Modified glucomannan

Abstract

To provide a modified glucomannan with novel properties, exhibiting enhanced viscosity expression.SOLUTION: The present invention provides a modified glucomannan, which is a modified product of glucomannan. Defining the weight average molecular weight of the modified glucomannan as M1 and defining the viscosity of a 1 mass% aqueous solution of the modified glucomannan at 25°C as V(mPa s), M1 and V satisfy the conditions of formula (A1), formula (A2) and formula (A3).SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to modified glucomannans. [Background technology]

[0002] Modified thickening polysaccharides obtained by modifying thickening polysaccharides are being considered for use as various food materials such as thickeners, gelling agents, and stabilizers. One method for modifying thickening polysaccharides is to modify them by cutting the polysaccharide molecules. For example, Patent Document 1 describes a method for producing low-strength agar in which the jelly strength is adjusted to a predetermined range by cutting the molecules of the agar component into short pieces. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 5-317008 Summary of the Invention [Problem to be solved by the invention]

[0004] Glucomannan, a type of thickening polysaccharide, is a polysaccharide in which D-glucose and D-mannose are linked by β-1,4 bonds in a molar ratio of about 1:1.6. A modified glucomannan (modified glucomannan) can be obtained by cutting the main chain of this glucomannan in a specific manner and reducing the molecular weight of the glucomannan. The water solubility of such modified glucomannan is improved by reducing the molecular weight, and it can be used as a thickening agent with high handleability.

[0005] On the other hand, depending on the method for modifying glucomannan, even though the glucomannan is reduced in molecular weight, the viscosity when dissolved in water does not increase sufficiently, and the desired viscosity expression may not be obtained.

[0006] An object of the present invention is to provide a modified glucomannan having excellent viscosity expression and novel properties. [Means for solving the problem]

[0007] The present inventors have discovered that, depending on the method of modifying glucomannan, when the main chain of glucomannan is cut to reduce the molecular weight, the acetyl group present as the side chain of glucomannan may be cut (deacetylated). Deacetylation of glucomannan strengthens hydrogen bonds between molecules, reduces the water solubility of the modified glucomannan, and reduces the viscosity expression. That is, the main chain of glucomannan is cut with deacetylation, and the resulting modified glucomannan has two contradictory phenomena: "increase in water solubility due to reduction in molecular weight" and "decrease in water solubility due to deacetylation". As a result, in such modified glucomannan, it is presumed that the viscosity at the time of dissolution is not correlated despite the glucomannan being reduced in molecular weight, and the desired viscosity expression cannot be obtained.

[0008] In view of the above, the present inventors have found a method for modifying glucomannan that can reduce the molecular weight of glucomannan while suppressing deacetylation. As a result, modified glucomannan having properties that have not existed in the past can be obtained, and such modified glucomannan has excellent viscosity expression, and thus the present invention has been completed.

[0009] In one aspect, the present invention relates to the following invention. [1] A modified glucomannan, which is a modified product of glucomannan, The weight average molecular weight of the modified glucomannan is M 1 and the viscosity of a 1% by mass aqueous solution of the modified glucomannan at 25°C is V (mPa s), M 1 and V satisfies the conditions of the following formula (A1), the following formula (A2), and the following formula (A3).

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[0010] In other aspects, the present invention also relates to the following inventions. [1-1] The recovery rate in the supernatant when the modified glucomannan was dissolved in an ethanol aqueous solution was defined as S 50 (%), and the viscosity of a 1% by mass aqueous solution of the modified glucomannan at 25°C is V (mPa s), 50 and V satisfies the conditions of the following formula (B1), the following formula (B2), the following formula (B3), and the following formula (B4). V<1000 and 7≦S 50 (B1) 1000≦V≦5000 and 5≦S 50 (B2) 5000 <V≦13540 かつ 2.1≦S 50 (B3) 13540 <V かつ 1≦S 50 (B4) [1-2] The modified glucomannan according to [1] or [1-1], wherein the ratio of the acetate ion concentration in the modified glucomannan to the acetate ion concentration in the glucomannan before modification of the modified glucomannan is 0.95 or more. [1-3] The modified glucomannan according to [1], [1-1] or [1-2], wherein the chloride ion concentration in the modified glucomannan is 3 w / w% or less. [1-4] The modified glucomannan according to any one of [1] and [1-1] to [1-3], wherein the modified glucomannan has an electrical conductivity of 10 μS / m or less in a 0.05% by mass aqueous solution.

[0011] In other aspects, the present invention also relates to the following inventions. [2-1] The weight average molecular weight of the modified glucomannan is M 1 and the viscosity of a 1% by mass aqueous solution of the modified glucomannan at 25°C is V (mPa s), M 1 The modified glucomannan according to [2], wherein V satisfies the conditions of the following formula (A1), the following formula (A2), and the following formula (A3).

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[0012] In other aspects, the present invention also relates to the following inventions. [3-1] The weight average molecular weight of the modified glucomannan is M 1 and the viscosity of a 1% by mass aqueous solution of the modified glucomannan at 25°C is V (mPa s), M 1 The modified glucomannan according to [3], wherein V satisfies the conditions of the following formula (A1), the following formula (A2), and the following formula (A3).

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[0013] In other aspects, the present invention also relates to the following inventions. [4-1] The weight average molecular weight of the modified glucomannan is M 1 and the viscosity of a 1% by mass aqueous solution of the modified glucomannan at 25°C is V (mPa s), M 1 The modified glucomannan according to [4], wherein V satisfies the conditions of the following formula (A1), the following formula (A2), and the following formula (A3).

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[0014] In other aspects, the present invention also relates to the following inventions. [5-1] The weight average molecular weight of the modified glucomannan is M 1 and the viscosity of a 1% by mass aqueous solution of the modified glucomannan at 25°C is V (mPa s), M 1 The modified glucomannan according to [5], wherein V satisfies the conditions of the following formula (A1), the following formula (A2), and the following formula (A3).

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[0015] According to the present invention, a modified glucomannan having excellent viscosity expression and novel properties can be provided. [Brief description of the drawings]

[0016] [Figure 1] 1 is a graph showing the relationship between weight average molecular weight M1 and viscosity V in modified glucomannans according to Examples and Comparative Examples. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] Hereinafter, an embodiment of the present invention will be described, however, the present invention is not limited to the following embodiment.

[0018] Glucomannan is a β-1,4-glycosidic bond between glucose and mannose in a ratio of approximately 2:3. In this specification, "glucomannan" includes, for example, konjac powder itself containing glucomannan, in addition to those obtained by purifying konjac powder with alcohol.

[0019] In this specification, the term "modified glucomannan" refers to a modified product of glucomannan obtained by modifying the above glucomannan by some method. The modified glucomannan may be obtained by cutting the main chain of glucomannan to reduce its molecular weight, that is, the modified glucomannan can also be called a "low molecular weight glucomannan" that is reduced in molecular weight by cutting the main chain of glucomannan.

[0020] The weight average molecular weight (M 1 ) is not particularly limited, for example, 1.0×10 6 That's it, 1.2 x 10 6 That's it, 1.5 x 10 6 That's it, 1.8 x 10 6 or more, or 2.0 x 10 6 may be greater than or equal to 5.0×10 6 Below, 4.0 x 10 6 Below, 3.5 x 10 6 Below, 3.3 x 10 6 Below, 3.0 x 10 6 Below, 2.9 x 10 6 Below, 2.8 x 10 6 The following is 2.7 x 10 6 The following is 2.6 x 10 6 Less than or equal to 2.5×10 6 It may be the following:

[0021] The weight average molecular weight (M 1) was measured as a pullulan equivalent value by gel permeation chromatography (GPC).

[0022] The viscosity (V) of the modified glucomannan of the present invention may be, for example, 500 mPa·s or more, 700 mPa·s or more, 800 mPa·s or more, 900 mPa·s or more, or 1000 mPa·s or more, and may be 40,000 mPa·s or less, 35,000 mPa·s or less, 30,000 mPa·s or less, 25,000 mPa·s or less, 20,000 mPa·s or less, 15,000 mPa·s or less, 13,540 mPa·s or less, 10,000 mPa·s or less, 8,500 mPa·s or less, 7,000 mPa·s or less, or 5,000 mPa·s or less.

[0023] In this specification, the viscosity (V) (mPa s) is measured by preparing a 1% by mass aqueous solution of modified glucomannan and measuring this aqueous solution using a B-type viscometer (for example, product name "TVB-10M", manufactured by Toki Sangyo Co., Ltd.) at 25°C, rotor No. 3, and at 12 rpm for 10,000 ≧V, 6 rpm for 20,000 ≧V, and 3 rpm for 40,000 ≧V.

[0024] In a non-limiting aspect, the modified glucomannan according to the first embodiment has a weight average molecular weight of M 1 and the viscosity of a 1% by mass aqueous solution of modified glucomannan at 25°C is V (mPa s), M 1 and V is a modified glucomannan that satisfies the conditions of the following formulae (A1), (A2), and (A3). The modified glucomannan that satisfies these conditions has more suppressed deacetylation than conventional modified glucomannans and is excellent in viscosity expression.

[0025]

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[0026] In the modified glucomannan of this embodiment, when V satisfies the above formula (A1), V may also satisfy the following formulas (A2') and (A3').

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[0027] In one embodiment, a in formula (A2′) may be a numerical value of 255 or more and 300 or less, specifically, 255, 260, 265, 270, 275, 280, 285, 290, 295, or 300.

[0028] In one embodiment, b in formula (A2') is 8.6×10 -7 More than 9.4×10 -7 The following values ​​may be used: -7 , 8.7×10 -7 , 8.71×10 -7 , 8.72×10 -7 , 8.73×10 -7 , 8.74×10 -7 , 8.75×10 -7 , 8.76×10 -7 , 8.77×10 -7 , 8.78×10 -7 , 8.79×10 -7 , 8.8×10 -7 , 8.81×10 -7 , 8.82×10 -7 , 8.83×10 -7 , 8.84×10 -7 , 8.85×10 -7 , 8.86×10 -7 , 8.87×10 -7 , 8.88×10 -7 , 8.89×10 -7 , 8.9×10 -7 , 9.0×10-7 , 9.1×10 -7 , 9.2×10 -7 , 9.3×10 -7 or 9.4 x 10 -7 It may be.

[0029] In another embodiment, in formula (A2′), a is a numerical value of 50 or more and 75 or less, and b is 1.63×10 -6 Above 1.70 x 10 -6 Specifically, a may be 50, 55, 60, 65, 70, or 75, and b may be 1.63×10 -6 , 1.64×10 -6 , 1.65×10 -6 , 1.66×10 -6 , 1.67×10 -6 , 1.68×10 -6 , 1.69×10 -6 or 1.70 x 10 -6 It may be.

[0030] In one embodiment, c in formula (A3') may be a numerical value of 90 or more, specifically 90, 95, 100, 105, 110, 115, 120, 125, 130, 135, 140, 145, 150, 155, 160, 165, 170, 175, 180, 185, 190, 195, 200, 205, 210, 215, 220, 225, 230, 235, 240, 245, 250, 255, 260, 265, 270, 275, 280, 285, 290, 295, or 300. There is no particular upper limit to c, but it may be, for example, 400 or less, 375 or less, or 350 or less.

[0031] In one embodiment, d in formula (A3') is 1.63×10 -6 Above 1.70 x 10 -6 The following numerical value may be used, specifically, 1.63×10 -6 , 1.64×10 -6 , 1.65×10 -6 , 1.66×10 -6 , 1.67×10 -6 , 1.68×10 -6, 1.69×10 -6 or 1.70 x 10 -6 It may be.

[0032] In the modified glucomannan according to this embodiment, from the viewpoint of superior viscosity expression, when V satisfies the above-mentioned formula (A1), it is preferable that V satisfies the following formula (A2-1), formula (A2-2) or formula (A2-3).

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[0033] In the modified glucomannan according to this embodiment, when V satisfies the above formula (A1), it is preferable that V satisfies the following formula (A3-1) or formula (A3-2).

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[0034] That is, the modified glucomannan according to this embodiment is M 1and V may satisfy the above-mentioned formulas (A1), (A2) and (A3-1), may satisfy the formulas (A1), (A2) and (A3-2), may satisfy the formulas (A1), (A2-1) and (A3), may satisfy the formulas (A1), (A2-1) and (A3), may satisfy the formulas (A1), (A2-1) and (A3-1), may satisfy the formulas (A1), (A2-1) and (A3-2), may satisfy the formulas (A1), (A2-2) and (A3-2). and (A3), or may satisfy formulas (A1), (A2-2) and (A3-1), or may satisfy formulas (A1), (A2-2) and (A3-2), or may satisfy formulas (A1), (A2-3) and (A3), or may satisfy formulas (A1), (A2-3) and (A3-1), or may satisfy formulas (A1), (A2-3) and (A3-2).

[0035] In a non-limiting embodiment, the modified glucomannan according to the second embodiment has a recovery rate in the supernatant when the modified glucomannan is dissolved in an aqueous ethanol solution of S 50 (%), and the viscosity of a 1% by mass aqueous solution of modified glucomannan at 25°C is V (mPa s). 50 and V are modified glucomannans that satisfy the conditions of the following formulae (B1), (B2), and (B3): Modified glucomannans that satisfy these conditions are more inhibited in deacetylation than conventional modified glucomannans, and are excellent in viscosity expression. V<1000 and 7≦S 50 (B1) 1000≦V≦5000 and 5≦S 50 (B2) 5000 <V≦13540 かつ 2.1≦S 50 (B3)

[0036] The modified glucomannan according to this embodiment may be a modified glucomannan that satisfies the above formula (B1), the above formula (B2), the above formula (B3), and the following formula (B4). 13540 <V かつ 1≦S 50 (B4)

[0037] In this specification, the term "recovery rate (S 50 ) (%)" is a value expressed as a percentage obtained by dissolving 1 g of modified glucomannan in a 50% (v / v) aqueous ethanol solution, centrifuging at 4 ° C., 8000 g, 45 minutes, separating the supernatant (supernatant 1) and the precipitate, dissolving the precipitate in a 50% (v / v) aqueous ethanol solution, centrifuging at 4 ° C., 8000 g, 45 minutes, separating the supernatant (supernatant 2) and the precipitate, dissolving the precipitate in a 50% (v / v) aqueous ethanol solution, centrifuging at 4 ° C., 8000 g, 45 minutes, separating the supernatant (supernatant 3) and the precipitate, and dividing the total amount (dry solid content) of modified glucomannan contained in the supernatants 1 to 3 by the input amount of modified glucomannan (dry solid content in 1 g). Specifically, it may be a value measured by the method described in the examples described below. In this test, when glucomannan was simply dissolved in water, it was difficult to confirm its solubility due to the viscosity that developed. Therefore, measurements were performed in an alcohol solution, which makes it somewhat less soluble but allows confirmation of solubility.

[0038] In formula (B1), S 50 From the viewpoint of obtaining a more excellent viscosity expression property of the modified glucomannan, when the above-mentioned V is less than 1000 mPa·s, the S may be 8% or more, 8.5% or more, 9% or more, 9.5% or more, 10% or more, 10.5% or more, or 11% or more. 50 may be 30% or less, 25% or less, or 20% or less when the above-mentioned V is less than 1000 mPa·s.

[0039] In formula (B2), S 50 From the viewpoint of obtaining a more excellent viscosity expression property of the modified glucomannan, when the above-mentioned V is 1000 mPa·s or more and 5000 mPa·s or less, S may be 5.5% or more, 6% or more, 6.5% or more, or 7% or more. 50 may be 30% or less, 25% or less, 20% or less, or 15% or less when the above-mentioned V is 1000 mPa·s or more and 5000 mPa·s or less.

[0040] In formula (B3), S 50 From the viewpoint of obtaining a more excellent viscosity expression of the modified glucomannan, when the above-mentioned V is more than 5000 mPa·s and not more than 13540 mPa·s, it may be 2.2% or more, 2.3% or more, 2.4% or more, 2.5% or more, 2.6% or more, 2.7% or more, 3% or more, 3.5% or more, or 4% or more. 50 When the above-mentioned V is more than 5000 mPa·s and not more than 13540 mPa·s, it may be 30% or less, 25% or less, 20% or less, 15% or less, or 10% or less.

[0041] In formula (B4), S 50 From the viewpoint of obtaining a more excellent viscosity expression of the modified glucomannan, when the above-mentioned V exceeds 13,540 mPa·s, the S may be 1.1% or more, 1.2% or more, 1.3% or more, 1.4% or more, 1.5% or more, 1.6% or more, 1.7% or more, 1.8% or more, 1.9% or more, or 2% or more. 50 may be 30% or less, 25% or less, 20% or less, 15% or less, 10% or less, or 5% or less when the above-mentioned V exceeds 13,540 mPa·s.

[0042] In a non-limiting embodiment, the modified glucomannan according to the third embodiment is a modified glucomannan having a ratio of acetate ion concentration in the modified glucomannan to acetate ion concentration in the glucomannan before modification of 0.95 or more. The modified glucomannan satisfying this condition has more suppressed deacetylation than conventional modified glucomannans, and has excellent viscosity expression.

[0043] In this specification, the acetate ion concentration in the glucomannan before modification and the modified glucomannan means a value calculated by the following method. The glucomannan before modification or modified glucomannan is stirred at room temperature for 30 minutes in an alkaline aqueous solution (pH 12) at a concentration of 0.5% by mass to carry out an alkaline hydrolysis reaction. The amount of acetate ions liberated in the alkaline aqueous solution after the reaction is then measured by ion chromatography. The acetate ion concentration in the glucomannan before modification and modified glucomannan is calculated by dividing the measured amount of acetate ions by the amount of dry solids. Specifically, the acetate ion concentration may be a value measured by the method described in the Examples below.

[0044] The ratio of the acetate ion concentration in the modified glucomannan to the acetate ion concentration in the glucomannan before modification is a value calculated by the following formula. Ratio = Acetate ion concentration in glucomannan before modification / Acetate ion concentration in modified glucomannan In this specification, the "ratio" expressed as a percentage is also referred to as the "remaining amount of acetyl groups (%)."

[0045] The ratio may be 0.94 or more, preferably 0.945 or more, 0.95 or more, more preferably 0.955 or more, 0.96 or more, 0.965 or more, 0.97 or more, 0.975 or more, or 0.98 or more, and may be 1.

[0046] In a non-limiting embodiment, the modified glucomannan according to the fourth embodiment is a modified glucomannan having a chloride ion concentration of 3 w / w% or less. The modified glucomannan satisfying this condition has a suppressed deacetylation compared to conventional modified glucomannans, and has excellent viscosity expression.

[0047] In this specification, the chloride ion concentration in modified glucomannan means a value calculated by the following method. The modified glucomannan is stirred at room temperature for 30 minutes in an alkaline aqueous solution (pH 12) at a concentration of 0.5% by mass. The amount of chloride ions in the alkaline aqueous solution is then measured by ion chromatography. The chloride ion concentration in the modified glucomannan is calculated by dividing the measured amount of chloride ions by the amount of dry solids. Specifically, the value may be measured by the method described in the Examples below. The chloride ion concentration in the glucomannan before modification can also be calculated in the same manner.

[0048] The chloride ion concentration may more preferably be 2.5 w / w% or less, 2 w / w% or less, 1.5 w / w% or less, 1 w / w% or less, 0.5 w / w% or less, 0.3 w / w% or less, or 0.1 w / w% or less.

[0049] In a non-limiting embodiment, the modified glucomannan according to the fifth embodiment is a modified glucomannan having an electrical conductivity of 10 μS / m or less in a 0.05% by mass aqueous solution of the modified glucomannan. The modified glucomannan satisfying this condition has more suppressed deacetylation than conventional modified glucomannans and has excellent viscosity expression.

[0050] The electrical conductivity can be measured by an electrical conductivity meter equipped with an immersion type electrical conductivity cell (for example, "3551-10D" manufactured by Horiba, Ltd.) while stirring the aqueous solution of the modified glucomannan.

[0051] The electrical conductivity of the modified glucomannan in a 0.05% by mass aqueous solution is more preferably 9.5 μS / m or less, 9 μS / m or less, 8.5 μS / m or less, 8 μS / m or less, 7.5 μS / m or less, 7 μS / m or less, 6.5 μS / m or less, 6 μS / m or less, 5.5 μS / m or less, 5 μS / m or less, or 4.5 μS / m or less. The electrical conductivity may be, for example, 1 μS / m or more, or 3 μS / m or more.

[0052] The modified glucomannan of the present invention may have at least one aspect selected from the specific aspects described in the first embodiment, the specific aspects described in the second embodiment, the specific aspects described in the third embodiment, the specific aspects described in the fourth embodiment, and the specific aspects described in the fifth embodiment, or may have a combination of two or more aspects, or may have all five aspects.

[0053] The modified glucomannan according to this embodiment can be used for food material applications either as the modified glucomannan itself or as a preparation (composition) mixed with other ingredients acceptable as food.

[0054] Other ingredients contained in the formulation are not particularly limited as long as they are acceptable as food, and examples thereof include sugars, other polysaccharides, modified starches, salts, and commonly used excipients. Examples of sugars include glucose, fructose, and sucrose. Examples of other polysaccharides include carrageenan, xanthan gum, locust bean gum, guar gum, agar, curdlan, and carboxymethylcellulose. Examples of modified starches include acetylated adipate crosslinked starch, hydroxypropyl starch, and hydroxypropylated phosphate crosslinked starch. Examples of salts include potassium chloride, calcium lactate, and trisodium citrate. Examples of commonly used excipients include dextrin, glucose, and the like.

[0055] In this specification, the term "food material" refers to a material used to produce a food composition. Examples of food compositions include processed meat products, fish paste products, processed grain products, side dishes, health foods, confectioneries, beverages, seasonings, etc. The food material does not include the food composition itself that is consumed directly.

[0056] Next, the method for producing the modified glucomannan according to the present embodiment will be described. The method for producing the modified glucomannan according to the present embodiment preferably includes a step of modifying the glucomannan by heating the glucomannan (including konjac flour) at 100°C or higher in a sealed state without applying a shear force (hereinafter also referred to as a "heating step").

[0057] In the heating step, the glucomannan is heated in a sealed state at 100° C. or higher without applying a shear force. "Without applying a shear force" means that operations such as stirring and kneading are not performed in the heating step.

[0058] The heating step can be carried out by putting the glucomannan in a heat-resistant container or a heat-resistant bag. The heat-resistant container and the heat-resistant bag are preferably pressure-resistant. Examples of the heat-resistant container include general heat-resistant containers made of metal, ceramics, and glass. Examples of the heat-resistant bag include a retort bag (retort pouch) and the like.

[0059] The glucomannan before modification may be in a powder form. That is, in the heating step, the powdered glucomannan can be heated as it is to obtain a powdered modified glucomannan.

[0060] In the heating step, heating can be performed using a general heating device. The heating device used in the heating step may be a high-temperature, high-pressure sterilizer (such as a so-called retort sterilizer) that is commonly used in food manufacturing plants.

[0061] The temperature at which glucomannan is heated (heating temperature) is 100° C. or higher. This makes it possible to obtain a sufficiently modified glucomannan, and a modified glucomannan with excellent viscosity expression can be obtained. The heating temperature is preferably 100 to 180° C., and more preferably 110 to 150° C. In the heating step, the heating temperature may be constant, or may be increased or decreased stepwise or continuously.

[0062] The time for heating the thickening polysaccharide (heating time) can be appropriately set depending on the heating temperature. The heating time may be, for example, 5 to 600 minutes, preferably 10 to 300 minutes, and more preferably 20 to 240 minutes.

[0063] The heating step is preferably performed under conditions where the F value is 50 or more. The F value is used as an index to define the sterilization strength of retort foods and the like. The F value is defined as F value=1 when heated at 121°C for 1 minute. The F value when heated at T°C for t minutes is calculated by the following formula (A).

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[0064] In formula (A), T represents the heating temperature (unit: °C), t represents the heating time at T °C (unit: min), and Z represents the bacterium coefficient of Clostridium botulinum that forms heat-resistant spores. In this specification, the F value is calculated assuming Z is 12.

[0065] The F value may be 60 or more, 70 or more, 80 or more, 90 or more, 100 or more, 150 or more, 200 or more, 300 or more, 400 or more, or 500 or more, and may be 600 or less, 700 or less, 800 or less, 900 or less, 1000 or less, 5000 or less, 10,000 or less, or 50,000 or less.

[0066] In the modified glucomannan of this embodiment, by adopting the above-mentioned production method or by adjusting the production conditions (heating time, heating temperature, etc.) in the production method, a modified glucomannan having the characteristics unique to this embodiment described above can be obtained. EXAMPLES

[0067] The present invention will be described in more detail below with reference to examples, although the present invention is not limited to the following examples.

[0068] <Production Example: Production of Modified Glucomannan> [Example 1] Powdered glucomannan was placed in a commercially available retort pouch, sealed, and placed in a retort sterilizer for heat treatment. The heat treatment was carried out at 128°C for 60 minutes. After the heat treatment, the retort pouch was allowed to cool and then opened to obtain modified glucomannan.

[0069] [Example 2] A modified glucomannan was obtained in the same manner as in Example 1, except that the heat treatment conditions were changed to 128° C. for 120 minutes.

[0070] [Example 3] A modified glucomannan was obtained in the same manner as in Example 1, except that the heat treatment conditions were changed to 128° C. for 180 minutes.

[0071] [Example 4] A modified glucomannan was obtained in the same manner as in Example 1, except that the heat treatment conditions were changed to 128° C. for 240 minutes.

[0072] [Example 5] A modified glucomannan was obtained in the same manner as in Example 1, except that the heat treatment conditions were changed to 128° C. for 300 minutes.

[0073] [Example 6] A modified glucomannan was obtained in the same manner as in Example 1, except that the heat treatment conditions were changed to 128° C. for 360 minutes.

[0074] [Example 7] A modified glucomannan was obtained in the same manner as in Example 1, except that the heat treatment conditions were changed to 128° C. for 420 minutes.

[0075] [Reference example 1] The powdered glucomannan used as the raw material in Examples 1 to 7 was used for evaluation as pre-modified glucomannan.

[0076] [Comparative Example 1] Konjac flour was added to 0.275% hydrochloric acid heated to 80±5°C to a concentration of about 5% and dissolved, then the heating was stopped and the mixture was allowed to react at room temperature for one day to perform acid decomposition treatment. After the reaction was completed, the same amount of ethanol (95%) as the reaction solution was added to precipitate modified glucomannan. This was neutralized to pH 5 to 7 by adding 1N sodium hydroxide aqueous solution, stirred, dehydrated, dried, and pulverized to obtain the modified glucomannan according to Comparative Example 1.

[0077] [Comparative Example 2] A modified glucomannan was obtained in the same manner as in Comparative Example 1, except that the hydrochloric acid concentration was changed to 0.30%.

[0078] [Comparative Example 3] A modified glucomannan was obtained in the same manner as in Comparative Example 1, except that the hydrochloric acid concentration was changed to 0.35%.

[0079] [Comparative Example 4] A modified glucomannan was obtained in the same manner as in Comparative Example 1, except that the hydrochloric acid concentration was changed to 0.40%.

[0080] [Comparative Example 5] A modified glucomannan was obtained in the same manner as in Comparative Example 1, except that the hydrochloric acid concentration was changed to 0.45%.

[0081] [Comparative Example 6] A modified glucomannan was obtained in the same manner as in Comparative Example 1, except that the hydrochloric acid concentration was changed to 0.50%.

[0082] [Reference example 2] The konjac flour used as the raw material in Comparative Examples 1 to 6 was washed with ethanol to increase the purity of the glucomannan, and this was used for evaluation as pre-modified glucomannan.

[0083] <Evaluation example: Evaluation of modified glucomannan> [Weight average molecular weight (M 1 ) and viscosity (V) measurements] The weight average molecular weight (M 1) was measured as a pullulan equivalent value using gel permeation chromatography (GPC). The measurement conditions are as follows. Column: OHPak SB-806M HQ 8.0 x 300 (Shodex) Eluent: 0.5M NaNO 3 aqueous solution Flow rate: 1.0mL Holding temperature: 40℃ Injection: 200μL

[0084] In addition, the viscosity (V) (mPa s) of a 1% by mass aqueous solution of the modified glucomannan at 25°C was measured using a B-type viscometer (product name "TVB-10M", manufactured by Toki Sangyo Co., Ltd.) at 25°C, rotor No. 3, and at 12 rpm for 10,000 ≧ V, 6 rpm for 20,000 ≧ V, and 3 rpm for 40,000 ≧ V. The measurement results are shown in Table 1.

[0085] [Evaluation of solubility in aqueous ethanol solution] The recovery rate (S 50 The calculated recovery rate (S 50 ) are shown in Table 1. (1) 1 g of modified glucomannan was dissolved in 200 mL of water, and 200 mL of ethanol was added thereto and stirred. (2) The solution in (1) was centrifuged at 4°C, 8,000 × g, and 45 minutes, and the precipitate and supernatant were separated. (3) 200 mL of water was added to the precipitate, and then 200 mL of ethanol was added and stirred. (4) After centrifugation under the same conditions as in (2), the precipitate and the supernatant were separated. (5) 200 mL of water was added to the precipitate, and then 200 mL of ethanol was added and stirred. (6) After centrifugation under the same conditions as in (2), the precipitate and supernatant were separated. (7) The supernatants recovered in (2), (4) and (6) were combined and concentrated under reduced pressure to about 200 mL at a heating condition of 45° C. or less, and then freeze-dried. The amount of solid content (g) obtained after drying was measured and used as the amount of modified glucomannan recovered. (8) 1 g of the modified glucomannan used in (1) was dried under normal pressure, and the amount of solids (g) obtained after drying was measured and used as the amount of modified glucomannan added. (9) Recovery rate (S 50 ) was calculated according to the following formula. Recovery rate (S 50 ) (%) = {amount of modified glucomannan recovered (g) / amount of modified glucomannan added (g)} × 100

[0086] [Calculation of acetate ion concentration and chloride ion concentration in modified glucomannan] 50 mL of water was placed in a 100 mL Erlenmeyer flask, and 0.25 g of the modified glucomannan produced while stirring was added and stirred for 15 minutes. 5 mL of 0.5 N sodium hydroxide aqueous solution was added thereto to adjust the pH to about 12, and the mixture was stirred at room temperature for 30 minutes to prepare an aqueous solution (0.5% by mass) of modified glucomannan. Since the glucomannan is completely deacetylated by this treatment, the total amount of acetate ions bound thereto can be measured. Similarly, an aqueous solution (0.5% by mass) of glucomannan before modification was also prepared. 10 mL of these aqueous solutions were placed in a 15 mL tube, 2.5 mL of 99.5% ethanol aqueous solution was added, and the mixture was shaken well and mixed, and centrifuged at 8000 rpm for 15 minutes. The acetate ion concentration and chloride ion concentration were measured by ion chromatography under the following conditions, and the amount of acetate ion and chloride ion in the aqueous solution were calculated. The glucomannan before modification in Reference Examples 1 and 2 were also measured in the same manner. Column: IonPac AS14A 4 x 250 mm (Thermo Fisher Scientific) Eluent: 8.0 mM Na 2 CO 3 / 1.0 mM NaHCO 3 Flow rate: 1.0mL Holding temperature: normal temperature Suppressor: ADRS600 (Thermo Fisher Scientific) Injection: 25μL

[0087] The ratio of the amount of acetate ions and the amount of chloride ions in the aqueous solution calculated by the above measurement to the dry solid content of the modified glucomannan and the unmodified glucomannan was calculated to obtain the acetate ion concentration and the chloride ion concentration in the modified glucomannan and the unmodified glucomannan.

[0088] The calculated acetate ion concentrations and chloride ion concentrations are shown in Table 1. In Table 1, the ratio of the acetate ion concentration in the modified glucomannan to the acetate ion concentration in the pre-modified glucomannan in Reference Example 1 is shown as the amount of remaining acetyl groups (%) in Examples 1 to 7, and the ratio of the acetate ion concentration in the modified glucomannan to the acetate ion concentration in the pre-modified glucomannan in Reference Example 2 is shown as the amount of remaining acetyl groups (%) in Comparative Examples 1 to 6.

[0089] [Measurement of electrical conductivity] 150 mL of ultrapure water was placed in a 200 mL beaker, and 66 mg of modified glucomannan was added while stirring to prepare a 0.05 mass% aqueous solution of modified glucomannan. While stirring this aqueous solution, the electrical conductivity (μS / m) was measured using an electrical conductivity meter equipped with an immersion type electrical conductivity cell (manufactured by Horiba, Ltd., "3551-10D"). The same measurement was performed for the glucomannan before modification in Reference Example 1. The results are shown in Table 1.

[0090] [Table 1]

[0091] FIG. 1 shows the weight average molecular weight (M 1 1 is a graph showing the relationship between M and viscosity (V). 1and V satisfied the conditions of the above-mentioned formulae (A1), (A2) and (A3), but the modified glucomannan according to the comparative example did not satisfy the conditions.

[0092] As shown in Table 1, in the modified glucomannan according to the embodiment, S 50 and V satisfied the conditions of the above formulas (B1), (B2) and (B3), but the modified glucomannan according to the comparative example did not satisfy these conditions. 50 and V also satisfied the condition of the above-mentioned formula (B4).

[0093] As shown in Table 1, the modified glucomannan of the Examples has a ratio of acetate ion concentration in the modified glucomannan to the acetate ion concentration in the glucomannan before modification (in Table 1, this ratio is shown as the remaining acetyl group amount (%) expressed as a percentage) of 0.95 or more, which is greater than that of the Comparative Example. This means that deacetylation in the modified glucomannan is further suppressed, and therefore the modified glucomannan of the Examples can be said to be a modified glucomannan with excellent viscosity expression in which the contradictory phenomena of "increased water solubility due to low molecular weight" and "decreased water solubility due to deacetylation" are less likely to occur.

Claims

1. A modified glucomannan, which is a modified product of glucomannan, The weight average molecular weight of the modified glucomannan is M １ and the viscosity of a 1% by mass aqueous solution of the modified glucomannan at 25° C. is V (mPa s), １ and V satisfies the conditions of the following formula (A1), the following formula (A2), and the following formula (A3). [0010] [0025] [0030]

2. A modified glucomannan, which is a modified product of glucomannan, The recovery rate in the supernatant when the modified glucomannan is dissolved in an ethanol aqueous solution is S ５０ (%), and the viscosity of a 1% by mass aqueous solution of the modified glucomannan at 25° C. is V (mPa s), ５０ and V satisfies the conditions of the following formula (B1), the following formula (B2), the following formula (B3), and the following formula (B4). V<1000 and 7≦S ５０ (B1) 1000≦V≦5000 and 5≦S ５０ (B2) 5000<V≦13540 and 2.1≦S ５０ (B3) 13540<V and 1≦S ５０ (B4)

3. A modified glucomannan, which is a modified product of glucomannan, A modified glucomannan, wherein the ratio of the acetate ion concentration in the modified glucomannan to the acetate ion concentration in the glucomannan before modification of the modified glucomannan is 0.95 or more.

4. A modified glucomannan, which is a modified product of glucomannan, The modified glucomannan has a chloride ion concentration of 3 wt% or less.

5. A modified glucomannan, which is a modified product of glucomannan, The modified glucomannan has an electrical conductivity of 10 μS / m or less in a 0.05 mass% aqueous solution of the modified glucomannan.

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