METHOD FOR ADJUSTING THE DRY MATTER CONTENT OF CONCENTRATES IN CURD PRODUCTION AND DEVICE FOR CARRYING OUT THE METHOD

Abstract

A method for adjusting the dry matter content in curd involves feeding the starting product into a nozzle separator of the device via a feed line while determining a content of dry matter and/or protein, and measuring the mass flow of the starting product. The starting product is centrifugally separated by the nozzle separator into a whey fraction and a curd fraction. The whey fraction and the curd fraction are separately discharged from the nozzle separator and the mass flow of the whey fraction is measured. The mass flow rate of supplied starting product is adjust as a function of the determined content of dry matter or protein of the starting product, the measure mass flow of the starting product, and the measured mass flow of the whey fraction. A determination of the dry matter content and/or the protein content of the curd fraction is carried out on the basis of the determined mass flow of the starting product and the mass flow of the whey fraction and the determined dry matter content and/or protein content of the starting product.

Claims

1. A method for adjusting a dry matter content in curd in a device for centrifugally separating a starting product into the curd and whey, wherein the device comprises a nozzle separator, and wherein the method comprises: a. feeding the starting product into the nozzle separator of the device via a feed line while determining a content of dry matter or protein of the starting product, and measuring a mass flow of the starting product; b. centrifugally separating the starting product by the nozzle separator into a whey fraction and a curd fraction; c. separately discharging the whey fraction and the curd fraction from the nozzle separator and measuring a mass flow of the whey fraction discharged from the nozzle separator; and d. adjusting the mass flow of the starting product as a function of the determined content of dry matter or protein of the starting product, the measure mass flow of the starting product, and the measured mass flow of the whey fraction, wherein a determination of the dry matter content or the protein content of the curd fraction is performed based on the measured mass flow of the starting product, the measured mass flow of the whey fraction discharged from the nozzle separator, and the determined dry matter content or protein content of the starting product.

2. The method of claim 1, further comprising: determining a mass flow of the curd fraction in a discharge line based on the measured mass flow of the starting product and the measured mass flow of the whey fraction.

3. The method of claim 1, wherein a time difference between the measurement of the content of dry matter content or protein of the starting product and the adjustment of the mass flow rate of the starting product is less than 2 min.

4. The method of claim 2, wherein the mass flows of the starting product introduced into the nozzle separator and of the whey fraction discharged from the nozzle separator are continuously measured, the mass flow of the curd fraction in the discharge line is calculated based on the continuous measurements of the mass flows of the starting product introduced into the nozzle separator and of the whey fraction discharged from the nozzle separator, and wherein the determined mass flow of the curd fraction in the discharge line is used as a value for determining a manipulated variable for automatic and continuous regulation of a feed quantity of the starting product.

5. The method of claim 1, wherein the starting product is continuously fed to the nozzle separator during curd production and the whey and curd fractions are continuously discharged.

6. The method of claim 1, wherein the adjustment of the mass flow of the starting product is based on an assumption of a constant dry matter content of whey and that the dry matter of the starting product varies.

7. The method of claim 1, wherein a dry matter content of the whey is measured and used for determining the adjustment of the mass flow of the starting product.

8. The method of claim 2, further comprising: determining a clogging or a degree of clogging of nozzles of the nozzle separator based on the determined mass flow of the curd fraction.

9. A device for producing curd from a starting product, the device comprising: a nozzle separator configured to be fed the starting product, to centrifugally separate the starting product into a whey fraction and a curd fraction, and separately discharge the whey and curd fractions; and a control or evaluation unit configured to determine a content of dry matter or protein of the starting product, measuring a mass flow of the starting product, measuring a mass flow of the whey fraction discharged from the nozzle separator, and adjust the mass flow of the starting product as a function of the determined content of dry matter or protein of the starting product, the measure mass flow of the starting product, and the measured mass flow of the whey fraction, wherein a determination of a dry matter content or the protein content of the curd fraction is performed based on the measured mass flow of the starting product, the measured mass flow of the whey fraction discharged from the nozzle separator, and the determined dry matter content or protein content of the starting product.

10. The device comprises of claim 9, further comprising: a feed line for feeding the starting product into the nozzle separator); a first discharge line for discharging the whey fraction from the nozzle separator; and a second discharge line for discharging the curd fraction from the nozzle separator.

11. The device of claim 10, further comprising: a Coriolis flowmeter that measures the mass flow of the whey fraction, wherein at least one measuring sensor of the Coriolis flowmeter is arranged in or along the first discharge line.

12. The device of claim 11, further comprising: a second Coriolis flowmeter that measures the mass flow of the starting product, wherein at least one measuring sensor of the second Coriolis flowmeter is arranged in or along the feed line.

13. The device of claim 12, further comprising: a measuring device, which has a measuring sensor configured to emit and receive electromagnetic radiation to measure the dry matter content or the protein content of the curd fraction, wherein at least the measuring sensor of the measuring device is arranged in or along the feed line.

14. The device of claim 10, further comprising: a regulating valve configured to adjust the mass flow of the starting product, wherein the regulating valve is arranged along the feed line.

Description

BRIEF DESCRIPTION OF THE DRAWING FIGURES

[0036] Further advantages, features and details of the invention will be apparent from the following description, in which an exemplary embodiment of the invention is explained in more detail with reference to the accompanying drawings. The person skilled in the art will expediently also consider the features disclosed in combination in the drawing, the description and the claims individually and combine them to form useful further combinations. In particular, there are a multitude of possibilities for modifying and further developing the method for adjusting the dry matter content according to the invention within the scope of the present invention, wherein:

[0037] FIG. 1 shows a schematic illustration of a device with a nozzle separator for carrying out the method according to the invention; and

[0038] FIG. 2 shows a block diagram of the process sequence of the method according to the invention.

DETAILED DESCRIPTION

[0039] The dry mass of the produced concentrate of curd Q (hereinafter DM3) is largely dependent on the fluctuating dry mass (DM1) of the starting product A and the mass flow of the light whey phase M with an approximately constant dry mass content DM.2

[0040] Another factor that can have a certain influence on the setting of the dry matter content is the nozzle equipment of the separator, which is, however, constant during the running process. However, clogging of the nozzles or a reduction of the nozzle diameter can have a certain effect.

[0041] Clogging of nozzles can be detected by the method according to the invention, because in such a case the mass flow {dot over (m)}3 of the curd would decrease proportionally to the number of clogged nozzles.

[0042] The feed quantity is the only parameter that can be actively influenced during production to affect the DM3 of the curd. The rule of thumb is that a larger feed quantity results in a higher DM of the curd concentrate.

[0043] For the adjustment, in particular for the regulation of the dry matter in the curd concentrate, the suitable feed quantity can be calculated based on the mass balance (Formula 1) and accounting for the theoretical throughputs of the nozzles. For this purpose, the difference between the target dry matter DM3, expressed here as C.sub.concentrate, and the approximately constant dry matter DM2 of the whey, expressed here as C.sub.whey, is related to the difference between the dry matter DM1 of the starting product used, e.g., skim milk or tank milk, expressed here as C.sub.starting material, and the dry matter DM2 of the whey, which is then multiplied by the nozzle throughput.

[0044] This calculation is based on the assumption of knowing the exact nozzle flow rate. Practice has shown that this procedure gives a good initial indicator of the required feed rate, but this usually has to be adjusted after sampling the curd.

[00001]$\begin{array}{cc}{\dot{m}}_{\mathrm{feed}}={\dot{m}}_{nozzles}*\frac{c_{concentrate}-c_{whey}}{c_{\mathrm{startingproduct}}-c_{whey}}& \left(\mathrm{Formula}1\right)\end{array}$

[0045] The method described below and the correspondingly designed device compensate for the uncertainty of the unknown nozzle flow rate by measuring it via the difference between the mass flows of the starting product to the separator and the whey. For this purpose, mass flow meters are used in the feed and discharge of the whey (see FIG. 1). The nozzle discharge is calculated using (Formula 2), taking into account that the measured values should be smoothed for preferably approx. 60 seconds in order to be able to determine a nozzle discharge that is as constant as possible.

{dot over (m)}.sub.nozzles={dot over (m)}.sub.feed−{dot over (m)}.sub.whey  (Formula 2)

[0046] The dashes within the formula indicate the smoothing or the averaging over a certain period of time, e.g., 60 seconds. Corresponding designations for the specification of mean values are known in the art.

[0047] The exemplary embodiment example shown in FIG. 1 schematically illustrates a device with a nozzle separator 3, preferably with a disc stack (not shown in detail), and with a rotatably mounted bowl (also not shown in detail), which has a bowl volume. The bowl may have a vertical axis of rotation. The separator 3 has a bowl volume. This bowl volume results from the design-related specifications of the separator 3 and at the same time defines a dead time.

[0048] The device 10 has a feed line 1 to the nozzle separator 3, along which a regulating element 2 is arranged. A flow meter 9 is also arranged along the feed line 1.

[0049] A starting product A, preferably skim milk or curdled tank milk, is fed into the nozzle separator 3, in which the starting product is separated into whey M as a liquid phase and curd Q as a (solid) concentrate. While the whey is discharged from the nozzle separator 3 via the discharge line 4, the concentrate Q is discharged via nozzles through the discharge line 5. The discharge of the concentrate can be continuous. The concentrate Q can then be further processed and cooled, for example.

[0050] In the device according to the invention, a flow meter 8, or at least the measuring sensor of a flow meter, is arranged in or along the discharge line 4 of the whey M. The flow rate of the whey M from the nozzle separator 3 can be determined, for example, as a mass flow. The measured values recorded by the flow sensors 8 and 9 and the measured value of the measuring device 6 for determining the dry matter content are transmitted directly via the signal lines 11, 13, 14 to a control and/or evaluation unit 7, where the measured flow value is used as a control variable to determine a manipulated variable S, which is used to adjust the regulating element 2 via a signal line 12 between the control and/or evaluation unit 7 and the regulating element 2.

[0051] The adjustment of the dry matter content according to the present method is carried out in such a way that the flow rate, in particular the mass flow rate or mass flow, of whey M in the discharge line 4 of the light phase is determined. In curd production, the light phase is the whey. Due to the separation in the separator, the whey M always has approximately the same dry matter content and can therefore be assumed to be constant.

[0052] In addition, the mass flow in the feed line is determined. This also varies with the dry matter content of the starting product. Since the fed starting product may have a dry matter content that varies greatly in some cases, the concentrate will also have a correspondingly varying dry matter content. The operation of the separator and the feed quantity must be adjusted accordingly by the control and/or evaluation unit.

[0053] If, for example, a starting product with too little dry matter is fed to the separator 3, the regulating element 2, e.g., a regulating valve, must be opened further so that more dry matter enters the separator and a sufficient amount of concentrate Q is in front of the nozzles of the separator.

[0054] By means of a regulated, automatic increase and decrease of the feed capacity of the nozzle separator depending on the flow balance of the fed starting product and the discharged whey, an adjustment to the desired dry matter is made for the curd. A higher feed rate causes an increase in dry matter and vice versa.

[0055] Suitable measuring devices, especially for determining the mass flow of the starting product and whey are Coriolis flow meters. It is also possible to use a combination of volumetric flow meter and density meter to determine a mass flow, although these are less preferred.

[0056] In addition, a sensor can be arranged in the feed of the starting product A as a measuring sensor of a measuring device 6 for determining the dry matter content of the starting product. Such a sensor can be, for example, a sensor based on a measurement of electromagnetic waves. Corresponding sensors for moisture measurement are, for example, microwave measuring devices, infrared measuring devices, UV-vis measuring devices and the like. In particular, the FT 120 or FT 1 measuring devices from Foss GmbH for liquid products should also be mentioned here. Preferably, the corresponding sensor for the present application is part of an in-line measuring device. The use of an in-line measuring technique for direct determination of the current process conditions enables direct regulation. The requirements for this are ±0.1% measurement accuracy for dry matter. Possible devices for this are the microwave measurement from Berthold and ProFoss.

[0057] A measurement of the dry matter especially in the feed milk in combination with the previously described system allows automatic process control for different (concentrated) skim milk batches. Measuring the dry matter of the feed milk also eliminates the dead time until the new concentration is set. This measurement in the feed to the separator is also useful, as the dry matter there may well fluctuate (e.g., due to sedimentation in the tank, tank change, etc.).

[0058] FIG. 2 again shows the step sequence of a variant of the method according to the invention for regulating the dry matter content of concentrates in the production of curd cheese, in particular in the production of cottage cheese by means of the device shown in FIG. 1.

[0059] In a first step 101, a starting product A is fed to the nozzle separator 3 of the device 10. This is carried out via the feed line 1 shown in FIG. 1.

[0060] In this process, the mass flow {dot over (m)}1 of the fed starting product A and the dry mass content DM1 of the starting product are determined.

[0061] In the nozzle separator 3, in a second step 102, separation takes place into an aqueous light phase, the whey M, and a solid concentrate Q, the curd, which, relative to the whey M, represents the heavy or heavier phase.

[0062] In a third step 103, the separated phases M and Q are discharged from the separating device by means of separate discharge lines 4 and 5 measuring the mass flow {dot over (m)}2 of the light phase, i.e., whey M.

[0063] Based on the determined dry matter content DM1 and depending on the measured mass flow rates {dot over (m)}1 and {dot over (m)}2, in a fourth step 104 the control and/or evaluation unit 7 adjusts the feed quantity of starting product by generating a control signal S and ultimately thereby also adjusts the dry matter content DM3 in the solids concentrate Q, i.e., the curd.

[0064] The measurement is preferably carried out continuously and also preferably with the aid of mass flow meters in each case in the feed line 1 and in a discharge line 4 from the nozzle separator.

[0065] The determined dry matter content of the starting product A serves as a controlled variable for setting a suitable mass feed {dot over (m)}1 of starting product A as a function of the amount of discharging whey M, whereby an intended dry matter content DM3 in the solids concentrate Q can be set.

[0066] From the mass flows of the starting product {dot over (m)}1 and the whey {dot over (m)}2, the mass flow {dot over (m)}3 of curd Q in the discharge line 5 can be calculated, and the dry mass DM3 of the curd can be calculated by means of the determined dry mass DM1 of the starting product A and if the dry mass DM2 of the whey M is known and essentially constant. This determined mass flow {dot over (m)}3 in the discharge line 5 can be used as a controlled variable for determining a manipulated variable S for continuous and automatic regulation of the feed quantity of the starting product.

[0067] Alternatively, or for redundancy, the dry matter content of the whey can also be measured and used in the determination in step d.

[0068] With reference to EP 0 440 208 B1, the present case involves a completely different machine, which has a different separation characteristic.

[0069] This process control means that there is no significant dead time and a concentration deviation in the end product is counteracted in advance.

[0070] Monitoring of the nozzle wear via the increase in the determined discharge quantity {dot over (m)}3 of the nozzles is possible and an indication for a necessary nozzle exchange can be generated.

[0071] A reduction in the determined nozzle discharge {dot over (m)}3 during production can also be an indicator of a blocked nozzle. Here, for example, a change of

[00002]$\Delta {\dot{m}}_{nozzles}>\frac{1}{12}\stackrel{\_}{{\dot{m}}_{nozzles}}$

would be a possible limit value.

[0072] Instead of or in addition to the dry mass, the mass of the protein can also be measured inline. The mass balance is also valid for protein, thus the standardization of the concentrate would also be possible for protein.

LIST OF REFERENCE SIGNS

[0073] 1 Feed line [0074] 2 Regulating element [0075] 3 Nozzle separator [0076] 4 Discharge line (whey) [0077] 5 Discharge line (curd) [0078] 6 Measuring device (determination of dry matter content) [0079] 7 Control and/or evaluation unit [0080] 8 Flow meter [0081] 9 Flow meter [0082] 10 Device [0083] 11 Signal line [0084] 12 Signal line [0085] 13 Signal line [0086] 14 Signal line [0087] DM1 Dry matter content of starting product [0088] DM2 Dry matter content of whey [0089] DM3 Dry matter content of curd [0090] {dot over (m)}1 Mass flow or flow rate of the starting product [0091] {dot over (m)}2 Mass flow or flow rate of the whey fraction [0092] {dot over (m)}3 Mass flow or flow rate of the curd fraction [0093] A Starting product [0094] Q Solid concentrate (curd) [0095] M Whey [0096] S Manipulated variable [0097] 101 First step (feeding+measuring−starting product) [0098] 102 Second step (separation of fractions) [0099] 103 Third step (measuring—whey) [0100] 104 Fourth step (determination of DM content—curd)