MXPA97004295A - Fractionation of triglicer oils - Google Patents

Abstract

The present invention relates to a process for separating a solid fatty material from a triglyceride acid, which comprises the steps of: a) heating the oil or a solution of the oil in an inert solvent until no substantial amount of the solid material is present b) add a crystallization modification substance to the oil or the oil substance, c) cool the oil resulting in the crystallization of a solid stearin phase, in addition to a liquid olein phase, and d) recover the stearin phase separating it of the olein phase, characterized in that the crystallization modification substance is a polysaccharide which is an inulin or flein with a molecular weight of 500-3990 Da, preferably 1300-2500 Da, of which at least 50% the hydroxyl groups on the saccharide subunits are connected to unbranched alkyl chains (C8-C24) and the remaining hydroxyl groups, optionally, are connected two with an alkyl chain (C1-C

Description

FRACTIONATION OF TRIGLICERIDO OILS DESCRIPTION OF THE INVENTION The present invention relates to a process for fractionating triglyceride oils. The fractionation (fractional crystallization) of triglyceride oils is described by Gunstone, Harwood and Padley in The Lipid Handbook, 1986 edition, pages 213-215. Generally, triglyceride oils are mixtures of various triglycerides that have different melting points. The triglyceride oils can be modified, for example by separating them by crystallization from a fraction having a different melting point or solubility. A fractionation method is the so-called dry fractionation process, which comprises cooling the oil until a solid phase crystallizes and separates the crystallized phase from the liquid phase. The liquid phase is denoted as the olein fraction, while the solid phase is denoted as the stearin fraction. The separation of the phases is usually done through filtration, optionally applying some type of pressure. The main problem encountered with this phase separation in the dry fractionation process is the inclusion of a batch of liquid olein fraction in the separated stearin fraction. The olein fraction thus enters the inter- and intracrystal spaces of the crystal mass of the stearin fraction. Therefore, the separation of the solid from the liquid fraction is only partial. The solids content of the stearin fraction is denoted as the separation efficiency. For the dry fractionation of palm oil, it rarely exceeds 50% by weight, which is harmful to the quality of stearin as well as to the production of olein, for the solvent-related fractionation process, where fat which is going to be fractionated is crystallized from, for example, a hexane or acetone solution, the separation efficiencies can be up to 95% dry fractionation is a procedure that is cheaper and more environmentally friendly than the solvent fractionation For dry fractionation, an increase in the separation efficiency is therefore much more desirable.It is known to interfere with crystallization by adding a crystallization oil to a substance which will generally be indicated as the substance of modification. The presence of small amounts of such a substance in the cooling oil can accelerate, retard or inhibit crystallization. n. In certain situations the above substances are more precisely indicated as crystal habit modifiers. Known crystal modifiers are, for example, sucrose fatty acid esters, described in US 3,059,010 and glucose fatty acid esters and derivatives, described in US 3,059,011. These crystallization modifiers are effective for accelerating the crystallization rate, but they are not reported to increase the separation efficiency. Still, they do not refer to that effect. Other crystallization modifiers, for example, such as those described in US 3,158,490, when added to cooking oils, have the effect that crystallization of solid fat is avoided or at least delayed. Other types of crystallization modifiers, particularly referred to as crystal habitat modifiers, are widely used as an ingredient for mineral fuel oils where waxes are susceptible to crystallization at low temperatures. US 3,536,461 teaches the addition of a crystal habit modifier to a fuel oil with the effect that the temperature of the dark point (or defrosting point) is reduced sufficiently to prevent precipitation of the crystal. Or, alternatively, the solids are induced to crystallize in a different habitat, so that the crystals when formed, can pass through fuel filters without grouping. Other crystal habitat modifiers, in fact, are capable of changing the habitat of crystallized triglyceride fat crystals, so that after crystallization of the crystals, the stearin phase can be more effectively separated from the phase liquid, the olein phase. The pre-published patent application WO 95/04122 relates to dry fractionation using esterified inulins and fleins as crystal habitat modifiers. The publications describing such habitat modifiers are, for example, GB 1 015 354 or US 2,610,915, wherein said such is achieved through the addition of small amounts of a polymerization product of vinyl alcohol esters or a vinyl alcohol replaced. US 3,059,008 describes the use of dextrin derivatives for the same purpose. However, these crystallization modification substances are still far from the ideal. In the first case after three days of crystallization, an increase in olein yield of 71% was reported to only 82%. Although such an improvement can be seen as absolute, there is a need for more powerful crystallization modification substances, which act faster and in a dry fractionation environment and which still provide improvements in olein yield. The selection of such habitat modifiers is a problem, since it is not possible to predict which substances will successfully meet these requirements. - ESTABLISHMENT OF THE INVENTION It has been found that polysaccharide esters are suitable as crystallization modification substances. In contrast to many prior art modifiers, those of the present greatly increase the separation efficiency. Accordingly, the invention relates to a process that employs such modifiers to separate the solid fatty material from a triglyceride oil, which comprises the steps: A. heating the oil or a solution of the oil in an inert solvent until it is not present any substantial amount of the solid material, B. add a crystallization modification substance to the oil or the oil solution, C. cool the resulting oil in a phase crystallization of solid stearin in addition to a liquid olein phase, and D. recovering the stearin phase by separating it from the olein phase, characterized in that the crystallization modification substance is a polysaccharide which is an inulin or "flein with a molecular weight of 500-3990 Da, preferably 1300-2500 Da, of which at least 50% of the hydroxyl groups on the saccharide subunits are connected to unbranched alkyl chains (C8-C24) and the hydroxyl groups or remaining, optionally are connected with an alkyl chain (C1-C7). In a microscopic inspection, the effect of the presence of such crystallization modification substance is that in the oil crystals and crystal aggregates that are formed, which are notoriously different from the crystals obtained without the crystallization modification substance. These crystals and aggregates can be filtered more effectively, since the stearin fraction retains less of the olein fraction even at a low or moderate filtration pressure. The altered crystallization therefore presents a considerable increase in separation efficiency.

DETAILS OF THE INVENTION The oil to be fractionated is mixed with the crystallization modification substance before initiating the crystallization, preferably before the oil is heated, so that all solid triglyceride fat and preferably also the modifying substance They are liquefied, then the oil is cooled to the chosen crystallization temperature.A suitable crystallization temperature is, for example, palm oil, of 15-35 ° C. By choosing a different temperature, the composition of the phases of olein and stearin can change.Crystallization proceeds at the chosen temperature until a constant solid phase content is reached.Crystallization time varies depending on the desired solid phase content.The usual times are on the scale of 4-16 hours, but sometimes the crystallization fat needs more time to reach equilibrium.During crystallization, the oil can be stirred, for example, with a gate agitator. But static crystallization sometimes gives the best separation efficiency. For separation of the solid phase from the liquid phase, a membrane filter press is generally used, since it allows rather high pressures. The proper pressures are 3-50 bars to be exerted for approximately 20-200 minutes. However, even at low or moderate pressure, the stearin phase obtained according to the present invention is easily separated from the olein phase. As a rule, it takes approximately 30-60 minutes to have both phases properly separated. The solids content of the crystal suspension before separation and the separated stearin phase is measured according to the known pulse NMR method (ref Fette, Seifen, Anstrichmittel 1978, .80, nr.5, pp. 180-186). The alkyl chains characteristic of the crystallization modification substances of the present invention are preferably attached to the base structure of the polysaccharide through an ester bridge., for example, a suitable fatty acid or mixture of fatty acids, optionally in the form of an active derivative, is reacted with the hydroxyl groups of the polysaccharide. A method that is particularly suitable since it can be qualified as food grade, comprises the use of the methyl ester of the fatty acid (s) and the peracetate ester of the polysaccharide. By applying common process conditions, such as an appropriate solvent and the presence of a usual basic substance, the reaction of the reactants supplies the desired polysaccharide esters, which can be recovered from the mixture.

The condition that at least 50% of the hydroxyl groups must be esterified should be understood as the minimum degree of esterification of the total amount of hydroxyl groups and not necessarily of the hydroxyl groups of each individual subunit. The base structure of polysaccharide can be the same or different, The best results have been obtained when the size of the alkyl chains attached to the saccharide subunits coincides with the size of the alkyl fatty acid chains of the desired stearin phase. The coinciding part occurs when a substantial part of the chains has the same or approximately the same number of carbon atoms, substantial in this respect, it has to be understood as valid for 60-100% of the chains. Palm oil is fractionated, the preferred alkyl chains are alkyl (C16) alkyl and (C18) alkylstearyl chains.Inulin is a polyfructose which it comprises a glucose terminal subunit, wherein the subunits are mutually connected via a β-1, 2-glycosidic bond. Flein is a polyfructose comprising a terminal subunit of glucose, wherein the subunits are mutually connected via a β-2, 6-glycosidic bond. The molecular weight of inulin or flein is 500-3990 Da, preferably 1300-2500 Da, which corresponds to a chain length (denoted as GFn) of inulin or flein which is n = 2-23, preferably n = 7-14. At least 50% of the hydroxyl groups have been esterified with a fatty acid containing (C 8 -C 24) alkyl, preferably chosen from the group comprising lauric acid, ironic acid, palmitic acid and stearic acid and the remaining hydroxyl groups , have been esterified with a fatty acid containing alkyl (Cl-C7), preferably acetic acid. The molecular weight of inulin fully esterified with three palmitic acid residues is 5.5 *, the molecular weight of non-esterified inulin. A particularly preferred group of inulin esters has been esterified with at least 50% of a mixture of lauric and palmitic acid in a ratio of 9: 1 to 1: 9. This crystallization modification substance is particularly successful in agitated crystallization. The process of the invention is preferably carried out as a dry fractionation process, although the invention is also useful for fractionation with solvent or fractionation of detergent. The process can be applied in triglyceride oils containing relatively high melting fat such as palm oil, palm kernel oil, shea oil, coconut oil, cottonseed oil, lard oil, oil of hydrogenated rapeseed oil, hydrogenated soybean oil or fractions of these oils or oils obtained from the previous oils to - through interesterification. The process is particularly useful for the fractionation of palm oil. Palm oil can be crude, but a refined quality is generally used. The crystallization modification substance is suitably applied in an amount of 0.005-2% by weight, preferably 0.01-1% by weight on the total amount of the oil. A particular advantage of the crystallization modification esters of the present invention is that they are composed of polysaccharides and fatty acids, both are physiologically acceptable, natural substances, and for which a preparation method is available which can be qualified as of food grade. The invention comprises in particular the use of a crystallization modification substance of triglyceride oil of all inulin and fleine esters as described above.

Example 1 Two samples were prepared, each containing • 1200 g of palm oil (neutralized, bleached, -deodorized). The procedure was carried out as a common dry fractionation process, but to the first sample (A), 1.2 g (0.1% by weight) of a crystallization modification substance was added. To the second sample (B), no crystallization modification substance was added. The crystallization modification substance is an inulipa with an average molecular weight of about 1700 Da. It is fully esterified (DS = 3) with a 1: 2 mixture of lauric acid and palmitic acid. Both samples were heated to 65 ° C until they liquefied completely (no solid fat content) and then cooled in order to crystallize. The crystallization proceeded to static conditions at the chosen temperature of 23 ° C, until a constant solid phase content was reached. The samples were compressed on a membrane filter for half an hour. After filtration, the fractions were weighed. The yield of olein is the weight of the filtrate. The yield of stearin is the weight of the glass mass (cake) that remains in the filter. The yields of the measured fractions of stearin and olein are presented in Table 1.

Table 1 Sample A Sample B 0.1% by weight of no temperature modifying modifier / ° C 23 23 stabilization time / h 188 16 content suspension of 15 12 solid phase /% by weight phase content cake 71 34 solid / % by weight olein yield / 79 57% by weight Before filtration, the two samples contained the same amount of solid fat. The comparison shows that the stearin fraction of the sample (A) containing the crystallization modification substance has retained considerably less olein fraction than the sample (B) without a crystallization modification substance. The separation efficiency showed a relative increase of 110%.

Example 2 Example 1 was repeated while allowing the oil to crystallize under agitated conditions. The results of the fractionation are presented in table 2.

Table 2 Sample A Sample B 0.1% by weight of no temperature modifying modifier / ° C 23 23 stabilization time / h 7 5 content suspension of 16.5 13.7 solid phase /% by weight phase content cake 58 53 solid / % by weight olein yield / 72 65% by weight The separation efficiency showed a relative increase of 10%.

Claims (8)

1. A process for separating a fatty material from a triglyceride acid, which comprises the steps of: a. heating the oil or a solution of the oil in an inert solvent until no substantial amount of the solid material is present, b. add a crystallization modification substance to the oil or the substance of the oil, c. cooling the resulting oil in the crystallization of a solid stearin phase, in addition to a liquid olein phase, and d. recovering the stearin phase separating it from the olein phase, characterized in that the crystallization modification substance is a polysaccharide which is an inulin or flein with a molecular weight of 500-3990 Da, preferably 1300-2500 Da, of which less 50% of the hydroxyl groups on the saccharide subunits are connected to unbranched (C8-C24) alkyl chains and the remaining hydroxyl groups, optionally, are connected with an (C1-C7) alkyl chain.

2. The process according to claim 1, characterized in that the alkyl chains are connected to the polymer chain through an ester bridge.

3. The process according to claim 2 or 3, characterized in that the inulin has been esterified by at least 50% of one or more fatty acids selected from the group consisting of lauric acid, myristic acid, palmitic acid and stearic acid, while the resulting hydroxyl groups are free or have been esterified with acetic acid.

4. The process according to any of claims 1-3, characterized in that the hydroxyl groups of the inulin have been esterified with a mixture of lauric and palmitic acid in a ratio of 9: 1 to 1: 9, while the remaining hydroxyl groups they are free or have been esterified with acetic acid.

5. The process according to any of claims 1-4, characterized in that it is applied as a dry fractionation process.

6. The process according to any of claims 1-5, further characterized in that the triglyceride oil to be fractionated is palm oil, palm kernel oil, shea oil, coconut oil, cottonseed oil, butter oil, hydrogenated rape seed oil, hydrogenated soybean oil or fractions of these oils or oils obtained from previous oils through interesterification.

7. The process according to any of claims 1-6, characterized in that the crystallization modification substance is used in an amount of 0.005-2% by weight, preferably 0.01-1% by weight in the total amount of the oil.

8. The use of an inulin or fleine ester as defined in any of the previous claims as a crystallization modification substance of triglyceride oil.