JP4335306B2 - Oil transesterification method - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for transesterification of fats and oils.
Background art Triglycerides are converted by enzymatic transesterification reaction between fats and oils and fatty acids or lower alcohol esters thereof (hereinafter referred to as "fatty acid esters") to increase the concentration of specific triglyceride molecular species. Modification of properties has been performed. However, since this reaction is an equilibrium reaction, a large amount of expensive raw material fatty acid ester or the like must be used when the target concentration is high, and the oil and fat after the reaction can be separated by means such as solvent separation to obtain the target concentration. Has been done.
However, solvent fractionation requires a large amount of equipment, which increases the cost. From the viewpoint of work safety, it is preferable not to use solvent as much as possible, and only the transesterification reaction is performed without solvent fractionation. It is ideal if the concentration of triglyceride can be increased efficiently.
As a method for improving the reaction efficiency of fatty acid esters and the like, a multi-stage transesterification reaction is conceivable, but if it is as it is, sufficient efficiency cannot be obtained even if the number of stages is increased. Also, isomerization occurs due to migration of triglycerides and diglycerides that occur during the distillation operation, and undesirable by-products are produced during the next reaction (isomer SSO is produced in the production of SOS-type hard butter using oleic fats and stearates) However, SSS is generated during the reaction of the next stage), so that there is a problem that separation of these by-products is necessary, color tone is deteriorated due to heat history, and oxidation deterioration stability is lowered.
On the other hand, in order to improve the reaction efficiency of fatty acid esters and the like in the multi-stage transesterification reaction, a method of supplying the fatty acid esters and the like used in the reaction as they are to the subsequent reaction (JP-A-5-219971) is also disclosed. The problems of by-products, color tone, and oxidative degradation are still not solved.
Moreover, although the method (Japanese Patent Publication No. 3-69516) which isolate | separates a fatty acid ester from a reaction liquid, hardens | cures, and circulates to a reaction liquid is also disclosed, it is not known to leave a specific fatty acid ester etc. with fats and oils.
Disclosure of the Invention (Problems to be Solved by the Invention)
It is an object of the present invention to obtain a transesterification method for efficiently increasing the concentration of the target triglyceride.
(Means for solving the problem)
As a result of diligent research on various transesterification methods, the present inventor has modified a conventional distillation method in which all of fatty acid esters and the like are distilled off in a multi-stage transesterification reaction, such as fatty acid esters liberated from triglycerides by reaction, etc. When the boiling point of the fatty acid is lower than the boiling point of the raw fatty acid ester or the like to be introduced into the triglyceride, the fatty acid ester or the like released from the triglyceride by the reaction is distilled off, but the raw fatty acid ester or the like to be introduced into the triglyceride is not distilled off. By performing simple distillation, the inventors have obtained the knowledge that it is possible to efficiently achieve a high concentration of the target triglyceride without performing fractionation, and the present invention has been completed.
That is, the present invention is a method of repeating a transesterification reaction of fats and oils with a fatty acid or a lower alcohol ester thereof and an enzyme as a catalyst, and a distillation step of removing the fatty acid or the lower alcohol ester thereof in multiple stages, This is a method for transesterification of fats and oils with the main purpose of selectively leaving fats and oils and raw fatty acids or lower alcohol esters thereof in the previous distillation step.
Kinds of raw material fats and oils and raw material fatty acid esters are subject to certain restrictions. That is, a combination of raw materials must be selected so that the fatty acid esters liberated from the raw oil and fat can be selectively distilled off as much as possible without distilling off the raw fatty acid esters and the like in the distillation step. Therefore, in general, it is necessary to select the fatty acid liberated from the triglyceride or the ester thereof by boiling so that the boiling point of the fatty acid or its ester is smaller than the boiling point of the starting fatty acid ester or the like to be introduced into the triglyceride.
Other than the above restrictions, there is no particular limitation, and various types can be used. Specifically, fats and oils include sunflower oil, high oleic sunflower oil, safflower oil, high oleic safflower oil, soybean oil, rapeseed oil, olive oil, palm oil, monkey fat, shea fat, coconut oil, palm kernel oil, etc. Examples include one or more mixed oils selected from animal oils such as vegetable oil, fish oil, beef tallow, pork tallow, and synthetic glycerides such as MCT and trilaurin. Examples of fatty acid esters include palmitic acid, oleic acid, and behenic acid. Examples thereof include esters of lower alcohols such as fatty acids having 12 to 24 carbon atoms and methyl or ethyl esters thereof.
The transesterification reaction is carried out using the above raw materials and the enzyme as a catalyst. A known method can be employed as the transesterification method. That is, an enzyme preparation in which an enzyme having transesterification activity such as lipase or a bacterial cell is immobilized by a known method can be used as a catalyst.
The reaction liquid is distilled by a known method so as to separate fatty acid esters and the like from fats and oils. In this invention, the distillation conditions are such that the raw fats and oils and the raw fatty acid esters remain selectively in the distillation step before the final stage. To do. Specifically, the distillation temperature is set so that the fatty acid or its ester liberated from the raw material triglyceride is distilled off as much as possible, and only the raw material fat and fat, the raw material fatty acid ester, etc. remain selectively and in large quantities. Good.
This temperature is preferably lower than the temperature at which all fatty acid esters and the like are distilled, particularly at a temperature of 210 ° C. or lower, which suppresses the formation of undesirable by-products such as high melting point components due to migration of triglycerides and diglycerides. In addition, since the heat history is reduced, it is possible to suppress deterioration in color tone and stability in oxidation deterioration. These effects appear more clearly as the chain length of the fatty acid such as the starting fatty acid ester to be introduced is longer, and is particularly remarkable when the chain length is 22 or more (22 to 24).
When most of the fatty acid ester, etc. liberated from the triglyceride is distilled off, the distillation is finished, and the reaction solution after the distillation is left as it is or, if necessary, a raw material fatty acid ester, etc. is added to the reaction solution at a temperature suitable for the reaction. Stage transesterification and distillation. When it is desired to obtain a higher concentration of triglyceride, the number of stages can be increased as necessary (further transesterification reaction-distillation is repeated).
After the final stage reaction, substantially all the fatty acid esters and the like are removed by ordinary distillation to obtain the target triglyceride.
By the above series of methods, the reaction efficiency of the raw material fatty acid ester and the like can be increased, and the concentration of the target triglyceride can be increased efficiently. In addition, the present invention does not require an oil / fat fractionation step such as solvent fractionation, and therefore can be said to be an excellent method from the viewpoint of safety.
Examples and Comparative Examples Hereinafter, the present invention will be described by way of examples. In the examples, "parts" and "%" represent weight standards.
[Example 1]
Dissolve 20 parts of commercially available lipase (Rhizopus nibeus origin: 3000 IU / ml) in 80 parts of cold water, mix well with 75 parts of Celite, and then dry the lipase to a moisture content of 2.0% or less over 4 days at 20 ° C. Obtained.
28 parts of high oleic sunflower oil and 72 parts of behenic acid ethyl ester were mixed, 2 parts of acid clay was added, stirred at 5 ° C. under reduced pressure for 5 minutes at 110 ° C. for 20 minutes, and then filtered to prepare a reaction substrate having a water content of 50 ppm or less.
The column was filled with 90 g of the above lipase agent, and the reaction substrate was passed through at 50 g / hr and 53 ° C., and then the reaction solution was collected and used as the first-step reaction solution. The distillation (51.4 parts) was selectively removed until substantially no ethyl oleate remained in a distillation flask under 2TORR vacuum and held at 206 ° C. Table 1 shows the fatty acid composition of the ester before distillation, the amount of distillation, and the ester remaining in the flask.
Next, 58.2 parts of behenic acid ethyl ester was added to 48.6 parts of the mixture of triglyceride and ethyl ester remaining in the flask, treated with white clay in the same manner as above, and passed through the column to obtain a second-stage reaction liquid. Under 2TORR vacuum, the temperature was held at 255 ° C. to completely remove the ester component. The reaction product has a BOB content of 62% and a BBB content of only 2.7%, and an automatic recovery function (when it is added to chocolate as a stable crystal, it is exposed to a temperature around body temperature so that the entire chocolate melts. After that, it was of a quality that can be used as a tempering accelerator having a function of returning to the original glossy chocolate. The color tone was 3.0 × 30 (value measured with a Robibond colorimeter using a 5 + 1/4 inch cell. The same applies hereinafter).
[Example 2]
30 parts of a palm oil high melting point fraction (PPP = 75%, POP = 25%) and 70 parts of oleic acid ethyl ester (prepared from high oleic sunflower oil) were mixed and dried in the same manner as in Example 1. A reaction substrate was prepared.
A transesterification reaction was carried out in the same manner as in Example 1 except that lipozyme (enzyme manufactured by Novo) was used as a commercially available lipase and the column flow temperature was 55 ° C., followed by 2 TORR vacuum in a distillation flask. Then, the mixture was held at 160 ° C. and 40 parts of ethyl ester was distilled off to leave a fraction of only oil and fat and ethyl oleate.
Next, 40 parts of oleic acid ethyl ester is added to 60 parts of the mixture of triglyceride and ethyl ester remaining in the flask, and the second stage reaction liquid is obtained by treating with clay and passing through the column in the same manner as in the first stage. The temperature was kept at 235 ° C. to completely remove the ester component. The reaction product had an OPO content of 45%, which was satisfactory in terms of color tone and oxidative deterioration stability (color tone = 1.0 × 10, AOM = 100 hr).
Example 3
A reaction substrate was prepared in the same manner as in Example 1 by mixing 50 parts of trilaurin (purity 98%, manufactured by Sigma) and 50 parts of stearic acid. A lipozyme (enzyme manufactured by Novo) was used as a commercially available lipase, the column passing temperature was 65 ° C., 5 g of lipase agent was packed in the column, and the substrate was passed at 3 g / hr. After performing the first stage transesterification, the distillate rich in lauric acid was removed by holding in a distillation flask at 150 ° C. under 2 TORR vacuum.
Next, 25 parts of stearic acid was added to 75 parts of the mixture of triglyceride and fatty acid remaining in the flask, and the clay was treated in the same manner as in the first stage to obtain a second stage reaction liquid. Then, under 2TORR vacuum, The fatty acid component was completely removed by holding at 250 ° C. The SLS (L is lauric acid) content in the reaction product was 53.5%, and the color tone and oxidative deterioration stability were satisfactory.
[Comparative Example 1]
The first stage reaction solution of Example 1 was distilled at 255 ° C. to completely distill off the ethyl ester, and then 72 parts of behenic acid ethyl ester was added to 28 parts of the triglyceride remaining in the flask, treated with white clay, and passed through the column. The second stage reaction liquid was obtained by holding the liquid and held at 255 ° C. under 2TORR vacuum to completely remove the ester component. Although the BOB content in this reaction product was 62%, the BBB content was as high as 5.1%, so that it was of a quality that was difficult to use as a tempering accelerator unless the high melting point component was separated and removed. Moreover, it was quite colored and was not preferable (color tone = 5.0 × 50).
[Comparative Example 2]
The same method as in Example 2 was carried out except that the first stage distillation was performed at 235 ° C. and 70 parts of ethyl oleate added newly to the reaction solution was used. Although the OPO content in the reaction product was 45%, it was inferior to the examples in terms of color tone and oxidative deterioration stability (color tone = 2.0 × 20, AOM = 70 hr).
〔effect〕
As described above, the examples require less use of fatty acid esters and the like than the comparative examples, and the generation of by-products is also suppressed. We were able to do it efficiently.
[Table 1]

Claims (4)

A method of repeating transesterification of fats and oils with a fatty acid or a lower alcohol ester thereof and an enzyme as a catalyst, and a distillation step for removing the fatty acid or the lower alcohol ester thereof in a multistage manner, in a distillation step before the final stage A method for transesterifying fats and oils, wherein the distillation temperature is set to 210 ° C. or lower and fats and fats and raw fatty acids or lower alcohol esters thereof are selectively left. The method for producing fats and oils according to claim 1, wherein the fats and oils are not fractionated at least between the transesterification step and the previous transesterification step. The method for transesterifying fats and oils according to claim 1, wherein the fatty acid constituting the raw fatty acid or its lower alcohol ester has 18 to 24 carbon atoms. The method for transesterifying fats and oils according to claim 1, wherein the fatty acid constituting the raw fatty acid or the lower alcohol ester thereof has 22 to 24 carbon atoms.