JPS588374B2 - Apple Sandisodium Ensuiwabutsuno Kansouhouhou - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention involves drying wet d-1-malic acid disodium salt trihydrate to obtain d-1-malic acid disodium salt hydrate having a water content of 10% or less. Relating to a method of manufacturing.

Disodium salt of malic acid is a well-known compound with uses such as salt-free soy sauce, food processing additives, and buffering agents.

Disodium d-1-malate has a very high solubility in water and forms several types of hydrates, which causes various difficult problems when producing disodium malate on an industrial scale. encounter.

According to Japanese Patent Publication No. 48-9530, in order to crystallize d-1-disodium malate as a monohydrate, it is necessary to evaporate it to 110 to 130°C, cool it to 30°C, and leave it still. ing.

The disadvantages of this method are that it takes a long time for crystallization, the fluidity of the crystallized slurry is poor, and because the solution is left to stand still, the entire solution often turns into ice-like hard crystals, making it difficult to post-process. This is extremely disadvantageous from an industrial perspective.

To avoid this difficulty, it is industrially advantageous to obtain a fluid crystal slurry by cooling and crystallizing a concentrated aqueous solution of disodium malate while stirring.

In particular, d. -1- When an aqueous solution containing 50% or more of disodium malate is cooled with stirring and crystallized, d
- The trihydrate of 1-malic acid disodium salt is obtained.

These crystals can be easily separated from the mother liquor using a centrifuge or filter to obtain wet crystals containing free water.

When drying the wet crystals in a box dryer, the temperature is 70°C.
If the temperature is kept above this level, it will solidify or sinter.
Furthermore, it becomes a springy, candy-like aqueous solution, which slows down the drying speed, and even if drying is continued, only the surface dries and the inside remains undried, and if this is pulverized, problems such as clogging the pulverizer will occur.

To solve this problem, when drying the wet crystals of the trihydrate of d-1-malic acid disodium salt, the drying temperature should not be set above 70°C from the beginning, but first the drying temperature should be set at a temperature below 70°C.
Wet d-1-malic acid disodium salt trihydrate is obtained by employing a stepwise drying method in which the moisture content is reduced to a certain level by stage drying, and then reduced to the desired moisture content by second stage drying at 70°C or higher. The product can advantageously be dried to d-1-malic acid disodium salt hydrate without solidification or semi-melting.

The present inventor further developed this method and conducted intensive research to simplify the drying process by directly drying wet d-1-malic acid disodium salt trihydrate in one step at a temperature of 70°C or higher. As a result, wet d-1-malic acid disodium salt 3
If d-1-malic acid disodium salt hydrate, which has already been dried and has a water content below a certain amount, is mixed with the hydrate at a certain ratio and then dried at 70°C or higher, solidification or Desired moisture content without half-melting, especially moisture content of 10%
It was discovered that the following d-1-malic acid disodium salt hydrate could be produced, and the present invention was achieved.

The method of the present invention involves drying wet malic acid disodium salt trihydrate crystals obtained by crystallization and separation under stirring from an aqueous solution containing 50% or more disodium malate to have a water content of 10%.
In producing the following malic acid disodium salt hydrate, 70 to 40 parts of wet malic acid disodium salt trihydrate with a water content of 23 to 31% (including hydration water), and a water content of 10 parts % or less, add 30 to 60 parts of dried malic acid disodium salt hydrate, mix well, and then dry at 70 to 120°C to produce malic acid disodium salt hydrate with a water content of 10% or less. It consists of

The dryer used in the method of the present invention may be of any type as long as it is a dryer commonly used industrially and the drying temperature can be adjusted.

The wet malic acid disodium salt hydrate used in the method of the present invention is usually obtained by the following method and mainly consists of trihydrate and free water.

After reacting d-1-malic acid with sodium hydroxide, sodium hydrogen carbonate, or sodium carbonate in an aqueous solvent, an aqueous solution containing 50 to 60% of d-1 disodium malate is prepared. 5-45℃ under stirring
It is possible to crystallize the product while cooling to a temperature of 100.degree. C., followed by filtration or centrifugation to obtain wet malic acid disodium salt trihydrate as a filter cake.

The viscosity of the aqueous solution increases when the concentration reaches 60 to 75%, so it is necessary to use a more powerful stirrer than a normal stirrer.
Crystallize, filter or centrifuge, or cool under vigorous stirring.
After crystallization, it can be crushed to obtain wet malic acid disodium salt trihydrate crystals.

The wet d-1-malic acid disodium salt hydrate obtained by the above method is estimated to be a trihydrate because the water content does not change around 23.3% when dried at room temperature to 50°C. be done.

In addition, regarding the hydrate of malic acid disodium salt, +
Hydrates, hydrates, dihydrates, and tetrahydrates are well known (see Official Food Additives Standards, Chemical Dictionary), and trihydrates are not found in the literature, but their water content is calculated based on calculations. , 23.3%, which is almost the same as the water content when the wet d-1-malic acid disodium salt hydrate is dried at 50°C to a constant weight, so it is considered as a trihydrate. handled.

The wet d-1-malic acid disodium salt trihydrate obtained by the above method usually has a water content in the range of 23 to 31%.

To 70 to 40 parts of the wet d-1-malic acid disodium salt trihydrate with a water content of 23 to 31%, d-1-malic acid disodium salt trihydrate that has already been dried to a water content of 10% or less. After adding 30 to 60 parts of Japanese compound and mixing well,
Dry at 70-120°C.

In this case, it is not appropriate to use less than 30 parts of d-1-malic acid disodium salt hydrate with a water content of less than 10% because there is a risk of sintering when drying at 70° C. or higher.

The drying temperature in the method of the present invention is 70 to 120°C, and if it is below 70°C, it will take a long time to dry, and if it is above 120°C, there is a risk that the d-1-disodium malate will deteriorate, so especially above 180°C. When this happens, intramolecular condensation, bimolecular condensation, etc. occur.

Further, for the purpose of obtaining d-1-malic acid disodium salt close to anhydride, the temperature is preferably 100°C or higher.

Although drying in the method of the present invention can be carried out under normal pressure, it is advantageous to carry out the drying under reduced pressure in order to increase the drying rate.

Hereinafter, a detailed description will be given based on examples.

In addition, in the specification, "moisture content" is a percentage of the wet basis of free water and hydrated water, "1%" is a percentage by weight unless otherwise specified, "part" is a part by weight, and "sinter" is a percentage by weight. represent half-melting, respectively.

In addition, the moisture content was measured by the Karl Huitscher method.

Example 1 d・■-60°C containing 60% disodium malate
The aqueous solution of is cooled to 30° C. with stirring to cause crystallization.

After 6 hours, it was centrifuged and the wet d-
Crystals of 1-malic acid disodium salt 3 aqueous phase were obtained.

The wet d-1-malic acid disodium salt trihydrate 6
5 parts of the already dried d-1- with a moisture content of 6.8%
The mixture was thoroughly mixed with 35 parts of malic acid disodium salt crystals, placed on a metal pallet to a thickness of 3 cm, placed in a ventilation box dryer, and kept at 70°C for 5 hours. The water content of 1-malic acid disodium salt is 9
．． It was 5%.

Example 2 50 parts of the wet d-l-malic acid disodium salt trihydrate with a water content of 285% obtained in Example 1 was mixed with already dried d-1- with a water content of 6.8%. Mix well with 50 parts of malic acid disodium salt crystals and place on a metal pallet to a thickness of 3.
When the mixture was placed in a dryer and maintained at 80° C. for 5 hours in the same manner as in Example 1, the moisture content of the dried d-1-malate was 87%.

Example 3 40 parts of wet d-1-malic acid disodium salt trihydrate with a water content of 28.5% obtained in Example 1 and dry d-1-malic acid obtained in Example 2 Disodium salt moisture content 8
．． When 60 parts of 7% were mixed well and placed in a dryer as in Example 1 and kept at 90°C for 5 hours, the obtained dry d
The moisture content of disodium -1-malate was 76%.

When this was further held at 115°C for 2 hours, the d-
The water content of 1-monolic acid disodium salt was 6.9%.

Comparative Example 75 parts of the wet d-1-malic acid disodium salt trihydrate with a water content of 28.5% obtained in Example 1 was mixed with a water content of 6.8%.
% of d-1-malic acid disodium salt, placed on a metal pallet to a thickness of 3 cm, placed in a ventilation box dryer, and kept at 70°C for 1 hour, the whole solidified. The bottom of the pallet became candy-like and could not be dried.

Claims (1)

[Claims] 1 Dry the wet disodium malate salt trihydrate crystals obtained by crystallization and separation under stirring from an aqueous solution containing disodium malate of 50% or more to obtain disodium malate salt hydrate with a water content of 10% or less. When manufacturing products, moisture content 2
For 70 to 40 parts of wet malic acid disodium salt trihydrate of 3 to 31% (including water of hydration), the water content is already 1.
3 of malic acid disodium salt hydrate dried to 0% or less
Add 0 parts to 60 parts, mix well, and then add 70 to 12 parts.
1. A method for drying disodium malate salt hydrate, the method comprising drying at 0° C. to obtain disodium malate salt hydrate having a water content of 10% or less.