The present invention relates to methods for the separation and fractionation of lipid materials, in particular fatty acids and fatty acid esters, according to their degree of unsaturation. more specifically, the invention concerns solvent-free processes in which lipid blends are frozen into rigid bodies and subjected to centrifugal forces to expel unfrozen fractions

Abstract

The invention is related to a process for separating lipids of differing degrees of unsaturation, comprising forming crystals in a lipid blend and separating liquid and solid fractions by a separation step The lipid blend is first cooled to a temperature below the crystallisation temperature of at least one higher-melting component to obtain a rigid solid lipid matrix, and the rigid solid lipid matrix is then subjected to centrifugal forces of at least 500g (RCF) to expel a liquid fraction enriched in lower-melting, more unsaturated lipids, the separation being carried out in the substantial absence of added solvent.

Description

[0001] The present invention relates to methods for the separation and fractionation of lipid materials, in particular fatty acids and fatty acid esters, according to their degree of unsaturation. More specifically, the invention concerns solvent-free processes in which lipid blends are frozen into rigid bodies and subjected to centrifugal forces to expel unfrozen fractions.

[0002] BACKGROUND

[0003] The present invention relates to methods for the separation and fractionation of lipid materials, in particular fatty acids and fatty acid esters, according to their degree of unsaturation. More specifically, the invention concerns solvent-free processes in which lipid blends are frozen into rigid bodies and subjected to centrifugal forces to expel unfrozen fractions.

[0004] Fractionation of fatty acids, fatty acid esters, and triglyceride oils is a well-established industrial practice, with applications in food technology, nutraceuticals, oleochemicals, and biofuels. Conventional separation technologies rely primarily on crystallisation followed by filtration or centrifugation of a slurry.

[0005] Dry fractionation processes are described, for example, in US 5,959,129 (Unilever), in which a lipid melt is cooled under controlled conditions to form a crystal slurry that is subsequently separated by filtration. Such processes are limited in efficiency, typically achieving only 50- 60% purity of the desired fraction without the addition of solvents.

[0006] Other references, such as EP 2 657 327 (Fuji Oil), disclose the use of filtration aids in combination with crystallisation, again requiring slurry handling and filter-press separation. High-purity separations are achieved by solvent fractionation, wherein lipid mixtures are cooled in the presence of solvents such as acetone, ethanol, or hexane, as described in, for example, EP 0 798 369 and US 6,069,263. However, solvent use increases processing cost and complexity, introduces regulatory burdens, and requires energy -intensive solvent recovery and removal steps.

[0007] In the field of centrifugation, numerous designs for solid-liquid separation are known. These include peeler centrifuges, basket centrifuges, and decanter centrifuges. Such systems are configured to operate on liquid suspensions or slurries, continuously feeding material into the centrifuge and discharging liquid through perforated walls while retaining a growing cake of solids. Representative examples include designs disclosed in US 7,258,846 (Alfa Laval). However, no prior art teaches or suggests using a rigid frozen lipid body as the matrix for centrifugal expression.

[0008] Accordingly, the known prior art is characterised by several shortcomings. Current processes depend on slurry feeding for both filtration and centrifugation. Dry fractionation methods are limited in efficiency unless solvents are introduced. Solvent fractionation, while effective, entails cost, safety, and environmental disadvantages. Conventional centrifuges are optimised for slurry feeds and offer no teaching of applying centrifugal forces directly to frozen lipid masses.

[0009] It is therefore an objective of the present invention to provide a process for separating lipids of differing degrees of unsaturation that does not require the use of solvents. It is another objective of the invention to enable separation using a rigid frozen lipid body as the matrix for centrifugal expression, rather than relying on slurry-based feeds.

[0010] A further objective of the invention is to improve separation efficiency and purity, particularly in the enrichment of saturated and unsaturated fatty acid esters, compared with conventional dry fractionation methods.

[0011] Still another objective of the invention is to provide alternative embodiments of the process, including the use of prefabricated frozen cylinders, frozen pellets, or in-situ freezing within the centrifuge itself.

[0012] It is also an objective of the invention to offer a scalable, industrially applicable process suitable for the production of food-grade lipids, nutraceuticals, oleochemicals, and biofuels, while reducing energy and solvent consumption.

[0013] SUMMARY OF THE INVENTION

[0014] The present invention is related at a process for separating lipids of differing degrees of unsaturation, comprising forming crystals in a lipid blend and separating liquid and solid fractions by a separation step. The lipid blend is first cooled to a temperature below the crystallisation temperature of at least one higher-melting component to obtain a rigid solid lipid matrix, and the rigid solid lipid matrix is then subjected to centrifugal forces of at least 500 g, relative centrifugal force (RCF, multiples of gravity) to expel a liquid fraction enriched in lower-melting, more unsaturated lipids, the separation being carried out in the substantial absence of added solvent.

[0015] As used herein, the term “lipid blend” refers to a mixture comprising two or more lipid components, including but not limited to fatty acids, fatty acid esters (such as methyl or ethyl esters), triglycerides, phospholipids, or combinations thereof. The lipid blend may originate from natural sources such as fish, microalgae, krill, copepods, or vegetable oils, or may be synthetically prepared.

[0016] The term “crystallisation temperature” refers to the temperature at which a given lipid component transitions from the liquid phase to the solid crystalline phase under defined cooling conditions. This temperature varies with chain length, degree of unsaturation, and the presence of other lipids in the blend. For the purposes of the invention, cooling to “below the crystallisation temperature” means cooling sufficiently to produce a solid phase of the higher- melting lipid component.

[0017] The term “rigid solid lipid matrix” refers to the mechanically stable solid structure obtained when a lipid blend is cooled to a temperature sufficiently below the crystallisation temperature of at least one higher-melting component. The rigid matrix differs from a slurry of crystals dispersed in liquid oil, in that the mass is consolidated, firm, and able to withstand centrifugal forces without disintegration.

[0018] The term “centrifugal forces” refers to the relative centrifugal force (RCF) exerted on the frozen lipid matrix when rotated in a centrifuge, expressed in multiples of Earth’s gravitational acceleration (g). Centrifugal forces of at least 500 g are required to effect separation in the present invention, with preferred ranges between 1000 g and 10,000 g depending on the lipid blend and apparatus design.

[0019] The term “added solvent” refers to any organic or inorganic solvent intentionally introduced into the lipid blend to facilitate crystallisation, solubilisation, or separation. Examples include acetone, ethanol, hexane, and similar agents commonly used in solvent fractionation processes. In the context of the present invention, the process is carried out in the substantial absence of added solvent, meaning that no solvent is intentionally introduced to aid the separation, though trace residuals or wash steps may optionally be employed.

[0020] The present invention is directed to a process for separating lipids of differing degrees of unsaturation, comprising the formation of crystals in a lipid blend and the subsequent separation of liquid and solid fractions by a centrifugal separation step.

[0021] In accordance with the invention, a lipid blend comprising fatty acids, fatty acid esters, or mixtures thereof is first cooled to a temperature below the crystallisation temperature of at least one higher-melting component. Cooling to this degree produces a rigid solid lipid matrix, as opposed to a fluid slurry. The rigid structure is mechanically stable and capable of withstanding the centrifugal forces applied in the subsequent processing step.

[0022] The rigid solid lipid matrix is then subjected to centrifugal forces of at least 500 g, preferably between 1000 g and 10,000 g, measured as relative centrifugal force (RCF, multiples of Earth’s gravity). Under the influence of these high forces, unfrozen lipid fractions are expressed from the solid matrix. These expelled fractions are enriched in lower-melting, more unsaturated lipid components, while the retained matrix is correspondingly enriched in higher-melting, more saturated lipid components.

[0023] The separation process of the invention is carried out in the substantial absence of added solvent. This feature distinguishes the invention from conventional solvent fractionation processes, thereby eliminating the need for solvent addition, recovery, and removal. The process also differs fundamentally from conventional dry fractionation, which relies on forming a crystal slurry that must be filtered or pressed, often with limited efficiency. By contrast, the invention achieves efficient and selective separation directly from a rigid frozen lipid body without slurry handling.

[0024] The invention thus provides an improved process for lipid fractionation that is efficient, scalable, and environmentally advantageous, enabling the production of high -purity lipid fractions suitable for use in foods, nutraceuticals, pharmaceuticals, cosmetics, oleochemicals, and biofuels.

[0025] In some embodiments, the lipid blend may be cooled to a temperature substantially below the crystallisation temperature of the higher-melting lipid component. The cooling may be carried out to at least 10 °C below the crystallisation point, and in preferred forms to -10 °C or lower, more preferably to around -25 °C and most preferably to around -35 °C. At these temperatures, the higher-melting lipid fraction may form a rigid crystalline body with mechanical strength sufficient to endure centrifugal forces. The rigidity of the frozen structure may ensure that lower-melting lipid components remain mobile and can be expressed under centrifugal stress. Small amounts of a solvent may also be added to the blend before it is frozen. In some embodiments, a solvent may be added to the lipid blend prior to the freezing step. The solvent addition may facilitate more uniform solidification of the higher-melting lipid components and improve the subsequent expulsion of the lower-melting fraction during centrifugation. The amount of solvent added can vary depending on the composition of the lipid blend and the desired degree of separation. Typically, the solvent may constitute up to about 30% by weight of the total mixture. In preferred embodiments, the solvent content is about 10% by weight, and in most preferred embodiments, about 5% by weight. By limiting the solvent content to relatively small amounts, the process maintains the advantages of a substantially solvent-free separation, while still providing improved crystallisation kinetics and separation efficiency. Suitable solvents may include alcohols such as ethanol, isopropanol, butanol or glycerol; alkanes such as hexane or heptane; ketones such as acetone; esters such as methyl acetate or ethyl acetate; and terpenes such as limonene.

[0026] In certain embodiments, the frozen lipid mass may be prepared in the form of discrete units such as pellets, blocks, or cylinders that are introduced into the centrifuge prior to operation. These units may be manufactured by extrusion and cutting, by casting into molds, or by plate freezing followed by sectioning. Providing the lipid feed in pre-formed solid units may enable efficient handling, controlled dosing into the centrifuge, and flexibility in scaling the process.

[0027] In another embodiment, the frozen lipid mass may be shaped as a prefabricated cylinder dimensioned to fit within the bowl of a centrifuge, such as a peeler centrifuge. The prefabricated cylinder may have a slightly conical geometry to facilitate insertion and removal from the centrifuge bowl. Alternatively, the cylinder may include a central bore extending along its axis, thereby increasing internal surface area and facilitating the release of unfrozen liquid fractions during centrifugation. Such design modifications may improve both handling and separation efficiency.

[0028] In further embodiments, the prefabricated frozen lipid body may be formed with a hexagonal cross-sectional shape. A hexagonal geometry may provide several practical advantages, including easier stacking and storage of multiple cylinders in large quantities, as well as simplified handling and automated feeding into the centrifuge apparatus. The hexagonal profile also facilitates efficient use of space during production, transport, and storage of frozen lipid units.

[0029] In one embodiment, the centrifuge bowl may be dimensioned to accept a prefabricated frozen lipid cylinder having either a hexagonal, conical, or cylindrical geometry, optionally with a central bore.

[0030] In further embodiments, the rigid lipid mass may be formed directly within the centrifuge bowl by introducing the lipid blend in liquid form and rapidly cooling it in situ. Cooling may be accomplished by introducing a cryogenic medium such as liquid nitrogen or carbon dioxide into the centrifuge chamber. The rapid freezing provided by such media may ensure that the lipid blend solidifies into a rigid matrix suitable for immediate centrifugation. This approach may eliminate the need to transport or load prefabricated frozen lipid blocks, enabling continuous operation.

[0031] In some embodiments, the rigid lipid mass may be subjected to centrifugal forces in the range of 500 g to 10,000 g relative centrifugal force (RCF), with preferred values between 1,000 g and 5,000 g. Applying centrifugal forces within this range may be sufficient to expel the lower-melting, more unsaturated lipid fraction from the solid matrix, while retaining the higher-melting saturated fraction in the solid cake. Lower forces may result in incomplete expulsion of the liquid fraction, whereas higher forces within the stated range may provide more efficient separation without compromising the structural integrity of the frozen lipid matrix.

[0032] In another embodiment, the solid lipid cake obtained after centrifugation may optionally be subjected to a washing step using a small volume of solvent to increase purity. Suitable solvents may include alcohols such as ethanol, isopropanol, butanol or glycerol; alkanes such as hexane or heptane; ketones such as acetone; esters such as methyl acetate or ethyl acetate; and terpenes such as limonene. Such a solvent wash may remove residual unfrozen lipid entrapped within the solid matrix, thereby yielding a higher-purity saturated fraction.

[0033] In additional embodiments, the lipid blend may be derived from natural marine or biological sources rich in polyunsaturated fatty acids, such as fish oils, algal oils, krill oils, copepod oils, or lipids from fish roe. These feedstocks may be particularly suitable for nutraceutical and pharmaceutical uses because of their high omega-3 fatty acid content.

[0034] The process may be applied to the preparation of a wide range of products, including active pharmaceutical ingredients, dietary supplements, animal feed ingredients, cosmetic formulations, oleochemical intermediates, and biodiesel. The versatility of the method may make it suitable for both food-grade and industrial applications where purity and sustainability are critical.

[0035] In yet another embodiment, the process may be employed to enrich the unsaturated fatty acid ester fraction of a lipid blend prior to further concentration steps such as distillation or rectification. By first removing higher-melting saturated esters, the efficiency of subsequent enrichment steps may be improved, enabling more effective production of concentrated omega-3 fatty acid esters. This preparatory separation step may provide a cleaner feedstock, reduce energy demand, and improve overall yield.

[0036] In some embodiments, the present invention may also relate to a centrifugal apparatus that is specifically adapted for the separation of lipids using a rigid solid lipid matrix as the feed material. Conventional centrifuges are typically designed to process liquid suspensions or slurries. By contrast, the present apparatus may be configured to accommodate prefabricated or in-situ formed frozen lipid bodies, and to enable efficient expression of liquid fractions therefrom under high centrifugal force.

[0037] The centrifugal apparatus may comprise a centrifuge bowl designed to receive a rigid frozen lipid matrix. The bowl may be cylindrical or slightly conical in shape and may optionally include a removable or adjustable flange to facilitate placement and removal of prefabricated frozen cylinders. The inner surface of the bowl may be perforated or include drainage channels to allow expelled liquid fractions to pass outward while retaining the solid cake.

[0038] In one embodiment, the centrifuge bowl may be dimensioned to accept a prefabricated frozen lipid cylinder having either a hexagonal, conical, or cylindrical geometry, optionally with a central bore. The apparatus may include guides or supports to ensure proper seating of the frozen cylinder within the bowl during loading. A sealing mechanism may be provided to secure the frozen body against the bowl walls and to prevent vibration or imbalance during rotation.

[0039] In some embodiments, the centrifugal apparatus may comprise a centrifugal bowl having an oval or elliptical inner body with a relatively smaller opening for the introduction of the rigid solid lipid matrix. In this configuration, the rigid solid lipid matrix may be introduced through the opening into the oval drum. When the centrifuge is operated, the high centrifugal forces may cause the rigid solid lipid matrix to deform slightly and adapt to the oval shape of the drum body. The geometric adaptation of the frozen lipid body to the oval interior may result in secure retention of the mass during operation, as the adapted body becomes larger than the opening through which it was introduced. In this way, the rigid solid lipid matrix may be held firmly inside the drum even under high centrifugal forces, without the need for mechanical fasteners or additional retaining structures. Following completion of the centrifugation step, when the drum is stopped and the forces removed, the solid cake may elastically return toward its original shape. This shape recovery may allow the solid cake body to be withdrawn through the smaller opening of the drum. The oval drum design therefore provides a simple but effective means of retaining the frozen lipid body during centrifugation while still permitting convenient removal after processing.

[0040] This embodiment may be applied both to prefabricated lipid cylinders and to in-situ formed frozen lipid bodies, offering a versatile design option that enhances both operational safety and ease of handling.

[0041] In another embodiment, the centrifugal apparatus may be equipped with a hopper feed system configured to introduce frozen lipid pellets or blocks into the bowl. The hopper may deliver the frozen units either batchwise or continuously, enabling flexible operation. The design may include baffles or distributors to spread the pellets evenly within the bowl before centrifugation.

[0042] As used herein, the term “hopper feed system” refers to a device configured to store and deliver solid feed material, typically in the form of pellets, granules, or blocks, into a processing unit under controlled conditions. The hopper may be of funnel-shaped, conical, or rectangular design and may rely on gravity, vibration, auger mechanisms, or other means to introduce the solid material into the centrifuge bowl. In the context of the present invention, the hopper feed system is adapted to deliver pre-frozen lipid pellets or blocks into the centrifuge prior to or during centrifugation.

[0043] In further embodiments, the apparatus may be adapted for in-situ freezing of the lipid blend inside the bowl. The apparatus may comprise one or more spray nozzles for introducing liquid lipid into the rotating bowl. A cryogenic medium inlet may be provided, allowing injection of liquid nitrogen or carbon dioxide into the chamber to achieve rapid freezing of the sprayed lipid droplets. The frozen lipid particles thus formed may consolidate into a rigid matrix suitable for immediate centrifugation without prior handling or prefabrication.

[0044] The centrifugal apparatus may be driven by a central drive shaft, dimensioned to provide rotational speeds corresponding to centrifugal forces between 500 g and 10,000 g, preferably 1,000 g to 5,000 g. The drive shaft and bearings may be reinforced to withstand the additional stresses associated with spinning rigid frozen lipid bodies, as opposed to fluid slurries. In some embodiments, the apparatus may further comprise an outlet system for collecting the expelled liquid fraction. This may include channels, perforations, or drains at the periphery of the bowl, connected to a discharge conduit. A separate discharge mechanism may be provided for the retained solid cake, such as a peeler blade, scraper, or removable liner.

[0045] Optionally, the apparatus may include a solvent wash system, configured to introduce a small volume of solvent through spray nozzles or wash rings after the primary centrifugation step. This wash may remove residual liquid trapped in the solid cake, with the solvent and expelled lipids collected through the same outlet system.

[0046] The design of the centrifugal apparatus may also include temperature control features, such as insulated bowl walls, cryogenic jackets, or controlled heating / cooling elements, enabling precise management of freezing and separation conditions.

[0047] Accordingly, this centrifugal apparatus is adapted specifically for use with a rigid solid lipid matrix, providing structural modifications and additional features that distinguish it from conventional centrifuges intended for liquid-solid slurry separations.

[0048] FIGURES

[0049] Figure 1 illustrates a process for separating lipids of differing degrees of unsaturation. The process comprises cooling a lipid blend to form crystals of higher-melting components and subjecting the rigid solid lipid matrix to centrifugal forces, thereby separating liquid and solid fractions.

[0050] Figure 2 illustrates a centrifuge apparatus comprising a centrifuge bowl with a top opening for receiving a rigid solid lipid matrix in the form of pre-frozen pellets, granules, or blocks. The pellets, granules, or blocks are introduced into the bowl prior to centrifugation.

[0051] Figure 3 illustrates a centrifuge apparatus comprising a centrifuge bowl with a top opening for receiving a rigid solid lipid matrix in the form of a prefabricated cylinder. The cylinder may be dimensioned to fit the inner geometry of the centrifuge bowl.

[0052] Figure 4 illustrates a centrifuge apparatus comprising a centrifuge bowl in which the rigid solid lipid matrix is formed in situ. A liquid lipid blend is introduced into the bowl and cooled using a cryogenic medium, such as liquid nitrogen or carbon dioxide, to produce the rigid solid lipid matrix prior to centrifugation.

[0053] Figure 5 illustrates a centrifuge apparatus comprising an oval-shaped centrifuge bowl. A rigid solid lipid matrix formed as a cylinder is placed into the bowl. During centrifugation, the rigid solid lipid matrix adapts to the oval shape of the centrifuge bowl, thereby being retained within the bowl during application of high centrifugal forces.

[0054] Figure 6 illustrates the relationship between temperature of a lipid blend and the relative content of a high-melting component remaining in the liquid phase after separation, DETAILED DESCRIPTION OF THE FIGURES

[0055] In the following, embodiments of the invention will be discussed in detail with reference to the appended figures. It should be understood, however, that the figures are not intended to limit the invention to the subject-matter depicted in the figures.

[0056] Fig. 1 illustrates a schematic process flow for the separation of lipids of differing degrees of unsaturation according to the present invention.

[0057] A lipid blend, comprising fatty acids, fatty acid esters, or mixtures thereof, serves as the starting material. This lipid blend is introduced into a cooling / freezing unit, where the temperature is reduced to a value below the crystallisation point of at least one higher-melting lipid component. Cooling under these conditions results in the solidification of the higher- melting component and the formation of a rigid lipid mass or a rigid solid lipid matrix.

[0058] Unlike conventional processes, which require slurries or solvent-assisted crystallisation, the present method creates a mechanically stable solid matrix directly from the lipid blend.

[0059] The rigid lipid mass 11 is then subjected to a centrifugation step, in which the solid mass is exposed to centrifugal forces sufficient to expel entrapped liquid fractions. During this operation, the more unsaturated and lower-melting lipids are expressed from the solid matrix, forming an expelled liquid fraction 12. At the same time, the higher-melting saturated lipid component remains in the centrifuged body, resulting in a solid cake 16 that is enriched in said component.

[0060] Accordingly, the process depicted in Fig. 1 demonstrates the central concept of the invention: separation of lipid components by freezing the blend to a rigid mass 11 and centrifuging it to obtain two distinct outputs, namely a purified liquid fraction 12 and a complementary solid cake 16.

[0061] Figure 2 illustrates a pellets, granules, or blocks-feeding embodiment of a centrifuge apparatus 20 suitable for performing the process of the invention. The apparatus comprises a centrifuge bowl 22, within which separation of solid and liquid lipid fractions takes place.

[0062] In this embodiment, the lipid blend is first frozen into discrete frozen lipid pellets, granules, or blocks 13. These pellets, granules, or blocks 13 are introduced into the centrifuge bowl 22 through a hopper feed system that permits controlled delivery of the pre-frozen material during centrifuge operation. Feeding the lipid material in pellets, granules, or blocks form 13 simplifies handling and enables continuous or semi-continuous operation of the separation process.

[0063] When the centrifuge apparatus 20 is rotated, centrifugal forces act upon the frozen lipid pellets, granules, or blocks 13. The higher-melting components within the pellets, granules, or blocks 13 consolidate to form a rigid solid cake 16, while the lower-melting and more unsaturated components are expelled radially outward. The expelled liquid fraction 12 may be discharged through an outlet to a collection chamber 26 outside the bowl 22.

[0064] Accordingly, Figure 2 demonstrates an embodiment of the invention wherein pre-frozen lipid material in pellets, granules, or blocks 13 form is processed in a centrifuge. This configuration provides operational flexibility for bulk lipid blends and allows for efficient solid-liquid separation under high centrifugal force without the addition of solvent.

[0065] Figure 3 illustrates an embodiment of a centrifuge apparatus 20 for separating lipid fractions according to the invention. The apparatus comprises a centrifuge bowl 22 into which a prefrozen lipid cylinder 15 is introduced through the opening 14 of the centrifuge bowl 22. The lipid cylinder 15 is a rigid lipid mass obtained by cooling a lipid blend to a temperature below the crystallisation temperature of the higher-melting lipid component, thereby providing a mechanically stable body capable of withstanding high centrifugal forces.

[0066] When the centrifuge apparatus 20 is operated, the pre-frozen lipid cylinder 15 is subjected to centrifugal forces through the rotation of the drive shaft. Under these conditions, the lower- melting and more unsaturated lipid components that remain unfrozen within the solid matrix are expelled radially outward. This expelled material accumulates along the periphery 27 of the centrifuge bowl 22 as the expelled liquid fraction 12, and / or it may be discharged through an outlet to a collection chamber outside the bowl 26. The higher-melting lipid components retained in the rigid structure remain as a solid cake 16, enriched in saturated components.

[0067] Accordingly, Figure 3 demonstrates the central inventive principle in which a pre-formed rigid lipid matrix functions as the separation medium itself. The use of a pre-frozen lipid cylinder 15 eliminates the need for slurry -based feeds or solvent-assisted crystallisation, thereby enabling efficient fractionation of lipid blends under high centrifugal force.

[0068] Figure 4 illustrates an embodiment of a centrifuge apparatus 20 in which lipid freezing and separation are carried out directly within the centrifuge. The apparatus 20 includes a centrifuge bowl 22 mounted on a drive shaft, which provides the rotational force necessary to generate high centrifugal fields.

[0069] In this embodiment, a liquid lipid feed is introduced into the bowl 22 through a spray nozzle 24. Simultaneously, a cooling medium inlet 25 supplies a cryogenic cooling agent, such as liquid nitrogen (LN2) or carbon dioxide (CO2), into the centrifuge interior. The atomisation of the liquid lipid by the spray nozzle 24, in combination with the rapid cooling provided by the cryogenic medium from the inlet 25, results in the in-situ formation of frozen lipid particles within the centrifuge bowl 22.

[0070] During centrifugation, the frozen lipid particles coalesce into a rigid lipid matrix 11. Under the applied centrifugal forces, the lower-melting and more unsaturated lipid components present within the mass are expelled radially outward and collected as the expelled liquid fraction 12 at the periphery 27 of the centrifuge bowl 22 and / or discharged through an outlet to a collection chamber 26 outside the bowl 22. The higher-melting lipid components remain in the central region, forming a solid lipid cake 16.

[0071] Accordingly, Figure 4 demonstrates an in-situ freezing embodiment in which the lipid blend is solidified directly within the centrifuge, eliminating the need for external pre-freezing and enabling continuous operation with direct feed of both liquid lipid and cryogenic coolant.

[0072] Figure 5 illustrates alternative embodiments of prefabricated lipid cylinders designed for insertion into a centrifuge bowl 22. These prefabricated bodies are formed by freezing a lipid blend into rigid cylindrical shapes prior to centrifugation, thereby enabling the frozen lipid itself to function as the separation matrix. In one embodiment, the centrifuge bowl 22 is provided with a slightly oval or elliptical inner shape. A prefabricated lipid cylinder is dimensioned such that it can be introduced through the opening 14 of the bowl 22. Once placed inside, the frozen cylinder conforms to the oval interior of the bowl 22 during centrifugation. This geometric adaptation secures the prefabricated body in position, ensuring that it is retained within the bowl 22 even under the action of high centrifugal forces.

[0073] When the centrifuge is operated, the higher-melting lipid components remain in the prefabricated body as a rigid solid cake 16. By contrast, the lower-melting and more unsaturated lipid components are forced radially outward through the rigid matrix and are collected at the periphery 27 of the centrifuge bowl 22, and / or discharged through an outlet to a collection chamber 26 outside the bowl 22. These expelled components may be discharged through an outlet configured for removal of the expelled liquid fraction 12.

[0074] After completion of the centrifugation process, the prefabricated body may return substantially to its original cylindrical shape. This elastic recovery allows the solid lipid cake 16 to be removed conveniently through the opening 14 of the centrifuge apparatus 20, without the need for disassembly of the bowl 22 or additional mechanical release systems.

[0075] Accordingly, Figure 5 demonstrates an embodiment in which the combination of a prefabricated rigid lipid cylinder 15 and an oval-shaped centrifuge bowl 22 provides an effective retention mechanism during centrifugation, while still enabling straightforward removal of the separated solid cake 16 once the operation is completed.

[0076] Figure 6 illustrates the relationship between temperature of a lipid blend and the relative content of a high-melting component remaining in the liquid phase after separation, thereby highlighting the advantages of the present invention over conventional crystallisation and filtration methods.

[0077] The x-axis represents the temperature (°C) of the lipid blend, ranging from approximately +30 °C to -30 °C. The y-axis indicates the relative content (%) of the high-melting lipid component present in the liquid fraction after attempted separation. The dotted curve depicts how the residual content of the high-melting component decreases as the blend is cooled.

[0078] At higher temperatures, above about +20 °C, the lipid blend exists in a fully liquid state, and no separation of components can be achieved. As the temperature is lowered into the intermediate region between +20 °C and -10 °C, the system comprises a liquid phase with dispersed crystals of the higher-melting component. In this region, conventional separation technologies such as filter presses or liquid-solid centrifuges may be applied. However, because the feed is still fluid, the separation is incomplete. At Point A (approx. -13 °C), which represents the lower operational temperature limit for such conventional technologies, the filtrate (olein fraction) still contains more than 10% of the high-melting component intended to be removed. Thus, conventional methods cannot achieve high-purity separation, even at their practical temperature limit.

[0079] By contrast, the present invention enables separation at much lower temperatures, where the lipid blend has already transitioned into a rigid solid matrix. At Point B (approximately -35 °C), the lipid mass is fully solidified, and centrifugation under high g-forces expels residual liquid trapped within the rigid solid lipid matrix. As shown in the figure, the relative content of the undesired high-melting component in the expelled liquid fraction approaches zero. This demonstrates that operating on a rigid solid lipid matrix rather than a viscous slurry enables far greater purity of separation and minimises contamination of the liquid fraction with high- melting lipids.

[0080] Accordingly, Figure 6 demonstrates the key technical advantage of the invention: whereas conventional crystallisation-based separations are limited by the need to process fluid systems at higher temperatures, the present process utilises solidified lipid matrices at much lower temperatures to achieve superior fractionation efficiency.

Claims

CLAIMS1. A process for separating lipids of differing degrees of unsaturation, comprising forming crystals in a lipid blend and separating liquid and solid fractions by a separation step, characterised in that the lipid blend is first cooled to a temperature below the crystallisation temperature of at least one higher-melting component to obtain a rigid solid lipid matrix (11), and the rigid solid lipid matrix (11) is then subjected to centrifugal forces of at least 500g (RCF) to expel a liquid fraction (12) enriched in lower-melting, more unsaturated lipids, the separation being carried out in the substantial absence of added solvent.

2. The process according to claim 1, wherein the lipid blend is cooled to at least 10 °C below the crystallisation temperature of the higher-melting component, preferably to < -10 °C, more preferably to < -25 °C, and most preferably to < -35 °C.

3. The process according to claim 1 or 2, wherein the rigid solid lipid matrix (11) is provided in the form of pellets (13), blocks (13), or cylinders (15) introduced into a centrifuge (22) prior to operation.

4. The process according to claim 3, wherein the rigid solid lipid matrix (11) is in the form of a prefabricated cylinder (15) having a conical shape or a central bore, dimensioned to fit a peeler centrifuge bowl (23).

5. The process according to any of claims 1 to 4, wherein the rigid solid lipid matrix (11) is formed in situ within the centrifuge (22) by cooling the lipid blend using a cryogenic medium selected from liquid nitrogen or carbon dioxide prior to centrifugation.

6. The process according to any of the preceding claims, wherein the centrifugal force applied is between 500 g (RCF) and 10,000 g (RCF), preferably 1,000 g to 5,000 g.

7. The process according to any of the preceding claims, wherein a solvent is added to the lipid blend prior to freezing, the solvent being present in an amount of up to about 30% by weight, preferably about 10% by weight, and most preferably about 5% by weight.

8. The process according to any of the preceding claims, wherein the retained solid cake (16) is optionally subjected to a solvent wash step to increase purity, the solvent being selected from alcohols, alkanes, ketones, esters, terpenes, or mixtures thereof.

9. The process according to any of the preceding claims, wherein the lipid blend comprises fatty acids or esters derived from fish, microalgae, krill, copepods, or fish roe.

10. The process according to any of the preceding claims, wherein the process is applied to the preparation of active pharmaceutical ingredients, food supplements, animal feed ingredients, cosmetics, oleochemical intermediates, or biodiesel.

11. The process according to any of the preceding claims, wherein the process is used to enrich unsaturated fatty acid esters prior to concentration of omega-3 fatty acid esters by distillation or rectification.

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