JP2756571B2 - Method for producing granular dipeptide sweetener - Google Patents

Description

The present invention relates to a method for producing a granular dipeptide sweetener, and more particularly to α-L-aspartyl-L-.
The present invention relates to a method for producing a granular dipeptide sweetener having good fluidity and solubility from a slurry liquid of phenylalanine alkyl ester.

[Prior Art] Dipeptide sweeteners represented by lower alkyl esters of α-L-aspartyl-L-phenylalanine, especially methyl esters, have already become important as low-calorie sweeteners.

The dipeptide sweetener is generally used as an aqueous solution or, if necessary, together with other components, in the form of a powder, a tablet or the like.

Compounds used as dipeptide sweeteners, such as α
-L-Aspartyl-L-phenylalanine methyl ester is produced industrially once in the form of a powder or the like in view of its storage stability. However, since the solid of α-L-aspartyl-L-phenylalanine methyl ester obtained by a conventional method has a low dissolution rate in water, a dipeptide having good solubility in the industry for producing a product containing such a sweet component as an aqueous solution. Sweeteners are required.

Even when the dipeptide sweetener is used in the form of a powder, the sweetness is exhibited only when dissolved in water, so that a dipeptide sweetener that rapidly dissolves in water is required.

For this reason, various attempts have been made to improve the solubility in water. These attempts are roughly 2
One is to improve the crystal structure of the sweetener by changing the crystal structure, and the other is to change the shape of the dried sweetener.

Examples of the former include JP-A-63-44593 and others. Although this method can be expected to have a considerable effect, it is limited only to a certain extent due to the chemical and physical properties of the α-L-aspartyl-L-phenylalanine alkyl ester molecule. Not enough. This is because the dissolution rate is greatly affected by the properties of the dried sweetener powder even in the crystal structure having improved solubility.

A prior art example of the latter method to which the present invention also belongs is U.S. Pat. No. 4,517,2145 / 1985, Shoaf et al. Although this method is also effective as a method for producing a dried α-L-aspartyl-L-phenylalanine alkyl ester product having a high purity, it is very difficult to use a wet pulverization operation, particularly an ultrafine pulverizer, as a food additive. It is difficult and requires high technology.

[Problems to be Solved by the Invention] In general, when a dried product is industrially produced in a large amount from a slurry liquid and a high dissolution rate is required for the product, spray drying is regarded as the most superior method. In other words, considering that the raw material is dried by this method, the product becomes porous spherical and improvement in solubility and solubility can be expected,
When drying in large quantities, the surface area per unit to-be-dried becomes very large, so there is an advantage that the spray dryer is very excellent in drying efficiency compared to other dryers and is economically advantageous. .

A first obstacle in implementing this method is that when attempting to obtain spherical particles, the solid particles constituting the raw material slurry must be much smaller than the product particles. Given the practical size of the spray dryer, the product particles have a maximum diameter of several hundred micrometers, preferably
When the product is to be made porous and spherical, the particles constituting the slurry must be preferably 20% or less, particularly preferably 5% or less with respect to the product diameter in order to make the product porous spherical. On the other hand, α-L-aspartyl-L, which constitutes the slurry of the spray raw material,
-It is clear that wet grinding is necessary in view of the crystal size of the phenylalanine alkyl ester, but in the current technology, to grind to this size, a medium-stirring grinder must be used. In principle, the crusher cannot avoid wear of the crushing medium, and requires various devices to prevent the wear.

If the pulverization operation is not performed, the shape of the spray-dried product becomes a long spindle yarn with the core of large α-L-aspartyl-L-phenylalanine alkyl ester crystals present in the spray raw material slurry, and is broken during drying. In this case, the amount of fine particles (several micrometers) increases, and the fluidity of the product is significantly deteriorated.

As a second obstacle, the crystals of the α-L-aspartyl-L-phenylalanine alkyl ester have water of crystallization or adhered water, and the drying time is very short, and the air humidity near the outlet of the dryer becomes very high. It is extremely difficult to dry to the required moisture content. In order to solve this problem, setting a high temperature of the exhaust air for spray drying is effective in lowering the water content. However, it produces crystals of a type having poor solubility and α-L.
-Aspartyl-L-phenylalanine alkyl ester is known to be impractical due to poor thermal stability.

An object of the present invention is to provide a method for easily producing an α-L-aspartyl-L-phenylalanine alkyl ester sweetener having high purity and good fluidity and solubility which has been difficult to obtain conventionally. .

[Means for Solving the Problems] The inventors of the present invention have conducted intensive studies to solve the above-mentioned problems, and as a result, by performing a fluid granulation operation of spraying a co-liquid after spray drying, difficult fine pulverization is performed. The operation was eliminated, and the α-L-aspartyl-L-phenylalanine alkyl ester sweetener granules having good fluidity and solubility were successfully produced.

The gist of the present invention is to spray-dry without using a pulverizing operation, then granulate, and then, if necessary, dry to obtain α-L-aspartyl-L having high purity and good fluidity and solubility.
-To easily produce a phenylalanine alkyl ester sweetener. That is, in the present invention, a slurry liquid containing crystals of α-L-aspartyl-L-phenylalanine lower alkyl ester is spray-dried without pulverization, and the obtained dried product is granulated and dried again if necessary. The present invention provides a method for producing a granular dipeptide sweetener characterized by the following. The details will be described below.

The slurry to be dried used in the present invention has relatively large particles, but when crystals are precipitated for the purpose of purification operation from a complete solution, the crystals form needle-like crystals due to the cohesive force of the crystals, and have a long diameter. It will be more than 50 micrometers. In the present invention, the slurry is spray-dried as it is or re-pulp with water added for easy spraying, that is, without pulverizing operation.
The product obtained here is sufficiently free of foreign matter due to pulverization. However, since it is spindle-shaped and contains a large amount of fine powder, its flowability is extremely poor, and the water content is usually 4 to 10% of the product. is there.

Next, in the present invention, a granulation operation, preferably a flow granulation operation and, if necessary, a drying operation are performed. The spray liquid used in the fluidized-granulation operation is water, an aqueous solution of α-L-aspartyl-L-phenylalanine alkyl ester, a sugar solution, and an aqueous solution (including a slurry) of other conceivable binders. Can be used for fluid drying, vacuum drying and the like. However, in order to prevent the destruction of the granulated material, the direction in which the material to be dried moves as little as possible is preferable.

Example 1 A slurry in which crystals were precipitated from an aqueous solution of α-L-aspartyl-L-phenylalanine methyl ester was concentrated by a solid-liquid separation operation, repulped while adding water cooled to 4 ° C., and spray-dried. The slurry was prepared. The constituent particles of this raw material slurry were agglomerates of needle-like crystals and had a length of about 200 to 30 micrometers. This slurry was spray-dried at an inlet temperature of 170 ° C. and an outlet temperature of 75 ° C., and all products were recovered. The obtained product shows a particle size distribution with two peaks, large and small, such as around 75 micrometer and 5 micrometer in volume average diameter. Is the large α-L-aspartyl-L present in the spray raw material slurry.
-A long spindle yarn with phenylalanine methyl ester crystals as nuclei. This product is 1.0% α-
Fluid granulation was performed for 10 minutes while spraying an aqueous solution of L-aspartyl-L-phenylalanine methyl ester.

Further, spraying was stopped by the same machine, and fluid drying was performed for 10 minutes. The resulting product had a particle size distribution and physical properties as shown in the following table.

From Tables 1 and 2, it can be seen that the particle size distribution became extremely sharp due to the granulation and the fluidity was greatly improved.

[Effect of the Invention] In this method, when spray-dried, the product is spindle-shaped and contains a large amount of fine powder of 10 μm or less, so that the fluidity is extremely poor, and the water content is 4 to 10%.
It is 10%, which is extremely unsatisfactory as a food additive. However, by subjecting this product to fluid granulation and drying as needed, the spindle-shaped product and a large amount of fine powder are agglomerated and granulated. Is 2-4% of the product. This product is excellent as a food additive.

Claims (1)

(57) [Claims] 1. A method of spray-drying a slurry liquid containing crystals of α-L-aspartyl-L-phenylalanine lower alkyl ester without pulverization, granulating the resulting dried product, and re-drying as required. A method for producing a granular dipeptide sweetener, comprising: