Lactose-free whey protein concentrates

Abstract

Proposed are whey protein concentrates (MPK2) obtained or obtainable by the following steps: a) provision of a whey source (M); b) ultrafiltration of the whey (M) from step (a) to obtain a first permeate (P1) and a first retentate (R1); c) ultrafiltration of the first retentate (R1) from step (b) to obtain a second permeate (P2) and a second retentate (R2); d) dewatering of the second retentate (R2) from step (c) to obtain a lactose-containing whey protein concentrate (MPK1); e) addition of lactase to the second retentate (R2) from step (b) or (c) or to the lactose-containing whey protein concentrate (MPK1) from step (d) to hydrolyze any remaining lactose to obtain a lactose-free whey protein concentrate (MPK2); and optionally (f) spray-drying of the lactose-free whey protein concentrate (MPK2) from step (e).

Description

Lactose-free whey protein concentrates FIELD OF THE INVENTION

[0001] The present invention is in the field of the dairy industry and relates to lactose-free whey protein concentrates and a process for their production. TECHNOLOGICAL BACKGROUND

[0002] Whey is the watery, greenish-yellow residual liquid produced during cheese production. It is the liquid part that can be separated after the milk has curdled to form cheese or curd. Whey consists of 94% water, 4 to 5% lactose, and is virtually fat-free. It also contains lactic acid, vitamins B1, B2 (which gives it its greenish color), and B6, as well as potassium, calcium, phosphorus, and other minerals, but most importantly, 0.6 to 1% by weight of whey protein. Whey contains significantly less protein than milk. In particular, unlike milk, it does not contain casein. Many strength athletes use whey protein in the form of protein powder to build muscle, as whey protein is quickly digested and thus readily available to the body. It is therefore frequently used in pre- and post-workout shakes. The protein-rich whey powder is also used in bakeries, in ready-to-eat food production, and in dairies themselves.

[0003] Whey is therefore an important source of protein for both human and animal nutrition. However, the high lactose content is a disadvantage, which is undesirable in times of widespread lactose intolerance. STATE OF THE ART

[0004] EP 2493325 B1 (VALIO) claims whey proteins obtained by first subjecting a milk starting product to microfiltration, separating the casein fraction as the retentate, then subjecting the permeate to ultrafiltration, thereby obtaining a whey protein concentrate as the retentate, and finally remixing the two retentates. No lactose hydrolysis step is included.

[0005] EP 2773222 A1 (FONTERRA) discloses a process for preparing a solution containing undenatured whey proteins. The process does not involve hydrolysis of the lactose present.

[0006] WO 06068521 A1 (FONTERRA) relates to a process for producing whey protein concentrates, in which a whey protein solution is denatured by heating, cooled, and then sprayed. The process does not involve lactose hydrolysis.

[0007] WO 11046431 A1 (FRIESLAND) teaches a process for producing whey protein concentrates in which acid whey is mixed with carbonates, the mixture is subjected to ultrafiltration, and the carbonate-containing acid whey is sprayed. The process does not involve hydrolysis of the lactose present.

[0008] WO 12121131 A1 (MEIJI) claims a process for producing fermented milk, in which whey powder is dissolved in raw milk and the lactose contained is hydrolyzed by adding lactase. However, no whey protein concentrates are produced. OBJECT OF THE INVENTION

[0009] In the past, separating lactose from whey has proven difficult or even technically impossible. One option would be to use diafiltration with water. To achieve a residual lactose content of less than 0.1% w / w or even less than 0.01% w / w, this would require washing a whey protein concentrate with 80% w / w protein and approximately 15 to 40% w / w dry matter with 8 to 10 times the amount of drinking water that was used as the original concentrate. This would turn valuable drinking water into wastewater, which would generate a high load of wastewater into the sewage treatment plant. For one daily batch, this would mean approximately 500,000 liters of fresh water being converted into 500,000 liters of wastewater. Such a washing process would also require filtration plants 10 to 20 times larger than those currently in use to produce the whey protein concentrate and even carry out the diafiltration.Finally, washing out the lactose would also remove all minerals, meaning the whey protein concentrate with 80% protein by weight would become a completely different product, consisting only of protein and small amounts of fat, and would therefore be more like a whey protein isolate with 95% protein by weight. It is clear that such a process would be impractical given the enormous energy and resource consumption.

[0010] Therefore, the object of the present invention was to provide whey protein concentrates in liquid form or in the form of dry or nearly dry powders by means of a technically easy-to-implement process, which are free of lactose, ie which have a residual amount of lactose of less than 0.1% by weight and in particular less than 0.01% by weight, based on the products. DESCRIPTION OF THE INVENTION

[0011] A first aspect of the invention relates to lactose-free whey protein concentrates (MPK2) obtained or obtainable according to the following steps: (a) providing a whey source (M); (b) ultrafiltration of the whey (M) from step (a) to obtain a first permeate (P1) and a first retentate (R1); (c) ultrafiltration of the first retentate (R1) from step (b) to obtain a second permeate (P2) and a second retentate (R2); (d) dewatering the second retentate (R2) from step (c) to obtain a lactose-containing whey protein concentrate (MPK1); (e) adding lactase to the second retentate (R2) from step (b or c) or to the lactose-containing whey protein concentrate (MPK1) from step (d) with hydrolysis of the lactose still present to obtain a lactose-free whey protein concentrate (MPK2); and optionally (f) spray-drying the lactose-free whey protein concentrate (MPK2) from step (e).

[0012] Also claimed is a corresponding process for producing lactose-free whey protein concentrates (MPK2), comprising or consisting of the following steps: (a) providing a whey source (M); (b) ultrafiltration of the whey (M) from step (a) to obtain a first permeate (P1) and a first retentate (R1); (c) ultrafiltration of the first retentate (R1) from step (b) to obtain a second permeate (P2) and a second retentate (R2); (d) dewatering the second retentate (R2) from step (c) to obtain a lactose-containing whey protein concentrate (MPK1); (e) adding lactase to the second retentate (R2) from step (b or c) or to the lactose-containing whey protein concentrate (MPK1) from step (d) with hydrolysis of the lactose still present to obtain a lactose-free whey protein concentrate (MPK2); and optionally (f) spray-drying the lactose-free whey protein concentrate (MPK2) from step (e).

[0013] In the embodiment according to which two ultrafiltration steps are carried out, these can also be carried out one after the other on one system.

[0014] Surprisingly, it was found that the process according to the invention makes a new product quality of whey protein powders accessible that are virtually free of lactose and therefore particularly suitable for people suffering from lactose intolerance. The process is also technically simple to implement. In particular, the addition of lactase after completion of all filtration and enrichment steps has proven critical, as this is the only way to ensure that the nutritional value of the final product is not reduced. In particular, there is no risk of "losing" simple sugars in the filtration system. The spatially and temporally confined process ensures, in particular, that the enzyme cannot spread to other process components and alter the product quality. Raw materials

[0015] Possible whey sources include, for example, thin whey with a dry matter content of approximately 5 wt.% or whey concentrates with dry matter contents of approximately 30 wt. Preferably, mixtures of the two starting materials ("mixed whey") are used, which have dry matter contents of approximately 5 to approximately 20 wt.%, and in particular of approximately 8 to approximately 12 wt.%. Ultrafiltration

[0016] Ultrafiltration and nanofiltration are filtration processes in the field of membrane technology that can be used to separate and concentrate macromolecular substances and small particles from a medium. Microfiltration, ultrafiltration, and nanofiltration are differentiated by the degree of separation. If the cutoff is 100 nm or higher, the process is called microfiltration. If the cutoff is in the range between 2 and 100 nm, it is called ultrafiltration. In nanofiltration, the cutoff is below 2 nm. In each of these cases, these are purely physical, i.e., mechanical, membrane separation processes that operate according to the principle of mechanical size exclusion: all particles in the fluid that are larger than the membrane pores are retained by the membrane.The driving force in both separation processes is the differential pressure between the inlet and outlet of the filter surface, which is between 0.1 and 10 bar for ultra- and microfiltration and up to approx. 40 bar for nanofiltration.

[0017] The exclusion limits of ultrafiltration membranes are also specified in the form of the NMWC (Nominal Molecular Weight Cut-Off, also MWCO, Molecular Weight Cut-Off, unit: Dalton). This is defined as the minimum molecular mass of globular molecules that are 90% retained by the membrane. In practice, the NMWC should be at least 20% lower than the molecular mass of the molecule to be separated. Further qualitative statements about filtration can be made based on the flux (water value), transmembrane flow, or permeation rate. Ideally, this is proportional to the transmembrane pressure and reciprocal to the membrane resistance. These parameters are determined by the properties of the membrane used, as well as by concentration polarization and any fouling that may occur. The permeation rate is defined as 1 m 2 Membrane area. Its unit is l / (m 2 h bar).

[0018] Membranes with a pore diameter in the range of about 1,000 to about 50,000, and preferably about 5,000 to about 25,000 Daltons have proven particularly suitable for ultrafiltration. Nanofiltration prefers pore diameters in the range of 100 to 2,000, and preferably about 150 to 1,000 Daltons.

[0019] The material of the filter surface – both in ultra- and nanofiltration – can be stainless steel, polymer materials, ceramic, aluminum oxide or textile fabric. There are various forms of filter elements: candle filters, flat membranes, spiral-wound membranes, pocket filters, and hollow-fiber modules, all of which are fundamentally suitable for the purposes of the present invention. However, spiral-wound membranes made of polymer materials or candle filters made of ceramic or aluminum oxide are preferably used, with the first embodiment proving particularly preferred for ultrafiltration and nanofiltration, and the second for microfiltration.

[0020] The cut-off values ​​overlap in the borderline range, so that, for example, a membrane with a pore diameter of about 2,000 Daltons can be suitable for both ultrafiltration and nanofiltration.

[0021] In the context of the process according to the invention, ultrafiltration steps (b) and (c) essentially serve to reduce the water content, separate minerals and the majority of lactose, and enrich the protein content in the dry matter. Typically, the first ultrafiltration in step (b) produces a retentate (R1) having a dry matter content of approximately 10 to approximately 20 wt.%, while the retentate (R2), which is obtained in the second ultrafiltration, has a dry matter content of approximately 20 to approximately 40 wt.%. However, these two ultrafiltration steps can also be combined if necessary.

[0022] Typically, the first and second ultrafiltration in steps (b) and (c) are carried out in the temperature range from about 2 to about 25 °C and in particular from about 5 to about 15 °C and in the pressure range from about 0.1 to about 15 bar, preferably from about 1 to about 10 bar. It has proven advantageous to carry out the second ultrafiltration in step (c) in the presence of drinking water or the permeate of a reverse osmosis system, wherein the dilution in the second ultrafiltration in step (c) can be from about 20 to about 200%, preferably from about 50 to about 150% - based on the feed (R2). drainage

[0023] A further step (d) for dewatering the products follows the second ultrafiltration. This can involve further ultrafiltration, nanofiltration, reverse osmosis, or evaporation, or a combination of the above processes. The ultrafiltration and nanofiltration processes have already been described above.

[0024] Reverse osmosis is a physical membrane process for concentrating substances dissolved in liquids. It uses pressure to reverse the natural osmosis process. The principle of the process is that the medium in which the concentration of a particular substance is to be reduced is separated from the medium in which the concentration is to be increased by a semipermeable membrane. This membrane is subjected to a pressure that must be higher than the pressure created by the osmotic pressure to equalize the concentration. This allows the solvent molecules to migrate against their "natural" osmotic propagation direction. The process pushes them into the compartment where dissolved substances are less concentrated. Typical pressures for reverse osmosis range from 3 to 60 bar. The concentration factor—depending on the amount of remaining water in the concentrate and the initial amount—can be between about 2 and about 100, preferably between about 5 and about 50, and especially between 10 and about 25.

[0025] The osmotic membrane, which only allows the carrier fluid (solvent) to pass through and retains the dissolved substances (solutes), must be able to withstand these high pressures. If the pressure difference more than compensates for the osmotic gradient, the solvent molecules pass through the membrane like a filter, while the "contaminant molecules" are retained. Unlike a conventional membrane filter, osmotic membranes do not have continuous pores. Rather, the ions and molecules migrate through the membrane by diffusing through the membrane material, as described by the solution-diffusion model: The osmotic pressure increases with increasing concentration difference. If the osmotic pressure equals the applied pressure, the process stops. Osmotic equilibrium then exists. A steady outflow of the concentrate can prevent this.At the concentrate outlet, the pressure is either controlled by a pressure regulator or used via a pressure exchanger to build up the pressure required in the system inlet.

[0026] Concentration in step (d) can also be achieved by simple evaporation in a kettle, where the product is heated and the steam is removed. Among the process alternatives mentioned, nanofiltration is preferred. Regardless of the design of this process step, a lactose-containing whey protein concentrate (MPK1) with a dry matter content of approximately 25 to approximately 50 wt.% is obtained in step (d). hydrolysis

[0027] According to the invention, the enzymatic hydrolysis of lactose is carried out using lactase. Alternatively, polymerases or esterases could also be used. However, the lactose would then be transesterified or cross-linked. However, this cross-linking would lead to functional changes in the product. Furthermore, these enzymes are not specific and do not achieve the desired residual lactose content of <0.1% to even <0.01%. The hydrolysis can be carried out both batchwise and continuously within the context of the process according to the invention.

[0028] The hydrolysis is preferably carried out in a stirred tank with continuous inlet and outlet, as well as a dosing device for adding the enzyme and a valve at the bottom of the reactor for discharging deactivated enzyme. It has proven advantageous to use an effective enzyme concentration of approximately 180,000 to 250,000 FCC units of lactase per kg of lactose to be hydrolyzed and to conduct the reaction at temperatures in the range from about 5 to about 50 °C and a slightly acidic pH of about 5 to 6. The incubation time is usually 2 to 12 hours.

[0029] The resulting lactose-free whey protein concentrate (MPK1 or MPK2) then has a lactose concentration of a maximum of 0.1% by weight and in particular less than 0.01% by weight - based on the dry matter. Spray drying

[0030] If dry powders are to be obtained as the final product, subsequent spray drying is the preferred drying process, with the temperature at the inlet typically being about 160 to about 260 °C and at the outlet about 60 to about 120 °C. Alternatively, the products can also be dehydrated by freeze-drying. The residual water content in both processes is a maximum of 10 wt.% and preferably about 2 to about 4 wt.%. Other additives, such as lactoferrin, lecithins, vitamins, or food emulsifiers [EP 1314367 A1, NESTLE] and the like, can be added to the powders before, but preferably after, spraying. INDUSTRIAL APPLICABILITY

[0031] Another object of the invention relates to the use of the lactose-free whey protein powder (MPP) or obtained by the process as described above for human or animal nutrition. EXAMPLES Example 1 Production of a lactose-free whey protein powder

[0032] 1000 L of a pre-concentrated mixed whey with a dry matter content of approximately 10 wt.% was reduced to a volume of 200 L by ultrafiltration at a temperature of 15 °C and a pressure of 2.5 bar, concentrating the desired proteins in the retentate (R1). The resulting permeate (P1), which contained the minerals and a portion of the lactose, was used for other purposes. The dry matter content of the retentate (R1) was approximately 18 wt.%.

[0033] Retentate R1 was subjected to further ultrafiltration, again operated at a temperature of 15 °C but at a pressure of 5 bar. Water from the permeate of a reverse osmosis unit or drinking water was added at a dilution ratio of 100%, thus obtaining a second retentate R) with a dry matter content of approximately 33 wt%; the protein content was approximately 80 wt% based on this dry matter.

[0034] Retentate R2 was then subjected to nanofiltration at approximately 12 °C and a pressure of approximately 30 bar. The resulting third retentate R3 had a dry mass of approximately 36 wt.%.

[0035] Subsequently, the retentate R3 was placed in a hydrolysis tank and incubated with lactase for 7 h at 8 °C while stirring, reducing the residual lactose content to 0.05 wt.% based on the dry mass. The lactose-free whey protein concentrate was then sprayed at an inlet air temperature of 200 °C and an outlet air temperature of 80 °C to form a dry powder with a residual moisture content of 4 wt.%.

[0036] The invention is explained in more detail by an exemplary flow diagram in Figure 1. The following are the meanings: UF = Ultrafiltration NF = Nanofiltration HY = hydrolysis ST = spray drying

Claims

PATENT CLAIMS 1. Lactose-free whey protein concentrates (MPK2), obtained or available according to the following steps: (a) providing a whey source (M); (b) ultrafiltration of the whey (M) from step (a) to obtain a first permeate (P1) and a first retentate (R1); (c) ultrafiltration of the first retentate (R1) from step (b) to obtain a second permeate (P2) and a second retentate (R2); (d) dewatering the second retentate (R2) from step (c) to obtain a lactose-containing whey protein concentrate (MPK1); (e) adding lactase to the second retentate (R2) from step (b or c) or to the lactose-containing whey protein concentrate (MPK1) from step (d) with hydrolysis of the lactose still present to obtain a lactose-free whey protein concentrate (MPK2); and optionally (f) spray-drying the lactose-free whey protein concentrate (MPK2) from step (e).

2. A process for the production of lactose-free whey protein concentrates (MPK2), comprising or consisting of the following steps: (a) providing a whey source (M); (b) ultrafiltration of the whey (M) from step (a) to obtain a first permeate (P1) and a first retentate (R1); (c) ultrafiltration of the first retentate (R1) from step (b) to obtain a second permeate (P2) and a second retentate (R2); (d) dewatering the second retentate (R2) from step (c) to obtain a lactose-containing whey protein concentrate (MPK1); (e) adding lactase to the second retentate (R2) from step (b or c) or to the lactose-containing whey protein concentrate (MPK1) from step (d) with hydrolysis of the lactose still present to obtain a lactose-free whey protein concentrate (MPK2); and optionally (f) spray-drying the lactose-free whey protein concentrate (MPK2) from step (e).

3. Process according to claim 2, characterized in that thin whey or a whey concentrate or a mixture thereof is used as the whey source (M) in step (a).

4. Process according to claims 2 and / or 3, characterized in that in step (a) a whey source (M) is used which has a dry matter in the range of about 4 to about 32 wt.%.

5. Process according to at least one of claims 2 to 4, characterized in that in the first ultrafiltration in step (b) a retentate (R1) is produced which has a dry matter content of about 10 to about 20% by weight.

6. The process according to at least one of claims 2 to 5, characterized in that in the second ultrafiltration in step (c) a retentate (R2) is produced which has a dry matter content of about 20 to about 40% by weight.

7. The process according to at least one of claims 2 to 6, characterized in that the first and second ultrafiltration in steps (b) and (c) are carried out in the temperature range from about 2 to about 25 °C 8. The process according to at least one of claims 2 to 7, characterized in that the first and second ultrafiltration in steps (b) and (c) are carried out in the pressure range from about 0.1 to about 15 bar.

9. The process according to at least one of claims 2 to 8, characterized in that the second ultrafiltration in step (c) is carried out in the presence of drinking water or the permeate of a reverse osmosis system.

10. The process according to claim 9, characterized in that the dilution in the second ultrafiltration in step (c) is about 20 to about 200%, based on the feed.

11. The process according to at least one of claims 2 to 10, characterized in that for further dewatering of the second retentate (R2) in step (d), a further ultrafiltration, nanofiltration, reverse osmosis or evaporation or a combination of the said processes is carried out.

12. The method according to claim 11, characterized in that in step (d) a lactose-containing whey protein concentrate (MPK1) is produced which has a dry matter content of about 20 to about 50% by weight.

13. The process according to at least one of claims 2 to 12, characterized in that in step (e) a lactose-free whey protein concentrate (MPK2) is produced which has a lactose concentration of not more than 0.1% by weight, based on the dry matter.

14. The process according to at least one of claims 2 to 13, characterized in that the lactose-free whey protein concentrate from step (f) is spray-dried to a residual water content of at most 10% by weight.

5. Use of the lactose-free whey protein powder (MPP) according to claim 1 or obtained by the process according to claims 2 to 14 for human or animal nutrition.

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