JP3013451B2 - Method for producing sucrose fatty acid ester - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing sucrose fatty acid esters (hereinafter abbreviated as SE). More specifically, the present invention provides a method for preparing a reaction mixture produced by a solvent method, wherein SE and unreacted sucrose, a solvent, an inorganic salt and / or
Alternatively, the present invention relates to a method for efficiently separating an organic acid salt (hereinafter, these may be collectively referred to as a salt).

[0002]

2. Description of the Related Art SE is a nonionic surfactant useful as an edible dispersant, emulsifier or detergent. Conventionally, as a method for producing the same, transesterification between sucrose and a fatty acid ester such as fatty acid methyl in a solvent such as N, N-dimethylformamide or dimethyl sulfoxide (hereinafter abbreviated as DMSO) in the presence of an alkali catalyst. (Japanese Patent Publication No. 35-13102).

[0003] The reaction mixture obtained by the above method is
It contains a solvent, unreacted sucrose, an alkali catalyst and the like in addition to SE. To separate SE from this mixture,
Usually, after neutralization and deactivation of the catalyst by adding an acid to the reaction mixture, the solvent is partially distilled and then extracted with an organic solvent such as hexane, butyl alcohol, methyl ethyl ketone, methyl isobutyl ketone and water. Treatment and separation of the organic phase mainly by transferring SE into the organic solvent phase and the unreacted sucrose, the reaction solvent and the salt into the aqueous phase, and distilling off the organic solvent from the organic solvent phase mainly containing SE A method of recovering SE has been proposed.
(For example, JP-B-48-21927, JP-B-48-350)
49, JP-A-50-29417, JP-A-50-1307
12) It is important as an industrial production method and an economical operation method that the unreacted sucrose and the reaction solvent recovered in the aqueous phase are distilled and removed from water and then used again as a raw material for producing SE. However, in the extraction treatment operation step using an organic solvent and water, a salting-out agent such as an organic acid salt must be added in order to obtain good liquid separation properties (JP-A-50-130712). The sucrose recovered in the aqueous phase has salt accumulation. When the recovered sucrose is used again as a raw material for producing SE as it is after removing water by distillation, the method is a problem for economical operation, such as the transesterification reaction rate being delayed due to the effect of accumulated salts. .

[0004]

SUMMARY OF THE INVENTION The present invention recovers sucrose without salt accumulation from an SE production reaction mixture,
The present invention provides an industrial production method and an economic operation method used as production raw materials.

[0005]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to solve the above-mentioned problems, and as a result, water and a reaction solvent were separated from an aqueous phase separated by a conventional method using an organic solvent and water. The object was achieved by concentrating and removing, mixing the obtained recovered mixture with alcohol, separating and recovering unreacted sucrose free of salt as a solid, and reusing it. That is, the present invention provides a method for producing a sucrose fatty acid ester by reacting sucrose with a fatty acid lower alcohol ester using dimethyl sulfoxide as a reaction solvent in the presence of an alkali, wherein the reaction mixture is mixed with an organic solvent and water, Next, the organic solvent phase containing the sucrose fatty acid ester and the aqueous phase containing the unreacted sucrose, salt and dimethyl sulfoxide are separated, and the organic solvent is removed from the organic solvent phase obtained in the step to recover the sucrose fatty acid ester. ,
The recovered mixture obtained by concentrating and removing water and dimethyl sulfoxide from the aqueous phase obtained in was mixed with alcohol, and then separated into an alcohol phase containing salts and dimethyl sulfoxide and a solid phase containing unreacted sucrose, and obtained by A method for producing a sucrose fatty acid ester, wherein the solid phase is reused in the next reaction system.

The fatty acid lower alcohol ester in the present invention has 6 to 30 carbon atoms, preferably 12 to 22 carbon atoms.
Saturated or unsaturated fatty acids (for example, saturated fatty acids such as caproic acid, capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, behenic acid; linoleic acid,
Esters of unsaturated fatty acids such as oleic acid, linoleic acid, erucic acid, and ricinoleic acid) and lower alcohols having 1 to 6 carbon atoms (such as methanol, ethanol, propanol, and butanol) can be mentioned. Such lower alcohol esters may be used as a mixture of two or more. The fatty acid lower alcohol ester is generally used in an amount of 0.1 to 20 mol, preferably 0.2 to 20 mol per mol of sucrose.
Use 8 moles.

As a reaction solvent in the present invention, DMSO is used in view of thermal stability, solubility in sucrose and safety. The amount of the solvent to be used is generally 20 to 150% by weight, preferably 50 to 80% by weight, based on the total charged amount of sucrose and fatty acid lower alcohol ester. As the alkali catalyst in the present invention, an alkali metal hydride, an alkali metal hydroxide, an alkali metal salt of a weak acid, or the like is effective, and an alkali metal carbonate (eg, potassium carbonate) is particularly preferable.

The acid used for neutralizing and deactivating the catalyst in the present invention includes inorganic acids such as nitric acid, sulfuric acid, hydrochloric acid and phosphoric acid, formic acid, acetic acid, propionic acid, oxalic acid, succinic acid, and the like.
Organic acids such as benzoic acid, citric acid, lactic acid, and higher fatty acids having 8 to 22 carbon atoms are also included. Of these,
Citric acid or lactic acid is particularly preferred from the viewpoints of corrosiveness to equipment materials, solubility in water, and safety as a food additive.

In the present invention, an organic solvent and water are mixed with the reaction mixture after the transesterification reaction, and liquid-liquid extraction is performed. Here, although not essential, it is preferable to concentrate and remove DMSO from the reaction mixture before the liquid-liquid extraction from the viewpoint of reducing the amount of the organic solvent and water required for the extraction. Removal of DMSO is usually accomplished by adding DMSO in the reaction mixture.
The concentration may be reduced to 5 to 60% by weight, preferably 10 to 50% by weight. Excessive removal of DMSO will increase the viscosity of the concentrated mixture, which will be inconvenient for subsequent handling.

[0010] The liquid-liquid extraction in the present invention can be performed by a centrifugal force in addition to a mixing type using centrifugal force, in addition to a bedside countercurrent contact device utilizing a difference in specific gravity of two phases, or a system in which mechanical stirring or pulsation is applied thereto. It is selected from a countercurrent method such as a potbilnyak centrifugal extractor that performs separation, and a cocurrent method such as an orifice tower and an ejector. Usually, a countercurrent method is adopted, and a countercurrent multistage extraction method is preferable as an industrial method from the viewpoint of distribution efficiency and water usage. The organic solvent used for the liquid-liquid extraction of the reaction mixture in the present invention is usually hexane,
n-butanol, isobutanol, methyl ethyl ketone, methyl isobutyl ketone, etc .;
Butanol, isobutanol, and the like. In the liquid-liquid extraction, the salting-out agent may not be added, but is preferably added for stable operation. The salting-out agent to be added is preferably the same as that produced when the catalyst is neutralized and deactivated, and citrate or lactate is preferred from the viewpoints of stability as a food additive and formation of an interface during extraction.

The temperature of the liquid-liquid extraction operation in the present invention is generally lower than the boiling point of the organic solvent under atmospheric pressure, preferably 40 to 80 ° C. The amount of the organic solvent used is usually 0.5 to 20 parts by weight based on 1 part by weight of SE in the reaction mixture.
Parts by weight, preferably 1 to 10 parts by weight. The usage ratio of the organic solvent to water is generally 0.05 to 10 parts by weight of water, preferably 0.2 to 2 parts by weight, based on 1 part by weight of the organic solvent. The organic solvent is removed from the organic solvent phase obtained by the liquid-liquid extraction in the present invention to recover SE. The SE thus obtained can be used for general use as it is, but it is preferable to further purify the SE for use as a food additive. That is, it is preferable to remove a trace amount of the organic solvent by performing a steam treatment. The purified SE containing water after the steam treatment is concentrated and dried to produce a purified SE.

The aqueous phase after the liquid-liquid extraction in the present invention contains unreacted sucrose, DMSO and salts. After concentrating and removing water and DMSO from the aqueous phase, the process proceeds to a step of further removing salts and separating and recovering only unreacted sucrose. First, water is distilled off from the aqueous phase, and if necessary, DM
SO concentration removal is performed. In terms of the stability of unreacted sucrose,
It is preferred to distill under reduced pressure, first with water and then with DM
SO is distilled off. Since water is inconvenient in the next step of adding sucrose by adding alcohol, it is necessary to remove water as much as possible. Following the evaporation of water, DM
When the SO is concentrated and removed, the concentration of water in the recovered mixture is usually about 1% by weight or less due to the boiling point. DMSO
Similarly, when concentration removal is unnecessary, the concentration of water in the recovered mixture is usually 1% by weight or less, preferably 0.1% by weight.
Adjust so as to be not more than% by weight. As for the concentration and removal of DMSO, it is preferable to remove as much as possible in the same manner as in the case of water.However, if the entire amount is removed, the viscosity of the recovered mixture is increased, and handling becomes inconvenient. The DMSO concentration is 5 to 50% by weight, preferably 10 to 30% by weight. However, D from the reaction mixture
If the amount of MSO removed is sufficiently large, DM in the recovered mixture
The SO concentration may be appropriate from the beginning, and in such a case, it is not necessary to concentrate and remove DMSO.

In this way, water and, if necessary, DMS
The recovered mixture obtained by removing O is then mixed with alcohol. The amount of alcohol used depends on this recovered mixture 1
1 to 10 parts by weight, preferably 2 to 7 parts by weight,
Parts by weight. Alcohol may be added to the recovered mixture containing unreacted sucrose, but the addition of the recovered mixture to alcohol is more conservative in terms of the recovery of unreacted sucrose and the separation of unreacted sucrose and salts. preferable. The method of adding the recovered mixture to the alcohol is arbitrarily selected from batch, intermittent, and continuous addition, but continuous addition is preferred from the viewpoint of the recovery rate of unreacted sucrose and separation of unreacted sucrose from salts. The mixing temperature with the alcohol is usually selected from temperatures below the boiling point of the alcohol at atmospheric pressure, such as the viscosity of the recovered mixture,
From the viewpoint of the recovery rate of unreacted sucrose, separation of unreacted sucrose and salts, stability of sucrose, and the like, it is usually selected from the range of 30 to 100 ° C, preferably 40 to 80 ° C. As the alcohol for sucrose precipitation in the present invention, a lower alcohol is usually used. Examples of preferred lower alcohols include methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol and the like. During the production reaction of SE, a lower alcohol derived from a fatty acid lower alcohol ester as a raw material is produced as a reaction by-product. Therefore, the method of using the lower alcohol as the alcohol for sucrose precipitation of the present invention is particularly industrially advantageous. It is.

In the present invention, the solid-liquid separation, that is, the separation of the solid phase containing unreacted sucrose and the alcohol phase containing salt is performed by filtration using a filter, a strainer, or the like, or by pressing or centrifuging using a press. Arbitrarily selected. Since the main component of the solid phase recovered in this step is unreacted sucrose, it is reused as a raw material for producing SE. The unreacted sucrose thus recovered contains almost no salt, and the transesterification reaction is not delayed even if it is reused repeatedly in the next reaction system.

On the other hand, the alcohol phase is a mixture containing alcohol as a main component, DMSO and a salt. A salt is recovered from the alcohol phase by removing alcohol and DMSO, and a corresponding acid can be recovered from the salt. First, alcohol is recovered by distillation treatment, and it is industrially advantageous and preferable to reuse it for unreacted sucrose precipitation. Next, DMSO is recovered, which is preferably reused as a reaction solvent. The recovery of DMSO is carried out by a normal distillation treatment. However, when the treatment temperature is high, a small amount of sucrose contaminated is easily decomposed, and the recovered DMS
Since O is contaminated by sucrose decomposition products, it is preferable to perform the reaction under reduced pressure. For example, the use of a horizontal thin film evaporator disclosed in JP-A-58-4038 is more preferable in terms of the DMSO recovery rate, and the salt is recovered to a concentrate discharged from the horizontal thin film evaporator.

The above-mentioned recovered salt in the present invention is further preferably treated with an ion exchange resin and recovered as an acid corresponding to the salt, as an economical production method. The concentrated recovered salt after the removal of DMSO is preferably diluted with water and treated with an ion exchange resin. The salt concentration in the aqueous solution is usually 0.1 to 50% by weight, preferably 1 to 30% by weight. As the ion exchange resin treatment temperature in the present invention,
It is usually 5 to 100 ° C, preferably 20 to 70 ° C.

In the method for recovering the above-mentioned acid in the present invention, an aqueous solution containing a salt is treated with a basic anion exchange resin, the salt is converted into the corresponding acid, and the salt is retained on the exchange resin. And an aqueous solution containing DMSO. Next, when the acid held in the anion exchange resin is passed through an aqueous alkali solution, the acid is separated again from the exchange resin as an aqueous salt solution. However, in this aqueous solution, since the alkali for regeneration is discharged together with the salt, it is then treated with an acidic cation exchange resin to adsorb and remove the alkali, thereby purifying the corresponding acid in a purified form. Collected.

The ion exchange resin used in the present invention includes those having various chemical structures and physical structures. As the physical structure, either a gel type or a porous type resin can be used. Further, a wide range of the degree of crosslinking is applied. The following are typical examples of preferable ion exchange resins, but the resins used in the present invention are not limited to these. Anion exchange resin: a resin in which a quaternary ammonium group or a primary to tertiary amine is bonded as an exchange group to a polymer substrate that has been three-dimensionally polycondensed. Specific products include, for example, Mitsubishi Kasei Co., Ltd. Diamond ion SA, PA, W
A series and the like. In the present invention, the PA series, which is a porous styrene-based strongly basic anion exchange resin, is preferred in terms of exchange rate, decolorization, regeneration efficiency, and the like. Cation exchange resin: a resin in which a sulfonic acid group, a carboxylic acid group, or the like is bonded as an exchange group to a polymer substrate that has been three-dimensionally polycondensed, and specific products such as those manufactured by Mitsubishi Kasei Co., Ltd. Diaion SK, PK, WK series, and the like. In the present invention, the SK series, which is a styrene-based strongly acidic cation exchange resin, is preferred in terms of exchange rate, regeneration efficiency and the like.

[0019]

The present invention will be described in detail with reference to the following examples.
Limited by these examples without exceeding the gist.
It is not something to be done. Reference example (conventional method, using new sucrose) Reaction / concentration process Reaction of 30 liter capacity with sufficiently dried stirrer
In a vessel, 3743 g of sucrose and DMSO1 as a solvent were used.
Charge 1.5 kg and boil the solvent under a pressure of 20 mmHg.
And the solvent vapor is cooled to condense and reflux, and
After a minute, part of the solvent was distilled off, and the system was dehydrated. DMSO
When the amount of distillate reached 1 kg, the distillation was stopped.
When the water content was measured, the water content was 0.06% by weight.
Met. Next, 12 g of anhydrous potassium carbonate and
529.9 g of methyl lumitate, methyl stearate 2
Add 27.1 g and boil DMSO at 20 mmHg.
Meanwhile, the steam is cooled, concentrated and refluxed.
While distilling off the generated methanol outside the reaction system,
I responded. The reaction temperature is 90 ° C on average, and fatty acid methyl 99
The time to reach% conversion was 2.8 hours. Reaction is 3 o'clock
I went there. After completion of the reaction, 32 g of a 50% aqueous solution of lactic acid is added.
And the catalyst was deactivated. Gel permeate the reaction mixture
Analysis of the SE composition
Is monoester 80.7%, diester 17.0%,
Triester 2.3% (area percentage)
Methyl palmitate and sulfur
Fatty acid methyl calculated from the residual amount of methyl theate
The conversion was found to be 99.6%. Reactor
The composition of the reaction mixture extracted was the unreacted sucrose 19.
9% by weight, SE 9.7% by weight, salt 0.15% by weight, DM
SO was 70.2% by weight. Anti-reactor taken out of the reactor
15 kg of the reaction mixture was transferred to a horizontal thin film evaporator (heat transfer area 0.1
m ^Two, Manufactured by Hitachi, Ltd.)
With a temperature of 110 ° C and a pressure of 10mmHg, supply of 7kg / Hr
When the liquid was passed at the feed rate, the amount of discharged liquid was 5.4 kg.
Was. As a result of composition analysis of the concentrated reaction mixture, sucrose 49.5 was obtained.
Wt%, SE 24.1 wt%, salt 0.4 wt%, DMS
O was 26.0% by weight. Liquid-liquid extraction step The above concentrated reaction mixture was treated with 10% aqueous isobutanol 1
Dissolved in 5.5 kg. Next, add 15.5 kg of pure water
Unreacted sucrose and DMSO in SE-isobutanol solution
To the aqueous phase by repeatedly using a 2-liter separating funnel.
Issued. Further, potassium lactate 1 was added to the SE-isobutanol solution.
Unreacted sucrose remaining in traces by adding pure water containing 500 ppm
And DMSO were recovered. The flash phase is on the water side
After removing the water using a sucrose, unreacted sucrose-DMS
The O solution was collected. The salt concentration in the recovered unreacted sucrose is
It was 1.8% by weight.

Comparative Examples 1 to 4 (Repeated reaction by conventional method) Unreacted sucrose (2000) recovered from the aqueous phase side in Reference Example
g) The DMSO solution was reused, and 1743 g of new sucrose was added to obtain a sucrose raw material. The raw material had the same composition as in the reference example, and the reaction, concentration, liquid-liquid extraction, sucrose-
The collection of the DMSO solution and the reuse with the addition of new sucrose were repeated four times to produce SE, and the time to reach 99% conversion of fatty acid methyl was measured. The results are shown in Table 1 below.
Example 1 (Recovery of unreacted sucrose, removal of salt) Unreacted sucrose-DMSO solution (the salt concentration in sucrose 3.0% by weight) after the first reaction (Comparative Example 1) of the comparative example was repeated.
Was used to separate unreacted sucrose and salt. DMSO is concentrated and removed from the unreacted sucrose-DMSO solution, and DMS
The O concentration was 23% by weight. After charging 3 kg of methanol into a 5 liter table-top type kneader with a jacket (PNV-5 manufactured by Irie Shokai Co., Ltd.) and maintaining the temperature at 40 ° C., 750 g of the recovered sucrose-DMSO solution at 60 ° C. was added to 30 ml.
And the mixture was mixed for 60 minutes after the completion of the addition. Next, a liquid phase and a solid phase in the kneader were separated by using a 1-liter pressure filter filled with filter paper having a retention particle diameter of 1 μm. The results are shown in Table 2 below. The salt concentration of the recovered solid phase in unreacted sucrose was 0.03% by weight.

Example 2 (Recovery of unreacted sucrose, removal of salt) Unreacted sucrose-DMSO solution after the fourth reaction (Comparative Example 4) of the comparative example (salt concentration of 5.8% by weight in sucrose) %)
The same operation as in Example 1 was performed except that was used. The results are shown in Table 3 below. The salt concentration of the recovered solid phase in unreacted sucrose was 0.5% by weight.

Example 3 (Reaction using recovered unreacted sucrose according to the method of the present invention) Methanol was removed from the solid phase of Example 2 to give unreacted sucrose (99.4% by weight of sucrose, salt 0.1%). 5% by weight), and transesterification was carried out with the same preparation composition as in Reference Example except that sucrose material was used without supplying new sucrose. As a result, the time to reach the 99% conversion of fatty acid methyl was 2.8.
Hr, which was confirmed to be equivalent to the reaction rate using the new sucrose.

Examples 4 to 7 (Repeated reaction according to the process of the present invention) From the solid phase precipitated by adding alcohol in Example 2,
2000g of unreacted sucrose recovered by removing methanol
Was reused, and 1743 g of new sucrose was added to obtain a sucrose raw material. Using the sucrose raw material, a reaction, concentration, liquid-liquid extraction, recovery of a sucrose-DMSO solution, and removal of salts by addition of alcohol were performed so that the raw material had the same composition as in the reference example. Subsequently, reuse with addition of new sucrose was repeated four times to produce SE, and the time to reach 99% conversion of fatty acid methyl was measured. The results are shown in Table 4 below. As can be seen from Examples 3 to 7, in comparison with Comparative Examples 1 to 4, the method of the present invention suppresses the accumulation of salts even when reused unreacted recovered sucrose is repeatedly used. Approximately equivalent fatty acid methyl 99% conversion times are obtained.

Example 8 (Recovery of Acid) The methanol was removed from the liquid phase of Example 2 to recover trace amounts of sucrose, salt and DMSO. Further, using a rotary evaporator (operating conditions: 90 ° C., 1 mmHg),
The composition after removing the MSO was sucrose 47% by weight, salt (potassium lactate) 48% by weight, and DMSO 5% by weight.
This is diluted with pure water to form an aqueous solution having a salt concentration of 10% by weight.
It was subjected to ion exchange resin treatment. Ion exchange resin has an inner diameter of 5
A jacketed glass column having a height of 80 cm and a height of 80 cm was filled with 800 ml of PA-308 (strongly basic anion exchange resin) manufactured by Mitsubishi Kasei Co., Ltd., and kept at 30 ° C. Next, 30
500 g of the above aqueous solution at a temperature of 2 ° C. was passed at a rate of 2400 ml / Hr. After passing the whole amount, 500 ml of pure water was passed in the same manner to wash. By the above operation, lactic acid is adsorbed on the PA-308 resin,
Lactic acid was separated from sucrose and DMSO. 500 ml of 5% by weight potassium hydroxide aqueous solution is added to PA-308 adsorbing lactic acid.
The solution was passed through the tank to regenerate, and simultaneously, potassium lactate was discharged. Since the discharged potassium lactate aqueous solution contains potassium hydroxide at the same time,
Next, a strongly acidic cation exchange resin (manufactured by Mitsubishi Kasei Corporation, SK
-1B). As the operating conditions, the same glass column as described above was used after filling with 800 ml of SK-1B resin, and the solution was passed at 30 ° C. at 2400 ml / Hr to obtain an aqueous lactic acid solution. The recovery rate of lactic acid analyzed by the potentiometric neutralization titration method was 70% of the charged amount (total amount of the acid added for the catalyst neutralization and the amount added as the salting-out agent), and it was confirmed that the lactic acid was recovered in high yield. Was.

[0025]

[Table 1]

[0026]

[Table 2]

[0027]

[Table 3]

[0028]

[Table 4]

[0029]

According to the method of the present invention, high-purity unreacted sucrose is separated and recovered from the reaction mixture, reused in the reaction, and repeatedly used to economically and efficiently use sucrose fatty acids. Esters can be produced, and the transesterification reaction is not delayed even when reused. In addition, since organic acids / inorganic acids can be economically separated and recovered, they can be reused.

[Brief description of the drawings]

FIG. 1 is a simple flowchart showing an example of the process of the present invention.

Claims (6)

(57) [Claims] 1. A method for producing a sucrose fatty acid ester by reacting sucrose with a fatty acid lower alcohol ester using dimethyl sulfoxide as a reaction solvent in the presence of an alkali, wherein the reaction mixture is mixed with an organic solvent and water, An organic solvent phase containing a sucrose fatty acid ester,
Separated into an aqueous phase containing unreacted sucrose, salts and dimethylsulfoxide, the organic solvent was removed from the organic solvent phase obtained in and the sucrose fatty acid ester was recovered, and water and dimethylsulfoxide were recovered from the aqueous phase obtained in. The concentrated recovered mixture is mixed with alcohol, then separated into an alcohol phase containing salts and dimethyl sulfoxide, and a solid phase containing unreacted sucrose, and the solid phase obtained in is reused in the next reaction system A method for producing a sucrose fatty acid ester, comprising: 2. The production method according to claim 1, wherein 1 to 10 parts by weight of an alcohol is mixed with 1 part by weight of a recovered mixture obtained by concentrating and removing water and dimethyl sulfoxide from the aqueous phase. 3. The method according to claim 1, wherein the alcohol is a lower alcohol. 4. The method according to claim 1, wherein the alcohol is methanol, ethanol,
3. The method according to claim 1, wherein the method is selected from n-propanol, isopropanol, n-butanol and isobutanol. 5. A method for producing a sucrose fatty acid ester by reacting sucrose with a fatty acid lower alcohol ester using dimethyl sulfoxide as a reaction solvent in the presence of an alkali, wherein the reaction mixture is mixed with an organic solvent and water, An organic solvent phase containing a sucrose fatty acid ester,
Separated into an aqueous phase containing unreacted sucrose, salts and dimethylsulfoxide, the organic solvent was removed from the organic solvent phase obtained in and the sucrose fatty acid ester was recovered, and water and dimethylsulfoxide were recovered from the aqueous phase obtained in. The concentrated recovered mixture is mixed with alcohol, then separated into an alcohol phase containing salts and dimethyl sulfoxide and a solid phase containing unreacted sucrose, and the solid phase obtained in is reused in the next reaction system. A method for producing a sucrose fatty acid ester, comprising recovering an acid corresponding to a salt by treating the alcohol phase obtained in (1) and (2) with an ion exchange resin. 6. An alcohol-phase ion-exchange resin treatment, wherein an aqueous solution obtained by removing alcohol from the alcohol phase and then mixing with water is treated with an anion-exchange resin to adsorb an acid corresponding to a salt, Passing an aqueous alkali solution through the anion exchange resin to desorb the acid, obtaining a mixture of a salt and an aqueous alkali solution, treating the mixture with a cation exchange resin to adsorb the alkali, and recovering the acid. The production method according to claim 5, wherein