JP3040855B2 - Freezing stabilization method of cellulose aqueous dispersion - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention imparts freeze-resistant stability to a water-soluble cellulose dispersion having a sol or gel structure, which retains a large amount of water, and restores the original stable sol or gel structure after thawing. Related to new technology.

[0002]

2. Description of the Related Art Finely divided cellulose often retains a large amount of water, has a sol or gel structure, and often has a creamy appearance at first glance, has a high function, is a suspension stabilizer of fine particles, a food, and the like. Are used in many fields such as body-imparting agents, texture improvers, emulsion stabilizers, and dietary fiber. This substance contains a large amount of water and is easily rotted.If frozen storage is performed to prevent this, water is separated at the time of thawing and the original sol or gel structure cannot be obtained. However, there is a drawback that the function as a state dispersion is lost, and there is no means for solving this.

[0003]

SUMMARY OF THE INVENTION The present invention enables the preservation of a large amount of water and the storage of a cellulose aqueous dispersion having a sol or gel structure by freezing and preserving a sol or gel structure before freezing even after thawing. The purpose is to reproduce the high functionality of.

[0004]

As a result of investigations to solve the above-mentioned problems, it has been found that by adding a water-soluble alcohol or a water-soluble base upon freezing, water separation during melting can be prevented, and the original sol or gel can be prevented. The inventors have found that the structure can be reproduced and the original function can be maintained, and the present invention has been achieved.

That is, the present invention provides a method for freezing a water dispersion of cellulose having a sol or gel structure while retaining a large amount of water.
A freeze-stabilization method for an aqueous dispersion of cellulose, which comprises adding a water-soluble alcohol or a water-soluble base. For example, an aqueous dispersion of cellulose that holds a large amount of water and has a sol or gel structure is, for example, INDUSTR.
IAL & ENGINEERING CHEMIST
RY VOL. 42 gels of microcrystalline cellulose described in P502-507, for example, JOURNAL
OF POLYMER SCIENCE: PART C
NO. 2 P129-144 (1963), an undried product of monofibrillated cellulose obtained by, for example, applying cellulose fibers to a homogenizer in water and fibrillating with a strong shear, or, for example, a genus Acetobacter or Pseudomonas And undried products of bacterial cellulose which are said to be well produced by microorganisms such as Agrobacterium and undried water of cellulosic fine crystals obtained from the above bacterial cellulose described in, for example, JP-A-61-215635. Dispersions and, for example, JP-A-61-241337
Undried aqueous dispersion of fine cellulose particles composed of regenerated cellulose described in JP-A-3-5877
Among the aqueous paste compositions described in No. 0, such as those mainly composed of cellulose, such as cellulose-based fine particles or fine fibrils, form a kind of hydrated colloid to stably disperse in water or retain water in large amounts It is effective to use an aqueous dispersion having the above properties. What can be said in common among them is that when they are dried alone, hydrogen bonds are formed at the time of drying on the cellulose particles or on the surface, and keratinization occurs. Generally, these cellulose aqueous dispersions are usually handled in a wet state, and the cryopreservation of the above cellulose aqueous dispersion has been attempted, but water cannot be separated at the time of thawing to return to a stable hydrated structure. . The present invention is applicable to all hydrated dispersions of cellulose having the above sol or gel structure. The concentration of these cellulose hydrate dispersions is effective for those having a solid content in the range of about 0.1% by weight to about 80% by weight.

Examples of water-soluble alcohols to be added include low-molecular-weight sugars such as glucose, fructose, xylose, arabinose, sorbose, mannose, sucrose, maltose, glucuronic acid, galacturonic acid, lactose, glucosamine, galactosamine, and ribose invert sugar.
Oligosaccharides such as dextrin which is a hydrolyzate of starch, polyhydric alcohols such as glycerin, ethylene glycol, etc., lower alcohols such as methanol, ethanol, isopropyl alcohol, propanol, octanol, etc., water-soluble polyoxyethylene glycols, Polyols such as water-soluble polyoxypropylene glycols, esters and ethers of water-soluble polyalkylene glycol derivatives and their ether ester derivatives, xanthan gum, karaya gum, carrageenan, pectin, mannan, guar gum, sodium alginate, pullulan, tragacanth gum, Natural water-soluble polysaccharides such as gum arabic,
Sodium carboxymethylcellulose, methylcellulose, hydroxymethylcellulose, hydroxypropylcellulose, hydroxymethylpropylcellulose,
Water-soluble cellulose such as sodium carboxymethyl starch, phosphorylated starch, hydroxyethyl starch, hydroxyethyl guar gum, starch, and other polysaccharide derivatives. The amount of the water-soluble alcohol to be added is required to be at least about 0.05% by weight or more in the aqueous solution component excluding the cellulose component. The upper limit of the addition is not particularly limited, but is determined from a practical viewpoint. In the case of low molecular weight water-soluble alcohols, the upper limit can be used up to about 90% of the total weight of solids including cellulose. In the case of high molecular weight water-soluble alcohols, it is determined by the viscosity of the whole system,
The upper limit is the amount added so that the viscosity of the whole system becomes about 1000 poise. A preferred range is an addition concentration of about 0.1% by weight or more in the aqueous solution component excluding the cellulose component, and the upper limit is 50% of the total solid content weight including cellulose in the case of low molecular weight water-soluble alcohols. Less than or equal. In the case of high molecular weight water-soluble alcohols, it is recommended that the concentration be lower than the concentration at which the viscosity of the whole system becomes about 10 poise.

The water-soluble bases include sodium hydroxide,
A basic compound having a hydroxyl group that can be dissolved and hydrated in water, such as aqueous ammonia, calcium hydroxide, pyridine, and ethanolamine, can be used. Since basic compounds are often accompanied by a structural change of cellulose itself, it cannot be used at a very high concentration, and its use is also limited. The approximate range of use is about 0.001% by weight or more and about 5% by weight as the concentration of the basic compound.
It is as follows. The preferred range is at least 0.01% by weight of the basic compound in the aqueous solution excluding the cellulose component.
% By weight or less.

When adding the water-soluble alcohols or water-soluble bases, it is important that they be uniformly mixed and dispersed in the entire system, but the method of addition is not particularly limited.
Even when added at the same time as making a cellulose aqueous dispersion,
It may be added later. Further, it may be directly added to the aqueous cellulose dispersion, or a master batch may be prepared and added and mixed. In any case, it is necessary to sufficiently stir or shear to uniformly mix. In particular, in the case of high molecular weight water-soluble alcohols, it is desirable to allow sufficient dissolution and dispersion time, and to apply shear or temperature as necessary.

The use of one kind of water-soluble alcohols or water-soluble bases is effective, but water-soluble alcohols or water-soluble bases may be used alone, or water-soluble alcohols and water-soluble bases may be used in combination. 2 out of
A combination of more than one species may be used. In freezing and thawing the aqueous cellulose dispersion to which a water-soluble alcohol or a water-soluble base is added, general freezing and thawing methods can be used freely, and there is no particular limitation.

[0010] After the melting, some water separation may occur, but this can be easily returned to the original complete cellulose aqueous dispersion by applying weak stirring. The present invention relates to a freeze-stabilization method for a cellulose aqueous dispersion, which comprises adding a water-soluble alcohol or a water-soluble base when freezing a cellulose aqueous dispersion having a sol or gel structure while retaining a large amount of water. Things.

[0011]

The present invention will be described in more detail with reference to Examples and Comparative Examples.

[0012]

Example 1 200 g of dissolving pulp for rayon having an average degree of polymerization of about 1200 was placed in 2 liters of 1N sulfuric acid solution and stirred in a glass vessel equipped with a reflux condenser at 98 ° C. for 180 minutes. Decomposed. The hydrolyzate was neutralized with a sodium hydroxide solution, washed with water and filtered to obtain a cake. A small amount of this product was collected and dried, and the average degree of polymerization was measured to be 198. The cake contained 61% water. This operation was repeated for two batches, and a 600 g cake-like product was collected in a water-containing state, placed in a universal stirring mixer manufactured by Shinagawa Seisakusho, and attached with a high-viscosity arm, followed by stirring for 30 minutes. The stirring was stopped about every 6 minutes on the way, and the components adhering to the upper portion were scraped off. After 30 minutes, 400 g of water was gradually added, and stirring was continued for 10 minutes to obtain a white cream-like microcrystalline cellulose gel.

[0013]

Example 2 The microcrystalline cellulose gel of Example 1 was diluted to a concentration of 0.5%, and then centrifuged at 2000 RPM for 15 minutes in a centrifugal sedimentator with a domestically produced rotor having a radius of 800 mm. A liquid was obtained.

[0014]

EXAMPLE 3 20 grams of dissolving pulp for cellulose ether having an average degree of polymerization of about 1540 was put into a household mixer, 800 ml of water was added, and the mixture was stirred at a low speed for about 2 minutes and then at a high speed for 5 minutes to obtain a fiber. A slurry was obtained. This is passed through a Menton-Gaulin homogenizer 2
The mixture was passed 10 times at a pressure of 00 kg / cm 2 to obtain a viscous aqueous monofibrillated cellulose dispersion.

[0015]

Example 4 Acetobacter xylinum was prepared by adding 1% by weight of D-glucose, 1% by weight of peptone, and 0.3% of yeast extract.
% Of sodium chloride, 0.2% by weight of sodium chloride, 0.14% by weight of disodium phosphate, and 0.035% by weight of citric acid at a culture temperature of 28 ° C. and a medium pH of 6.8.
The culture was allowed to stand for 5 days to obtain an aqueous dispersion of konjac-like bacterial cellulose on the surface of the incubator. This konjac-like thick film-form bacterial cellulose was immersed in a 30% by weight sugar solution for one week to replace the water inside the thick film with the sugar solution, put into a freezing room at minus 40 ° C., frozen, then returned to room temperature and thawed. . It was confirmed that the bacterial cellulose returned to the original konjac-like thick film state.

[0016]

Example 5 One kilogram of dissolved pulp for rayon having an average degree of polymerization of 720 was immersed in a 18% by weight sodium hydroxide solution at 20 ° C. for 30 minutes, crushed 2.5 times, and then loosened into cotton to obtain an oxygen concentration of 40%. Put in an atmosphere of 40 ° C. for 10 hours,
Then, 35% by weight of carbon disulfide was added to the cellulose and sulfurized at 25 ° C. for 1 hour to obtain xanthate.
This was dissolved in a sodium hydroxide solution to give a cellulose concentration of 8
By weight, a viscose solution having a sodium hydroxide concentration of 6% by weight was obtained. Take 2 kilograms of this viscose solution, 2
The mixture was solidified by stirring into a 6% by weight sodium sulfate solution and solidified.
Regeneration was carried out with a 10% by weight sulfuric acid solution at RPM agitation. This was filtered and washed 5 times and then made into a regenerated cellulose slurry of about 10% by weight.
Feeding rate: 0.25 liter / min, beads: zirconia, made to pass under the condition of a diameter of 2 millimeters to obtain a creamy aqueous cellulose dispersion.

[0017]

Embodiment 6 Embodiment 1, Embodiment 2, Embodiment 3, Embodiment 5
Was placed in a 300 ml beaker, various compounds were added at various ratios as shown in Table 1, and the mixture was stirred with a lab stirrer at about 500 RPM for 30 minutes. 20 of them
Milliliters were placed in test tubes and placed in a minus 40 ° C. freezer for 2 hours to freeze. After returning to room temperature and allowing to naturally thaw, the state was observed. The results are shown in Table 1.

[0018]

Example 7 (1) Aqueous dispersion of microcrystalline cellulose gel of Example 1 and (2) After adding 5% by weight of sugar to the aqueous dispersion of microcrystalline cellulose gel, the mixture was frozen at minus 20 ° C. and then spontaneously at room temperature. The retort stability of the dressing was examined using the melted aqueous dispersion of returned microcrystalline cellulose gel. The basic formula was 50 parts by weight of vegetable oil, 10 parts by weight of vinegar, 3 parts by weight of salt, 0.2 parts by weight of xanthan gum, 38 parts by weight of water, and the above (1) aqueous dispersion of microcrystalline cellulose gel,
Alternatively, (2) 2 parts by weight of the aqueous dispersion of microcrystalline cellulose gel which was thawed and returned after freezing was added to each to prepare a dressing, which was subjected to retort sterilization at 120 ° C. for 30 minutes, and the stability after 3 days was observed. In both (1) and (2), no emulsion separation was observed, indicating that good stability was imparted.

[0019]

Comparative Example 1 Example 1, Example 2, Example 3, Example 5
Was placed in a 300 ml beaker and stirred with a lab stirrer at about 500 RPM for 30 minutes. Twenty milliliters of the solution was placed in a test tube and placed in a freezer at minus 40 ° C for 2 hours to freeze. After returning to room temperature and allowing to naturally thaw, the state was observed. The results are shown in Table 1.

[0020]

[Table 1]

As is evident from Table 1, the aqueous cellulose dispersion to which the water-soluble alcohols or water-soluble bases are added maintains the stability even after freeze-thawing, whereas the non-added system separates water. It can be seen that the cellulosic material was unable to form an aqueous dispersion due to coagulation and sedimentation.

[0022]

Comparative Example 2 The bacterial cellulose obtained in Example 4 which had been frozen without being immersed in sugar, did not have konjac-like properties after thawing, lost its unique slimy feeling and became sponge-like. did not become. From the results of Example 4 and Comparative Example 2, it can be seen that the freeze-thaw stability of bacterial cellulose was increased by the addition of water-soluble alcohols.

[0023]

Comparative Example 3 The dressing stability was evaluated in exactly the same manner as in Example 7 except that 2% by weight of water was used instead of the aqueous dispersion of microcrystalline cellulose gel (1). went. After 3 days, the dressing was observed to have separated the emulsion and about 20% of the layers had separated.

[0024]

According to the present invention, a cellulose aqueous dispersion to which a water-soluble alcohol or a water-soluble base is added can form a stable cellulose aqueous dispersion even after thawing. In particular, it enables frozen storage of an aqueous dispersion stabilizer of cellulose which is effective as a stabilizer often used in foods.

Claims (1)

(57) [Claims] 1. A method for freezing a water-soluble cellulose dispersion, comprising adding a water-soluble alcohol or a water-soluble base when freezing a water-soluble cellulose dispersion having a sol or gel structure while retaining a large amount of water. Chemical method.