JP2018154595A - Plasmalogen-containing aqueous liquid - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a plasmalogen-containing aqueous solution having excellent storage stability, which can be widely used in health foods, pharmaceuticals, analytical reagents, etc., in which decomposition of plasmalogen, which is extremely poor in the presence of water, is suppressed. Provided The aqueous solution of the present invention contains plasmalogen and polyethylene glycol. The molecular weight of the polyethylene glycol is preferably 3000 to 50000. The aqueous solution of the present invention preferably further contains an antioxidant. It is preferable that the antioxidant is one or more antioxidants selected from EDTAs, ascorbic acid, tocopherols, and catechins. [Selection diagram] None

Description

  The present invention relates to an aqueous liquid containing plasmalogen.

  Plasmalogens, also called 1-alkenylacyl phospholipids, are a type of glycerophospholipid that has an olefinil chain (vinyl ether bond) at the sn-1 position of the glycerol skeleton, an acyl chain at the sn-2 position, and a base at the sn-3 position. It has a bound phosphoric acid. Naturally occurring plasmalogen has a main olefinyl chain having 16 to 18 carbon atoms, and a main acyl chain is a fatty acid having 16 to 22 carbon atoms. The main bases that bind to phosphoric acid are choline and ethanolamine, the plasmalogen in which choline is bound to phosphoric acid is choline-type plasmalogen (hereinafter sometimes referred to as CP), and ethanolamine is bound to phosphoric acid. The bound plasmalogen is called ethanolamine type plasmalogen (hereinafter sometimes referred to as EP). For example, it is known that the ratio of CP is high in mammalian heart and skeletal muscle, and the ratio of EP is high in brain and kidney.

  The vinyl ether bond that plasmalogen has in its structure is extremely susceptible to oxidation, and plasmalogens are preferentially oxidized in vivo to prevent oxidative damage of biological components due to active oxygen and free radicals ( Non-patent document 1). In addition, plasmalogens are said to be related to various diseases related to aging and oxidative stress because they are present in a wide range of in vivo tissues, and are considered for use in the prevention of neurodegenerative diseases and Alzheimer's disease. (Patent Document 1 and Patent Document 2). Furthermore, by utilizing the antioxidant ability of plasmalogen, a method of using plasmalogen as an antioxidant that suppresses peroxidation of lipids in living tissues (Patent Document 3) and supply of highly unsaturated fatty acids with excellent oxidative stability A method (Patent Document 4) used as a composition is disclosed.

  Thus, while the usefulness of plasmalogens is attracting attention, there are still many problems in stably storing plasmalogens. As mentioned above, plasmalogens are susceptible to oxidation of vinyl ether bonds, are unstable in the presence of water, and contain many unstable polyunsaturated fatty acid residues. The content tends to decrease at a stretch. For this reason, plasmalogens have been very difficult to use in health foods that require a certain level of concentration, pharmaceuticals that require accurate concentration control, and analytical reagents used to measure their concentrations. In addition, since plasmalogen has a peculiar unpleasant odor, there is also a problem that the amount of addition must be limited when blended into food and drink.

US Pat. No. 5,759,585 JP 2004-26803 A JP 2003-012520 A JP 2003-003190 A

Experimental Gerontology, 1998, Vol.33, No.5, p.363-369

  Accordingly, an object of the present invention is to provide a plasmalogen having excellent storage stability that can be widely used in health foods, pharmaceuticals, analytical reagents, etc., in which the degradation of plasmalogen, which is extremely unstable in the presence of water, is suppressed. It is to provide an aqueous liquid containing.

As a result of intensive studies, the present inventors have found that the above problem can be solved when polyethylene glycol, particularly polyethylene glycol having a specific molecular weight, is added to an aqueous liquid in which plasmalogen is dispersed in water. .
The present invention has been made based on the above findings, and provides an aqueous liquid containing plasmalogen and polyethylene glycol.

  While the aqueous liquid of the present invention contains a plasmalogen, the degradation of the vinyl ether bond at the sn-1 position is suppressed, and a high residual rate is exhibited even during long-term storage. Therefore, it is excellent in storage stability and can be widely used for health foods, pharmaceuticals, analytical reagents and the like.

Hereinafter, the present invention will be described in detail based on preferred embodiments.
First, the plasmalogen used in the aqueous liquid of the present invention will be described.
Plasmalogen is also referred to as a 1-alkenylacyl phospholipid as described above. Among glycerophospholipids, a glycerol skeleton has a vinyl ether-bonded acyl chain at the sn-1 position and an acyl chain at the sn-2 position. It is a lipid having a phosphate with a base bonded to the sn-3 position.
Naturally occurring plasmalogens have a main olefinin chain (vinyl ether bond) having 16 to 18 carbon atoms, a main acyl chain is a fatty acid having 16 to 22 carbon atoms, and an sn-2 acyl chain is arachidonic acid or docosahexaene. Mainly unsaturated fatty acids such as acids. The main bases that bind to the phosphoric acid are choline and ethanolamine.

As a plasmalogen used for this invention, what was extracted from the natural product can be used, for example.
Examples of natural products from which plasmalogens are extracted and separated include various animals, plants, and microorganisms. In the present invention, the natural product from which plasmalogens are extracted and separated is preferably an animal. Examples of animals from which plasmalogens are extracted and separated include mammals such as cattle and pigs, fish such as bonito, tuna and sardine, shellfish such as scallops, oysters and clams, cephalopods such as octopus and squid, crabs and shrimps And the like, and animal tissues of these animals can be used. The animal tissue that can be used in the present invention may be an animal individual itself, muscle tissue, fat tissue, nerve tissue such as brain, visceral tissue such as intestine, and egg thereof. It is preferable to use a bovine or porcine heart or brain from the viewpoint of the content of the rogen or the availability and price.

In the aqueous liquid of the present invention, plasmalogens may be contained in the form of plasmalogen-containing lipids extracted from these various animals, plants, and microorganisms by solvent extraction or the like. The plasmalogen-containing lipid may be contained in the form of a plasmalogen-containing lipid concentrate obtained by subjecting the plasmalogen-containing lipid to liquid-liquid extraction, column chromatography, enzyme treatment, etc. to concentrate and purify the plasmalogen. Furthermore, the plasmalogen-containing lipid concentrate may be contained in the form of a plasmalogen that has been further concentrated and purified. Further, the plasmalogen-containing lipid may be contained in the form of a lipid that has been subjected to processing such as conversion of the fatty acid ester composition or modification of the base moiety.
In the present invention, the plasmalogen-containing lipid and the plasmalogen-containing lipid concentrate mean a lipid having a plasmalogen content of 0.1 to 99% by mass, although it varies depending on the raw material. Plasmalogen content in plasmalogen-containing lipids and plasmalogen-containing lipid concentrates can be determined by, for example, absorption detection by iodine addition (ELGottfried, J. Biol. Chem., 237, 329 (1962)), p-nitrophenyl Hydrazine method (C. Pries, Biochim. Biophys. Acta, 38, 340 (1960)), HPLC analysis method (S. Mawatari, Anal. Biochem., 370, 54 (2007)), LC-MS analysis method (KA Zemski J. Am. Soc. Mass Spectrom, 15, 149 (2004)).

  As methods for extracting plasmalogen-containing lipids from animals and their tissues, Folch method (Folch et al .: J. Biol. Chem., 226, 497-505, 1957), Bligh & Dyer method (Bligh et al .: Can. J. Biochem. Physiol., 37, 911-917, 1959), or a method using a mixed solvent using hexane or lower alcohol, which is a highly safe organic solvent (Hara et al .: Anal. Biochem., 90 (1): 420-6, 1978, JP-A-2005-179340). Moreover, in order to improve extraction efficiency, what dehydrated the said animal tissue can be used. It is preferable to extract using the mixed solvent of hexane and ethanol from the point of safety | security and operativity.

  The plasmalogen-containing lipid concentrate can be obtained from the plasmalogen-containing lipid by the acetone precipitation method (supervised by Tamio Yamakawa: Biochemistry Experiment Course 3, Lipid Chemistry (Edited by the Japanese Biochemical Society), p.19-20. , 1963, Tokyo Chemical Co., Ltd.), column chromatography (James et al .: Lipids, 23, 1146-1149, 1988) and other methods for removing triglycerides can be used, or mammalian pancreatic lipase or microorganisms Diacyl by treatment with phospholipase A1 (Woelk et al .: Z Physiol. Chem. 354, 1265-70, 1973) and weak alkali treatment (Hanahan et al .: J. Biol. Chem. 236, 59-60, 1961) A method of degrading type phospholipids can be used.

The most efficient method for obtaining a plasmalogen-containing lipid concentrate is to react the plasmalogen-containing lipid with phospholipase A1 derived from Actinomadura sp. In a weakly acidic buffer, and re-extract the product with a hexane / ethanol mixed solvent. And a method of obtaining a plasmalogen-containing lipid concentrate by column chromatography using a carrier such as silica gel.
For example, phospholipase A1 (Mitsubishi Chemical Foods) is used, and 0.1 g to 2.0 U of enzyme and 1 to 20% of acetate buffer pH 4.0 to 6.0 are added to 1 g of a mixed lipid of diacyl phospholipid and plasmalogen, preferably Is added at 5-10% and reacted at 30-60 ° C. for 2-100 hours with stirring. Mixing the reaction solution with a mixed solvent of hexane / ethanol / water, for example, hexane 65-90, ethanol 5-20, water 4-10, preferably hexane 75-85, ethanol 8-16, water 8-16 The solvent is added, and the upper hexane layer is collected to recover the plasmalogen-containing lipid concentrate. By this extraction treatment, 1-lysophospholipid generated by the phospholipase A1 reaction can be fractionated to dissolve in the aqueous layer.
The obtained plasmalogen-containing lipid concentrate can be further concentrated by fractionating neutral lipids by acetone precipitation or column chromatography.

  The obtained plasmalogen-containing lipid can be further recovered by the silica gel chromatography which can be concentrated by base composition. For example, plasmalogen-containing lipid is packed in a column packed with silica gel with a mixed solvent of hexane / ethanol, preferably 95: 5 to 60:40, and the solvent is passed through 2 to 8 times the column volume. After the neutral lipid is eluted, the hexane / ethanol mixed solvent, preferably 5:95 to 0: 100, or the ethanol / water mixed solvent, preferably 100: 0 to 95: 5, is added to the column volume of 6-15. By passing a double amount, ethanolamine-type plasmalogen-containing lipid can be fractionated, followed by ethanol / water mixed solvent, preferably 90:10 to 70:30, 8 to 20 times the column volume. By allowing the liquid to pass through in an amount, a choline-type plasmalogen-containing lipid can be fractionated.

  The plasmalogen content in the aqueous liquid of the present invention is preferably 0.0001 to 5% by mass, more preferably 0.001 to 3% by mass, still more preferably 0.002 to 1% by mass, and most preferably 0.001. 003 to 0.3% by mass. If the content of plasmalogen is less than 0.0001% by mass, there is a problem that the functional effect is poor when applied to foods and pharmaceuticals. If it exceeds 5% by mass, an unpleasant odor peculiar to plasmalogen can be felt. There is sex. Conventionally, when plasmalogen is present at a high concentration (for example, 5% by mass), the degradation may occur. However, according to the present invention, the degradation can be effectively achieved by allowing plasmalogen to coexist with polyethylene glycol. Is prevented. In the aqueous liquid of the present invention, when the plasmalogen is contained in the form of a plasmalogen-containing lipid or a plasmalogen-containing lipid concentrate, the plasmalogen-containing lipid or the plasmalogen-containing lipid concentrate is contained in the aqueous liquid. It is preferable to make it contain so that quantity may become the above-mentioned range. The plasmalogen content in the aqueous liquid of the present invention is determined by absorption detection by iodine addition (ELGottfried, J. Biol. Chem., 237, 329 (1962)), p-nitrophenylhydrazine method (C. Pries, Biochim. Biophys. Acta, 38, 340 (1960)), HPLC analysis (S. Mawatari, Anal. Biochem., 370, 54 (2007)), LC-MS analysis (KA Zemski, J. Am. Soc. Mass Spectrom , 15, 149 (2004)).

  The aqueous liquid of this invention can contain fats and oils. In the case of using the plasmalogen-containing lipid or the plasmalogen-containing lipid concentrate in an aqueous liquid for an embodiment containing an oil or fat, for example, the plasmalogen-containing lipid or the plasmalogen-containing lipid concentrate is converted into the following method. When the aqueous liquid of the present invention is produced, it is possible to disperse it as an oil phase as it is, but for the purpose of reducing the oil phase viscosity, a low melting point oil or fat is added, or an oil with high oxidation stability is added It is preferable to distribute. An aqueous liquid excellent in oxidation stability can be obtained by adding fats and oils having high oxidation stability.

The fat to be distributed is not particularly limited, but for example, palm oil, palm kernel oil, palm oil, corn oil, cottonseed oil, soybean oil, rapeseed oil, rice oil, sunflower oil, safflower oil, beef fat, milk fat, pork fat, Examples include vegetable oils and fats such as cocoa butter, fish oil and whale oil, animal fats and oils and processed oils and fats that have been subjected to one or more treatments selected from hydrogenation, fractionation and transesterification. In the present invention, these fats and oils can be used alone or in combination of two or more.
In the present invention, when the oil-in-water emulsion is used as the aqueous liquid, the viscosity becomes easy to produce, and the oil and fat to be added is an oil-in-water emulsion having excellent emulsification stability and oxidation stability. It is preferred to use fractionated soft part oil and / or transesterified oil of palm oil fractionated soft part oil.

  The “aqueous liquid” as used in the present invention includes an oil-in-water emulsion in which an oil-soluble component is dispersed mainly in an aqueous phase in addition to an aqueous solution. In the aqueous liquid of the present invention, the proportion of the aqueous phase is preferably 80% by mass or more, and more preferably 90% by mass.

Subsequently, polyethylene glycol used in the aqueous liquid of the present invention will be described.
When the aqueous liquid of the present invention contains polyethylene glycol together with the plasmalogen, the decomposition of the plasmalogen is suppressed and the storage stability is excellent. In particular, even when the plasmalogen content is as high as 5% by mass, for example, the degradation of plasmalogen is suppressed. The polyethylene glycol that can be used in the present invention is not particularly limited, but it is preferable to use polyethylene glycol having a weight average molecular weight of 3000 to 50000, more preferably weight in terms of extremely high effect of preventing the degradation of plasmalogen. Polyethylene glycol having an average molecular weight of 15,000 to 40,000 is used. When polyethylene glycol having a weight average molecular weight of less than 3000 is used, the effect of preventing the degradation of plasmalogen is low, and polyethylene glycol having a weight average molecular weight of more than 50000 has low solubility in water, making it difficult to produce an aqueous liquid. When the solution is stored for a long period of time, plasmalogens are easily separated, and in this case, the oxidative stability tends to deteriorate. The weight average molecular weight of polyethylene glycol contained in the aqueous liquid of the present invention can be measured, for example, by preparing a calibration curve using polyethylene glycol as a standard substance by gel permeation chromatography (GPC).

  The content of polyethylene glycol in the aqueous liquid of the present invention is preferably 0.1 to 30% by mass, more preferably 0.2 to 10% by mass, and still more preferably 0.3 to 3% by mass. The content of polyethylene glycol can be measured by a known method.

The aqueous liquid of the present invention preferably contains an antioxidant. Examples of the antioxidant include EDTAs (for example, EDTA, disodium EDTA, etc.), ascorbic acid, tocopherol (α, β, γ, or δ tocopherol, or α, β, γ, and δ tocopherol. Examples include mixed tocopherols including the above, catechins, erythorbates, tannins, anthocyanins, polyphenols such as tea polyphenols, L-ascorbic acid stearate, sodium L-ascorbate, and the like. Species or two or more can be used. In the present invention, the antioxidant is preferably one or more antioxidants selected from EDTAs, ascorbic acid, tocopherol, and catechin, more preferably EDTAs, ascorbic acid, The antioxidant which used together 1 type, or 2 or more types selected from tocopherol and catechin is used.
The content of the antioxidant in the aqueous liquid of the present invention is preferably 0.00001 to 5% by mass, more preferably 0.0001 to 0.1% by mass, and still more preferably, although it depends on the type of antioxidant. 0.01 to 1% by mass. In particular, the content of EDTAs is preferably 0.0001 to 1% by mass, more preferably 0.001 to 0.5% by mass, and still more preferably 0.01 to 0.2% by mass.
Moreover, as content of tocopherol, 0.00001-1 mass% is preferable, and 0.0001-0.1 mass% is more preferable. By making it contain in the said range, the effect of this invention can be improved more. The content of the antioxidant can be measured by a known method.

  The aqueous liquid of the present invention contains water. The water used for the aqueous liquid of the present invention may be tap water or mineral water. Moreover, the food raw material containing water, such as milk and fruit juice, can also be used.

In addition, the aqueous liquid of this invention can contain other components other than the said plasmalogen, polyethyleneglycol, fats and oils, and antioxidant. Examples of the other components include complex lipids other than plasmalogen, glycerin fatty acid ester, sucrose fatty acid ester, sorbitan fatty acid ester, propylene glycol fatty acid ester, glycerin organic acid fatty acid ester, polyglycerin fatty acid ester, calcium stearoyl lactate, sodium stearoyl lactate Emulsifiers such as polyoxyethylene sorbitan fatty acid esters, partial glycerides, dairy products, egg products, cacao and cacao products, coffee and coffee products, salting agents such as salt and potassium chloride, acidulants such as acetic acid, lactic acid and gluconic acid, Sugars, sugar alcohols, sweeteners such as stevia and aspartame, colorants such as beta carotene, caramel, and red potato pigments, flavoring agents, pH adjusters, food preservatives, sodium carbonate, propylene glycol, calci Arm salts, phosphates, quality stabilizers iron, and the like, can include food materials and food additives such as shelf life improvers. It is also possible to contain functional materials such as various vitamins, coenzyme Q, plant sterol, plant sterol fatty acid ester, milk fat globule membrane.
The content of the other components in the aqueous liquid of the present invention is not particularly limited, but it is preferably blended so that the total amount is 10% by mass or less, and more preferably 5% by mass or less. Is preferred.

In addition, it does not restrict | limit especially about the manufacturing method of the aqueous liquid of this invention, For example, a plasmalogen can be obtained by emulsifying or disperse | distributing to the water which melt | dissolved polyethyleneglycol. At this time, the plasmalogen is preferably contained in the form of liposomes or micelles. Liposomes are bilayers and micelles are monolayers, but are vesicles with hydrophilic groups facing outward. In order to make the said plasmalogen into the form of a liposome or a micelle, it can obtain easily by adding fats and oils to a plasmalogen as needed, and emulsifying in the water which melt | dissolved polyethyleneglycol.
In addition, what is necessary is just to design a particle size and particle size distribution suitably according to a use.
The aqueous liquid of the present invention thus obtained can be widely used as it is for health foods, pharmaceuticals, analytical reagents and the like.

  EXAMPLES The present invention will be described in more detail with reference to examples below, but the present invention is not limited to these examples. Unless otherwise specified, the molecular weight represents the weight average molecular weight (Mw).

[Production Example 1] Production of plasmalogen-containing lipid A muscle portion of 6 kg (water content 80% by mass) was cut out from a bovine heart, and mixed with hexane: ethanol = 60: 40 into tissue pasted using a homogenizer. 18 L of mixed solvent was added and stirred for 10 minutes. Thereafter, the hexane layer, which is the upper layer of the filtrate obtained by suction filtration, was recovered as a lipid extract. Subsequently, the filtrate lower layer and the filtration residue were combined, 10 L of hexane was newly added thereto, and the mixture was stirred for 10 minutes to extract the lipid fraction, and then the extract was recovered in the same manner as described above. Further, the same operation was repeated once more for the filtrate lower layer and the filtration residue, and the collected extracts were combined for a total of 3 times, and the mixed solvent was removed using an evaporator to obtain 181 g of plasmalogen-containing lipid as a residue. . The resulting plasmalogen-containing lipid had a total phospholipid content of 98% by mass and contained 24% by mass of plasmalogen.

[Examples 1 to 5, Comparative Example 1]
When 0.15 mg of the plasmalogen-containing lipid is dispersed in 10 ml of 0.2 M glycine-NaOH buffer (pH 7.4), a polyethylene glycol having a molecular weight of 400 [PEG-400 / Mw approx. 400, made by ADEKA] (Example 1), polyethylene glycol having a molecular weight of 4,000 [PEG-4000 / Mw approximately 4000, made by ADEKA] (Example 2), polyethylene glycol having a molecular weight of 8,000 [PEG-8000 / Mw about 8000, manufactured by Wako Pure Chemical Industries, Ltd.] (Example 3), polyethylene glycol having a molecular weight of 20,000 [PEG-20000 / Mw about 20000, manufactured by Wako Pure Chemical Industries, Ltd.] (Example 4), molecular weight 35,000 Polyethylene glycol [PEG-35000 / Mw approximately 28000, manufactured by Merck & Co., Ltd.] 5) pre respectively was used after dissolving 140 mg. Further, a dispersion in which 0.15 mg of the plasmalogen-containing lipid was dispersed in 10 ml of the above-mentioned buffer solution without addition of polyethylene glycol was also prepared (Comparative Example 1). The plasmalogen content in the aqueous liquids of Examples 1 to 5 was 0.00036% by mass, and the polyethylene glycol content was 1.4% by mass.

The stability of plasmalogens in the aqueous liquids of Examples 1 to 5 and Comparative Example 1 was evaluated as follows.
As a method for evaluating the stability of plasmalogen, 300 μl of each sample was taken into a 10 ml test tube, water-soluble radical initiator (AAPH) was added to 50 mM, and then incubated at 37 ° C. for 2 hours, and lipid was obtained by a conventional method. The plasmalogen content was measured using HPLC, and the residual rate relative to the plasmalogen content of the sample before the stability test was evaluated.

  The evaluation results are shown in Table 1. In Comparative Example 1 using a buffer solution not containing polyethylene glycol, the residual rate of plasmalogen was only 8%, while in Examples 1 to 5 in which polyethylene glycol was added, the residual rate of plasmalogen Was as high as 56 to 93%. In particular, the effects of the aqueous liquids of Examples 2 to 5 containing polyethylene glycol having a molecular weight of 3,000 to 50,000 are high, and further Examples 4 and 5 containing polyethylene glycol having a molecular weight of 15,000 to 40,000 and It can be seen that the effect of the aqueous liquid No. 5 is higher.

[Examples 6-9, Comparative Examples 2-3]
Disperse 2.16 mg of the plasmalogen-containing lipid in 10 ml of 0.2 M glycine-NaOH buffer (pH 7.4) dissolved in 50 mg of polyethylene glycol having a molecular weight of 20,000 and 0.3 mg / ml of EDTA as an antioxidant. An aqueous liquid was prepared (Example 6). Further, an aqueous liquid was prepared in the same manner as in Example 6 except that 1.8 μg / ml of mixed tocopherol was used instead of EDTA as an antioxidant (Example 7). Further, an aqueous liquid was prepared in the same manner as in Example 6 except that it was dissolved in an amount of 1.8 μg / ml mixed tocopherol in addition to EDTA (Example 8). Furthermore, an aqueous liquid was prepared in the same manner as in Example 6 except that the antioxidant was not added (Example 9).
The plasmalogen content in the aqueous liquids of Examples 6 to 9 was 0.0052% by mass, and the polyethylene glycol content was 0.5% by mass.
Meanwhile, 2.16 mg of the plasmalogen-containing lipid was dispersed in 10 ml of 0.2 M glycine-NaOH buffer (pH 7.4) to prepare an aqueous solution (polyethylene glycol and antioxidants were not added, Comparative Example 2). . Further, an aqueous liquid was prepared in the same manner as in Comparative Example 2 except that a buffer solution dissolved to 0.3 mg / ml EDTA was used as an antioxidant (Comparative Example 3).

As a method for evaluating the stability of plasmalogen, put 1.5 ml of each sample into a 3 ml crimp vial and leave it in a thermostatic bath at 25 ° C. in the dark, on the 0th, 5th, 12th and 20th days. On the 33rd and 47th days, lipids were extracted by a conventional method, the plasmalogen content was measured using HPLC, and the residual rate relative to the plasmalogen content of the sample before the stability test was evaluated.
The evaluation results are shown in Table 2. From Table 2, it can be seen that the aqueous liquids of Examples 6 to 9 have an increased residual rate of plasmalogen compared to the aqueous liquids of Comparative Examples 2 and 3. Moreover, it turns out that the residual rate of a plasmalogen has increased the aqueous liquid of Examples 6-8 containing antioxidant compared with the aqueous liquid of Example 9 which does not contain antioxidant. In particular, it can be seen that the residual ratio of the aqueous liquid of Example 8 using EDTA and tocopherol is particularly excellent.

Claims (4)

  An aqueous liquid containing plasmalogen and polyethylene glycol.   The aqueous liquid according to claim 1, wherein the polyethylene glycol has a molecular weight of 3000 to 50000.   Furthermore, the aqueous liquid of Claim 1 or 2 containing antioxidant.   The aqueous liquid according to claim 3, wherein the antioxidant is one or more antioxidants selected from EDTAs, ascorbic acid, and tocopherol.