JP2001157568A - Food additive lactide - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a food additive lactide. SOLUTION: A high-purity refined lactide is obtained by contacting a crude lactide in a solid state of a partly or wholly molten state with ethanol to obtain a mixture in a slurry condition followed by separating the solid from the mixture. The food additive lactide is obtained by recrystallizing a crude lactide from a native ethanol or denatured ethanol. A food preservative is provided by using the above lactide as the main component.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a food additive using lactide, which is a dimeric cyclic ester of lactic acid.

[0002]

2. Description of the Related Art Lactide has conventionally been useful as a raw material for producing polylactic acid, which is a biodegradable polymer.
That is, polylactic acid is obtained by ring-opening polymerization of lactide. In addition to such polylactic acid production raw materials, lactide will be used as a food storage stabilizer, pH adjuster, coagulant,
It is expected to be used as food additives such as acidulants and expansion aids.

[0003] Lactide is a dimeric cyclic ester of lactic acid, and has three kinds of optical isomers, namely, L-lactide composed of two molecules of L-lactic acid, D-lactide composed of two molecules of D-lactic acid, and L-lactic acid. And D-lactic acid.

[0004] Usually, lactide is obtained by dehydrating and condensing lactic acid to obtain relatively low molecular weight polylactic acid as an intermediate, and then depolymerizing and cyclizing the polylactic acid to produce lactide, which is reacted as steam. It is manufactured by a so-called reactive distillation method that is taken out of the system.

In such a production method, lactide vapor contains L-lactide and / or D lactide and meso-lactide.
As impurities other than lactide, lactic acid monomers, linear lactic acid dimers, low molecular weight lactic acid condensation polymers such as trimers,
And water. Furthermore, impurities such as saccharides, amino acids, and fatty acids other than lactic acid derived from the raw material lactic acid may be included. Therefore, it is necessary to purify the crude lactide collected by cooling according to the purpose of use to reduce the content of these impurities and meso-lactide.

That is, lactide is converted to lactic acid and linear low molecular weight lactic acid polycondensate by hydrolysis, while meso-lactide has remarkably higher water absorption and hydrolyzability than L-lactide and D-lactide. Therefore, lactide having a high content of meso-lactide is rapidly hydrolyzed as a whole, and has a high content of lactic acid as an acidic component and a linear low molecular weight lactic acid polycondensate.

For example, when lactide is used as a food additive, it is more useful to use lactide, which has a low acidity at the initial stage of addition and increases the acidity over time (according to aging of the food). If meso-lactide, lactic acid, or a linear low molecular weight lactic acid polycondensate is contained in a large amount in lactide, the acidity in the initial stage of the addition is increased. Therefore, it is preferable that the contents of meso-lactide, lactic acid, linear low molecular weight lactic acid polycondensate and water in lactide are as small as possible.

The melting points of L-lactide and D-lactide are about 98 ° C., whereas those of meso-lactide are about 40 ° C. The melting point of lactic acid is 16 to 25 ° C., and the linear low molecular weight lactic acid polycondensate is liquid at room temperature. For this reason, when lactide is used in the form of powder or particles, the melting point is lower than or equal to room temperature or near room temperature, meso-lactide, lactic acid, linear low molecular weight lactic acid polycondensate, and the water content is high. Thus, there is a problem that the flowability of lactide deteriorates and the workability is impaired. Therefore, the content of these in lactide is preferably as small as possible.

Further, when lactide is used as a food additive, impurities such as saccharides, amino acids, and fatty acids other than lactic acid contained in lactide may make the taste of the food additive worse or change. There is a problem of coloring food additives. Therefore, the content of these impurities in lactide is preferably as small as possible.

Various conventional lactide purification methods are known, such as a method by recrystallization, a method by melt crystallization, a method by rectification, and a method by extraction with water.
For example, Japanese Patent Publication No. 51-6673 discloses a method of recrystallizing lactide using amyl alcohol or butyl alcohol as a solvent. But in this case,
Organic solvents harmful to the human body remain in the purified lactide, which is problematic when used as a food additive.

JP-A-63-101378 discloses that lactide is recrystallized from an alcohol having 1 to 6 carbon atoms, preferably isopropyl alcohol, or that lactide is dissolved and then precipitated using a non-solvent. ing. Japanese Patent Application Laid-Open No. Hei 7-118259 discloses a method in which lactide is recrystallized from a lower alcohol and then recrystallized with benzene or the like. However, in these cases, in the step of heating and dissolving the crude lactide in a solvent or in the step of cooling and depositing lactide from a solution, a large amount of time and utility is required, and a large amount of solvent is required. In addition, since the yield is low, it is disadvantageous in terms of cost. Further, an organic solvent harmful to the human body remains in the purified lactide, which is problematic when used as a food additive.

JP-A-6-256340 discloses a method for purifying crude lactide by a melt crystallization method.
However, the melt crystallization method requires an expensive large-scale apparatus, and requires a large amount of time and utility in the step of cooling and depositing lactide or the step of heating and purifying / dissolving lactide. Disadvantageous. In addition, since purified lactide is separated at a high temperature equal to or higher than the melting point of lactide, lactide is newly decomposed during the purification step, that is, lactic acid, linear low-molecular-weight lactic acid polycondensate, and the like are generated. . In order to obtain lactide of stable quality, strict process control is required.

JP-A-7-505150 discloses a method for obtaining high-purity lactide by rectification.
However, the equipment required for rectification is complicated and expensive, and requires a large amount of utility in the step of heating and vaporizing lactide or in the step of cooling and condensing it.
It is disadvantageous in terms of cost. Further, since purified lactide is separated at a high temperature equal to or higher than the melting point of lactide, lactide is newly decomposed during the purification process, and lactic acid, linear low-molecular-weight lactic acid polycondensate, and the like are generated. In order to obtain lactide of stable quality, strict process control is still required.

Japanese Patent Application Laid-Open (JP-A) No. 7-165753 discloses a method of purifying crude lactide by bringing it into contact with water. In this method, lactide is brought into contact with water to remove meso-lactide.
If an attempt is made to sufficiently remove lactide, L-lactide and / or D-lactide are also partially hydrolyzed and removed, resulting in a low yield. The removed L-lactide and / or D-lactide reacts with water and can be recovered only in the form of lactic acid or a linear low-molecular-weight lactic acid polycondensate. Lactide obtained from lactic acid using a lot of utilities,
It is very disadvantageous in terms of cost that it can be recovered only in the form of lactic acid or linear low molecular weight lactic acid polycondensate.

[0015]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to solve the above-mentioned problems of the prior art and to obtain a highly purified lactide with high yield and high purity by using simple equipment and simple steps. To provide a purification method of Further, an object of the present invention is to provide a method for purifying lactide, which is suitable for food additives without leaving an organic solvent harmful to the human body and obtains a purified lactide having particles having good fluidity. It is in. And the object of the present invention is
An object of the present invention is to provide a purified lactide suitable for use as an inexpensive high-purity food additive. It is a further object of the present invention to provide a food additive based on lactide.

[0016]

Means for Solving the Problems As a result of intensive studies, the present inventors have found that L-lactide and / or D-lactide can be obtained by bringing crude lactide into contact with ethanol and then separating solids.
-It has been found that purified lactide having a high lactide content can be obtained in high yield, and the present invention has been completed. That is, the present invention relates to a method wherein L-lactide and / or D-lactide is obtained by contacting crude lactide in a solid state or at least partly in a molten state with ethanol to obtain a slurry-like mixture, and thereafter separating a solid content from the mixture. A method for purifying lactide, comprising obtaining a purified lactide having a high lactide content.

In the ethanol contact method, it is preferable that after the solid content is separated, the separated solid content is dried under reduced pressure. Further, in this method, after the solid content is separated, the separated solid content can be washed with water in order to remove ethanol. In this case, it is preferable to dry the solid content under reduced pressure after washing with water. In this ethanol contact method, both undenatured ethanol and denatured ethanol can be used as ethanol. Further, the present invention is a purified lactide obtained by the above-mentioned ethanol contact method.

The present inventors have conducted intensive studies and found that lactide for food additives can be obtained by recrystallizing crude lactide using unmodified ethanol or denatured ethanol as a solvent, thereby completing the present invention. Reached.
That is, the present invention includes recrystallizing crude lactide from undenatured ethanol to obtain lactide for food additives,
This is a method for purifying lactide. The present invention is also a method for purifying lactide, comprising recrystallizing crude lactide from denatured ethanol to obtain lactide for food additives.

The denaturing agent contained in the denatured ethanol is preferably selected from fragrances usable as food additives. When the denaturing agent contained in denatured ethanol is a synthetic chemical substance, ethyl acetate, butyl parahydroxybenzoate, white lac, purified shellac, white lac dissolution solution,
It is preferably at least one of the purified shellac solution.

Furthermore, the present invention is a lactide for food additives recrystallized from undenatured ethanol. The present invention is also a lactide for food additives recrystallized from denatured ethanol.

The present invention also relates to a novel use of lactide as a food additive such as an animal and / or vegetable protein coagulant, a food foaming agent, a food preservative, a pH adjuster, and an acidulant. Also concerns. That is, the present invention relates to a protein coagulant containing lactide having optical activity as a main component. The present invention also relates to a food foaming agent containing lactide as a main component. The present invention also relates to a food preservative containing lactide as a main component. Furthermore, the present invention relates to a pH adjuster containing lactide as a main component. Lactide used in these applications may be obtained by the above-described purification method of the present invention or may be obtained by other methods.

According to the present invention, purified lactide having a high content of L-lactide and / or D-lactide can be obtained in a short time and in a high yield by a simple apparatus and operation. Further, according to the present invention, a purified lactide having good workability can be obtained without leaving an organic solvent harmful to the human body. The purified lactide obtained according to the present invention is inexpensive and suitable for use in food additives.

[0023]

BEST MODE FOR CARRYING OUT THE INVENTION The purification method of the present invention can be applied to crude lactide obtained by a conventionally known method. For example, as described in JP-A-7-138253, a method of obtaining low molecular weight polylactic acid and depolymerizing the polylactic acid in the presence of a catalyst to obtain lactide,
No. 091, a thin film depolymerization method of a lactic acid oligomer, or JP-A-6-504762, U.S. Pat. Nos. 5,74,127, 5,332,839, and 5,31.
As described in 9,107, 5,420,304,
Any method such as a method for producing lactide directly from lactic acid without passing through a lactic acid oligomer may be used. Of course, it is not limited to lactide by these methods.

As the raw material lactic acid for the production of lactide, for example, those having a lactic acid monomer equivalent weight concentration of 50 to 95% obtained by a synthesis method or a fermentation method can be used. Lactic acid obtained by the synthesis method contains an equal amount of an L-lactic acid component and a D-lactic acid component. Lactic acid obtained by the fermentation method is a mixture of an L-lactic acid component and a D-lactic acid component, and there are those mainly containing an L-lactic acid component and those mainly containing a D-lactic acid component. When obtaining a purified lactide for use as a food additive, it is more preferable to use lactic acid obtained by a fermentation method than lactic acid obtained by a synthesis method using a harmful substance such as hydrocyanic acid or acetaldehyde in the production process.

In order to obtain a low molecular weight polylactic acid by polycondensation of lactic acid, the raw material lactic acid is usually dehydrated under heating and reduced pressure in the absence or presence of a catalyst to obtain a weight average molecular weight of 500 to 30,
000 polylactic acid. The heating temperature in this case is 10
The temperature is 0 to 250 ° C, preferably 100 to 200 ° C. 1
If the temperature is lower than 00 ° C., the condensation polymerization takes too long,
If it is higher, lactic acid and linear low molecular weight lactic acid polycondensate are distilled off simultaneously with water, and the yield becomes poor, which is not preferable. When lactic acid obtained by a fermentation method is used to obtain crude lactide having a high optical purity, the optical purity of the crude lactide obtained decreases as the reaction temperature increases, so that the racemization reaction is suppressed. ° C, preferably 100-1
Perform at a temperature of 80 ° C. The pressure is 100 Torr or less, preferably 50 Torr or less.

The catalyst used in this case is not particularly limited, but is usually a group IA, a group IIA or a group IIB of the periodic table.
Group III, group IVB, group IVA, group IVB, group VB metals,
Oxides, hydroxides, chlorides, other inorganic compounds, organic compounds and the like and acids are used alone or in combination. The amount of the catalyst is usually 5% by weight or less based on the raw lactic acid.

The group IA catalyst includes sodium hydroxide, potassium hydroxide, lithium hydroxide, sodium oxide, potassium oxide, lithium oxide, sodium methoxide, potassium ethoxide and the like. Group IIA catalysts include magnesium hydroxide, calcium hydroxide, barium hydroxide, magnesium oxide, calcium oxide, barium oxide, magnesium chloride, barium chloride and the like. Group IIB catalysts include zinc hydroxide, zinc oxide, zinc chloride and the like. Examples of the group IIIB catalyst include aluminum oxide, aluminum chloride, aluminum triethoxide, and aluminum octylate. Group IVA catalysts include titanium oxide, tetramethyl titanate, tetrabutyl titanate, zirconium, zirconium oxide, zirconium tetramethoxide, zirconium tetrabutoxide and the like. IV
Group B catalysts include germanium, germanium oxide, tin, tin oxide, tin chloride, tin oxalate, tin octylate,
Examples include dibutyltin dilaurate, dibutyltin oxide, butyltin chlorooxide, lead oxide, and silicon oxide.
Examples of the VB group catalyst include antimony trioxide, antimony triacetate, and triphenylantimony. Examples of the acid catalyst include sulfuric acid, hydrochloric acid, nitric acid, phosphoric acid, toluenesulfonic acid, and a cation exchange resin.

By using the above-mentioned catalyst, it is possible to accelerate the rate of the polycondensation reaction and shorten the time required for the reaction. However, since the use of these catalysts also promotes the racemization reaction of lactic acid, when using lactic acid obtained by a fermentation method to obtain lactide with high optical purity, no catalyst is used, or the catalyst is not used. It is preferable to reduce the amount used.

The obtained low-molecular-weight polylactic acid is depolymerized by heating under reduced pressure in the presence of a catalyst to produce lactide, which is taken out of the reaction system as a vapor to produce crude lactide. The heating temperature in this case is 130 to
The temperature is 300 ° C, preferably 160 to 250 ° C. 130
When the temperature is lower than ℃, it takes too much time for the depolymerization. Further, when obtaining a crude lactide of high optical purity using lactic acid obtained by the fermentation method, in order to suppress the racemization reaction, 130 ~ 260 ℃,
Preferably from 130 to 220 ° C, more preferably from 130 to 220 ° C.
It is preferably performed at a temperature of 180 ° C. The pressure is 1
00 Torr or less, preferably 50 Torr or less, more preferably 20 Torr or less.

The depolymerization catalyst is not limited, but is usually selected from groups IA, IIA, IIB, IIIB and IVA of the periodic table.
Group, IVB and VB metals, oxides, hydroxides,
Chlorides, other inorganic compounds, organic compounds, etc. and acids,
Used alone or in combination. Specific examples of each of these catalysts are the same as those described above.

The catalyst is preferably used in an amount of not more than 20% by weight based on polylactic acid. However, when a catalyst is used in the polycondensation step of low-molecular-weight polylactic acid and the catalyst remaining in the polylactic acid provides a sufficient depolymerization reaction rate, it is not necessary to add a new catalyst. Absent.

The crude lactide thus obtained includes:
Usually, low-molecular-weight lactic acid polycondensates such as lactic acid monomers, linear lactic acid dimers and trimers, and impurities such as water, and impurities such as saccharides, amino acids, and fatty acids other than lactic acid derived from raw lactic acid are contained. ing. Lactide also has L-
Lactide and / or D-lactide, and meso-lactide are included.

(Lactide purification by ethanol contact method)
In the ethanol contact method of the present invention, a crude lactide to be purified is brought into contact with ethanol to obtain a slurry-like mixture, and thereafter, a solid content is separated from the mixture.

The crude lactide to be purified may be in a solid state or a molten state. Alternatively, a part may be in a molten state. That is, it is possible to purify the crude lactide once solidified, or to purify the crude lactide obtained by depolymerizing low molecular weight polylactic acid while maintaining the molten state without solidifying it. it can.

Regardless of the state of the crude lactide, when the crude lactide is brought into contact with ethanol, a slurry-like mixture is obtained. The contact between the crude lactide and ethanol can be carried out batchwise or continuously.

The solid content is separated and recovered from the obtained slurry-like mixture. This operation can also be performed in a batch system or a continuous system. Further, the operation of contacting the crude lactide with ethanol and the operation of separating and collecting the solid content can be repeated a plurality of times. That is, after the crude lactide is brought into contact with ethanol, the solid content is separated, the obtained solid content is brought into contact with fresh ethanol again, and then the solid content is separated and recovered, and a repeated operation can be performed.

The ethanol used in the ethanol contact method of the present invention is a liquid mainly containing ethanol, and includes both undenatured ethanol and denatured ethanol. The content of ethanol is 50% by weight or more, preferably 90% by weight or more, and more preferably 95% by weight or more.

The denatured ethanol is obtained by mixing a denaturant with ethanol. As a modifying agent to be mixed,
Synthetic chemicals and natural substances are included. These denaturants can usually be used in an amount of 1 g to 200 g per liter of ethanol.

As synthetic chemicals, methanol, benzol, toluene, methyl ethyl ketone, denatonium benzoate, ethylene glycol monoethyl ether,
Chloroform, diethyl carbonate, ethyl acetate, ethyl propionate, ethyl butyrate, hexane, industrial ethyl ether, geraniol, octaacetylated sucrose, phenylethyl alcohol, diethyl phthalate, alkylbenzene sulfonate aqueous solution, vinyl acetate monomer, heptane, Isopropyl alcohol, butanol, ethyl acrylate, brucine, linalool, linalool acetate, benzyl acetate, seed vinegar, brewed vinegar, formalin, rhodamine B, white lac, purified shellac, white lac solution, purified shellac solution, paraoxybenzoic acid Butyl and the like can be used. Among them, ethyl acetate, butyl paraoxybenzoate, white lac, purified shellac, white lac dissolution solution,
Purified shellac solution is preferred as the denaturant.

As natural substances, distilled vinegar, orange recovery fragrance, grape recovery fragrance, wine recovery fragrance,
As a food additive such as natural butter flavor, fermented lactic acid, fermented grain extract, orange oil, lemon oil, lime oil, turmeric orange, vanilla extract, coffee recovery aroma, miso recovery aroma, soy sauce oil essence, malt essence, chicory essence Useable ones are listed. These may be used alone, but are usually used as a mixture.

In the case of obtaining purified lactide for use as a food additive, among these modifiers, fragrances derived from natural substances usable as food additives are particularly preferred. More specifically, flavors H-1 and H- manufactured by Hasegawa Koran Co., Ltd.
2, H-3, H-4, H-6, H-9, H-10, H-
11, H-12, H-13, H-14, flavors T-100, T-101, T-1 manufactured by Takasago International Corporation
02, T-103, T-104, T-105, T-10
6, T-107, EDA-171, flavor S-201 manufactured by Soda Perfume Co., Ltd., and flavor DA-40 manufactured by Riken Perfumery Co., Ltd. can be used. What kind of denaturing agent is used is variously selected depending on the use of the food additive.

In addition to the denaturing agent, ethanol mixed with water can be used. The amount of water mixed is 0 to 10 parts by weight, preferably 0 to 5 parts by weight, more preferably 100 parts by weight of ethanol. Is from 0 to 0.1 parts by weight. If the amount exceeds 10 parts by weight, the yield of purified lactide decreases, which is not preferable.

When obtaining purified lactide for use as a food additive, it is of course preferable to use undenatured ethanol. Undenatured ethanol is ethanol in which a denaturant is not mixed.

Upon contact with the crude lactide, ethanol can be used in an amount of usually 10 to 600 parts by weight, preferably 20 to 400 parts by weight, more preferably 30 to 200 parts by weight, based on 100 parts by weight of the crude lactide. If the amount of ethanol is less than 10 parts by weight, separation of meso-lactide and various impurities tends to be insufficient. On the other hand, when the amount exceeds 600 parts by weight, the separation of impurities is sufficient, but the yield of purified lactide decreases, and the cost is disadvantageous because of the large amount of ethanol used.

When the crude lactide in the solid state is brought into contact with ethanol, the coarse lactide particles preferably pass through 4 mesh, preferably through 6 mesh, more preferably through 10 mesh. In the case of coarse lactide particles that do not pass through the 4 mesh, a sufficient contact area between the crude lactide and ethanol cannot be obtained, so that the separation of impurities tends to be insufficient.

Crude lactide previously crushed into particles that have passed through 4 mesh may be used, or the crude lactide may be crushed to 4 mesh or less by a stirrer or the like while contacting with ethanol.

As a method for previously grinding the crude lactide,
Although not particularly limited, for example, pulverization can be performed using a coarse crusher such as a jaw crusher mill, a hammer crusher mill, a roll crusher mill, a cage mill, a hammer mill, or a medium crusher. If necessary, a particle classifier or the like may be used after the pulverization to remove particles that do not pass through the 4-mesh.

The method for bringing the crude lactide in solid state into contact with ethanol is not particularly limited,
A method in which crude lactide and ethanol are put in a container and left to contact them, a method in which the crude lactide is contacted in a container equipped with a stirrer, a method in which the crude lactide is contacted in a solid-liquid extraction device, and the like are used.
In addition, using a plurality of these devices, the crude lactide can be brought into contact with ethanol in multiple stages.

On the other hand, the method of bringing the crude lactide in a liquid state into contact with ethanol is not particularly limited, but a method in which lactide particles precipitated by contact with ethanol are brought into contact with stirring in order to make the particles uniform. A method of discharging the crude lactide in a liquid state into ethanol through a nozzle or the like in the form of a shower or a spray is effective.
Further, the slurry obtained by contacting in a vessel equipped with a stirrer to precipitate lactide can be further contacted with fresh ethanol in a solid-liquid extractor.

Examples of the stirring device include a double ribbon blade stirring device, a full zone blade stirring device, a disk turbine blade stirring device, a rotating blade stirring device such as a homomixer, a stirring device using a jet stream and a circulating flow, and a stirring device using a static mixer. Is used. When the crude lactide is pulverized by a stirring device after or simultaneously with the mixing of the crude lactide and ethanol, among these stirring devices, a disk turbine blade stirring device having a large shearing effect, a homomixer, and the like are effective.

The solid-liquid extraction device includes a rotocell extractor,
A Kennedy extractor, a Bonoteau extractor and the like are used. In these solid-liquid extraction devices, ethanol can be brought into contact with the crude lactide, and the solid content can be separated in the same device. However, since the content of ethanol in the separated solid content is large, it is preferable to further perform an operation of re-separating the solid content using another device.

In the present invention, the temperature at which the crude lactide is brought into contact with ethanol is preferably a low temperature in order to suppress the decomposition of L-lactide and / or D-lactide by reaction with ethanol or water. ℃,
Preferably 10 to 50 ° C, more preferably 20 to 40 ° C.
It is about ° C.

When the molten crude lactide is brought into contact with ethanol, or when the temperature rises due to liquid friction due to stirring or the like, it is preferable to contact the crude lactide with ethanol while cooling to prevent the contact temperature from rising. .

The time for bringing the crude lactide into contact with ethanol should be determined according to the capacity of the apparatus and the purity of the purified lactide to be obtained.
0 hours.

In the present invention, a solid content is separated from a slurry mixture obtained by contacting crude lactide with ethanol. In addition, lactide can also be recovered from the ethanol solution after the solid content is separated by crystallization, concentration, or the like. This is one of the great advantages of the present invention, which cannot be realized by the purification method by contact with water described in JP-A-7-165755.

The method for separating solids is not particularly limited, but a method of separating using a centrifugal sedimentation machine, a centrifugal filtration machine, a pressure filtration device, or the like is used. When using a device having a function of rinsing solids among these devices, the operation of bringing the solids into contact with ethanol and the operation of separating the solids can be performed in parallel using the same device. Is effective in

As the centrifugal sedimentation machine, a vertical basket type centrifugal sedimentation machine, a screw decanter type centrifugal sedimentation machine or the like is used. As the centrifugal filter, a vertical basket type centrifugal filter, a screw decanter type centrifugal filter, a conical screen type centrifugal filter, or the like is used. As a pressure filtration device,
A gravity filter, a pressure filter, a vacuum filter, or the like is used.

By the above operation, a purified lactide solid content from which meso-lactide and other impurities have been removed can be obtained.

In the present invention, after the solid content is separated as described above, it is preferable to wash the separated solid content with water in order to remove ethanol from the solid content.
By washing with water, the content of ethanol in purified lactide can be significantly reduced, and problems such as residual ethanol odor of purified lactide are eliminated.

This water washing may be performed by bringing the solid content into contact with water. The water washing operation can be performed in a batch system or a continuous system. Further, the water washing operation can be repeated a plurality of times. That is, it is also possible to repeat the operation of contacting the solid content with water to separate the solid content, bringing the obtained solid content into contact with fresh water again, and then separating and collecting the solid content.

In this washing operation, water is usually added to 100 parts by weight of a solid content separated after contact with ethanol, and is usually 1 to 10 parts by weight.
0 to 200 parts by weight, preferably 20 to 100 parts by weight, more preferably 30 to 60 parts by weight can be used. If the amount of washing water is less than 10 parts by weight, the action of removing ethanol is somewhat weak. If it exceeds 200 parts by weight, the yield of purified lactide will be low.

The temperature of the water contact washing is preferably low to suppress the decomposition reaction of L-lactide and / or D-lactide, and is usually 0 to 40 ° C., preferably 10 to 3 ° C.
0 ° C, more preferably 10 to 20 ° C.

The washing time with water is preferably short in order to suppress the decomposition reaction of L-lactide and / or D-lactide, and the time required for ethanol to dissolve in water is sufficient. Therefore, it is usually 10 seconds to 20 minutes, preferably 10 seconds to 5 minutes, more preferably 10 seconds to 1 minute.

For the water contact cleaning, an apparatus similar to the above-described apparatus for bringing crude lactide into contact with ethanol can be used. Separation of the solid content from the slurry after contact with water can be performed using the same device as the solid content separation device described above. Among these devices, a centrifugal filter and a pressure filtration device having a function of rinsing solids are particularly preferable because the contact time with water can be shortened and uniform contact with water is possible. It is.

In the present invention, the solid separated after contact with ethanol as described above or the solid obtained after washing with water is preferably dried under reduced pressure. The purified lactide obtained as a solid content usually contains the used ethanol, water, and in some cases substances contained in ethanol (eg, water, methanol, isopropyl alcohol, methyl ethyl ketone, ethyl acetate, etc.).
Is attached. These adhesions may deteriorate the fluidity of the obtained purified lactide particles or may cause a problem of the odor. Therefore, in order to reduce the attached substance, the solid content may be dried under reduced pressure.

The drying under reduced pressure is preferably performed at a low temperature in order to suppress the decomposition of lactide by reaction with ethanol or water due to heating, and is usually performed at a low temperature of 10 to 95.
° C, preferably about 10 to 60 ° C, 0.01 to 1
It can be performed at a pressure of about 00 Torr. Also,
Freeze-drying can also be performed at a pressure of about 0.001 to 10 Torr and a temperature of 0 ° C. or less. The drying time should be determined depending on the capacity of the drying apparatus, the amount of lactide to be dried, or the content of ethanol and water in the purified lactide to be obtained, but is usually 5 minutes to 10 hours.

When the drying under heating and reduced pressure is carried out, a tray drying machine, a cylindrical stirring dryer, a conical rotary dryer and the like can be used without limitation. When freeze-drying is performed, a shelf-stage dryer can be used without limitation.

(Purification of lactide by ethanol recrystallization method) In the ethanol recrystallization method of the present invention, first, crude lactide is dissolved in ethanol. Next, a lactide crystal is preferentially precipitated from the lactide solution to obtain a slurry-like mixture, and thereafter, a solid content is separated from the mixture. Usually, the separated solid is dried to obtain a purified lactide.

A series of operations from dissolving the crude lactide in ethanol to separating the precipitated solid can be repeated a plurality of times. Usually, the separated solid is dried to obtain a purified lactide.

Ethanol used in the ethanol recrystallization method of the present invention can be used in the same manner as in the above-mentioned ethanol contact method.
A liquid mainly containing ethanol, including both undenatured ethanol and denatured ethanol. The content of ethanol is 50% by weight or more, preferably 90% by weight or more, and more preferably 95% by weight or more.

The denatured ethanol is obtained by mixing a denaturant with ethanol. As a modifying agent to be mixed,
Synthetic chemicals and natural substances are included. These denaturants can usually be used in an amount of 1 g to 200 g per liter of ethanol.

As the synthetic chemical substances, those described above can be used. Among them, ethyl acetate, butyl paraoxybenzoate, white lac, purified shellac, a solution of white lac, and a solution of purified shellac are preferred as the denaturant.

Examples of the natural substance include those described above. They may be used alone, but are usually used as a mixture.

When obtaining purified lactide for use as a food additive, among these modifiers, flavors derived from natural substances usable as food additives are particularly preferred. More specifically, flavors H-1 and H- manufactured by Hasegawa Koran Co., Ltd.
2, H-3, H-4, H-6, H-9, H-10, H-
11, H-12, H-13, H-14, flavors T-100, T-101, T-1 manufactured by Takasago International Corporation
02, T-103, T-104, T-105, T-10
6, T-107, EDA-171, flavor S-201 manufactured by Soda Perfume Co., Ltd., and flavor DA-40 manufactured by Riken Perfumery Co., Ltd. can be used. What kind of denaturing agent is used is variously selected depending on the use of the food additive.

As ethanol, a mixture of water and water other than the denaturing agent can be used. The amount of water to be mixed is 0 to 10 parts by weight, preferably 0 to 5 parts by weight, more preferably 100 parts by weight of ethanol. Is from 0 to 0.1 parts by weight. If the amount exceeds 10 parts by weight, the yield of purified lactide decreases, which is not preferable. When obtaining purified lactide for use in food additives, it is of course preferable to use undenatured ethanol. Undenatured ethanol is ethanol in which a denaturant is not mixed.

In the ethanol recrystallization method, the amount of denatured ethanol or undenatured ethanol used for dissolution of crude lactide depends on the purity of crude lactide to be purified, the method of recrystallization, and the quality of purified lactide to be obtained. Can be set arbitrarily, but is usually 50 to 500 parts by weight, preferably about 100 to 200 parts by weight, per 100 parts by weight of crude lactide. If the amount of ethanol is less than 50 parts by weight,
It may take a long time to dissolve the crude lactide, the dissolution may be incomplete, or the purity of the purified lactide may deteriorate. On the other hand, when the amount of ethanol is more than 500 parts by weight, the yield of purified lactide becomes poor, and it is uneconomical to use a large amount of ethanol.

The dissolution of crude lactide in ethanol is usually
It is carried out while improving the solubility under heating. The heating temperature is generally 40 to 75C, preferably 50 to 70C, and more preferably 55 to 65C. When the heating temperature exceeds 75 ° C., lactide reacts with ethanol or water contained in ethanol, and the lactide yield tends to decrease. The operation of dissolving the crude lactide in ethanol can be performed in a batch system or a continuous system.

The dissolution of crude lactide is not particularly limited, but can be carried out using a vessel equipped with a stirrer. As a stirring device, for example, a double ribbon blade stirring device, a full zone blade stirring device, a disk turbine blade stirring device, a rotary blade stirring device such as a homomixer, a jet flow, a stirring device using a circulating flow, a stirring device using a static mixer, and the like are used. Can be

After dissolving the crude lactide in ethanol,
The lactide crystals precipitate. The precipitation of the crystals is usually performed by cooling and / or distilling off the solvent. That is, a method of lowering the saturation concentration by cooling, a method of lowering the amount of solvent by reducing a solvent amount by distilling a part of the solvent by heating, reducing pressure, or a method of distilling a part of the solvent by reducing pressure. In addition, a method is used in which the temperature of the solution is lowered by the latent heat of vaporization of the solvent to be distilled off to reduce the amount of the solvent and the saturation concentration. In addition, the lactide crystal precipitation operation can be performed in a batch system or a continuous system.

When lactide crystals are precipitated by cooling, the lactide is cooled to a temperature of usually 30 to -10 ° C, preferably 25 to 0 ° C, more preferably 20 to 5 ° C.

The apparatus for preferentially depositing lactide crystals is not particularly limited, but a vessel equipped with a stirrer and used for dissolving crude lactide in ethanol can be used. D. T. B-type crystallizer,
D. P. Crystallizer, crystal-oslo crystallizer,
A conical crystallizer, a turbulence crystallizer, or the like can be used.

The solid content is separated from the slurry mixture obtained by crystallization. Lactide can also be recovered from ethanol from which solids have been separated by crystallization, concentration, or the like.

The separation device is not particularly limited, but a centrifugal settler, a centrifugal filter, and a pressure filter can be used. When using a device that has the function of rinsing solids among these devices, perform both the operation of separating solids precipitated by the same device and the operation of rinsing the separated solids with ethanol. So you can
It is valid.

As a centrifugal sedimenter, a vertical basket type centrifugal sedimenter, a screw decanter type centrifugal sedimenter, or the like is used. As the centrifugal filter, a vertical basket type centrifugal filter, a screw decanter type centrifugal filter, a conical screen type centrifugal filter, or the like is used. As a pressure filtration device,
A gravity filter, a pressure filter, a vacuum filter, or the like is used.

The separated solid is washed with fresh ethanol as needed. By the washing operation, higher purity lactide can be obtained. Usually, the obtained solid after washing is dried to obtain a purified lactide.

The amount of ethanol used in this washing operation can be arbitrarily set, but is usually 10 to 300 parts by weight, preferably 20 to 150 parts by weight, per 100 parts by weight of solids.
More preferably, it is about 30 to 70 parts by weight. If the amount of ethanol is less than 10 parts by weight, it may not be possible to wash uniformly or the effect of removing impurities may be small. On the other hand, when the amount of ethanol is more than 300 parts by weight, the yield of purified lactide becomes poor, and the use of a large amount of ethanol is uneconomical.

In the present invention, the separated solid is preferably dried under reduced pressure. The lactide obtained as a solid content usually has the substances contained in the used ethanol, water and possibly denatured ethanol attached. These adhesions may deteriorate the fluidity of the obtained purified lactide particles or may cause a problem of the odor. Therefore, in order to reduce the attached substance, the solid content may be dried under reduced pressure.

The drying under reduced pressure is preferably carried out at a low temperature in order to suppress the decomposition of lactide due to the reaction with ethanol or water by heating.
° C, preferably about 10 to 60 ° C, 0.01 to 1
It can be performed at a pressure of about 00 Torr. Also,
Freeze-drying can also be performed at a pressure of about 0.001 to 10 Torr and a temperature of 0 ° C. or less. The drying time should be determined depending on the capacity of the drying apparatus, the amount of lactide to be dried, or the content of ethanol and water in the purified lactide to be obtained, but is usually 5 minutes to 10 hours.

In the case of heating and drying under reduced pressure, a tray dryer, a cylindrical stirring dryer, a conical rotary dryer, and the like can be used without limitation. When freeze-drying is performed, a shelf-stage dryer can be used without limitation.

(Utilization of Lactide as Food Additive) In the food field, glucono delta lactone has conventionally been used as a coagulant, a swelling aid and a food preservative. In the production of sake, shochu, and other lactic acid-containing alcoholic beverages and soft drinks, lactic acid fermentation is performed or lactic acid is added.

In the production of yogurt, cheese, etc.,
Conventionally, proteins are coagulated by lactic acid produced by lactic acid fermentation. However, from the viewpoints of productivity and quality stability, lactic acid and glucono delta lactone have been used.

However, (1) lactic acid fermentation takes too long a production time, (2) the pH drops suddenly when lactic acid is added, (3) glucono delta lactone is
There is a problem that decomposition is slightly faster.

Therefore, there is a demand for an additive whose decomposition is slightly slower than that of glucono delta lactone. Lactide degrades more slowly than glucono delta lactone, and the acid produced by the degradation is more preferably lactic acid than gluconic acid because it has the same acidity as natural lactic fermented foods.

That is, the present invention relates to an animal and / or vegetable protein coagulant, a foaming agent for food, a preservative for food,
It also relates to novel uses of lactide as a food additive such as conditioners and sour agents.

When lactide is used as a food additive, lactide is hydrolyzed to almost lactic acid when actually ingested. When using optically active L-lactide (LL-lactide), L
-L-lactic acid is compared to D-lactic acid.
There are the following advantages.

(A) It is known that lactic acid in the human body is L-form. (B) FAO & WHO recommends that L-lactic acid be used in food and Ringer's solution consumed by infants. (To
xicological evaluation ofcertain food additives wi
th a review of general principles and of specific
ations. World Health Organization, Geneva, p23 197
4) (C) D-2-hydroxy acid dehydro
There have been reports of brain damage in the absence of genase. (Oh, MS, Pheips, KR, Traube, M., Sald
iver, JLB, Boxhill, C., and Carroll, HJ (19
79) D-lactic acidosis in a man with the short-bo
wel syndrom. New Engl. J. Med., 301: 249-252)

The present invention is a food preservative containing lactide as a main component. In this food preservative, lactide preferably has optical activity. In this food preservative, the lactide having optical activity is preferably in the L-form. The optical purity of L-lactide is, for example, 70% ee or more, preferably 80% ee or more, and more preferably 90% ee or more. Here, the optical purity of L-lactide (% ee)
Is defined as 100 × (LD) / (L + D). The content of L-lactide with respect to the total amount of lactide is, for example, 85% by weight.
As described above, 90% by weight or more is preferable, and 95% by weight or more is more preferable.

Alternatively, in this food preservative, lactide having optical activity may be a D-form. The optical purity of D-lactide is, for example, 70% ee or more and 80% ee.
ee or more is preferable, and 90% ee or more is more preferable. Here, the optical purity (% ee) of D-lactide is 100 × (DL)
Defined as / (L + D). The content of D-lactide relative to the total amount of lactide is, for example, 85% by weight or more, 90% by weight.
Or more, more preferably 95% by weight or more.

In this food preservative, the amount of the linear lactic acid polymer contained in lactide is preferably 2.0% by weight or less. Lactide is more preferably lactic acid obtained by fermentation and synthesized from lactic acid having an optical purity of L-form or D-form of 90% ee or more. Lactide used as a food preservative may be obtained by the purification method of the present invention described above, or may be obtained by other methods.

[0100]

EXAMPLES The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples. [Synthesis Example 1 of Lactide] Lactic acid (Pu) was placed in a 2 L SUS separable flask equipped with a thermometer, stirrer, condenser, distillate receiver, decompression device, heating temperature control device, etc.
1000 g of HS-88 manufactured by rac: 88.1% by weight in terms of lactic acid monomer: 99.2% ee in optical purity. First, at 130 ° C. for 2 hours at normal pressure, and then 13
The temperature was gradually raised from 0 ° C. to 160 ° C. in 4 hours, and about 703 g of polylactic acid having a weight average molecular weight of 2150 as measured by GPC.
I got

To this low molecular weight polylactic acid was added 10.0 g of tin octylate, and the temperature was gradually increased from 160 ° C. to 200 ° C. under reduced pressure, and the crude lactide 690 was obtained in about 1 hour and 45 minutes.
g was distilled off and collected.

When the composition of the obtained crude lactide was analyzed by high performance liquid chromatography (HPLC), L-lactide and D-lactide: 92.54% by weight, meso-lactide: 3.29% by weight, linear lactic acid Dimer: 0.77% by weight, lactic acid: 3.40% by weight.

Example 1 (Ethanol Contact Method) The crude lactide obtained in Synthesis Example 1 was ground in a mortar and passed through a 10-mesh sieve. 50 g of crude lactide passed through this sieve and 15 g of 99 ° C. primary unmodified ethanol (fermented alcohol) at 25 ° C. were mixed in a beaker to obtain a slurry-like mixed solution, and the mixture was stirred with a stirrer for 15 minutes. The slurry was transferred to a glass filter (Buchner type, maximum pore size: 20 to 30 μm) mounted on the filter bottle, the pressure in the filter bottle was reduced by an aspirator for about 1 minute, and the liquid in the slurry was suction-filtered.

After suction filtration, the glass filter was newly added to 25 ° C.
99 degree 1st grade native ethanol (fermented alcohol) 1
5 g was added, the pressure in the filter bottle was reduced by an aspirator for about 1 minute, and suction filtration was performed. The separated solid was dried using a rotary evaporator at 40 ° C. and 4 Torr for 1 hour to obtain 43.9 g of purified lactide (purification yield: 87.8).
%).

When the composition of the obtained purified lactide was analyzed by HPLC, L-lactide and D-lactide: 98.2 were obtained.
1% by weight, meso-lactide: 1.18% by weight, linear dimer of lactic acid: 0.24% by weight, lactic acid: 0.37% by weight. The ethanol content of the purified lactide was determined to be 540 pp by gas chromatography (GC).
m, and a slight ethanol odor was felt. The water content of the purified lactide was 35 ppm as measured by a Karl Fischer moisture meter. The purified lactide was in the form of particles having good flowability, and was sealed at 20 ° C.
This fluidity was not lost even after storage in a tube for one month.

(Calculation of the amount of L-lactide in purified lactide) In the HPLC analysis of the purified lactide, the amount was measured as the total amount of L-lactide and D-lactide. This is because meso-lactide can be distinguished from D-lactide or L-lactide by this HPLC analysis method, but D-lactide and L-lactide could not be distinguished.

Then, the obtained purified lactide was hydrolyzed and analyzed by HPLC. As a result, the optical purity of L-lactic acid was 97.0% ee. Therefore, according to the following calculation, the concentration of L-lactide in the total lactide is 98.9% by weight or more. Here, the total lactide means the entire purified lactide, that is, the total of L-lactide, D-lactide, meso-lactide, L and D-lactic acid and lactic acid linear dimer.

(Calculation formula)-Concentration of L-lactide and D-lactide V wt%-Optical purity of L-lactic acid when hydrolyzed X% ee-Concentration of meso-lactide Y wt%-L and D-lactic acid Of the linear lactic acid linear dimer W can be obtained by measurement.

Further, the concentration of L-lactide was defined as A wt%, D
Bring the concentration of lactide to B% by weight. Here, in order to calculate the minimum concentration of L-lactide, it is assumed that lactic acid and the linear dimer are all D-forms.

The concentration of D-lactic acid when hydrolyzed is the following sum. The product derived from D-lactide is D-lactide 1 having a molecular weight of 144.
Because two molecules of D-lactic acid having a molecular weight of 90 are produced from the molecule;
(180/144) B wt% Meso-lactide-derived product produces one molecule of D-lactic acid having a molecular weight of 90 from one molecule of meso-lactide having a molecular weight of 144; (90/144) Y wt% lactic acid; Z wt% In the case of a product derived from a linear dimer, two molecules of D-lactic acid having a molecular weight of 90 are generated from one molecule of the linear dimer having a molecular weight of 162;
(180/162) W wt% Therefore, the concentration of D-lactic acid (D wt%) when hydrolyzed is D = (180/144) B + (90/144) Y + Z + (180/162) W ... .. (1)

On the other hand, the concentration (L wt%) of L-lactic acid when hydrolyzed is as follows: L-lactide-derived product; (180/144) A wt% Meso-lactide-derived product; (90/144) Y % By weight Therefore, the concentration of L-lactic acid (L% by weight) upon hydrolysis is as follows: L = (180/144) A + (90/144) Y (2)

Here, the optical purity X% ee of L-lactic acid is X
= 100 (LD) / (L + D). Substituting (1) and (2) into this, and since A + B = V, B
Is eliminated and A is solved. A = (1/2) V + (4/9) W + Y + (2/5) Z + (1/200) VX + (1/225) WX + (1/200) XY + (1 / 250) XZ .... (3) By substituting the measured values of V, X, Y, Z and W for (3), the concentration of L-lactide: A weight% is obtained.

Example 2 (Ethanol Contact Method) The crude lactide obtained in Synthesis Example 1 was ground in a mortar and passed through a 10-mesh sieve. 50 g of crude lactide passed through this sieve and 15 g of 99 ° C. primary unmodified ethanol (fermented alcohol) at 25 ° C. were mixed in a beaker to obtain a slurry-like mixed solution, and the mixture was stirred with a stirrer for 15 minutes. This slurry was transferred to a glass filter (Buchner type, maximum pore diameter: 20 to 30 μm) mounted on the filter bottle, and the filter bottle was depressurized with an aspirator for 1 minute, and the liquid in the slurry was suction-filtered.

After suction filtration, the glass filter was newly added to 25 ° C.
99 degree 1st grade native ethanol (fermented alcohol) 1
5 g was added, and the pressure in the filter bottle was reduced by an aspirator for 1 minute, followed by suction filtration. After suction filtration, add a new 25 ° C to the glass filter.
Of water was added, and the pressure in the filter bottle was immediately reduced by an aspirator, followed by suction filtration. The separated solid was dried using a rotary evaporator at 40 ° C. and 4 Torr for 2 hours to obtain 43.5 g of purified lactide (purification yield: 87.50 g).
0%).

When the composition of the obtained purified lactide was analyzed by HPLC, L-lactide and D-lactide: 98.2 were obtained.
3% by weight, meso-lactide: 1.11% by weight, lactic acid linear dimer: 0.27% by weight, lactic acid: 0.39% by weight. Further, the ethanol content of this purified lactide was
It was 34 ppm as measured by C, and almost no ethanol odor was felt. The water content of this purified lactide was measured with a Karl Fischer moisture meter.
ppm. Further, the purified lactide was in the form of particles having good flowability, and the flowability was hardly lost even after sealing and storing the tube at 20 ° C. for one month.

Example 3 (Ethanol Contact Method) (Synthesis of Lactide) Thermometer, stirrer, condenser
Lactic acid (Purac HS-8) was placed in a 1.3 kL reactor equipped with a distillate receiver, a decompression device, a temperature control device, and the like.
8: Lactic acid monomer equivalent concentration 88.1% by weight: Optical purity 9
(9.2% ee) 1000 kg was charged. First, normal pressure,
3 hours at 130 ° C, then gradually from 130 ° C under reduced pressure for 6 hours
The temperature was raised to 160 ° C. over a period of time to obtain about 702 kg of polylactic acid having a weight average molecular weight of 2490 as measured by GPC.

To this low molecular weight polylactic acid was added 10.0 kg of tin octylate, and the temperature was gradually increased from 160 ° C. to 200 ° C. under reduced pressure, and 697 kg of crude lactide was obtained in about 3 hours.
Was distilled off and collected. The composition of the obtained crude lactide was determined by HPL
When analyzed by C, L-lactide and D-lactide: 9
1.93% by weight, meso-lactide: 4.18% by weight, linear dimer of lactic acid: 0.64% by weight, lactic acid: 3.25% by weight.

(Purification of lactide) Capacity 1.8 k with disk turbine blade stirring device, thermometer, temperature control device, etc.
530L (418.2kg) 99 degree 1
Grade native ethanol (fermented alcohol)
Cooled to 0 ° C. Mixing tank with disk turbine blade 60r
While stirring at pm, the entire amount of the crude lactide obtained in the above synthesis is maintained in a molten state (103 ° C.), and a four-hole nozzle (each having a diameter of 2 m) capable of discharging in the form of a shower.
m), it was supplied at a discharge rate of about 10 L per minute in about 60 minutes.

While feeding the crude lactide in the molten state,
Cooling was performed by a temperature controller to prevent the temperature inside the mixing tank from rising, but the internal temperature at the end of the supply was 32 ° C due to insufficient cooling capacity.
It became. After the end of the supply, stirring and temperature control (set temperature 20
° C) was continued. One hour after the completion of the supply, the internal temperature was 20 ° C.

One hour after the completion of the supply, about 1/5 of the slurry in the mixing tank was supplied to a vertical basket-type centrifugal filter having a basket diameter of 1000 mm and a basket depth of 400 mm in about 90 seconds. Was isolated. The rotation of the basket during slurry supply was 300 rpm.

After the supply of the slurry is completed, the rotation speed of the basket is set to 800 rpm in order to further improve the separation of the solid content.
And the liquid was removed for 10 minutes. After the drainage, the rotation speed of the basket was lowered to 500 rpm, and 99% first-grade undenatured ethanol (fermented alcohol) at 20 ° C. was discharged in a spray form from a spray nozzle for rinsing liquid supply, and 71 L of water was discharged.
(56.0 kG) was supplied in about 120 seconds, and fresh ethanol was brought into contact with the solid content in the basket, and at the same time, the solid content was separated.

After the supply of ethanol was completed, the rotation speed of the basket was increased to 800 rpm in order to further improve the solid content separation.
m, and the liquid was removed for 10 minutes. After the completion of the liquid removal, the solid content in the basket was scraped off and charged into a conical rotary dryer (double cone dryer) having a tank volume of 1.1 kL.

Thereafter, the operation from the supply of the slurry to the centrifugal filter to the introduction of the solid content to the conical rotary dryer was repeated four times, and the entire amount of the slurry in the mixing tank was processed. The conical rotary dryer was rotated at 10 rpm, and the charged solid content was dried at a temperature of 50 ° C. and a pressure of 2 Torr for 6 hours to obtain 611 kg of purified lactide (purification yield: 87.0%).

When the composition of the obtained purified lactide was analyzed by HPLC, L-lactide and D-lactide: 98.7 were obtained.
6% by weight, meso-lactide: 0.82% by weight, linear dimer of lactic acid: 0.19% by weight, and lactic acid: 0.23% by weight. Further, the ethanol content of this purified lactide was
It was 360 ppm when measured by C, and a slight ethanol odor was felt. The water content of the purified lactide was measured by a Karl Fischer moisture meter to be 21 ppm. The purified lactide was in the form of particles having good flowability, and the flowability was not lost even after the tube was sealed and stored at 20 ° C. for 1 month.

Example 4 (Native ethanol recrystallization method) 200.0 g of the crude lactide obtained in Synthesis Example 1 above
And 200.0 g of undenatured ethanol were mixed, and the resulting mixture was heated to 70 ° C. with stirring to completely dissolve the crude lactide. The obtained solution was cooled to 15 ° C. while stirring to precipitate lactide to obtain a slurry.

This slurry was transferred to a glass filter (Buchner type, maximum pore size: 20 to 30 μm) mounted on the filter bottle, the pressure in the filter bottle was reduced by an aspirator for about 2 minutes, and the liquid in the slurry was suction-filtered. The separated solids were separated using a rotary evaporator at 60 ° C. and 10 Torr for 2 hours.
After drying for 14 hours, 144.9 g of purified lactide was obtained.

When the composition of the obtained purified lactide was analyzed by HPLC, L-lactide and D-lactide: 99.6 were obtained.
5% by weight, meso-lactide: 0.24% by weight, lactic acid linear dimer: 0.03% by weight, lactic acid: 0.00% by weight. The water content of the purified lactide was 27 ppm as measured by a Karl Fischer moisture meter. The purified lactide was in the form of particles having good flowability, and the flowability was not lost even after the tube was sealed and stored at 20 ° C. for 1 month.

(Calculation of L-lactide content in purified lactide) The obtained purified lactide was hydrolyzed,
Upon C analysis, the optical purity of L-lactic acid was 99.3% ee.
Met. Therefore, the concentration of L-lactide in the total lactide is 99.6% by weight or more as in the calculation in Example 1.

[Example 5 (denatured ethanol recrystallization method)]
Flavor H-11 manufactured by Hasegawa Koryo Co., Ltd. as a modifier
Used denatured ethanol mixed with 5.0 g per 1 L of 99 degree 1st grade fermentation ethanol. The crude lactide 2 obtained in Synthesis Example 1 above was added to 300.0 g of the denatured ethanol.
00.0 g were mixed. The resulting mixture was heated to 60 ° C. with stirring to completely dissolve the crude lactide.

The obtained solution was cooled to 15 ° C. with stirring to precipitate lactide to obtain a slurry. Glass filter (Buchner type, maximum pore size 20
ス ラ リ ー 30 μm), the pressure in the filter bottle was reduced by an aspirator for about 2 minutes, and the liquid in the slurry was suction-filtered.

After suction filtration, the glass filter was newly added to 15 ° C.
99 degree 1st grade denatured ethanol (fermented alcohol) 10
0 g was added, the pressure in the filter bottle was reduced by an aspirator for about 2 minutes, and suction filtration was performed. The separated solid was dried using a rotary evaporator at 40 ° C. and 4 Torr for 2 hours to obtain 161.2 g of purified lactide.

When the composition of the obtained purified lactide was analyzed by HPLC, L-lactide and D-lactide: 99.7 were obtained.
2% by weight, meso-lactide: 0.18% by weight, linear dimer of lactic acid: 0.02% by weight, lactic acid: 0.00% by weight. The water content of the purified lactide was 22 ppm as measured by a Karl Fischer moisture meter. The purified lactide was in the form of particles having good flowability, and the flowability was not lost even after the tube was sealed and stored at 20 ° C. for 1 month.

(Calculation of L-lactide content in purified lactide) The obtained purified lactide was hydrolyzed,
According to C analysis, the optical purity of L-lactic acid was 99.4% e.
e. Therefore, the concentration of L-lactide in the total lactide is 99.7% by weight or more, as in the calculation in Example 1.

In the following Example 6, the purified lactide obtained in Example 1 was used.

Example 6 (Utilization of Lactide as Food Preservative) Using a custard cream for testing, the effect of preserving food by adding lactide was examined. (Blend) Milk 1200ml Egg 750g Sugar 500g Flour 80g Corn starch 90g

The material mixed in the above composition was divided into four equal parts, and 0% by weight (no addition) of lactide, 0.2%
5% by weight, 0.5% by weight, and 1% by weight were added, and processed in a conventional manner to prepare a test custard cream. Each test custard cream was placed in a thermostat at 35 ° C., sampled at regular intervals, and the number of general viable bacteria in 1 g was examined. Table 1 shows the results. Table 1 shows that the addition of lactide suppressed the growth of bacteria.

[0137]

[Table 1]

The present invention may be embodied in various other forms without departing from its spirit or essential characteristics. Therefore, the above-described embodiment is merely an example in every aspect, and should not be construed as limiting. Furthermore, all modifications belonging to the equivalent scope of the claims are within the scope of the present invention.

[0139]

As described above, according to the present invention, a purified lactide having a high content of L-lactide and / or D-lactide can be obtained in a short time and in a high yield by a simple apparatus and operation. Can be. Further, according to the present invention, a purified lactide having good workability can be obtained without leaving an organic solvent harmful to the human body.

The purified lactide obtained according to the present invention is inexpensive and suitable for use in food additives. According to the present invention, a food preservative containing lactide as a main component is provided.

Claims (8)

[Claims] 1. A food preservative containing lactide as a main component. 2. The method according to claim 1, wherein the lactide has optical activity.
A food preservative according to item 1. 3. The food preservative according to claim 2, wherein the lactide having optical activity is an L-form. 4. The food preservative according to claim 3, wherein L-lactide is at least 85% by weight based on the total amount of lactide. 5. The food preservative according to claim 2, wherein the lactide having optical activity is a D-form. 6. The food preservative according to claim 5, wherein D-lactide is at least 85% by weight based on the total amount of lactide. 7. A lactic acid monomer contained in lactide and / or
Or the food preservative according to any one of claims 1 to 5, wherein the amount of the linear lactic acid polymer is 2.0% by weight or less. 8. Lactide is fermented lactic acid,
The food preservative according to claim 1, which is synthesized using lactic acid having an optical purity of L-form or D-form of 90% ee or more as a raw material.