A raw milk concentration system

Abstract

This invention discloses a raw milk concentration system, comprising: a raw milk storage tank, a pre-filtration device, a nanofiltration device, a multi-stage ultrafiltration device, and a concentrated raw milk storage tank, connected sequentially by pipelines; the multi-stage ultrafiltration device consists of several sub-ultrafiltration devices connected sequentially, each sub-ultrafiltration device being equipped with an ultrafiltration membrane, and the molecular weight cutoff of the ultrafiltration membranes decreasing sequentially among the sequentially connected sub-ultrafiltration devices. This invention enables the direct concentration and separation of raw milk through pre-filtration, nanofiltration, and multi-stage ultrafiltration to obtain concentrated raw milk with low lactose and high protein content.

Description

Technical Field

[0001] The utility model relates to the technical field of deep processing of dairy products, and particularly relates to a concentration system for low-lactose and high-protein raw milk. Background Art

[0002] Since high-protein milk was launched on the market, it has taken high-protein nutrition as the main selling point and has won the unanimous recognition and praise of consumers. There have emerged many high-protein milk products on the market. However, from the perspective of the concentration process, these products all require relatively complex pretreatment processes, mainly separation and homogenization. The raw milk is defatted, and after concentration, diluted cream is used for backfilling to obtain low-lactose and high-protein milk products. And the true protein content of this low-lactose and high-protein milk product is generally below 6%. If a high-protein product with a protein content above 6% is to be obtained, protein powder and other food additives need to be added. Therefore, there is an urgent need to develop a method for directly producing low-lactose and high-protein products using raw milk, which can simplify the cumbersome process flow and achieve the effect of low-lactose and high-protein without adding protein powder and food additives additionally. Content of the Utility Model

[0003] The purpose of the utility model is to provide a raw milk concentration system, so that raw milk can be directly concentrated and separated into low-lactose and high-protein concentrated raw milk through pre-filtration, nanofiltration and multi-stage ultrafiltration. To achieve the above purpose, the utility model adopts the following technical solutions: The utility model discloses a raw milk concentration system, including: a raw milk storage tank, a pre-filtration device, a nanofiltration device, a multi-stage ultrafiltration device and a concentrated raw milk storage tank, which are connected in sequence through pipelines.

[0004] The multi-stage ultrafiltration device consists of a number of sub-ultrafiltration devices connected in sequence. An ultrafiltration membrane is provided in the sub-ultrafiltration device, and in a number of sub-ultrafiltration devices connected in sequence, the cut-off molecular weight of the ultrafiltration membrane decreases in sequence.

[0005] Among them, the multi-stage ultrafiltration device is a three-stage ultrafiltration device, including three sub-ultrafiltration devices connected in sequence, namely a first-stage ultrafiltration device, a second-stage ultrafiltration device and a third-stage ultrafiltration device.

[0006] Preferably, the cut-off molecular weights of the ultrafiltration membranes in the first-stage ultrafiltration device, the second-stage ultrafiltration device and the third-stage ultrafiltration device are a, b, and c respectively, and 5000 ≤ c < b < a ≤ 20000 Da. And the pressures in the first-stage ultrafiltration device, the second-stage ultrafiltration device and the third-stage ultrafiltration device are e, f, and g respectively, 0.5 ≤ e < f < g ≤ 8 Bar.

[0007] Furthermore, a pre-filtration membrane is provided in the pre-filtration device, and the pore diameter of the pre-filtration membrane is h, h ≤ 10 μm.

[0008] Furthermore, the nanofiltration device is equipped with a nanofiltration membrane, the nanofiltration membrane having a molecular weight cutoff of i, and 200≤i≤800 Da. The pressure in the nanofiltration device is j, and 5≤j≤20 Bar.

[0009] Furthermore, a primary feed pump is installed between the pre-filtration device and the nanofiltration device.

[0010] Furthermore, a two-stage feed pump is installed between the nanofiltration device and the multi-stage ultrafiltration device.

[0011] Preferably, the raw milk concentration system further includes a nanofiltration dialysate storage tank, which is connected to the nanofiltration device to receive the dialysate.

[0012] In some other embodiments, the raw milk concentration system further includes a water recovery system connected to the nanofiltration device to directly recover and process the nanofiltration dialysis solution.

[0013] Preferably, the raw milk concentration system further includes an ultrafiltration dialysate storage tank, which is connected to the sub-ultrafiltration devices in the multi-stage ultrafiltration device to receive ultrafiltration dialysates from each stage.

[0014] After adopting the above technical solution, the present invention has the following effects: This invention, through optimized system design, allows raw milk to be directly concentrated and separated into low-lactose, high-protein concentrated milk via pre-filtration, nanofiltration, and multi-stage ultrafiltration. After subsequent homogenization and sterilization, the concentrated milk can be directly bottled or used to prepare high-protein yogurt. Simultaneously, the dialysis liquid after membrane filtration is recovered and treated, enabling its use in the preparation of other products. This high recovery rate significantly reduces production costs. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of a system according to Embodiment 1 of this utility model.

[0016] Figure 2 This is a schematic diagram of the system in Embodiment 2 of this utility model.

[0017] Figure 3 This is a process flow diagram of the present invention.

[0018] Main component symbols: 1: Raw milk storage tank; 2: Pre-filtration device; 3: Nanofiltration device; 4: Multi-stage ultrafiltration device; 41: Primary ultrafiltration device; 42: Secondary ultrafiltration device; 43: Tertiary ultrafiltration device; 5: Nanofiltration dialysate storage tank; 6: Ultrafiltration dialysate storage tank; 7: Concentrated raw milk storage tank; 8: Water recovery system; 9: Primary feed pump; 10: Secondary feed pump. Detailed implementation manners

[0019] In order to make the objectives, technical solutions and advantages of the present utility model clearer and more understandable, the present utility model will be further described in detail below with reference to the drawings and embodiments.

[0020] As Figure 1 shown, the present utility model discloses a raw milk concentration system, including: a raw milk storage tank 1, a pre-filtering device 2, a nanofiltration device 3, a multi-stage ultrafiltration device 4 and a concentrated raw milk storage tank 7, which are connected in sequence through pipelines. In this embodiment, a first-stage feed pump 9 is installed between the pre-filtering device 2 and the nanofiltration device 3, and a second-stage feed pump 10 is installed between the nanofiltration device 3 and the multi-stage ultrafiltration device 4.

[0021] The multi-stage ultrafiltration device 4 is composed of a number of sub-ultrafiltration devices connected in sequence. Ultrafiltration membranes are provided in the sub-ultrafiltration devices, and in the number of sub-ultrafiltration devices connected in sequence, the molecular weight cut-off of the ultrafiltration membranes decreases in sequence.

[0022] In this embodiment, the multi-stage ultrafiltration device 4 is a three-stage ultrafiltration device, including three sub-ultrafiltration devices connected in sequence, namely a first-stage ultrafiltration device 41, a second-stage ultrafiltration device 42 and a third-stage ultrafiltration device 43. In some other embodiments, according to the molecular weight cut-off of the ultrafiltration membranes and the different degrees of raw milk concentration, ultrafiltration devices with more than three stages can also be set. However, for ordinary concentrated raw milk, three-stage ultrafiltration can already meet the requirements, and there is no need to set ultrafiltration devices with more than three stages to increase the production cost of the product.

[0023] Among them, the molecular weight cut-off of the ultrafiltration membranes in the first-stage ultrafiltration device 41, the second-stage ultrafiltration device 42 and the third-stage ultrafiltration device 43 are a, b, c respectively, and 5000 ≤ c < b < a ≤ 20000 Da. And the pressures in the first-stage ultrafiltration device 41, the second-stage ultrafiltration device 42 and the third-stage ultrafiltration device 43 are e, f, g respectively, 0.5 ≤ e < f < g ≤ 8 Bar.

[0024] Secondly, in this embodiment, a pre-filtering membrane is provided in the pre-filtering device 2, the pore diameter of the pre-filtering membrane is h, and h ≤ 10 μm. A nanofiltration membrane is provided in the nanofiltration device 3, the molecular weight cut-off of the nanofiltration membrane is i, and 200 ≤ i ≤ 800 Da. And the pressure in the nanofiltration device 3 is j, 5 ≤ j ≤ 20 Bar.

[0025] In addition, in this embodiment, the raw milk concentration system further includes: a nanofiltration dialysis liquid storage tank 5 and an ultrafiltration dialysis liquid storage tank 6.

[0026] The nanofiltration dialysis liquid storage tank 5 is connected to the nanofiltration device 3 to receive the nanofiltration dialysis liquid. After the nanofiltration dialysis liquid is collected, it is processed by an external water recovery system and used as batching or cleaning water. As Figure 2As shown, in some embodiments, the raw milk concentration system includes a water recovery system 8, which is directly connected to the nanofiltration device 3, that is, it directly processes the nanofiltration dialysate without the need to set up a nanofiltration dialysate storage tank 5 for storage.

[0027] The ultrafiltration dialysis fluid storage tank 6 is connected to the primary ultrafiltration unit 41, the secondary ultrafiltration unit 42 and the tertiary ultrafiltration unit 43 respectively to receive the ultrafiltration dialysis fluid from each stage. After collection, the ultrafiltration dialysis fluid can be used as an ingredient or processed into lactose powder after further treatment.

[0028] like Figure 3 As shown, the process for raw milk concentration and extraction using this invention includes the following steps: S1. Pre-filtration: The raw milk is passed through pre-filtration device 2 to remove hair, fat clumps, fat particles, and other impurities. Pre-filtration device 2 typically includes three processes: coarse filtration, medium filtration, and fine filtration. In coarse filtration, a dual-stage filter is commonly used to remove large particles, with an internal nylon or polyester mesh filter bag with a pore size of 100-200 μm. In medium filtration, a spiral wound microfilter is commonly used to remove medium-sized suspended solids, with an internal polypropylene membrane with a pore size of 50 μm. In fine filtration, a pre-filtration membrane with a pore size of 5-10 μm is commonly used for pretreatment before membrane separation, minimizing membrane fouling in subsequent nanofiltration and ultrafiltration processes. The table below shows the component content of the raw milk after pre-filtration:

[0029] S2. Nanofiltration: The pre-filtered raw milk from step S1 is passed through nanofiltration device 3 at a pressure of 10 Bar through a nanofiltration membrane with a molecular weight cutoff of 500 Da to separate the low-concentration raw milk concentrate, yielding nanofiltration dialysis solution. The table below shows the content of each component in the pre-filtered raw milk after nanofiltration:

[0030] S3. First-stage ultrafiltration: The low-concentration raw milk concentrate obtained from nanofiltration in step S2 is passed through a first-stage ultrafiltration device 41 at a pressure of 0.5 Bar through an ultrafiltration membrane with a molecular weight cutoff of 20,000 Da to separate the first-stage ultrafiltration concentrate, yielding the first-stage ultrafiltration dialysate. The table below shows the composition of each component in the low-concentration raw milk concentrate after first-stage ultrafiltration:

[0031] S4. Secondary Ultrafiltration: The primary ultrafiltration concentrate from step S3 is passed through a secondary ultrafiltration device 42 at a pressure of 1.5 Bar through an ultrafiltration membrane with a molecular weight cutoff of 10000 Da to separate the secondary ultrafiltration concentrate, yielding the secondary ultrafiltration dialysate. The table below shows the composition of each component in the primary ultrafiltration concentrate after secondary ultrafiltration:

[0032] S5. Tertiary Ultrafiltration: The secondary ultrafiltration concentrate from step S4 is passed through a tertiary ultrafiltration device 43 to separate the tertiary ultrafiltration concentrate and obtain tertiary ultrafiltration dialysate. By controlling the pressure in the tertiary ultrafiltration device 43 and the molecular weight cutoff of the ultrafiltration membrane, low-lactose, high-protein raw milk with varying content can be obtained.

[0033] The table below shows the component content of 8% low-lactose, high-protein raw milk obtained after tertiary ultrafiltration of the secondary ultrafiltration concentrate (pressure 4 Bar, ultrafiltration membrane molecular weight cutoff 9000 Da):

[0034] The table below shows the component content of 12.5% ​​low-lactose, high-protein raw milk obtained after tertiary ultrafiltration of the secondary ultrafiltration concentrate (pressure 6 Bar, ultrafiltration membrane molecular weight cutoff 6000 Da):

[0035] The table below shows the component content of 15% low-lactose, high-protein raw milk obtained after tertiary ultrafiltration of the secondary ultrafiltration concentrate (pressure 8 Bar, ultrafiltration membrane molecular weight cutoff 5000 Da):

[0036] The above description is only a preferred embodiment of the present utility model. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present utility model should be included within the protection scope of the present utility model.

Claims

1. A raw milk concentration system, characterized in that, include: The raw milk storage tank, pre-filtration device, nanofiltration device, multi-stage ultrafiltration device and concentrated raw milk storage tank are connected in sequence by pipelines. The multi-stage ultrafiltration device consists of several sub-ultrafiltration devices connected in sequence. Each sub-ultrafiltration device is equipped with an ultrafiltration membrane, and the molecular weight cutoff of the ultrafiltration membrane decreases sequentially among the several sub-ultrafiltration devices connected in sequence.

2. The raw milk concentration system as described in claim 1, characterized in that: The multi-stage ultrafiltration device is a three-stage ultrafiltration device, comprising three sub-ultrafiltration devices connected in sequence, namely a primary ultrafiltration device, a secondary ultrafiltration device, and a tertiary ultrafiltration device.

3. The raw milk concentration system as described in claim 2, characterized in that: The molecular weight cutoffs of the ultrafiltration membranes in the primary, secondary, and tertiary ultrafiltration devices are a, b, and c, respectively, and 5000 ≤ c. <b<a≤20000 Da; Furthermore, the pressures in the primary, secondary, and tertiary ultrafiltration devices are e, f, and g, respectively, where 0.5 ≤ e. <f<g≤8 Bar。 4. The raw milk concentration system as described in claim 1, characterized in that: The pre-filtration device is equipped with a pre-filtration membrane, the pore size of which is h, h≤10 μm.

5. The raw milk concentration system as described in claim 1, characterized in that: The nanofiltration device is equipped with a nanofiltration membrane, the nanofiltration membrane has a molecular weight cutoff of i, and 200≤i≤800 Da; Furthermore, the pressure in the nanofiltration device is j, where 5 ≤ j ≤ 20 Bar.

6. The raw milk concentration system as described in claim 1, characterized in that: A primary feed pump is installed between the pre-filtration device and the nanofiltration device.

7. The raw milk concentration system as described in claim 1, characterized in that: A two-stage feed pump is installed between the nanofiltration device and the multi-stage ultrafiltration device.

8. A raw milk concentration system as described in any one of claims 1-7, characterized in that: Also includes: A nanofiltration dialysate storage tank, which is connected to the nanofiltration device, is used to receive the dialysate.

9. A raw milk concentration system according to any one of claims 1-7, characterized in that: Also includes: A water recycling system is connected to the nanofiltration device to directly recycle and process the nanofiltration dialysis solution.

10. A raw milk concentration system according to any one of claims 1-7, characterized in that: Also includes: Ultrafiltration dialysate storage tanks are connected to sub-ultrafiltration units in the multi-stage ultrafiltration device to receive ultrafiltration dialysate from each stage.

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