JPH07103155B2 - Method for producing stable α-L-aspartyl-L-phenylalanine methyl ester - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing α-L-aspartyl-L-phenylalanine methyl ester (hereinafter, referred to as aspartame) having excellent storage stability. It is a thing.

[Prior Art] Aspartame has two types of crystal forms, type I and type II, and type I crystals easily absorb moisture and
Although it tends to be colored and decomposed, the type II crystal is said to have low hygroscopicity, good fluidity and good storage stability.

Conventionally, a method for obtaining aspartame type II crystal by drying wet aspartame crystal at 80 ° C. or higher (JP-A-59-172441)
And JP-A-60-37949) or to obtain a granulated product, dried I
Add water to form I crystals to a water content of 35-45%,
A method of extrusion-granulating and re-drying it (JP-A-59-95)
862) etc. are known.

[Problems to be Solved by the Invention] In order to obtain a type II crystal, since a conventional method involves drying at a high temperature, a decomposition product of aspartame, that is, a diketopyrazine derivative is likely to occur. In order to obtain a granulated product, it is disadvantageous in terms of process control and energy cost, such as once watering a type II crystalline aspartame dried product, then granulating and re-drying.

An object of the present invention is to solve these problems and to provide a method capable of producing aspartame excellent in storage stability without the conventional high temperature drying and re-drying.

[Means and Actions for Solving Problems] The inventors of the present invention have conducted extensive studies in order to solve these problems, and found that aspartame of the I-type crystal contains water in a specific amount or more. It has been discovered that by drying with air it is possible to produce stable aspartame without hot drying as well as re-drying.

That is, according to the present invention, a wet crystal of α-L-aspartyl-L-phenylalanine methyl ester is dried to obtain a dried α.
A method for producing -L-aspartyl-L-phenylalanine methyl ester, characterized by comprising drying using air having an absolute humidity of 0.015 Kg / Kg or more.
The present invention provides a method for producing L-aspartyl-L-phenylalanine methyl ester.

The wet aspartame crystals before being dried according to the method of the present invention may be produced using any crystallization method and separation method.For the method for producing wet aspartame crystals,
It doesn't matter at all.

The wet aspartame crystals obtained may or may not be treated with a granulator. Also when treating with a granulator, any type of granulator such as extrusion granulation or compression granulation may be used.

When the wet aspartame crystals are extruded using an extrusion granulator, a columnar granulated product can be obtained by passing through a screen having a diameter of 0.1 to 10.0 mmφ. It is preferable to pass a screen having a diameter of 1.0 to 4.0 mmφ.

The drying of wet aspartame crystals in the method of the present invention is not particularly limited with respect to temperature and drying method. However, since drying at high temperature produces a diketopiperazine derivative, which is a decomposition product of aspartame, it is desirable to perform drying at less than 80 ° C.

An ordinary dryer may be used, but an aeration dryer, a fluidized dryer or the like, which allows a long residence time, is preferable.

For drying, use air with absolute humidity of 0.015 kg / kg or more. In order to obtain stable aspartame, that is, type II crystal of aspartame, it is preferable to use air having the highest possible humidity because it is preferable that the internal water vapor partial pressure is high during drying.

[Example] In the Examples, the ratio of the type II crystal (%, ratio of the type II crystal to the total amount of the type I crystal and the type II crystal) was measured by preparing a mixture of standard samples of the type I and type II and subjecting the mixture to X-ray irradiation. Bending angle (2θ) 4.4 ° (I
Type) and 5.0 ° (type II), a calibration curve was created from the intensity ratios of the respective characteristic peaks, and the ratio was determined from the intensity ratio of each sample and this calibration curve.

Examples 1 to 6 Wet aspartame crystals, which were solid-liquid separated by a centrifuge, 2.
It was passed through a 0 mmφ diameter screen and extruded and granulated.

The obtained wet aspartame granules (60 g) were dried with an aeration dryer using hot air (hot air flow rate 1 m / sec). The water content and type II ratio (%) of the obtained dried aspartame crystals were measured. The results are shown in Table 1.

[Effects of the Invention] As is apparent from the above description, according to the present invention, a type II crystal of aspartame excellent in storage stability, which was considered to be unmanufacturable by heating at a temperature of less than 80 ° C by the conventional method, was produced in It can be obtained without drying at an extremely high temperature, or without performing operations such as re-drying, which is disadvantageous in terms of process control and energy and cost.

The stable aspartame obtained by the method of the present invention is
It is particularly useful when granulated or tableted together with other substances such as sugars such as tabletop sweeteners.

Claims (7)

[Claims] 1. A dry α-L-aspartyl-L-phenylalanine methyl ester is obtained by drying wet crystals of α-L-aspartyl-L-phenylalanine methyl ester.
In the method for producing L-aspartyl-L-phenylalanine methyl ester, a stable α-L characterized by being dried using air having an absolute humidity of 0.015 kg / Kg or more.
-Method for producing aspartyl-L-phenylalanine methyl ester. 2. The production method according to claim 1, wherein the drying is performed at a temperature of less than 80 ° C. 3. The production method according to claim 1 or 2, wherein the wet crystals of α-L-aspartyl-L-phenylalanine methyl ester are granulated products treated with a granulator. 4. The method according to claim 3, wherein the granulated product has a diameter of 0.1 mm to 10.0 mm. 5. The production method according to claim 1 or 2, wherein the wet crystals of α-L-aspartyl-L-phenylalanine methyl ester are not treated with a granulator. 6. The method according to any one of claims 1 to 5, wherein the drying is carried out by a fluid dryer. 7. The method according to any one of claims 1 to 5, wherein the drying is carried out by using an aeration dryer.