JP2688937B2 - Method for producing powdery sucrose fatty acid ester - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial applications]

The present invention mainly relates to an industrial production method of powdery sucrose fatty acid ester. More specifically, the present invention relates to a technique for industrially producing a high-quality powdery sucrose fatty acid ester without using an organic solvent for purification and recovering unreacted sugar in a reaction mixture. .

[Prior art]

(Background) At present, sucrose fatty acid esters (hereinafter abbreviated as “SE”) useful as surfactants are commercially available from sucrose and C _{8 to} C _22.
The higher fatty acid methyl ester of is reacted with a suitable catalyst in a solvent (dimethylformamide, dimethylsulfoxy, etc.) (solvent method: JP-B-35-13102), or sucrose can be obtained by using water without using a solvent. It is obtained by making a molten mixture with a fatty acid soap and then reacting it with a higher fatty acid methyl ester in the presence of a catalyst (water medium method: Japanese Examined Patent Publication No. 14485 / SHO). However, by any of these two synthetic methods, in addition to the target SE, unreacted sugar, unreacted fatty acid methyl ester, residual catalyst, soap,
It contains contaminants such as free fatty acids and volatiles, and those impurities whose content exceeds a specified amount must be removed before the product is formed. In particular, of the above contaminants, removal of the residual solvent (volatile matter) associated with the former solvent method is extremely important only for the recent regulations ( ^Note) . Note) According to the US FDA standard, the residual dimethyl sulfoxide allowable in SE is 2 ppm or less (Fed.Regist., 51
(214), 40160-1). Another important problem in industrial production of SE is the problem of recovering unreacted sugar. That is, as is well known,
The reaction rate of sucrose at the time of SE synthesis is low, and for example, even in the case of the dimethylformamide method, it does not reach 50% (Refer to Applicant Company 《Sugar Ester Story (1984)》 page 35), so there is no recovery of unreacted sucrose This industry is not established. Therefore, a large amount of organic solvent has been conventionally used for the dual purpose of removing residual reaction solvent from crude SE and recovering unreacted sugar.However, heavy use of such solvent is not suitable for industrial production of SE. , Brings the following significant disadvantages. Risk of explosion and fire. Explosion-proof electrical equipment provided above. Sealing of the production equipment provided above. The fire-resistant structure of the whole building prepared above. Above, due to rising fixed costs. Cost increase due to solvent wear. Negative effect due to residual solvent remaining in product SE. The negative impact on employee health, and the rise in fixed costs associated with the increase in the number of shifts to prevent it. Under these circumstances, there has been a pressing need in the art to develop a technology that makes the use of an organic solvent unnecessary during SE purification and sugar recovery. (Problems of the prior art) Therefore, a purification method which does not use an organic solvent has been conventionally investigated, and as a typical example, (1) a method for precipitating SE with an acidic aqueous solution (UK Patent 809,81
5 (1959)) (2) SE precipitation method using general neutral salt aqueous solution
−8850). However, as in the method (1), for example, when an aqueous hydrochloric acid solution is added to the reaction mixture, the SE immediately precipitates as soon as possible, but the unreacted sucrose is easily decomposed and converted into glucose and fructose. (0-5 ° C.), decomposition cannot be avoided. Therefore, it becomes difficult to recover and reuse the unreacted sugar. Also, as in method (2), SE is immediately precipitated even when an aqueous solution of a neutral salt such as salt or sodium sulfate is added to the reaction mixture. In this case, the decomposition of unreacted sugar does not occur, but the monoester, which is a useful component in SE, is dissolved in the aqueous phase side, causing not only a large loss but also high HLB It is an obstacle when you want to get SE. According to a more recent Japanese Patent Application Laid-Open No. Sho 51-29417, a mixed solution of water and a "purified solvent" (which is particularly called to distinguish it from the reaction solvent) is composed of a light liquid layer (upper layer) and a heavy liquid layer (lower layer). The property of phase separation is used. That is, generally a heavy liquid layer (lower layer)
Contains a large amount of water, and hydrophilic unreacted sugar, catalyst-derived salts, and the like are dissolved in the heavy liquid layer (lower layer).
On the other hand, since the light liquid layer (upper layer) contains a large amount of purified solvent, small polar substances such as SE, fatty acids and unreacted fatty acid methyl esters are dissolved in this light liquid layer. However, reaction solvents such as dimethyl sulfoxide also dissolve in the lower heavy liquid layer, but unfortunately also dissolve in the upper light liquid layer, so it is impossible to completely separate the reaction solvent by this method alone. It is. Therefore, a very large amount of a purified solvent is required only for removing a trace amount of the reaction solvent. Thus, in order to industrially enable the purification of crude SE with water, it is a major premise to develop a purification method in which the solvent is completely removed and the sugar and the product SE are not lost. Next, what should be further considered in order to industrially enable purification by water is a means for drying the water-containing SE accompanying the use of water as a purification solvent. That is, the water-containing SE to be dried here is usually
In general, those having a water content of 80% or more are in the form of an aqueous solution, and those having a water content of less than 80% are usually in the form of a slurry.
The water content of these SEs generally shows a sharp increase in viscosity from around 40 ° C and reaches the maximum value around 50 ° C, but when the temperature exceeds 50 ° C, the viscosity decreases sharply, exhibiting a very unique viscous behavior. (See page 108 above). Besides, it is practically impossible to simply evaporate the water by heating under vacuum because of the remarkable foaming property. If the heating temperature is high and the contact time with the heating element is long, SE causes decomposition, which not only causes strong coloring and caramelization, but also the acid value of fatty acids released by decomposition. Also rises (see Japanese Examined Patent Publication No. 37-9966). Especially at the end of evaporation of water, SE has a characteristic of softening point or low melting point (for example, the conversion point of sucrose monostearate is around 52 ° C, the difficulty of sucrose distearate is 110 ° C).
(Nearby), the SE itself has a tendency to hydrate the remaining water, which makes dehydration extremely difficult. In addition, the latent heat of vaporization of water is abnormally high (500K
cal / Kg · H ₂ O or more) and high evaporation temperature are also factors that make drying difficult. Therefore, for example, as another type of drying method, even when using a so-called flash type dryer that heats sludge and continuously supplies it to the vacuum chamber and discharges it, due to the large latent heat of water, it is sufficient. There are various difficulties associated with dehydration and drying, and even if you can overcome these difficulties, SE after dehydration and drying under vacuum is in a molten state, so after removing it from the dryer, It requires many steps of cooling by blowing cold air to below the melting point, solidifying, and finally crushing with a crusher, and the concept of dust explosion accompanies the final crushing step. Therefore, solving the various problems related to the drying as described above is also an important step for realizing the purification by the water medium method. (Philosophy of the Invention) Thus, in order to industrially enable purification of crude SE with water and recovery of unreacted sugar, removal of the reaction solvent and the purified solvent is complete, and the sugar and product SE are lost. The major premise is to develop a purification method that does not cause However, in the purification of the reaction mixture based on this idea, it is inevitable that a large amount of unreacted sugar migrates to the water side, because the difference in solubility between SE and unreacted sucrose in water is basically used.
Without purification and recovery of this dissolved sugar, this industry cannot survive economically or socially. Therefore, how to effectively recover the sugar transferred to the aqueous phase side during purification is an important subject of the invention.

[Problems to be solved by the invention]

Therefore, the problem to be solved by the present invention is to industrially, without using a solvent for purification, a technique for obtaining purified SE and incidentally to efficiently remove unreacted sugar in a reaction mixture. It is to solve any problems caused by the use of the reaction solvent and the purified solvent by developing a means for recovering.

[Means for Solving the Problems]

[Contents] a: History of the invention b: Overview c: Framework of the invention d: Synthesis of SE by the solvent method e: Hydrolysis f: Salting out g: Reverse osmosis h: Washing i: Spray drying (a History of the invention) The inventor has (a) minimizing the amount of SE dissolved in the aqueous phase, (b) avoiding the decomposition of unreacted sugar, and (c) dissolving the residual reaction solvent outside the aqueous phase. , Separating from SE, (d) pulverizing the precipitated SE in a purified state, (e) Efficiently recovering unreacted sugar in the filtrate (or supernatant) separated from the precipitate on (e) As a result of conducting many salting-out experiments aiming to solve the above five points, when a neutral salt was dissolved in an aqueous solution of a reaction mixture, an appropriate pH, temperature, concentration of the neutral salt, and water amount were combined. Not only is SE precipitated in a large proportion below, but surprisingly, the reaction solvent is dissolved in the aqueous phase in addition to the unreacted sugar. We found a good phenomenon of the case. Therefore, by utilizing this phenomenon, the precipitated SE is redissolved in water again, and the precipitation operation with a neutral salt is repeated to suppress the loss of SE to a minimum, while remaining volatile components (remaining reaction solvent )
Of the unreacted sugar in the SE reaction mixture in a purified state can be efficiently performed by contacting the residual liquid from which the precipitate is removed with an appropriate reverse osmosis membrane. Can be recovered at the same time; and the SE precipitated above
It was revealed that the powdery SE can be continuously produced by spray-drying the slurry of 1. (B Outline) The present invention is based on the above discovery, and in addition to the target sucrose fatty acid ester, a reaction mixture containing unreacted sugar, unreacted fatty acid methyl ester, catalyst, soap, fatty acid and volatile matter is provided. Adjust the pH in the neutral range, wash the precipitate produced by adding water and neutral salt with acidic water,
A method for producing a powdered sucrose fatty acid ester is characterized in that the sucrose is recovered by contacting the water phase side from which the precipitate has been removed with a reverse osmosis membrane, and the precipitate is dissolved in water and spray-dried. . (C Skeleton of the Invention) Accordingly, the present invention comprises the following steps. (I) A step of removing impurities from the crude SE reaction mixture (salting out step). (II) A step of concentrating and recovering unreacted sucrose in the crude SE reaction mixture (reverse osmosis step). (III) Impurity SE purification step (pickling step). (IV) Powder Drying by Spray Drying Hereinafter, various matters related to the invention will be explained. (D Synthesis of SE by Solvent Method) In the synthesis of SE by the solvent method, usually, a mixture of sucrose with a fatty acid methyl ester is added to a reaction solvent in an amount several times the total amount of these, for example, dimethyl sulfoxide, The reaction rate of 90% or more (fatty acid methyl ester standard) can be easily obtained by dissolving and maintaining at 80-90 ° C for several hours in the vicinity of vacuum 20-30 Torr in the presence of an alkaline catalyst such as potassium carbonate (K ₂ CO ₃ ). ) Produces an SE reaction mixture. Next, an organic acid such as lactic acid or acetic acid or a mineral acid such as hydrochloric acid or sulfuric acid is added to the SE reaction mixture in an equivalent amount in order to eliminate the activity of the alkaline catalyst in the SE reaction mixture. By this neutralization, the catalyst is converted into a potassium salt such as potassium lactate. Finally, the reaction solvent, such as dimethyl sulfoxide, is distilled off under vacuum to give a composition having the following composition range (reaction mixture after neutralization and distillation). Sucrose fatty acid ester = 15-74% Unreacted sugar = 1.0-80% Unreacted fatty acid methyl ester = 0.5-10% Neutral salt derived from potassium carbonate = 0.05-7% Soap = 1.0-10% Fatty acid = 0.5-10 % Volatile matter (remaining reaction solvent) = 5.0 to 30% At this time, the ester distribution of SE is 10 to 75 monoesters.
% (90 to 25% for diester or higher). The fatty acid roots mainly contained in each of the fatty acid methyl ester, the soap and the fatty acid are saturated and have a common C ₁₆ -C ₂₂ carbon number. (E Water) Next, water is added to the above reaction mixture, and water: reaction mixture = 5: 1 to 40: 1 (weight ratio) (1). : Reaction mixture = 20: 1 (weight ratio) ... Add to the ratio of the formula (2), and adjust the pH to 6.2 to 8.2, preferably pH.
7.5. In this case, when the addition ratio of water is out of the above range, for example, when the amount ratio of water to the reaction mixture is less than 5,
The viscosity of the obtained aqueous solution becomes large, and subsequent operations become substantially difficult. Conversely, the ratio of water to the reaction mixture is
If an excess of water is added so as to exceed 40, the viscosity becomes small and the subsequent operation becomes easy, and the desired reaction solvent is preferably removed. When recovering water, a great deal of energy cost is required for removing water, and economic efficiency is lost. In addition, the aqueous solution should be
It is preferably adjusted to a pH between 6.2 and 8.2. At a hydrogen ion concentration of p8.2 or higher, there is a concern that quantitative decomposition of SE by alkali may occur, and even in a weakly acidic range of pH 6.2 or lower, when exposed to a high temperature of 90 ° C or higher, for example, acid decomposition of SE occurs. There is a fear. (F Salting-out) The aqueous solution of the SE reaction mixture, the pH of which has been adjusted as described above, is kept at 50 to 80 ° C as much as possible, and a neutral salt is further added. From the results of a number of experiments, the present inventors have shown that when an aqueous solution containing a precipitate of SE obtained by adding a neutral salt is heated to 50 to 80 ° C. and heated, the amount of SE eluted to the aqueous phase side is increased. It was found that even if the composition of the volatile matter (remaining reaction solvent) contained in this reaction mixture fluctuates significantly from 3.0 to 30.0%, most SE precipitates. . Such a phenomenon that SE is precipitated only by the addition of a neutral salt and the volatile component shifts to the aqueous phase side is a unique phenomenon, and the object of the invention is to remove the volatile component in the reaction mixture without using water. In addition, it has important significance. Now, the weight of SE dissolved in the water phase side = Y [g] The weight of precipitated SE = X [g] The total SE (X + Y) [g] is dissolved in the water phase side If SE weight ratio = φ [%], φ is defined by the following equation (3). Here, the following sample reaction mixture (dry matter) was dissolved in 20 volumes (weight ratio) of water and heated to 75 ° C at pH 7.8, and fatty acid residue = stearic acid SE composition (dry matter) in the sample Sugar fatty acid ester = 94% (ester distribution; monoester = 73%, diester or higher = 27%) Unreacted fatty acid methyl ester = 2% Soap = 2% Fatty acid = 1% Others = 1% Neutral to various concentrations When salt is added, when the added salt is sodium chloride, mirabilite, potassium lactate or potassium acetate,
The results shown in Table 1 below can be obtained. As is clear from the above table, the value of φ decreases as the amount of total salt increases, but it tends to decrease when it exceeds 3.5%, and it does not decrease even if it increases to 7.5% or more. It In addition, the above tendency shows that the amount ratio of the volatile matter (residual reaction solvent) contained in the initial reaction mixture is 3.0 to 30.0.
It was also confirmed that even if it changed significantly, it was hardly affected. That is, in such a SE-water-salt ternary system, the amount of volatile matter changes significantly, and even if the type of neutral salt added changes, the value of φ only depends on the concentration of the total salt. It is decided. Although the reason for this is not yet clear, it is certain that one of the causes is that the degree of formation of micellar aggregates of SE and the so-called salting out effect of salt are intricately intertwined. The degree of salting-out action above, in other words, the value of φ varies somewhat depending on the ester distribution of SE and the type of fatty acid residue in SE, but the total salt amount exceeds 6% (94% water). However, the tendency that the minimum of φ does not decrease is the same. Conversely, when the amount is less than 6% (water 94%), the value of φ increases, and the dissolution loss of SE increases, which is not desirable. Therefore, in order to reduce the value of φ, the dissolution loss of SE to the aqueous layer side can be minimized by keeping the amount of salt at 6% (water 94%) or more. (G Reverse Osmosis) << g-1 Outline >> Next, sucrose separated along with water from the SE synthesis reaction mixture by the salting out step and by-product salt from the catalyst (K ₂ CO ₃ ) and salting out Therefore, it is an important condition for achieving the object of the invention to selectively separate and recover only sucrose from the aqueous solution containing the added neutral salt and volatile matter. However, the inventors have found that the use of the reverse osmosis method is particularly effective for this purpose. If you select a reverse osmosis membrane with a molecular weight cut-off in the range of 150 to 200, unreacted sugar (molecular weight 342) or SE that accidentally washed away to the filtrate side due to salting out in the previous stage (molecular weight 600 or more)
Both are expected to be filtered out without problems. On the other hand, if the molecular weight cut-off of the membrane is less than 150-200, a by-product salt from the catalyst such as potassium lactate (molecular weight 128)
Alternatively, added neutral salts and volatiles, such as dimethyl sulfoxide (MW 78), will pass through the micropores of the reverse osmosis membrane without problems. As a result of many experiments based on this estimation, sucrose that had undergone the salting-out treatment in the previous stage, by-product salts from the catalyst, neutral salts and volatile components added during salting-out, and in some cases a small amount to a small amount of SE Aqueous solution containing, at a temperature of 40 ~ 60 ℃,
When brought into contact with a reverse osmosis membrane with a molecular weight cutoff of 150 to 200 while applying a higher pressure as a driving source than during ultrafiltration, by-product salts from the catalyst, added neutral salts and volatile components It was found that the three of them easily pass through the micropores of the reverse osmosis membrane together with water. By this reverse osmosis operation, an impure sucrose aqueous solution (which may contain a small amount of SE in some cases) is produced from water, by-products from the catalyst, neutral salts added during salting out, and low molecular weight substances such as volatile matter. It is in the form of a crude aqueous sugar solution which is separated and concentrated. Then, the crude sugar aqueous solution obtained here is dissolved again in fresh water and subjected to the same reverse osmosis treatment again (or again) to obtain a sucrose aqueous solution having a higher purity. In the above, the temperature of the aqueous solution to be supplied to the reverse osmosis membrane is important for expecting good results, and if the temperature is reduced to 40 ° C. or less, the processing capacity is significantly reduced. It is better to choose a temperature of 40 ° C or higher. However
If it exceeds 60 ° C, the heat resistance of the reverse osmosis membrane will be problematic, so it is advisable to treat at a temperature below the upper limit temperature.
In addition, the pH of the above-mentioned aqueous solution is also important in practice.
It is preferable that the area within 8.2 is less likely to affect the quality of sucrose. << g-2 Reverse Osmosis Membrane >> Many industrial reverse osmosis membranes that have advanced in recent years are put on the market. Among these commercially available membranes, a cross-linked polyamide reverse osmosis membrane is an example of one having excellent durability, heat resistance, acid resistance, alkali resistance, fungus resistance and pressure resistance.
And as an example of this type of membrane, for example, reverse osmosis membranes sold by Toray Engineering Co., Ltd., trade name << SU-200 >>
And the like have a value of the above-mentioned molecular weight cutoff of about 200, which is well suited to the object of the present invention. Generally, in the case of a reverse osmosis membrane having a molecular weight cutoff of about 200, the solute concentration in the supplied aqueous solution is 20% as the upper limit value, and preferably 15% as the upper limit value of the solute concentration, the industrial solute concentration is suppressed. It is possible to exert high processing capacity. If the solute concentration exceeds 20%, it becomes difficult for water, by-product salts and volatile components from the catalyst to pass through the micropores of the reverse osmosis membrane, and the driving pressure must be increased accordingly. As a result, the film area must be wide, and
It is very uneconomical because it requires a lot of power.
On the other hand, if the solute concentration is about 8 to 15%, industrial separation of sucrose is sufficiently possible. For example, Table 2 below
For aqueous compositions, the separation rate of sucrose, pH 7.5, temperature 50 ° C., when the driving pressure 56.0kg / cm ² G, the reverse osmosis membrane of one unit per effective area 8m ² "SU-200" so, And almost the same results were obtained with similar membranes of other companies. In all cases, dissolved SE could be recovered in good yield together with sucrose. In the above reverse osmosis treatment, about 15 to 20% of the sucrose-containing aqueous solution in which the by-product salt, the added neutral salt and the volatile matter from the catalyst are sufficiently removed by the repeated reverse osmosis membrane treatment is about 15 to 20%. The sugar concentration can be maintained. It is technically difficult to obtain a sugar aqueous solution having a concentration of 20% or more, and the economic efficiency is reduced. Therefore, if a sugar concentration other than the above is desired, it can be concentrated to a desired concentration, for example, 50% or more, using an ordinary concentrating device such as a multiple vacuum effect can. (H Washing) After the above salting-out operation, the above-mentioned separation was carried out using acidic water adjusted to pH 3.0 to 5.5 and temperature of 10 to 40 ° C.
Wash the SE cake. The acids used here include:
For example, mineral acids such as hydrochloric acid and sulfuric acid, and edible organic acids such as acetic acid and lactic acid are suitable, but not limited to those exemplified separately. By washing under such conditions, impurities can be transferred from the cake side to the aqueous phase side. Hereinafter, Table 3 below illustrates the amount of SE dissolved in the aqueous layer when the washing with acidic water is applied to SE (sucrose stearate) starting from stearic acid methyl ester. In the table, φ is defined by the above equation (3). In the above washing process, if the temperature of the acidic water is 40 ° C. or higher, not only is there a concern about acid decomposition of SE when the operation is for a long time, extremely long for several months, the viscosity increases. It becomes difficult to operate. On the other hand, maintaining a low temperature of 10 ° C or lower is not desirable from the economical point of view. Therefore, it is usually preferable to operate at 10 to 40 ° C, especially near room temperature. When washing the SE cake with this acidic water, unreacted sugar contained in the cake, added neutral salt, and salt by-produced by neutralization of the catalyst are removed from the SE cake as much as possible. Since it needs to be removed, it is desirable that the SE cake be subdivided in the acidic water to the smallest particle size possible. This purpose is, for example,
It can be efficiently achieved by a fragmentation device such as a dispersion mixer (for example, "Homomixer" manufactured by Tokushu Kikai Kogyo Co., Ltd.), a homogenizer or a colloid mill (for example, trade name "Mycoloider"), and unreacted sugar and catalyst-derived The salts and neutral salts migrate from the precipitated SE cake into the acidic aqueous phase. However,
At this time, some of the SE
It is unavoidable that it elutes in the acidic aqueous phase. Since the tendency of dissolution in acidic water is stronger for SE with a higher content of monoester,
It can be decreased by relatively increasing the diester or triester content. The above-mentioned washing of the SE cake with acidic water becomes more complete due to the increase in the number of washings and the amount of washing water, and thus, purified SE from which impurities such as neutral salts and unreacted sugars have been removed.
Can be obtained. (I Spray Drying) << Outline of i-1 >> As a result of research, the present inventor has found that the spray drying method is particularly suitable for drying the SE cake. This method is the best method for dewatering and drying SE mud having a solid content of 4 to 40%, which the present inventors have found from many experimental facts. Incidentally, as described above, also in the case of using a normal vacuum dryer represented by a so-called groove-type stirring dryer, the slurry is continuously supplied and heated to be discharged into the vacuum chamber. Even when using a so-called flash type dryer, it is not possible to avoid deterioration of quality such as increase in acid value of treated SE, coloring, caramelization, etc. due to viscosity characteristics and low melting point of SE. Moreover, in the latter case, the danger of dust explosion cannot be ignored. However, by adopting the spray drying means found by the inventor, the drawbacks of the past drying means can be solved all at once. In the drying step in the present invention, pH-adjusted water-containing SE in the form of an aqueous solution or sludge is continuously supplied to a spray-drying tower via a pump, sprayed by a nozzle or centrifuged on a rotating disk (disk). It is divided into fine mist-like fine particles by force and brought into contact with the dry air flow. As a result, the evaporation area of water is remarkably increased, so that dehydration and drying can be completed within a very short time (within a few seconds after spraying). As the atomization means, it is desirable to use a rotating disk because the viscosity of the water-containing SE is large. << i-2 Spray Drying Conditions >> The supply temperature of the SE solution or the slurry can be arbitrarily changed between 40 and 80 ° C, but from the viewpoint of quality, it is desirable to select a temperature within the range of 40 to 60 ° C. When the above solution or slurry is atomized by a rotating disk,
For example, when the diameter of the disk is 5 to 10 cmφ, 15,000 to 24,0
A rotation speed of 00 rpm is appropriate. The air blown into the tower should possess more heat than is necessary to evaporate the water in the solution or slurry, and therefore requires a larger amount of air when the air temperature is low. The air temperature at this time may be in a wide range of 10 to 100 ° C., but in consideration of the drying efficiency of the target SE and prevention of thermal decomposition,
It is advantageous to choose a temperature between 8080 ° C. The humidity in the blown air is related to the drying efficiency together with the air temperature. The absolute humidity suitable for work is roughly Is economical. If the solids concentration in the slurry sent to the spray drying tower exceeds 40%, the viscosity will increase significantly, and the particle size of the sprayed slurry will be relatively large, and the drying of water will be slowed accordingly. As a result, it easily adheres to the inner wall of the drying tower. Therefore, it is preferable to adjust the solid content concentration in the slurry to 40% or less. When the solid content concentration of the slurry is 40% or less, the diameter of the sprayed droplets is smaller than that when the diameter is more than 40%, and the particles are easily dried. If the solid content of the slurry is small, for example, less than 3%, drying becomes easy, but it is uneconomical in terms of required energy. Therefore, as the slurry supply concentration to the spray drying tower,
A range of 4% to 40% is suitable. Various conditions such as required volume, required tower diameter and required height of the spray drying tower are designed on the premise of the above spraying conditions. If the tower design and working conditions are appropriate, powdered dry SE with a water content of 5% or less is continuously discharged from the lower part of the spray drying tower. The obtained product has a short heat history, so that it is extremely excellent in quality and requires almost no personnel for the drying operation.

[Action]

Unreacted sugar, unreacted fatty acid methyl ester, catalyst,
SE containing soap, fatty acids and volatiles (remaining reaction solvent)
After adjusting the pH of the neutral region by adding an acid to the reaction mixture,
When water and neutral salt are added and salting out at an appropriate temperature, S
E, unreacted fatty acid methyl ester, soap and fatty acids are precipitated, and unreacted sugar migrates into the aqueous phase,
Volatile components (remaining reaction solvent) also move to the water phase side,
Residual volatiles and sugars can be removed without using any organic solvent. Thus, by subjecting the aqueous phase to reverse osmosis treatment, the unreacted sugar can be recovered as a high-purity sugar solution. Next, by washing the salting-out precipitate with acidic water to minimize the dissolution loss of SE, the volatile components contaminated during the precipitation, unreacted sugar, added neutral salt and catalyst Impurities such as salt produced as a by-product are removed from the mixture to obtain sugar SE slurry, which is spray-dried to achieve industrially high-quality powder SE.

【Example】

Hereinafter, embodiments of the invention will be specifically described with reference to examples, but each exemplification is naturally for explanation and has no direct relation to the technical scope of the invention. Example-1 Solvent-method SE reaction mixture having the composition shown in Table 4 below, the reaction solvent was distilled off, and the residual liquid was neutralized with lactic acid and dried.
2,000 kg of water was added to 100 kg to dissolve. The SE content in the filtrate filtered from the cake is
The loss of SE was 1.5% of the initial amount as measured by gel filtration chromatography (GPC) method (see above, page 63). Example-2 Then, the salting-out filtrate (2,230 kg; an aqueous solution containing the remaining sucrose, which precipitated SE by salting-out, salts and volatile matter; pH
7.7) is heated to 55 ℃, pump pressure 60Kgcm ² G, two cylindrical reverse osmosis units (each 4 ″ φ) equipped with a reverse osmosis membrane (<< trade name << SU-200 >>; molecular weight cut off about 200) × 1 meter,
A filtration area of 8 m ² ) was supplied under the following conditions. Discharge rate of the aqueous solution that permeates the membrane = 4.8-9.2 / min Circulation rate around the reverse osmosis membrane = 18-20 / min Feeding time = about 6 hours The composition of the concentrated sugar and salt-enriched liquid without permeating the membrane Shown as Table 6 below. Then, 2,000 kg of water was added to the aqueous solution shown in Table 6 and treated with a reverse osmosis membrane under substantially the same conditions to obtain an aqueous solution having the composition shown in Table 7 below. 2,000 kg of water was further added to the aqueous solution shown in Table 7 above and treated with a reverse osmosis membrane under the same conditions as above, resulting in an aqueous solution having the composition shown in Table 8 below. Example-3 Potassium lactic acid salting-out cake of Example-1 (water content 48.1%; composition of solids thereof is described in Table 5 above) 2,000 kg of water was added to 122.5 kg, the pH was adjusted to 3.5, and a homogenizer was used. After stirring uniformly, the precipitate was filtered off, and the weight of the precipitate cake after adjusting to pH = 7.3 was 129.0 Kg, and the composition thereof is as shown in Table-9. (In dry state) Example-4 Finally, this slurry (temperature: 50 ° C.) was spray-dried under the following conditions. Spray drying tower diameter: 2.0mφ Length of straight tube: 1.5m Rotating disk (disk) diameter: 10 cm φ Disk rotation speed: 24,000 rpm Inlet air temperature: 65 ° C The powdery SE obtained from the lower part of the spray drying tower had a moisture content of 2.01
%, Bulk specific gravity 0.43, no coloring due to overheating, and good fluidity. The amount of monoester in the powdered SE obtained here is 49.3%.
It was the same as before drying and the acid value was also unchanged. Incidentally, the drying could be stably continued, and troubles such as adhesion to the inner wall of the spray-drying tower which was originally conceived did not occur.

【The invention's effect】

As described above, the present invention enables the production of industrially purified powdery SE from a reaction mixture using a solvent method without using a solvent for purification, and recovers unreacted sugar in the reaction mixture. By providing the means, the following great effects are achieved. (1) SE can be purified using only inexpensive water. (2) SE can be dried under normal pressure within a short period of time, so there is no heat deterioration of the product. (3) There is no fear of explosion or fire of the solvent, so that expensive electric equipment of explosion-proof specification is not required. (4) There is no concept that the purification solvent is mixed in the product. (5) Improve the workplace hygiene environment. (6) It can be industrialized at low cost.

Claims (20)

(57) [Claims] 1. An unreacted sugar unreacted fatty acid methyl ester, a catalyst, a soap, in addition to a sucrose fatty acid ester as a target substance.
The reaction mixture containing fatty acid and volatile matter is adjusted to a pH in the neutral range, and the precipitate produced by adding water and a neutral salt is washed with acidic water, and the washed precipitate is neutralized and then spray-dried. A method for producing powdery sucrose fatty acid ester, which comprises recovering sucrose by bringing the aqueous phase side from which the precipitate has been removed into contact with a reverse osmosis membrane. 2. The process according to claim 1, wherein the reaction mixture is adjusted to a pH of 6.2 to 8.2 with an acid. 3. The method according to claim 1, wherein the pH-adjusted reaction mixture is heated to 50 to 80 ° C. 4. The weight ratio of water and reaction mixture added to the reaction mixture is water: reaction mixture = 5: 1 to 40: 1.
The described method. 5. The acid used for adjusting the pH of the reaction mixture,
The method according to claim 1 or 2, wherein the method is any one of acids selected from the group consisting of lactic acid, acetic acid, hydrochloric acid, and sulfuric acid. 6. The composition of the reaction mixture is as follows: sucrose fatty acid ester = 15.0 to 92.0% unreacted sucrose = 1.0 to 80.0% unreacted fatty acid methyl ester = 0.5 to 10.0% catalyst = 0.05 to 7.0% soap = 1.0 The method according to claim 1, wherein -10.0% fatty acid = 0.5-10.0% volatile matter = 3.0-30.0%. 7. The fatty acid radical mainly contained in each of the fatty acid methyl ester, soap and fatty acid in the reaction mixture has a common saturated fatty acid radical having 16 to 22 carbon atoms.
The described method. 8. The method according to claim 1, wherein the volatile component (remaining reaction solvent) in the reaction mixture is dimethylsulfoxide or dimethylformamide. 9. The neutral salt added to the reaction mixture is sodium chloride,
A salt selected from the group consisting of Glauber's salt, potassium lactate and potassium acetate, wherein water / neutral salt <94/6
The method according to claim 1, which is (weight ratio). 10. The method according to claim 1, wherein the ester distribution of the sucrose fatty acid ester is 10 to 75% (90 to 25% for diesters or more) as monoester content. 11. The method according to claim 1, wherein the pH value of the acidic water is 3.0 to 5.5. 12. The method according to claim 1, wherein the temperature of the acidic water is 10 to 40 ° C. 13. The method according to claim 1, wherein the reverse osmosis membrane has a molecular weight cutoff of 150 to 200. 14. The method according to claim 1, wherein the reverse osmosis is performed within a temperature range of 40 to 60 ° C. 15. The method according to claim 1 or 15, wherein the reverse osmosis is carried out within a pH range of pH 6.2 to 8.2. 16. The method according to claim 1 or 14, wherein the reverse osmosis membrane is made of crosslinked polyamide plastics. 17. The sucrose concentration in the solution supplied to the reverse osmosis membrane is 10.
The method according to claim 1, which is -20%. 18. Slurry of sediment to be spray dried.
The method according to claim 1, wherein the solid content is 4 to 40% and the water content is 96 to 60%. 19. The humidity and temperature of the blast air during spray drying are The method according to claim 1, wherein the temperature is in the range of 10.0 to 10.00.0C. 20. The method according to claim 1, wherein the composition of the powdery sucrose fatty acid ester of the product is within the following range. Water content = 0.5-5.0% Unreacted fatty acid methyl ester = 0.5-10.0% Soap = 0.5-60.0% Fatty acid = 0.5-10.0% Sucrose fatty acid ester = 98.5-15.0%