Production and separation of milk fractions by a final nanofiltration step

Abstract

A method for preparing a dairy composition using a final nanofiltration step is disclosed. Generally, the method further comprises an ultrafiltration step, and a reverse osmosis step, and optionally a diafiltration step.

Description

[Technical Field]

[0001] REFERENCE TO RELATED APPLICATIONS This application claims priority to U.S. Provisional Application No. 62 / 952,526, filed December 23, 2019, which was filed as a PCT international patent application on December 15, 2020, the disclosure of which is incorporated herein by reference in its entirety.

[0002] The present invention generally relates to the separation of dairy products into their protein, fat, carbohydrate, and mineral components using a combination of ultrafiltration, nanofiltration, diafiltration, and osmosis techniques, and also includes dairy compositions produced by blending dairy components in various combinations and proportions. [Background technology]

[0003] The membrane filtration process is a non-thermal technique for fractionating and concentrating fluids. When a fluid is passed through a semipermeable membrane under pressure, the components retained on the membrane's surface are called the retentate or concentrate, while the materials that pass through the membrane are collectively called the permeate. Because membrane technology generally does not involve heat or chemicals for fractionation or concentration, it does not adversely affect the properties of the fluid, benefiting milk and its components. When a fluid such as milk is fractionated using this membrane technology, proteins are typically not denatured, enzymes are not inactivated, vitamins are not destroyed, and reactions between proteins and sugars do not occur. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] U.S. Patent No. 7,169,428 [Patent Document 2] U.S. Patent No. 9,510,606 [Patent Document 3] U.S. Patent No. 9,538,770 [Non-patent literature]

[0005] [Non-Patent Document 1] Standard Methods for the examination of dairy products, 17th edition (2004), American Public Health Association, Washington DC Summary of the Invention

[0006] This Summary is provided to introduce a selection of concepts in a simplified form that are further described herein. This Summary is not intended to identify required or essential features of the claimed subject matter, nor is this Summary intended to be used to limit the scope of the claimed subject matter. [Means for solving the problem]

[0007] Consistent with embodiments of the present invention, a method for producing a dairy composition is disclosed, the method comprising: (i) ultrafiltration of a dairy product (a skim milk product or a fat-containing dairy product) at a temperature of about 3 to about 15° C. to produce a UF permeate fraction and a UF retentate fraction; (ii) subjecting the UF permeate fraction to a reverse osmosis process to produce an RO permeate fraction and an RO retentate fraction containing at least about 8% by weight of lactose (lactose or a derivative thereof); (iii) nanofiltration of the RO retentate fraction to produce an NF permeate fraction containing about 300 to about 800 ppm sodium and about 1500 to about 3000 ppm potassium, and an NF retentate fraction containing at least about 10% by weight of lactose (lactose or a derivative thereof); and (iv) separating the UF retentate fraction, DF / UF retentate fraction, the NF permeate fraction, the RO permeate fraction, the RO retentate fraction, and a fat-rich fraction. The method may further comprise diafiltering the UF retentate fraction to produce a DF / UF permeate fraction and the DF / UF retentate fraction. In some embodiments, the combining step may comprise combining at least the UF retentate fraction (or the DF / UF retentate fraction) and the NF permeate fraction, while in other embodiments, the combining step may comprise combining at least the fat-rich fraction, the UF retentate fraction (or the DF / UF retentate fraction), and the NF permeate fraction.

[0008] Both the foregoing summary and the following detailed description provide examples and are illustrative only. Accordingly, the foregoing summary and the following detailed description should not be construed as limiting. Furthermore, features or variations may be provided in addition to those described herein. For example, particular embodiments may be directed to various feature combinations and subcombinations described in the detailed description. [Brief explanation of the drawings]

[0009] [Figure 1] 1 shows a flow diagram of a separation process consistent with one embodiment of the present invention utilizing a final nanofiltration step. DETAILED DESCRIPTION OF THE INVENTION

[0010] definition In order to more clearly define the terms used herein, the following definitions are provided. Unless otherwise specified, the following definitions are applicable to the present disclosure. When a term is used in this disclosure but not specifically defined herein, the definition from the IUPAC Compendium of Chemical Terminology, 2nd Edition (1997) may apply unless it conflicts with any other disclosure or definition used herein or would obscure or disable any claim to which that definition applies. To the extent that any definition or usage provided by any document incorporated by reference herein conflicts with a definition or usage provided herein, the definition or usage provided herein controls.

[0011] The subject features are described herein such that different combinations of features may be envisioned within particular aspects and / or embodiments. For each aspect and / or embodiment and / or feature disclosed herein, all combinations that do not adversely affect the designs, compositions, processes and / or methods described herein are contemplated, regardless of whether a particular combination is explicitly described. Furthermore, unless otherwise expressly stated, any aspect and / or embodiment and / or feature disclosed herein can be combined to describe the inventive designs, compositions, processes and / or methods consistent with the present invention.

[0012] In this disclosure, compositions and methods are frequently described in terms of "comprising" various ingredients or steps, but the compositions and methods can equally "consist essentially of" or "consist of" various ingredients or steps, unless specified otherwise. For example, a dairy composition consistent with embodiments of the present invention can comprise a fat-rich fraction, a UF retentate fraction, and a NF permeate fraction; alternatively, it can consist essentially of a fat-rich fraction, a UF retentate fraction, and a NF permeate fraction; alternatively, it can consist of a fat-rich fraction, a UF retentate fraction, and a NF permeate fraction.

[0013] The terms "a," "an," and "the" are intended to include plural possibilities, e.g., at least one, unless otherwise specified. For example, "an ingredient" and "an additional milk fraction" are intended to include a mixture or combination of one ingredient and an additional milk fraction, or two or more ingredients and additional milk fractions, unless otherwise specified.

[0014] In the disclosed methods, the term "combining" includes contacting of components in any order, in any manner, and for any length of time, unless otherwise specified. For example, the components may be combined by blending or mixing.

[0015] Lactose-rich fraction (lactose-rich or derivatives thereof), milk sugar (lactose or derivatives thereof), and related terms are intended to include lactose and any derivative thereof, e.g., hydrolyzable, non-hydrolyzable, epimerized, isomerized, or converted to oligosaccharides, as would be recognized by one of skill in the art. Additionally, these terms are also intended to include glucose / galactose, which may result from the treatment of lactose with, for example, the enzyme lactase.

[0016] Although any methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present invention, exemplary methods and materials are described herein.

[0017] Various numerical ranges are disclosed herein. When any type of range is disclosed or claimed herein, the intent is to disclose or claim each possible number individually, including the endpoints of the range, and any subranges and combinations of subranges contained therein, which such ranges may reasonably encompass, unless otherwise specified. As a representative example, the present application discloses that a UF retentate fraction, in certain embodiments, may have about 9 to about 15% protein by weight. By disclosing that the protein content of a UF retentate fraction may be in the range of about 9 to about 15% by weight, the intent is to include that the protein content may be any amount within that range, e.g., about 9, about 10, about 11, about 12, about 13, about 14, or about 15% by weight. Furthermore, a UF retentate fraction may contain an amount of protein within any range of about 9 to about 15% by weight (e.g., about 10 to about 14% by weight), which also includes any combination of ranges between about 9 and about 15% by weight. Furthermore, whenever "about" a particular value is disclosed, the value itself is disclosed. Thus, disclosure of a protein content of about 9 to about 15% by weight also discloses a protein content of 9-15% by weight (e.g., 10-14% by weight), which also includes any combination of ranges therebetween. Similarly, all other ranges disclosed herein should be interpreted analogously to this example.

[0018] The term "about" means that an amount, size, formulation, parameter, and other quantity and characteristic is not exact, and need not be exact, but may be approximate, including being larger or smaller, as desired, to reflect tolerances, conversion factors, rounding, measurement error, etc., and other factors known to those skilled in the art. In general, an amount, size, formulation, parameter, or other quantity or characteristic is "about" or "approximate" whether or not expressly stated as such. The term "about" also includes different amounts due to different equilibrium conditions of the composition resulting from a particular initial mixture. Whether modified by the term "about," the claims include equivalents of the quantity. The term "about" can mean within 10% of the reported numerical value, and preferably within 5% of the reported numerical value. DETAILED DESCRIPTION OF THE INVENTION

[0019] Disclosed and described herein are methods for producing dairy compositions. Such methods can utilize a nanofiltration step after reverse osmosis as the final step in the milk fractionation process.

[0020] Without wishing to be bound by theory, the final nanofiltration step is believed to result in the recovery and use of more minerals, such as Ca, Mg, Na, and K, that would otherwise be lost. Thus, a significant utility of the methods disclosed herein is the extraction of additional minerals from the starting milk product, which can be used in the production of dairy compositions instead of being lost otherwise. In some cases, the amount of minerals in the NF permeate stream can unexpectedly range from about 0.35 to about 1 wt. %, or from about 0.4 to about 0.8 wt. %. Also advantageously, surprisingly high levels of sodium (about 300-800 or about 400-700 wt. ppm) and potassium (about 1500-3000 or about 2000-2500 wt. ppm) can be recovered in the NF permeate stream.

[0021] Another utility is an NF retentate stream that contains very high levels of milk sugar, e.g., lactose, and has reduced levels of other milk components, e.g., reduced protein content and / or reduced mineral content. The concentrated lactose stream can be used in pharmaceutical applications and to produce lactose powder, as well as for conversion to lactic acid, lactobionic acid, or ethanol.

[0022] Furthermore, by performing reverse osmosis prior to nanofiltration, a large milk water fraction (RO permeate) is formed that is substantially free of protein, milk sugar (lactose or its derivatives), fat, and minerals. This large RO permeate stream can be advantageously used throughout the production facility, for example, in the diafiltration of UF or NF retentates. Furthermore, the removal of large amounts of water allows for faster and more efficient nanofiltration operations.

[0023] Consistent with one embodiment of the present invention, a method of producing a dairy composition includes the steps of: (i) ultrafiltering a dairy product at a temperature of about 3 to about 15°C to produce a UF permeate fraction and a UF retentate fraction; (ii) subjecting the UF permeate fraction to a reverse osmosis process to produce an RO permeate fraction and an RO retentate fraction containing at least about 8% by weight of lactose (lactose or a derivative thereof); and (iii) nanofiltering the RO retentate fraction to produce a retentate fraction containing about 300 to about 800 ppm sodium and about 1500 to about 3000 ppm potassium. and (iv) combining at least two of the UF retentate fraction, the DF / UF retentate fraction, the NF permeate fraction, the RO permeate fraction, the RO retentate fraction, and the fat-rich fraction to form the dairy composition (or may consist essentially of, or consist of, (i), (ii), (iii), and (iv)). In some embodiments, the combining step may comprise combining at least the UF retentate fraction and the NF permeate fraction, while in other embodiments, the combining step may comprise combining at least the fat-rich fraction, the UF retentate fraction, and the NF permeate fraction. In these and other embodiments, the UF retentate fraction may be combined with RO permeate and diafiltered.

[0024] Generally, the process features (e.g., features of the dairy product, the ultrafiltration process and the resulting UF permeate and UF retentate fractions, the nanofiltration process and the resulting NF permeate and NF retentate fractions, the diafiltration process and the resulting DF / UF permeate and DF / UF retentate fractions, the reverse osmosis process and the resulting RO permeate and RO retentate fractions, among others, and the components that are combined to form the dairy composition) are described independently herein, and the features can be combined in any combination to further describe the disclosed methods. Furthermore, unless otherwise specified, other process steps may occur before, during, and / or after any of the steps recited in the disclosed methods. Furthermore, any dairy composition (e.g., a ready-to-consume finished dairy product) produced according to any of the disclosed methods is within the scope of the present disclosure and is included herein.

[0025] Filtration techniques (e.g., ultrafiltration, nanofiltration, diafiltration, etc.) can separate or concentrate components in a mixture—e.g., milk—by passing the mixture through a membrane system (or selective barrier) under appropriate conditions (e.g., pressure). Concentration / separation can thus be based on molecular size. The stream retained by the membrane is called the retentate (or concentrate). The stream that passes through the pores of the membrane is called the permeate. With reference to the disclosed method of producing a dairy composition, the method may include: (i) ultrafiltering a dairy product at a temperature of about 3 to about 15° C. to produce a UF permeate fraction and a UF retentate fraction; (ii) subjecting the UF permeate fraction to a reverse osmosis process to produce an RO permeate fraction and an RO retentate fraction containing at least about 8% by weight of lactose (lactose or a derivative thereof); (iii) nanofiltering the RO retentate fraction to produce an NF permeate fraction containing about 300 to about 800 ppm sodium and about 1500 to about 3000 ppm potassium, and an NF retentate fraction containing at least about 10% by weight of lactose (lactose or a derivative thereof); and (iv) combining at least two of the UF retentate fraction, the DF / UF retentate fraction, the NF permeate fraction, the RO permeate fraction, the RO retentate fraction, and the fat-rich fraction to form the dairy composition.

[0026] The dairy product of step (i) may comprise skim milk or alternatively whole milk (or may consist essentially of skim milk or alternatively whole milk, or may consist of skim milk or alternatively whole milk). In some embodiments, the disclosed methods further comprise separating (e.g., by centrifugation or microfiltration) raw or fresh milk (whole milk) into a dairy product (also called skim milk) and a fat-rich fraction (also called cream or butterfat). Raw or fresh milk (whole milk) may be cow's milk containing approximately 87% by weight water, 3-4% by weight protein, 4-5% by weight carbohydrates / lactose, 3-4% by weight fat, and 0.3-0.8% by weight minerals. When fresh or raw dairy products are separated into skim milk and a fat-rich fraction, the fat-rich fraction typically contains high levels of fat (e.g., 20-50% fat, or 30-50% fat by weight) and solids (e.g., 30-60% or 40-55% by weight), and frequently contains, but is not limited to, approximately 1.5-4% protein, 2-5% lactose, and 0.2-0.9% minerals by weight.

[0027] In step (i), ultrafiltration of dairy products can be performed using ultrafiltration membranes, typically having pore sizes in the 0.01 to 0.1 micron range. In the dairy industry, ultrafiltration membranes are frequently identified based on their molecular weight cutoff (MWCO) rather than pore size. The molecular weight cutoff of an ultrafiltration membrane can range from 1,000 to 100,000 daltons, or from 10,000 to 100,000 daltons. For example, dairy products can be ultrafiltered using a polymeric membrane system (ceramic membranes can also be used). The polymeric (or ceramic) membrane system may have a pore size configured such that substances having a molecular weight greater than about 1,000 daltons, greater than about 5,000 daltons, or greater than about 10,000 daltons are retained, while lower molecular weight species pass through. For example, a UF membrane system with a 10,000 dalton molecular weight cutoff can be used in the dairy industry to separate and concentrate milk proteins. In some embodiments, the ultrafiltration step utilizes a membrane system having a pore size in the range of about 0.01 to about 0.1 μm, and an operating pressure typically in the range of 15 to 150 psig, or 45 to 150 psig. Without limitation, the ultrafiltration step can frequently be carried out at a temperature in the range of about 3 to about 15° C., e.g., about 4 to about 12° C., or about 5 to about 10° C. Ultrafiltration at lower temperatures provides superior product quality and organoleptic properties compared to ultrafiltration at higher temperatures (e.g., about 25 to 50° C.); furthermore, no pasteurization step is required when low-temperature ultrafiltration is utilized.

[0028] In step (ii), some or all of the UF permeate fraction may be subjected to reverse osmosis to produce an RO permeate fraction and an RO retentate fraction (the RO retentate fraction containing at least about 8% by weight of lactose or its derivatives). Reverse osmosis is a microfiltration or concentration step in which substantially all remaining milk components are retained (RO retentate) and only water (RO permeate, milky water) passes through. Often, reverse osmosis membrane systems have a molecular weight cutoff well below 100 Da, so that components other than water are concentrated in the reverse osmosis step (e.g., minerals). Reverse osmosis generally involves membrane systems with pore sizes of about 0.001 μm or less. Operating pressures are typically in the range of 450 to 1500 psig, or 450 to 600 psig. Temperatures ranging from about 5 to about 45°C, or from about 15 to about 45°C, can be used.

[0029] In step (iii), some or all of the RO permeate fraction may be subjected to a nanofiltration process to produce an NF permeate fraction (containing about 300 to about 800 ppm sodium and about 1500 to about 3000 ppm potassium) and an NF retentate fraction (containing at least about 10% by weight of lactose or its derivatives). Nanofiltration in the dairy industry typically uses membrane elements that retain particles having molecular weights greater than approximately 100 to 300 Da. Nanofiltration is a pressure-driven process in which a liquid is forced through a membrane under pressure, retaining materials with a molecular weight greater than a specified cutoff while smaller particles pass through the membrane pores. To generally separate lactose from minerals in an influent stream, a pore size can be selected for maximum lactose retention. Like ultrafiltration, nanofiltration can simultaneously perform both concentration and separation.

[0030] Nanofiltration of the RO retentate fraction can be carried out using nanofiltration membranes having pore sizes typically in the 0.001 to 0.01 micron range, e.g., about 0.001 to about 0.008 μm. In some embodiments, the nanofiltration process utilizes a membrane system having pore sizes in the 0.001 to about 0.01 μm range, typically, but not limited to, at operating pressures ranging from 150 to 450 psig and operating temperatures ranging from about 10 to about 60° C. (or about 15 to about 45° C.).

[0031] Optionally, the UF retentate fraction—part or all of the UF retentate fraction produced in step (i)—may be diafiltered to produce a DF / UF permeate fraction and a DF / UF retentate fraction. The DF / UF permeate fraction may be combined with the UF permeate and then subjected to reverse osmosis, and the resulting RO retentate may then be nanofiltered to extract minerals and separate lactose (lactose or its derivatives). Typically, the diafiltration step is performed using an ultrafiltration membrane, as described above. However, other membranes may be used in the diafiltration step. In one embodiment, diafiltration of the UF retentate fraction may involve diafiltration of a mixture of the UF retentate fraction and water. In another embodiment, diafiltration of the UF retentate fraction may involve diafiltration of a mixture of the UF retentate fraction and RO permeate fraction. In yet another embodiment, diafiltration of the UF retentate fraction may involve diafiltration of a mixture of the UF retentate fraction, the RO permeate fraction, and water. These mixtures can utilize any suitable ratios or relative amounts of the UF retentate fraction, and the RO permeate fraction, and / or water. Frequently, diafiltration of the UF retentate fraction results in a DF / UF permeate fraction (containing lactose and minerals extracted from the UF retentate) and a DF / UF retentate fraction (protein-rich).

[0032] When the UF retentate fraction is mixed (diluted) with other components (e.g., water and / or the RO permeate fraction) prior to introduction into the ultrafiltration membrane system, the weight ratio of the other components to the UF retentate fraction frequently ranges, but is not limited to, from about 0.1:1 to about 1:1, from about 0.2:1 to about 0.8:1, or from about 0.3:1 to about 0.7:1. Diafiltration—using ultrafiltration membranes—can be performed at any suitable concentration ratio, non-limiting examples of which include from about 1.2 to about 5, from about 1.3 to about 4, from about 1.2 to about 3, or from about 2 to about 3.

[0033] Step (iv) of the method for producing a dairy composition includes combining at least two of a UF retentate fraction, a DF / UF retentate fraction, a NF permeate fraction, an RO permeate fraction, an RO retentate fraction, and a fat-rich fraction to form the dairy composition. Any combination of these components may be mixed or combined in any suitable relative proportions to form the dairy composition. In some embodiments, at least a UF retentate fraction and a NF permeate fraction may be combined, or at least a fat-rich fraction, a UF retentate fraction, and a NF permeate fraction may be combined. Optionally, an RO permeate fraction and / or water may be further added in the combining step. In other embodiments, at least a DF / UF retentate fraction and a NF permeate fraction may be combined, or at least a fat-rich fraction, a DF / UF retentate fraction, and a NF permeate fraction may be combined. Optionally, an RO permeate fraction and / or water may be further added in the combining step.

[0034] Further ingredients and / or additional milk fractions can also be added during the combining step. Additionally or alternatively, ingredients and / or additional milk fractions may be added to the dairy composition after the combining step. Non-limiting examples of suitable ingredients can include sugars / sweeteners, flavoring materials, preservatives (e.g., to prevent yeast or mold growth), stabilizers, emulsifiers, prebiotic substances, probiotic bacteria, vitamins, minerals, omega-3 fatty acids, phytosterols, antioxidants, or colorants, etc., as well as any mixture or combination thereof.

[0035] Additional milk fractions may be "ingredient-rich fractions," which is intended to include any fraction containing at least 15% more of a milk component (protein, lactose / sugar, fat, minerals) than found in cow's milk. For example, lactose-rich fractions may frequently contain about 6 to about 20% by weight of sugars (i.e., in any form, e.g., lactose, glucose, galactose, etc.), about 6 to about 18% by weight of sugars, or about 7 to about 16% by weight of sugars. Mineral-rich fractions may contain about 1 to about 20% by weight of minerals, about 1 to about 10% by weight of minerals, or about 1.5 to about 8% by weight of minerals. Fat-rich fractions may frequently contain about 8 to about 50% by weight of fat, about 20 to about 50% by weight of fat, or about 30 to about 45% by weight of fat.

[0036] These ingredient-rich milk fractions can be produced as described herein or by any technique known to those skilled in the art, for example, by the membrane filtration process disclosed in U.S. Patent Nos. 7,169,428, 9,510,606, and 9,538,770, which are incorporated herein by reference in their entireties. Additionally or alternatively, the ingredient-rich milk fraction (or milk fractions) can be produced by a process comprising mixing water with powdered ingredients (e.g., protein powder, lactose powder, mineral powder, etc.).

[0037] Any suitable vessel and conditions can be used for any combining step disclosed herein, and such steps can be performed batchwise or continuously. As one example, the ingredients can be combined in a suitable vessel (e.g., a tank, silo, etc.) under atmospheric pressure, optionally with stirring or mixing, and optionally with an ingredient(s) and / or an additional milk fraction(s), to form a set of finished dairy compositions. As another example, the ingredients can be continuously combined under light pressure (e.g., 5-50 psig) in a pipe or other suitable vessel, optionally mixed with ingredients and / or additional milk fractions, and the finished dairy composition can be transferred to a storage tank or filled into containers for retail distribution and sale. Exemplary systems that can be used for this continuous combining, mixing, and / or packaging can include a tetra aldose system and a tetra flexidose system. Other suitable methods, systems, and apparatus for combining ingredients and other ingredients and / or milk fractions will be readily apparent from this disclosure.

[0038] If desired, lactase enzyme may be added to the dairy product prior to ultrafiltration, or to each of the ingredients prior to the combining step, or to the resulting dairy composition. As described herein, the ingredients may be combined in any suitable ratio to form the dairy composition, and optionally, any suitable ingredients and / or additional milk fractions may be added in step (iv). Additionally or alternatively, any suitable ingredients and / or additional milk fractions may be added to the dairy composition after the combining step.

[0039] Consistent with embodiments of the present invention, the UF retentate fraction may be treated with a lactase enzyme prior to the combining step, if desired. Similarly, the DF / UF retentate fraction may be treated with a lactase enzyme prior to the combining step, if desired. Additionally or alternatively, lactase enzyme may be added during step (iv), or the dairy composition may be treated with a lactase enzyme after step (iv). In such cases, the lactose content may be reduced to less than about 1%, less than about 0.5%, less than about 0.2%, or less than about 0.1% by weight.

[0040] Optionally, the method may further comprise microfiltration of the dairy product (e.g., skim milk) prior to the ultrafiltration step, resulting in a MF permeate fraction and a MF retentate fraction. In such cases, step (i) may comprise ultrafiltration of the MF permeate fraction to produce a UF permeate fraction and a UF retentate fraction. Microfiltration may be performed using microfiltration membranes having relatively large pore sizes, typically in the 0.1 to 10 micron range, e.g., pore sizes in the range of about 0.2 to about 2 μm, or about 0.1 to about 0.2 μm. In some embodiments, the microfiltration step utilizes a membrane system having a pore size in the range of about 0.1 to about 0.2 μm, typically at an operating pressure of less than about 75 psig (e.g., 10 to 15 psig) and an operating temperature ranging from about 5 to about 60°C (or about 35 to about 55°C), but is not limited thereto.

[0041] Frequently, microfiltration membranes can be used in the dairy industry to remove bacteria, bacterial spores, somatic cells, and other extraneous floating matter from fluid milk, thereby improving the quality and shelf life of the resulting dairy product. Microfiltration membranes can be used as an alternative to centrifugation to separate fat from cheese or whey cheese, and to separate milk fat from fluid milk.

[0042] The protein content of the UF retentate fraction and the DF / UF retentate fraction can independently be at least about 5%, at least about 6%, at least about 7%, at least about 8%, or at least about 9% protein by weight. Exemplary, non-limiting ranges for the protein content of the UF retentate and the DF / UF retentate can independently include about 5 to about 20% protein by weight, about 6 to about 18% protein by weight, or about 9 to about 15% protein by weight.

[0043] Similarly, the lactose (lactose or derivatives thereof) content of the UF permeate fraction, UF retentate fraction, DF / UF permeate fraction, and DF / UF retentate fraction can independently be, but is not limited to, about 7% by weight or less, or about 6% by weight or less, but can be about 3% by weight or more, or about 3.5% by weight or more.

[0044] The lactose (lactose or its derivatives) content of the NF retentate fraction can be, but is not limited to, at least about 8%, at least about 10%, at least about 14%, at least about 17%, or at least about 20% lactose (lactose or its derivatives) by weight. Exemplary, non-limiting ranges for the lactose content of the NF retentate fraction can include about 10% to about 28%, about 15% to about 28%, about 15% to about 25%, about 20% to about 28%, or about 20% to about 25% lactose (e.g., lactose or its derivatives) by weight. The solids content of the NF retentate fraction is generally at least about 15%, at least about 20%, or at least about 22%, and frequently can range up to 25-30% by weight. The NF retentate fraction contains minimal amounts of protein, typically less than about 1%, less than about 0.7%, less than about 0.5%, or less than about 0.3% protein by weight. The NF retentate fraction frequently contains from about 0.8 to about 2% by weight minerals, for example, from about 1 to about 1.8% by weight minerals.

[0045] The NF permeate fraction generally contains less than 1% by weight solids and only minimal amounts of milk sugar (e.g., lactose) and protein. Surprisingly, the NF permeate contains significant amounts of minerals, frequently ranging from about 0.35 to about 1% by weight, e.g., from about 0.4 to about 0.8% by weight. Also advantageously, high levels of sodium—about 300 to about 800 ppm, or about 400 to about 700 ppm—and potassium—about 1500 to about 3000 ppm, or about 2000 to about 2500 ppm—can be present in the NF permeate stream. These ppm amounts are ppm by weight.

[0046] The RO retentate fraction after the reverse osmosis step contains significant amounts of lactose (lactose or its derivatives), e.g., at least about 8% by weight or at least about 10% by weight, frequently up to about 14-18% by weight, and minerals in the range of 0.6-1.8% by weight or in the range of 0.7-1.2% by weight. Generally, the RO permeate (milk water) fraction is substantially free of milk components—fat, protein, milk sugar (e.g., lactose), and minerals. For example, the milk water fraction may contain about 0.1% or less by weight of lactose (e.g., lactose) and about 0.1% or less by weight of minerals. Furthermore, the milk water fraction may contain about 0.1% or less by weight of fat, about 0.1% or less by weight of protein, and at least about 95% by weight of water, at least about 98% by weight of water, at least about 99% by weight of water, or at least about 99.5% by weight of water.

[0047] An illustrative, non-limiting example of a suitable separation process 10 consistent with embodiments of the process of the present invention is shown in Figure 1. First, fresh whole milk (raw milk) 15 is separated 20 into cream 28 and skim milk product 22. The skim milk product 22 is then ultrafiltered 30, for example, through a polymeric membrane system described herein, to produce a UF retentate 38, often referred to as a protein-rich milk fraction, and a UF permeate 32 containing lactose (lactose or its derivatives) and minerals. The UF permeate 32 is then subjected to reverse osmosis 40 to produce an RO retentate 48 containing lactose (lactose or its derivatives) and minerals, and an RO permeate 42 consisting essentially of water. The RO retentate 48 is then nanofiltered 50 to produce an NF permeate 52 (rich in minerals) and an NF retentate 58 (rich in lactose). Optionally, some or all of the UF retentate 38 in FIG. 1 is combined with the RO permeate 42 and diafiltered 60 to produce a DF / UF permeate fraction 62 and a DF / UF retentate fraction 68 (which is protein-rich).

[0048] 1 is formed by combining or mixing UF retentate fraction 38, DF / UF retentate fraction 68, NF permeate fraction 52, RO permeate fraction 42, and cream 28 (a fat-rich fraction) in any suitable proportions. Optionally, the ingredients may be treated with lactase enzymes 72, 74, 76 before mixing the ingredients or after forming dairy composition 80. Dairy composition 80 is then heat treated 85 before being cooled and packaged 90.

[0049] Consistent with embodiments of the improved methods for producing dairy compositions disclosed herein, these methods can further include, if desired, treating the respective dairy composition with a lactase enzyme, such that the lactose content can be reduced to less than about 1%, less than about 0.5%, less than about 0.2%, or less than about 0.1% by weight.

[0050] Additionally, the methods may further comprise the step of heat-treating the dairy composition. In one embodiment, the heat-treating step may comprise pasteurization at a temperature ranging from about 80°C to about 95°C for a time ranging from about 2 to about 15 minutes. In another embodiment, the heat-treating step may comprise UHT sterilization at a temperature ranging from about 135°C to about 145°C for a time ranging from about 1 to about 10 seconds. In yet another embodiment, the heat-treating step may comprise ultra-UHT sterilization at a temperature ranging from about 148°C to about 165°C for a time ranging from about 0.05 to about 1 second (e.g., approximately 0.1 seconds at 155°C). Other suitable pasteurization or sterilization temperature and time conditions will be readily apparent from the present disclosure. Furthermore, the present invention is not limited by the method or apparatus used to perform the pasteurization / sterilization step; any suitable technique and apparatus may be used, whether operated batchwise or continuously.

[0051] In some embodiments of the present invention, the improved method for producing a dairy composition may further include, after the heat treatment step, packaging the dairy composition (aseptically or otherwise) in any suitable container under any suitable conditions. Thus, after combining the various components, ingredients, and additional milk fractions described herein to form the dairy composition, the dairy composition can be packaged in a container under aseptic conditions (or non-aseptic conditions). Any suitable container that can be used for retail distribution and / or sale of dairy products can be used. Illustrative, non-limiting examples of typical containers include cups, bottles, bags, pouches, etc. The container can be made of any suitable material, such as glass, metal, plastic, etc., and combinations thereof.

[0052] Without limitation, the dairy composition may have a protein content of about 1 to about 15% by weight, or about 3 to about 10% by weight. Additionally or alternatively, the dairy composition may have a fat content of about 0.05 to about 10% by weight, or about 0.1 to about 5% by weight. Additionally or alternatively, the dairy composition may have a mineral content of about 0.5 to about 2% by weight. Additionally or alternatively, the dairy composition may have a lactose content of about 4% or less by weight.

[0053] Representative, non-limiting examples of dairy compositions consistent with the present invention may contain about 0.5% or less fat, about 2 to about 15% protein, about 0.5 to about 2% minerals, and about 4% or less lactose by weight. Another representative, non-limiting example of a dairy composition consistent with the present invention may contain about 0.5 to about 1.5% fat, about 2 to about 15% protein, about 0.5 to about 2% minerals, and about 4% or less lactose by weight. Yet another representative, non-limiting example of a dairy composition consistent with the present invention may contain about 1.5 to about 2.5% fat, about 2 to about 15% protein, about 0.5 to about 2% minerals, and about 4% or less lactose by weight. Additionally, other representative, non-limiting examples of dairy compositions consistent with the present invention may contain from about 2.5 to about 5% by weight fat, from about 2 to about 15% by weight protein, from about 0.5 to about 2% by weight minerals, and up to about 4% by weight lactose.

[0054] Further non-limiting examples of typical dairy compositions that may be produced by the methods disclosed herein include whole milk, low-fat milk, skim milk, buttermilk, flavored milk, low-lactose milk, high-protein milk, lactose-free milk, ultrafiltered milk, microfiltered milk, concentrated milk, evaporated milk, high-protein milk, high-calcium milk, and reduced sugar milk, etc. [Example]

[0055] The present invention is further illustrated by the following examples, which should not be construed in any way as limitations imposed on the scope of the present invention. After reading the description herein, various other aspects, embodiments, modifications, and equivalents thereof may occur to those skilled in the art without departing from the spirit of the invention or the scope of the appended claims.

[0056] Total solids (wt%) were determined using a CEM Turbo Solids / Moisture Analyzer (CEM Corporation, Matthews, North Carolina) according to test method SMEDP 15.10 C. Ash is the residue remaining after combustion to constant weight at 550°C in a suitable apparatus; such treatment at 550°C typically removes all organic matter, and the residue is primarily minerals (Standard Methods for the examination of dairy products, 17th ed. (2004), American Public Health Association, Washington, DC). Ash testing was performed using a Phoenix (CEM microwave oven), with samples heated to 550°C for 30 minutes. Ash content (or mineral content) was determined in wt%.

[0057] The specific contents of Ca, Mg, Na, and K were determined using a Perkin Elmer atomic absorption spectrophotometer. Samples were treated with trichloroacetic acid to precipitate proteins, and the filtrate was analyzed by atomic absorption spectrophotometer. Protein, fat, and lactose contents were determined by AOAC (Association of Official Analytical Chemists) methods.

[0058] In Example 1, raw milk (below 5°C) was separated into a fat-rich fraction (cream) and a non-fat fraction (skim milk or skim milk) using a centrifuge, following the process outlined in Figure 1. The centrifugation step was carried out at a temperature below 5°C. The skim milk at 5°C was then fractionated into a protein-rich fraction (UF retentate) and a lactose-rich fraction (UF permeate) by passing it through a UF membrane with a pore size that retained all molecules with a molecular weight greater than 10,000 Daltons (Da) in the UF retentate. The UF retentate had an average protein content of 11.9% by weight and a fat content of 0.4% by weight. The UF permeate had a total solids content of 5.62-5.77% by weight, protein content of 0.10-0.15% by weight, ash content of 0.46-1.15% by weight, and a pH range of 6.7-6.9. The UF permeate was concentrated in an RO unit (GEA Model R Pilot Unit, GEA Process Engineering Inc.) containing an RO spiral-wound polymer element (Koch Membranes, 0.95 meter long and 0.095 meter diameter). The temperature during the RO process varied from 6 to 19°C under a pressure of 400 to 500 psig. The RO concentrate (RO retentate) was then decalcified in an NF system (GEA Model R Pilot Unit, GEA Process Engineering Inc.) using an NF membrane element (NF-200, spiral-wound membrane element, molecular weight cutoff 200 Da, 3-inch diameter, 0.95 meter long; 0.095 meter diameter) at temperatures ranging from 12 to 26°C.

[0059] Table I summarizes the average composition of each of the UF permeate, UF retentate, RO permeate, RO retentate, NF retentate, and NF permeate fractions during the 8-hour experiment of Example 1. Because the mineral content (wt%) in Table I was generally similar to the ash content (wt%), the results of the ash test are used to quantify the total mineral content in this disclosure. Table I also summarizes the average Ca, Mg, Na, and K content in ppm by weight for each of the milk fractions.

[0060] Dairy compositions were produced by blending UF retentate, NF permeate, RO concentrate, RO permeate, and cream. Commercially available lactase enzyme was added to the dairy compositions for 16 hours at 4°C prior to heat treatment to convert lactose to glucose and galactose. Table II summarizes dairy compositions prepared using the milk fractions from Example 1 and the comparative milk fractions (prepared using UF, then NF, then RO). Because the goal was to obtain dairy compositions that were substantially identical, slightly different blends were used for the comparative example and Example 1. A panel of six people informally evaluated the sensory attributes of the samples using a triangle discrimination test (i.e., panelists were presented with one different sample and two similar samples and instructed to taste each sample and identify the different sample). The panel was unable to distinguish any differences between the composition of Example 1 and the comparative composition.

[0061] Table III summarizes Constructive Example 2, a simulated experiment using UF / RO / NF, and Table IV summarizes a simulated comparative experiment using conventional UF / NF / RO. These simulations were performed to provide a direct comparison between the UF / RO / NF and UF / NF / RO processes and to demonstrate the utility of the UF / RO / NF process of Example 2, in which reverse osmosis precedes the final nanofiltration step. Surprisingly and advantageously, the UF / RO / NF process of Example 2 can recover more water (for use in other parts of the manufacturing facility without the need to purchase water), recover more minerals, and result in a more concentrated lactose stream than a conventional UF / NF / RO process.

[0062] [Table 1]

[0063] [Table 2]

[0064] [Table 3]

[0065] [Table 4]

[0066] [Explanation of symbols]

[0067] 10 Separation process 15 Fresh whole milk (raw milk) 20 separation 22 Skimmed dairy products 28 Cream 30 Ultrafiltration 32 UF permeate 38 UF retentate 40 Reverse Osmosis 42 RO permeate 48 RO retentate 50 Nanofiltration 52 NF permeate 58 NF retentate 60 Diafiltration 62 DF / UF permeate fraction 68 DF / UF retentate fraction 72 Lactase enzyme 74 Lactase Enzyme 76 Lactase Enzyme 80 Dairy Composition 85 Heat Treatment 90 Cooling and Packaging

Claims

1. (i) ultrafiltering the dairy product at a temperature of 3 to 15°C to produce a UF permeate fraction and a UF retentate fraction; (ii) subjecting the UF permeate fraction to a reverse osmosis process to produce an RO permeate fraction and an RO retentate fraction containing at least 8% lactose by weight. (iii) nanofiltration of the RO retentate fraction; an NF permeate fraction containing 300 to 800 ppm sodium and 1500 to 3000 ppm potassium; an NF retentate fraction containing at least 10% by weight of lactose; A process for producing (iv) combining at least two of the UF retentate fraction, the DF / UF retentate fraction, the NF permeate fraction, the RO permeate fraction, the RO retentate fraction, and the fat-rich fraction to form a dairy composition.

1. A method for producing a dairy composition comprising:

2. 2. The method of claim 1, wherein the lactose content of the RO retentate fraction is 8 to 18% by weight, 8 to 16% by weight, or 10 to 14% by weight.

3. 3. The method of claim 1 or 2, wherein the lactose content of the NF retentate fraction is 10 to 28%, 15 to 28%, 15 to 25%, 20 to 28%, or 20 to 25% by weight.

4. 4. The method of claim 1, wherein the total solids content of the NF retentate fraction is 15 to 30%, 20 to 30%, 20 to 28%, 22 to 30%, or 22 to 28% by weight.

5. 5. The method of claim 1, wherein the mineral content of the NF retentate fraction is 0.8 to 2% by weight, or 1 to 1.8% by weight.

6. 6. The method according to any one of claims 1 to 5, wherein the mineral content of the NF permeate fraction is from 0.35 to 1% by weight, or from 0.4 to 0.8% by weight.

7. 7. The method according to any one of claims 1 to 6, wherein the potassium content of the NF permeate fraction is between 2000 and 2500 ppm.

8. 8. The process according to any one of claims 1 to 7, wherein the sodium content of the NF permeate fraction is between 400 and 700 ppm.

9. 9. The method of claim 1, wherein the protein content of the UF retentate fraction is at least 9% by weight and the protein content of the DF / UF retentate fraction is at least 9% by weight.

10. 10. The method according to any one of claims 1 to 9, wherein the lactose content of the UF permeate fraction and / or the UF retentate fraction is 3.5 to 6% by weight.

11. 11. The method according to any one of claims 1 to 10, wherein the lactose content of the DF / UF permeate fraction and / or the DF / UF retentate fraction is 3.5 to 6% by mass.

12. 12. The method according to any one of claims 1 to 11, wherein the dairy product is ultrafiltered at a temperature of from 4 to 12°C, or from 5 to 10°C.

13. 13. The method of any one of claims 1 to 12, wherein the combining step comprises combining (a) the UF retentate fraction and the NF permeate fraction, or (b) the fat-rich fraction, the UF retentate fraction, and the NF permeate fraction.

14. 14. The method of any one of claims 1 to 13, further comprising diafiltering the UF retentate fraction to produce a DF / UF permeate fraction and a DF / UF retentate fraction.

15. 15. The method of claim 14, wherein the diafiltration of the UF retentate fraction comprises diafiltration of a mixture comprising the UF retentate fraction and the RO permeate fraction, further comprising water, or a mixture comprising the UF retentate fraction and the RO permeate fraction, but excluding water.

16. 16. The method of claim 14 or 15, wherein the combining step comprises combining (a) a DF / UF retentate fraction and a NF permeate fraction, or (b) a fat-rich fraction, a DF / UF retentate fraction, and a NF permeate fraction.

17. 17. The method of any one of claims 1 to 16, further comprising separating raw milk into skim milk and a fat-rich fraction.

18. 18. The method of any one of claims 1 to 17, wherein the combining step further comprises adding water to produce a dairy composition.

19. 19. The method of any one of claims 1 to 18, wherein the dairy product comprises skim milk or whole milk.

20. 20. The method of any one of claims 1 to 19, wherein the UF retentate fraction is treated with a lactase enzyme before the combining step, or the DF / UF retentate fraction is treated with a lactase enzyme before the combining step, or the method further comprises treating the dairy composition with a lactase enzyme, or any combination thereof.

21. 21. The method of any one of claims 1 to 20, further comprising microfiltration of the dairy product prior to step (i).

22. 22. The method of any one of claims 1 to 21, wherein the dairy composition has a fat content of 0.05 to 10% by weight, or 0.1 to 5% by weight.

23. 23. The method of any one of claims 1 to 22, wherein the dairy composition has a protein content of 1 to 15% by weight, or 3 to 10% by weight.

24. 24. The method according to any one of claims 1 to 23, wherein the dairy composition has a mineral content of 0.5 to 2% by weight.

25. 25. The method of any one of claims 1 to 24, wherein the dairy composition has a lactose content of not more than 4% by weight.

26. 26. The method of any one of claims 1 to 25, wherein the dairy composition is whole milk, low-fat milk, skim milk, buttermilk, flavored milk, low-lactose milk, high-protein milk, lactose-free milk, ultrafiltered milk, microfiltered milk, concentrated milk, evaporated milk, or high-protein, high-calcium, and low-sugar milk.

27. 27. The method of any one of claims 1 to 26, wherein the combining step further comprises adding ingredients, the ingredients comprising sugars / sweeteners, flavoring materials, preservatives, stabilizers, emulsifiers, prebiotic substances, probiotic bacteria, vitamins, minerals, omega-3 fatty acids, phytosterols, antioxidants, colorants, or any combination thereof.

28. 28. The method of any one of claims 1 to 27, further comprising the step of heat treating the dairy composition.

29. 29. The method of claim 28, wherein the heat treatment step comprises UHT sterilization at a temperature in the range of 135°C to 145°C for a time in the range of 1 to 10 seconds.

30. 29. The method of claim 28, wherein the heat treatment step comprises pasteurization at a temperature in the range of 80°C to 95°C for a time in the range of 2 to 15 minutes.

31. 29. The method of claim 28, wherein the heat treatment step comprises UHT sterilization at a temperature in the range of 148°C to 165°C for a time in the range of 0.05 to 1 second.

32. 32. The method of any one of claims 1 to 31, further comprising packaging the dairy composition in a container.

33. 33. The method of any one of claims 1 to 32, wherein the amount of water recovered from the dairy product is greater than the amount obtained by an otherwise identical process in which nanofiltration is performed before reverse osmosis.

34. 34. The method of any one of claims 1 to 33, wherein the amount of minerals in the NF permeate fraction is greater than the amount of minerals in the RO retentate fraction obtained by an otherwise identical process in which nanofiltration is performed before reverse osmosis.

35. 35. The method of any one of claims 1 to 34, wherein the concentration of lactose in the NF retentate fraction is higher than the concentration in the NF retentate fraction obtained by an otherwise identical process in which nanofiltration is performed before reverse osmosis.

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