FIELD OF THE INVENTON

The present invention relates to a system and a method for the production of acidified white cheese filled in containers which can be closed prior to the coagulation of the UF (ultra filtered) retentate or a mix produced from milk protein, vegetable- or animal fat and water. Three ingredients are added to the retentate/mix produced from milk protein, vegetable- and/or animal fat and water before filling NaCI, GDL (glucono delta-lactone) and rennet.

BACKGROUND OF THE INVENTION

The market for acidified white cheeses such as FETA cast in canisters, retail cups or cartons is expanding rapidly. These cheeses are usually salted by NaCI to a salt content in the final product around 2.5 to 3.5 %. When casting takes place in containers which are closed before coagulation of the retentate/mix produced from milk protein, vegetable- or animal fat and water, the three ingredients NaCI, GDL and rennet should all be in the retentate/mix produced form milk protein, vegetable- or animal fat and water to be filled. FIG.2 illustrates schematically a batch process in plants working according to the prior art. Pasteurized, homogenized retentate/mix produced from milk protein, vegetable- and/or animal fat and water is through pipeline 27 led to one of the two tanks 28 which are equipped with agitators 29, manholes 30 in the tank tops through which the sacs with NaCI are emptied into the retentate/mix produced from milk protein, vegetable- and/or animal fat and water. The tanks have pressure transmitters 31 for determining and controlling the quantities filled into the tanks. When the desired quantity has been led into the first tank the flow from pipeline 27 is diverted to the other tank and the NaCI is mixed into the product in the first tank, following that the product is ready to have GDL mixed in. Pump 32 will transfer product to the upper tank 33 in the GDL mixing unit, the quantity is controlled by pressure transmitter 34, GDL is dumped to the product through manhole 35 and is mixed into the product by agitator 36. During this operation the valve 37 in the pipeline between the upper tank 33 and the lower tank 38 has been closed. After mixing in the GDL the product can be transferred to the lower tank by opening valve 37. From the lower tank pump 39 will pump the product towards the filling machine 40, the pressure in the discharge line from pump 39 is via a frequency converter on the pump motor controlled by the pressure transmitter 41. Pipeline 42 comes from a container with a rennet solution and pump 43 will controlled by flow transmitter 44 feed a given quantity of rennet solution into the product through injection valve 45.

A problem by producing with GDL is that acidification takes place very fast after the GDL is mixed into the retentate/mix produced from milk protein, vegetable- and/or animal fat and water, and if filling is not completed within ten minutes, the product will start to coagulate. Stops can occur in all types of filling machines and for that reason the GDL mixing units are equipped with water flushing

connections, flushing all product mixed with GDL out of the system with a stop of the filling machine. For a plant with an hourly filling capacity of 2000 litres it can easily mean a loss of 300 litres of retentate which corresponds to approximately 1500 litres of whole milk.

SUMMARY OF THE INVENTION

A first stream of UF retentate and/or mix produced from milk protein, vegetable- and/or animal fat and water is mixed with NaCI and GDL in a mixer and fed to a tank where air is removed and the weight of the contents of the tank is determined.

UF retentate as used herein is used in a manner being ordinary to a skilled person so as to refer to a retentate from ultrafiltrated milk.

Rennet as used herein is used in manner being ordinary to a skilled person and is preferably a complex of enzymes produced in stomachs of ruminant mammals and typically used in the production of most cheeses. Rennet comprising chymosin as a key component and which is a protease enzyme that curdles the casein in milk. In addition to chymosin, rennet contains may preferably comprise other important enzymes such as pepsin and a lipase. There are non-animal sources for rennet that are suitable for consumption by vegetarians. The content of the tank is recirculated to the mixer. A second stream

corresponding to the first stream with added NaCI and GDL is extracted from the tank so that the mass of the mixed stream in the tank is kept within

predetermined limits, and rennet is added to the second stream before it is filled into containers which may be closed and sealed before coagulation takes place.

In the present invention this is done in an in-line continuous process substituting the batch systems used in existing plants. The system in the present invention mixes NaCI and GDL in a powder dosing mixing unit followed by a vacuum unit for removal of air mixed into the product. Final dosing of rennet solution is in the line to the filling machine. Compared to equipment according to the prior art, the system of the invention takes up much less floor space in the dairy, it requires less water, steam and chemicals for CIP, less electrical power for operation and CIP. In comparison to the known batch production systems the system of the invention will have much less volume of process mass to be flushed out and possibly discarded in case of an unplanned stop.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. l shows a preferred embodiment of the invention,

FIG.2 is a schematic process flow of a plant according to the prior art

DETAILED DESCRIPTION OF THE INVENTION

FIG 1 shows a process flow in a system according to the invention. UF retentate and/or mix produced from milk protein, vegetable- and/or animal fat and water is supplied through pipe 1 and fed to the system with pump 2. The capacity of the pump is controlled by flow transmitter 3. 4 is a powder mixer above which are mounted two funnels, one funnel 5 for NaCI and one funnel 6 for GDL. Below the funnels 5, 6 is installed a powder dosing unit 7 with individual regulation of the dosing quantities for NaCI and GDL.

Discharge from the powder mixer is via a flexible hose 8 led in a tangential direction into a vacuum tank 9 which is mounted on a weighing cell 10. The outlet from tank 9 is by a flexible hose 11 connected to the inlet of a circulation pump 12 which through pipe 13 is recirculating the product back to the inlet of the powder mixer 4 at high speed. The flexible hoses 8, 11 ensure that no forces are transmitted to the vacuum tank 9 so that the weighing cell 10 gives reliable data.

In the recirculation circuit from powder mixer 4 over tank 9 and via pump 12 back to powder mixer 4 is inserted a T-junction 14 after pump 12. The T-junction 14 has a branch to an automatic valve 15. Data from the weighing cell 10 control the operation of valve 15 so that the weight of tank 9 is maintained constant by discharging the same weight of mixed product which is introduced to the circulation circuit by pump 2 and the NaCI and GDL dosing.

After valve 15 a rennet solution injector 16 is installed in the pipe line 17 to the filling machine. Rennet solution is dosed by a pump 18 whose capacity is controlled by data from a flow transmitter 19. Should a stop occur e.g. on the filling machine 25 requiring flushing out the product mixed with GDL pump 2 will stop, valve 20 will open towards valve 21 which will open for the water pipe 22. Valve 23 at the pipe 24 to the filling machine will open towards drain or to a collecting vat. Only a small quantity of product is involved in the recirculation process and production can rapidly be resumed following a possible stop. After final production CIP of the unit is done by connecting pipe 1 to the CIP forward line and connecting the filling machines CIP return line to the central CIP station in the dairy.