Methods and system for purifying a liquid comprising inulin

Abstract

The present invention relates to a method and system for purifying inulin, comprising ion exchange and nanofiltration. Optionally, reverse osmosis can be implemented in order to allow ion exchange regeneration and dilution of nanofiltered inulin.

Description

[0001] METHODS AND SYSTEM FOR PURIFYING A LIQUID COMPRISING INULIN

[0002] FIELD OF THE INVENTION

[0003] The innovation pertains to a method and system for purifying a liquid comprising inulin, specifically sourced from chicory roots. Additionally, the invention encompasses an inulin composition obtained through this method. Furthermore, the invention concerns food products containing such an inulin composition and specific applications thereof.

[0004] BACKGROUND OF THE INVENTION

[0005] Dietary fibers are carbohydrates that resist digestion and absorption in the human small intestine. Derived from food materials through physical, enzymatic, or chemical processes, they offer various beneficial physiological effects. Typically, dietary fibers pass through much of the digestive system without being broken down and can undergo partial or complete fermentation by the intestinal microbiota.

[0006] Inulins are naturally occurring polysaccharides with versatile applications, serving as prebiotics, low-calorie dietary fibers in food products, providing health benefits and improving texture and shelf-life. They are also used in medical applications and human and animal feed formulations. Structurally, inulins are composed of linear chains of fructose units, often with a terminal glucose unit. The linkage position of the fructose residues determines the type of the fructan. Linkage normally occurs at one of the two primary hydroxyls (OH-1 or OH-6), for inulin the fructosyl residues are linked by p-2,l-linkages.

[0007] Extracted primarily from plant sources like chicory root, inulins undergo industrial-scale purification involving hot water extraction of sliced plant material, followed by purification of the extract and isolation of inulin. Purification methods typically include removal of impurities and obtaining an inulin-rich composition. Although these purification methods are effective for purifying liquids with inulin, they come with certain drawbacks. Firstly, these purification methods typically only partially remove impurities from the liquid, leading to incomplete purification and potential presence of unwanted residual impurities in the final product, thus impacting its quality. Ion exchangers typically can introduce ions, such as in particular Cl’, but downstream equipment as a consequence can suffer from corrosion. Further, the use of ion exchangers requires regeneration process of ion exchange resins, which typically involves the use of chemical solutions to remove adsorbed ions from the resin. These chemical solutions, often strong acids or bases, can generate chemical waste that needs to be treated or disposed of properly. The disposal of such chemical waste can pose environmental risks if not managed carefully. Additionally, the production of these chemical solutions may involve energy-intensive processes and the use of raw materials that contribute to environmental pollution and resource depletion.

[0008] In view thereof, there remains a need in the art for further and / or improved methods for the purification of inulin and for sustainable manufacturing of it.

[0009] SUMMARY OF THE INVENTION

[0010] The present inventors have designed a method and a system for purifying a liquid comprising inulin, thereby addressing one or more of the above-mentioned problems in the art.

[0011] Accordingly, a first aspect of the invention relates to a method for purifying a liquid comprising inulin, the method comprising the steps of:

[0012] (a) providing a liquid comprising inulin, and anions (optionally also including (conjugate bases of) organic acids such as malate, citrate, oxalate, and / or lactate), such as monovalent, bivalent and / or multivalent anions and cations, such as monovalent, bivalent and / or multivalent cations, and / or a combination thereof;

[0013] (b) subjecting the liquid to one or more ion-exchange treatment with one or more ion exchanger, wherein anions in said liquid are exchanged for one or more anion and cations are exchanged for one or more cation;

[0014] (c) subjecting the treated liquid to at least one nanofiltration treatment, to obtain a nanofiltration retentate fraction comprising purified inulin and a nanofiltration permeate fraction.The invention further relates to a system for performing the method of the invention.

[0015] The inventors have surprisingly found that the present method and system facilitates the removal of ions and impurities from the liquid comprising inulin by coupling ion exchange to nanofiltrations, whilst preserving the amount of inulin and minimizing the risk of inulin fractionation. This environmentally friendly approach ensures high inulin yields, qualifying it as a viable industrial-scale purification method for liquids comprising inulin, while at the same time minimizing water and chemicals usage as well as minimizing waste.

[0016] Moreover, corrosion, in particular in downstream equipment, such as resulting from Cl’ ions, is minimized when operating the method and system according to the invention.

[0017] Further, the present invention offers a sustainable solution by subjecting the nanofiltration permeate fraction to reverse osmosis treatments. This yields a reverse osmosis retentate fraction containing mainly monovalent anions and cations, while the reverse osmosis permeate fraction contains purified water with reduced levels of these ions. By incorporating at least a portion of the reverse osmosis retentate fraction into ion exchange processes for regenerating the ion exchanger and / or utilizing a portion of the reverse osmosis permeate fraction in nanofiltration treatment, significant reductions in costs, water usage, and required chemicals for purifying liquids comprising inulin are achieved.

[0018] Hence, the present method advantageously allows to prepare inulin products in an efficient and sustainable way.

[0019] In essence, the invention provides for the following aspects:

[0020] Aspect 1. A method for purifying a liquid comprising inulin comprising the steps of:

[0021] (a) providing a liquid comprising: inulin, anions and cations;

[0022] (b) subjecting the liquid of a) to one or more ion-exchange treatment(s) with one or more ion exchanger(s), wherein the anions in said liquid are exchanged for a single monovalent anion and wherein the cations in said liquid are exchanged for a single monovalent cation;

[0023] (c) subjecting the treated liquid of b) to at least one nanofiltration treatment, preferably comprising at least one diafiltration step and optionally comprising at least one concentration step, to obtain a nanofiltration retentate fraction comprising purified inulin and a nanofiltration permeate fraction.

[0024] Aspect 2. The method according to aspect 1, wherein said nanofiltration permeate fraction is subjected to one or more water purification process(es).

[0025] Aspect 3. The method according to aspect 2, wherein the water purification process is a reverse osmosis treatment to obtain a reverse osmosis retentate fraction and a reverse osmosis permeate fraction.

[0026] Aspect 4. The method according to aspect 3, wherein at least part of the reverse osmosis retentate fraction is used to regenerate the one or more ion exchanger.

[0027] Aspect 5. The method according to any one of aspects 3 or 4, wherein at least part of the reverse osmosis permeate fraction is used during the nanofiltration treatment.

[0028] Aspect 6. The method according to aspects 5, wherein the nanofiltration treatment comprises one diafiltration step in which at least part of the reverse osmosis permeate fraction is used.

[0029] Aspect ?. The method according to any one of aspects 1 to 6, wherein the nanofiltration treatment comprises at least two subsequent diafiltration steps.

[0030] Aspect 8. The method according to any one of aspects 1 to 7, wherein in the nanofiltration treatment, a transmembrane pressure of at least 10 bars is applied. Aspect 9. The method according to any one of aspects 1 to 8, wherein the nanofiltration treatment is performed at a pH between 3 and 9.

[0031] Aspect 10. The method according to any one of aspects 1 to 9, wherein the ion-exchanger comprises an anion exchange resin and cation exchange resin containing respectively the single species of monovalent cation and the single species of monovalent anion to generate a treated liquid comprising the single species of monovalent cations and the single species of monovalent anion.

[0032] Aspect 11. The method according to any one of aspects 1 to 10, wherein after the nanofiltration treatment the nanofiltration permeate fraction is subjected to a demineralisation step to remove the single species of monovalent cation and the single species of monovalent anions.

[0033] Aspect 12. The method according to any one of aspects 1 to 10, wherein the single species of monovalent cation comprise sodium and / or potassium ions and the single species of monovalent anions comprise chloride ions.

[0034] Aspect 13. The method according to any one of aspects 1 to 12, wherein prior to step c) and after step b) the liquid is heated to about 110 degrees Celsius and subsequently cooled to at most about 65 degrees Celsius prior to nanofiltration.

[0035] Aspect 14. The method according to any one of aspects 1 to 13, wherein at least 50 % of the ionic load (expressed in milliequivalent (mEq) / (kg dry matter)) of the liquid after ion exchange treatment is in the form of monovalent anions and monovalent cations, preferably sodium and / or potassium ions and chloride ions.

[0036] Aspect 15. A system for purifying a liquid comprising inulin with a method according to any one of claims 1 to 14, wherein the system comprises an ion-exchanger for exchanging anions and cations in the liquid comprising inulin for monovalent cations and anions, the ion-exchanger being connected to a nanofiltration apparatus for filtering the liquid comprising inulin, monovalent cations and anions.

[0037] Aspect 16. The system according to aspect 15, further comprising a reverse osmosis means which is connected to the nanofiltration means and / or connected to the ion-exchanger, preferably a reverse osmosis means which is connected to the nanofiltration means and connected to the ion-exchanger. The above and further aspects and preferred embodiments of the invention are described in the following sections and in the appended claims. The subject-matter of appended claims is hereby specifically incorporated in this specification.

[0038] DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 composition of the liquid comprising inulin in relation to the cycles of the ion exchange treatment with anion exchange and cation exchange according to an embodiment of the invention. Figure 2 ionic load as a function of the degree of diafiltration and treated liquid according to an embodiment of the invention.

[0040] Figure 3 reduction in the levels of glucose and fructose in function of the degree of diafiltration according to an embodiment of the invention.

[0041] Figure 4 ionic load (in mEq / kg dry matter) of the nanofiltration retentate fraction, comparing results with ("treated liquid") and without ("untreated liquid") prior ion exchange treatment according to an embodiment of the invention.

[0042] Figure 5 mass rate reduction of glucose, fructose (A) and protein (B) in function of diafiltration according to an embodiment of the invention.

[0043] Figure 6 concentration of proteins, sugars, organic acids, monovalent and divalent ions in the reverse osmosis permeate, deioinised water and the untreated liquid according to an embodiment of the invention.

[0044] Figure 7 composition of the reverse osmosis retentate fraction after the reverse osmosis treatment according to an embodiment of the invention.

[0045] Figure 8 inulin purification method and system according to an embodiment of the invention.

[0046] DETAILED DESCRIPTION OF THE INVENTION

[0047] As used herein, the singular forms "a", "an", and "the" include both singular and plural referents unless the context clearly dictates otherwise.

[0048] The terms "comprising", "comprises" and "comprised of" as used herein are synonymous with "including", "includes" or "containing", "contains", and are inclusive or open-ended and do not exclude additional, non-recited members, elements or method steps. The terms also encompass "consisting of" and "consisting essentially of".

[0049] The recitation of numerical ranges by endpoints includes all numbers and fractions subsumed within the respective ranges, as well as the recited endpoints. The term "about" as used herein when referring to a measurable value such as a parameter, an amount, a temporal duration, and the like, is meant to encompass variations of and from the specified value, in particular variations of + / -10% or less, preferably + / -5% or less, more preferably + / -1% or less, and still more preferably + / -0.1% or less of and from the specified value, insofar such variations are appropriate to perform in the disclosed invention. It is to be understood that the value to which the modifier "about" refers is itself also specifically, and preferably, disclosed.

[0050] Whereas the term "one or more", such as one or more members of a group of members, is clear per se, by means of further exemplification, the term encompasses inter alia a reference to any one of said members, or to any two or more of said members, such as, e.g., any33,34,35,36 or37 etc. of said members, and up to all said members.

[0051] All documents cited in the present specification are hereby incorporated by reference in their entirety.

[0052] Unless otherwise specified, all terms used in disclosing the invention, including technical and scientific terms, have the meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. By means of further guidance, term definitions may be included to better appreciate the teaching of the present invention.

[0053] The inventors achieved enhanced purification of inulin by integrating ion exchange, replacing ions in the inulin-containing liquid with a single species of monovalent ions while preserving its ionic load, with nanofiltration enhances the removal efficiency of these monovalent ions, resulting in a purer form of inulin.

[0054] A first aspect of the invention relates to a method for purifying a liquid comprising inulin, the method comprising the steps of:

[0055] (a) providing a liquid comprising inulin, and anions, such as monovalent, bivalent and / or multivalent anions and cations, such as monovalent, bivalent and / or multivalent cations, and / or a combination thereof;

[0056] (b) subjecting the liquid to one or more ion-exchange treatment with one or more ion exchanger, wherein anions in said liquid are exchanged for one or more, preferably a single, monovalent anion, such as chloride ions (Cl ) and cations are exchanged for one or more, preferably a single, monovalent cation, such as sodium ions (Na+);

[0057] (c) subjecting the treated liquid to at least one nanofiltration treatment to obtain a nanofiltration retentate fraction comprising purified inulin and a nanofiltration permeate fraction. In certain embodiments, the nanofiltration treatment comprises at least one diafiltration step. In certain embodiments, the nanofiltration treatment comprises at least one concentration step. In certain embodiments, the nanofiltration treatment comprises at least one diafiltration step and optionally at least one concentration step. In a preferred embodiment the nanofiltration treatment comprises at least one concentration step and at least one diafiltration step.

[0058] As used herein, the term "anions" typically refers to negatively charged ions, typically formed by the gain of one or more electrons by an atom or a group of atoms. Typically, an anion contains more electrons than protons. Whereas, the term "cations", as used herein, generally refers to positively charged ions, formed by the loss of one or more electrons from an atom or a group of atoms. Anions and / or cations as used herein may include organic acids and their conjugate bases, such as for instance malate, citrate, lactate, and / or oxalate. The term "monovalent" ions generally refers to atoms or groups of atoms that have gained or lost one electron, and therefore exhibit a single positive or negative charge. In embodiments, monovalent cations typically refer to positively charged atoms, radicals, or groups of atoms with a valence of +1. Preferably the monovalent cations and the monovalent anions are salt-forming monovalent cations and salt-forming monovalent anions. Examples of monovalent cations include, but are not limited to, sodium ion (Na+), potassium ion (K+). On the other hand, monovalent anions typically refer to negatively charged atoms, radicals, or groups of atoms with a valence of -1. Examples of monovalent anions include, but are not limited to, chloride ion (Cl“) and nitrate ion (NO3). The term "bivalent" or "divalent" ions are generally formed by gaining or losing two valence electrons. In embodiments, divalent cations typically refer to positively charged atoms, radicals, or groups of atoms with a valence of +2. Examples of divalent cations include, but are not limited to, calcium (Ca2+), magnesium (Mg2+), zinc (Zn2+), and iron (II) (Fe2+). In embodiments, divalent anions typically refer to negatively charged atoms, radicals, or groups of atoms with a valence of -2. Divalent anions are typically formed by gaining two valence electrons and attaining a negative charge. Examples of divalent anions include, but are not limited to, sulfate ion (SO42-), carbonate ion (CO32-), sulfite ion (SO32-), and silicate ion (SiO32-). The term "trivalent" ions are generally formed by gaining or losing three valence electrons. In embodiments, trivalent anions typically refer to negatively charged atoms, radicals, or groups of atoms with a valence of -3. trivalent anions are typically formed by gaining three valence electrons and attaining a negative charge. Examples of trivalent anions include, but are not limited, to phosphate ion (PO43-

[0059] In embodiments, the single species of monovalent cation and the single species of monovalent anion are selected such that, together, they form a recoverable salt. A recoverable salt in the context of the present invention is understood as a salt that remains present in the treated liquid after ion exchange and nanofiltration, and that can be concentrated, separated and / or recycled in downstream processing, for example, but without limitation, in a reverse osmosis step or in an ion exchange step. Preferred recoverable salts are stable, non-volatile and compatible with regeneration of ion exchange resins as well as with reuse as process water.

[0060] Examples include sodium chloride (NaCI), potassium chloride (KCI), sodium hydroxide (NaOH), potassium hydroxide (KOH), sodium lactate, potassium lactate, sodium citrate, potassium citrate, sodium malate, potassium malate, sodium oxalate, potassium oxalate, and analogous salts of other monovalent anions such as carbonate, sulfate, sulfite, phosphate and silicate, provided they are present in monovalent form and yield a recoverable salt stream.

[0061] By contrast, transient ionic pairs such as H+ / OH“, which recombine to water and therefore do not provide a recoverable salt stream, are excluded. The deliberate selection of recoverable salts allows efficient recycling of the reverse osmosis retentate to regenerate the ion exchangers and of the reverse osmosis permeate as diafiltration water, thereby minimizing chemical consumption, corrosion, and effluent.

[0062] As used herein, the term "organic acids" has its usual meaning known in the art. By means of example, organic acids as used herein can be one or more of lactic acid, citric acid, malic acid, or oxalic acid. As used herein, the term "conjugate base of organic acids" has its usual meaning known in the art. By means of example, conjugate bases of organic acids as used herein can be one or more of lactate, citrate, malate, or oxalate. Organic acids as referred to herein typically refer to organic acids or conjugate bases thereof naturally present in inulin comprising compositions, such as originating from or obtained from chicory (or another plant source from which inulin is extracted), i.e. organic acids or conjugate bases thereof naturally present in chicory (or another plant source from which inulin is extracted).

[0063] The methods as taught herein are preferably performed on an industrial scale. The term "industrial scale" as used herein refers to a method which is carried out in an installation that can process at least 0.5 ton of raw material per day (24 hours). For instance, in an industrial method as taught herein at least 0.5 ton raw material (e.g., liquid comprising inulin) is processed per day, such as at least 1 ton raw material (e.g., liquid comprising inulin), at least 5 ton raw material, at least 50 ton raw material, at least 100 ton raw material, or more such as at least 1000 ton or at least 3000 ton raw material is processed per day.

[0064] The methods as taught herein, e.g. as in any one of the aspects 1 to 14 stated above comprise in step (b), subjecting the liquid to one or more ion-exchange treatment with one or more ion exchanger, wherein anions, preferably including organic acids and / or their conjugate bases, in particular lactate, citrate, malate, and / or oxalate, in said liquid are exchanged for a monovalent anion and cations are exchanged for a monovalent cation.

[0065] In embodiments of the methods as taught herein, e.g. as in any one of the aspects 1 to 14 stated above, at least 50 %, at least 51%, at least 52%, at least 53%, at least 54%, at least 55%, at least 56%, at least 57%, at least 58%, at least 59%, at least 60%, at least 61%, at least 62%, at least 63%, at least 64%, at least 65%, at least 66%, at least 67%, at least 68%, at least 69%, at least 70%, at least 71%, at least 72%, at least 73%, at least 74%, at least 75%, at least 76%, at least 77%, at least 80% of the ionic load (in milliequivalent (mEq) / (kg dry matter)) of the liquid after said ion exchange treatment is in the form of monovalent anions and monovalent cations, preferably sodium and / or potassium ions and chloride ions.

[0066] In embodiments of the methods as taught herein, e.g. as in any one of the aspects 1 to 14 stated above, up to substantially 100%, up to 99% up to 98%, up to 97%, up to 96%, up to 95%, up to 94%, up to 93%, up to 92%, up to 91%, up to 90%, up to 89%, up to 88%, up to 87%, up to 86%, up to 85%, up to 84%, up to 83%, up to 82%, up to 81%, up to 80% of the ionic load (in milliequivalent (mEq) / (kg dry matter)) of the liquid after ion exchange treatment is in the form of monovalent anions and monovalent cations, preferably sodium and / or potassium ions and chloride ions.

[0067] In embodiments of the methods as taught herein, e.g. as in any one of the aspects 1 to 14 stated above, an ion-exchange treatment can exchange between 50 percent (%) and substantially 100%, 60% and 90%, between 65% and 89%, between 70% and 88%, between 75% and 87%, between 80% and 86%, between 81% and 86% of the ionic load (in milliequivalent (mEq) / (kg dry matter)) of the liquid after exchange are in the form of monovalent anions and monovalent cations, preferably for sodium and / or potassium ions and chloride ions.

[0068] As used herein, the term "ionic load" refers to the total concentration of ions present in a liquid. The ionic load can be quantified as the cumulative effect of all charged particles (cations and anions) in the liquid, taking into account both their individual concentrations and valence (charge).

[0069] Mathematically, the ionic load can be represented as:

[0070] Where:

[0071] • N is the total amount of ion species

[0072] Zj is the absolute value of the valence of the i-th ion Q is the concentration of the i-th ion (in millimoles per kilogram of dry matter).

[0073] In embodiments of the methods as taught herein, e.g. as in any one of the aspects 1 to 14 stated above, the one or more ion-exchange treatment comprises at least one anion exchange step and at least one cation exchange step to generate a treated liquid comprising inulin, the single species of monovalent cations and the single species of monovalent anions. In certain embodiments, the one or more ion-exchange treatment comprises an anion exchange step and cation exchange step to generate a treated liquid comprising inulin, sodium and / or potassium ions and chloride ions. In embodiments, the ion-exchanger comprises an anion exchange resin and / or cation exchange resin to generate a treated liquid comprising inulin, the single species of monovalent cations and the single species of monovalent anions. In certain embodiment, the ion-exchanger comprises an anion exchange resin and cation exchange resin to generate a treated liquid comprising inulin, sodium and / or potassium ions and chloride ions. In certain embodiments, the ion-exchanger comprises a mixed-bed resin to generate a treated liquid comprising inulin, sodium and / or potassium ions and chloride ions. Such mixed-bed resin typically contains cation exchange sites and anion exchange sites within the same resin beads.

[0074] As used herein, the term "anion exchange" generally refers to ion exchange wherein anion exchange resins are employed. These resins contain positively charged functional groups that selectively exchange anions, such as chloride ions (Cl ), for among others sulfate ions, phosphate ions, and organic acids or conjugate bases thereof such as oxalate ions, malate ions, lactate ions, and citrate ions in the liquid comprising inulin (i.e. these anions are replaced by for instance Cl ). As the liquid passes through the resin bed, monovalent, bivalent, trivalent, and / or multivalent anions present in the liquid comprising inulin are captured by the resin, while anions, preferably monovalent anions such as chloride ions, are released into the liquid.

[0075] As used herein, the term "cation exchange" generally refers to ion exchange wherein cation exchange resins are employed. These resins contain negatively charged functional groups that selectively exchange cations such as sodium ions (Na+) for calcium (Ca2+), potassium (K+) and magnesium (Mg2+) ions in the liquid comprising inulin (i.e. these cations are replaced by for instance Na+and / or K+). Alternatively, for instance a K+based cation exchanger can be used. As the liquid passes through the resin bed, monovalent, bivalent, trivalent, and / or multivalent cations present in the liquid comprising inulin, such as calcium and magnesium ions are captured by the resin, while cations, preferably monovalent cations, such as sodium ions, are released into the liquid comprising inulin. It will be understood that at least part of the ions are exchanged, but that a complete (e.g. 100%) exchange is not required.

[0076] In exemplary embodiments, the method for purifying a liquid comprising inulin, comprises the steps of:

[0077] (a) providing a liquid comprising inulin, and (monovalent, bivalent and / or multivalent) anions (preferably also including for instance (conjugate bases of) organic acids, such as citrate, malate, oxalate, and / or lactate) and / or (monovalent, bivalent and / or multivalent) cations, and / or a combination thereof;

[0078] (b) subjecting the liquid to anion exchange and cation exchange step with one or more ion exchanger, wherein anions in said liquid are exchanged for a single monovalent anion, preferably Cl’, and cations are exchanged for a single monovalent cation, preferably Na+;

[0079] (c) subjecting the treated liquid to at least one nanofiltration treatment, preferably comprising at least one concentration step and at least one diafiltration step, to obtain a nanofiltration retentate fraction comprising purified inulin and a nanofiltration permeate fraction.

[0080] In embodiments of the methods as taught herein, e.g. as in any one of the aspects 1 to 14 stated above, the ion-exchange treatment exchanges the (monovalent, bivalent and / or multivalent) anions (including for instance (conjugate bases of) organic acids, such as malate, citrate, lactate, and / or oxalate) present in the liquid for one or more, preferably a single species of anions and exchanges the (monovalent, bivalent and / or multivalent) cations present in the liquid for one or more, preferably a single species of cations. In embodiments, the anions from the ion exchange are monovalent anions and the cations are monovalent cations. Examples of monovalent cations include, but are not limited to, sodium ion (Na+), potassium ion (K+), hydrogen ion (H+). On the contrary, monovalent anions typically refer to negatively charged atoms, radicals, or groups of atoms with a valence of -1. Examples of monovalent anions include, but are not limited to, chloride ion (Cl-), bromide ion (Br“), iodide ion (I-), fluoride ion (F“), hydroxide ion (OH“). Preferably, the monovalent cations comprise or consist of sodium ions and the monovalent anions comprise or consist of chloride ions.

[0081] In embodiments of the methods as taught herein, e.g. as in any one of the aspects 1 to 14 stated above, the total quantity of ions in the liquid after ion-exchange treatment is higher compared to the total quantity of ions in the liquid prior to ion-exchange treatment. For example, when a liquid comprising bivalent cations and anions is subjected to ion-exchange treatment one bivalent cation will be exchanged for two monovalent cations and one bivalent anion will be exchanged for two monovalent anions, and thereby elevate the total quantity of ions, that is both cations and anions. In exemplary embodiments, the method for purifying a liquid comprising inulin comprises the steps of:

[0082] (a) providing a liquid comprising inulin, and (monovalent, bivalent and / or multivalent) anions (optionally also including (conjugate bases of) organic acids such as malate, citrate, oxalate, and / or lactate) and / or (monovalent, bivalent and / or multivalent) cations, and / or a combination thereof;

[0083] (b) subjecting the liquid to one or more ion-exchange treatment with one or more ion exchanger, wherein anions in said liquid are exchanged for a chloride ions and cations are exchanged for a sodium ion;

[0084] (c) subjecting the treated liquid to at least one nanofiltration treatment, preferably comprising at least one concentration step and at least one diafiltration step, to obtain a nanofiltration retentate fraction comprising purified inulin and a nanofiltration permeate fraction.

[0085] In embodiments of the methods as taught herein, e.g. as in any one of the aspects 1 to 14 stated above, the diafiltration step removes at least 50% of the monovalent anions and cations species present in the liquid after step (b), preferably at least 51%, 52%, 53%, 54%, 55%, 56%, 57%, 58%, 59%, 60%, 61%, 62%, 63%, 64%, 65%, 66%, 67%, 68%, 69%, 70%, 71%, 72%, 73%, 74%, 75%, 76%, 77%, 78%, 79%, 80%, 81%, 82%, 83%, 84%, and most preferably at least 85%.

[0086] In embodiments of the methods as taught herein, e.g. as in any one of the aspects 1 to 14 stated above, the diafiltration step removes at least 50% of the monovalent anions and cations species exchanged during the ion-exchange treatment (step b), preferably at least 51%, 52%, 53%, 54%, 55%, 56%, 57%, 58%, 59%, 60%, 61%, 62%, 63%, 64%, 65%, 66%, 67%, 68%, 69%, 70%, 71%, 72%, 73%, 74%, 75%, 76%, 77%, 78%, 79%, 80%, 81%, 82%, 83%, 84%, and most preferably at least 85%. In embodiments of the methods as taught herein, e.g. as in any one of the aspects 1 to 14 stated above, prior to step c) and after b) the liquid can be heated to about 110 degrees Celsius and cooled to at most about 65 degrees Celsius. In embodiments, the methods as taught herein comprise heating the liquid to a temperature of at most about 81°C, at most about 82°C, at most about 83°C, at most about 84°C, at most about 85°C, at most about 86°C, at most about 87°C, at most about 88°C, at most about 89°C, at most about 90°C, at most about 91°C, at most about 92°C, at most about 93°C, at most about 94°C, at most about 95°C, at most about 96°C, at most about 97°C, at most about 98°C, at most about 99°C, at most about 100°C, at most about 101°C, at most about 102°C, at most about 103°C, at most about 104°C, at most about 105°C, at most about 106°C, at most about 107°C, at most about 108°C, at most about 109°C, or at most about 110°C. In embodiments, the methods as taught herein comprise cooling the liquid to a temperature of at most 35°C, at most 36°C, at most 37°C, at most 38°C, at most 39°C, at most 40°C, at most 41°C, at most 42°C, at most 43°C, at most 44°C, at most 45°C, at most 46°C, at most 47°C, at most 48°C, at most 49°C, at most 50°C, at most 51°C, at most 52°C, at most 53°C, at most 54°C, to at most 55°C, at most 56°C, at most 57°C, at most 58°C, at most 59°C, at most 60°C, at most 61°C, at most 62°C, at most 63°C, at most 64°C, at most 65°C, at most 66°C, at most 67°C, at most 68°C, at most 69°C, or at most 70°C prior to step c).

[0087] The term "cooled" as used herein refers to the action or process of making the liquid (e.g., the treated liquid) colder (i.e., less warm), i.e. decreasing the temperature of the liquid (e.g., the inulin juice or composition) from a higher temperature (e.g., between about 80°C and about 110°C) to a lower temperature (e.g. between about 35°C and about 70°C).

[0088] To cool a composition, the composition may be conveniently exposed to an environment having the desired temperature, e.g., a temperature around of just below the temperature for the nanofiltration treatment, typically between about 60°C and about 70°C, or the composition may be conveniently exposed to an environment having a temperature which is decreasing gradually or stepwise until the desired temperature is reached.

[0089] The recitation "cooling a composition to a given temperature (such as between about 60°C and 70°C)" as used herein refers to decreasing (i.e., lowering) the temperature of the composition (from a higher temperature) to said given temperature.

[0090] In embodiments of the methods as taught herein, e.g. as in any one of the aspects 1 to 14 stated above, the cooling speed may be linear during the whole cooling step or during at least part of the cooling step. In embodiments, the cooling speed may be linear or not linear.

[0091] The methods as taught herein comprise the step (c), subjecting the treated liquid to at least one nanofiltration treatment, to obtain a nanofiltration retentate fraction comprising purified inulin and a nanofiltration permeate fraction. In preferred embodiments, nanofiltration treatment comprises at least one concentration step and at least one diafiltration step. In embodiments, the treated liquid can be subjected to the concentration step and diafiltration step simultaneously or subsequently. In case the concentration step and diafiltration step are performed simultaneously, both steps can be performed on the same membrane. In certain embodiments, the methods as taught herein comprise the step (c), subjecting the treated liquid to at least one nanofiltration treatment to obtain a nanofiltration retentate fraction comprising purified inulin and a nanofiltration permeate fraction, wherein the (concentrated) retentate fraction comprising purified inulin is diluted, preferably with (demineralized) water, such as reverse osmosis permeate fraction as described herein elsewhere. Dilution is necessary to maintain appropriate inulin concentration and is required in case multiple consecutive nanofiltration steps are performed. In embodiments of the methods as taught herein, e.g. as in any one of the aspects 1 to 14 stated above, the methods comprise a nanofiltration treatment comprising at least two subsequent nanofiltration or diafiltration steps, at least three subsequent nanofiltration or diafiltration steps, at least four subsequent nanofiltration or diafiltration steps, or at least five subsequent nanofiltration or diafiltration steps (optionally following the concentration step). The retentate of each nanofiltration step may be diluted (such as with water from the water purification, such as reverse osmosis permeate as described herein elsewhere).

[0092] In another embodiment of the methods as taught herein, e.g. as in any one of the aspects 1 to 14 stated above, the methods comprise a nanofiltration treatment, preferably comprising at least one concentration step and at least one diafiltration step performed subsequently and followed by at least one subsequent diafiltration step, at least two subsequent diafiltration steps, at least three subsequent diafiltration steps, at least four subsequent diafiltration steps, or at least five subsequent diafiltration steps.

[0093] In another embodiment of the methods as taught herein, e.g. as in any one of the aspects 1 to 14 stated above, the methods comprise a nanofiltration treatment, comprising at least one concentration step and at least one diafiltration step performed simultaneously and followed by at least one subsequent diafiltration step, at least two subsequent diafiltration steps, at least three subsequent diafiltration steps, at least four subsequent diafiltration steps, or at least five subsequent diafiltration steps.

[0094] As used herein, the term "nanofiltration" relates to a membrane-based separation process that selectively removes particles, ions, and molecules from a liquid stream based on their size and charge. Nanofiltration utilizes nanofiltration membranes with pore sizes ranging from 1 to 10 nanometers. These membranes allow the passage of water molecules and some smaller ions while blocking larger particles, ions, and organic molecules. Nanofiltration equipment can be carried out in concentration mode, whereby the liquid is removed without the addition of fresh solvent, thereby reducing the volume of retentate (and hence concentrating the retentate), or in diafiltration mode, whereby a solvent is added as permeate is removed, thereby enabling buffer exchange without altering the concentration of retained molecules. Also consecutively applying one or more concentration and diafiltration modes are possible (in either order). In embodiment, nanofiltration employs a specialized nanofiltration membrane with a molecular weight cut-off ranging from 100 to 600 Daltons (Da), from 110 to 590 Da, from 120 to 580 Da, from 130 to 570 Da, from 140 to 560 Da, from 145 to 550, from 150 to 500 Da, from 150 to 450 Da, from 150 to 400 Da, from 150 to 350 Da, preferably from 150 to 300 Da. In some embodiments, the nanofiltration treatment comprises at least one concentration step. In some embodiments, the nanofiltration treatment comprises one concentration step. In some embodiments, the nanofiltration treatment comprises more than one concentration step. In some embodiments, the nanofiltration treatment comprises at least one diafiltration step. In some embodiments, the nanofiltration treatment comprises at least two diafiltration steps. In some embodiments, the nanofiltration treatment comprises at least three diafiltration steps. In some embodiments, the nanofiltration treatment comprises at least one concentration step and at least one diafiltration step. In some embodiments, the nanofiltration treatment comprises at least one concentration step and at least two diafiltration steps. In some embodiments, the nanofiltration treatment comprises one concentration step and two diafiltration steps. The order of the steps may vary (i.e. first concentration and then diafiltration or vice versa, or in case of multiple concentration and / or diafiltration steps these steps may be intermixed). In certain embodiments, the nanofiltration treatment comprises in the following order one concentration step and two diafiltration steps. As described herein elsewhere, preferably the reverse osmosis permeate (as described herein elsewhere) may be added during one or more (preferably all) of the diafiltration steps.

[0095] In certain embodiments, nanofiltration is carried out by consecutively filtering the liquid which has been subjected to the ion-exchange liquid in different (subsequent) filtration steps, in which a first filtration step concentrates the retentate. Subsequent filtration step(s) may then effect solvent exchange (without further concentration) by adding new solvent (in particular reverse osmosis permeate) prior to or during the subsequent filtration step(s). The amount of solvent added allows to tailor the retentate concentration if so desired. These subsequent filtration steps in effect can be considered diafiltration steps.

[0096] In exemplary embodiments of the methods as taught herein, e.g. as in any one of the aspects 1 to 14 stated above, the method comprises the steps of:

[0097] (a) providing a liquid comprising inulin, and (monovalent, bivalent and / or multivalent) anions (optionally also including (conjugate bases of) organic acids such as malate, citrate, oxalate, and / or lactate) and / or (monovalent, bivalent and / or multivalent) cations, and / or a combination thereof;

[0098] (b) subjecting the liquid to one or more ion-exchange treatment with one or more ion exchanger, wherein anions in said liquid are exchanged for a single species of monovalent anions (preferably chloride ions) and cations are exchanged for a single species of monovalent cations (preferably sodium ions); (c) subjecting the treated liquid to at least one nanofiltration treatment, preferably comprising at least one concentration step and at least one diafiltration step performed simultaneously, to obtain a nanofiltration retentate fraction comprising purified inulin and a nanofiltration permeate fraction.

[0099] In exemplary embodiments of the methods as taught herein, e.g. as in any one of the aspects 1 to 14 stated above, the method comprises the steps of:

[0100] (a) providing a liquid comprising inulin, and (monovalent, bivalent and / or multivalent) anions (optionally also including (conjugate bases of) organic acids such as malate, citrate, oxalate, and / or lactate) and / or (monovalent, bivalent and / or multivalent) cations, and / or a combination thereof;

[0101] (b) subjecting the liquid to one or more ion-exchange treatment with one or more ion exchanger, wherein anions in said liquid are for a single species of monovalent anions (preferably chloride ions) and cations are exchanged for a single species of monovalent cations (preferably sodium ions);

[0102] (c) subjecting the treated liquid to at least one nanofiltration treatment, preferably comprising at least one concentration step and at least one diafiltration step performed subsequently, to obtain a nanofiltration retentate fraction comprising purified inulin and a nanofiltration permeate fraction.

[0103] In embodiments of the methods as taught herein, e.g. as in any one of the aspects 1 to 14 stated above, the nanofiltration retentate fraction is subjected to at least one subsequent diafiltration step, at least two subsequent diafiltration steps, at least three subsequent diafiltration steps, at least four subsequent diafiltration steps, or at least five subsequent diafiltration steps. In this connection, advantageously the reverse osmosis permeate, as described herein elsewhere, can be used for diafiltration.

[0104] In exemplary embodiments of the methods as taught herein, e.g. as in any one of the aspects 1 to 14 stated above, the method comprises the steps of:

[0105] (a) providing a liquid comprising inulin, and (monovalent, bivalent and / or multivalent) anions (optionally also including (conjugate bases of) organic acids such as malate, citrate, oxalate, and / or lactate) and / or (monovalent, bivalent and / or multivalent) cations, and / or a combination thereof;

[0106] (b) subjecting the liquid to one or more ion-exchange treatment with one or more ion exchanger, wherein anions in said liquid are for a single species of monovalent anions (preferably chloride ions) and cations are exchanged for a single species of monovalent cations (preferably sodium ions); (c) subjecting the treated liquid to at least one nanofiltration treatment, preferably comprising at least one concentration step and at least two subsequent diafiltration steps, to obtain a nanofiltration retentate fraction comprising purified inulin and a nanofiltration permeate fraction.

[0107] In embodiments of the methods as taught herein, e.g. as in any one of the aspects 1 to 14 stated above, the nanofiltration treatment removes up to substantially 100%, up to 99% up to 98 percent (%), up to 97%, up to 96%, up to 95%, up to 94%, up to 93%, up to 92%, up to 91%, up to 90%, up to 89%, up to 88%, up to 87%, up to 86%, up to 85%, up to 84%, up to 83%, up to 82%, up to 81%, up to 80%, up to 79%, up to 78%, up to 77%, up to 76%, up to 75%, up to 74%, up to 73%, up to 72%, up to 71%, up to 70%, up to 69%, up to 68%, up to 67%, up to 66%, up to 65%, up to 64%, up to 63%, up to 62%, up to 61%, up to 60%, up to 59%, up to 58%, up to 57%, up to 56%, up to 55%, of the ionic load (in mEq / kg dry matter) of the treated liquid.

[0108] In embodiments of the methods as taught herein, e.g. as in any one of the aspects 1 to 14 stated above, the nanofiltration treatment removes at least 50 percent (%), at least 51%, at least 52%, at least 53%, at least 54%, at least 55%, at least 56%, at least 57%, at least 58%, at least 59%, at least 60%, at least 61%, at least 62%, at least 63%, at least 64%, at least 65%, at least 66%, at least 67%, at least 68%, at least 69%, at least 70%, at least 71%, at least 72%, at least 73%, at least 74%, at least 75%, at least 76%, at least 77%, at least 80%, at least 81%, at least 82%, at least 83%, at least 84%, at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95% of the ionic load (in mEq / kg dry matter) from the treated liquid.

[0109] In embodiments of the methods as taught herein, e.g. as in any one of the aspects 1 to 14 stated above, the nanofiltration treatment removes between 50 percent (%) and substantially 100%, between 50% and 98%, between 55% and 97%, between 60% and 96%, between 65% and 95%, between 70% and 94%, between 75% and 93%, between 80% and 92%, between 85% and 91% of the ionic load (in mEq / kg dry matter) from the treated liquid.

[0110] In embodiments of the methods as taught herein, e.g. as in any one of the aspects 1 to 14 stated above, during the nanofiltration treatment a membrane is used for filtration of the treated liquid. In embodiments, a transmembrane pressure (TMP) of at least 7.0 bar, at least 7.5 bar, at least 8.0 bar, at least 8.5 bar, at least 9.0 bar, at least 9.5 bar, at least 10.0 bar, at least 10.5 bar, at least 11 bar is applied.

[0111] As used herein, the term "transmembrane pressure" typically refers to the pressure difference that exists across the membrane during nanofiltration. This pressure gradient drives the movement of the treated liquid through the membrane while retaining ions. The transmembrane pressure can be calculated by taking the average of the pressure on the feed (inlet) side of the membrane and the pressure on the retentate (outlet) side. From this average pressure, the pressure in the permeate (the portion that passes through the membrane) compartment is subtracted. Mathematically, TMP can be represented as:

[0112] TMP = ((P_feed + P_retentate) / 2) - P_permeate

[0113] Where:

[0114] • P_feed is the pressure on the feed side of the membrane (inlet pressure).

[0115] • P_retentate is the pressure on the retentate side of the membrane (outlet pressure).

[0116] • P_permeate is the pressure in the permeate compartment.

[0117] In embodiments of the methods as taught herein, e.g. as in any one of the aspects 1 to 14 stated above, the nanofiltration membrane used, for filtration of the treated liquid during nanofiltration treatment, can remove bivalent and multivalent ions from the treated liquid. In embodiments, the nanofiltration membrane used, for filtration of the treated liquid during nanofiltration treatment, can remove single monovalent anions, such as chloride. In embodiments, the nanofiltration membrane used, for filtration of the treated liquid during nanofiltration treatment, can remove some single monovalent cations, such as sodium and potassium.

[0118] In a preferred embodiment of the methods as taught herein, e.g. as in any one of the aspects 1 to 14 stated above, the membrane is used for filtration of the treated liquid during nanofiltration treatment comprises a porosity of 150 / 300 Da.

[0119] Various types of membranes can be utilized in nanofiltration treatment. Some examples of suitable membranes include, but not limited to, polymeric membranes made of synthetic polymers such as polyamide, microporous polysulfone, and polyethersulfone. In embodiments, the treated liquid is subjected to nanofiltration at a temperature of at most 45°C, at most 46°C, at most 47°C, at most 48°C, at most 49°C, at most 50°C, at most 51°C, at most 52°C, at most 53°C, at most 54°C, to at most 55°C, at most 56°C, at most 57°C, at most 58°C, at most 59°C, at most 60°C, at most 61°C, at most 62°C, at most 63°C, at most 64°C, at most 65°C, at most 66°C, at most 67°C, at most 68°C, at most 69°C, or at most 70°C.

[0120] In embodiments of the methods as taught herein, e.g. as in any one of the aspects 1 to 14 stated above, the treated liquid is subjected to nanofiltration at a temperature of at least 40°C, at least 41°C, at least 42°C, at least 43°C, at least 44°C, at least 45°C, at least 46°C, at least 47°C, at least 48°C, at least 49°C, at least 50°C, at least 51°C, at least 52°C, at least 53°C, at least 54°C, to at least 55°C, at least 56°C, at least 57°C, at least 58°C, at least 59°C. In embodiments of the methods as taught herein, e.g. as in any one of the aspects 1 to 14 stated above, the treated liquid is subjected to nanofiltration at a temperature between 40°C and 70°C, between 41°C and 69°C, between 42°C and 68°C, between 43°C and 67°C, between 44°C and 66°C, between 45°C and 65°C, between 46°C and 64°, between 47°C and 63°C, between 48°C and 62°C, between 49°C and 61°C, between 50°C and 60°, or between 52°C and 58°C.

[0121] Performing nanofiltration at a temperature above 60 degrees Celsius offers the advantage of reducing the potential for microorganism growth. By incorporating this higher temperature in the nanofiltration treatment, the risk of microbial contamination is minimized, ensuring safer purification methods.

[0122] In embodiments of the methods as taught herein, e.g. as in any one of the aspects 1 to 14 stated above, the treated liquid is subjected to nanofiltration at a pH between 3.0 and 9.0, between 3.5 and 8.5, between 4.0 and 8.0, between 4.5 and 7.5, between 5.0 and 7.0, or between 5.5 and 6.5.

[0123] In exemplary embodiments of the methods as taught herein, e.g. as in any one of the aspects 1 to 14 stated above, the method comprises the steps of:

[0124] (a) providing a liquid comprising inulin, and (monovalent, bivalent and / or multivalent) anions (optionally also including (conjugate bases of) organic acids such as malate, citrate, oxalate, and / or lactate) and (monovalent, bivalent and / or multivalent) cations, and / or a combination thereof;

[0125] (b) subjecting the liquid to one or more ion-exchange treatment with one or more ion exchanger, wherein anions in said liquid are for a single species of monovalent anions (preferably chloride ions) and cations are exchanged for a single species of monovalent cations (preferably sodium ions);

[0126] (c) subjecting the treated liquid at a temperature of at most 70°C to at least one nanofiltration treatment, preferably comprising at least one concentration step and at least one diafiltration step, to obtain a nanofiltration retentate fraction comprising purified inulin and a nanofiltration permeate fraction.

[0127] In embodiments of the methods as taught herein, e.g. as in any one of the aspects 1 to 14 stated above, the nanofiltration retentate fraction, obtained after the nanofiltration treatment, comprises purified inulin, and less than 50 percent (%) of the monovalent, bivalent, multivalent, single species of monovalent cations and single species of monovalent anions compared to the treated liquid prior to nanofiltration treatment. In embodiments, the nanofiltration retentate fraction, obtained after the nanofiltration treatment, comprises purified inulin, and less than 45%, less than 40%, less than 38%, less than 35%, less than 30%, less than 25%, less than 20%, less than 17%, less than 16%, or less than 15% of the monovalent, bivalent, multivalent, single species of monovalent cations and single species of monovalent anions compared to the treated liquid prior to nanofiltration treatment.

[0128] In embodiments of the methods as taught herein, e.g. as in any one of the aspects 1 to 14 stated above, after nanofiltration treatment, the nanofiltration retentate fraction is subjected to a demineralisation step to remove cation and anions. In embodiments, after nanofiltration treatment, the nanofiltration retentate fraction is demineralised to remove the sodium and chloride ions from the nanofiltration retentate fraction to obtain a demineralised nanofiltration retentate fraction comprising inulin.

[0129] As used herein, the term "demineralisation" generally refers to the process of selectively removing ions, such as calcium, magnesium, sodium, potassium, and chloride ions, from the nanofiltration retentate fraction, to produce deionized nanofiltration retentate fraction. This process can involve the use of ion exchange resins or other specialized materials that selectively adsorb and remove ions from the nanofiltration retentate fraction, resulting in a purified nanofiltration retentate fraction with reduced mineral content, e.g. reduced concentration of calcium, magnesium, sodium, potassium, and chloride.

[0130] Prior to step a), the methods as taught herein may comprise the step of providing an inulin containing material such as chicory roots.

[0131] As used herein, the term "inulin" refers to a mixture of oligo- and / or polysaccharides of fructose which may have a terminal glucose. Inulins belong to a class of fibres known as fructans. In an embodiment, inulin can be represented, depending from the terminal carbohydrate unit, by the general formula GFnand / or Fm, wherein G represents a glucose unit, F represents a fructose unit, n is an integer representing the number of fructose units linked to the terminal glucose unit, and m is an integer representing the number of fructose units linked to each other in the carbohydrate chain, preferably wherein n is at least 2, and m is at least 2. Inulins as taught herein encompass inulins with a terminal glucose which are also referred as alpha-D-glucopyranosyl-[beta-D- fructofuranosyl](n-l)-D-fructofuranosides, as well as inulins without glucose which are also referred as beta-D-fructopyranosyl-[D-fructofuranosyl](n-l)-D-fructofuranosides. Suitable saccharide chains of inulin from plant origin as taught herein can have a degree of polymerisation ranging from 2 to about 60. Inulin can be a liquid or a powder product.

[0132] As used herein, the terms "degree of polymerization" or "DP" relates to the number of monosaccharide residues present in an oligo- or polysaccharide. Often also the parameter average degree of polymerization is used. The degree of polymerization is a measure of molecular weight (MW). The DP can be calculated as the ratio of the total MW of the polymer or oligomer and the MW of the repeating units.

[0133] The average degree of polymerization (av DP) of a (polydispersed) oligo- or polysaccharide mixture is the mean of the degree of polymerization (DP) of all the molecules present in the saccharide mixture. The average degree of polymerization herein, unless otherwise specified, is calculated based on the number of molecules for each DP: av DPn or average degree of polymerization by number as described herein below.

[0134] Determination of the molecular mass distribution of the inulin sample is done by High Performance Anion Exchange Chromatography coupled with Pulse Amperometric Detection (HPAEC-PAD) on a Thermofisher-Dionex ICS 5000 chromatographic system. Separation of the various chain lengths is achieved by a Carbopac PA100 2mm *250 mm (+ guard) at 30°C with a flow rate of 0.25 ml / min. Sodium hydroxide 160 mM is used as eluent. A gradient of sodium acetate during the run allows to separate the various chain lengths.

[0135] Inulin mixture standards at different concentrations are injected in order to draw the calibration curves and to assign the peaks in the chromatogram based on the retention time of the standard. The calibration curves allow determining the concentration of each molecular species in the sample.

[0136] From the obtained concentration distribution, the average polymerization degree in number Dpnis calculated as

[0137] Where Ni is the number of molecules having i residue and Dpi the number of residues.

[0138] In an embodiment, the inulin as described herein is derived from or isolated from plants, i.e. it is of plant origin, preferably from chicory (Cichorium intybus).

[0139] In an embodiment, the liquid comprising inulin is obtained by hot water extraction. In a preferred embodiment, industrial production of inulin from for instance chicory root involves extraction by hot water. However, ions, free sugars, impurities (e.g. protein), solids are co-extracted.

[0140] As used herein, the term "free sugars" refers to monosaccharides and / or disaccharides. Free sugars may for instance be present in plants, plant material, or plant homogenates, extracts, or isolates, or fractionated plant material. In an embodiment, the term "free sugars" as used herein refers to hexose mono- or di-saccharides, preferably hexose mono- or di-saccharides. Preferably, the term "free sugars" encompasses fructose, glucose, and sucrose (saccharose). Accordingly, in an embodiment, free sugars comprise or consist or consist essentially of fructose. In another embodiment, free sugars comprise or consist or consist essentially of glucose. In yet another embodiment, free sugars comprise or consist or consist essentially of sucrose. In a further embodiment, free sugars comprise or consist of fructose and glucose. In yet another embodiment, free sugars comprise or consist or consist essentially of fructose and sucrose. In another embodiment, free sugars comprise or consist or consist essentially of glucose and sucrose. In yet a further embodiment, free sugars comprise or consist or consist essentially of fructose, glucose, and sucrose.

[0141] As used herein, the term "liquid comprising inulin" refers to any type of liquid composition which comprises inulin, ions and optionally free sugars and / or impurities. Preferably, the liquid comprising inulin is an aqueous composition (i.e. a composition comprising water and a certain amount of inulin, dissolved and / or dispersed therein). Preferably, the liquid comprising inulin as described herein refer to extracts, which are enriched in inulin compared to the source material it is derived from. Inulin extraction may for instance involve putting plant material in hot water followed by concentration (e.g. evaporation). The liquid comprising inulin can comprise between 6 and 20grams of carbohydrates / 100 g, preferably between 7 and 18 grams of carbohydrates / 100 g of liquid comprising inulin, such as between 8 and 15 grams of carbohydrates / 100 g liquid comprising inulin. In embodiments, the inulin composition (also called inulin juice) may comprise inulin, ions such as anions, including for instance monovalent anions, bivalent anions, multivalent anions, and cations, including for instance monovalent cations, bivalent cations, multivalent cations, free sugars (e.g., glucose, fructose, sucrose), and impurities (e.g., proteins). In embodiments, the inulin composition may (further) comprise organic acids (such as lactic acid, citric acid, oxalic acid, and / or malic acid) and / or conjugate bases of organic acids (such as malate, citrate, oxalate, and / or lactate). In embodiments, the inulin composition may comprise inulin and monovalent anions, bivalent anions, multivalent anions, monovalent cations, bivalent cations, multivalent cations. In embodiments, the inulin composition may comprise inulin and ions such as monovalent anions, bivalent anions, multivalent anions, monovalent cations, bivalent cations, multivalent cations.

[0142] In embodiments of the methods as taught herein, e.g. as in any one of the aspects 1 to 14 stated above, the methods may further comprise one or more water purification process steps after step c). In certain embodiments, the nanofiltration permeate fraction is subjected to one or more water purification processes. Examples of water purification processes include, but are not limited to, activated carbon filtration, membrane filtration (such as reverse osmosis and electrodialysis), demineralization. Preferably, the water purification comprises reverse osmosis. In exemplary embodiments of the methods as taught herein, e.g. as in any one of the aspects 1 to

[0143] 14 stated above, the method comprises the steps of:

[0144] (a) providing a liquid comprising inulin, and (monovalent, bivalent and / or multivalent) anions (optionally also including (conjugate bases of) organic acids such as malate, citrate, oxalate, and / or lactate) and (monovalent, bivalent and / or multivalent) cations, and / or a combination thereof;

[0145] (b) subjecting the liquid to one or more ion-exchange treatment with one or more ion exchanger, wherein anions in said liquid are for a single species of monovalent anions (preferably chloride ions) and cations are exchanged for a single species of monovalent cations (preferably sodium ions);

[0146] (c) subjecting the treated liquid to at least one nanofiltration treatment, preferably comprising at least one concentration step and at least one diafiltration step, to obtain a nanofiltration retentate fraction comprising purified inulin and a nanofiltration permeate fraction;

[0147] (d) subjecting the nanofiltration permeate fraction to one or more water purification process. In embodiments, the water purification process is a reverse osmosis (RO) treatment to obtain a reverse osmosis retentate fraction and a reverse osmosis permeate fraction. In embodiments, the nanofiltration permeate fraction is subjected reverse osmosis treatment to obtain a reverse osmosis retentate fraction and a reverse osmosis permeate fraction.

[0148] As used herein, the term "reverse osmosis" ("RO") typically refers to water purification process utilizing a semipermeable membrane to remove ions, molecules, impurities and larger particles from water. In embodiment, RO employs a specialized RO membrane with a molecular weight cutoff under 300 Daltons (Da), under 290 Da, under 280 Da, under 270 Da, under 260 Da, under 250 Da, under 240 Da, under 230 Da, under 220 Da, under 210 Da, under 200 Da, under 190 Da, under 180 Da, under 170 Da, under 160 Da, under 150 Da. In a preferred embodiment, the RO membrane comprises a molecular weight cut-off under 200 Da. In embodiment, RO employs an RO membrane with pore sizes below 2 nanometers (nm), below 1.5 nm, below 1.4 nm, below 1.3 nm, below 1.2 nm, below 1.1 nm, below 1.0 nm, below 0.9 nm, below 0.8 nm, below 0.7 nm, below 0.6 nm, below 0.5 nm. In a preferred embodiment, the RO membrane comprises a pore size below 1.0 nm. Various types of membranes can be utilized in RO treatment. Some examples of suitable membranes include, but not limited to, polymeric membranes made of synthetic polymers such, polyamide, and microporous polysulfone.

[0149] In RO treatment, pressure can be applied to the nanofiltration permeate fraction, forcing it through the membrane, which allows water molecules to pass while retaining dissolved solids, contaminants, impurities from the nanofiltration permeate fraction when passing through the membrane. After RO treatment a reverse osmosis retentate fraction and a reverse osmosis permeate fraction is obtained, wherein the reverse osmosis permeate fraction can comprise purified water with reduced levels of ions, dissolved solids, contaminants, and impurities and wherein the reverse osmosis retentate fraction can comprise ions, dissolved solids, contaminants, and impurities retained during RO treatment.

[0150] In exemplary embodiments of the methods as taught herein, e.g. as in any one of the aspects 1 to 14 stated above, the method comprises the steps of:

[0151] (a) providing a liquid comprising inulin, and (monovalent, bivalent and / or multivalent) anions (optionally also including (conjugate bases of) organic acids such as malate, citrate, oxalate, and / or lactate) and (monovalent, bivalent and / or multivalent) cations, and / or a combination thereof;

[0152] (b) subjecting the liquid to one or more ion-exchange treatment with one or more ion exchanger, wherein anions in said liquid are for a single species of monovalent anions (preferably chloride ions) and cations are exchanged for a single species of monovalent cations (preferably sodium ions);

[0153] (c) subjecting the treated liquid to at least one nanofiltration treatment, preferably comprising at least one concentration step and at least one diafiltration step, to obtain a nanofiltration retentate fraction comprising purified inulin and a nanofiltration permeate fraction;

[0154] (d) subjecting the nanofiltration permeate fraction is subjected to one or more reverse osmosis treatments, to obtain a reverse osmosis retentate fraction comprising mainly monovalent anions (introduced after ion exchange) and monovalent cations (introduced after ion exchange) and reverse osmosis permeate fraction comprises purified water with reduced levels of the single species of the monovalent anions and the single species of the monovalent cations.

[0155] In embodiments of the methods as taught herein, e.g. as in any one of the aspects 1 to 14 stated above, the reverse osmosis retentate fraction comprises monovalent anions (introduced after ion exchange) and the monovalent cations (introduced after ion exchange). In embodiments, the reverse osmosis retentate fraction comprises sodium ions and chloride ions. In embodiments, the reverse osmosis retentate fraction can be used in the ion-exchange treatment. In embodiments, at least a part of the reverse osmosis retentate fraction can be added to the one or more ion exchanger of step b). Preferably, the entire reverse osmosis retentate fraction can be added to the one or more ion exchanger of step b). In embodiments, at least part of the reverse osmosis retentate fraction is used to regenerate the one or more ion exchanger. Preferably, the entire reverse osmosis retentate fraction is used to regenerate the one or more ion exchanger of step b). An advantage is that the single species of monovalent anions and cations, such as sodium and chloride, can be recycled, resulting in a reduction in the amount of chemicals required for the method. An additional advantage is that the method results in less effluent to be treated, further reducing the environmental footprint. Moreover, it requires less energy, thereby contributing to overall cost savings. This not only improves efficiency but also contributes to environmental sustainability by minimizing chemical usage, reducing energy consumption and reducing the overall impact on nature.

[0156] In embodiments, the reverse osmosis retentate, which is enriched in the single species of monovalent salt introduced by the ion-exchange treatment, is preferably used for regeneration of the ion exchanger. By recycling the RO retentate in this way, the method advantageously transforms what would otherwise be a waste brine stream into a regenerant feedstock. This closed- loop operation significantly reduces the need for fresh regenerant chemicals, minimizes effluent discharge, and lowers the overall environmental footprint of the process.

[0157] In exemplary embodiments of the methods as taught herein, e.g. as in any one of the aspects 1 to 14 stated above, the method comprises the steps of:

[0158] (a) providing a liquid comprising inulin, and (monovalent, bivalent and / or multivalent) anions (optionally also including (conjugate bases of) organic acids such as malate, citrate, oxalate, and / or lactate) and (monovalent, bivalent and / or multivalent) cations, and / or a combination thereof;

[0159] (b) subjecting the liquid to one or more ion-exchange treatment with one or more ion exchanger, wherein anions in said liquid are for a single species of monovalent anions (preferably chloride ions) and cations are exchanged for a single species of monovalent cations (preferably sodium ions);

[0160] (c) subjecting the treated liquid to at least one nanofiltration treatment, preferably comprising at least one concentration step and at least one diafiltration step, to obtain a nanofiltration retentate fraction comprising purified inulin and a nanofiltration permeate fraction;

[0161] (d) subjecting the nanofiltration permeate fraction is subjected to one or more reverse osmosis treatments, to obtain a reverse osmosis retentate fraction comprising monovalent anions (introduced after ion exchange) and the monovalent cations (introduced after ion exchange) and reverse osmosis permeate fraction comprises purified water with reduced levels of the monovalent anions and the monovalent cations;

[0162] (e) Adding at least a part of the reverse osmosis retentate fraction to the one or more ion exchanger of step b) (i.e. using the RO retentate to regenerate the ion exchanger). In embodiments of the methods as taught herein, e.g. as in any one of the aspects 1 to 14 stated above, the reverse osmosis permeate fraction comprises purified water with reduced levels of ions, and optionally reduced levels of free sugars, dissolved solids, contaminants, and impurities. In embodiments, the reverse osmosis retentate fraction can be used in the ion-exchange treatment. In embodiments, at least a part of the reverse osmosis permeate fraction can be added to the nanofiltration treatment in step c). Preferably, the entire reverse osmosis permeate fraction can be added to the nanofiltration treatment in step c).ln embodiments, at least part of the reverse osmosis permeate fraction is used during or after the nanofiltration treatment. The reverse osmosis permeate fraction can be used to recycle water for nanofiltration treatment (such as to dilute the retentate fraction after nanofiltration). Preferably, the reverse osmosis permeate fraction is supplied before or during or after the diafiltration / nanofiltration step(s). In a preferred embodiment, the reverse osmosis permeate fraction is added to the treated liquid before the liquid comprising inulin passes through the membrane in the diafiltration / nanofiltration step. In case, the nanofiltration treatment comprises more than one diafiltration / nanofiltration step, the reverse osmosis permeate fraction can be added to the treated liquid or the diafiltered / nanofiltered liquid before each subsequent diafiltration / nanofiltration step.

[0163] Diafiltration requires significant amounts of water, with one volume of water needed per volume of product for each step. Consequently, recycling the reverse osmosis permeate fraction to reuse a substantial portion of water for diafiltration can have a significant positive impact on the environment. By recycling water internally, the volume of wastewater discharged into the environment is reduced. This lessens the burden on wastewater treatment. By implementing watersaving measures like recycling reverse osmosis permeate fraction, the invention contributes to water resilience and adaptation to changing environmental conditions. Saving water via inline recycling reverse osmosis permeate extends beyond individual industrial processes, contributing to broader environmental sustainability goals while fostering responsible water management practices.

[0164] In exemplary embodiments of the methods as taught herein, e.g. as in any one of the aspects 1 to 14 stated above, the method comprises the steps of:

[0165] (a) providing a liquid comprising inulin, and (monovalent, bivalent and / or multivalent) anions (optionally also including (conjugate bases of) organic acids such as malate, citrate, oxalate, and / or lactate) and (monovalent, bivalent and / or multivalent) cations, and / or a combination thereof;

[0166] (b) subjecting the liquid to one or more ion-exchange treatment with one or more ion exchanger, wherein anions in said liquid are for a single species of monovalent anions (preferably chloride ions) and cations are exchanged for a single species of monovalent cations (preferably sodium ions);

[0167] (c) subjecting the treated liquid to at least one nanofiltration treatment, preferably comprising at least one concentration step and at least one diafiltration step, to obtain a nanofiltration retentate fraction comprising purified inulin and a nanofiltration permeate fraction;

[0168] (d) subjecting the nanofiltration permeate fraction is subjected to one or more reverse osmosis treatments, to obtain a reverse osmosis retentate fraction comprising the single species of monovalent anions and the single species of monovalent cations and reverse osmosis permeate fraction comprises purified water with reduced levels of the single species of monovalent anions and the single species of monovalent cations;

[0169] (e) recirculating at least a portion of the reverse osmosis permeate fraction to the nanofiltration treatment in step c) (i.e. using the RO permeate fraction to dilute the retentate fraction of the nanofiltration).

[0170] In embodiments of the methods as taught herein, e.g. as in any one of the aspects 1 to 14 stated above, in step e) the reverse osmosis permeate fraction is at least partially used by recirculating at least a portion of the reverse osmosis permeate fraction to the nanofiltration treatment in step c). In embodiments, in step e) the reverse osmosis permeate fraction is at least partially used during at least one diafiltration step in step c). In embodiments, in step e) the reverse osmosis permeate fraction is at least partially used to dilute the retentate fraction of the nanofiltration during at least one diafiltration step in step c). In certain embodiments, in step e) the reverse osmosis permeate fraction is completely used to dilute the retentate fraction of the nanofiltration during at least one diafiltration step in step c). In certain embodiments, in step e) the reverse osmosis permeate fraction is completely used to dilute the retentate fraction of the nanofiltration during all diafiltration steps in step c).

[0171] In exemplary embodiments of the methods as taught herein, e.g. as in any one of the aspects 1 to 14 stated above, the method comprises the steps of:

[0172] (a) providing a liquid comprising inulin, and (monovalent, bivalent and / or multivalent) anions (optionally also including (conjugate bases of) organic acids such as malate, citrate, oxalate, and / or lactate) and (monovalent, bivalent and / or multivalent) cations, and / or a combination thereof;

[0173] (b) subjecting the liquid to one or more ion-exchange treatment with one or more ion exchanger, wherein anions in said liquid are for a single species of monovalent anions (preferably chloride ions) and cations are exchanged for a single species of monovalent cations (preferably sodium ions);

[0174] (c) subjecting the treated liquid to at least one nanofiltration treatment, preferably comprising at least one concentration step and at least one diafiltration step, to obtain a nanofiltration retentate fraction comprising purified inulin and a nanofiltration permeate fraction;

[0175] (d) subjecting the nanofiltration permeate fraction is subjected to one or more reverse osmosis treatments, to obtain a reverse osmosis retentate fraction comprising the single species of monovalent anions and the single species of monovalent cations and reverse osmosis permeate fraction comprises purified water with reduced levels of the single species of monovalent anions and the single species of monovalent cations;

[0176] (e) adding at least a part of the reverse osmosis retentate fraction to the one or more ion exchanger of step b) (i.e. using the RO retentate to regenerate the ion exchanger) and recirculating at least a portion of the reverse osmosis permeate fraction to the nanofiltration treatment in step c) (i.e. using the RO permeate fraction to dilute the retentate fraction of the nanofiltration).

[0177] In embodiments of the methods as taught herein, e.g. as in any one of the aspects 1 to 14 stated above, the methods may further comprise purification steps such as demineralization and optionally activated carbon filtration.

[0178] In embodiments of the methods as taught herein, e.g. as in any one of the aspects 1 to 14 stated above, the liquid comprising inulin of step (a) may be obtained by a method comprising or consisting of the steps of: (i) hot water extraction of an inulin containing material such as chicory roots; preferably hot water counter-current diffusion extraction of an inulin containing material; (ii) liquid / solid separation of the hot water extract, thereby obtaining a liquid fraction and a solid fraction; and (iii) filtration of the liquid fraction of step (ii), thereby recovering an inulin juice or composition, e.g., the filtrate of step (iii). In embodiments, the liquid / solid separation of the inulin juice / composition may be performed by filtration, centrifugation, or decantation; preferably the liquid / solid separation of the liquid comprising inulin is performed by filtration. Hence, in embodiments, the liquid comprising inulin of step (a) may be obtained using a method comprising or consisting of the steps of (i) hot water extraction of a inulin containing material such as chicory roots; preferably hot water counter-current diffusion extraction of an inulin containing material, (ii) filtration of the hot water extract; and (iii) filtration of the filtrate of step (ii), thereby recovering an liquid comprising inulin, e.g., the filtrate of step (iii). Another aspect of the invention relates to a system for purifying a liquid comprising inulin by performing the method of the invention as described herein, e.g. as in aspects 15 or 16 stated above.

[0179] Another aspect of the invention, e.g. as in aspects 15 or 16 stated above relates to a system for purifying a liquid comprising inulin by performing the method of the invention as described herein, and comprising the components described in the method of the invention as described herein.

[0180] Another aspect of the invention, e.g. as in aspects 15 or 16 stated above relates to a system for purifying a liquid comprising inulin, wherein the system comprises an ion-exchanger for exchanging anions and cations in the liquid comprising inulin for a single species of monovalent cations and a single species of monovalent anions, the ion-exchanger is connected (i.e. in fluid connection) to a nanofiltration means or apparatus for filtering the liquid comprising inulin, said single species of monovalent cations and said single species of monovalent anions.

[0181] As used herein, the term "nanofiltration means" can refer to means or equipment utilized for nanofiltration. In embodiments, nanofiltration means can include, but not limited to, membranes such as semi-permeable membranes, with pore sizes typically ranging from 1 to 10 nanometers, designed to selectively retain multivalent ions, large organic molecules, and / or certain contaminants while allowing smaller molecules and ions to pass through. In embodiments, nanofiltration membranes can comprise a molecular weight cut-off ranging from 100 to 600 Daltons (Da), from 110 to 590 Da, from 120 to 580 Da, from 130 to 570 Da, from 140 to 560 Da, from 145 to 550, from 150 to 500 Da, from 150 to 450 Da, from 150 to 400 Da, from 150 to 350 Da, preferably from 150 to 300 Da. The term "nanofiltration means" can also encompass membrane modules, filtration systems, and associated components configured to perform nanofiltration.

[0182] In embodiments of the system according to aspects 15 or 16 , the ion-exchanger comprises resin beads comprising at least two functional groups (at least one functional group with a negative charge and at least one functional group with a positive charge) capable of ion exchange. In embodiments, the ion-exchanger comprises an anion exchange and a cation exchange system.

[0183] In embodiments, the system according to aspects 15 or 16 further comprises a water purification means or equipment which is connected (i.e. in fluid connection) to nanofiltration means or apparatus and optionally connected to the ion-exchanger. In embodiments the water purification means or apparatus is a activated carbon filtration means or apparatus, a membrane filtration means or apparatus (such as a reverse osmosis or a electrodialysis means or apparatus) or a demineralization means or apparatus. Preferably, the water purification comprises reverse osmosis. In embodiments, the system according to aspects 15 or 16 further comprises a reverse osmosis means or apparatus which is connected (i.e. in fluid connection) to nanofiltration means or apparatus and optionally connected to the ion-exchanger.

[0184] As used herein, the term "reverse osmosis means" can refer to means or equipment utilized for reverse osmosis (RO), a membrane-based separation technology. In embodiment, reverse osmosis means can include, but not limited to, semipermeable membrane to remove ions, molecules, impurities and larger particles from water. In embodiment, RO membranes can comprise a molecular weight cut-off under 300 Daltons (Da), under 290 Da, under 280 Da, under 270 Da, under 260 Da, under 250 Da, under 240 Da, under 230 Da, under 220 Da, under 210 Da, under 200 Da, under 190 Da, under 180 Da, under 170 Da, under 160 Da, under 150 Da. In a preferred embodiment, the RO membrane comprises a molecular weight cut-off under 200 Da. In embodiment, RO employs an RO membrane with pore sizes below 2 nanometers (nm), below 1.5 nm, below 1.4 nm, below 1.3 nm, below 1.2 nm, below 1.1 nm, below 1.0 nm, below 0.9 nm, below 0.8 nm, below 0.7 nm, below 0.6 nm, below 0.5 nm. In a preferred embodiment, the RO membrane comprises a pore size below 1,0 nm. Some examples of RO membranes include, but not limited to, polymeric membranes made of synthetic polymers such, polyamide, and microporous polysulfone. In embodiment, reverse osmosis means can also encompass membrane modules, pressure vessels, pumps, valves, and associated components configured to perform reverse osmosis.

[0185] In embodiments, the system according to aspects 15 or 16 further comprises a demineralisation means or apparatus which is connected (i.e. in fluid connection) to the nanofiltration means or apparatus for demineralising the nanofiltration permeate fraction.

[0186] In embodiments of the system according to aspects 15 or 16, demineralisation means can include, but not limited to, ion exchange resins or other means that selectively adsorb and / or remove ions from a liquid, such as membrane filtration and electrodialysis.

[0187] In embodiments, the system according to aspects 15 or 16 further comprises at least one storage tank which is connected to the nanofiltration means or apparatus and / or the demineralisation means or apparatus for storing the nanofiltration permeate fraction and / or the demineralised nanofiltration permeate fraction.

[0188] The above aspects and embodiments are further supported by the following non-limiting examples. EXAMPLES

[0189] 1. Ion exchange with anion excha nge / cation exchange.

[0190] A sample, a liquid comprising inulin, underwent anion exchange followed by a cation exchange process to exchange ions present in the sample. The anion exchange process involved a resin containing chloride ions for exchanging anions in the sample, and the cation exchange process involved a resin containing sodium ions for exchanging cations in the sample. Samples were collected every 11% of total anion exchange process duration, and the juice was characterized (Figure 1) as follows:

[0191] Physical characterization of the juice:

[0192] The material that is soluble in the juice was analyzed for its dry matter (carbohydrate) by the usual grams dry matter / 100 g liquid comprising inulin measurement, for example using a Bellingham Stanley RFM 340 refractometer.

[0193] The pH and conductivity of the juice were measured in the usual way, e.g. using a pH meter and conductivity meter such as the WTW InoLab 740.

[0194] The colour and turbidity of a juice containing inulin are quantified by measuring the absorbance at 420 nm using a spectrophotometer in a 1 cm cuvette. The absorbance is measured on an unfiltered sample (ODNF) and on the same sample after passing through a membrane with a porosity of 0.2 pm (ODF). The colour and turbidity of the sample are expressed in ICUMSA units and are obtained by the following calculation where BV is the volumetric brix:

[0195] The concentration of protein content was determined using an organic elemental analyser based on the Dumas method, such as Elementar's Rapidmax or Variomax, to quantify the nitrogen content of a sample. A calibration curve was established by analysing a series of dilutions of a calibration solution containing EDTA. The calibration of the instrument is checked daily using a sample of known nitrogen concentration. Jones factor is then applied to convert nitrogen content into protein content.

[0196] The calcium concentration of the samples was measured by titration. First the dry matter of the sample was measured, then 5 ml of the sample was taken for the assay. Then 2.5 ml of ammonia and an indicator buffer were added. The sample is titrated with IM EDTA solution until a colour change from pink to green is observed. The concentrations of sodium and potassium are determined by flame spectrometry, such as the Corning 400 Flame photometer. A calibration curve was established by analysing a series of dilutions of the calibration solution containing: 2.5 parts per million (ppm) - 5ppm - 7.5 ppm sodium or 20 ppm - 100 ppm potassium. The blank was prepared using deionised water. For the powder sample, a solution of 10 grams of dry matter (carbohydrates) / 100 g of liquid comprising inulin in deionised water was prepared and used for the measurement.

[0197] The microbiological probity of powder sample was measured following the official norm:

[0198] NF V08-059 for yeast and mold quantification

[0199] ISO 4833 and NF EN ISO 6222 for total flora at 30°C and 55°C.

[0200] Lactate, chloride, malate, sulphate, oxalate, phosphate and citrate were measured using High Performance Anion Exchange Chromatography coupled with Pulse Amperometric Detection (HPAEC-PAD) on a Thermofisher-Dionex ICS 5000 chromatographic system with a suppressor such as AERS 2 mm with a suppressor current of 31 mA. The separation was achieved on ASH column (250 mm x 2 mm) at a temperature of 35°C. The mobile phase consisted of deionized water (A) and sodium hydroxyl at 160mM (B). Injection volume was 5 pl and flow rate was kept at 0.25 ml / min for a total run time of 14.10 min. The gradient programme was the following: 0 min 100% (A); 0 min - 4 min 95% (A); 4,5 min -8,5 min 90% (A); 8.5 min - 11.1 min 55% (A); 11.1 min -12.95 min 55% (A); 12.95 min - 13 min 0% (A); 13 min - 14 min 0% (A); 14,1 min 100% (A). Anions were identified by comparing retention time with available standards. Quantification was performed with a standard curve constructed by analysing a dilution series (30, 36, 46, 63, 100 and 240 times) of a stock solution containing 1800 ppm lactate, 1200 ppm chloride, 1800 ppm malate, 900 ppm sulphate, 150 ppm oxalate, 600 ppm phosphate and 1500 ppm citrate.

[0201] Sugar content i.e. glucose, fructose, saccharose content, was measured using High Performance Anion Exchange Chromatography coupled with Pulse Amperometric Detection (HPAEC-PAD) on a Thermofisher-Dionex ICS 5000 chromatographic system. The separation was achieved on a Thermofisher Carbopac PA 100 column (250 mm x 2mm) at a temperature of 35°C. The mobile phase consisted of deionized sodium hydroxide at 160 mM (A) and sodium hydroxyl at 160 mM wit sodium acetate at IM (B). Injection volume was 5pl and flow rate was kept at 0.25ml / min for a total run time of 15 min. The gradient programme was the following: 0 min 100% (A); 0.010 min - 6min 100% (A); 6.10 min -10 min 0% (A); 10.01 min - 15 min 100% (A). Sugars were identified by comparing retention time with available standards. Quantification was performed with a standard curve constructed by analysing a dilution series (25, 12.5, 8.3, 6.25 and 5 time) of a stock solution containing 1000 parts per million (ppm) of glucose, 2500 ppm of fructose and 5000 ppm of saccharose of the different species.

[0202] Chain length distribution of inulin was measured using High Performance Anion Exchange Chromatography coupled with Pulse Amperometric Detection (HPAEC-PAD) on a Thermofisher- Dionex ICS 5000 chromatographic system. The separation was achieved on a Thermofisher Carbopac PA 100 column (250 mm x 2 mm) at a temperature of 35°C. The mobile phase consisted of deionized sodium hydroxyl at 160 mM (A) and sodium hydroxyl at 160 mM wit sodium acetate at IM (B). Injection volume was 5 pl and flow rate was kept at 0.25 ml / min for a total run time of 102 min. The gradient programme was the following: 0 min 100% (A); 0 min - 75 min 55% (A); 75 min -85 min 55% (A); 85.1 min - 93 min 100% (A).

[0203] Samples were diluted to 0.8 g per 100 g and filtered on a 0.2 pm membrane prior to injection. The chain length distribution was expressed as a percentage of a given chain length and was obtained as the ratio of the peak area for a given chain length to the total peak area.

[0204] The anion exchange process, spanning from 0% to 44% of anionic exchange cycle duration, resulted in elevated monovalent content due to divalent anion and conjugated base of organic acid substitution in chloride. As the anionic resin saturation gradually diminished exchange efficiency, increase in divalent ions and organic acid concentration start to occur concurrently with a decrease in monovalent species. After 78% of the anion exchange cycle duration, there is no more impact of the ion exchange treatment on the juice composition. The sugar composition of the juice does not seem to be affected by the ion exchange treatment.

[0205] 2. Ion, sugar and protein removal with nanofiltration.

[0206] Next, different samples of the treated liquid taken at different times during the cycle (Figure 1) as well as a representative sample of the treated liquid collected throughout the full cycle, were then subjected to nanofiltration.

[0207] For the nanofiltration Applexion NFNOI07 membrane filtration multifunctional pilot plan was used. The nanofiltration membrane was used during nanofiltration was a spiral module with a molecular weight cutoff of 150 / 300 Da and an MgSO4selectivity of 96%. This membrane can operate at a maximum temperature of 60°C, a pressure of up to 55 bar, and a pH range between 3 and 9.

[0208] 200 liters of different samples of treated liquid with 10 g of carbohydrates / 100 g of deionized liquid were transferred to the 1000-liter thermostatic tank and heated to 85°C after stirring. Concurrently, another tank was filled with room temperature demineralized water intended for diafiltration. Following heating, the juice was cooled to match the operational temperature of the membrane. Subsequently, a water point test was conducted using the tank currently positioned on the pilot system, measuring the permeate flow rate in recycling mode at a loop temperature of 25°C and an inlet pressure of 10 bars. Upon completion, the drains of the pilot system were opened to drain the accumulated deionized water before proceeding to the subsequent phases. The filtration process then commenced in recycling mode to mix the treated liquid with the water present in the dead volume of the nanofiltration apparatus and stabilize parameters. Nanofiltration treatment was performed at a transmembrane pressure of 10 bars and a temperature of 55°C, in accordance with the manufacturer's (Applexion) guidelines. Once parameters were stable, the peristaltic pump was calibrated based on the obtained permeate flow rate to maintain a consistent volume in the feed tank, with demineralized water introduced as needed to compensate permeate loss. The collected permeate was directed to an independent tank equipped with a scale, while the retentate was recycled back into the feed tank, and regular samples were extracted for subsequent analysis at intervals of 0.5 VolumeWater / Volume retentate (Vwater / Vretentate).

[0209] Figure 2 illustrates the membrane's efficient removal of ions during different steps of diafiltration. Regardless of the type of juice, following diafiltration, there was a notable reduction in ionic load of over 40% of in the filtered liquid after 4 stages of diafiltration. The more the sample treated by nanofiltration was taken far in the anion exchange cycle progresses, the higher the residual load in milliequivalents was. Indeed, the removal rate of ion was higher in a juice taken at the beginning of the anion cycle (i.e. before 25% of the total anion cycle) with only 12% of milliequivalent left after nanofiltration, than in a juice taken later in the anion cycle, where up to 26% of milliequivalent are still present there after treatment. This can be explained by the initial juice composition, as the first treated sample contains significantly more monovalent ions that go more easily through the membrane than divalent ions and organic acid and their conjugated bases.

[0210] The total ionic load of the liquid was calculated as the sum of the ionic loads of each of the ions. The reduction of the ionic load after ion exchange treatment can be calculated as:

[0211] , . , total ionic load after to ion exchange — total ionic load prior to ion exchange > reduction or the ionic load = - total ionic load prior to ion exchange x 100

[0212] The reduction of the ionic load after ion exchange treatment was 56.46%.

[0213] Regarding desugarization (removal of fructose and glucose), it was observed during diafiltration that between 30% and 50% of sugars (fructose and glucose) are removed in the permeate (Figure 3 and 5A). No significant difference in sugar reduction of the filtered liquid based on the stage (i.e. % of the cycle) of the anion exchange / cation exchange cycle was observed. Thus, a balance between achieving high demineralization rates and maintaining acceptable desugarization rates must be struck. After a Vwater / Vretentate of 4, a notable decrease of 25% ± 5% in protein content is noted (Figure 5B). This reduction holds significance since proteins are charged molecules that require removal during demineralization. A lower protein concentration could consequently also alleviate the workload of subsequent demineralization and polishing processes downstream.

[0214] It appears that the nanofiltration performance is equivalent in terms of desugarization (e.g. the removal of glucose and fructose) and reduction of protein content. The most significant difference was observed in demineralization performance. Furthermore, only 2 or 2.5 diafiltration steps seem necessary to achieve satisfactory results that would eliminate or alleviate the demineralization step. To assess whether nanofiltration can more effectively remove ions of the same species, such as monovalent ions, a liquid comprising inulin was subjected to nanofiltration, and the ionic load of the composition was measured as described previously. Additionally, the liquid comprising inulin underwent ion exchange treatment, where cations were exchanged for monovalent cations, in this case sodium, and anions were exchanged for monovalent anions, in this case chloride. The treated liquid was then subjected to nanofiltration. As shown in Figure 4, nanofiltration demonstrated improved ion removal when the liquid was first subjected to ion exchange.

[0215] 3. Reverse osmosis (optional)

[0216] Since nanofiltration, especially diafiltration, consumes significant amounts of water, there is interest in reusing liquid fractions within the system and method. Therefore, tests were conducted to determine if both water and salts from the nanofiltration permeate fraction can be recycled through reverse osmosis treatment. All the liquid fractions utilized in nanofiltration eventually reaches the nanofiltration permeate fraction. Reverse osmosis (RO), a pressure-driven membrane process akin to nanofiltration, effectively separates ions from water, potentially enabling the recycling of both water and salts. This process concentrates salts in the RO retentate fraction while producing an RO permeate fraction with a composition akin to demineralized water. The brine obtained in the RO retentate fraction, rich in NaCI, may serve for regenerating anion exchange resins, while the RO permeate fraction can be utilized during nanofiltration, preferably as diafiltration water during the diafiltration steps.

[0217] Method: A portion of the nanofiltration permeate fraction is directed to feed a reverse osmosis membrane in the pilot unit, operating in concentration mode.

[0218] The RO permeate flow rates observed were approximately 30 litres (l) / hours (h) / meters2(m2), closely aligned with the manufacturer's recommended maximum flow rate. In initial tests, the liquid comprising inulin was concentrated up to 8 times, leading to a remarkable 87% water recycling during diafiltration. However, the maximum achievable concentration rate was limited by the dead volume of the pilot unit. Despite operating pressures remaining below 15 bars, reverse osmosis installations can function at pressures up to 40 bars. Hence, increasing pressure could enhance permeate flow rates further, achieving higher recycling rates.

[0219] The composition of the reverse osmosis permeate fraction closely resembles that of the demineralized water. While the reverse osmosis permeate fraction exhibit slightly higher sugar and chloride concentrations, these levels are sufficiently low to be inconsequential. Thus, the water produced meets the requisite quality standards for use at each stage of nanofiltration.

[0220] Quality of Reverse Osmosis Retentate: Nanofiltration permeate fraction from the initial and final stages of the anion exchange cycle were treated via reverse osmosis. The resulting composition of the RO retentate fraction after RO treatment primarily comprises chloride and potassium (Figure 7). The retentate can be used in ion exchanger regeneration.

Claims

37CLAIMS1. A method for purifying a liquid comprising inulin comprising the steps of:(a) providing a liquid comprising: inulin, anions and cations;(b) subjecting the liquid of a) to one or more ion-exchange treatment(s) with one or more ion exchanger(s), wherein the anions in said liquid are exchanged for a single monovalent anion and wherein the cations in said liquid are exchanged for a single monovalent cation;(c) subjecting the treated liquid of b) to at least one nanofiltration treatment to obtain a nanofiltration retentate fraction comprising purified inulin and a nanofiltration permeate fraction.

2. The method according to claim 1, wherein said nanofiltration treatment comprising at least one diafiltration step.

3. The method according to claim 1 or 2, wherein said nanofiltration treatment comprising at least one concentration step.

4. The method according to claim 1 to 3, wherein said nanofiltration treatment comprising at least one concentration step and at least one diafiltration step.

5. The method according to claim 1 to 4, wherein said nanofiltration permeate fraction is subjected to one or more water purification process(es).

6. The method according to claim 5, wherein the water purification process is a reverse osmosis treatment to obtain a reverse osmosis retentate fraction and a reverse osmosis permeate fraction.

7. The method according to claim 6, wherein at least part of the reverse osmosis retentate fraction is used to regenerate the one or more ion exchanger.

8. The method according to any one of claims 6 or 7 , wherein at least part of the reverse osmosis permeate fraction is used during the nanofiltration treatment.

9. The method according to claim 8, wherein the nanofiltration treatment comprises at least one diafiltration step in which at least part of the reverse osmosis permeate fraction is used.

10. The method according to any one of claims 1 to 9, wherein the nanofiltration treatment comprises at least two subsequent diafiltration steps.

11. The method according to any one of claims 1 to 10, wherein in the nanofiltration treatment, a transmembrane pressure of at least 10 bars is applied.3812. The method according to any one of claims 1 to 11, wherein the nanofiltration treatment is performed at a pH between 3 and 9.

13. The method according to any one of claims 1 to 12, wherein the ion-exchanger comprises an anion exchange resin and cation exchange resin containing the single species of monovalent cation and the single species of monovalent anion to generate a treated liquid comprising the single species of monovalent cations and the single species of monovalent anion.

14. The method according to any one of claims 1 to 13, wherein after the nanofiltration treatment the nanofiltration permeate fraction is subjected to a demineralisation step to remove the single species of monovalent cation and the single species monovalent anions.

15. The method according to any one of claims 1 to 14, wherein the single species monovalent cation comprises sodium and / or potassium ions and the single species monovalent anions comprise chloride ions.

16. The method according to any one of claims 1 to 15, wherein prior to step c) and after step b) the liquid is heated to about 110 degrees Celsius and subsequently cooled to at most about 65 degrees Celsius prior to nanofiltration.

17. The method according to any one of claims 1 to 16, wherein at least 50 % of the ionic load (expressed in milliequivalent (mEq) / (kg dry matter)) of the liquid after ion exchange treatment is in the form of monovalent anions and monovalent cations, preferably sodium and / or potassium ions and chloride ions.

18. A system for purifying a liquid comprising inulin with a method according to any one of claims1 to 17, wherein the system comprises an ion-exchanger for exchanging anions and cations in the liquid comprising inulin for monovalent cations and anions, the ion-exchanger being connected to a nanofiltration apparatus for filtering the liquid comprising inulin, monovalent cations and anions.

19. The system according to claim 18, further comprising a reverse osmosis means which is connected to the nanofiltration means and / or connected to the ion-exchanger.

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