ES2753402T3 - Continuous process for the dry fractionation of glyceride oils - Google Patents

Abstract

A continuous dry fractionation process of a glyceride oil comprising at least 80% by weight of palm oil, said process comprising: (a) providing a liquid glyceride oil having a temperature that is at least 5 ° C higher than that of starting point of solidification (SOP) of glyceride oil, the SOP of glyceride oil being the minimum temperature at which glyceride oil has an N value of 0%; (b) pre-cooling the liquid glyceride oil at a cooling rate of at least 1ºC / min by passing the glyceride oil through a heat exchanger to reduce the temperature of the liquid glyceride oil to at least 5ºC at a temperature that it is not less than 10ºC below the SOP and not more than 5ºC above the SOP; (c) homogenizing the pre-cooled glyceride oil to produce a pre-nucleated glyceride oil by passing the pre-cooled glyceride oil through a homogenizer in which the temperature of the glyceride oil is maintained at a temperature within 1 ° C of the pre-nucleation temperature Tp for at least 0.5 hours, said Tp being 0.5-10 ° C below the SOP; (d) crystallize the pre-nucleated glyceride oil to produce a crystallized glyceride oil containing separable fat crystals by passing the pre-nucleated glyceride oil through one or more crystallizers to reduce the temperature of the pre-nucleated glyceride oil with at least 10 ° C at a crystallization temperature of Tc and maintaining the glyceride oil at a temperature within 1 ° C of Tc for at least 1 hour; and (e) removing separable fat crystals from the crystallized glyceride oil and recovering an olein fraction from the glyceride oil.

Description

DESCRIPTION

Continuous process for the dry fractionation of glyceride oils

Technical field of the invention

The present invention provides a continuous process for the dry fractionation of glyceride oils. More particularly, the present invention relates to a continuous dry fractionation process of a glyceride oil, said process comprising:

(a) providing a liquid glyceride oil;

(b) pre-cooling the liquid glyceride oil by passing the glyceride oil through a heat exchanger;

(c) homogenizing the pre-cooled glyceride oil to produce a pre-nucleated glyceride oil by passing the pre-cooled glyceride oil through a homogenizer;

(d) crystallizing the pre-nucleated glyceride oil to produce a crystallized glyceride oil containing separable fat crystals by passing the pre-nucleated glyceride oil through one or more crystallizers; and

(e) removing separable fat crystals from the crystallized glyceride oil and recovering an olein fraction from the glyceride oil, as further defined in claim 1.

The present description further relates to a system for continuous dry fractionation of glyceride oils, which is useful for understanding the invention without being part of it, comprising: a feeding container; a plate heat exchanger; a homogenizer; a sequence of at least 2 crystallizers; and a solid-liquid separator that has an input that is connected to the output of the last crystallizer.

Background of the Invention

Fractionation processes are essential for the modern edible oil and fat processing industry, especially for the palm oil processing industry. Starting from a glyceride oil with given melting characteristics, these processes allow the recovery of separate oil fractions with different melting profiles and different viscosities. Since a specific melting profile is needed depending on the oil application (eg, more liquid at room temperature for spreads, more solid at room temperature for margarines), fractionation opens up a greater variety of possibilities for oil application of initial glyceride, thus adding value to its use.

Fractionation implies the creation of circumstances that induce a partial (fractional) crystallization of the oil. A solid fraction (stearin) is formed which can then be separated from the remaining liquid phase (olein). Typically, the higher melting triglycerides contained in the oil will crystallize in the solid fraction and the lower melting triglycerides will remain in liquid form. Consequently, at a given temperature, the stearin fraction of the oil typically has a high solids content, while the olein fraction of the oil typically has a low solids content. As presented by R.E. Timms, 2005; the quality of the olein fraction depends only on the crystallization stage; while the quality of the stearin fraction depends on the stage of both crystallization and separation. The key challenge in fractionation is to use the crystallization and separation process conditions that allow high quality and performance of the olein and stearin fractions.

The three different fractionation systems available on an industrial scale differ in these conditions, which in turn causes them to differ in sophistication.

In detergent fractionation, a surfactant solution is used to transfer the crystallized material from the oil phase to an aqueous phase to facilitate subsequent separation (W. Hamm, 1995). 8-10 ppm of surfactant remains in the fractions (Bernadini, 1973). The yield of palm olein from detergent fractionation is normally approximately 80% at iodine levels of 52, 57, and 30 for crude palm oil, palm olein, and palm stearin respectively. Currently, the technique has lost its interest due to the high costs and contamination of the final products with the detergent (M. Kellens et al., 2007).

In solvent fractionation, the crystallization process is performed in a dilute solution with acetone and hexane as a primary solvent to reduce viscosity. In this process, the oil undergoes a short crystallization period and is easy to filter. According to K.K. Rajah, 1996, fractional crystallization from dilute solutions is more efficient with respect to separations than when no solvents are used. Although these benefits are significant, solvent fractionation becomes less interesting due to the high cost of production and initial capital investment (M. Kellens et al., 2007).

In dry fractionation, the molten oil is cooled in a controlled way to crystallize it through a batch crystallization process. The liquid fraction is then physically separated from the solid fraction by means of a vacuum filter or a membrane filter press (M. Kellens, 1994). In this process, no additives are used in the crystallization process and no supplemental post-treatment of the finished products is required. Dry fractionation is therefore a purely natural and physical oil modification process that does not create undesirable by-products. It is the simplest, most environmentally friendly and cheapest fractionation process, which can satisfy today's growing environmental and health concerns by totally or partially replacing chemical modification processes (RE Timms, 2005).

With dry fractionation, it is possible to treat fats that contain a large proportion of higher melting point triacylglycerols, eg milk fat, palm oil and tallow, for total fractionation and to recover both stearin and Olein in large amounts, i.e. typically 20-30% stearin and 70-80% olein. (K.K. Rajah, 1996).

The controlled crystallization of the melt is considered as the structure of any dry fractionation process since this determines the degrees of the olein and stearin fractions obtained. Depending on the crystallization conditions (eg, temperature and time), olein and stearin with various degrees of unsaturation, i.e. different iodine (IV) indices, may be obtained.

The production of olein and stearin fractions from glyceride oils such as palm oil by conventional dry fractionation processes is complicated by the fact that the crystallization process is interrupted by the existence of an elevation in the cooling curve. This elevation arises from the fact that oils and fats consist of a mixture of various triglycerides (TAG), diglycerides (DAG) and free fatty acids (FFA), saturated and unsaturated, which all have different melting points. Therefore, after cooling, some TAGs crystallize, while others remain liquid, depending on their specific cooling behavior. The elevation normally appears on the temperature cooling curve in the transition stage between the nucleation to crystal growth phases.

Controlled cooling during dry fractionation is achieved by pre-selecting a cooling mode based on the temperature of the heat exchange fluid, the oil temperature and the temperature difference between them (delta T). Because the heat is released when an elevation occurs, the temperature is affected and the change of the pre-selected cooling mode during the crystallization process is delayed. This causes the crystallization period to be longer than normal, causing the oil slurry to become more viscous or even sometimes to gel. These properties negatively affect filtration performance because the soft stearin cake tends to stick to the membrane plate when the membrane filter press is depressurized.

Accordingly, there is a need for a dry fractionation process with a relatively short crystallization period that provides fatty crystals that form rapidly and are easily separable, so that high-quantity oily fractions are obtained in high yield.

US 2013/0123524 describes a continuous process for the dry fractionation of edible oils and fats using one or more crystallizers in series, said process comprising the steps of:

a) provide a molten grease,

b) continuously feeding said melted oil or fat to the first of said one or more serial crystallizers in which the fat is gradually cooled using heat exchangers containing a cooling medium such that a glass slurry is formed, showing each one of said one or more crystallizers is a temperature gradient, the temperature being at the point where the melted or partially crystallized fat enters one of the crystallizers greater than the point where the slurry leaves that crystallizer;

c) continuously removing said slurry from the last of said one or more crystallizers,

d) separating said glass slurry by filtration into a filter cake and a filtrate, wherein said process further comprises the step of at least partially melting fat deposits deposited in said heat exchangers.

Document IN 2028 / DEL / 2011 describes a continuous flow method of crystallization of saturated fat from oil, which first comprises subjecting the oil to rapid cooling followed by slow cooling of the oil. After slow cooling, the oil undergoes rapid cooling again. Rapid cooling of the oil is performed at a temperature above the melting point of the oil at which nucleation of the saturated fat begins. This is followed by slow cooling of the oil to a temperature below the oil's melting point to facilitate crystal formation and natural crystal hardening. The method involves further rapid cooling of the oil to a temperature that facilitates maturation of the crystal of the saturated fat.

WO 98/51753 describes a method of fractionating a triglyceride mass, said method comprising the steps of: (a) heating the mixed triglyceride mass to form a melt; (b) cooling the melt to a temperature below the temperature sufficient for crystal growth and above the temperature criticism of the melt to form a super-cooled solution; (c) introducing energy into said supercooled solution sufficient to form crystal nuclei; and (d) growing said crystal nuclei into crystals in a static solution.

Summary of the invention

The inventors have developed an improved process for the continuous fractionation of glyceride oils comprising at least 80% by weight of palm oil which enables the manufacture of a high quality olein fraction in high performance and in a relatively long period of time. short.

The continuous dry fractionation process of the present invention comprises the following successive steps:

(a) providing a liquid glyceride oil that has a temperature that is at least 5 ° C greater than the solidification start point (SOP) of the glyceride oil, the SOP of the glyceride oil being the minimum temperature at which glyceride oil has an N value of 0%;

(b) pre-cool the liquid glyceride oil at a cooling rate of at least 1 ° C / min by passing the glyceride oil through a heat exchanger to reduce the temperature of the liquid glyceride oil to at least 5 ° C at a temperature not less than 10 ° C below the SOP and not more than 5 ° C above the SOP;

(c) homogenizing the pre-cooled glyceride oil to produce a pre-nucleated glyceride oil by passing the pre-cooled glyceride oil through a homogenizer in which the temperature of the glyceride oil is maintained at a temperature within 1 ° C of the pre-nucleation temperature Tp for at least 0.5 hours, said Tp being 0.5-10 ° C below the SOP;

(d) crystallize the pre-nucleated glyceride oil to produce a crystallized glyceride oil containing separable fat crystals by passing the pre-nucleated glyceride oil through one or more crystallizers to reduce the temperature of the pre-nucleated glyceride oil with at least 10 ° C at a crystallization temperature of Tc and maintaining the glyceride oil at a temperature within 1 ° C of Tc for at least 1 hour; and

(e) removing separable fat crystals from the crystallized glyceride oil and recovering an olein fraction from the glyceride oil.

Although the inventors do not wish to be bound by theory, it is believed that the initial stages of the current process, i.e. rapid cooling of the liquid glyceride oil followed by homogenization, induce the formation of small uniform nuclei of trisaturated triglycerides in the oil of glyceride. These nuclei facilitate the accelerated formation of easily separable fat crystals during the subsequent passage of the glyceride oil through one or more crystallizers. The removal of these fat crystals from the glyceride oil produces a high-quality olein fraction (eg, relatively low cloud point) in high yield.

The current process is particularly suited for the dry fractionation of palm oil. The process can be suitably used to produce palm oleins that have an iodine (IV) number in the range of 56 to 64.

In the current process, the liquid glyceride oil is maintained at a temperature within 1 ° C of the pre-nucleation temperature Tp for at least 0.5 hours, said Tp being 0.5-10 ° C below the point of solidification start (SOP) of the glyceride oil, the SOP of the glyceride oil being the minimum temperature at which the glyceride oil has an N value of 0%. For naturally occurring glyceride oils the SOP is significantly higher than the slip melting point of the glyceride oil itself. This is because at the slip melting point these glyceride oils contain some crystalline fat. For example, palm oil typically has a slip melting point of 37 ° C. At the same time, as is evident from the following table, palm oil has a solid fat content at its slip melting point of around 5%.

Determined by pulsed NMR

The present disclosure also provides a system for continuous dry fractionation of glyceride oils, which is useful for understanding the invention without being part of it, comprising:

• A feeding container comprising an outlet;

• A plate heat exchanger comprising an outlet and an inlet that is connected to the outlet of the feed container;

• A homogenizer comprising an outlet and an inlet that is connected to the outlet of the plate heat exchanger;

• A sequence of at least 2 crystallizers that includes a first crystallizer and a last crystallizer, the input of the first crystallizer being connected to the output of the homogenizer; and

• A solid-liquid separator that has an input that is connected to the output of the last crystallizer.

Brief description of the figures

Fig. 1 is a block flow diagram of a continuous process for the dry fractionation of glyceride oils according to the present invention.

Fig. 2 is a process flow diagram showing the process units for pre-cooling, homogenization, and continuous crystallization of glyceride oil in a continuous dry fractionation process according to the present invention.

Detailed description of the invention

Accordingly, one aspect of the invention relates to a continuous dry fractionation process of a glyceride oil comprising at least 80% by weight of palm oil, said process comprising:

(a) Provide a liquid glyceride oil that has a temperature that is at least 5 ° C greater than the solidification starting point (SOP) of the glyceride oil, with the SOP of the glyceride oil being the minimum temperature at which the glyceride oil has an N value of 0%;

(b) Pre-cool the liquid glyceride oil at a cooling rate of at least 1 ° C / min by passing the glyceride oil through a heat exchanger to reduce the temperature of the liquid glyceride oil by at least 5 ° at a temperature that is not less than 10 ° C below the SOP and not more than 5 ° C above the SOP;

(c) Homogenize the pre-cooled glyceride oil to produce a pre-nucleated glyceride oil by passing the pre-cooled glyceride oil through a homogenizer in which the temperature of the glyceride oil is maintained at a temperature within 1 ° C of the pre-nucleation temperature Tp for at least 0.5 hours, said Tp being 0.5-10 ° C below the SOP;

(d) Crystallize the pre-nucleated glyceride oil to produce a crystallized glyceride oil containing separable fat crystals by passing the pre-nucleated glyceride oil through one or more crystallizers to reduce the temperature of the pre-nucleated glyceride oil with at least 10 ° C at a crystallization temperature of Tc and maintaining the glyceride oil at a temperature within 1 ° C of Tc for at least 1 hour; and

(e) Remove separable fat crystals from the crystallized glyceride oil and recover an olein fraction from the glyceride oil.

The term "glyceride" as used herein refers to glycerol esters, one or more fatty acids and optionally another acid, eg, phosphoric acid.

The term "oil" as used herein refers to a lipid material that can be liquid or solid at room temperature (20 ° C).

The term "fat" as used herein, unless otherwise indicated, refers to an oil that is solid or semi-solid at 20 ° C.

The term "solidification start point" or "SOP" is the minimum temperature at which glyceride oil has an N value of 0%. For palm oil the SOP is typically around 45 ° C.

The N value at a temperature of t ° C (Nt) refers to the solid fat content of the oil at a temperature of t ° C as measured by ISO 8292 - Animal and vegetable fats and oils - Determination of content solid fat - pulsed nuclear magnetic resonance method.

It is known in the art that molten oil may have "crystalline memory" so that it appears to recall its previous crystalline history and is influenced toward that conformation during subsequent crystallization. The remnants of the crystalline state after a fat is melted are undesirable in the process of the present invention because this can adversely affect the crystallization process, especially at higher cooling rates. Therefore, in a preferred embodiment, the liquid glyceride oil used in the process according to the present invention has no crystalline memory.

It is possible to destroy all the crystalline memory of a fat or oil by heating it sufficiently. Accordingly, in one embodiment of the current process the used glyceride oil is first heated until all of its crystalline memory is destroyed to provide the liquid glyceride oil. Preferably, the glyceride oil is first heated to a temperature above SOP, more preferably to a temperature that is at least 5 ° C higher than SOP, even more preferably to a temperature that is at least 10 ° C higher than SOP. Typically, the glyceride oil is heated to a temperature of at least 60 ° C, more preferably at least 65 ° C.

The process according to the present invention is preferably used to fractionate a glyceride oil with an SOP of at least 25 ° C. More preferably, the glyceride oil has an SOP in the range of 30-55 ° C.

The glyceride oil comprises at least 80% by weight, more preferably at least 90% by weight and most preferably at least 95% by weight of palm oil. Said palm oil is preferably a deodorized bleached refined palm oil (RBDPO). However, one skilled in the art will recognize that other palm oil products can be used without departing from this invention.

In the current process, the liquid glyceride oil is pre-cooled to shorten the cooling time required in additional process steps. Typically, a heat exchanger is used to pre-cool the liquid glyceride oil. It is preferred that this heat exchanger be a plate heat exchanger. Accordingly, the pre-cooling of the liquid glyceride oil in the current process comprises passing the liquid glyceride oil through a plate heat exchanger unit. Rapid cooling is achieved by improving an effective and efficient heat transfer coefficient between the liquid glyceride oil and the cooling medium (eg chilled water) supplied to the heat exchanger unit.

Preferably, the temperature of the liquid glyceride oil is reduced in the heat exchanger by at least 8 ° C, more preferably by at least 10 ° C, and most preferably by 12-30 ° C. In the heat exchanger the temperature of the glyceride oil is typically reduced to a temperature not less than 8 ° C below the SOP, more preferably to a temperature not less than 5 ° C below the SOP and the most preferably at a temperature that is not less than 2 ° C below the SOP and not more than 3 ° C above the SOP. According to a preferred embodiment, the temperature of the pre-cooled glyceride oil is 40-55 ° C, more preferably 42-52 ° C, and most preferably 45-50 ° C.

The cooling rate used to pre-cool the liquid glyceride oil is preferably at least 2 ° C / min, more preferably 3-10 ° C / min.

To realize the full benefits of the present invention, it is important that the fat crystal precursors, eg small uniform nuclei of trisaturated triglycerides, are formed in the glyceride oil before the crystallization step is brought finished. These precursors begin to form at the prep nucleation temperature Tp, which typically exceeds the slip melting point (SMP) of the glyceride oil. The SMP is the temperature at which a column of solid fat begins to rise in a tube due to buoyancy and because the outer surface of the solid fat is molten. SMP can be measured using ISO 6321: 2002 - Animal and vegetable fats and oils - Determination of the melting point in open capillary tubes (slip point).

According to a preferred embodiment of the current process, Tp is 0.7-8 ° C below SOP, more preferably at least 0.8-7 ° C below SOP and most preferably 1-5 ° C below SOP . Typically, Tp falls in the range of 38 ° C to 48 ° C, more preferably in the range of 39 ° C to 45 ° C, and most preferably in the range of 40 ° C to 43 ° C.

In the process according to the present invention, the pre-nucleation of the pre-cooled glyceride oil takes place during the homogenization step. The homogenization step comprises passing the pre-cooled glyceride oil through a homogenizer. The temperature of the pre-cooled glyceride oil can be further reduced appropriately in the homogenizer, especially if the pre-cooled glyceride oil has a temperature that exceeds the SOP. According to a particularly preferred embodiment, the temperature of the cooled glyceride oil is reduced with 0.5-10 ° C, more preferably with 1-8 ° C and most preferably with 2-6 ° C.

Preferably the homogenization step is performed using a homogenizer comprising a multi-pass blade impeller. Typically, this multi-pass blade impeller is mounted on a vertical axis to provide better agitation during the homogenization process. In the homogenizer, the temperature of the glyceride oil is controlled and maintained within 1 ° C, preferably within 0.5 ° C of Tp for at least 0.5 hours, preferably for at least 1 hour.

To form the separable fat crystals in the pre-nucleated glyceride oil, said oil is passed through one or more crystallizers in the crystallization step (d). In a preferred embodiment, the glyceride oil passes upward through one or more crystallizers.

To promote crystal growth, agitation is preferably used during the crystallization process. Typically, the stirring speed is low enough to minimize secondary nucleation and crystal damage, still enough to promote heat transfer. Accordingly, in a preferred embodiment, the one or more crystallizers used in the current process comprise a mixer or stirrer with or without a surface scraper. More preferably, the one or more crystallizers used in the current process comprise a multiple flat blade impeller. Typically, said multiple flat blade impeller is mounted on a vertical axis.

It is preferred that the one or more crystallizers used in the current process are tubular crystallizers that are cooled by a cooling medium that moves through the crystallizer in countercurrent with the stream of glyceride oil. Preferably the cooling medium is applied both externally and internally to the one or more crystallizers.

In the crystallization step of the current process, crystallization is induced in a controlled manner comprising lowering the temperature of the pre-nucleated glyceride oil to a crystallization temperature Tc at which the fat crystals form. Preferably the temperature of the pre-nucleated glyceride oil is reduced by at least 10 ° C, more preferably by at least 15 ° C, and most preferably by at least 20 ° C. Typically, Tc is in the range of 12-30 ° C, more preferably in the range of 15-28 ° C.

In the current process, the temperature of the glyceride oil in the crystallizers is controlled and maintained at a temperature within 1 ° C of Tc, preferably within 0.5 ° C of Tc for at least 0.5 hours, more preferably of at least 0.8 hours, and most preferably for at least 1 hour.

Crystallization is a highly delicate process. The quality and performance of the crystals produced is very sensitive to the applied temperature gradient, the temperature used and the length of the period of time to which that temperature is applied. It was found that the benefits of the invention are particularly achieved when separable fat crystals form in the pre-nucleated glyceride oil in at least two different temperature and time controlled stages: first nucleating more of the small uniform fat nuclei to facilitate crystal formation and subsequently using the fat crystal nuclei thus produced to crystallize into separable fat crystals. Typically, the first nucleation stage involves faster cooling of the oil than the second crystallization stage.

Accordingly, in a preferred embodiment of the current process, the crystallization of the pre-nucleated glyceride oil comprises:

(d1) passing the pre-nucleated glyceride oil through one or more primary crystallizers to produce a nucleated glyceride oil containing fat crystal nuclei by reducing the temperature of the pre-nucleated glyceride oil with at least ATi ° C to a nucleation temperature Tn that is 8-20 ° C below the SOP of the glyceride oil, said temperature reduction being achieved in a period of ti of 0.5-3 hours; and (d2) passing the nucleated glyceride oil through one or more secondary crystallizers to produce the crystallized glyceride oil by reducing the temperature of the nucleated glyceride oil by at least AT ² ° C and maintaining the glyceride oil at a temperature within 1 ° C Tc over a t ² period of 1-20 hours;

Wherein the cooling steps (di) and (d2) are carried out under mild stirring conditions; and where ATi and AT ² meet the following requirements:

8 <ATi <20;

3 <AT ² <25;

AT2 / t2 <0.7 ATi / ti.

Continuous crystallization of glyceride oil using a series of crystallizing units to achieve a particular cooling profile as described below was found to provide better yields and to reduce the total crystallization period without compromising the quality of the obtained fractions.

The process of the present invention offers the advantage that it employs relatively short crystallization times. Typically, the total residence time of the glyceride oil in the one or more primary crystallizers is in the range of 0.5-2.5 hours, most preferably in the range of 0.8-2 hours.

In a preferred embodiment, ATi is in the range of 9 -8 ° C, more preferably in the range of 10 -5 ° C.

The nucleation temperature Tn is preferably in the range of 27-38 ° C, more preferably in the range of 28-36 ° C, and most preferably in the range of 29-35 ° C.

The temperature reduction ATi is typically achieved in a period ti of 0.7-2.5 hours, most preferably 1-2 hours.

Typically gentle agitation is applied to the one or more primary crystallizers to enhance crystal formation. Preferably gentle stirring is carried out at a speed of less than 25 rpm, more preferably less than 20 rpm.

According to a preferred embodiment of the current process, nucleated glyceride oil from one or more primary crystallizers is transferred to the one or more secondary crystallizers under a gravity flow condition.

Typically, the total residence time of the glyceride oil in the one or more secondary crystallizers is at least 0.5 hours, more preferably at least 1 hour. The residence time in the one or more secondary crystallizers depends on the level of unsaturation of the olein fraction that is produced by the process. The higher the level of unsaturation, the longer the total residence time is needed to produce the olein.

The current process can be used, for example, to produce a highly unsaturated palm olein with an iodine number of 60 or more. To achieve this it is preferred to employ two or more secondary crystallizers to gradually lower the temperature of the glyceride oil to eg less than 20 ° C before removing the fat crystals (stearin) and recovering the olein fraction.

In a preferred embodiment, AT ² is in the range of 4-22 ° C, more preferably in the range of 4.5-20 ° C, and most preferably 5-18 ° C.

In one embodiment of the present invention the glyceride oil is palm oil having an iodine number of 50-55, a SMP of 33-39 ° C and an SOP of 42-52 ° C, Tc is in the range of 18-26 ° C and the palm olein obtained has an iodine number of 56-58.

In another embodiment, the glyceride oil is palm oil having an iodine number of 50-55, a SMP of 33-39 ° C, and an SOP of 42-52 ° C, Tc is in the range of 18-22 ° C and the palm olein obtained has an iodine number of 58-60.

In a further embodiment, the glyceride oil is palm oil having an iodine number of 50-55, a SMP of 33-39 ° C, and an SOP of 42-52 ° C, Tc is in the range of 15- 21 ° C and the palm olein obtained has an iodine number of 60-62.

In yet another embodiment, the glyceride oil is palm oil having an iodine number of 50-55, a SMP of 33-39 ° C, and an SOP of 42-52 ° C, Tc is in the range of 10- 18 ° C and the palm olein obtained has an iodine number of at least 62.

In another embodiment of the process according to the invention, the glyceride oil is a palm oil having an iodine number of 50-55, a SMP of 33-39 ° C and an SOP of 42-52 ° C, and in said Process Fat crystals that are removed from glyceride oil represent 10-20% by weight of that glyceride oil, and these fat crystals have an iodine number of 25-40 and an SMP of 45-56 ° C.

Typically, gentle agitation is applied to the one or more secondary crystallizers to maintain crystal formation and provide sufficient heat transfer during the crystallization process. Preferably, gentle agitation is carried out at a speed of less than 15 rpm.

The glyceride oil crystallized from the one or more secondary crystallizers is subjected to a separation technique to remove separable fat crystals (stearin) from the crystallized glyceride oil and to recover an olein fraction from the glyceride oil. Preferably, in the current process, the separable fat crystals are removed from the crystallized glyceride oil by means of centrifugation and / or filtration. Centrifugation can refer to, for example, a nozzle centrifuge, centrifugal filter, or centrifugal decanter.

More preferably, the separable fat crystals are removed from the crystallized glyceride oil by means of filtration, even more preferably by membrane filtration or hydraulic filtration, and most preferably by membrane filtration.

In a preferred embodiment, step d2 of the current process comprises passing the nucleated glyceride oil through a sequence of at least two secondary crystallizers, including a first secondary crystallizer and a second secondary crystallizer, wherein the temperature of the glyceride oil nucleate is reduced with 4-8 ° C in the first secondary crystallizer and the residence time in the first crystallizer is at least 0.5 hours, and where the temperature of the glyceride oil is reduced with 3-6 ° C in the second secondary crystallizer and the residence time in the second crystallizer is at least 0.5 hours.

Preferably, the temperature of the nucleated glyceride oil is reduced by 4-8 ° C, more preferably by 3-6 ° C in the first secondary crystallizer. Typically, the temperature of the nucleated glyceride oil is lowered in the first secondary crystallizer at 28 ° C or below and more preferably at 27 ° C or below. Typically the residence time in the first secondary crystallizer is at least 0.5 hours, more typically at least 1 hour.

Advantageously, the temperature of the glyceride oil is reduced by 3-6 ° C, more preferably by 3-4 ° C in the second secondary crystallizer, even more preferably at or below 24 ° C and most preferably at 22 ° C or under. Typically the residence time in the second secondary crystallizer is at least 0.5 hours, more typically at least 1 hour.

Preferably, the temperature of the glyceride oil is reduced by 0.5-2 ° C, more preferably by 0.5-1 ° C in each of the additional secondary crystallizers. Typically the residence time in each of the additional secondary crystallizers is at least 0.5 hour, more typically at least 1 hour.

As explained above, pre-nucleation in the homogenization step and crystallization in the crystallization step are suitably performed under stirring. Typically the stirring level employed in the crystallization step is substantially less than in the homogenization step. This is because glyceride oil typically contains larger crystals in the crystallization stage that should not be damaged. Accordingly, in the current process, the homogenization of the pre-cooled glyceride oil comprises passing the pre-cooled glyceride oil through a homogenizer comprising one or more rotary blades and the amount of mechanical power applied to the glyceride oil in the homogenizer exceeds 1x10'3 W / kg, while the crystallization of the pre-nucleated glyceride oil comprises passing the pre-nucleated glyceride oil through one or more tubular crystallizers comprising one or more rotary blades, where the amount of mechanical power applied to glyceride oil in the crystallizer does not exceed 0.1 W / kg, and where the amount of mechanical power applied to the homogenizer is at least 2 times as high, more preferably at least 3 times as high and most preferably at least 4 times as high as the amount of mechanical power applied during cooling of the pre-nuc glyceride oil read on each of the one or more tubular crystallizers.

The present description also relates to a system for the continuous dry fractionation of glyceride oils, which is useful for understanding the invention without being part of it, comprising:

• A feeding container comprising an outlet;

• A plate heat exchanger comprising an outlet and an inlet that connects to the outlet of the feeding container;

• A homogenizer comprising an outlet and an inlet that is connected to the outlet of the plate heat exchanger;

• A sequence of at least 2 crystallizers including a first crystallizer and a last crystallizer, the input of the first crystallizer connecting to the output of the homogenizer; and

• A solid-liquid separator that has an input that is connected to the output of the last crystallizer.

To carry out stirring in the homogenization step as described above, preferably, in the system useful for understanding the present invention, the homogenizer comprises a multi-pass blade impeller.

To perform stirring in the crystallization step as described above, preferably, in the system useful for understanding the present invention, the at least two crystallizers comprise a multiple flat blade impeller.

Fig. 1 is a block flow diagram of a continuous process for the dry fractionation of glyceride oils according to the present invention. The diagram comprises 6 sections:

(A) an oil feed section,

(B) a pre-cooling section

(C) a homogenization section,

(D) a crystallization section,

(E) a filtration section, and

(F) a cooling and freezing section to provide the heat exchange fluid to section B and section D.

Fig. 2 is a process flow diagram showing the process units for the pre-cooling, homogenization and continuous crystallization of glyceride oil in the continuous dry fractionation process according to the present invention.

The oil feed section comprises a feed tank (A ') containing a recycle line to provide continuous agitation during the heating process and for better heat transfer circulation.

The pre-cooling section comprises a plate heat exchanger unit (B ') with chilled water that serves as a rapid cooling means for absorbing heat from the hot feed oil line. Tracing of the steam line is also included in the event of oil fouling in the oil line. Preferably, the supplied chilled water is controlled at a temperature of at least 15 ° C or less to efficiently cool the hot feed oil before it is transferred into the homogenizer unit.

The homogenization section comprises a homogenizer unit (C ') that is equipped with a multi-pitch blade impeller mounted on a vertical axis. This stirrer serves to continuously stir the feed oil during the homogenization process as well as to maintain the desired oil temperature before subjecting said oil to the crystallization process.

The crystallization section comprises six crystallization units indicated as D'1, D'2, D'3, D'4, D'5 and D'6. It is known in the art that the crystallizing units are basically equipped with internal cooling coils and / or cooling fins and / or an external jacket depending on the production scale or size of crystallizer used. In preferred embodiments of the present invention, all crystallizer units are equipped with a vertical flat-blade multiple-shaft impeller such as a stirrer, an internal cooling coil, and an external cooling jacket to provide sufficient heat transfer coefficient during the crystallization process. The internal cooling fins can be used to provide better heat transfer and cooling effect within the crystallizer without separating from the present embodiment.

The filter section may comprise a hydraulic filter press or a membrane filter press (F ') to separate high melting point triglycerides (stearin fraction) from low melting point triglycerides (olein fraction).

In a particular embodiment, the bottom line of the crystallizing unit D'n can become an inlet pipe to receive the glyceride oil from the crystallizing unit D '(n-1) or an outlet pipe to transfer the crystallized glyceride oil to the filter section F ', where n is 3 or greater.

The present invention is further illustrated by the following non-limiting examples.

Examples

The following examples are provided to further illustrate and describe particular embodiments of the present invention, and are in no way intended to limit the invention to the specific procedures, conditions, or compositions described therein.

Physicochemical characterizations of the liquid fraction (olein) and solid fraction (stearin)

After the crystallization process, the glass slurry was subjected to press filtration for the separation process. The weight of the liquid fraction and the solid fraction were measured to determine the percentage of yields obtained. The physicochemical characteristics of both fractions were analyzed for the iodine index (IV), cloud point (Cp) and slip melting point (SMP). The iodine number (IV) indicates the degree of unsaturation of the oil. It is measured according to the MPOB test method p.3.2: 2004, a method described in Ainie et al., “Determination of lodine Value (WJIS) for Palm Oil and Palm Oil Products”, p3.2: 2004. This method is technically equivalent to an industrial method described in ISO3961: 1996; "Animal and Vegetable Fat and Oils".

The cloud point (Cp) is the temperature at which the oil begins to cloud, after crystallization under controlled cooling conditions. It is related to the unsaturation of the oil, and decreases as the unsaturation of the oil increases. The standard cloud point for IV56 palm olein is 10 ° C (max), for IV58 palm olein it is 8 ° C (max), for IV60 palm olein it is 6 ° C (max), and for palm olein IV62 to IV64 it is 3 ° C to 4 ° C (max.).

The slip melting point (SMP) is a temperature at which a fat column of specified length begins to rise in an open capillary tube. It is determined according to the MPOB 25 p4.2: 2004 test method, a method described in Ainie et al., “Method of Test for Palm Oil and Palm Oil Products: Determination of Slip Melting Point”, p.4.2: 2004. The standard slip melting point for refined palm oil is 33 ° C to 39 ° C, for palm stearin RBD is 47 ° C at 54 ° C and for palm olein RBD is 19 ° C at 24 ° C.

Example 1

RBD palm oil with an iodine number (hereinafter referred to as IV) of 52 was heated to a temperature of 60 ° C to 70 ° C in a 70 kg feed tank to destroy the memory of the crystals. The melt was then pre-cooled to a temperature of 45-50 ° C in a continuous mode by passing it through a plate heat exchanger (cooler) in a 50L homogenizing unit where it was kept stirred and kept at room temperature. 40 ° C to 43 ° C.

The homogenized pre-chilled oil was continuously transferred from the homogenizer to the bottom of a jacketed and filled crystallizer 1 until it overflowed into the next crystallizer unit. Crystallizer 1 was supplied with chilled water within the chiller coil and external jacket as a cooling medium. It was continuously stirred at 14 rpm to provide a sufficient heat transfer coefficient to the crystallizer wall and kept the slurry moving. The oil inside crystallizer 1 was cooled to a final oil temperature between 30 ° C to 34 ° C when it was about to overflow and transferred to the bottom of crystallizer 2.

The stirrer speed in crystallizer 2 was adjusted slower than crystallizer 1 by approximately 12 rpm to avoid crystal damage. The oil temperature in crystallizer 2 was further reduced to maintain crystal growth until an oil temperature of approximately 25 ° C to 27 ° C was reached before overflowing and transferring to the next crystallizer unit (crystallizer 3).

The conditions in crystallizer 3 were similarly adapted to achieve a final oil cooling temperature of approximately 24 ° C to 25 ° C. The glyceride oil leaving the crystallizer 3 was subjected to a filtration process. The slurry was removed from the bottom of crystallizer 3 and pumped into a membrane filter press to obtain the olein and stearin fractions.

The three crystallizing units had a similar volume capacity of 25 L each. The oil flow from the homogenizing unit to the series of crystallizing units was maintained throughout the continuous crystallization process.

Three experiments were performed using a slightly different processing condition in crystallizers 1 to 3. The processing conditions employed in the crystallizers are shown in Table 1:

Table 1

Operation condition: Condition 1 Condition 2 Condition 3

TC1 (oil) 30 ° C 32 ° C 34 ° C

Residence time 90 min 90 min 90 min

Shaker speed 14 rpm 14 rpm 14 rpm

TC2 (oil) 26 ° C 27 ° C 26 ° C

Residence time 90 min 90 min 90 min

Stirrer speed 12 rpm 12 rpm 12 rpm

TC3 (oil) 25 ° C 25 ° C 25 ° C

Residence time 90 min 90 min 90 min

Stirrer speed 12 rpm 12 rpm 12 rpm

Total crystallization period 4.5 hours 4.5 hours 4.5 hours

* TC = crystallizer temperature

The properties of the olein and stearin fractions thus obtained were analyzed. The results of the analyzes are shown in Table 2 below. Analytical data is compared with that of palm olein and palm stearin obtained by a conventional batch process.

Table 2

Continuous process

Batch process parameter

Condition 1 Condition 2 Condition 3

Yield (%): olein 80 84.5 82.78 83

Stearin 20 15.5 17.22 17

IV: olein 56.0 56.5 56.55 56.65

Stearin 33.0 29.79 30.44 31.47

SMP (° C): olein 23.2 21.2 21.3 23.2

Stearin 53.0 53.5 54.0 53.5

CP (° C): olein 9.5 9.5 8.9 9.5

In accordance with the present invention, continuous crystallization of palm oil had produced 2% to 4.5% higher yield than batch process with more than 40% reduction in total crystallization period.

Example 2

To measure the consistency of the dry fractionation of palm oil by a continuous crystallization process, a similar test was performed in Example 1 to perform a 3-fold filtration, continuously. After 4.5 hours of crystallization process (including buffer), the slurry was removed from the bottom of crystallizer 3 (buffer) and pumped to a membrane filter press for the filtration process. Again, once crystallizer 3 was nearly filled with grout, the second filtration was performed followed by the third filtration, repeatedly. It takes approximately 90 minutes of buffer time between the second to third processed filtration. The properties of the olein and stearin fraction under three different processing conditions were analyzed and tabulated in Table 3 below.

Table 3

Continuous process

_Parameter Condition 1 Condition 2 Condition 3

Press Press Press Press Press Press Press Press Press 1 2 3 1 2 3 1 2 3

Yield (%): olein 82.7 82.9 83.7 82.5 84.15 81.67 84.59 84.04 83.48

Stearin 15.51 17.27 16.3 17.5 15.85 18.33 15.41 15.96 16.52

IV: olein 56.50 56.87 56.42 56.78 57.62 57.76 57.08 56.78 56.73

Stearin 33.41 32.96 31.75 33.92 31.45 34.17 32.69 32.25 32.56

SMP (° C): olein 22.0 23.3 23.0 22.3 21.7 21.5 20.5 20.7 20.6

Stearin 53.6 53.6 53.5 53.1 53.5 53.0 53.5 53.3 53.6

CP (° C): olein 9.0 9.5 9.3 9.0 9.0 8.8 8.0 8.0 8.5 8.0

According to the present invention, the consistency of the palm oil dry fractionation product by continuous crystallization of the palm oil was not much different in the same processing condition. The olein produced was varied with an average of IV56.6 (condition 1), IV57.4 (condition 2) and IV56.86 (condition 3), respectively. The highest recorded yield was 84% depending on processing condition 3 at the final cooling oil temperature of 34 ° C (crystallizer 1), followed by 26 ° C (crystallizer 2) and 25 ° C (buffer) before undergoing to the filtration process. Furthermore, it can be seen that the quality of the olein obtained, which varies from IV56.42 to IV57.76, was very promising with a CP of 8 ° C to 9.5 ° C and SMP below 24 ° C (max.).

Claims (11)

1. A continuous dry fractionation process of a glyceride oil comprising at least 80% by weight of palm oil, said process comprising: (a) providing a liquid glyceride oil having a temperature that is at least 5 ° C higher than the solidification start point (SOP) of the glyceride oil, with the SOP of the glyceride oil being the minimum temperature at that glyceride oil has an N value of 0%; (b) pre-cool the liquid glyceride oil at a cooling rate of at least 1 ° C / min by passing the glyceride oil through a heat exchanger to reduce the temperature of the liquid glyceride oil to at least 5 ° C at a temperature that is not less than 10 ° C below the SOP and not more than 5 ° C above the SOP; (c) homogenizing the pre-cooled glyceride oil to produce a pre-nucleated glyceride oil by passing the pre-cooled glyceride oil through a homogenizer in which the temperature of the glyceride oil is maintained at a temperature within 1 ° C of the pre-nucleation temperature Tp for at least 0.5 hours, said Tp being 0.5-10 ° C below the SOP; (d) crystallize the pre-nucleated glyceride oil to produce a crystallized glyceride oil containing separable fat crystals by passing the pre-nucleated glyceride oil through one or more crystallizers to reduce the temperature of the pre-nucleated glyceride oil with at least 10 ° C at a crystallization temperature of Tc and keep the glyceride oil at a temperature within 1 ° C of Tc for at least 1 hour; and (e) removing separable fat crystals from the crystallized glyceride oil and recovering an olein fraction from the glyceride oil. 2. The process according to claim 1, wherein the glyceride oil has an SOP in the range of 30-55 ° C. 3. The process according to any of the preceding claims, wherein the heat exchanger used to pre-cool the liquid glyceride oil is a plate heat exchanger. The process according to any of the preceding claims, wherein the Tp exceeds the slip melting point (SMP) of the glyceride oil. 5. The process according to any of the preceding claims wherein Tp is in the range of 40 ° C to 55 ° C, preferably in the range of 40 ° C to 50 ° C. 6. The process according to any of the preceding claims, wherein the homogenizer comprises a multi-pass blade impeller. 7. The process according to any of the preceding claims wherein Tc is in the range of 12-30 ° C. 8. The process according to any of the preceding claims, wherein the crystallization of the pre-nucleated glyceride oil comprises: (d1) passing the pre-nucleated glyceride oil through one or more primary crystallizers to produce a nucleated glyceride oil containing fat crystal nuclei by reducing the temperature of the pre-nucleated glyceride oil with at least ATi ° C to a nucleation temperature Tn that is 8-20 ° C below the SOP of the glyceride oil, said temperature reduction being achieved in a period ti of 0.5-3 hours; and (d2) passing the nucleated glyceride oil through one or more secondary crystallizers to produce the crystallized glyceride oil by reducing the temperature of the nucleated glyceride oil by at least AT ² ° C and maintaining the glyceride oil at a temperature within 1 ° C of Tc over a t ² period of 1-20 hours; Where the cooling stages (d1) and (d2) are carried out under mild stirring conditions; and where AT ¹ and AT ² meet the following requirements: 8 <AT ¹ <20; 3 <AT ² <25; AT2 / t2 <0.7 AT-i / t-i. 9. The process according to claim 8, wherein the nucleation temperature Tn is in the range of 30 ° C to 36 ° C. 10. The process according to claim 8 or 9, wherein AT ¹ is in the range of 9-15 ° C. 11. The process according to any of the preceding claims, wherein the glyceride oil is a palm oil having an iodine number of 50-55, a SMP of 33-39 ° C and an SOP of 42-52 ° C , and wherein a palm olein is obtained after removal of the fat crystals, said palm olein representing 80-90% by weight of said glyceride oil, which has an iodine number of at least 56.