Process for the production of fats from cruciferae oil

Abstract: High erucic cruciferae oils are interesterified with C₁₆ or higher fatty acids or derivatives thereof. The use of a 1,3-selective lipase leads to the introduction of the fatty acid groups in the 1,3-positions. The liberated erucic acid (derivative) can be hydrogenated; the behenyl acid (or derivative) thus formed can be recirculated to provide at least 50% of the behenyl acid (derivative) needed in the process. The products obtainable by these processes, display good anti-blooming properties.

Description: This invention relates to a novel preparation of triglycerides by rearrangement under the influence of lipase enzymes of cruciferae oils. The rearrangement of fats and oils under the influence, as rearrangement catalyst, of lipase enzymes in a substantially non-aqueous medium has already been disclosed in our British patent specification N° 1577933. Under the influence of the catalyst, the fatty acid residues of the triglycerides, of which glyceride oils and fats are largely composed, may be rearranged selectively or non-selectively according to the characteristics of the catalyst. Different fatty acid residues may be introduced into a particular triglyceride from another triglyceride or from free fatty acid or alkyl ester thereof included in the reaction medium, which is conducted in liquid phase in the presence or absence of added solvent, which should be water-immiscible, although a small amount of water is introduced with the catalyst and may also be present in the reaction medium to maintain the activity of the catalyst. It has already been proposed in EP 233,036 to prepare saturated triglycerides containing C₁₄ and shorter-chain fatty acids by rearrangement with such acids or their alkyl esters of vegetable oils, including rapeseed oil, in the presence of 1,3-selective lipase enzymes as rearrangement catalysts, the oil or the rearranged product being saturated by hydrogenation. An important aspect of the 1,3-selective lipase rearrangement process is the conversion of cheap vegetable oils containing a high proportion of unsaturated fatty acid residues to symmetrical disaturated triglycerides of stearic and palmitic and higher fatty acids, of which cocoa butter and other expensive vegetable butters are largely composed, to provide fats replicating the melting profiles, for which vegetable butters are highly prized, for use in chocolate, confectionery generally and non-food applications in the pharmaceutical industry. The source of feedstock for lipase rearrangement processes imposes some limitations on the characteristics of the rearrangement product where the catalyst is selective in action. Thus, a 1,3-selective lipase provides a rearrangement product in which the fatty acids occupying the 1- and 3-positions of its triglycerides are randomly distributed, leaving the 2-position fatty acids unchanged. Where therefore the feedstock consists of highly unsaturated triglycerides, as, for example, in vegetable oils, which are subjected to 1,3-selective rearrangement to obtain symmetrical disaturated triglycerides, these may contain a higher proportion in the 2-position of polyunsaturated fatty acids containing more than one double bond than are found in the corresponding triglycerides of cocoa butter and similar vegetable butters consisting substantially of 2-oleyl triglycerides. It has, however, been proposed to use as feedstock for 1,3-selective rearrangement processes, vegetable oils, e.g. sunflower and safflower oil from seed varieties yielding high oleate oils and thus containing fewer linoleic and more highly unsaturated fatty acids than appears in more familiar varieties. Moreover, whereas palmitic acid, and particularly stearic acid, may be readily obtained from vegetable oils for use in these lipase processes, longer-chain saturated fatty acids, such as arachidic and behenic acids, are less widely available for the preparation of the corresponding 1,3-disaturated triglycerides. According to EP 276 548 a fatty acid mixture, rich in behenic acid is obtained by hydrogenating high erucic rapeseed oil, hydrolysis of the hardened product and fractionation of the mixture of acids obtained. The product enriched in behenic acid can be converted with a high oleic vegetable oil, such as high oleic sunflower oil. A similar process is disclosed in EP 196 780 for the production of triglycerides rich in behenic acid. EP 245 076 states that for the production of SOS-fats it is advantageous to start from oils high in 2-oleic acid. Nothing is disclosed about the use of high erucic rapeseed oil. In EP 237 307 a chemical interesterification process is disclosed, using Na-methanolate as base. This process, however, will result in a randomized product and not in directed products. According to EP 227 364 a mixture is obtained by blending of high erucic and low erucic rapeseed oil. This mixture is hydrogenated; the hardened mixture is hydrolyzed; the fatty acids obtained are esterified and the ethyl esters are converted enzymically with an oil, high in 2-oleate. Therefore, the above references do not indicate a process, wherein the erucic groups present in the starting oil are applied, as an internal source for the provision of behenic acid that is used for the exchange of the erucic groups by behenic acid groups. We have now found that these limitations may be minimized in an improved process for the rearrangement of triglycerides in a cruciferae oil under the influence, as rearrangement catalyst, of a 1,3-selective lipase enzyme and in the presence of a saturated, free fatty acid or ester thereof, wherein the rearrangement is carried out with a cruciferae oil having a content of erucic acid of at least 20 wt%, wherein the erucic groups are bound predominantly in the 1,3-positions, while the fatty acid or ester derivative thereof has a chain length of at least 16 carbon atoms and is rich in behenic acid after which the erucic acid or its ester derivatived thus formed is hydrogenated catalytically and the behenic acid or derivative thus formed is recirculated to the rearrangement process. Rape, mustard (B. Alba, B. nigra) and crambe (Crambe Abyssinica) seed oils all belong to the cruciferae family; they all contain significant quantities of erucic acid which are predominantly in the 1,3-positions, the 2-position being occupied predominantly by unsaturated fatty acids (oleic, linoleic and linolenic acids) [cf. The Lipid Handbook, F.D. Gunstone, J.L. Harwood, F.B. Padley, 1986 , p. 52]. Although varieties are known that combine a high 1,3-erucic acid content with a C₁₈ polyunsaturated fatty acid content that is less than, and sometimes substantially less than, the oleic acid content, more varieties are known in which the content of polyunsaturated fatty acids in the 2-position is higher than the oleic acid content (e.g. 28% C 18:1 ; 41% C 18:2 and 29% C 18:3 are very common). So, in contrast to high oleate C₁₆/C₁₈ vegetable oils, high oleate rapeseed oils generally contain appreciably more linoleic and linolenic acid in the 2-position, with the result that 1,3-rearranged derivatives contain significantly more 2-linoleoyl and 2-linolenyl triglycerides than are correspondingly produced from the high oleate C₁₆/C₁₈ vegetable oils. An important aspect of the invention is that it benefits from the fact that in high erucic rapeseed oils the erucic acid is enriched at the 1,3-positions, only 3.6% being reported in the 2-position (Brockerhoff 1963). According to a particular feature of the present invention a process is disclosed for the preparation of either mono- or di-behenoyl-2-mono- and poly-unsaturated fatty acid-containing triglycerides comprising selective rearrangement of high erucic cruciferae oil feedstock under the influence, as rearrangement catalyst, of a 1,3-selective lipase enzyme in the presence of behenic acid or a derivative, in particular an alkyl ester thereof, at least part of which is provided by hydrogenating erucic acid or its corresponding alkyl ester separated from the rearrangement product. The reaction products containing behenoyl in the 1- and/or 3-positions and C₁₈ polyunsaturated fatty acid residues in the 2-position display anti-blooming behaviour in chocolate compositions. We prefer, however, to use a feedstock that comprises a high erucic seed oil, containing as few polyunsaturated C₁₈ fatty acid residues as possible. In this way, a rearranged product is obtained in which the 2-position is predominantly occupied by oleic acid residues. Optionally, residual amounts of dibehenyl triglycerides of C₁₈ polyunsaturated fatty acids may be removed from dibehenoyl 2-oleyl triglyceride by a refining process. In this process, the product obtained after interesterification is separated into a triglyceride-containing fraction and a fraction that contains at least the liberated erucic acid or derivatives thereof. This can be achieved by any means disclosed in the art (e.g. GB 1,577,933). In this way, chocolate fat compositions can be obtained that display good anti-blooming properties. These compositions are characterized by the presence of 2-10 wt.%, preferably 5-7 wt.%, of 1,3-dibehenoyl-2-oleyl triglyceride (= BOB); 5-14 wt.%, preferably 7-10 wt.%, of 1,3-dibehenoyl-2-linoleoyl triglyceride (= BLnB) and 2-10 wt.%, preferably 5-7 wt.%, of 1,3-dibehenoyl-2-linolenyl triglyceride (= BLNB). The fraction that contains the erucic acid moieties is catalytically hydrogenated. This can be done by known methods (cf., for example, Freifelder, Practical Catalytic Hydrogenation (Techn. and Applications), 1971 , pp. 132-134). The preferred catalyst is platinum-on-carbon but Raney nickel also leads to good results. In this way more than 50% of the behenic acid needed in the process can be supplied by the starting material (high 1,3-di-erucic rapeseed oil). So the normal procedure consists of enzymatic interesterification using a high erucic rapeseed oil and a behenic acid-containing mixture of fatty acids as reactants. The interesterification is carried out with a 1,3-specific lipase. A solvent, i.e. hexane, is used in order to obtain a liquid. After the interesterification, the diglycerides are removed from the crude reaction products by enzymatic hydrolysis using an enzyme specific for the hydrolysis of diglycerides. The free fatty acids are removed from the reaction product by steam distillation. The fraction containing fatty acids is hydrogenated and the hydrogenated product is recycled. The fraction that contains the triglycerides is wet-fractionated. An olein fraction is separated from a stearin fraction. The olein fraction is recirculated while the stearin fraction is wet-fractionated again. A second stearin fraction consisting mainly of tri-sats is separated from a mid-fraction. The mid-fraction mainly consists of mono- and di-behenoyl triglycerides. This fraction can be used as anti-blooming agent. EXAMPLE 100 g high erucic rapeseed oil (see Table I) was mixed with 100 g of a fatty acid mixture (obtained by hydrolyzing a hardened rapeseed oil). This mixture was dissolved in 5 l hexane. 50 g enzyme (a 1,3-specific lipase, known as SP-392 ex NOVO) on celite as carrier was added to the mixture. Interesterification was performed at 60°C. After 1.5 h reaction time, a mixture was obtained in which the triglyceride showed the composition according to Table II (FAME analysis). High erucic rapeseed 2-Position Fatty acids mixture FAME FAME C 14:0 0.1 - 0.1 C 16:0 4.1 - 4.0 C 16:1 0.3 0.2 0.2 C 18:0 1.1 0.1 46 C 18:1 13.5 28.6 - C 18:2 15 41.2 - C 18:3 10.7 29.2 - C 20:0 9.6 0.53 4.7 C 22:0 0.5 0.1 44 C 22:1 45.1 0.9 - C₂₄ 0.2 - 0.6 Interesterification product FAME 2-position C 14:0 - - C 16:0 2.7 - C 16:1 0.1 0.5 C 18:0 17.2 1.7 C 18:1 9.6 27.2 C 18:2 12.8 39.2 C 18:3 8.7 27.6 C 20:0 5.3 0.9 C 22:0 21.9 1.5 C 22:1 20.3 0.9 C₂₄ 0.7 - The product was subjected to steam distillation. The material containing fatty acids was worked up so as to recover a concentrated mixture of fatty acids. The mixture was hydrogenated, using Pt/C as catalyst. The hydrogenation performance is nearly complete. The hydrogenated acids are recirculated to the interesterification step. The triglyceride fraction is wet-fractionated, using 6 volumes of acetone per weight unit of triglycerides. The mixture was cooled to -5°C. The stearin fraction was separated from an olein fraction containing solvent. After removal of the solvent, the olein was recirculated. The composition of the stearin fraction is mentioned in Table III. Stearin fraction Tri-sats. 7.8 St O St 7.5 St Ln St 10.7 St LN St 7.5 BOB 5.7 ) Total : BLnB 8.1 ) dibehenoyl : BLNB 5.7 ) 19.5% St O B 12.9 ) Total : St Ln B 18.7 ) monobehenoyl : St LN B 13.1 ) 44.7% Others up to 100% St = Stearic Ln = Linoleic LN = Linolenic O = Oleic

Claims: Process for the rearrangement of triglycerides in a cruciferae oil under the influence, as rearrangement catalyst, of a 1,3-selective lipase, in the presence of a saturated fatty acid or ester thereof, wherein the rearrangement is carried out with a cruciferae oil having an erucic acid content of at least 20 wt% wherein the erucic groups are bound predominantly in the 1,3-positions, while the fatty acid or ester derivative thereof has a chain length of at least 16 carbon atoms and is rich in behenic acid, after which the erucic acid or its ester derivative thus formed is hydrogenated catalytically and the behenic acid or derivative thus formed is recirculated to the rearrangement process. Process according to claim 1, wherein the cruciferae oil is a high erucic rapeseed oil. Process according to claim 1, wherein the erucic acid content of the oil is at least 35 wt%. Process according to claim 1, wherein the high erucic rapeseed oil is rich in 2-oleyl groups.

Inventors: PADLEY FREDERICK BOLTON, PADLEY, FREDERICK BOLTON
Applicants: UNILEVER NV, UNILEVER PLC, UNILEVER N.V.
Application year: 1990
Main classification: C11C3
IPC codes: C12P7, A23G1, A23D9, C11C3