Method for producing an agarooligosaccharide-containing composition

Abstract

This invention provides a method for producing an agarooligosaccharide-containing composition that can improve yield and increase productivity. [Solution] The method for producing an agarooligosaccharide-containing composition according to the present invention comprises an extraction step of immersing red algae in water at 70 to 120°C to extract a red algae extract, and a decomposition step of hydrolyzing the polysaccharides contained in the extracted red algae extract, wherein in the decomposition step, the kinematic viscosity of the dispersion of the red algae extract at a temperature of 70°C is 5,000 to 300,000 mm². 2 The method is characterized by exposing the polysaccharide to acid by adjusting the exposure time to a range of / s to hydrolyze it.

Description

[Technical Field]

[0001] This invention relates to a method for producing an agarooligosaccharide-containing composition. [Background technology]

[0002] Agarooligosaccharides are known to possess properties that contribute to the treatment or prevention of certain diseases, as well as the maintenance or promotion of health, and are substances that can be used as active ingredients in pharmaceuticals and functional foods (Patent Document 1: Japanese Patent No. 4007760). For this reason, methods for producing them have been studied. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Patent No. 4007760 [Patent Document 2] Patent No. 6868668 [Overview of the project] [Problems that the invention aims to solve]

[0004] Patent document 2 (Japanese Patent Publication No. 6868668) describes a method for producing an agarobiose-containing composition that suppresses discoloration (yellowing) and can be stored for a long period of time in a colorless state. The process of producing agarooligosaccharides and obtaining the containing composition involves multiple steps, and it may be possible to further improve productivity by improving the technology related to each step. [Means for solving the problem]

[0005] The present invention has been made in view of the above circumstances and aims to provide a method for producing an agarooligosaccharide-containing composition that can improve yield and productivity.

[0006] The present invention solves the above-mentioned problem by a solution described below as one embodiment.

[0007] The present invention provides a method for producing an agarooligosaccharide-containing composition, comprising an extraction step of immersing red algae in water at 70 to 120°C to extract a red algae extract, and a decomposition step of hydrolyzing the polysaccharides contained in the extracted red algae extract, wherein in the decomposition step, the kinematic viscosity of the dispersion of the red algae extract at a temperature of 70°C is 5,000 to 300,000 mm². 2 The method is characterized by exposing the polysaccharide to acid by adjusting the exposure time to a range of / s to hydrolyze it.

[0008] According to this method, by adjusting the kinematic viscosity of the red algae extract dispersion at the hydrolysis reaction initiation point, where the dispersion is exposed to acid, to a predetermined range, the entire polysaccharide in the red algae extract can be homogeneously hydrolyzed throughout the decomposition process. Therefore, the retention of undecomposed or incompletely decomposed residues and over-decomposition are suppressed. As a result, the final yield can be improved. Furthermore, filtration efficiency is also improved, allowing for purification in a shorter time and increasing overall productivity. In addition, it is thought that the filtration effect is improved, promoting the removal of impurities, and ultimately making it possible to obtain high-quality agarooligosaccharide-containing products at a low cost. [Effects of the Invention]

[0009] According to the present invention, it is possible to provide a method for producing an agarooligosaccharide-containing composition that can improve yield and increase productivity. [Brief explanation of the drawing]

[0010] [Figure 1] Figure 1 is a flowchart showing an example of a method for producing an agarooligosaccharide-containing composition according to this embodiment. [Figure 2] Figure 2 is a chromatogram showing the results of Test 1. [Figure 3] Figure 3 is a photograph showing the results of Test 3. [Modes for carrying out the invention]

[0011] Hereinafter, a method for producing an agar oligosaccharide-containing composition according to the present embodiment will be described along the flowchart shown in FIG. 1. In the present application, agar oligosaccharides are a general term for oligosaccharides having 10 or less sugar units with a repeating structure of disaccharide agarobiose units, and include disaccharide agarobiose, tetrasaccharide agaro - tetrasaccharide, hexasaccharide agarobiose, octasaccharide agarobiose, and decasaccharide agarobiose. In the present application, an agar oligosaccharide-containing composition is obtained by hydrolyzing a red alga extract containing agarose and / or agaropectin, which are polysaccharides having agarobiose units in the molecule, and contains at least one oligosaccharide selected from agarobiose, agaro - tetrasaccharide, agarobiose, octasaccharide agarobiose, and decasaccharide agarobiose, and is a mixture in which most of the sugar composition is occupied by the oligosaccharide.

[0012] As shown in FIG. 1, the method for producing an agar oligosaccharide-containing composition according to the present embodiment is roughly divided into a step of extracting a red alga extract from red algae (red alga extract extraction step S1) and a subsequent step of hydrolyzing the red alga extract to produce agar oligosaccharides (agar oligosaccharide production step S2). Through the agar oligosaccharide production step S2, an agar oligosaccharide-containing composition is obtained.

[0013] The red alga extract extraction step S1 includes an alkali treatment step S101, an acid treatment step S102, an extraction step S103, a filtration step S104, a cooling step S105, and a concentration step S106. That is, using one or more types of red algae as raw materials, exposing them to alkali (alkali treatment step S101), exposing them to acid (acid treatment step S102), extracting the red alga extract with hot water (extraction step S103), filtering (filtration step S104), cooling to gelify (cooling step S105), and removing the moisture of the gelled product to concentrate the extracted components (concentration step S106). Steps other than the extraction step S103 are optional steps. Depending on the implementation or non - implementation and implementation modes (methods and degrees) of steps such as the cooling step S105 and the concentration step S106, red alga extracts can be obtained in various forms such as liquids, pastes, gels, dry solid substances, powders, etc. Hereinafter, each step will be described in detail.

[0014] The alkali treatment step S101 is a step of exposing red algae to alkali. Since red algae contain agarose and / or agaropectin, which are polysaccharides having agarobiose units in their molecules, they can be used as raw materials for the target product, agarooligosaccharide. Specifically, one or more types of red algae belonging to families such as Gelidiaceae, Pterocladiaceae, Gracilariaceae, Bangiaceae, and Ceramiaceae can be used as raw materials simultaneously. Freshly harvested individuals may be used, or dried individuals may be used. In addition, as the alkali to which the red algae are exposed, one or more types of alkali can be used from among sodium hydroxide, potassium hydroxide, calcium hydroxide, calcium oxide, ammonium hydroxide, etc.

[0015] Using this, step S101 allows the prepared red algae to be exposed to alkali by immersing them in an alkaline solution. The red algae may be added to a pre-prepared alkaline solution, or an alkaline solution may be prepared by adding alkali to a dispersion of red algae (adjusted to the desired alkaline range). In addition, in step S101, the red algae may be exposed to alkali while the alkaline solution in which they are immersed is heated.

[0016] The alkaline treatment in step S101 has the effect of removing functional groups (mainly sulfate groups of agaropectin, etc.) from the polysaccharide molecules of red algae using alkali, which is thought to facilitate the homogeneous extraction of polysaccharide molecules, which are the extractable components of red algae. As a result, the extraction performance is improved, and furthermore, the polysaccharide molecules in the extract are homogeneously hydrolyzed in the agarooligosaccharide production step S2, which is thought to improve the decomposition performance as well. As a result, improved yield and improved filtration efficiency can be achieved. However, since the amount of functional groups of polysaccharide molecules, for example, may differ slightly depending on the type and condition of the raw material red algae, it is advisable to appropriately determine whether or not to perform step S101 and the treatment depth described below.

[0017] The depth or effect of alkaline treatment is mainly determined by three factors: alkali strength, treatment temperature, and treatment time. The stronger the alkali (higher the pH), the higher the temperature, and the longer the treatment time, the deeper the treatment (the stronger the effect). If the treatment is too shallow, the functional group removal effect will not be sufficiently obtained, so it is basically preferable to perform a relatively deep treatment. However, if the treatment is too deep, the extracted components will dissolve, so it is best to perform a treatment that is moderately deep. As a specific example of treatment depth, when red algae are added to an alkaline solution that has been adjusted to a desired concentration and exposed to alkali, the alkali concentration of the solution can be adjusted to a range of 0.1 to 10.0 wt%. In addition, the temperature of the treatment solution in which the red algae are immersed in the alkaline solution can be adjusted to a range of 0 to 100°C. Furthermore, the treatment time can be adjusted to a range of 1 to 180 minutes. More preferably, the alkali concentration can be 5.0 ± 3 wt%, the treatment solution temperature can be 90 ± 10°C, and the treatment time can be 45 to 180 minutes. More preferably, the alkali concentration can be set to 5.0 ± 3 wt%, the treatment solution temperature to 90 ± 10°C, and the treatment time to 135 to 180 minutes. However, even if one or more of the conditions (alkali concentration, treatment solution temperature, and treatment time) do not fall within the above range, the alkali treatment can be performed to a depth similar to or a desired depth to the above settings by appropriately setting the other conditions.

[0018] When the alkaline treatment in step S101 is carried out within a range that does not exceed a moderate depth, the depth or effect is expressed as the sulfate group content in the red algae extract obtained through the red algae extract extraction step S1. Using this as an indicator, the lower the sulfate group content in the red algae extract, the higher the depth and effect of the alkaline treatment, which is preferable in terms of the quality of the red algae extract. Therefore, although this indicator is directly related to the depth and effect of the alkaline treatment when step S101 is carried out, it is also effective as an indicator of the quality of the red algae extract and, by extension, the quality of the agarooligosaccharide obtained therefrom, regardless of whether or not step S101 is carried out, and is also effective as an indicator of the quality of the agarooligosaccharide manufacturing method itself. Specifically, in the present invention, regardless of whether or not step S101 is performed, the sulfate group content [mass%] in the dry mass of the red algae extract obtained through the red algae extract extraction step S1 (at least extraction step S103) is preferably 1.5% by mass or less, more preferably 1.0% by mass, and more preferably 0.7% by mass or less (Example: Test 4). The sulfate group content in this red algae extract can be quantified by gravimetric method, and according to this method, sulfate groups are converted into sulfate ions (SO4). 2- It is captured and measured as follows. Details are explained in Example: Test 4.

[0019] After the alkaline treatment in step S101, the red algae can be washed with neutral water to remove the alkali. Washing can be done, for example, by draining the treated solution after the alkaline treatment and supplying fresh neutral water. This water change may be performed once or multiple times. Alternatively, as another method of alkali removal, the alkali may be neutralized and removed by adding acid. The purpose of adding acid here is to neutralize and remove the alkali in step S101 and to adjust the pH for the next step S102 or S103, and it is distinguished from the acid treatment in step S102 in terms of its significance and effect. Washing and acid addition may be carried out in appropriate combinations.

[0020] Acid treatment step S102 is a step in which red algae are exposed to acid. As the acid to which the red algae are exposed, one or more acids can be used from among inorganic acids such as hydrochloric acid, sulfuric acid, and nitric acid, and organic acids such as acetic acid, phosphoric acid, citric acid, malic acid, oxalic acid, lactic acid, and gluconic acid.

[0021] Using this, step S102 allows the dispersion of red algae to be adjusted to a desired acidity range and exposed to acid. "Exposing to acid" means bringing the entire surface of the red algae into contact with the acid, and this can be achieved by immersing the red algae in an acid solution. The acid solution may be prepared (adjusted to a desired acidity range) by adding acid to the dispersion of red algae, or the red algae may be added to a pre-prepared acid solution. In addition, in step S102, the acid solution in which the red algae are immersed may be stirred appropriately. Furthermore, heating the acid solution in which the red algae are immersed is not prohibited, but it is possible to obtain a certain treatment effect with an acid solution at room temperature (1-30°C), and for example, treatment may be performed with an acid solution at 10°C or below.

[0022] The acid treatment in step S102 has the effect of softening the cell walls of red algae and solubilizing minerals on the cell wall surface, which is thought to facilitate the homogeneous extraction of polysaccharide molecules, which are the extractable components of red algae. As a result, the extraction performance is improved, and furthermore, the polysaccharide molecules in the extract are homogeneously hydrolyzed in the agarooligosaccharide production step S2, which is thought to improve the decomposition performance as well. As a result, improved yield and improved filtration efficiency can be achieved. In addition, it has been found that agarooligosaccharides obtained by acid treatment have the effect of suppressing browning (adhesion of yellow color) (Example: Test 3). That is, when the agarooligosaccharide-containing composition produced by this embodiment is heat-treated, it remains colorless and transparent as before heating, or browning associated with heating is suppressed, making it possible to obtain particularly high-quality agarooligosaccharides.

[0023] The depth or effect of acid treatment is mainly determined by the acid strength; the stronger the acid (the lower the pH), the deeper the treatment (the stronger the effect). As a specific example of treatment depth, when an acid is added to a dispersion of red algae to prepare an acid solution (treatment solution) in the desired acid range and the material is exposed to the acid, it is preferable to set the pH of the treatment solution in the range of 1.5 to 5.0, more preferably in the range of 1.5 to 4.0, even more preferably in the range of 1.5 to 3.0, and still preferable in the range of 2.0 to 3.0 (Example: Test 3).

[0024] After the acid treatment in step S102, the red algae can be washed with neutral water to remove the acid. Washing can be done, for example, by draining the treatment solution after the acid treatment and supplying fresh neutral water. This water change may be performed once or multiple times. Since minerals solubilized along with the acid are removed by the wastewater during washing, the pH in the next step, extraction step S103, will be more stable, and consequently, the quality of the agarooligosaccharide obtained at the end will also be more stable. Alternatively, as another method of acid removal, the acid may be neutralized and removed by adding alkali. The purpose of alkali addition here is to neutralize and remove the acid in step S102 and to adjust the pH for the next step S103, and it is distinguished from the alkali treatment in the previous step S101 in terms of its significance and effect. Washing and alkali addition may be carried out in appropriate combinations.

[0025] Extraction step S103 is a step in which red algae are immersed in hot water to extract the red algae extract, and is a step in which the red algae extract is extracted using hot water at 70-120°C. In this step S103, the water (dispersion) in which the red algae are dispersed is adjusted to a pH of 5.0-8.0, which is neutral or close to neutral, and the water is heated under atmospheric pressure or appropriate pressure to a temperature of 70-120°C, and hot water extraction is performed for 1-3 hours to extract a red algae extract containing agarose and / or agaropectin.

[0026] The pH of water can be adjusted by adding any acid and / or alkali as a buffer. The acid and alkali used at this time are not limited, and the same alkali used in alkali treatment step S101 and the acid used in acid treatment step S102 can be used. However, the acid and alkali here are pH adjusting agents that regulate the progress of the extraction reaction, and are distinguished in significance and effect from the treatment agents used in the alkali treatment and acid treatment in the preceding steps S101 and S102.

[0027] In step S103, phosphate can be suitably added to the extract (water / hot water). The phosphate dissolves in water and, as described above, acts as a buffer to adjust the pH of the water. In addition, it also has the effect of chelating minerals remaining on the surface of the cell walls of red algae, which is thought to facilitate the homogeneous extraction of polysaccharide molecules, which are the extractable components of red algae. As a result, the extraction performance is improved, and consequently, in the subsequent agarooligosaccharide production step S2, the polysaccharide molecules in the extract can be hydrolyzed more homogeneously, and the decomposition performance is also thought to be improved. Thus, phosphate is suitable because it can act as an extraction accelerator that enhances extraction performance while buffering the pH during extraction.

[0028] Filtration step S104 is a step in which the red algae extract (extract) is purified by filtration. The filtration method is not limited, and conventional methods in this art, such as pressurized filtration using a filter press, can be used. Multiple filtration methods may be combined. Filter aids such as diatomaceous earth may also be used.

[0029] The cooling step S105 is a step in which the extract or the filtrate obtained by filtering it is cooled to gel. The red algae extract components are so-called agar components mainly composed of agarose and / or agaropectin, and they gel at temperatures below the freezing point of agar, usually 38°C or below. In this step S105, the mixture is preferably cooled to 33±3°C or below.

[0030] The concentration step S106 is a step in which the red algae extract components are concentrated by removing water from the extract or filtrate or the gelled product obtained by gelling them. Examples of concentration methods include concentration by freezing and thawing, concentration by pressing, and concentration using an evaporator (e.g., vacuum concentration). Multiple concentration methods may be combined. Depending on the degree of concentration, red algae extracts can be obtained in various forms such as liquid, paste, gel, or dried solid, or powdered red algae extract can be obtained by grinding the solid.

[0031] Through the red algae extract extraction process S1 described above, a red algae extract containing agarose and / or agaropectin, which are polysaccharides having agarobiose units in their molecules, is obtained from the raw material red algae.

[0032] The subsequent agarooligosaccharide manufacturing process S2 includes a decomposition process S207, a purification process S208, and a drying process S209. Specifically, the kinematic viscosity of the dispersion of the extracted red algae extract is adjusted and exposed to acid to hydrolyze the polysaccharides in the extract to produce oligosaccharide agarooligosaccharides (decomposition process S207), which are then purified (purification process S208) and dried (drying process S209). All steps except the decomposition process S207 are optional, and depending on whether or not the drying process S209 is performed and the embodiment (method and extent), agarooligosaccharide-containing compositions can be obtained in various forms such as liquid, paste, and powder. Each step will be described in detail below.

[0033] Decomposition step S207 is a step in which the dispersion of the extracted red algae extract is exposed to acid to hydrolyze the red algae extract, i.e., the polysaccharide molecules contained in the red algae extract. In this embodiment, in step S207, the kinematic viscosity of the red algae extract dispersion at a product temperature of 70°C is 5,000 to 300,000 mm². 2The reaction is initiated (started) by exposing the sample to acid, adjusting the kinematic viscosity to be within the range of / s. For example, in a method where red algae extract is dispersed in a pre-prepared acid solution, or acid is added to a dispersion of red algae extract (extract dispersion) (or an acid solution is mixed), this means adjusting the kinematic viscosity of the reaction solution, which is the acid solution in which the red algae extract is immersed, to the above range. Also, in a method where a solid acid is used as the stationary phase column and the mobile phase of the extract dispersion is passed through it to expose the sample to acid, this means adjusting the kinematic viscosity of the mobile phase, the extract dispersion, to the above range.

[0034] As the acid to which the extract is exposed, one or more acids can be used from among inorganic acids such as hydrochloric acid, sulfuric acid, and nitric acid, and organic acids such as acetic acid, phosphoric acid, citric acid, malic acid, oxalic acid, lactic acid, and gluconic acid. For example, the extract dispersion can be exposed to acid by immersing the red algae extract in one of these solutions (acid solution). Alternatively, a solid acid can be used as the acid, which maintains a solid form in the extract dispersion and has a cationizing functional group that exhibits hydrolytic activity. Examples of solid acids include natural minerals such as zeolites and montmorillonite and their acid-treated products, solidified acids obtained by impregnating and supporting liquid acids such as sulfuric acid and phosphoric acid on alumina, silica gel, diatomaceous earth, etc., alumina itself, cation exchange resins, cation exchange fibers, cation exchange membranes, and mixtures thereof. In other words, usable acids include both liquid and solid forms. Generally, the hydrolysis reaction can be accelerated by selecting a strong acid rather than a weak acid, a high concentration rather than a low concentration, and a high temperature rather than a low temperature. Similarly, solid acids can accelerate hydrolysis reactions more rapidly with stronger cation exchange resins than weaker ones, and the greater the amount used and the higher the operating temperature.

[0035] The red algae extract obtained through the red algae extract extraction process S1 can also exist in liquid or solid form. The liquid form of the red algae extract is the red algae extract dispersion itself. On the other hand, for the solid form of the red algae extract, for example, powders or dried solids can be dispersed in liquid again to prepare an extract dispersion, and pastes can also be dispersed with liquid as appropriate to prepare an extract dispersion. Furthermore, gels can be re-solved by heating, and water can be added as appropriate to prepare an extract dispersion.

[0036] Therefore, in step S207, for example, acid can be added to the extract dispersion (the acid solution can be mixed) so that the reaction solution, which is an acid solution in which the red algae extract is immersed, has a predetermined kinematic viscosity. In this way, when both the extract and the acid are liquids, the kinematic viscosity of the extract dispersion and the reaction solution can be adjusted simultaneously. Also, for example, a red algae extract in solid form can be dispersed in an acid solution or a solid acid-containing solution to achieve a predetermined kinematic viscosity. In this way, when the extract is solid, the preparation of the extract dispersion, the adjustment of its kinematic viscosity, and the preparation of the reaction solution can be performed simultaneously. Furthermore, for example, the extract dispersion can be exposed to acid by passing the mobile phase of the extract dispersion through a column of solid acid as the stationary phase. In this case, the extract dispersion adjusted to a predetermined kinematic viscosity can be passed through the column of solid acid to react.

[0037] In this embodiment, the kinematic viscosity of the red algae extract dispersion at a temperature of 70°C is 5,000 to 300,000 mm². 2The reaction is initiated by exposing the red algae extract to acid at a rate within the range of / s to start the hydrolysis reaction of polysaccharide molecules contained in the red algae extract. Although it is generally known that stirring of a reaction system promotes chemical reactions, when red algae extract is exposed to acid for hydrolysis, the agitability of the reaction solution naturally improves as the reaction progresses and polysaccharides are decomposed. Therefore, parameters related to the agitability of the reaction solution have not been considered in the art to which this invention belongs. On the other hand, the inventors hypothesized that if the agitability of the extract dispersion is not good, the reaction will occur heterogeneously throughout the extract, resulting in a heterogeneous molecular weight distribution of intermediates. As a result, undecomposed or incompletely decomposed residues may remain, or over-decomposition may occur, leading to a decrease in the final yield. Recognizing the particular importance of agitability in this art, the inventors focused on the parameters related to it. After diligent research, they found that the dispersion concentration of the extract is of certain importance, and further, they found that the kinematic viscosity of the extract dispersion at the hydrolysis reaction initiation point, when the extract dispersion is exposed to acid, greatly affects the final yield, leading to the present invention.

[0038] In other words, in this invention, the kinematic viscosity of the extract dispersion at a product temperature of 70°C at the hydrolysis reaction initiation point is 5,000 to 300,000 mm². 2 By adjusting the kinematic viscosity to be within the range of / s, it becomes possible to homogeneously hydrolyze the entire red algae extract through the decomposition step S207. In the process leading to the invention, although the kinematic viscosity was kept within a predetermined range to improve the agitation of the reaction solution, it was found that if the kinematic viscosity was set too low, the red algae extract would clump together and become difficult to break apart, conversely reducing dispersibility and causing the reaction to occur heterogeneously. As a result, the invention was realized as the optimal range in which the kinematic viscosity of the extract dispersion is kept below a certain level, improving agitation while maintaining a certain level of dispersibility of the extract, thereby improving the final yield and increasing productivity. By satisfying this, the final yield is improved, as is the filtration efficiency, allowing for purification in a shorter time and improving overall productivity. Furthermore, it is thought that the filtration effect is also improved, promoting the removal of impurities, and consequently making it possible to obtain high-quality agarooligosaccharide-containing products at low cost.

[0039] Furthermore, in the process of developing the invention, although the kinematic viscosity is basically adjusted by the dispersion concentration of the red algae extract, it was found that when attempting to adjust the dispersion concentration itself as a parameter related to the stirability of the reaction solution, the physical properties (stirability) of the extract dispersion may differ depending on the type of red algae, etc., even at the same dispersion concentration, making it difficult to uniformly define the optimal dispersion concentration, and in some cases, optimal stirability cannot be obtained. On the other hand, if the dispersion concentration of the extract is too low, the amount of extract subject to hydrolysis decreases, reducing productivity, so it is preferable to set a lower limit for the dispersion concentration of the extract. In this regard, in addition to the kinematic viscosity range described above, it is more preferable, for example, that the dispersion concentration of the red algae extract (the concentration of solid red algae extract added to the reaction solution) is 5 wt% or more, or in other words, that a dispersion of red algae extract at a concentration of 5 wt% or more is adjusted to the kinematic viscosity range described above and then exposed to acid.

[0040] As mentioned above, the kinematic viscosity of the extract dispersion is basically adjusted by the dispersion concentration of the red algae extract. Therefore, even though it is presumed that setting the kinematic viscosity too low will reduce the amount of extract itself in the extract dispersion and consequently decrease the yield, in reality, as shown in the example below, setting the kinematic viscosity too low tends to decrease not only the yield but also the filtration efficiency (Example: Test 2). This suggests that the decrease in kinematic viscosity has an unpredictable effect on the hydrolysis reaction itself. And, as mentioned above, it was confirmed that this effect is a problem with the dispersibility of the extract. The kinematic viscosity range according to the present invention is the optimal range found after much trial and error, given the existence of such unpredictable effects.

[0041] In the examples described below, the extract dispersion was adjusted to the above kinematic viscosity range and subjected to hydrolysis with acid, resulting in an improvement in the final yield from 5.80 to 5.90% to 10.60% (Example: Test 2). Furthermore, from the results of the examples, the kinematic viscosity range was found to be 5000 to 300000 mm². 2 / s is 5000~200000mm 2A range of / s is more preferable, 5000 to 120000 mm 2 / s is more preferable, 5000 to 60000 mm 2 / s is more preferable, 5000 to 30000 mm 2 / s is more preferable. The kinematic viscosity in the present application is a value measured and calculated at a product temperature of 70 °C using a B-type viscometer (TV-10, manufactured by Toki Sangyo Co., Ltd.) of a single cylindrical rotational viscometer based on the method described in JIS Z8803:2011 using a spindle of No. M4. The rotation speed of the spindle will be specifically shown in the examples.

[0042] In this step S207, the acid hydrolysis of the red algae extract containing agarose and / or agaropectin itself can be carried out in accordance with conventional methods (for example, Patent Documents 1 and 2). The type of acid, amount (concentration), and the accompanying pH of the reaction solution, reaction temperature, and reaction time can be appropriately set within the range that can achieve the purpose of decomposing polysaccharides (agarose and / or agaropectin) in the red algae extract into agarooligosaccharides. Therefore, if the extract dispersion liquid at the start point of the hydrolysis reaction is adjusted to the kinematic viscosity range according to this embodiment, other conditions can be set, for example, within the range described in Patent Documents 1 and 2, and the hydrolysis reaction can be carried out. As an example of specific reaction conditions, when using an acid solution or a solid acid-containing solution, the pH of the reaction solution can be adjusted to a range of 1.0 to 5.0, more preferably 1.0 to 4.0, and more preferably 1.0 to 3.0. Note that this pH is the pH at the time of preparing the reaction solution (at the start of the reaction), and the reaction solution is, as described above, an acid solution in which the red algae extract is immersed. Also, the temperature of the reaction solution can be adjusted to a range of 10 to 120 °C, more preferably 50 to 100 °C, more preferably 80 to 100 °C, and more preferably 90 to 100 °C. Also, the reaction time can be adjusted to a range of 30 minutes to 12 hours, more preferably 1 to 6 hours.

[0043] Through hydrolysis, agarose and agaropectin, polysaccharides containing agarobiose units in their molecules and contained in the red algae extract, are broken down into agarooligosaccharides such as agarobiose, agarotetraose, agarohexaose, agarooctaose, or agarodecaose by cleaving the α(1,3) glycosidic bond between D-galactopyranose and 3,6-anhydro-L-galactopyranose. In this way, agarooligosaccharides can be produced using red algae as a raw material, and an agarooligosaccharide-containing composition can be obtained. The agarooligosaccharide content can be analyzed by HPLC or the like (Example: Test 1).

[0044] After hydrolysis, remove the acid from the hydrolyzed decomposition solution as needed. Liquid acid can be removed by neutralizing it with alkali. Solid acid can be removed by solid-liquid separation using a sieve, gel filtration using a column, solid-liquid separation using a molecular weight fractionation membrane, etc. Multiple removal methods may be combined. Also, cool the decomposition solution to approximately room temperature as needed.

[0045] The purification step S208 is a step in which the agarooligosaccharide-containing composition (decomposition liquid) is purified by filtration or the like. The purification method is not limited, and conventional methods in this art, such as the removal of impurities using activated carbon or hollow fiber membranes, or pressurized filtration using a filter press, can be performed. Among these, for example, activated carbon treatment can adsorb and remove low molecular weight impurities. Multiple purification methods may be combined. Filter aids such as diatomaceous earth may also be used.

[0046] According to this embodiment, by adjusting the kinematic viscosity of the red algae extract dispersion in the preceding step S207 to homogeneously hydrolyze the entire polysaccharide in the extract, the purification efficiency in the present step S208 is improved. That is, the remaining undegraded or incompletely degraded residue, which is high molecular weight and relatively viscous, is suppressed, thereby suppressing clogging of the filter material (filter agent), and as a result the filtration efficiency is improved, making purification possible in a shorter time. In addition, it is thought that the filtration effect is also improved, further promoting the removal of impurities, and consequently it becomes possible to obtain high-quality agarooligosaccharide-containing products at a low cost. Furthermore, by carrying out the alkali treatment step S101 and / or the acid treatment step S102, the purification efficiency can be further improved and browning can be suppressed, making it possible to obtain even higher quality agarooligosaccharide-containing products (Examples: Test 2-Test 5).

[0047] The drying step S209 is a step of drying the decomposition solution or its purified solution. By removing moisture using conventional methods in this art, such as freeze-drying, a powdered agarooligosaccharide-containing composition is obtained.

[0048] According to the method for producing the agarooligosaccharide-containing composition according to this embodiment, it is possible to improve the yield and increase the productivity of agarooligosaccharides. [Examples]

[0049] [Test 1] 1 kg of dried Gracilaria was added to 20 kg of 5 wt% sodium hydroxide (NaOH) solution and immersed for 2 hours while heating at 90°C. The NaOH solution was drained, and the solution was thoroughly washed with water to remove the alkali. This Gracilaria was added to 20 kg of water, and then sulfuric acid (H2SO4) solution was added to adjust the pH to 2.0. After the Gracilaria was accustomed to the acid, the H2SO4 solution was drained, and 20 kg of fresh water was added. 5 g of disodium phosphate (Na2HPO4) was then added to adjust the pH to 7.0, and extraction was carried out for 2 hours while heating at 97°C. Subsequently, this extract was filtered, the filtrate was cooled to room temperature, and then compressed and concentrated using a filter press. It was further dried with hot air at 90°C and pulverized to obtain a powdered Gracilaria extract. The obtained extract was tested for a kinematic viscosity of 30,000 mmHg at a temperature of 70°C. 2 The extract was dispersed in a 0.1 wt% H2SO4 solution to a concentration of / s. The dispersion concentration of the extract in the resulting dispersion (reaction solution) was 5 wt% or higher. The dispersion (reaction solution) was heated to 90°C and reacted for 3 hours and 30 minutes, then cooled to room temperature. 400 g of activated carbon was added to this decomposition solution to adsorb low molecular weight components. After filtering this solution, it was freeze-dried to obtain a powder.

[0050] In all subsequent tests, a single-cylindrical rotational viscometer, type B (TV-10, manufactured by Toki Sangyo Co., Ltd.), was used to adjust (measure) the kinematic viscosity. Using a spindle No. M4, the kinematic viscosity was measured and calculated at a sample temperature of 70°C. In Test 1 and Tests 3-5, the spindle rotation speed was set to 12 rpm, and the measured value was 30,000 mmHg. 2 A dispersion, i.e., the reaction solution, was prepared to achieve a spindle rotation speed of / s. The spindle rotation speeds for Experiment 2 are shown in Table 1 below.

[0051] The obtained powder was dissolved in distilled water and analyzed by liquid chromatography using the column described below, following the standard procedure for sugar composition analysis. The analytical conditions were as follows: Column: TSKgel G2500PW XL Inner diameter 7.8mm x Length 300mm Guard column: TSKgel guardgel (All products are manufactured by Tosoh Corporation; "TSKgel" is a registered trademark.) Mobile phase: Distilled water Flow rate: 0.4mL / min Column temperature: 30℃ Injection volume: 20μL Detector: Differential refractive index detector

[0052] Figure 2 shows the obtained chromatogram. In Figure 2, peak 1 (retention time 40.8 min) represents a disaccharide, peak 2 (retention time 38.4 min) represents a tetrasaccharide, peak 3 (retention time 36.8 min) represents a hexasaccharide, and peak 4 (retention time 35.8 min) represents an octasaccharide. Since it is well known that the components of the Gracilaria extract are so-called agar components mainly composed of agarose and agaropectin, it is almost certain that the disaccharide detected here is agarobiose, the tetrasaccharide is agarotetraose, the hexasaccharide is agarohexaose, and the octasaccharide is agaroctaose, all of which are oligosaccharides. Therefore, it was confirmed that the obtained powder is an agarooligosaccharide-containing composition.

[0053] [Exam 2] 1 kg of dried Gracilaria was added to 20 kg of 5 wt% sodium hydroxide (NaOH) solution and immersed for 2 hours while heating at 90°C. The NaOH solution was drained, and the solution was thoroughly washed with water to remove the alkali. This Gracilaria was added to 20 kg of water, and then sulfuric acid (H2SO4) solution was added to adjust the pH to 2.0. After the Gracilaria was accustomed to the acid, the H2SO4 solution was drained, and 20 kg of fresh water was added. 5 g of disodium phosphate (Na2HPO4) was then added to adjust the pH to 7.0, and extraction was carried out for 2 hours while heating at 97°C. Subsequently, this extract was filtered, the filtrate was cooled to room temperature, and then compressed and concentrated using a filter press. It was further dried with hot air at 90°C and pulverized to obtain powdered Gracilaria extract. The obtained extract was dispersed in 0.1 wt% H2SO4 solution so that the kinematic viscosity at a temperature of 70°C was as shown in Table 1. The dispersion concentration of the extract in the extract dispersion (reaction solution) was higher with increasing kinematic viscosity and lower with decreasing kinematic viscosity, but in all examples it was 5 wt% or higher. The extract dispersion (reaction solution) was reacted for 3 hours and 30 minutes while being heated to 90°C, and then cooled to room temperature. 400 g of activated carbon was added to this decomposition solution to adsorb low molecular weight impurities. After filtering this solution, it was freeze-dried to obtain an agarooligosaccharide-containing composition.

[0054] (Filtration efficiency) For the examples and comparative examples of acid hydrolysis of dispersions of Gracilaria extract, each adjusted to its respective kinematic viscosity, as described above, after cooling, the filtration efficiency was evaluated using an ADVANTEC vacuum filtration unit. The time required for a 100 mL sample of the decomposed solution to pass through a membrane filter with a pore size of 0.2 μm and a diameter of 47 mm was measured and evaluated according to the following criteria. Less than 60 seconds ◎ 60 seconds or more but less than 180 seconds ○ 180 seconds or more but less than 500 seconds △ 500 seconds or more ×

[0055] (Yield) The mass of the agarooligosaccharide-containing composition obtained was measured according to the formula below. Assuming a moisture content of 5 wt%, the dry mass, obtained by subtracting the moisture from the measured mass, was calculated as a mass percentage relative to the mass of the raw material red algae, Gracilaria (1 kg), and evaluated as yield [%] according to the following criteria. Yield [%] = [(Agarooligosaccharide-containing composition mass × 0.95) / Gracilaria mass] × 100 9.00% or higher ◎ 8.00% or more and less than 9.00% ○ 6.00% or more and less than 8.00% △ Less than 6.00% ×

[0056] The results are shown in Table 1. The spindle rotation speed used for kinematic viscosity adjustment (measurement) is also shown.

[0057] [Table 1]

[0058] As shown in Table 1, the kinematic viscosity of the dispersion of Gracilaria extract was 5,000 to 300,000 mm². 2 Examples 1-6, in which the kinematic viscosity was adjusted to / s and exposed to acid for reaction, showed improved yield compared to Comparative Examples 1 and 2, in which the kinematic viscosity was outside the specified range. Furthermore, the filtration efficiency was also improved when the kinematic viscosity was set to 5000 mm². 2 By adjusting it to a value greater than / s, it becomes possible to compare it to a lower value in Comparative Example 1 (1000mm 2 This is an improvement over (Example 1) and the kinematic viscosity is 300,000 mm². 2 By adjusting it to less than / s, it becomes possible to compare it to a higher comparative example 2 (600,000 mm 2 This is an improvement over (Example 6) and the kinematic viscosity is 5,000 to 300,000 mm². 2 Adjusting the setting to / s tended to improve filtration efficiency.

[0059] Based on the results of Test 2, the kinematic viscosity of the extract dispersion at the hydrolysis reaction initiation point where the extract dispersion is exposed to acid was determined to be between 5,000 and 300,000 mm². 2It is preferable to adjust it to a range of / s, between 5000 and 200000 mm. 2 A range of / s is more preferable, between 5000 and 120000 mm. 2 A range of / s is more preferable, between 5000 and 60000 mm. 2 A range of / s is more preferable, between 5000 and 30000 mm. 2 A range of / s is preferable.

[0060] [Exam 3] 1 kg of dried Gracilaria was added to 20 kg of 5 wt% sodium hydroxide (NaOH) solution and immersed for 2 hours while heating at 90°C. The NaOH solution was drained, and the solution was thoroughly washed with water to remove the alkali. This Gracilaria was added to 20 kg of water, and sulfuric acid (H2SO4) solution was added to adjust the pH to the values ​​shown in Table 2. After the Gracilaria was accustomed to the acid, the H2SO4 solution was drained, and 20 kg of fresh water was added. Furthermore, 5 g of disodium phosphate (Na2HPO4) was added to adjust the pH to 7.0, and then extraction was carried out for 2 hours while heating at 97°C. Subsequently, this extract was filtered, the filtrate was cooled to room temperature, and then compressed and concentrated using a filter press. It was further dried with hot air at 90°C and pulverized to obtain powdered Gracilaria extract. The obtained extract was subjected to a kinematic viscosity of 30,000 mmHg at a product temperature of 70°C. 2 The extract was dispersed in a 0.1 wt% H2SO4 solution to a concentration of / s. In each example, the dispersion concentration of the extract in the extract dispersion (reaction solution) was 5 wt% or higher. The extract dispersion (reaction solution) was reacted for 3 hours and 30 minutes while being heated to 90°C, and then cooled to room temperature. 400 g of activated carbon was added to this decomposition solution to adsorb low molecular weight impurities. After filtering this solution, it was freeze-dried to obtain an agarooligosaccharide-containing composition. In contrast to the above examples, in Reference Example 1, Gracilaria was exposed to alkali, and after alkali removal, 20 kg of water was simply added without acid treatment (pH: 7.0). Then, as in the example, disodium phosphate was added to perform extraction, and the obtained extract was hydrolyzed to obtain an agarooligosaccharide-containing composition.

[0061] In the same manner as in Test 2, the filtration efficiency and yield of each example were measured, calculated, and evaluated. In addition, Reference Example 1 was also included, and the resistance of agarooligosaccharides in the obtained agarooligosaccharide-containing compositions to browning was evaluated by the following method.

[0062] (Resistant to browning) The obtained agarooligosaccharide composition was dissolved in pure water at a concentration of 5 w / v% and heated at 85°C for 60 minutes. After cooling to 25°C ± 3°C, the color of the aqueous solution was visually evaluated according to the following criteria. It is colorless and transparent (same as before heating) ◎ It has a slightly yellowish tint. It has a yellowish tint. The results are shown in Table 2 and Figure 3. Figure 3 is a photograph of the aqueous solution of each agarooligosaccharide composition used in the color evaluation described above.

[0063] [Table 2]

[0064] As shown in Table 2, Examples 7-13, in which Gracilaria was treated with acid before hot water extraction, ensured a yield of at least 7.39% and a filtration efficiency of 153 seconds, demonstrating stable yield and filtration efficiency. Generally, the deeper the acid treatment with a relatively lower pH, the greater the tendency for yield and filtration efficiency to improve. Furthermore, as shown in Figure 3, regarding the color evaluation related to resistance to browning, the deeper the acid treatment with a lower pH, the more the yellowish tint faded and the closer it became to transparency, indicating the browning suppression effect of acid treatment. From the results of this 3 experiment, it is preferable to treat the red algae with acid before hot water extraction. In this case, it is preferable to adjust the pH of the red algae dispersion to the acidic range of 1.5-5.0 before exposure to acid, more preferably in the range of 1.5-4.0, more preferably in the range of 1.5-3.0, and even more preferably in the range of 2.0-3.0.

[0065] [Exam 4] 1 kg of dried Gracilaria was added to 20 kg of 5 wt% sodium hydroxide (NaOH) solution and immersed for the time shown in Table 3 while heating at 90°C. The NaOH solution was drained, and the solution was thoroughly washed with water to remove the alkali. This Gracilaria was added to 20 kg of water, and then sulfuric acid (H2SO4) solution was added to adjust the pH to 2.0. After the Gracilaria was accustomed to the acid, the H2SO4 solution was drained, and 20 kg of fresh water was added. Furthermore, 5 g of disodium phosphate (Na2HPO4) was added to adjust the pH to 7.0, and then extraction was carried out for 2 hours while heating at 97°C. Subsequently, this extract was filtered, the filtrate was cooled to room temperature, and then compressed and concentrated using a filter press. It was then hot-air dried at 90°C and pulverized to obtain powdered Gracilaria extract. The obtained extract had a kinematic viscosity of 30,000 mmHg at a product temperature of 70°C. 2 The extract was dispersed in a 0.1 wt% H2SO4 solution to a concentration of / s. In each example, the dispersion concentration of the extract in the extract dispersion (reaction solution) was 5 wt% or higher. The extract dispersion (reaction solution) was reacted for 3 hours and 30 minutes while heated to 90°C, and then cooled to room temperature. 400 g of activated carbon was added to this decomposition solution to adsorb low molecular weight impurities. After filtering this solution, it was freeze-dried to obtain an agarooligosaccharide-containing composition.

[0066] In the same manner as in Test 2, the filtration efficiency and yield of each example were measured, calculated, and evaluated. Furthermore, the sulfate group content of the Gracilaria extract before hydrolysis was measured and calculated using the method described below. The results are shown in Table 3.

[0067] (Sulfate group content) The sulfate group content of the Gracilaria extract was measured by a general gravimetric method. The powdered Gracilaria extract was dissolved in pure water by boiling, and hydrochloric acid and hydrogen peroxide were added to the solution to hydrolyze the extract. Barium chloride solution was added to this solution to precipitate barium sulfate as a sulfate salt, and the sulfate group content (SO4) was measured by the mass of the barium sulfate. 2- The mass of ) was calculated. This was divided by the mass of the powdered Gracilaria extract that had been measured in advance (dry mass of Gracilaria extract), and converted to a percentage to calculate the sulfate group content [mass %] of the Gracilaria extract.

[0068] [Table 3]

[0069] As shown in Table 3, Examples 14-17, in which Gracilaria was subjected to alkaline treatment by exposing it to alkali before hot water extraction (before acid treatment), ensured a yield of at least 8.37% and a filtration efficiency of 301 seconds, demonstrating stable yield and filtration efficiency. In general, the longer and deeper the alkaline treatment, the greater the tendency for yield and filtration efficiency to improve. In addition, the longer and deeper the alkaline treatment, the lower the sulfate group content of the extract tended to be, indicating a correlation between the depth of the alkaline treatment, which has the effect of removing functional groups from the polysaccharide molecules of red algae, and the sulfate group content of the extract. From the results of this test 4, it is preferable to perform alkaline treatment by exposing red algae to alkali before hot water extraction. In this case, it is preferable to set the treatment time for exposing the red algae to alkali to 45 minutes or more (45-180 minutes), more preferably 90 minutes or more (90-180 minutes), and even more preferably 135 minutes or more (135-180 minutes). Furthermore, in a method for producing agarooligosaccharides by hot water extraction of red algae and hydrolysis of the extract, it is preferable that the sulfate group content of the red algae extract obtained by hot water extraction is 1.5% by mass or less in dry mass, more preferably 1.0% by mass or less, and even more preferably 0.7% by mass or less.

[0070] [Exam 5] 1 kg of dried tengusa seaweed was added to 20 kg of 5 wt% sodium hydroxide (NaOH) solution and immersed for 2 hours while heating at 90°C. The NaOH solution was drained, and the tengusa was thoroughly washed with water to remove the alkali. This tengusa was added to 20 kg of water, and then sulfuric acid (H2SO4) solution was added to adjust the pH to 2.0. After the tengusa was accustomed to the acid, the H2SO4 solution was drained, and 20 kg of fresh water was added. Furthermore, 5 g of disodium phosphate (Na2HPO4) was added to adjust the pH to 7.5, and then extraction was carried out for 100 minutes while heating at 97°C. Subsequently, this extract was filtered, the filtrate was cooled to room temperature, and then compressed and concentrated using a filter press. It was then hot-air dried at 90°C and pulverized to obtain a powdered tengusa extract. The obtained extract had a kinematic viscosity of 30,000 mmHg at a product temperature of 70°C. 2 The extract was dispersed in a 0.1 wt% H2SO4 solution at a concentration of / s, and the dispersion concentration of the extract in the resulting dispersion (reaction solution) was 5 wt% or higher. The dispersion (reaction solution) was reacted for 3 hours and 30 minutes while being heated to 90°C, and then cooled to room temperature. 400 g of activated carbon was added to this decomposition solution to adsorb low molecular weight components. After filtering this solution, a powder was obtained by freeze-drying.

[0071] The obtained powder was dissolved in distilled water and analyzed by liquid chromatography, similar to the procedure in Test 1. As a result, peaks representing disaccharides, tetrasaccharides, hexasaccharides, and octasaccharides were detected, similar to the procedure in Test 1, confirming the presence of agarobiose, agarotetraose, agarohexaose, and agarooctaose. This confirmed that the obtained powder was an agarooligosaccharide-containing composition, and that an agarooligosaccharide-containing composition can be produced even when using tengusa (a type of seaweed) as a raw material. Furthermore, the filtration efficiency and yield were measured, calculated, and evaluated, similar to the procedure in Test 2. The results are shown in Table 4.

[0072] [Table 4]

[0073] As shown in Table 4, even when tengusa (a type of seaweed) was used as the raw material, the filtration efficiency and yield were good. It can be said that the method for producing agarooligosaccharides according to the present invention is generally applicable to any red algae that contains agarose and / or agaropectin, regardless of the species. [Explanation of symbols]

[0074] S1 Red algae extract extraction process S101 Alkali treatment process S102 Acid Treatment Process S103 Extraction process S104 Filtration process S105 Cooling process S106 Concentration process S2 Agarooligosaccharide Manufacturing Process S207 Decomposition process S208 Purification process S209 Drying process

Claims

1. The extraction process involves immersing red algae in water at 70-120°C to extract the red algae extract, The process includes a decomposition step of hydrolyzing the polysaccharides contained in the extracted red algae extract, In the aforementioned decomposition step, the kinematic viscosity of the dispersion of the red algae extract at a product temperature of 70°C is 5,000 to 300,000 mm². ２ The polysaccharide is hydrolyzed by exposing it to acid while adjusting the temperature to be within the range of / s. A method for producing an agarooligosaccharide-containing composition characterized by the above.

2. In the decomposition step, the dispersion of the red algae extract at a concentration of 5 wt% or more is adjusted to the kinematic viscosity range and exposed to acid. A method for producing the agarooligosaccharide-containing composition according to claim 1, characterized by the above.

3. The sulfate group content of the red algae extract obtained through the extraction process is 1.5% by mass or less in dry mass. A method for producing an agarooligosaccharide-containing composition according to claim 1 or claim 2, characterized by the above.

4. The extraction step further includes an acid treatment step in which the red algae are exposed to acid. A method for producing an agarooligosaccharide-containing composition according to claim 1 or claim 2, characterized by the above.

5. In the acid treatment step, the pH of the red algae dispersion is adjusted to an acidic range of 1.5 to 5.0 and exposed to acid. A method for producing the agarooligosaccharide-containing composition according to claim 4, characterized by the above.

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