of concentrate away from the thermization means for further processing of the concentrate.

44. An installation according to claim 42 or 43, further comprising. a mixing tank in which the concentrate is mixed with salt.

45. An installation according to any of claims 42-44, further comprising a cooling device for cooling the concentrate to an intermediate storage temperature which is lower than said thermizing temperature or to a cheese making temperature which is lower than said thermizing temperature.

46. An installation according to any of claims 42-44, further comprising:

- a buffer tank for receiving the concentrate and being adapted to contain concentrate at a temperature substantially equal to said intermediate storage temperature,

- at least one pipe member for leading the flow of concentrate from the cooling device to the buffer tank.

47. An installation according to any of claims 42-46, further comprising a filling plant for filling the concentrate into containers.

48. An installation according to claim 45 and 47, wherein the buffer tank is moveable and adapted to be placed in and removed from a process line defined by the installation, so that:

- when the buffer tank is placed in the process line, then the concentrate is led into the buffer tank prior to being led to the filling plant, - when the buffer tank is not placed in the process line, then the concentrate is led directly from the cooling device at said cheese making temperature to the filling plant.

49. An installation according to any of claims 42-48, further comprising:

5 at least one pipe member for leading the concentrate from the buffer tank or the cooling device to the filling plant,

means for pumping or pressing the concentrate from the buffer tank or cooling device 10 to the filling plant.

50. An installation according to any of claims 42-49, further comprising means for heating the concentrate to a cheese making temperature before the concentrate is being filled into containers in the filling plant.

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51. An installation according to claim 50, wherein the heating means are incorporated in or mounted to said at least one pipe member for leading the concentrate from the buffer tank to the filling plant.

20 52. An installation according to any of claims 44-51 , wherein the mixing tank and/or buffer tank comprises an agitator for agitating the concentrate.

53. An installation according to any of claims 49-52, wherein the means for pressing comprises a compressor that provides a pressure in the buffer tank by pumping sterile air

25 into the tank.

54. An installation according to any of claims 42-53, further comprising one or more flow meters for metering the flow rate of concentrate in the installation, the flow meters being adapted to generate an output signal to a control system adapted to control the flow rate

30 of concentrate in the installation.

55. An installation according to claim 54, wherein the control system is adapted to synchronize the flow of concentrate and the flow of salt merging with the flow of concentrate, so as to maintain a substantially constant ratio between the flow rate of

35 concentrate and the flow rate of salt.

56. An installation according to claim 54 or 55, wherein a flow meter for metering the flow rate of concentrate is provided at an upstream location in relation to the location at which salt is mixed into the concentrate, said flow meter being adapted to generate an output signal representing said flow rate and to pass the output signal to the control system, the control system being adapted to control the flow rate of salt to be mixed with the concentrate in response to the signal representing the flow rate of concentrate.

57. An installation according to any of claims 47-56, wherein the filling plant further comprises:

means for coagulating the concentrate in said containers, means for performing a heat treatment of the salt, means for sealing the top of each of the respective containers with a lid.

58. An installation according to any of claims 47-57, wherein the filling plant further comprises:

means for applying a membrane to the top surface of the coagulated concentrate in each of the respective containers, means for filling salt into each of the respective containers on top of the membranes.

59. An installation according to claim 57 or 58, wherein the means for performing a heat treatment of the salt comprise a feed screw that transports the salt while the salt is being heated to a bacteria-killing temperature.

60. An installation according to claim 59, wherein the salt in the feed screw is heated to a temperature between 80°C and 120°C by means of hot steam or water.