Production and separation of milk fractions with final nanofiltration step

Abstract

The present invention discloses a method for preparing a milk composition using a final nanofiltration step. Typically, the method also comprises an ultrafiltration step and a reverse osmosis step and optionally a diafiltration step.

Description

[0001] Citation to Related Applications

[0002] This application was filed as a PCT international patent application on December 15, 2020, and claims priority to U.S. Provisional Patent Application No. 62 / 952,526 filed on December 23, 2019, the disclosure of which is incorporated herein by reference in its entirety. Background of the Invention

[0004] The present invention generally relates to the separation of milk products into protein, fat, carbohydrate and mineral components using a combination of ultrafiltration, nanofiltration, diafiltration and osmosis techniques. Also contemplated are milk compositions produced by mixing milk components in various combinations and proportions.

[0005] Membrane filtration methods are non-thermal fractionation and concentration techniques for fluids. When a fluid is passed through a semipermeable membrane under pressure, the components retained on the membrane surface are referred to as the retentate or concentrate, while the material that passes through the membrane is collectively referred to as the permeate. Membrane techniques generally do not involve heat or chemicals for fractionation or concentration, and therefore do not adversely affect the properties of the fluid, which is beneficial to milk and its components. When fluids (such as milk) are fractionated by these membrane techniques, proteins are generally not denatured, enzymes are not inactivated, vitamins are not destroyed, and reactions between proteins and sugars do not occur. SUMMARY OF THE INVENTION

[0007] This summary is provided to introduce a selection of some concepts further described herein in a simplified form. This summary is not intended to identify required or essential features of the claimed subject matter. This summary is also not intended to be used to limit the scope of the claimed subject matter.

[0008] Consistent with embodiments of the present invention, a method for preparing a dairy composition is disclosed, and the method may include (i) ultrafiltration of a dairy product (skim dairy product or dairy product containing fat) 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 step to produce an RO permeate fraction and an RO retentate fraction containing at least about 8% by weight of milk sugar (lactose or its derivatives), (iii) nanofiltration of the RO retentate fraction to produce a NF permeate fraction containing about 300 to about 800 ppm of sodium and about 1500 to about 3000 ppm of potassium, and a NF permeate fraction containing at least about 10% by weight of milk sugar (lactose or its derivatives). The method further comprises the steps of diafiltering the UF retentate fraction to produce a DF / UF permeate fraction and a 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.

[0009] Both the preceding summary and the following detailed description provide examples and are illustrative only. Therefore, the preceding summary and the following detailed description should not be considered restrictive. In addition, features or variations other than those set forth herein may also be provided. For example, certain embodiments may relate to various feature combinations and sub-combinations described in the detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 A schematic flow diagram of a separation process utilizing a final nanofiltration step, consistent with one embodiment of the present invention, is shown.

[0012] definition

[0013] In order to more clearly define the terms used herein, the following definitions are provided. Unless otherwise indicated, the following definitions apply to the present invention. If a term is used in the present invention but is not specifically defined herein, the IUPAC Compendium of Chemical Terminology, 2nd Edition (1997) may be used. ndEd (1997)), so long as that definition does not conflict with any other disclosure or definition applied herein or render uncertain or unenforceable any claim to which that definition applies. To the extent any definition or usage provided by any document incorporated by reference conflicts with the definition or usage provided herein, the definition or usage provided herein controls.

[0014] In this article, the features of the subject matter are described so that in particular aspects and / or embodiments, combinations of different features can be envisioned. For each aspect and / or embodiment and / or feature disclosed herein, with or without an explicit description of a particular combination, all combinations that do not adversely affect the design, composition, process and / or method described herein are considered. In addition, unless otherwise explicitly stated, any aspect and / or embodiment and / or feature disclosed herein can be combined to describe an inventive design, composition, process and / or method consistent with the present invention.

[0015] In the present invention, although compositions and methods are often described in a manner of "comprising" various components or steps, unless otherwise specified, the compositions and methods may also be "consisting essentially of" or "consisting of" various components or steps. For example, a milk composition consistent with an embodiment of the present invention may comprise the following fractions; alternatively, may be substantially divided into the following fractions; or alternatively, may be composed of the following fractions: a fat-rich fraction, a UF retentate fraction, and a NF permeate fraction.

[0016] Unless otherwise stated, the terms "a", "an" and "the" are intended to include plural alternatives, e.g., at least one alternative. For example, unless otherwise stated, disclosure of "an ingredient" and "an additional milk fraction" is intended to encompass one ingredient and one additional milk fraction, or a mixture or combination of more than one ingredient and a mixture or combination of more than one additional milk fraction.

[0017] In the disclosed methods, unless otherwise indicated, the term "combining" encompasses contacting the components in any order, in any manner, and for any length of time. For example, the components can be combined by blending or mixing.

[0018] Lactose (milk sugar) rich fraction (enriched in lactose (lactose) or its derivatives), lactose (milk sugar) (lactose (lactose) or its derivatives) and related terms are meant to cover lactose and any derivatives thereof, e.g., hydrolyzed, unhydrolyzed, epimerized, isomerized or converted to oligosaccharides, as will be appreciated by those skilled in the art. In addition, these terms are also meant to cover glucose / galactose, such as can be produced by treating lactose with lactase.

[0019] Although any methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present invention, the typical methods and materials are described herein.

[0020] A variety of numerical ranges are disclosed herein. Unless otherwise stated, when any type of scope is disclosed or claimed herein, it is intended to disclose or claim individually each possible number that such a scope can reasonably cover, including the endpoints of the scope and any sub-ranges and combinations of sub-ranges covered therein. As a representative example, the present application discloses that UF retentate fractions can have about 9 to about 15 % by weight of protein in certain embodiments. By disclosing that the protein content of the UF retentate fraction can be in the range of about 9 to about 15 % by weight, it is intended to record that the protein content can be any amount within the range, and for example can be equal to about 9, about 10, about 11, about 12, about 13, about 14 or about 15 % by weight. In addition, the UF retentate fraction can contain the protein amount in any range of about 9 to about 15 % by weight (for example, about 10 to about 14 % by weight), and this also includes any combination of the scope of about 9 to about 15 % by weight. In addition, in all cases, when disclosing "about" a particular value, the value itself is disclosed. Therefore, the disclosure of a protein content of about 9 to about 15 wt % also discloses a protein content of 9 to 15 wt % (e.g., 10 to 14 wt %), and this also includes any combination of ranges of 9 to 15 wt %. Likewise, all other ranges disclosed herein should be interpreted in a manner similar to this example.

[0021] The term "about" means that the amount, size, formula, parameter and other quantities and characteristics are not and need not be exact, but may be approximate, including increasing or decreasing as needed, reflecting tolerances, conversion factors, rounding, measurement errors, etc., and other factors known to those skilled in the art. Generally, whether or not explicitly stated, the amount, size, formula, parameter or other quantity or characteristic is "about" or "approximate". The term "about" also covers differences in quantity due to different equilibrium conditions of the composition obtained from a particular initial mixture. Whether or not modified by the term "about", the claims include equivalents of the quantity. The term "about" can mean within 10% of the reported value, preferably within 5% of the reported value. DETAILED DESCRIPTION OF THE INVENTION

[0023] Disclosed and described herein are methods for preparing dairy compositions. Such methods may utilize a nanofiltration step as the last step in the milk fractionation process after reverse osmosis.

[0024] Although not wishing to be bound by theory, it is believed that the final nanofiltration step results in the recovery and use of more minerals, such as Ca, Mg, Na and K, which otherwise might be lost. Thus, a significant benefit of the methods disclosed herein is that additional minerals are extracted from the starting milk product, and these minerals can be used to produce a dairy composition, rather than being lost otherwise. In some cases, unexpectedly, the amount of minerals in the NF permeate stream can be in the range of about 0.35 to about 1 wt % or about 0.4 to about 0.8 wt %. In addition, surprisingly high levels of sodium (~300-800 or ~400-700 ppm by weight) and potassium (~1500-3000 or ~2000-2500 ppm by weight) can be advantageously recovered in the NF permeate stream.

[0025] Another benefit is a NF retentate stream containing very high levels of milk sugar, such as lactose, with reduced levels of other milk components, such as reduced protein content and / or reduced mineral content. The concentrated lactose stream can be used for pharmaceutical applications and production of lactose powder, as well as conversion to lactic acid, lactobionic acid or ethanol.

[0026] Furthermore, by performing reverse osmosis prior to nanofiltration, a large milk fraction (RO permeate) is formed that is substantially free of protein, milk sugar (lactose or its derivatives), fat, and minerals. Advantageously, this large RO permeate stream can be used throughout the manufacturing facility, such as in the diafiltration of a UF retentate or NF retentate. Additionally, the removal of large amounts of water makes the nanofiltration operation faster and more efficient.

[0027] According to one embodiment of the present invention, a method for preparing a dairy composition may comprise (or consist essentially of, or consist of) the following steps: (i) ultrafiltration of 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 step to produce a RO permeate fraction and a RO retentate fraction containing at least about 8 wt % lactose (lactose or its derivatives), (iii) nanofiltration of the RO retentate fraction to produce a NF permeate fraction containing about 300 to about 800 ppm sodium and about 1500 to about 3000 ppm potassium, and a NF permeate fraction containing at least about 10 wt % lactose (milk sugar) (lactose or its derivatives). In some embodiments, the step of combining may include combining at least the UF retentate fraction and the NF permeate fraction, while in other embodiments, the step of combining may include 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 the RO permeate and subjected to diafiltration.

[0028] In general, features of the method (e.g., characteristics of the dairy product, the ultrafiltration step and the resulting UF permeate fraction and UF retentate fraction, the nanofiltration step and the resulting NF permeate fraction and NF retentate fraction, the diafiltration step and the resulting DF / UF permeate fraction and DF / UF retentate fraction, the reverse osmosis step and the resulting RO permeate fraction and RO retentate fraction, and the components that are combined to form the dairy composition, etc.) are described independently herein, and these features can be combined in any combination to further describe the disclosed method. In addition, unless otherwise stated, other method steps can be performed before, during and / or after any step listed in the disclosed method. In addition, any dairy composition produced according to any disclosed method (e.g., a finished dairy product, ready for consumption) is within the scope of the present invention and is encompassed herein.

[0029] Filtration techniques (e.g., ultrafiltration, nanofiltration, diafiltration, etc.) can separate or concentrate components in a mixture (such as milk) by passing the mixture through a membrane system (or selective barrier) under suitable conditions (e.g., pressure). Thus, concentration / separation can be based on molecular size. The stream retained by the membrane is called the retentate (or concentrate). The stream that passes through the membrane pores is called the permeate. Referring now to the disclosed method for preparing 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 step to produce a RO permeate fraction and a RO retentate fraction containing at least about 8% by weight of milk sugar (lactose or a derivative thereof), (iii) nanofiltering the RO retentate fraction to produce a NF permeate fraction containing about 300 to about 800 ppm of sodium and about 1500 to about 3000 ppm of potassium, and a NF retentate fraction containing at least about 10% by weight of milk sugar (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 a dairy composition.

[0030] The dairy product in step (i) may comprise (or consist essentially of, or consist of) skimmed milk or, alternatively, whole milk. In some embodiments, the disclosed method may further comprise the step of separating (e.g., centrifuging or microfiltrating) raw or fresh milk (whole milk) into a dairy product (also referred to as skimmed milk) and a fat-rich fraction (also referred to as cream or butter fat). Raw or fresh milk (whole milk) may be cow's milk, which contains approximately 87% by weight of water, 3-4% by weight of protein, 4-5% by weight of carbohydrates / lactose, 3-4% by weight of fat, and 0.3-0.8% by weight of minerals. When fresh milk or a raw milk product is separated into a skim milk product and a fat-rich fraction, the fat-rich fraction generally contains high levels of fat (e.g., 20-50 wt. % fat or 30-50 wt. % fat) and solids (e.g., 30-60 wt. % or 40-55 wt. %), and generally contains approximately 1.5-4 wt. % protein, 2-5 wt. % lactose, and 0.2-0.9 wt. % minerals, but is not limited thereto.

[0031] In step (i), the ultrafiltration of the milk product can be carried out using an ultrafiltration membrane having a pore size generally in the range of 0.01 to 0.1 microns. In the dairy industry, ultrafiltration membranes are generally determined based on molecular weight cutoff (MWCO) rather than pore size. The molecular weight cutoff of the ultrafiltration membrane can vary between 1000-100,000 Daltons or 10,000-100,000 Daltons. For example, a polymer membrane system (or ceramic membrane system) can be used to ultrafilter the milk product. The polymer membrane system (or ceramic membrane system) can be configured to have such a pore size that a substance having a molecular weight greater than about 1,000 Daltons, greater than about 5,000 Daltons or greater than about 10,000 Daltons is retained while allowing substances of lower molecular weight to pass through. For example, a UF membrane system having a molecular weight cutoff of 10,000 Daltons can be used in the dairy industry for separating and concentrating 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 15-150 psig or 45-150 psig. Although not limited thereto, the ultrafiltration step can typically be performed at a temperature in the range of about 3 to about 15°C, such as about 4 to about 12°C or about 5 to about 10°C. Ultrafiltration at lower temperatures results in better product quality and organoleptic properties compared to higher temperature ultrafiltration (e.g., ~25-50°C), and in addition, if low temperature ultrafiltration is utilized, a pasteurization step is not required.

[0032] In step (ii), some or all of the UF permeate fraction may be subjected to a reverse osmosis step to produce an RO permeate fraction and an RO retentate fraction (the RO retentate fraction containing at least about 8% by weight of milk sugar (lactose or its derivatives). Reverse osmosis is a fine filtration process or concentration process in which substantially all of the remaining milk components are retained (RO retentate) and only water (RO permeate, milk) passes through. Typically, the molecular weight cutoff of the reverse osmosis membrane system is much less than 100 Da, and thus components other than water (e.g., minerals) are concentrated in the reverse osmosis process. Typically, reverse osmosis includes a membrane system having a pore size of less than or equal to about 0.001 μm. Operating pressures are typically in the range of 450-1500 psig or 450-600 psig. Temperatures in the range of about 5 to about 45° C. or about 15 to about 45° C. can typically be used.

[0033] In step (iii), some or all of the RO retentate fraction may be subjected to a nanofiltration step to produce a NF permeate fraction (containing about 300 to about 800 ppm of sodium and about 1500 to about 3000 ppm of potassium) and a NF retentate fraction (containing at least about 10% by weight of milk sugar (lactose or its derivatives). Nanofiltration in the dairy industry typically uses membrane elements that retain particles with a molecular weight above about 100-300 Da. Nanofiltration is a pressure-driven process in which a liquid is forced through a membrane under pressure and materials with a molecular weight greater than a specified cutoff are retained, while smaller particles pass through the membrane pores. For the separation of lactose from minerals, which is typically in the incoming stream, the pore size can be selected to maximize the retention of lactose. Like ultrafiltration, nanofiltration can perform both concentration and separation simultaneously.

[0034] Nanofiltration of the RO retentate fraction can be performed using a nanofiltration membrane having a pore size typically in the range of 0.001 to 0.01 microns, for example, a pore size in the range of about 0.001 to about 0.008 μm. In some embodiments, the nanofiltration step utilizes a membrane system having a pore size in the range of 0.001 to about 0.01 μm, wherein the operating pressure is typically in the range of 150-450 psig, and the operating temperature is in the range of about 10 to about 60° C. (or about 15 to about 45° C.), but is not limited thereto.

[0035] Optionally, the UF retentate fraction, some or all of the UF retentate fractions produced in step (i), can be subjected to a diafiltration step to produce a DF / UF permeate fraction and a DF / UF retentate fraction. The DF / UF permeate fraction can be mixed with the UF permeate and then subjected to reverse osmosis, and then the resulting RO retentate can be subjected to nanofiltration to extract minerals and separate lactose (milk sugar) (lactose or its derivatives). Typically, an ultrafiltration membrane is used to perform a diafiltration step, such as described above. However, other membranes can be used for the diafiltration step. In one embodiment, diafiltration of the UF retentate fraction can include diafiltration of a mixture of the UF retentate fraction and water. In another embodiment, diafiltration of the UF retentate fraction can include diafiltration of a mixture of the UF retentate fraction and the RO permeate fraction. In yet another embodiment, diafiltration of the UF retentate fraction can include diafiltration of a mixture of the UF retentate fraction, the RO permeate fraction, and water. These mixtures can utilize any suitable ratio or relative amounts of the UF retentate fraction and the RO permeate fraction and / or water. Typically, diafiltration of the UF retentate fraction yields a DF / UF permeate fraction (with milk sugar (e.g., lactose) and minerals extracted from the UF retentate) and a DF / UF retentate fraction (which is protein-rich).

[0036] When the UF retentate fraction is mixed with (diluted with) another component (e.g., water and / or RO permeate fraction) prior to introduction into the ultrafiltration membrane system, the weight ratio of the other component to the UF retentate fraction is typically in the range of about 0.1:1 to about 1:1, about 0.2:1 to about 0.8:1, or about 0.3:1 to about 0.7:1, but is not limited thereto. Diafiltration—using an ultrafiltration membrane—can be conducted at any suitable concentration factor, non-limiting examples of which include about 1.2 to about 5, about 1.3 to about 4, about 1.2 to about 3, or about 2 to about 3.

[0037] Step (iv) of the method for preparing a dairy composition comprises combining at least two of a UF retentate fraction, a DF / UF retentate fraction, a NF permeate fraction, a RO permeate fraction, a RO retentate fraction, and a fat-rich fraction to form a dairy composition. Any combination of these components may be mixed or combined in any suitable relative proportions to form a 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, a RO permeate fraction and / or water may also be 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, a RO permeate fraction and / or water may also be added in the combining step.

[0038] In addition, ingredients and / or additional milk fractions may also be added in the combining step. Additionally or alternatively, ingredients and / or additional milk components may be added to the dairy composition after the combining step. Non-limiting examples of suitable ingredients may include sugars / sweeteners, flavorings, preservatives (e.g., to prevent yeast or mold growth), stabilizers, emulsifiers, prebiotic substances, probiotics, vitamins, minerals, ω3 fatty acids, phytosterols, antioxidants or coloring agents, etc., and any mixtures or combinations thereof.

[0039] Other milk fractions can be "fractions rich in components", which means any fraction containing at least 15% more milk components (protein, lactose / sugar, fat, minerals) than those found in milk. For example, a lactose-rich fraction can contain about 6 to about 20% by weight of sugar (i.e., in any form, such as lactose, glucose, galactose, etc.), about 6 to about 18% by weight of sugar, or about 7 to about 16% by weight of sugar. A mineral-rich fraction can 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. A fat-rich fraction can 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.

[0040] These enriched milk fractions can be produced as described herein or by any technique known to those skilled in the art, such as by membrane filtration methods disclosed in U.S. Pat. Nos. 7,169,428, 9,510,606 and 9,538,770, which are incorporated herein by reference in their entirety. Additionally or alternatively, an enriched milk fraction (or multiple milk fractions) can be produced by a method comprising mixing water and powdered ingredients (e.g., protein powder, lactose powder, mineral powder, etc.).

[0041] Any suitable container and conditions can be used for any combination step disclosed herein, and these can be done in batches or continuously. For example, the components can be combined (optionally with stirring or mixing, and optionally with an ingredient (or ingredients) and / or an additional milk fraction (or multiple milk fractions)) in a suitable container (e.g., tank, silo, etc.) at atmospheric pressure to form a batch of finished dairy compositions. As another example, the components can be continuously combined in a pipeline or other suitable container at a micropressure (e.g., 5-50psig), optionally mixed with ingredients and / or additional milk fractions, and the finished dairy composition can be transferred to a storage tank or loaded into a container for retail distribution and sale. Representative systems that can be used for such continuous combination, mixing and / or packaging can include tetra aldose systems and tetra flexidose systems. Other suitable methods, systems and devices for combining components and other ingredients and / or milk fractions are apparent from the present invention.

[0042] If desired, lactase may be added to the milk product prior to ultrafiltration, or may be added to each component prior to the combining step, or may be added to the resulting milk composition. As described herein, the components may be combined in any suitable ratio, and optionally, any suitable ingredients and / or further milk fractions may be added in step (iv) to form the milk composition. Additionally or alternatively, any suitable ingredients and / or further milk components may be added to the milk composition after the combining step.

[0043] Consistent with embodiments of the present invention, if desired, the UF retentate fraction can be treated with lactase prior to the combining step. Likewise, if desired, the DF / UF retentate fraction can be treated with lactase prior to the combining step. Additionally or alternatively, lactase can be added during step (iv), or the milk composition can be treated with lactase after step (iv). In these cases, the lactose content can be reduced to less than about 1 wt%, less than about 0.5 wt%, less than about 0.2 wt%, or less than about 0.1 wt%.

[0044] Optionally, the method may also include a step of microfiltering a dairy product (e.g., skim milk) prior to the ultrafiltration step to obtain a MF permeate fraction and a MF retentate fraction. In such a case, step (i) may include ultrafiltering the MF permeate fraction to produce a UF permeate fraction and a UF retentate fraction. Microfiltration can be performed using a microfiltration membrane with a relatively large pore size, typically in the range of 0.1 to 10 microns, such as a pore size 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 with a pore size in the range of about 0.1 to about 0.2 μm, wherein the operating pressure is typically less than about 75 psig (e.g., 10-15 psig), and the operating temperature is in the range of about 5 to about 60°C (or about 35 to about 55°C), but is not limited thereto.

[0045] Typically, microfiltration membranes can be used in the dairy industry to remove bacteria, bacterial spores, somatic cells and other extraneous suspended matter from fluid milk, and thus improve the quality and shelf life of the resulting dairy products. Microfiltration membranes can be used to separate fat from cheese or cheese whey and to separate fat from fluid milk as an alternative to centrifugal separation.

[0046] The protein content of the UF retentate fraction and the DF / UF retentate fraction can independently be at least about 5 wt %, at least about 6 wt %, at least about 7 wt %, at least about 8 wt %, or at least about 9 wt % protein. Illustrative and non-limiting ranges of the protein content of the UF retentate and the DF / UF retentate can independently include about 5 to about 20 wt % protein, about 6 to about 18 wt % protein, or about 9 to about 15 wt % protein.

[0047] Similarly, although not limited thereto, the UF permeate fraction, the UF retentate fraction, the DF / UF permeate fraction, and the DF / UF retentate fraction may independently have a milk sugar (lactose or a derivative thereof) content of less than or equal to about 7 wt % or less than or equal to about 6 wt %, but greater than or equal to about 3 wt % or greater than or equal to about 3.5 wt %.

[0048] The lactose (milk sugar) (lactose or its derivatives) content of the NF retentate fraction can be at least about 8 wt%, at least about 10 wt%, at least about 14 wt%, at least about 17 wt%, or at least about 20 wt% lactose (milk sugar) (lactose or its derivatives), but is not limited thereto. Illustrative and non-limiting ranges of the lactose content of the NF retentate fraction can include about 10 to about 28 wt%, about 15 to about 28 wt%, about 15 to about 25 wt%, about 20 to about 28 wt%, or about 20 to about 25 wt% lactose (milk sugar) (e.g., lactose (lactose) or its derivatives). The solids content of the NF retentate fraction is typically at least about 15 wt%, at least about 20 wt%, or at least about 22 wt%, and can typically be in the range of up to 25-30 wt%. The NF retentate fraction contains minimal protein, typically less than about 1 wt%, less than about 0.7 wt%, less than about 0.5 wt%, or less than about 0.3 wt% protein. The NF retentate fraction typically contains about 0.8 to about 2 wt% minerals, such as about 1 to about 1.8 wt% minerals.

[0049] The NF permeate fraction typically contains less than 1% solids by weight, and only minimal amounts of milk sugar (e.g., lactose) and protein. Unexpectedly, the NF permeate contains significant amounts of minerals, typically in the range of about 0.35 to about 1% by weight, such as about 0.4 to about 0.8% by weight. In addition, 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.

[0050] After the reverse osmosis step, the RO retentate fraction contains a significant amount of milk sugar (lactose or its derivatives), such as at least about 8% by weight or at least about 10% by weight, and typically 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. Typically, the RO permeate (milk) fraction is substantially free of all milk components—fat, protein, milk sugar (e.g., lactose), and minerals. For example, the milk fraction may contain less than or equal to about 0.1% by weight of milk sugar (e.g., lactose), and less than or equal to about 0.1% by weight of minerals. In addition, the milk fraction may contain less than or equal to about 0.1% by weight of fat, and less than or equal to about 0.1% 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.

[0051] Illustrative and non-limiting examples of suitable separation methods 10 consistent with embodiments of the methods of the present invention are described in Figure 1 . First, whole milk (raw milk) 15 is separated 20 into cream 28 and skimmed milk product 22. Skimmed milk product 22 is then subjected to ultrafiltration 30, such as via a polymer membrane system, as described herein, to obtain a UF retentate 38 (commonly referred to as a protein-rich milk fraction) and a UF permeate 32 (which contains lactose (milk sugar) (lactose or its derivatives) and minerals). The UF permeate 32 is then subjected to reverse osmosis 40 to obtain a RO retentate 48 containing milk sugar (e.g., lactose (lactose) or its derivatives) and minerals and a RO permeate 42 consisting essentially of water. The RO retentate 48 is then subjected to nanofiltration 50 to obtain a NF permeate 52 (which is rich in minerals) and a NF retentate 58 (which is rich in lactose). Optionally, in Figure 1 In the process, some or all of the UF retentate 38 is mixed with the RO permeate 42 and subjected to diafiltration 60 to obtain a DF / UF permeate fraction 62 and a DF / UF retentate fraction 68 (which is protein-rich).

[0052] exist Figure 1In the embodiment of the present invention, a dairy composition 80 is formed by combining or mixing the UF retentate fraction 38, the DF / UF retentate fraction 68, the NF permeate fraction 52, the RO permeate fraction 42, and the cream 28 (fat-rich fraction) in any suitable proportions. As desired, the components may be treated with lactase 72, 74, 76 prior to mixing the components or after forming the dairy composition 80. Subsequently, the dairy composition 80 is heat treated 85, then cooled and packaged 90.

[0053] Consistent with the embodiments of the improved methods for preparing dairy compositions disclosed herein, if desired, these methods may further comprise the step of treating the respective dairy compositions with lactase. Thus, the lactose content may be reduced to less than about 1 wt%, less than about 0.5 wt%, less than about 0.2 wt%, or less than about 0.1 wt%.

[0054] In addition, these methods may further include the step of heat treating the dairy composition. In one embodiment, the heat treatment step may include pasteurizing at a temperature in the range of about 80°C to about 95°C for a period of time in the range of about 2 to about 15 minutes. In another embodiment, the heat treatment step may include UHT sterilization at a temperature in the range of about 135°C to about 145°C for a period of time in the range of about 1 to about 10 seconds. In yet another embodiment, the heat treatment step may include ultra-UHT sterilization at a temperature in the range of about 148°C to about 165°C for a period of time in the range of about 0.05 to about 1 second (e.g., 155°C for about 0.1 second). Other suitable pasteurization or sterilization temperature and time conditions are apparent from the present invention. In addition, the present invention is not limited by the method or equipment used to perform the pasteurization / sterilization process - any suitable technology and apparatus may be used, whether batch operation or continuous operation.

[0055] In some embodiments of the present invention, after the heat treatment step, the improved method for preparing the dairy composition can also include the step of packaging the dairy composition in any suitable container and under any suitable conditions (aseptically or otherwise). Therefore, after the various components, ingredients and other milk fractions described herein are combined to form the dairy composition, the dairy composition can be packaged in a container under aseptic conditions (or non-aseptic conditions). Any suitable container can be used, such as a container that can be used to distribute and / or sell dairy products in retail channels. Illustrative and non-limiting examples of typical containers include cups, bottles, bags (bags) or pouches (pouches) etc. The container can be made of any suitable material, such as glass, metal, plastics etc., and combinations thereof.

[0056] Although not limited thereto, 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 less than or equal to about 4 % by weight.

[0057] Representative and non-limiting examples of dairy compositions consistent with the present invention may contain less than or equal to about 0.5% by weight fat, about 2 to about 15% by weight protein, about 0.5 to about 2% by weight minerals, and less than or equal to about 4% by weight lactose. Another representative and non-limiting example of a dairy composition consistent with the present invention may contain about 0.5 to about 1.5% by weight fat, about 2 to about 15% by weight protein, about 0.5 to about 2% by weight minerals, and less than or equal to about 4% by weight lactose. In addition, another representative and non-limiting example of a dairy composition consistent with the present invention may contain about 1.5 to about 2.5% by weight fat, about 2 to about 15% by weight protein, about 0.5 to about 2% by weight minerals, and less than or equal to about 4% by weight lactose. In addition, another representative and non-limiting example of a dairy composition consistent with the present invention may contain about 2.5 to about 5% by weight fat, about 2 to about 15% by weight protein, about 0.5 to about 2% by weight minerals, and less than or equal to about 4% by weight lactose.

[0058] Additional non-limiting examples of typical milk compositions that can 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, high calcium, and reduced sugar milk, etc. Example

[0059] The present invention is further illustrated by the following examples, which are not interpreted in any way as limiting the scope of the present invention. After reading the description herein, various other aspects, embodiments, modifications and equivalents thereof may be contemplated by those of ordinary skill in the art without departing from the spirit of the present invention or the scope of the appended claims.

[0060] Total solids (wt %) are determined according to procedure SMEDP 15.10C of a CEM Turbo solids and moisture analyzer (CEM Corporation, Matthews, North Carolina). Ash is the residue remaining after combustion to constant weight at 550°C in a suitable apparatus; this treatment at 550°C generally removes all organic matter, and the remaining material is mainly mineral (Standard Methods for the examination of dairy products, 17th edition (2004), American Public Health Association, Washington, DC). Ash testing is performed by using a Phoenix (CEM microwave oven), which heats the sample at 550°C for 30 minutes. Ash content (or mineral content) is determined in wt %.

[0061] The specific Ca, Mg, Na and K contents were determined using a Perkin Elmer atomic absorption spectrophotometer. The samples were treated with trichloroacetic acid to precipitate the protein and the filtrate was analyzed by an atomic absorption spectrophotometer. The protein content, fat content and lactose content were determined by the AOAC (Association of Official Analytical Chemists) method.

[0062] according to Figure 1In Example 1, raw milk (below 5°C) is separated into a fat-rich fraction (cream) and a fat-free fraction (fat-free milk or skim milk) by a centrifugal separator. The centrifugation process is carried out at a temperature below 5°C. The skim milk at 5°C is then fractionated into a protein-rich fraction (UF retentate) and a lactose-rich fraction (UF permeate) by passing the skim milk through a UF membrane having a pore size where any molecule with a molecular weight greater than 10,000 Daltons (Da) is retained in the UF retentate, which has an average protein content of 11.9 wt% and a fat content of 0.4 wt%. The UF permeate has a total solids content of 5.62-5.77 wt%, a protein content of 0.10-0.15 wt%, an ash content of 0.46-1.15 wt%, 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 RO spiral wound polymer elements (Koch membrane, 0.95 m long and 0.095 m diameter). The temperature during the RO treatment varied from 6 to 19° C. at a pressure of 400-500 psig. The RO concentrate (RO retentate) was then demineralized in a NF system (GEA Model R Pilot Unit, GEA Process Engineering Inc.) using NF membrane elements (NF-200, spiral wound membrane elements, molecular weight cutoff 200 Da, diameter 3”, length 0.95 m; diameter 0.095 m) at a temperature in the range of 12 to 26° C.

[0063] Table 1 summarizes the corresponding average compositions of the UF permeate fraction, UF retentate fraction, RO permeate fraction, RO retentate fraction, NF retentate fraction and NF permeate fraction during the 8-hour experiment of Example 1. In Table 1, the mineral content (in wt%) is generally similar to the ash content (in wt%), and therefore the results of the ash test are used to quantify the total mineral content in the present invention. For each milk fraction, Table 1 summarizes the corresponding average Ca, Mg, Na and K contents (in ppm by weight).

[0064] The dairy compositions were prepared by mixing UF retentate, NF permeate, RO concentrate, RO permeate and cream. Commercial lactase was added to the dairy compositions to convert lactose to glucose and galactose at 4°C for 16 hours prior to heat treatment. Table II summarizes the dairy compositions prepared using the milk fractions from Example 1 and the comparative milk fractions (prepared using UF, then NF, then RO). The goal was to obtain substantially identical dairy compositions, so slightly different blends were used for the comparative example and Example 1. A six-person panel informally evaluated the sensory properties of the samples using a triangular discrimination test (i.e., the panelists were provided with one different sample and two similar samples, and were instructed to taste the samples and identify the odd one). The panel was unable to distinguish any differences between the composition of Example 1 and the comparative composition.

[0065] Table III summarizes the construction example 2, which is a simulation experiment using UF / RO / NF, and Table IV summarizes the simulation comparison experiment using conventional UF / NF / RO. These simulations were performed to provide a direct comparison of UF / RO / NF and UF / NF / RO processes, and to demonstrate the benefits of the UF / RO / NF process of Example 2, in which reverse osmosis is performed before the final nanofiltration step. Unexpectedly and advantageously, the UF / RO / NF process of Example 2 can recover more water (for use in other parts of the production facility without the need to purchase water), recover more minerals, and provide a more concentrated lactose stream compared to the conventional UF / NF / RO process.

[0066] Table I. Summary of Example 1

[0067]

[0068]

[0069] NF Permeate NF Retentate UF Retentate Total Solids weight% 0.75 25.6 19.2 protein weight% - - 11.9 lactose weight% 0.2 24 5.6 Minerals weight% 0.51 1.4 1.3 Ca ppm 72 735 - Mg ppm 7 163 - Na ppm 566 945 - K ppm 2194 3556 -

[0070] Table II. Summary of milk compositions

[0071]

[0072] Table III. Summary of Example 2 Process - UF, RO and NF

[0073]

[0074]

[0075] Percentage of water recovered from 100 kg skim milk = 36.8 wt% (33.5 / 0.91)

[0076] Percentage of minerals recovered in NF permeate = 20.1 wt% (0.145 / 0.72)

[0077] Lactose percentage in lactose concentrate = 19.2 wt%

[0078] Table IV. Summary of the compared methods - UF, NF and RO

[0079]

[0080] Percentage of water recovered from 100 kg skim milk = 24.5% (22.33 / 0.91)

[0081] Percentage of minerals recovered in RO retentate = 15.5 wt% (0.112 / 0.72)

[0082] Lactose percentage in lactose concentrate = 14.4 wt%

Claims

1. A method for preparing a milk composition, the method comprising: (i) ultrafiltering the milk 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 step to produce a RO permeate fraction and a RO retentate fraction comprising at least 8 wt.% lactose; (iii) nanofiltration of the RO retentate fraction to produce a NF permeate fraction containing 300 to 800 ppm sodium and 1500 to 3000 ppm potassium, and a NF retentate fraction comprising at least 10 wt % lactose; 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 a fat-rich fraction to form the dairy composition.

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

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

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

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

6. The method of claim 1, wherein the mineral content of the NF permeate fraction is 0.35 to 1 wt% or 0.4 to 0.8 wt%.

7. The method of claim 1, wherein the potassium content of the NF permeate fraction is 2000 to 2500 ppm.

8. The method of claim 1, wherein the sodium content of the NF permeate fraction is 400 to 700 ppm.

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

10. The method of claim 1, wherein the lactose content of the UF permeate fraction and / or the UF retentate fraction is 3.5 to 6 wt%.

11. The method of claim 1, wherein the lactose content of the DF / UF permeate fraction and / or the DF / UF retentate fraction is 3.5 to 6 wt%.

12. The method of claim 1, wherein the milk product is ultrafiltered at a temperature of 4 to 12°C or 5 to 10°C.

13. The method of claim 1, wherein the combining step comprises: (a) combining the UF retentate fraction and the NF permeate fraction, or (b) combining the fat-rich fraction, the UF retentate fraction and the NF permeate fraction.

14. The method of claim 1, further comprising the step of diafiltering the UF retentate fraction to produce a DF / UF permeate fraction and the DF / UF retentate fraction.

15. The method of claim 14, wherein diafiltering the UF retentate fraction comprises diafiltering a mixture of the UF retentate fraction, the RO permeate fraction, and optionally water.

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

17. The method of claim 1, wherein the method further comprises the step of separating raw milk into the milk product and the fat-rich fraction.

18. The method of claim 1, wherein the combining step further comprises adding water to form the milk composition.

19. The method of claim 1, wherein the milk product comprises skim milk or whole milk.

20. The method of claim 1, wherein the UF retentate fraction is treated with lactase prior to the combining step, or the DF / UF retentate fraction is treated with lactase prior to the combining step, or the method further comprises the step of treating the dairy composition with lactase, or any combination thereof.

21. The method of claim 1, wherein the method further comprises the step of microfiltering the milk product prior to step (i).

22. The method of claim 1, wherein the dairy composition has a fat content of 0.05 to 10 wt% or 0.1 to 5 wt%.

23. The method of claim 1, wherein the dairy composition has a protein content of 1 to 15 wt% or 3 to 10 wt%.

24. The method of claim 1, wherein the dairy composition has a mineral content of 0.5 to 2 wt%.

25. The method of claim 1, wherein the dairy composition has a lactose content of less than or equal to 4% by weight.

26. The method according to claim 1, 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, reduced-sugar milk.

27. The method of claim 1, wherein the combining step further comprises adding ingredients, wherein the ingredients comprise sugars / sweeteners, flavorings, preservatives, stabilizers, emulsifiers, prebiotic substances, probiotics, vitamins, minerals, omega 3 fatty acids, phytosterols, antioxidants, colorants, or any combination thereof.

28. The method of claim 1, wherein the method further comprises the step of heat treating the dairy composition.

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 period in the range of 1 to 10 seconds.

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

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

32. The method according to claim 1, further comprising the steps of: The dairy composition is packaged in a container.

33. The method of claim 1, wherein the amount of water recovered from the milk product is greater than the amount of water obtained by an otherwise identical process wherein nanofiltration is performed prior to reverse osmosis.

34. The method of claim 1, wherein the amount of minerals in the NF permeate fraction is greater than the amount of minerals in a RO retentate fraction obtained by an otherwise identical process wherein nanofiltration is performed prior to reverse osmosis.

35. The method of claim 1, wherein the concentration of lactose in the NF retentate fraction is greater than the concentration of lactose in a NF retentate fraction obtained by an otherwise identical process wherein nanofiltration is performed prior to reverse osmosis.

36. A dairy composition prepared by the method according to any one of claims 1 to 35.

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