JPH0768284B2 - Method for removing residual water-friendly organic solvent in solid polysaccharides - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial field of application> Water-soluble natural polysaccharides are used in a wide range of fields such as food and industry due to their properties. The present invention provides a method for removing a water-affinitive organic solvent in a solid polysaccharide in a drying step of a water-soluble natural polysaccharide.

<Prior Art> As a method for obtaining a purified product from an aqueous solution from which impurities of a water-soluble natural polysaccharide are removed, a gel press method, a drum dry method, a dehydration method using a water-affinitive organic solvent, etc. are known, but other methods are known. It is said that the dehydration method using a water-affinitive organic solvent is preferable because it is easier to obtain a highly purified product as compared with.

Conventionally, when purified products using a dehydration method with a water-affinitive organic solvent are used in the food field, there is concern that the residual water-affinitive organic solvent may affect the taste, the odor, or the human body. For this reason, it is preferable that the water-affinitive organic solvent does not remain as much as possible. Therefore, from the initial stage of drying, air having a temperature of 50 to 90 ° C. and a humidity of 5% RH or less that can maintain the desired quality of the refined product is blown, the product is dried to a desired solid content, and the product is pulverized to obtain a purified product.

<Problems to be Solved by the Invention> However, in the method for removing the water-affinitive organic solvent by the conventional drying method as described above, since the evaporation rate of water and the water-affinitive organic solvent is high, The rate of migration from the inside of the polysaccharide to the surface becomes slower than the evaporation rate on the surface, and the surface hardening of the solid polysaccharide is induced before the inside dries, and the surface becomes dense. Diffusion is suppressed and remains inside even after drying for a long time. Therefore, the removal of the water-affinitive organic solvent is not sufficient and about 500 to several thousand ppm remains in the purified product.

Therefore, a more effective method for removing the residual water-affinitive organic solvent in the solid polysaccharide has been demanded.

<Means for Solving the Problems> In view of the above situation, the present inventors have earnestly studied the method for removing the residual water-affinitive organic solvent in the solid polysaccharide, and as a result, arrived at the present invention.

That is, the gist of the present invention is in the purification of water-soluble natural polysaccharides, a solid polysaccharide obtained by adding a water-affinitive organic solvent to an aqueous solution of the polysaccharide and collecting the precipitate by air with a humidity of 70 to 95% RH. It is a method for removing the residual water-affinitive organic solvent in the solid polysaccharide, which is characterized by treatment.

Aqueous solutions of water-soluble natural polysaccharides include alginic acid, carrageenan, fucereran, pectin, tamarind gum,
Guar gum, xanthan gum, locust bean gum,
An example is a liquid obtained by passing an extraction liquid extracted from a raw material such as tara gum by various methods.

To deposit a precipitate from these aqueous solutions, an appropriate amount of a water-affinitive organic solvent is added. As the water-affinitive organic solvent, alcohols such as methyl alcohol, ethyl alcohol and isopropyl alcohol, ketones such as acetone, ethers such as tetrahydrofuran and dioxane can be used.

Examples of solid-liquid separation of the precipitate include a method using a centrifuge, a vibrating screener and the like.

In this way, solid-liquid separation is performed and the water-affinity organic solvent is 20-50%.
The solid polysaccharide in which (w / w) remains is then supplied to a dryer for humidification treatment for removing the residual water-affinitive organic solvent.

As the dryer, any type may be used as long as it is a ventilation dryer, and either fixed bed type or fluidized bed type may be adopted.

As a method of managing the air humidity and temperature for humidification treatment,
A method of controlling the entire air in the room where the dryer is installed, a method of controlling the air at the air intake side of the dryer body, and the like can be exemplified, and any method may be adopted.

As the air humidity for humidification treatment, if it is less than 70% RH, the migration rate of the water-affinitive organic solvent from the inside of the solid polysaccharide to the surface becomes slower than the evaporation rate on the surface, and the surface hardening of the solid polysaccharide does not occur. Even if it is generated and dried for a long time, it is difficult to reduce the water-affinity organic solvent, which is not preferable. When it exceeds 95% RH, it is a solid substance of water-soluble natural polysaccharides, so the surface is dissolved by moisture in the air and the solid polysaccharides are fused to each other, making it impossible to sufficiently remove the water-affinitive organic solvent inside the solid polysaccharides. Not preferred because of From these, the air humidity for humidification is 70% RH to 95%
RH is suitable.

If the air temperature for the humidification treatment exceeds 50 ° C., the solid polysaccharide is likely to dissolve on the surface due to heat, and the water-affinitive organic solvent in the solid polysaccharide tends to be difficult to remove, which is not preferable. When the temperature is lower than 1 ° C, moisture in the air is frozen and humidification becomes difficult, which is not preferable. From these, the air temperature for the humidification treatment is preferably 1 ° C to 50 ° C.

As the air flow rate for humidification treatment, even if the treatment exceeds 50 m ³ / min ・ m ² , the rate of movement of the water-affinitive organic solvent from the solid polysaccharide to the surface becomes the rate-determining factor. The removal efficiency of the solvent is not improved, the energy loss is large and the economical efficiency is deteriorated, so that it is preferably 50 m ³ / min · m ² or less, more preferably 1 to ³⁰ m ³ / min · m ² .

As for the shape of the solid polysaccharide to be humidified, if the volume of one lump is too large, it takes a long time for the humidification treatment, so the volume of one lump is preferably 20 cm ³ or less, and the granular and finer ones are more preferable. preferable.

Regarding the time for humidifying treatment, the charged amount of solid polysaccharide,
Since the necessary time changes depending on the air volume and the like, it may be determined in advance by grasping the changes over time of the charged amount and the residual water-affinitive organic solvent, and taking into consideration productivity, economic efficiency, and the like.

After the residual water-affinitive organic solvent in the solid polysaccharide is removed by the treatment as described above, hot air is blown in to remove the remaining water. As the hot air, air having a temperature of 50 ° C. to 90 ° C. and a humidity of 5% RH or less at which the quality of the target purified product can be maintained is used. Regarding the air volume, if it is too large, surface hardening may occur early and uniform water removal may not be possible, but such polysaccharides are usually dissolved in water or added with water before use. Therefore, unlike the organic solvent, even if water remains, it does not affect the quality and does not cause much trouble, so it may be appropriately determined. The time for feeding hot air may be controlled so as to reach the target moisture content in consideration of the amount of solid polysaccharide charged, the amount of air, and the like.

The dried product thus obtained can be crushed and adjusted to an appropriate particle size to be a purified product.

<Examples> The present invention will be specifically described below with reference to Examples.

In addition, the quantitative determination of the residual amount of the water-affinitive organic solvent in the purified products in Examples and Comparative Examples was carried out by a gas chromatography method.

Example 1 Roughly-purified locust bean gum (trade name: polygum) 3.5k
g and 50 g of calcium chloride were dispersed in 300 liters of water, dissolved by stirring at 85 ° C. for 1 hour, 3.7 kg of a per-auxiliary agent was added and mixed, and the mixture was pressurized with a filter press. Next, the same volume of 87% (w / w) isopropyl alcohol (IPA) was added to the solution to cause precipitation, and solid-liquid separation was performed with a centrifuge, solid content 30.0% (w / w), water content 42.5%. (W / w), IPA 27.5% (w
/ w) 8.3 kg of dehydrated precipitate having a volume of 20 cm ³ or less was obtained. Next, this dehydrated precipitate was subjected to a ^first drying using a fluidized bed ventilation dryer (FA-75 manufactured by Hosokawa Micron, drying plate area 0.28 m ² ).
Humidification treatment is performed for 2 hours under the conditions shown in the table, and then 80 ℃,
Drying with hot air of 50m ³ / min ・ m ² for 1 hour, crushing 2.5kg
To obtain purified locust bean gum. The amount of residual IPA in this purified locust bean gum was low as shown in Table 1.

Comparative Example 1 8.3 kg of dehydrated precipitate of locust bean gum obtained in the same manner as in Example 1 was subjected to no humidification treatment at 80 ° C., 50 m ³ / min.
Hot air drying of m ² was carried out for 3 hours, followed by pulverization to obtain 2.5 kg of purified locust bean gum. As shown in Table 1, the amount of residual IPA in this purified locust bean gum was clearly higher than that in Example 1.

Comparative Example 2 8.3 kg of dehydrated precipitate of locust bean gum obtained in the same manner as in Example 1 was subjected to a humidification treatment for 2 hours under the conditions shown in Table 1, and then hot air of 80 ° C. and 50 m ³ / min · m ² . It was dried for 1 hour and pulverized to obtain 2.5 kg of purified locust bean gum. As shown in Table 1, the residual IPA in this purified locust bean gum was clearly higher than that in Example 1.

Example 2 Alkali-treated Yukiuma Kotoni from Filipin
After 4.2 kg was washed with water, 3.0 kg of diatomaceous earth and 200 g of sodium hexametaphosphate were added, and extraction was performed for 2 hours in 300 l of warm water at 85 ° C. The pH of the extract was adjusted to 8.0 to 9.5 with hydrochloric acid or potassium hydroxide, and then pressurized with a filter press.
Next, 87% (w / w) IPM of twice the volume (v / v) was added to the solution to precipitate, and a centrifuge was used to perform solid-liquid separation and solid content.
30.0% (w / w), moisture 32.0% (w / w), IPA content 38.0% (w /
w) 8.3 kg of dehydrated precipitate having a volume of 20 cm ³ or less was obtained. Next, using the same dryer as in Example 1, humidification treatment was performed for 2 hours under the conditions shown in Table 2, and then 80 ° C., 50 m ³ / min · m.
Hot air drying of ² was carried out for 1 hour and crushed to obtain 2.5 kg of purified carrageenan. The amount of residual IPA in this purified carrageenan was low as shown in Table 2.

Comparative Example 3 8.3 kg of the dehydrated precipitate of carrageenan obtained in the same manner as in Example 2 was subjected to hot air drying at 80 ° C. and 50 m ³ / min · m ² for 3 hours without being humidified, and crushed to give 2.5 kg. Obtained purified carrageenan. The amount of residual IPA in this purified carrageenan is second
As shown in the table, a large amount remained as compared with Example 2.

Comparative Example 4 8.3 kg of a dehydrated precipitate of carrageenan obtained in the same manner as in Example 2 was subjected to a humidification treatment for 2 hours under the conditions shown in Table 2 and then dried with hot air at 80 ° C. and 50 m ³ / min · m ^2. The mixture was crushed for 3 hours to obtain 2.5 kg of purified carrageenan. As shown in Table 2, the amount of residual IPA in this purified carrageenan was clearly higher than that in Example 2.

Example 3 Crude purified xanthan gum (Jung industrial grade) 4.
1 kg was dispersed in 400 l of water, dissolved by stirring at 80 ° C. for 1 hour, 6.0 kg of perlite as a super-auxiliary agent was added and mixed, and the mixture was pressurized with a filter press. Next, 1% (w /
v) potassium chloride of 2.5 times the amount (v / v) of 87
% (W / w) IPA is added to form a precipitate, which is subjected to solid-liquid separation by a centrifuge, solid content 40.0% (w / w), water content 25.0% (w / w).
w), IPA content 35.0% (w / w), 8.3 kg of dehydrated precipitate having a volume of 20 cm ³ or less was obtained. Next, using the same dryer as in Example 1, a humidification treatment was carried out for 2 hours under the conditions shown in Table 3, followed by hot air drying at 80 ° C. and 50 m ³ / min · m ² for 1 hour, and crushing to 3.3 kg. To obtain purified xanthan gum. The amount of residual IPA in this purified xanthan gum was low as shown in Table 3.

Comparative Example 5 8.3 kg of dehydrated precipitate of xanthan gum obtained in the same manner as in Example 3 was subjected to hot air drying at 80 ° C. and 50 m ³ / min · m ² for 3 hours without being humidified, and pulverized to obtain 3.3 kg of purified xanthan gum. Got The residual IPA in this purified xanthan gum is the third
As shown in the table, a large amount remained as compared with Example 3.

Comparative Example 6 8.3 kg of dehydrated precipitate of xanthan gum obtained in the same manner as in Example 3 was subjected to humidification treatment for 2 hours under the conditions shown in Table 3, and then dried with hot air at 80 ° C. and 50 m ³ / min · m ^2. The mixture was crushed for 1 hour to obtain 3.3 kg of purified xanthan gum. As shown in Table 3, the amount of residual IPA of this purified xanthan gum was clearly higher than that of Example 3.

<Effects of the Invention> As described above, according to the method of the present invention, the concentration of the residual water-affinity organic solvent is increased by the method of obtaining a highly pure product by using the water-affinity organic solvent for the recovery of the polysaccharide aqueous solution. It has a feature that it can be reduced to a width.

Claims (1)

[Claims] 1. When purifying a water-soluble natural polysaccharide, a solid polysaccharide obtained by adding a water-affinitive organic solvent to an aqueous solution of the polysaccharide and recovering the precipitate is treated with air having a humidity of 70 to 95% RH. A method for removing a residual water-affinitive organic solvent in a solid polysaccharide, comprising: