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United States Patent (19) 11 Patent Number: 4,585,593 Keulemans et al. (45) Date of Patent: Apr. 29, 1986

54 INTERESTERIFICATION PROCESS AND 4,284,578 8/1981 Lathauwer et al...... 260/410.7 APPARATUS 4,335,156 6/1982 Kogan et al...... 260/410.7 X (75) Inventors: Cornelis N. M. Keulemans, FOREIGN PATENT DOCUMENTS Rozenburg; Gerard Smits, 55-012146 1/1980 Japan. Rotterdam, both of Netherlands 57-047396 3/1982 Japan. 73. Assignee: Lever Brothers Company, New York, 796808 11/1955 United Kingdom . N.Y. 767085 9/1980 U.S.S.R. . (21) Appl. No.: 690,820 OTHER PUBLICATIONS 22 Filed: Jan. 11, 1985 J. Am. Oil Chemists' Soc., 44414A (1967). Journal of the American Oil Chemists Society, 55, 1978 Related U.S. Application Data (796) (Sreenivasan). 63 Continuation of Ser. No. 422,778, Sep. 24, 1982, aban Primary Examiner-Helen M. S. Sneed doned. Attorney, Agent, or Firm-James J. Farrell (30) Foreign Application Priority Data (57) ABSTRACT Oct. 6, 1981 GB) United Kingdom ...... 813013S The process is a continuous process and comprises bringing together streams comprising a triglyceride oil 51 int. Cl." ...... C11C3/02 and a catalyst solution of water, sodium and 52 U.S. Cl...... 260/410.7; 422/224 glycerine respectively, homogenizing the mixture, re 58) Field of Search ...... 260/410.7; 422/224 ducing its water content, and interesterifying. Prefera (56) References Cited bly the homogenization and drying steps take place consecutively and are combined and are performed by U.S. PATENT DOCUMENTS passage through a spray drying nozzle. The efficiency 2,309,949 2/1943 Gooding . 2,474,740 6/1949. Ittner ...... 260/410.7 of the homogenization and drying steps allows the in 2,738,278 3/1956 Holman et al...... 260/410.7 X teresterifying step to take place in about 4 minutes and 3,095,431 6/1963 Giddings et al. . thus permit operation of the process in a continuous ac.

3,170,798 2/1965 Burgers et al...... 260/410.7 X 3,271,434 9/1966 Baenitz ...... 260/410.7 4,263,216 4/1981 Volpenhein ...... 260/410.7 23 Claims, 8 Drawing Figures U.S. Patent Apr. 29, 1986 4,585,593

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NOILV)-23 IS383LN % 4,585,593 1. 2 solution; (ii) homogenising the oil and catalyst solution INTERESTERFICATION PROCESS AND by subjection to energetic shear; (iii) reducing the water APPARATUS content of the homogenised mixture so as to allow the formation of an active catalyst component as herein This is a continuation of Ser. No. 422,778, filed Sept. 5 defined; and (iv) holding the resulting mixture at a tem 24, 1982, now abandoned. perature sufficient to cause interesterification. The present invention relates to a process and an The continuous confluence of two streams followed apparatus for the interesterification of fats and oils and by homogenisation can allow a very fine and rapid to the fats and oils so treated. In the present specifica dispersion of the aqueous catalyst solution to be tion the terms "fats' and "oils' are used interchange 10 achieved in the oil. The size of the aqueous droplets ably. determines the rate of water removal as well as the Molecular rearrangement of triglycerides is a tool surface area between the catalyst and the oil and can well known in the art to adjust the physical characteris thus influence the time necessary to complete the intere tics of a fat or oil. Interesterification of the fatty acid sterification reaction. We have for example found that moieties can for example alter the melting point of a 15 aqueous droplets as small as about 10.5 m can be triglyceride composition without substantially effecting achieved on homogenisation, which on water removal its overall fatty acid composition. give catalyst particles of from about 2 to about 10 um A review article in J.A.O.C.S. 44414A(1967) entitled which bring about at least 90% interesterification "Interesterification Products and Processes' describes a within about 4 minutes. A continuous throughput of variety of process conditions and catalysts capable of 20 triglycerides is thus possible without a long residence bringing about the reaction. It refers for example to time for any part of the process. U.S. Pat. No. 3,170,798 which is an example of a batch Use of an on-line process can moreover allow very process. The oil, which if necessary has been pre-neu short contact times between the initial confluence of the tralised by heating with an aqueous alkaline solution to streams and the subsequent removal of water. Due to reduce its free fatty acid content to not more than 0.1%, 25 the variety of reactions which can occur on admixture is placed in a reaction vessel and the catalyst comprising of the catalyst solution and the oil the prompt removal a mixture of water, an alkali metal hydroxide and glyc of water to a value of less than 0.03 wt %, preferably erine is stirred into the oil. The reaction mixture is less than 0.01 wt % (as measured by the Karl-Fischer heated to a reaction temperature and the reaction is method), can be advantageous in furthering the desired allowed to proceed for between 30 minutes and 1 hour. 30 interesterification reaction. The water is necessarily The process described in U.S. Pat. No. 3,170,798 there present initially to act as a carrier for the alkali metal fore suffers inter alia from a long reaction time required hydroxide and glycerine and to aid their dispersal in the to effect interesterification. The specification moreover oil and is moreover produced by the action of the cata emphasises the need to reduce the free fatty acid con lyst. tent to less than 0.1 wt % in order to effect successful 35 interesterification. Sreenivasan (J.A.O.C.S. 55 (1978) The following are the more important reactions 796) therefore views the batch process as a two stage which are thought to occur following admixture of the reaction involving two distinct heating steps, one at a tWO Streams: low temperature of 60° C. under vacuum to effect neu tralisation, water removal and catalyst dispersion and H2O 1. the second at a higher temperature for interesterifica (a) MOH + glycerine s =&M glycerolate (insoluble in oil) tion. (b) M glycerolate -Gactive catalytic component A continuous process referred to at page 454A in the Rate of reaction (b) is increased in the presence of mono review article in JAOCS 44 comprises that described in and diglycerides. U.S. Pat. No. 2,738,278. The process there described 45 involves the use of an aqueous alkali metal hydroxide as the catalyst. The specification teaches continuously triglyceride introducing a flowing stream of aqueous alkali metal MOH -- monoglyceride saponification eM salt of fatty acids hydroxide into a flowing stream of the ester material diglyceride being subjected to molecular rearrangement. Disper 50 sion of solid hydroxide is said to occur following Rate of reaction is increased in presence of water. "flash' removal of the moisture. Reaction times of 5 minutes or less are claimed in the specification. Such MOH + free fatty acid neutralisation- M salt of fatty acids 3. short reaction times are however only obtained when relatively high catalyst concentrations with respect to 55 Removal of water from the system thus encourages the oil are employed. The process described in U.S. Pat. the equilibrium of reaction 1(a) to shift in the desired No. 2,738,278 therefore suffers from the disadvantage direction towards the M glycerolate and discourages that acceptable rates of reaction for a continuous pro reaction 2. The discouragement of the saponification cess are only achieved at the expense of high oil losses reaction reduces the amount of triglyceride and alkali due to saponification in the presence of excess hydrox metal hydroxide lost. ide. The presence of mono and diglycerides is believed to According to a first aspect of the present invention effect the rate constant of reaction 1 in two ways. there is provided a process for the interesterification of Firstly the mono and diglycerides preferentially un a triglyceride oil employing a catalyst solution compris dergo interesterification compared to triglycerides. ing a mixture of water, an alkali metal hydroxide and 65 During their interaction with the catalytic solution an glycerine, characterised by performing the process as a intermediate is formed, which is believed to be M dia continuous process comprising (i) bringing together cylglycerol, which promotes the interesterification of streams comprising respectively the oil and the catalyst the triglycerides. Secondly mono and diglycerides also 4,585,593 3 4 preferentially saponify compared to triglycerides. The The interesterification temperature is preferably in portion of mono and diglycerides which therefore un the range of from 100' to 160° C., more preferably in the dergoes saponification before the reaction is substan range of from 125 to 150° C. The temperature selected tially halted due to the removal of the water, provides depends on the overall desired reaction rate. The reac soaps which, in addition to the mono and diglycerides tion rate increases with increase in temperature, but is remaining in the reaction mixture, produce an emulsify also dependent on the degree of homogeneity and water ing action with respect to the immiscible phases. The removal achieved in the mixture and on the catalyst more important contribution, particularly that of the composition concentration. An acceptable residence monoglycerides, to enhancing the overall interesterifi time of four minutes for an interesterification reaction cation rate of the triglycerides is however the first 10 was achieved employing a temperature of 135 C. mechanism outlined above. Rapid removal of water Temperatures in the above range are moreover pre from the system to a low level thus favours the enhanc ferred as the same temperature range has been found to ing effect of the mono and diglycerides present. The be suitable for the homogenisation and water removal monoglycerides are preferably present in the oil at an steps. optimum level of about 2 wt % based on the total 15 The catalyst concentration as well as the relative weight of the oil. As partial glycerides are however proportions of each component of the catalyst solution usually present in an oil the most cost effective level can be varied over a relatively wide range. Preferably with regard to the interesterification may be that at for a catalyst comprising /glycerine/- which they occur naturally. water the weight ratios of the three components should Contrary to prior art processes however we have 20 be respectively between 1/2/3 and 1/2/7. A weight found that it need not be necessary to pre-neutralise ratio of 1/2/3 is preferred to minimise the drying step. fatty acids present so as to incur a two step process. If At high interesterification temperatures the sodium neutralisation is necessary, additional alkali metal hy hydroxide:water ratio may be reduced still further to droxide can be incorporated in the catalyst solution. 1:2. Somewhat more glycerine may then however need The soaps then formed in situ in the reaction mixture 25 to be incorporated in the catalyst solution, e.g. to give a have been found to have a beneficial emulsifying effect, NaOH:glycerine ratio of about 1:3. hydroxide, particularly with respect to retaining the aqueous drop or can be em lets containing the alkali metal glycerate and preventing ployed in place of sodium hydroxide. The relative rates the deposition of catalyst particles. We have found for of reaction for the four alkali metal are example that oils containing from about 0.2 to 1.0 wt % 30 LiCNa

The drying pressure determines the rate and the over The results given in Table IV below further illustrate all amount of water removal. Acceptable results were the necessity of homogenising the catalyst solution and only obtained in the present case when the drying pres oil mixture prior to reducing its water content. The sure was not more than 20 mb. Drying pressures greater results are given in terms of droplet size of dispersed than 20 mb (runs 4 and 8) did not lead to interesterifica 30 catalyst solution. The experiments consisted in spraying tion. a soyabean oil with a 0.1 wt % of a 1:2:7 NaOH:- glycerine:H2O catalyst solution through the dryer at EXPERIMENT 2. varying pressure differences across the nozzle and vary Comparative trials were performed employing batch ing drying pressures within the spray-drying tower. As G to determine the effect of homogenising the oil and can be seen from Table IV the mean droplet size is catalyst mixture prior to drying. In one run the static determined by the pressure across the nozzle and hence mixer illustrated in FIG. 2 was included in the apparatus the degree of homogeneity imparted to the mixture. and in a second run the static mixer was omitted. In The mean droplet size is not affected by the pressure in each case the pressure drop over the nozzle was the the spray drying tower, i.e. it is not determined by the same. The total pressure drop, and hence degree of vaporisation of the water. TABLE IV PRESSURE IN PRESSURE FLOWRATE MEAN DROPLET RUN THE DRYER DROP RATE SIZE NO. (mb) (b) (kg/h) (min) 020 0.9 60 8.0 12 30 0.9 60 8.5 13 4. 0.9 60 8.5 14 4. 0.9 60 8.5 5 4 3.8 120 4.2 homogenisation, was consequently much greater in the system including the static mixer. In each case the cata lyst employed was a 1:2:3 solution of NaOH:glycerine:- EXPERMENT 3 water, the interesterification temperature was 125 C., In the following experimental runs the pressure drop the drying pressure was 4 mb and the flow rate was 42 55 across the spray drying nozzle is varied. For each set of kg/hr. conditions there was found to be a minimum pressure The results of the comparative runs are given in which must be exceded before complete randomisation Table III. will occur. If the minimum pressure is not attained, the TABLE III degree of homogeneity is reduced and hence the aque RUN % NaOH HOMO). INT % p 60 ous droplet size is increased and the effectiveness of the NUMBER (ONOIL) GENISER min INTEREST (b) drying step and the amount of contact area between the 9 0.08 yes s7 100 25 catalyst and the oil are decreased. 10 0.10 nO 60 O 0.4 Table V gives the NaOH concentration (on oil), flow *The pressure drop over the homogeniser was about 24.6 b and 0.4b over the rate, pressure drop and time required to achieve com nozzle. 65 plete randomisation for three runs employing batch D at 125 C. interesterification temperature and a drying The results illustrate the necessity of homogenising as pressure of 4 mb using a 1:2:7 NaOH: glycerine:water well as drying the oil and catalyst mixture in order to catalyst solution. 4,585,593 9 10 TABLE V was maintained in the spray drying tower. The tempera RUN 2 NaOH FLOW RATE PRESSURE INT ture of the rection mixture on drying was the same as NUMBER (On Oil) (kg/h) DROP (b) (min) the temperature in the reaction vessel and was 145 C. 6 0.15 60 1 37 TABLE VIII 17 0.14 90 2.3 17 RUN 7% NaOH Ap FLOW RATE tINT 18 0.13 120 4. 13 NUMBER (ONOIL) (b) (kg/h) % INT (min) 28 0.062 2.8 90 >90 3 For each run the water content in the reaction mix 29 0.053 2.8 90 85 6 30 0.065 4. 120 >90 1 ture after drying was less than 0.01 wt %. The time 31 0.055 4. 120 >90 1 required to achieve complete randomisation however 32 0.056 13 200 >90 1 increased with a decrease in the pressure drop. 33 0.048 13 200 >90 Table VI illustrates the need to achieve a minimum pressure drop across the nozzle. The blend used was batch D at an interesterification temperature of 135° C. 15 EXPERIMENT 4 and a drying pressure of 4 mb. The catalyst was a 1:2:3 Experiments were performed on a variety of oil solution of the NaOH:glycerine:water. Run 19 employ blends to establish the minimum amount of NaOH re ing a pressure drop of 1.3b gave no interesterification quired in a 1:2:3 NaOH:glycerine:water solution to after 45 minutes whilst Run 20 employing a pressure bring about complete randomisation. In each case the drop of 4.5b gave complete randomisation after only 9 interesterification temperature was 125 C. The results minutes. are given in Table IX. TABLE VI TABLE IX RUN % NaOH p FLOW RATE INT FLOW MIN NUMBER (ONOIL) (b) (kg/h) (min) % INT RUN RATE % NaOH 19 0.08 1.3 60 45 0 25 NUMBER OL (kg/h) (ON OIL) 20 0.08 4.5 120 9 90 34 Blend I 60 0.05-0.06 35 Batch A 60 0.07-0,08 36 Biend J 120 0.10 Table VII gives the results in terms of interesterifica 37 Batch B 100 0.08 tion times for oils homogenised and dried at various 38 Blend K 100 0.07 pressure drops across hollow cone nozzles of varying 39 Blend L 120 0.10 sizes. In each case the catalyst employed was a 1:2:3 solution of NaOH:glycerine:water, the interesterifica Blend I was a mixture of 60 wt % deodorised and tion temperature was 125 C. and the drying pressure neutralised palm oil and 40 wt % coconut oil. was 4 mb. With the exception of run 25 complete ran Blend J was a mixture of 25 wt.% sunflower oil, 45 wt domisation was achieved within the time stated. After % palm oil hardened to a melting point of 44' C. and 35 45 minutes no interesterification took place in run 25 wt % coconut oil. which employed the widest nozzle at the lowest pres Blend K was a mixture of 40 wt % neutralised and Ste. bleached palm oil and 60 wt % palm kernel oil. TABLE VII FLOW RUN % NaOH Ap RATE INT NUMBER OIL (ONOIL) NOZZLE (b) (kg/hr) (min) 21 Blend H 0.07 1.00mm-30 - 7 86 9.6 22 Blend H 0.07 f 2.4 50 44 23 Blend F 0.07 2.1 mm-90 18 195 5.7 24 BlendF 0.07 f 3.8 110 14 25 Blend F 0.07 y 1.2 60 >45 26 Blend H 0.09 1.5 mm-90' 7.1 58 13 27 Bend H 0.10 2.5 42 65 Blend H was a 95:5 mixture of soyabean oil and soya bean oil hardened to a melting point of 65° C. The criticality of the pressure drop across the nozzle is further shown in FIG. 3 which graphically illustrates the relationship between the reaction time required to 55 Blend L was a 50:50 mixture by weight of palm oil achieve complete randomisation and pressure drop. The hardened to a melting point of 58' C. and palm kernel oil employed was a sunflower blend and the catalyst a oil hardened to a melting point of 39 C. 1:2:3 solution of NaOH:glycerine:water at the various Different minimum amounts of NaOH in a 1:2:3 cata NaOH concentrations with respect to oil as given on lyst solution are required for the different blends. In the figure. The interesterification temperature was 125' 60 general however 0.05 to 0.1 wt % NaOH in a 1:2:3 C. and the drying pressure 4 mb. solution is required for complete randomisation to oc Table VIII below further illustrates the decrease in cur. Experiments were performed to determine tint ie reaction time with increasing pressure drop across the the time required to effect complete randomisation, as a spray nozzle. The blend employed was a neutralised and function of the amount of catalyst employing an intere bleached blend of 55 parts rapeseed oil hardened to a 65 sterification temperature of 125 C. and a drying pres melting point of 41 C. and 45 parts coconut oil having sure of 4 mb and using a 1:2:3 NaOH:glycerine:water an ffa of 0.1%. The catalyst was a 1:2:3 solution of solution. NaOH:glycerine:water and a constant pressure of 5mb The results are given in Table X. 4,585,593 11 12 TABLE X TABLE XIII FLOW FFA GLY- NaOH: RUN % NaOH RATE INT RUN IN CEROL NaOH DOSED NUMBER (ON OIL) OL (kg/h) (min) NUM. OIL DOSED DOSED EQUIV, INT 40 0.07 Batch O 100 20 5 BER (%) (%) (%) (%) (min) 7% INT 41 0.10 f 100 16 67 0.5 0.10 0.11 0.044 3 O 42 0.14 100 12 68 0.5 0.10 0.12 0.054 3 30 43 0.07 y 135 12 69 0.5 0.0 0,131 0,064 3 35 44 0.0 f 135 9 70 0.03 0.4 0.04 0.036 6 10 45 0.4 FF 135 6 71 0.03 0.4 0.05 0.046 6 290 46 0.10 60 30 O 72 0.03 0.14 0.06 0.056 3 290 4. 0.14 t 60 20 73 0.5 0.14 0.110 0.043 3 290 48 0.06 Batch F 195 14 74 0.5 0.14 0,121 0.054 l 290 49 0.08 t 95 8.2 50 0.08 Batch B OO 6 *% NaOH corrected for the FFA in the oil on an equivalent basis, 51 0.14 f 00 s3 15 Table XIII further illustrates the decrease in reaction time achieved on increasing the glycerine content in the The results given in Table X indicate that the intere catalyst solution. sterification time decreases with an increase in NaOH concentration with respect to the oil. EXPERIMENT 5 Experiments were performed on Batch. A to deter 20 Experiments were performed to illustrate the depen mine reaction time (tin) required to achieve complete dency of the reaction time required to achieve complete randomisation as a function of catalyst composition. randomisation on the interesterification temperature. The results are given in Table XI. The results are given in Table XIV. TABLE XI FLOW CATALYST DRYING RUN RATE SOLUTION % NaOH T PRESSURE INT NUMBER (kg/h) (NaOH:gly:H2O) (ONOIL) (C) (mb) (min) % INT 52 60 1/2/7 0.4 125 17 290 53 t 1A2/3 0.4 125 14 290 54 y F. 1/2/7 0.14 50 S3 290 55 Af 1/2/3 0,4 50 s3 290

TABLE XIV Runs 52 and 53 show a decrease in tint as the concen-35 FLOW tration of NaOH in the catalyst increases. RUN % NaOH T RATE INT Experiments were carried out on batch G, which NUMBER (ON OIL) (C) OIL (kg/h) (min) contained 0.18 wt % free fatty acid, to determine the 75 O.08 25 Batch A 60 22 is optimum catalyst composition for interesterification. In 76 0.08 135 f 60 4 it each run a drying pressure of 4 mb, an interestification 40 77 0.08 150 f 60 3 ...temperature of 125 C. and a throughput of 84 kg/h were 88: : Blend M 28 employed.

The results are given in Table XII. Oil1 blendbe M WaS a ixtXie Of72 A. W.wt %Zola lard anda 28 Wwit TABLE X 45% rapeseed oil. 86.5ion % NAOH % tNT The results illustrate the general trend of decreasing s reaction time with increase in temperature as well as the BER (NaOH/gly/H2O) (ON OIL) INTEREST (min) variation of reaction time between different oil blends. 56 1/1.7/3 0.12 80 32 57 1/1.7/3 0.10 is 10 32 EXPERIMENT 6 58 1/1.7/3 0.08 as 10 32 50 59 1/2/3 0.12 290 32 The beneficial effect with regard to reaction time of 60 1/2/3 0.10 85 32 including free fatty acid in the reaction mixture is illus 3. 22 8. -8 trated graphically in FIGS. 4 and 5. 63 1/2.5/3 0,12 290 32 Each interesterification run illustrated in FIG. 4 was 64 1/2.5/3 0.10 70 32 55 performed at an interesterification temperature of 125 65 1/2.5/3 0.08 is 0 32 C. and a drying pressure of 4 mb at a throughput of 120 66 A2.5/3 0.06 is 10 32 kg/h. In each case the catalyst employed was a 1:2:3 mixture of NaOH:glycerine:water, the NaOH concen The optimum catalyst composition in runs 56 to 66 tration being 0.075 wt % with respect to the oil for would appear to be a 1:2:3 mixture. The more relevant 60 batch A and 0.096 wt % for batch A including 0.3 wt % parameter was taken to be the amount of NaOH rather oleic acid. The higher NaOH concentration was re than the reaction time. quired in the latter case to neutralise the additional free The results given in Table XIII below illustrate the fatty acid present. Interesterification occurred more possibility of reducing the NaOH:H2O ratio to 1:2 when quickly in the presence of the oleic acid. the interesterification temperature is 145° C. The oil 65 Batch B was employed in each interesterification run used was blend H with varying FFA content. The pres graphically displayed in FIG. 5. In each case however sure in the dryer was 5 mbar and the pressure accross a varying amount of free fatty acid (oleic acid) and the spray nozzle 4 bar. NaOH was included. For the addition of 0.2%, 0.4% 4,585,593 13 14 and 0.6% free fatty acid respectively the NaOH con 5. Process according to claim 1 wherein the oil con centrations employed were 0.087, 0.120 and 0.148 wt % tains between 0.2 and 1.0 wt % free fatty acids with with respect of the oil in a catalyst solution containing respect to the oil. 0.174 wt % glycerine (on oil). An interesterification 6. Process according to claim 5 wherein the oil con temperature of 125 C. was employed in each run. A tains up to 0.6 wt % free fatty acids with respect to the more rapid rate of interestrification was found with the oil. higher free fatty acid content. 7. Process according to claim 1 wherein the oil and catalyst mixture is subjected to a pressure drop across EXPERIMENT 7 the spray nozzle of at least 2b. The effect of monoglycerides in the reaction mixture 10 8. Process according to claim 7 wherein the pressure is illustrated in FIG. 6 which is a plot of monoglyceride drop is at least 4b. concentration (ordinate) against reaction time required 9. Process according to claim 1 wherein the pressure to achieve complete randomisation. In each case the oil in the low pressure chamber is less than 20 mb. was batch B and the catalyst employed was as 1:2:3 10. Process according to claim 9 wherein the pressure NaOH:glycerine:water mixture giving a 0.096 wt % 15 in the chamber is less than 10 mb. concentration of NaOH on oil. The flow rate was 100 11. Process according to claim 1 wherein contact kg/h, the drying pressure was 4 mb and the interesterifi time between the streams prior to step (ii) is less than 20 cation temperature was 125 C. The plot shows an in seconds. verse relationship between monoglyceride content and 12. Process according to claim 11 wherein the said reaction time. 20 contact time is less than 5 seconds. 13. Process according to claim 11 wherein the EXPERIMENT 8 contact time is less than 1 second. 14. Process according to claim 1 wherein the intere Experiments were performed to determine the effect sterification is performed at a temperature between 100' on the interesterification rate of the presence of a dia 25 and 160 C. cylglycerol (1,3 distearate). Batch B was employed 15. Process according to claim 14 wherein the intere including firstly 0 wt %, secondly 1.5% and thirdly sterification is performed at a temperature between 125' 3.0% of added diglyceride. In each case 0.6 wt % of a and 150 C. catalyst solution was employed comprising a 1:2:3 mix 16. Process according to claim 14 wherein step (ii) is ture of NaOH:glycerine:water, the flow rate of the 30 performed within the temperature range employed for catalyst solution into the oil was 0.6 kg/h and the intere step (iii). sterification temperature was 125 C. 17. Process according to claim 16 wherein step (ii) is The results are illustrated graphically in FIG. 7. Al performed at a temperature approximately the same as though the effect on the interesterification rate of in that employed for step (iii), creased diglyceride is less than that achieved by the 35 18. Process according to claim 1 wherein the catalyst addition of monoglyceride, the graph does illustrate a solution comprises sodium hydroxide/glycerine/water beneficial effect due to the presence of diglyceride. in weight ratios in the range of from 1/2/3 to 1/2/7. We claim: 19. Process according to claim 1 wherein the alkali 1. A process for the interesterification of a triglycer metal hydroxide is selected from the group comprising ide oil employing a catalyst solution comprising a mix lithium hydroxide, sodium hydroxide, potassium hy ture of water, an alkali metal hydroxide and glycerine, droxide, and mixtures thereof. characterized by performing the process as a continu 20. Process according to claim 1 wherein the catalyst ous process comprising: contains, with respect to the oil, at least 0.03 wt % (i) bringing together streams comprising respectively sodium hydroxide. the oil and the catalyst solution to form a confluent 45 21. Apparatus for the interesterification of a triglycer stream; ide oil employing a catalyst solution comprising a mix (ii) passing the confluent stream of the oil and catalyst ture of water, an alkali metal hydroxide and glycerine solution through a spray nozzle into a low pressure characterised in that the apparatus comprises, in series, chamber to form a homogenized mixture of the oil inlet lines arranged to bring in use the catalyst solution and the catalyst solution by subjection to energetic 50 and oil respectively into contact with each other, means shear and to reduce the water content of the ho adapted to homogenise the catalyst solution and oil, mogenized mixture so as to allow formation of an means adapted to remove water from the homogenised active catalyst component; and mixture and a reactor adapted to maintain the mixture at (iii) holding the resulting mixture at a temperature a temperature for interesterification to occur. sufficient to cause interesterification. 55 22. Apparatus according to claim 21 wherein the 2. Process according to claim 1 wherein the water means adapted to homogenise the catalyst solution and content of the mixture is reduced to less than 0.03 wt % oil and the means adapted to remove water from the with respect to the total weight of the mixture. homogenised mixture are combined and are provided 3. Process according to claim 1 wherein the water by a spray drying nozzle. content of the mixture is reduced to less than 0.01 wt % 23. Apparatus according to claim 22 wherein the with respect to the total weight of the mixture. means adapted to homogenise the catalyst solution and 4. Process according to claim 1 wherein the oil con oil comprise a static mixer. tains not more about 2 wt % monoglycerides. k . x k k

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