Process of preparing a fermented dairy product

Abstract

The present invention relates to a process of preparing a fermented dairy product and the fermented dairy product obtained hereby. In particular, the present invention relates to a process of preparing a fermented dairy product where a milk starting material that is used for preparing the fermented dairy product is acidified by using electrodialysis with bipolar membrane, and the acidified liquid milk product is then subjected to ultrafiltration and fermentation. The fermented dairy product obtained has a high protein content, low viscosity and good sensorial properties.

Description

[0001] Process of preparing a fermented dairy product

[0002] Technical field of the invention

[0003] The present invention relates to a process of preparing a fermented dairy product and the fermented dairy product obtained hereby. In particular, the present invention relates to a process of preparing a fermented dairy product where a milk starting material that is used for preparing the fermented dairy product is acidified by using electrodialysis with bipolar membrane, and the acidified liquid milk starting material is then subjected to ultrafiltration and fermentation. The product obtained has a high protein content and low viscosity.

[0004] Background of the invention

[0005] Fermented dairy products are widely known. Further, fermented dairy products such as yoghurt, skyr and fresh cheese that have a high protein content are known in art. However, such known products have, due to the high protein content, a high viscosity and is less creamy and smooth.

[0006] Further, processes to prepare high protein fermented dairy products are known where the processes include ultrafiltration to concentrate the protein content. However, it has been found that such products have a high viscosity and are firm and compact.

[0007] Processes for preparing fermented dairy products that do not include any preacidification are also known. However, such processes require a longer fermentation time and therefore become more acidic.

[0008] Processes of making dairy products using a combination of acidifying a starting milk with an organic acid followed by ultrafiltration (UF) is also known. However, addition of an organic acid results in a dairy product that contains more acid and hence have an acidic off-taste. Further, addition of acids is undesirable since it needs to be labelled on the package of the product and negatively affects the valorisation of the UF permeate obtained as a side stream when concentrating to obtain a high protein content. The presence of citric acid in an UF permeate results in the formation of calcium citrate that is responsible for fouling the membrane. Therefore, the use of organic acids is not desired.

[0009] Hence, an improved process of preparing high protein fermented products without adding any organic acid would be advantageous. In particular, a more efficient process of preparing a high protein fermented dairy product having improved properties would be advantageous.

[0010] Summary of the invention

[0011] Thus, an object of the present invention relates to providing a process of preparing a fermented dairy product that has a high protein content and has improved creaminess, smoothness and mouthfeel. In addition, it is an object of the present invention to provide a fermented dairy product that has not been added any chemical acidifying agents, such as organic acids.

[0012] In particular, it is an object of the present invention to provide a process for preparing a fermented dairy product that solves the above-mentioned problems of the prior art with regard to acidity.

[0013] Thus, one aspect of the invention relates to a process of preparing a fermented dairy product comprising the following process steps:

[0014] i) providing a milk starting material;

[0015] ii) adjusting pH of the milk starting material to be in the range of 5.8 to 6.5 by subjecting the milk starting material to electrodialysis using one or more bipolar membrane(s);

[0016] iii) ultrafiltration (UF) of the pH adjusted milk starting material to obtain a UF retentate and a UF permeate;

[0017] iv) fermenting the UF retentate obtained in step iii) to obtain a fermented dairy product.

[0018] Another aspect of the present invention relates to a fermented dairy product comprising:

[0019] - a protein content of at least 5% by weight - a calcium content of maximum 30 mg per gram protein

[0020] - a potassium content of maximum 15 mg per gram protein

[0021] wherein the viscosity of the fermented dairy product is 45,000 mPa*s or below.

[0022] Brief description of the figures

[0023] Figure 1 shows a schematic overview of an example of the system of electrodialysis with bipolar membrane (EDBM). The EDBM in figure 1 comprises CEM and BM. BM refers to bipolar membrane and CEM refers to cationic exchange membrane.

[0024] Figure 2 shows a schematic overview of another example of the system of electrodialysis with bipolar membrane (EDBM). The EDBM in figure 2 comprises AEM, CEM and BM. BM refers to bipolar membrane, AEM refers to anionic exchange membrane and CEM refers to cationic exchange membrane.

[0025] Figure 3 shows a flow diagram of the process of preparing a fermented dairy product using electrodialysis with bipolar membrane according to the invention.

[0026] Figure 4 shows a flow diagram of a process of preparing a fermented dairy product using pH adjustment by adding citric acid.

[0027] Figure 5 shows a flow diagram of the process of preparing a fermented dairy product using electrodialysis with bipolar membrane according to the invention including an ultrafiltration step before acidification.

[0028] The present invention will now be described in more detail in the following.

[0029] Detailed description of the invention

[0030] Definitions:

[0031] Prior to discussing the present invention in further details, the following terms and conventions will first be defined: All references to singular characteristics or limitations of the present invention shall include the corresponding plural characteristics or limitations, and vice versa, unless otherwise specified or clearly implied to the contrary by the context in which the reference is made.

[0032] All percentages referred to herein are percentages by weight unless otherwise stated. The term "w / w" also refers to weight percentages. For example, 1% w / w refers to a composition comprising 1% by weight of a compound.

[0033] Fermented dairy product:

[0034] The process of the present invention relates to the preparation of a fermented dairy product. The fermented dairy product may be any type of fermented dairy product, and the invention should not be limited to the preparation of any specific dairy product. For example, the fermented dairy product obtained by the process of the present invention may be selected from the group consisting of skyr, fresh cheese, soft cheese, yoghurt, kefir, cultured buttermilk, cultured cream, sour milk and sour cream.

[0035] Preferably, the fermented dairy product is selected from the group consisting of skyr, fresh cheese, soft cheese and yoghurt.

[0036] The term "fresh cheese" refers to a cheese that is made without pressing cheese curd to squeeze out the whey, or milk liquids, resulting in a cheese with a high moisture content. Further, a fresh cheese is not aged. The fresh cheese may include a cream cheese, and a fresh cheese is spreadable.

[0037] Examples of fresh cheeses are cream cheese, cottage cheese, quark and ricotta.

[0038] Soft cheeses are also made with a high moisture content, but besides from being spreadable, soft cheeses are also sliceable. The fresh cheese is not sliceable. Feta is an example of a soft cheese.

[0039] Milk starting material:

[0040] In the method of preparing the fermented dairy product according to the present invention, the fermented dairy product is prepared from a milk starting material. The term "milk" in "milk starting material" refers to that the milk starting material is in liquid form. Hence, the milk starting material is liquid.

[0041] The type of milk used as starting material is not to be seen as a limitation of the present invention, and in principle, any milk product may be used as the milk starting material.

[0042] However, the milk starting material may be for example be selected from the group consisting of whole milk (full-fat milk), low-fat milk, reduced fat milk, fat-free milk (skim milk), buttermilk, reconstituted milk powder, lactose reduced milk, low-lactose milk, lactose-free milk, heat treated milk (e.g. pasteurised or UHT treated milk), raw unfiltered milk, homogenised milk, mineral reduced milk, whey protein reduced milk, micellar casein isolate, micellar casein concentrate, an ultrafiltration permeate of milk and combinations thereof.

[0043] Preferably, the milk starting material is selected from the group consisting of whole milk (full-fat milk), low-fat milk, reduced fat milk, fat-free milk (skim milk), buttermilk, reconstituted milk powder, lactose reduced milk, low-lactose milk, lactose-free milk, heat treated milk (e.g. pasteurised or UHT treated milk), raw unfiltered milk, homogenised milk, mineral reduced milk, whey protein reduced milk, an ultrafiltration permeate of milk and combinations thereof.

[0044] More preferably, the milk starting material is selected from the group consisting of whole milk, low-fat milk, reduced-fat milk, fat-free milk, lactose reduced milk, low-lactose milk, lactose-free milk, an ultrafiltration permeate of milk, and combinations thereof.

[0045] In a preferred embodiment of the invention, the milk starting material is an ultrafiltration permeate of milk, where the milk is any of whole milk, low-fat milk, reduced-fat milk, fat-free milk, lactose reduced milk, low-lactose milk, lactose-free milk, preferably low-fat milk, reduced-fat milk, fat-free milk. After ultrafiltration of milk, a permeate and a retentate is obtained. The ultrafiltration permeate is acidified using the electrodialysis with bipolar membrane and the acidified ultrafiltration permeate is mixed with the ultrafiltration retentate before further processing, see figure 5. Furthermore, the milk starting material provided and used in the process of the present invention for preparing a fermented dairy product may be based on milk from mammals, such as cows, buffalos, goats, sheep, camel, yaks, or mixtures thereof. In a preferred embodiment of the present invention, the milk starting material is from cows, such as bovine milk. The term bovine milk and cow's milk refer to the same and may be used interchangeable.

[0046] In a preferred embodiment of the invention, the milk starting material is pasteurised milk, and especially pasteurised bovine milk. When referring to pasteurised milk, it may in principle be any type of the above-mentioned milk starting materials that have been pasteurised, such as for example pasteurised whole milk, low-fat milk, reduced fat milk, fat-free milk, raw unfiltered milk, mineral reduced milk, lactose reduced milk, low-lactose milk, lactose-free milk and ultrafiltration permeate of milk.

[0047] The fat content of the milk starting material is not critical for the present invention, and therefore a milk starting material could have either low or high fat content depending on the product prepared. Hence, the fat content of the milk starting material may be up to 5% by weight, such as up to 3% by weight.

[0048] However, in an embodiment of the present invention, the milk starting is material is low in fat and comprises fat in an amount of 0.1% by weight or less. Preferably, the milk starting material comprises fat in an amount of 0.05% by weight or less. This will result in a low fat fermented dairy product.

[0049] The fat in the milk starting material may be removed by a process known as fat standardization. Traditionally, standardization of milk has been achieved by removing nearly all the fat (cream) from the starting milk (by separation technique) and adding back a known amount of cream thereto to achieve a predetermined protein / fat ratio in the milk. Fat standardization is typically performed by subjecting the milk to centrifugation which separates the cream fraction from the skim milk fraction (reduced fat milk fraction). In another embodiment of the invention, the milk starting material has not been subjected to any fat standardisation and the fat content is similar to the fat content typically found in milk, i.e. about 3,5% by weight.

[0050] The milk starting material preferably comprises both casein and milk serum protein (whey protein) and preferably the ratio between whey protein and casein in the milk starting material is about the same ratio as found in natural milk, but in principle the whey protein and casein content may be different from the content present in natural milk. However, in the embodiment of the invention where a milk ultrafiltration permeate is used as the milk starting material, the milk starting material does not comprise casein or milk serum protein. The proteins are present in the ultrafiltration retentate and after acidification of the ultrafiltration permeate using EDBM, the acidified ultrafiltration permeate is mixed with the ultrafiltration retentate comprising the proteins to make acidified milk

[0051] The casein in the milk starting material is primarily present in the form of casein micelles, similar or even identical to the casein micelles found in e.g. skimmed milk.

[0052] The term "milk serum" refers to the liquid phase of milk in which whey proteins and fat globules are dispersed.

[0053] In the context of the present invention, the terms "milk serum protein" and "serum protein" refer to the protein found in the milk serum. The milk serum protein may also be referred to as whey protein. The milk serum protein typically includes beta-lactoglobulin, alpha-lactalbumin, bovine serum albumin, immunoglobulin and osteopontin as well as lactoferrin and lactoperoxidase.

[0054] The term "protein" refers in the context of the present invention to polypeptides containing at least 10 amino acids and encompasses both single polypeptides and aggregates of polypeptides.

[0055] The term "non-protein nitrogen" (NPN) refers to nitrogen found in molecules that are not protein. In milk, a significant portion of the NPN comes from urea, ammonium, salts and small peptides containing less than 10 amino acids. In an embodiment of the invention, the ratio between milk serum protein and casein in the milk starting material is in the range of 10:90 to 30:70, preferably 15:85 to 25:75, more preferably about 20:80. For example, the milk starting material used for EDBM can have a reduced whey protein content as compared to milk.

[0056] In the obtained fermented dairy product, the whey protein provides moisture by effectively binding water, On the other hand, casein is primarily responsible for the texture achieved, as casein has the ability to cu rd le / coag ulate during fermentation. Hence, the milk starting material should preferably comprise whey protein and casein in about the same ratio as found in milk.

[0057] Therefore, the casein content in the milk starting material should be in the range of 70-90% by weight of the total protein content, preferably about 75-85% and more preferably about 80% by weight of the total protein content. The amount of casein of the total protein content should not exceed 90% by weight, because this will result in a fermented dairy product that is perceived as grainy.

[0058] In some embodiments of the invention, the milk serum protein of the milk starting material is present in undenatured, native form, i.e. the same form as in raw milk, which has not been subjected to a denaturing heat treatment. It is therefore also preferred that the milk starting material has not been subjected to conditions that have resulted in significant protein denaturation, such as e.g. high temperature for prolonged durations. However, the milk starting material may be pasteurised. Pasteurisation of the milk starting material may take place under standard conditions, namely, heat treatment of the milk starting material at a temperature and time sufficient to kill pathogens, typically at 72°C for 15 seconds.

[0059] In an embodiment of the invention, the milk starting material comprises a total amount of protein in the range of 1-10% (w / w). Preferably, the milk starting material comprises a total amount of protein in the range of 2-8% (w / w), and, even more preferably, the milk starting material comprises a total amount of protein in the range of 3-5% (w / w), such as 3.0-4.6. The solid content of the milk starting material may vary depending on the used feed, but it is typically in the range of 1-30% (w / w). Preferably, the solid content of the milk starting material is in the range of 4-25% (w / w). Even more preferably, the solid content of the milk starting material is in the range of 5-15% (w / w).

[0060] The pH of the milk starting material is the same as in natural milk, i.e. typically in the range of 6.8-7.0.

[0061] In an embodiment of the present invention, the milk starting material is an organic milk from an organic milk source. In a preferred embodiment of the invention, the milk starting material is an organic skimmed milk.

[0062] In the context of the present invention, the term "organic milk" refers to milk produced by mammals, such as cattle, raised according to the following: the cattle must have free access to certified organic pasture for the entire grazing season. This period is specific to the farm's geographical climate but must be at least 120 days per year and preferably at least 150 days. Due to the weather, season, or climate, the grazing season may or may not be continuous. Organic cattle diets must contain at least 30 percent dry matter (on average) from certified organic pasture. Dry matter intake (DMI) is the amount of feed an animal consumes per day on moisture-free basis. The rest of its diet must also be certified organic, including hay, grain, and other agricultural products. The livestock should be managed without antibiotics, added growth hormones, mammalian or avian byproducts, or other prohibited feed ingredients (e.g. urea or arsenic compounds).

[0063] pH adjustment:

[0064] In the process of the present invention, the milk starting material is pH adjusted to a pH in the range of 5.8 to 6.5 by subjecting the milk starting material to electrodialysis using one or more bipolar membrane(s).

[0065] The pH is preferably adjusted to pH 5.9 to 6.4, more preferably 6.0 to 6.3 and even more preferably 6.0 to 6.2. pH should not be adjusted to a pH below 5.8, because at such low pH precipitations will be formed in the milk starting material and coagulation and aggregation of protein will begin. This is wished avoided because precipitation, aggregation and coagulation will make it impossible to prepare the following ultrafiltration step as the membrane will be clogged. Further, if the pH adjustment is to a pH below 5.8, the heat treatment of the pH adjusted milk after ultrafiltration will cause the milk to coagulate and protein aggregate. Hence, the fermentation process will be impaired and therefore also the product properties and taste of the obtained fermented product.

[0066] Preferably, chemical acidifying agents or acid producing microorganisms have not been added to the milk starting material before the ultrafiltration step of the present invention. Hence, the pH adjustment before ultrafiltration is only obtained by subjecting the milk starting material to electrodialysis with bipolar membrane. Hence, in an embodiment of the present invention, the method excludes addition of chemical acidifying agents and / or acid producing microorganisms to the milk starting material before ultrafiltration.

[0067] The term "chemical acidifying agents" refers to compounds, such as acids and acidifying agents, being in liquid, solid or gas form and comprising ions of hydrogen (H+). The chemical acidifying agents are typically organic acids or inorganic acids. Hence, the chemical acidifying agents do not cover acidification by using electrodialysis with a bipolar membrane. The chemical acidifying agents are food grade acids, such as citric acid, lactic acid, acetic acid, hydrochloric acid, malic acid and glucono-delta-lactone.

[0068] Hence, in an embodiment of the present invention no chemical acidifying agents or acid producing microorganisms have been added to the milk starting material for pH adjustment before the ultrafiltration or the fermentation step. In particular, in an embodiment citric acid, lactic acid, acetic acid, hydrochloric acid, malic acid and glucono-delta-lactone have not been added to the milk starting material or during the method of preparing a fermented dairy product.

[0069] In the process according to the present invention calcium is removed from a milk starting material by adjusting the pH of the milk starting material by electrodialysis with a bipolar membrane. Chemical acidifying agents or acid producing microorganisms are preferably not added to the milk starting material. It has been found by the inventors of the present invention that it is possible to prepare fermented products with a high protein content and with efficient and controlled removal of calcium without addition of any chemical acidifying agents until the fermentation step.

[0070] In prior art, the process of preparing fermented dairy products may comprise a pre-acidification step by adding an organic acid to for example skim milk. Said pre-acidification may for example be by adding citric acid. However, addition of organic acid is undesirable as it needs to be labelled on the package, and it negatively affects the process of valorisation of the UF permeate. The presence of for example citric acid in the UF permeate results in the formation of calcium citrate that is responsible for fouling of the membrane.

[0071] In the method of the present invention, the inventors have surprisingly found that a controlled removal of calcium from the milk starting material can be obtained by pH adjusting the milk starting material by using electrodialysis with a bipolar membrane and subsequently ultrafiltering the milk starting material that has been pH adjusted (by EDBM).

[0072] By decreasing pH of the milk starting material by using the electrodialysis with bipolar membrane, calcium bound in casein micelles disassociate into free calcium. The free calcium can be separated out in the ultrafiltration step. This will affect the amount of total calcium content in the milk starting material.

[0073] Further, one advantage of using EDBM is that calcium partially is removed directly by the electrodialysis process. Since some of the free calcium is passing the CEM into water / salt solution. Hence, the EDBM process itself will remove some calcium. Further, the use of EDBM for acidification will remove monovalent ions such as potassium from the milk starting material. This leads to changes in ionic strength and mineral balance in both serum phase and micellar colloidal phase. By pH adjustment with electrodialysis with bipolar membrane, no acidifying agents are used. Hence, besides from the process of the present invention provides a controlled removal of calcium, the process also provides an ultrafiltration permeate without any chemical acidifying agents and a fermented dairy product without any chemical acidifying agents.

[0074] Hence, in a preferred embodiment the process according to the present invention does not comprise addition of a chemical pH adjusting agent, i.e. no organic acid is added.

[0075] In addition, it has surprisingly been found by the inventors of the present invention that a fermented dairy product obtained by reducing the calcium content in the milk starting material by a pre-acidifying step using electrodialysis with bipolar membrane in combination with ultrafiltration as compared to a preacidifying step using an organic acid in combination with ultrafiltration have improved functional and sensorial properties. For example, it has surprisingly been found that a fermented dairy product obtained from a milk starting material, such as skim milk, that has been acidifying by using electrodialysis with bipolar membrane has a lower viscosity and a lower gel strength than a fermented dairy product obtained after pre-acidification with citric acid. Gel strength and viscosity is connected and are both parameters of a product relating to the firmness.

[0076] Furthermore, gel strength and viscosity are connected to smoothness and creaminess of a fermented product. The lower the viscosity, the more creamy and smooth a fermented product is.

[0077] Further, it has surprisingly been found that the fermented dairy product obtained from pre-acidification with electrodialysis with bipolar membrane followed by concentration and calcium removal using ultrafiltration has a lower syneresis and more mild taste than a fermented dairy product obtained after pre-acidification with citric acid.

[0078] In an embodiment of the invention, the temperature of the milk starting material is, or is adjusted to be, in the range of 2° to 15°C, preferably 4°C to 10°C. At temperatures in this range, the calcium removal and mineral balance change during ultrafiltration is better. At temperatures in the range of 2°C to 15°C, beta- casein micelles are dissolved, and the casein micelles are disturbed such that calcium may leach out.

[0079] Electrodialysis with bipolar membrane:

[0080] In an aspect of the process of the present invention, the milk starting material is subjected to electrodialysis with a bipolar membrane (EDBM) to adjust the pH of the milk starting material to be in the range of 5.8 to 6.5.

[0081] It has surprisingly been found by the inventors of the present invention that not only acidification of a milk starting material can be obtained by using EDBM, but a fermented dairy product obtained from the milk starting material that has been acidified by using EDBM has improved functional and sensorial properties.

[0082] EDBM is an electro-membrane process that could be used to split water into hydrogen and hydroxide ions which can subsequently be used to change the pH of a milk starting material (see figure 1).

[0083] Therefore, EDBM allows to change the pH of a milk starting material without adding any chemical agents such as citric acid, lactic acid, acetic acid and hydrochloric acid. The use of EDBM for acidification allows the solubilisation of calcium from micellar caseins that are subsequently removed during ultrafiltration.

[0084] Figure 1 shows the configuration of the EDBM. In the configuration of the EDBM shown in figure 1, a cationic exchange membrane (CEM) is placed close to the anode and next to the cathode is also placed a cation exchange membrane (CEM). In between the CEMs is placed a bipolar membrane (BM). In figure 1, the EDBM is made with 50 cell pairs with 51 CEMs and 50 BMs, but this may vary depending on the scale of the production. The EDBM may also be made with one or more anionic exchange membrane (AEM), one or more CEM, and one or more BM.

[0085] The EDBM may comprise up to 500 pairs. One pair comprises a bipolar membrane, a compartment with a stream for water and a compartment with a stream for the milk starting material. The term "stack" refers to all cell pairs placed between an anode and cathode. In figure 1 is one stack with 50 cell pairs shown.

[0086] The stack may be placed in parallel or in series. Further, the pH adjustment in several stacks may be continuously or in a batch. The speed of decrease in the pH in the EDBM is a question of how many stacks are used. The more stacks used, the larger is the membrane surface area, and hence the faster is the acidification process.

[0087] When the electric potential (voltage) is applied to the system, the water molecules present at the interface of cationic and anionic layers of the bipolar membranes are split into hydrogen (H+) and hydroxide ions (OH-). The hydrogen and hydroxide ions are transported towards the cathode and anode respectively. In an embodiment of the invention, the EDBM stack is made with CEMs and BMs.

[0088] However, AEMs can also be used. The use of AEM between anode and electrolyte solution will avoid the migration of anions toward the concentrate.

[0089] Figure 2 shows a configuration of the EDBM including AEM. Figure 2 shows a CEM is placed close to the cathode and an AEM is placed close to the anode. In between the AEM and CEMs are placed bipolar membranes (BM).

[0090] The milk starting material may be circulated to the EDBM stack in between the BM and the CEM, while water or salt solution is circulated to the EDBM in the other compartments (between AEM and BM or between CEM and BM).

[0091] The hydrogen ion (H+) is transported to the milk starting material which decrease its pH, while the negative charged ions (OH-) is transported to the water or salt solution, which increase its pH. Further, calcium and other minerals are transported through the CEM to other compartment containing water or salt solution. Hereby the milk starting material will after EDBM treatment have a decreased pH and a lower calcium content.

[0092] The inventors of the present invention have found out the EDBM can be used to pH adjust a milk starting material resulting in solubilisation of bound calcium (micellar or colloidal calcium) and that this solubilised calcium can be removed by an ultrafiltration step. In addition, it was found by the inventors of the present invention that a fermented dairy product obtained by acidifying with EDBM and removal of calcium with ultrafiltration had improved functional and sensorial properties as compared to a fermented dairy product obtained from acidifying with an organic acid followed by ultrafiltration.

[0093] Figure 3 shows a schematic overview of the process on the present invention using EDBM for acidification followed by ultrafiltration and further processing / fermentation of the ultrafiltration retentate to obtain a final fermented dairy product.

[0094] Figure 4, on the contrary, shows a schematic overview of a process using addition of citric acid for acidification instead of EDBM.

[0095] In an embodiment of the invention, the electrodialysis with bipolar membrane further comprises one or more cationic exchange membrane(s), one or more anionic exchange membrane(s) and one or more bipolar membrane(s).

[0096] In an embodiment of the process of the present invention, the electrodialysis with bipolar membrane is carried out at a temperature in the range of 2°C to 40°C, preferably at a temperature in the range of 2°C to 40°C, more preferably in the range of 5°C to 35°C and most preferably at a temperature in the range of 5°C to 25°C.

[0097] The temperature during electrodialysis is dependent on the membrane used and therefore, the present invention should not be limited to the temperature used during EDBM. Some membranes can be used at lower temperatures and some at higher temperatures. In one embodiment of the invention, the temperature during electrodialysis is from 25°C to 40°C, such as from 30°C to 35°C. Without being bound by any theory, the inventors of the present invention believe that the ion transport of EDBM is better at higher temperatures, i.e. at temperatures from 25°C to 40°C.

[0098] Addition of ultrafiltration retentate:

[0099] In an embodiment of the present invention, where the milk starting material is a milk ultrafiltration permeate, the acidified milk ultrafiltration permeate is mixed with an ultrafiltration retentate before further processing. The ultrafiltration retentate comprises proteins and by mixing with the acidified milk ultrafiltration permeate, the pH of the mixture decreases and hence calcium bound in casein micelles disassociate into free calcium which can be removed in the following ultrafiltration step.

[0100] Ultrafiltration:

[0101] The milk starting material that has been pH adjusted by electrodialysis with a bipolar membrane is subjected to ultrafiltration (UF) with an ultrafiltration membrane to provide a UF permeate and a UF retentate.

[0102] In the present invention, the milk starting material has been subjected to electrodialysis with a bipolar membrane to decrease pH and hence disassociate calcium. The lower the pH, the more calcium is removed in the ultrafiltration step. The combination of decreasing pH by using electrodialysis with bipolar membrane followed by ultrafiltration makes it possible to control the reduction of calcium. Therefore, the addition of organic acids can be avoided.

[0103] The ultrafiltration (UF) membrane allows passage of small peptides, minerals and some lactose into the permeate while retaining the milk serum protein, micellar casein, dissolved beta-casein and some lactose. Approximately, 50% of the lactose in the milk starting material will be retained in the retentate while approximately 50% penetrates the UF membrane and is present in the permeate. In fresh milk, the lactose content is about 4.4 to 4.5% by weight. After the ultrafiltration step in the process of the present invention, the lactose content in the UF retentate is about 4.0, but with a much higher protein content.

[0104] According to an embodiment of the present invention, the cut-off of the ultrafiltration membrane is in the range of 2000 Da to 50000 Da, preferably 2500 to 30000 Da, more preferably about 20000 Da. In a preferred embodiment of the invention, a polymeric membrane is used having a molecular weight cut-off of 20000 Da. In the embodiment of the invention where the milk starting material is an ultrafiltration permeate of milk, the ultrafiltration before and after acidification may be by using the same ultrafiltration membrane.

[0105] The ratio between the casein and milk serum protein will be the same as for the milk starting material used.

[0106] The concentration factor of the ultrafiltration step may for example be in the range of 1.1 to 7.5. Preferably, the concentration factor is in the range of 2.0 to 6.5 and more preferably 2.5 to 6.0. Most preferably, the concentration factor is 2.8 to 5.1.

[0107] A concentration factor in the range of 2.8 to 5.1 corresponds to obtaining a protein content in the ultrafiltration retentate in the range of 9.8% to 18% by weight.

[0108] The calcium content in the UF retentate of the present invention is reduced as compared to the calcium content in the milk starting material, since some calcium will be present in the UF permeate. The amount of calcium removed from the milk starting material in the ultrafiltration step is dependent on the concentration factor and the pH. Further, the amount of calcium removed can be adjusted by adjusting the pH of EDBM and the concentration factor in the ultrafiltration step. In addition, the protein content in the UF retentate is increased. Hence, the content of calcium of the total protein content is decreased in the UF retentate (gram calcium per gram total protein).

[0109] For example, the calcium content in the fermented dairy product is maximum 30 mg per gram total protein, preferably, maximum 29 mg calcium per gram protein.

[0110] In the UF retentate according to the present invention (i.e. the UF retentate obtained after subjecting milk starting material to electrodialysis with a bipolar membrane and then perform ultrafiltration) has a calcium content of the protein content being 30 mg calcium per gram protein or less, preferably 28 mg calcium per gram protein or less, and most preferably 26 mg calcium per gram protein or less. As mentioned earlier, it is important for the present invention that a substantial amount of calcium is removed, and this is only obtained by the combined effect of decreasing pH (by using electrodialysis with bipolar membrane) followed by ultrafiltration. However, it is also important that not all calcium is removed, since the removal of too much calcium will result in coagulation of casein.

[0111] If for example skim milk is used as the milk starting material, the calcium content is typically about 1200-1400 mg / kg and the protein content is about 35 g / kg. This corresponds to a calcium content of 1.2 to 1.4g per 35g protein (in 1 kg milk) which is equal to 34-40 mg calcium per gram protein.

[0112] After subjecting a milk starting material to electrodialysis with bipolar membrane and ultrafiltration to a 10% protein content, the calcium content in the UF retentate is typically less than 30 mg calcium per gram protein.

[0113] The lower the pH is after electrodialysis, the more calcium is removed.

[0114] Calcium is measured using the standard method ICP— OES (DS / EN ISO 11885m:2009)

[0115] In an embodiment of the invention, the process comprises diafiltration after the ultrafiltration step, i.e. diafiltration of the UF retentate to further reduce the calcium content. The membrane used for the diafiltration is also an ultrafiltration membrane. In an embodiment, the membrane used for ultrafiltration and diafiltration is the same membrane.

[0116] The concentration factor of the diafiltration step is in an embodiment of the invention also in the range of 1.1 to 7.5.

[0117] The concentration factor is defined as the weight ratio between the protein content in the liquid milk starting material to the protein content in the retentate obtained. Hence, if the concentration factor (CF) is 3, the protein content in the UF retentate has been concentrated 3 times as compared to the protein content in the milk starting material. Hence, if the milk starting material has a protein content of 3.5% by weight and a CF of 3, the protein content in the UF retentate is (3.5x3) 10.5% by weight.

[0118] The UF retentate and the DF retentate obtained may in an embodiment of the invention be diluted with a liquid to obtain a diluted UF retentate or diluted DF retentate having a protein content of 5-18% by weight. The protein content is measured using the Kjeldahl method (ISO 8968-l:2014 / IDF 20-1).

[0119] Useful, but not limiting, examples of diluents which can be used for diluting of the UF retentate or the DF retentate are demineralized water or reverse osmosis(RO) water. Demineralized water may also be referred to as distilled water.

[0120] The RO water refers in the context of the present invention to any permeate from membrane filtration of milk and tap water that has been subjected to reverse osmosis. Hence, RO water may be a permeate obtained by reverse osmosis of a permeate from ultrafiltration of milk, reverse osmosis of a permeate form nanofiltration of milk, or reverse osmosis of tap water.

[0121] In a preferred embodiment of the invention, the UF retentate is diluted with RO water to obtain a content of total protein of 5% to 18% by weight.

[0122] In an embodiment of the invention, the temperature during the ultrafiltration (and diafiltration) step is in the range of 2°C to 15°C, preferably 4°C to 10°C.

[0123] Heat treatment:

[0124] In one embodiment, the process of the present invention comprises heat treatment of the UF retentate before fermenting into a fermented dairy product. The heat treatment is typically at a temperature in the range of 75°C to 95°C for 2 to 10 minutes. Preferably, at 80°C to 90°c for about 5 minutes, and more preferably 80°C to 85°C. The lower the pasteurization temperature is of the UF retentate, the lower is the gel strength of the fermented product.

[0125] Fermentation:

[0126] In the process of the present invention, the UF retentate obtained from acidifying a milk starting material by using EDBM and ultrafiltration is subjected to fermentation to obtain a fermented dairy product. The fermentation step may be any fermentation process known in the art and the present invention should not be limited to any specific fermentation process.

[0127] However, in some embodiments of the invention fermentation is carried out by the addition of lactic acid producing bacteria or kefir grains to the UF retentate. In the context of the present invention, the lactic acid producing bacteria may also be referred to as a lactic acid culture.

[0128] Different lactic acid cultures may be used depending on the type of fermented product to obtain. For example, the two most common lactic acid cultures known to produce yoghurt is Streptococcus thermophilus and Lactobacillus bulgaricus. Other types of dairy fermented products are having different taste, for example sour milk and buttermilk. For these types of products some Nordic cultures are used for the fermentation, such as Lactococcus cremoris, Lactococcus lactis, Lactococcus diacetylactis and Leuconostoc.

[0129] Depending on which cultures are used, different aroma compounds are produced in different amounts. In other words, the flavor of the fermented milk product is dependent of the cultures used. In addition, the temperature and time during the fermentation is relevant for the taste obtained.

[0130] During the fermentation process, the bacteria "consume" the sugar in the milk starting material, and the cultures causes the proteins in the milk to curdle, which creates a thick, creamy texture.

[0131] Greek yoghurt is made similarly to yoghurt but is strained after the fermentation to remove whey.

[0132] Skyr is a traditional fermented dairy product of Iceland, and it is gaining popularity around the world. The preparation of skyr includes that whey is slowly drained leaving a thick, sour product with a high protein content and low sugar content.

[0133] Kefir is a drinkable fermented dairy product made by fermenting with kefir "grains" Fermented dairy product:

[0134] An aspect of the present invention relates to a fermented dairy product comprising:

[0135] - a protein content of at least 5% by weight

[0136] - a calcium content of maximum 30 mg per gram protein

[0137] - a potassium content of maximum 15 mg per gram protein.

[0138] wherein the viscosity of the fermented dairy product is 45,000 mPa*s or below.

[0139] The fermented dairy product is obtained by the process according to the present invention. Hence, the fermented dairy product is obtained by pH adjusting a milk starting material by using EDBM and not by adding a chemical acidifying agent. This results in a fermented dairy product that has a lower viscosity and a lower gel strength than a fermented dairy product obtained by pH adjusting by addition of an acid. When the viscosity is lower, the fermented dairy product will also be perceived as less firm, as having increased smoothness and increased creaminess.

[0140] In an embodiment of the invention, the viscosity of the fermented dairy product is maximum 42,000 mPa*s, such as maximum 40,000 mPa*s, and more preferably maximum 35,000 mPa*s.

[0141] The fermented dairy product of the present invention is characterized by having a lower viscosity than a fermented dairy product obtained by pre-acidifying with addition of an acid.

[0142] Preferably, the protein content is at least 8% by weight, such as at least 9% by weight, most preferably at least 10% by weight.

[0143] Further, the calcium content in the fermented dairy product is maximum 29 mg per gram protein, more preferably maximum 28.5 mg calcium per gram protein.

[0144] The potassium content is maximum 15 mg per gram protein, such as maximum 14.5 mg potassium per gram protein. The fermented dairy product according to the present invention does not comprise any added chemical acidifying agent. Hence, the fermented dairy product does not comprise any added organic acid or inorganic acid.

[0145] In a further embodiment of the invention, the fermented dairy product has a gel strength of 800 gram or less. The gel strength is preferably 700 gram- or less, more preferably 500 gram or less. As earlier disclosed, gel strength is connected to the viscosity, smoothness and creaminess of a fermented dairy product. For example, the lower the gel strength, the lower viscosity and then an increased creaminess and smoothness. Both gel strength and viscosity are qualitative methods for analyzing how a product is perceived.

[0146] In also an embodiment of the present invention, the fermented dairy product has a citric acid content of 0.22% by weight (g / lOOg) or less, such as of 0.20% by weight or less, preferably 0.18% by weight.

[0147] In a further embodiment of the present invention, the fermented dairy product has an ash content of 1.05% by weight (g / lOOg) or less, such as 1.0% by weight or less.

[0148] In also an embodiment of the invention, the fermented dairy product has a sodium content of at least 0.40% by weight (g / lOOg).

[0149] In also an embodiment of the present invention, the solid content of the fermented dairy product is in the range of 10% to 20% by weight, such as in the range of 12% to 18% by weight, more preferably in the range of 13-16% by weight. Therefore, the moisture content in the fermented dairy product is typically in the range of 80% to 90% by weight, such as 82% to 88% by weight, preferably 84% to 87% by weight.

[0150] It should be noted that embodiments and features described in the context of one of the aspects of the present invention also apply to the other aspects of the invention. The invention will now be described in further details in the following non-limiting examples.

[0151] Examples

[0152] Example 1: Comparing process of the invention with acidification with organic acid and no pH adjustment

[0153] An example was made where the process of the invention using acidification with EDBM followed by ultrafiltration and processing into a fermented product was compared to using an organic acid for acidification and using no acidification.

[0154] Pasteurised skim milk was acidified using either citric acid (CA) or the electrodialysis with bipolar membrane (EDBM) process.

[0155] The effect of pre-acidification of milk to pH 6.0 and 6.4 was analysed and compared to no acidification (pH 6.8) of the milk. The acidification to pH 6.0 and 6.4 was made with either EDBM or by addition of citric acid.

[0156] Further, the effect of different temperatures during pasteurisation of the obtained acidified and ultrafiltered samples were analysed, using pasteurisation to either 80°C, 85°C or 90°C.

[0157] 12 different samples were prepared as disclosed in table 1 below. ED refers to acidification with electrodialysis with a bipolar membrane while CA refers to acidification with citric acid. N / A refers to "not applied", i.e. no pre-acidification of skim milk is performed.

[0158] Table 1:

[0159] Sample No. Initial pH before Acidification Pasteurisation fermentation method temperature (°C) 1 6.0 ED 90 2 6.0 ED 85 3 6.0 CA 90 4 6.0 CA 80

[0160]

[0161] 5 6.8 N / A 80

[0162] 6 6.8 N / A 85 7 6.8 N / A 90 8 6.8 N / A 80 9 6.4 ED 80 10 6.4 ED 90 11 6.4 CA 85 12 6.4 CA 85

[0163]

[0164] A pilot scale electrodialysis unit with a module (EDR-Y / 2x50-0.8) containing 50 membrane cell pairs from MembBrain (Straz pod Ralskem. Czech Republic) was used. The effective surface area of one membrane was 400 cm2. The electrodialysis module consisted of heterogenous cation-exchange membranes (CEM. RALEX®. CMH-PES) and bipolar membranes (BP. RALEX®) as shown in figure 1. The electrodialysis unit was equipped with sensors for online measurement of conductivity, pH, temperature, electrical current and voltage.

[0165] Figure 1 shows a configuration of ED stack used in the process. CEM represents cation exchange membranes and BM represents bipolar membranes.

[0166] The EDBM process was carried out with 250 kg of skim milk as diluate and 250 kg of NaCI (1%. w / v) solution as concentrate at a constant DC voltage of 75V. The NaCI solution is corresponding to "water" mentioned in figure 1.

[0167] For acidification using citric acid, a 20% concentration from S.A. Citrique Beige N.V. was used.

[0168] The samples of acidified milk (250 Kg) were ultrafiltered (molecular weight cut off membrane: 10 000 Da) to reach a protein content of approximately 10% (w / w) in the ultrafiltration (UF) retentate. The samples of concentrated skim were then heat treated to either 80°C, 85°C or 90°C for 5 min according to table 1 and fermented using Mild 2.0 lactic acid culture (Chr. Hansen A / S. Denmark). The 12 samples were fermented in small 250ml_ cups as a set yogurt. Analysis:

[0169] The 12 samples were analysed for the content of protein, fat, lactose, dry matter and minerals (calcium, Phosphorous, Potassium, Sodium, Magnesium and Chloride) using Foss MilkoScan™ FT3 or at Eurofins Steins Laboratory (Vejen. Denmark). The method used is as listed in table 2 below, unless otherwise stated.

[0170] Table 2: Methods used for the quantification of different chemical components in the milk samples.

[0171] Protein (N*6.38) Kjeldahl (ISO 8968-l:2014 / IDF 20-1)

[0172] Total solids Gravimetric (ISO 6731:2010 / IDF 21)

[0173] Ash Gravimetric (NMKL 173:2005)

[0174] Chloride (Cl) Titrimetric (NMKL 178:2004)

[0175] Citric acid Eurofins internal enzymatic (DHC11)

[0176] Lactic acid Eurofins internal IC-EC (ID01V)

[0177] Sum of all sugars Eurofins internal method (DH900)

[0178] Galactose Eurofins internal method (DHSGA)

[0179] Glucose Eurofins internal method (DHSGL)

[0180] Lactose Eurofins internal method (DHSLA)

[0181] Calcium (Ca) ICP-OES (DS / EN ISO 11885m:2009) Phosphorous (P) ICP-OES (DS / EN ISO 11885 m:2009) Potassium (K) ICP-OES (DS / EN ISO 11885m:2009)

[0182] Sodium (Na) ICP-OES (DS / EN ISO 11885m:2009) Magnesium (Mg) ICP-OES (DS / EN ISO 11885m:2009)

[0183] Non-protein nitrogen (NPN) Kjeldahl (ISO 8968-4:2016 / IDF 20-4)

[0184] Milk composition Foss MilkoScan™ FT3

[0185] Gel strength TA.XTplus 100 Texture analyser (probe 490

[0186] mm2)

[0187] Viscosity Brookfield DV2TRVTJ0. spindle T-D. speed

[0188] 10 rpm

[0189]

[0190] The viscosity was measured as follows:

[0191] Samples were analyzed using a Brookfield DV2TRV Viscometer with spindle T-D, controlled via Rheocalc T software version 1.2.19. The profile was measured through the sample using a helipath at the center of the cup, with the spindle speed set to 10 rpm. Measurements were performed at 5°C in the original packaging. Data points were recorded every 2 seconds over a total measurement time of 2.5 min. The viscosity of each sample was calculated as the average of two measurements (one measurement per cup). The representative result was the time-averaged viscosity over the full interval last 2.5 min.

[0192] The gel strength was measured as follows:

[0193] Samples were analyzed using a TA.XTplus 100 Texture Analyser equipped with a 10 kg load cell and a P / 25P probe (25 mm DIA CYLINDER LAP PERSPEX, contact area: 490.87 mm2). Prior to testing, samples were equilibrated to the required temperature. The instrument was configured with a pre-test speed of 1 mm / s, a test speed of 1 mm / s, a post-test speed of 10 mm / s, a test distance of 25 mm, and a trigger force of 5 g. Measurements were performed directly on the samples in their cups.

[0194] Results:

[0195] Table 3 below shows the content of different components, as well as the gel strength and viscosity, measured in the 12 different samples after ultrafiltration (UF), but before fermentation. Ca refers to calcium, Na refers to sodium, Mg refers to magnesium and K refers to potassium.

[0196] Protein, fat, lactose and total solids results are measured by using Foss MilkoScan™ FT3. All other components listed in table 3 were analysed using the methods described in table 2.

[0197] Table 3: Composition of the milk after UF (UF retentate) before fermentation. Samp Protein Fat Lactos Total Ca Na Mg K le No. (%) (%) e (%) solids mg / kg mg / kg mg / kg mg / kg (%)

[0198] 1+2 10.1 0.23 4 15.43 2533.4 416.2 165.7 1208.4 3+4 9.93 0.34 3.86 15.25 2499.4 364.3 175.0 1675.8 5+6+ 9.9 0.18 4.4 15.50 2499.4 364.3 175.0 1675.8 7+8

[0199] 9+10 10 0.21 4.08 15.38 2670.8 393.9 173.0 1398.8

[0200]

[0201] 11+ 9.9 0.2 3.98 15.18 2638.3 338.8 174.4 1594.9 12

[0202]

[0203] As shown in table 3, the total calcium content in the acidified milk samples after UF step decreases as the pH is lowered. However, only a small difference was observed in the total calcium content for the two samples produced by citric acid and EDBM acidification methods at both pH values of 6.4 and 6.0. The other mineral contents such as potassium and magnesium were also found to decrease for the samples with acidified milk, especially for the sample where acidification was with EDBM. It is believed that this is due to the partial demineralization taking place during the EDBM process.

[0204] In table 4 below is the gel strength and final pH shown of a set yoghurt, i.e. after fermentation into a set yoghurt.

[0205] Table 4: The gel strength and final pH of the set yoghurt after the fermentation process

[0206] Sample No. Gel strength Final pH

[0207] (gram)

[0208] 1 410.3 4.34

[0209] 2 251.4 4.34

[0210] 3 824.0 4.31

[0211] 4 842.7 4.30

[0212] 5 837.2 4.30

[0213] 6 992.8 4.45

[0214] 7 1086.9 4.48

[0215] 8 964.0 4.47

[0216] 9 619.9 4.42

[0217] 10 867.1 4.42

[0218] 11 994.4 4.44

[0219] 12 1061.8 4.40

[0220]

[0221] From table 4, it is shown that acidification by using EDBM resulted in a lower gel strength as compared when acidification was with citric acid. In addition, table 4 shows that there is an effect on the gel strength of the set yoghurt of the temperature during heat treatment of the UF retentate before subjecting to fermentation. Table 4 shows that the lower the temperature is, the lower the gel strength is. This applies to the gel strength of the set yoghurt for all the acidification methods tested.

[0222] In general, table 4 shows that increasing the pasteurization temperature increases the gel strength for all pre-acidification values. Moreover, table 4 shows that the acidification method has a significant effect on the mineral profile in the concentrated milk before fermentation and the texture profile (e.g. gel strength) of the yoghurt. It was surprisingly found that the firmness of the yoghurt prepared by EDBM acidification was significantly lower as compared to acidification with citric acid for all the pre-acidification levels and regardless of the temperature of heat treatment.

[0223] Example 2:

[0224] In example 2, batches of the following were made:

[0225] no acidification before ultrafiltration

[0226] - acidification to pH 6.3 with EDBM before ultrafiltration

[0227] - acidification to pH 6.3 with addition of citric acid before ultrafiltration

[0228] The samples are prepared similarly to example 1 with skim milk as starting material. Pasteurized skim milk was acidified to pH 6.3 using either citric acid or the EDBM process. For the EDBM process. 250 kg of skim milk acted as the diluate. and 250 kg of a 1% (w / v) sodium chloride (NaCI) solution was used as the concentrate. The EDBM was conducted at a constant DC voltage of 75V. After acidification, the milk was ultrafiltered to reach a target protein concentration of approximately 10% (w / w). consistent with the procedure in Example 1.

[0229] The concentrated skim milk then underwent heat treatment at 85°C for a duration of 10 minutes. After the heat treatment, fermentation was carried out at 40°C using the Mild 2.0 lactic acid bacteria culture from Chr. Hansen A / S until the pH was reduced to 4.6. Following fermentation, the gel was disrupted and homogenized at a pressure of 30 bar to achieve a smooth consistency. The product was then cooled to 8°C post-homogenization and filled into cups. The cups were subsequently stored at 5°C for further analyses and sensory evaluation.

[0230] Analysis:

[0231] The content of protein, fat, lactose, total solids, calcium, lactic acid and citric acid were determined of skim milk, pre-acidified milk and UF retentate using Milkoscan. This is shown in table 5 below. The term "CA" refers to acidification with citric acid and "EDBM" refers to acidification with EDBM.

[0232] Table 6 shows the viscosity, pH and content of ash, chloride, citric acid, non-protein-nitrogen (NPN), protein, total solids, magnesium, sodium, potassium, calcium, phosphorous, lactose (anhydrous) sum of sugars, galactose, glucose, lactose, lactic acid and citric acid of fermented products that has been acidified with citric acid, with EDBM and not acidified. The fermented samples were analysed using the methods described in table 2.

[0233] The fermented product was smoothened after fermentation. Therefore, viscosity was measured using a Brookfield viscosimeter instead of the gel strength as in example 1.

[0234] Table 5: Composition of milk samples before and after UF

[0235] Metho Sample Fat Protein Total Lactos Calciu Lactic Citric d of g / 100 g / 100 solids e m acid acid acidify g g g / 100 g / 100 mg / kg g / 100 g / 100 g g g g No Skim milk 0.06 3.6 9.41 4.84 1400 <0.05 0.26 acidify UF ret. 0.08 10.02 15.53 4.49 3100 <0.05 0.20 CA Skim milk 0.06 3.66 9.48 4.71 1400 <0.05 0.24

[0236] UF ret. 0.12 10.04 15.48 4.35 2700 <0.05 0.25 EDBM Skim milk 0.08 3.84 9.11 4.36 1300 <0.05 0.17

[0237] UF ret. 0.13 10.09 15.29 4.06 2600 <0.05 0.16

[0238]

[0239] Table 6: Physicochemical analyses of high protein fermented products with no acidification and acidification using citric acid and acidification using EDBM.

[0240] Method of Units No Acidification Acidification acidify acidification with CA with EDBM Viscosity mPa*s 65718 67810 31524 pH

[0241] Ash g / lOOg 1.16 1.11 0.99 Chloride mg / lOOg 70 67 69

[0242] Citric acid g / lOOg 0.2 0.27 0.17

[0243] NPN g / lOOg 0.046 0.037 0.043 Protein g / lOOg 9.64 9.5 9.22 (N*6.38)

[0244] Total solids g / lOOg 15.15 14.97 14.31 Magnesium mg / lOOg 200 180 170 Sodium g / lOOg 0.035 0.033 0.043 Potassium mg / kg 1700 1600 1300 Calcium mg / kg 3100 2700 2600 Phosphorous mg / kg 2000 1800 1800 Lactose g / lOOg 1.63 1.96 1.62 (anhydrous)

[0245] Sum of g / lOOg 2.8 3.03 2.67 sugars

[0246] Galactose g / lOOg 1.2 1.0 0.9 Glucose g / lOOg <0.2 <0.2 <0.2 Lactose g / lOOg 1.6 2.0 1.7

[0247] Lactic acid g / lOOg 1.67 1.4 1.31 Citric acid g / lOOg 0.2 0.25 0.17

[0248]

[0249] Results:

[0250] Table 5 shows the results of composition of milk samples that have been preacidified using different methods (no acidification, acidification with citric acid and acidification with EDBM) before and after UF concentration (UF retentate).

[0251] Table 5 shows that the calcium concentration in the UF retentate was found to be the highest for an UF retentate of non-acidified milk and lowest for an UF retentate acidified using EDBM. The calcium content was comparable for the sample pre-acidified with citric acid and EDBM in line with example 1. Further, table 5 shows as expected that the citric acid concentration was higher for milk sample acidified with citric acid and was lower for EDBM.

[0252] Table 6 shows the physicochemical properties of high protein fermented products produced from pre-acidified milk samples. The ash content in the samples of fermented products obtained using EDBM for acidification was lower as compared to the samples where acidification was by using citric acid and un-acidified samples. This is believed to be due to partial demineralization taking place during EDBM process which is supported by reduction of the calcium, magnesium and potassium concentration in the EDBM treated samples compared to samples made from unacidified milk and milk acidified using citric acid.

[0253] The sodium concentration is slightly higher for EDBM sample which is believed to be due to leakage of sodium ions from the electrolyte and concentrate streams during EDBM process.

[0254] However, the most noticeable difference amongst the samples is on the viscosity. The sample of fermented product prepared from the pre-acidified milk using EDBM had the lowest viscosity as compared to samples of fermented product prepared from milk being acidified using citric acid and un-acidified milk. These results are in line with data on the gel strength of the set fermented products disclosed in example 1.

[0255] Example 3: Sensory analysis of fermented products

[0256] The samples of high protein fermented products from example 2 (shown in table 6) were also subjected to sensory analysis.

[0257] Samples of the different fermented products were given to a test panel consisting of 5 trained people. The test panel was trained ahead of the evaluation day and the test was blind test giving samples one-by-one. All samples were given twice to the test person. The samples were given to the test panel after cooling to 5°C and given a score on mouthfeel, syneresis, viscosity, creaminess, flavor intensity and acidity. The sensory scope of different parameters (1-10) is shown in table 7 below:

[0258] Table 7:

[0259] Pa ra meter No acidification Acidification with CA Acidification with EDBM

[0260] Smooth 4 4 6 appearance

[0261] Syneresis 3 3 2 Viscosity 7 7 6 Creamy 7 7 8 Overall 6 6 7 flavour

[0262] intensity

[0263] Acidity 7 6 5

[0264]

[0265] Further, the fermented product obtained from acidification with EDBM was found to be more creamy and fast melting than the fermented products obtained by acidification with citric acid and no acidification.

[0266] From the sensory analyses, the high protein fermented products produced using the EDBM process was found to be the most different compared to the fermented product obtained from un-acidified milk and from milk acidified using citric acid. The high protein fermented products produced using the EDBM process was found to have clear advantages in sensorial attributes such as lower viscosity, for example being fast melting and having smoother and creamier texture. It was also found to have less syneresis, and a milder taste (less acidity) compared to the samples of fermented products obtained by acidification with citric acid and no acidification.

Claims

Claims1. A process of preparing a fermented dairy product comprising the following process steps:i) providing a milk starting material;ii) adjusting pH of the milk starting material to be in the range of 5.8 to 6.5 by subjecting the milk starting material to electrodialysis using one or more bipolar membrane(s);iii) ultrafiltration (UF) of the pH adjusted milk starting material to obtain a UF retentate and a UF permeate;iv) fermenting the UF retentate obtained in step iii) to obtain a fermented dairy product.

2. The process according to claim 1, wherein the calcium content in the UF retentate obtained in step iii) is 30mg per gram protein or less.

3. The process according to any of the claims 1 to 2, wherein pH adjustment by using electrodialysis with a bipolar membrane of the milk starting material in step ii) is at a temperature in the range of 5°C to 30°C.

4. The process according to any of the claims 1 to 3, wherein the process does not comprise addition of an organic acid.

5. The process according to any of the claims 1 to 4, wherein the pH adjustment in step ii) is adjusting the pH of the milk starting material to be in the range of 6.0 to 6.3.

6. The process according to any of the claims 1 to 5, wherein the fermentation of the UF retentate in step iv) comprises addition of a lactic acid producing bacteria or kefir grains7. The process according to any of the claims 1 to 6, wherein the electrodialysis with bipolar membrane comprises one or more cationic exchange membrane(s) and one or more anionic exchange membrane(s).

8. The process according to any of the claims 1 to 7, wherein the milk starting material is selected from the group consisting of whole milk, low-fat milk, reduced fat milk, fat-free milk, buttermilk, reconstituted milk powder, lactose- reduce milk, low-lactose milk, lactose-free milk, heat treated milk, raw unfiltered milk, homogenized milk, mineral reduced milk, whey protein reduced milk, micellar casein isolate, micellar casein concentrate, and combinations thereof.

9. The process according to any of claims 1 to 8, wherein the milk starting material is an ultrafiltration permeate of milk and wherein the acidified ultrafiltration permeate of milk of step ii) is mixed with an ultrafiltration retentate before further ultrafiltration in step iii).

10. The process according to any of the claims 1 to 9, wherein the milk starting material comprises fat in an amount of 0.1% by weight or less.

11. The process according to any of the claims 1 to 10, wherein the fermented dairy product obtained is selected from the group consisting of skyr, fresh cheese, soft cheese, yoghurt, kefir, cultured buttermilk, cultured cream, sour milk, and sour cream.

12. A fermented dairy product comprising:- a protein content of at least 5% by weight- a calcium content of maximum 30 mg per gram protein- a potassium content of maximum 15 mg per gram proteinwherein the viscosity of the fermented dairy product is 45,000 mPa*s or below.

13. The fermented dairy product according to claim 12, wherein the fermented dairy product has a citric acid content of 0.22% by weight or less.

14. The fermented dairy product according to any of claims 12 or 13, wherein the fermented dairy product has a solid content in the range of 10% to 20% by weight.

15. The fermented dairy product according to any of claims 12 to 14, wherein the fermented dairy product has a gel strength of 800 gram or less.

16. The fermented dairy product according to any of the claims 12 to 15, wherein the fermented dairy product does not comprise any added chemical pH adjusting agent.

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