JPS5822018B2 - Apple Sandisodium Ensuiwabutsuno Kansouhou - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides wet d,,ff-malic acid dinathoic acid sodium salt trihydrate having a moisture content of 15% or less.
- A method for producing IJ malate resin sodium salt hydrate.

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,t-malate has a very high solubility in water and forms several types of hydrates, so when disodium malate is produced on an industrial scale, various difficult problems are encountered in the process. .

According to Japanese Patent Publication No. 43-9530, in order to crystallize d,t-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 to crystallize, and the fluidity of the crystallized slurry is poor, and the entire solution often becomes ice-like solid crystals because it is left to stand still. However, it also has its drawbacks and 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, when an aqueous solution containing disodium d,7-malate of 50 parts or more is cooled with stirring and crystallized, d,
A trihydrate of t-malic acid disodium salt is obtained.

The crystals are separated from the mother liquor using a centrifuge and a filter to obtain wet crystals containing free water.

When drying the wet crystals or the d, t-IJ malate resin sodium salt trihydrate from which free water has been removed, if the humidity is kept at 70°C or higher, it will solidify or sinter, or even become candy-like. becomes an aqueous solution, and the drying speed decreases.
Even if drying is continued, only the surface will be dry and the inside will remain undried, and if this is crushed, problems such as clogging of the crusher will occur.

As a result of intensive research to solve these drawbacks, d, t-
! When drying the wet crystals of the trihydrate of disodium maltic acid salt, the drying temperature should not be set above 70°C from the beginning, but the water content should be reduced to a certain level in the first stage of drying at 70°C or below, Then, by adopting a stepwise drying method in which the moisture content is reduced to the desired level in the second stage of drying at 70°C or higher, wet d,t-IJ malic acid dinatriudisodium salt trihydrate or semi-melted material is obtained. The inventors have now found that it is possible to advantageously dry d with a water content of 15% or less to form malic acid disodium salt hydrate, and have arrived at the present invention.

The method of the present invention involves drying wet malate disodium salt trihydrate crystals obtained by crystallization and separation under stirring from an aqueous solution containing disodium malate with a water content of 15 parts or less. In producing acid disodium salt hydrate, the crystals with a water content of 23 to 31% (including water of hydration) are
After drying at 5 to 60°C to reduce the moisture content to 20% or less,
This method consists of drying malic acid disodium salt hydrate at a temperature of ~120°C to a moisture content of 15% or less.

The type of dryer used in the method of the present invention does not matter as long as the temperature can be adjusted.

Wet malic acid cinal-IJ salt hydrate in the method of the present invention is usually obtained by the following method and mainly consists of trihydrate and free water.

d,,ff-malic acid and sodium hydroxide l) rum. After reacting with sodium bicarbonate or sodium carbonate in an aqueous solvent, 50% of d,,ff-IJ disodium malate was added.
An aqueous solution containing ~65% salt is prepared, and this aqueous solution is crystallized while being stirred and cooled to 5 to 45°C, and then filtered or centrifuged to obtain wet malic acid disodium salt trihydrate as a filtrate cake. Obtainable.

d,,ff - In the case of an aqueous solution containing 60% or more of disodium malate, the viscosity of the aqueous solution will increase as crystallization occurs, so stir strongly and crystallize at a temperature below 30°C, filter or centrifuge, and moisten. d,t-malic acid disodium salt trihydrate can be obtained.

The wet d,/,-IJ malate dinato IJ salt trihydrate obtained by the method described above has a moisture content of 23.3%, which does not change when dried at room temperature to 50°C. Estimated to be a hydrate.

In addition, regarding the hydrate of malic acid disodium salt, 1
/ Dihydrate, monohydrate, dihydrate, and tetrahydrate are known (see Official Food Additives Standard, Chemical Encyclopedia), and trihydrate is not known, but its water content is is calculated to be 233%, which is almost the same as the water content when the wet d,t-IJ malate dinatriudinium salt hydrate is dried to a constant weight, so it is treated as a trihydrate. Ta.

The wet d,,ff-IJ malate dinato IJ salt trihydrate obtained by the method as described above usually contains 23 to 81% of water; in this case, the wet d, /, −
IJ malic acid resin sodium salt trihydrate put in dryer 55
After reducing the moisture content to 20% or less at ~60℃, then 70~
Kokichi can be dried at 120° C. without solidifying or semi-melting to the desired moisture content of 15% or less.

If the moisture content of wet d,t-malic acid disodium salt trihydrate is 31% or more, there is a risk of sintering, so please pre-dry it at 50°C or less to reduce the moisture content to 31% or less. The drying method described above can also be used.

The drying temperature in the method of the present invention is 5% to remove the wet d, t-IJ coral acid dinatriudisodium salt trihydrate (water content of 23.3% or more) obtained by the method as described above.
It may be 0°C or lower, but the water content included as hydration water is 23
．． In order to reduce the salinity from 30% to 20%, a salinity of 50°C or higher, especially 55 to 60°C, is required.

It is not suitable for drawing at temperatures above 60°C as there is a risk of it becoming half-melted.

Then, to reduce the moisture content to within 15%, the temperature should be 70 to 120°C.
The drying temperature must be increased to

At temperatures below 70°C, it takes a long time to dry; at temperatures above 120°C, disodium d,t-malate may deteriorate; and especially at temperatures above 180°C, intramolecular condensation and '2° molecular condensation may occur. , the content decreases significantly.

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, "water content" in the specification refers to the percentage of the wet basis of free water and hydrated water, "%" indicates parts by weight unless otherwise specified, and "parts" indicates parts by weight. Some indicate semi-melting.

Note that the water content was measured by the Karl Fischer method.

Example 1 500 parts of an aqueous solution containing 60 parts of disodium d,t-malate is cooled to 80° C. with stirring to allow crystallization.

After 6 hours, centrifuge and moisten. 335 parts of t-malic acid cina) IJium salt hydrate crystals were obtained.

The moisture content of the wet crystals is 28.5%, and when dried at 50°C to a constant weight, the moisture content (estimated to be water of hydration) is 2.
It was 3.3%.

The wet d,7-malic acid disodium salt trihydrate 33
5 parts were placed on a metal pallet to a thickness of 3 crrL, placed in a ventilation box dryer, and kept at 55-60°C for 5 hours.
It was then kept at 80°C for 5 hours.

Loss on drying was 71 parts.

The water content of the obtained d, ff-IJ malic acid resin sodium salt was 9.2%.

Comparative Example Moisture d with a moisture content of 28.5% obtained in Example 1,
7-IJ malic acid dinatriudisodium salt trihydrate 33
5. When placed in a ventilation dryer and maintained at 80°C, the entire crystal solidified into one piece, and the lower part of the pallet took on a candy-like appearance and could no longer be dried.

Claims (1)

[Claims] Wet disodium malate obtained by crystallization and separation under stirring from an aqueous solution containing disodium malate of 150% or higher) IJ
In order to produce malic acid disodium salt hydrate with a water content of 15 or less by drying crystals of malic acid salt hydrate, the crystals with a water content of 23 to 31% (including water of hydration) are dried at 55 to 60°C.
After drying to reduce the moisture content to below 20%, dry at 70-120°C.
A method for drying malic acid cina) IJJum hydrate to a moisture content of 15% or less.