Method for producing an agarooligosaccharide-containing composition

Abstract

Provided is a method for producing an agarooligosaccharide-containing composition, which can improve yield and productivity. 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 polysaccharides contained in the extracted red algae extract, wherein the decomposition step is carried out to obtain a dispersion of the red algae extract having a kinematic viscosity of 5,000 to 300,000 mm at a product temperature of 70°C. 2 The method is characterized in that the polysaccharide is hydrolyzed by exposure to an acid with an adjusted concentration so that the concentration is in the range of 1 / s.

Description

[Technical Field]

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

[0002] Agarooligosaccharides are known to have properties that contribute to the treatment or prevention of certain diseases and the maintenance or promotion of health, and are substances that can be used as active ingredients in pharmaceuticals and functional food ingredients in health foods (Patent Document 1: Japanese Patent No. 4007760). Therefore, 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 Summary of the Invention [Problem to be solved by the invention]

[0004] Patent Document 2 (Japanese Patent No. 6868668) describes a method for producing an agarobiose-containing composition that is inhibited from discoloring (yellowing) and can be stored in a colorless state for a long period of time. The process from producing agarooligosaccharides to obtaining a composition containing agarooligosaccharides involves multiple steps, and further improvements in the techniques involved in each step may lead to further improvements in productivity, for example. [Means for solving the problem]

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

[0006] The present invention solves the above problems by the solution means described below as one embodiment.

[0007] 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 hydrolysis step of hydrolyzing polysaccharides contained in the extracted red algae extract. an acid treatment step of exposing the red algae to acid prior to the extraction step; In the decomposition step, the dispersion of the red algae extract is made to have a kinematic viscosity of 5,000 to 300,000 mm at a product temperature of 70°C. 2 The polysaccharide is hydrolyzed by exposure to an acid adjusted to a range of 1 / s. 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 the red algae dispersion is exposed to an acid. It is characterized by:

[0008] According to this method, by adjusting the kinematic viscosity of the red algae extract dispersion within a predetermined range at the start of the hydrolysis reaction when the red algae extract dispersion is exposed to acid, all of the polysaccharides in the red algae extract can be homogeneously hydrolyzed throughout the hydrolysis process. Therefore, the remaining undecomposed or incompletely decomposed residue and over-decomposition are suppressed. As a result, the final yield can be improved. Furthermore, the filtration efficiency is also improved, allowing for shorter purification times and improving overall productivity. Furthermore, the improved filtration effect is thought to facilitate the removal of impurities, ultimately making it possible to obtain high-quality agaro-oligosaccharide-containing products at low cost. [Effects of the Invention]

[0009] According to the present invention, a method for producing an agarooligosaccharide-containing composition can be provided, which can improve yield and productivity. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a flow chart showing an example of a method for producing an agarooligosaccharide-containing composition according to this embodiment. [Figure 2] FIG. 2 is a chromatogram showing the results of Test 1. [Figure 3] FIG. 3 is a photograph showing the results of Test 3. DETAILED DESCRIPTION OF THE INVENTION

[0011] A method for producing an agarooligosaccharide-containing composition according to this embodiment is described below with reference to the flowchart shown in Figure 1. In this application, agarooligosaccharide is a general term for oligosaccharides of 10 or less sugars each consisting of a repeating structure of a disaccharide agarobiose unit, including agarobiose (2 sugars), agarotetraose (4 sugars), agarohexaose (6 sugars), agarooctaose (8 sugars), and agarodecaose (10 sugars). In this application, agarooligosaccharide-containing compositions are obtained by hydrolyzing a red algae extract containing agarose and / or agaropectin, which are polysaccharides having agarobiose units in their molecules, as described below. The compositions contain at least one oligosaccharide selected from agarobiose, agarotetraose, agarohexaose, agarooctaose, and agarodecaose, with the majority of the sugar composition being comprised of this oligosaccharide.

[0012] As shown in FIG. 1, the method for producing an agarooligosaccharide-containing composition according to this embodiment is broadly divided into a step of extracting a red algae extract from red algae (red algae extract extraction step S1) and a subsequent step of hydrolyzing the red algae extract to produce agarooligosaccharides (agarooligosaccharide production step S2). The agarooligosaccharide-containing composition is obtained via the agarooligosaccharide production step S2.

[0013] The red algae extract extraction process S1 includes an alkali treatment process S101, an acid treatment process S102, an extraction process S103, a filtration process S104, a cooling process S105, and a concentration process S106. Specifically, using one or more types of red algae as the raw material, the algae are exposed to alkali (alkali treatment process S101), acid (acid treatment process S102), and the resulting red algae extract is extracted with hot water (extraction process S103), filtered (filtration process S104), cooled to form a gel (cooling process S105), and the gel is then dehydrated to concentrate the extracted components (concentration process S106). All steps except for extraction process S103 are optional. Depending on whether or not cooling process S105 and concentration process S106 are performed and the implementation (method and extent), red algae extract can be obtained in various forms, such as liquid, paste, gel, dried solid, or powder. Each step is described in detail below.

[0014] The alkali treatment step S101 is a step in which red algae are exposed to alkali. Red algae contain agarose and / or agaropectin, which are polysaccharides containing agarobiose units in their molecules, and therefore can be used as a raw material for the target product, agarooligosaccharides. Specific examples include red algae belonging to the families Gelidiaceae, Pterocladiaceae, Gracilariaceae, Bangiaceae, and Ceramiaceae, and can be used simultaneously as raw materials. Freshly harvested red algae may be used, or dried red algae may be used. The alkali to which the red algae are exposed can be one or more of the following: sodium hydroxide, potassium hydroxide, calcium hydroxide, calcium oxide, and ammonium hydroxide.

[0015] Using this, in step S101, the prepared red algae can be exposed to alkali by immersing it in an alkaline solution. The red algae may be added to a pre-prepared alkaline solution, or the alkaline solution may be prepared (adjusted to the desired alkaline range) by adding alkali to a dispersion of the red algae. In step S101, the alkaline solution in which the red algae has been immersed may be exposed to alkali while being heated.

[0016] The alkali treatment in step S101 has the effect of eliminating functional groups (mainly sulfate groups of agaropectin) from the red algae polysaccharide molecules, which is thought to facilitate uniform extraction of the polysaccharide molecules that are the extracted components of the red algae. This improves extraction performance, and it is thought that the polysaccharide molecules in the extract are also uniformly hydrolyzed in the agaro-oligosaccharide production step S2, improving decomposition performance. As a result, improved yield and filtration efficiency can be achieved. However, since the amount of functional groups in the polysaccharide molecules varies slightly depending on the type and condition of the red algae used as the raw material, it is advisable to determine whether to perform step S101 and the treatment depth described below as appropriate.

[0017] The depth or effectiveness of alkaline treatment is primarily determined by three factors: alkaline strength, treatment temperature, and treatment time. The stronger the alkalinity (higher the pH), the higher the temperature, and the longer the treatment time, the deeper the treatment (the stronger the effects). Because a shallow treatment does not adequately remove functional groups, a relatively deep treatment is generally preferred. However, an excessively deep treatment can lead to the dissolution of extracted components, so a moderately deep treatment is recommended. As an example of specific treatment depth, when red algae is added to an alkaline solution adjusted to a desired concentration and exposed to the alkali, the alkaline concentration of the solution can be adjusted to a range of 0.1 to 10.0 wt%. The temperature of the treatment solution in which the red algae is immersed in the alkaline solution can be adjusted to a range of 0 to 100°C. The treatment time can be adjusted to a range of 1 to 180 minutes. More preferably, the alkaline 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 5.0±3 wt%, the treatment liquid temperature can be 90±10° C., and the treatment time can be 135 to 180 minutes. However, even if one or more of the alkali concentration, treatment liquid temperature, and treatment time conditions are not within the above ranges, by appropriately setting the other conditions, alkali treatment can be performed to a depth similar to that of the above settings or to a desired depth.

[0018] When the alkali treatment in step S101 is carried out within a range not exceeding a moderate depth, the depth or effect of the alkali treatment is expressed as the sulfate group content in the red algae extract obtained through red algae extract extraction step S1. Using this as an indicator, the lower the sulfate group content in the red algae extract, the greater the depth and effect of the alkali treatment, which is preferable in terms of the quality of the red algae extract. Therefore, although this indicator is directly linked to the depth and effect of the alkali treatment when step S101 is carried out, it is effective as an indicator of the quality of the red algae extract and therefore of the agarooligosaccharides obtained therefrom, regardless of whether or not step S101, which is optional, is carried out, and is also effective as an indicator of the quality of the agarooligosaccharide production 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 red algae extract extraction step S1 (at least extraction step S103) is preferably 1.5 mass % or less, more preferably 1.0 mass %, and even more preferably 0.7 mass % or less (Example: Test 4). The sulfate group content in this red algae extract can be quantified by gravimetric method, whereby sulfate groups are converted into sulfate ions (SO4 2- ) and measured. Details are described 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 performed, for example, by draining the treatment solution after the alkaline treatment and supplying new neutral water to remove the alkali. This water replacement can be performed once or multiple times. Alternatively, as another method of alkali removal, the alkali can be neutralized and removed by adding an acid. The purpose of the acid addition 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 different in meaning and effect from the acid treatment in step S102, etc. Note that washing and acid addition may be performed in combination as appropriate.

[0020] The acid treatment step S102 is a step of exposing the red algae to an acid, which may be one or more of 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, in step S102, the dispersion liquid in which the red algae has been dispersed can be adjusted to a desired acidity range and then exposed to acid. "Exposing to acid" means bringing the entire surface of the red algae into contact with acid; by immersing the red algae in an acid solution, the entire surface can be brought into contact with (exposed to) acid. An acid solution can be prepared (adjusted to a desired acidity range) by adding acid to the dispersion liquid in which the red algae has been dispersed, or the red algae can be added to a pre-prepared acid solution. Furthermore, in step S102, the acid solution in which the red algae has been soaked can be moderately stirred. Furthermore, although heating the acid solution in which the red algae has been soaked is not prohibited, a certain treatment effect can be achieved with an acid solution at room temperature (1 to 30°C), and treatment can also be performed with an acid solution at, for example, 10°C or below.

[0022] The acid treatment in step S102 softens the red algae cell walls and solubilizes minerals on the cell wall surface, which is believed to facilitate uniform extraction of polysaccharide molecules, which are extracted components of the red algae. This improves extraction performance, and furthermore, it is believed that the polysaccharide molecules in the extract are uniformly hydrolyzed in the agarooligosaccharide production step S2, improving decomposition performance. This results in improved yield and filtration efficiency. Furthermore, it has been shown that the agarooligosaccharides obtained by acid treatment are less susceptible to browning (yellowing) (Example: Test 3). Specifically, when the agarooligosaccharide-containing composition produced by this embodiment is heat-treated, it remains colorless and transparent, similar to before heating, or browning associated with heating is suppressed, resulting in particularly high-quality agarooligosaccharides.

[0023] The depth or effectiveness of acid treatment is primarily determined by the acid strength, with stronger acidity (lower pH) resulting in deeper treatment (stronger effectiveness). Specific examples of treatment depth include adding acid to a dispersion of red algae to prepare an acid solution (treatment solution) of a desired acidity range and exposing the resulting solution to acid. The pH of the treatment solution is preferably 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 even more preferably 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 performed, for example, by draining the post-acid treatment solution and adding new neutral water to remove the acid. This water exchange can be performed one or more times. The drainage during washing removes solubilized minerals along with the acid, which is thought to stabilize the pH in the next step, extraction step S103, and ultimately stabilize the quality of the agarooligosaccharides obtained. Alternatively, as another acid removal method, alkali can be added to neutralize and remove the acid. 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 different in meaning and effect from the alkali treatment in the previous step S101. Note that washing and alkali addition may be performed in combination as appropriate.

[0025] Extraction step S103 is a step in which red algae are immersed in hot water to extract a red algae extract, and the red algae extract is extracted with water (hot water) at 70 to 120° C. In step S103, the water in which the red algae has been dispersed (dispersion liquid) is adjusted to a neutral or nearby pH range of 5.0 to 8.0, and heated at atmospheric pressure or under appropriate pressure to adjust the temperature to 70 to 120° C., and hot water extraction is carried out for 1 to 3 hours, thereby extracting a red algae extract containing agarose and / or agaropectin.

[0026] The pH of the water can be adjusted by adding any acid and / or alkali as a buffer. The acid and alkali used in this case are not limited, and the same alkali as used in the alkali treatment step S101 and the same acid as used in the acid treatment step S102 can be used. However, the acid and alkali here are pH adjusters that adjust the progress of the extraction reaction, and are different in meaning and effect from the treatment agents used in the alkali treatment and acid treatment in the previous steps S101 and S102.

[0027] In this step S103, phosphate can be suitably added to the water (hot water) that serves as the extract. Phosphate dissolves in water and acts as a buffer to adjust the pH of the water as described above. It also chelates minerals remaining on the surface of the red algae cell walls, which is thought to facilitate the homogeneous extraction of polysaccharide molecules, which are components extracted from the red algae. This improves extraction performance, which in turn allows for more homogeneous hydrolysis of the polysaccharide molecules in the extract in the subsequent agarooligosaccharide production step S2, and is thought to improve decomposition performance. Thus, phosphate is suitable because it can buffer the pH during extraction while also acting as an extraction promoter that enhances extraction performance.

[0028] The filtration step S104 is a step of purifying the red algae extract (extract liquid) by filtration. The filtration method is not limited, and a method commonly used in the art, such as pressure filtration using a filter press, can be used. A combination of multiple filtration methods may also be used. A filter aid 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 the extract is cooled to form a gel. The red algae extract component is a so-called agar component, whose main components are agarose and / or agaropectin, and gels at temperatures below the freezing point of agar, typically 38°C or below. In this step S105, the extract is preferably cooled to 33±3°C or below.

[0030] The concentration step S106 is a step for concentrating the red algae extract components by removing water from the extract liquid, filtrate, or gelled product thereof. Concentration methods include concentration by freezing and thawing, concentration by squeezing, and concentration using an evaporator (e.g., vacuum concentration). Multiple concentration methods may be combined. Depending on the degree of concentration, red algae extract can be obtained in various forms, such as liquid, paste, gel, or dried solid, or by pulverizing the solid, powdered red algae extract can also be obtained.

[0031] Through the above red algae extract extraction step S1, a red algae extract containing agarose and / or agaropectin, which are polysaccharides having agarobiose units in the molecule, can be obtained from the raw red algae.

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

[0033] The decomposition step S207 is a step in which the dispersion of the extracted red algae extract is exposed to an acid to hydrolyze the red algae extract, i.e., the polysaccharide molecules contained in the red algae extract. In this embodiment, in this step S207, the dispersion of the red algae extract is subjected to a hydrolysis treatment to obtain a red algae extract having a kinematic viscosity of 5,000 to 300,000 mm at a product temperature of 70°C. 2 / s, and then expose to acid to cause (initiate) the hydrolysis reaction. This means that in a method in which the red algae extract is dispersed in a pre-prepared acid solution or an acid is added to (mixed with) a dispersion of the red algae extract (extract dispersion) and the extract dispersion is exposed to acid, the kinematic viscosity of the reaction solution, which is the acid solution in which the red algae extract is immersed, is adjusted to the above range. In a method in which the extract dispersion is exposed to acid by passing the mobile phase of the extract dispersion through a column using a solid acid as the stationary phase, the kinematic viscosity of the extract dispersion, which is the mobile phase, is adjusted to the above range.

[0034] The acid to which the extract is exposed can be one or more of 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 red algae extract can be immersed in a solution (acid solution) of one of these acids to expose the extract dispersion to the acid. Alternatively, a solid acid that maintains a solid form in the extract dispersion and has a cationizable functional group and hydrolyzing properties can be used. Examples of solid acids include natural minerals such as zeolite and montmorillonite, acid-treated products thereof, solidified acids obtained by impregnating and solidifying liquid acids such as sulfuric acid and phosphoric acid in alumina, silica gel, and diatomaceous earth, alumina itself, cation exchange resins, cation exchange fibers, cation exchange membranes, and mixtures thereof. In other words, both liquid and solid acids can be used. 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, the solid acid can cause the hydrolysis reaction to proceed more rapidly when it is, for example, a strong cation exchange resin rather than a weak cation exchange resin, when used in a larger amount, or at a higher operating temperature.

[0035] The red algae extract obtained through the red algae extract extraction step S1 can also be in either a liquid or solid form. A liquid red algae extract is a dispersion of the red algae extract itself. On the other hand, for a solid red algae extract, for example, a powder or a dried solid can be re-dispersed in a liquid to prepare an extract dispersion, and a paste can also be prepared as an extract dispersion by adding an appropriate liquid. Furthermore, a gel can be re-solized by heating, and an extract dispersion can be prepared by adding appropriate water.

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

[0037] In this embodiment, the dispersion of the red algae extract has a kinematic viscosity of 5000 to 300,000 mm at a product temperature of 70°C. 2The dilution rate is adjusted to within the range of / s and exposed to acid to initiate the hydrolysis reaction of the polysaccharide molecules contained in the red algae extract. Although it is generally known that stirring a reaction system promotes chemical reactions, when a red algae extract is exposed to acid for hydrolysis, the stirrability of the reaction solution naturally improves as the reaction progresses and the polysaccharides are decomposed. Therefore, parameters related to the stirrability of the reaction solution have not been of interest in the technical field to which the present invention pertains. However, the inventors have hypothesized that poor stirrability of the extract dispersion would result in a non-uniform reaction throughout the extract, leading to a non-uniform molecular weight distribution of intermediates, resulting in the presence of undecomposed or incompletely decomposed residues or over-decomposition, resulting in a reduced final yield. Recognizing the particular importance of stirrability in this technical field, the inventors focused on parameters related to this. Based on this, through extensive research, they discovered that the dispersion concentration of the extract is of a certain importance. Furthermore, they discovered that the kinematic viscosity of the extract dispersion at the initiation point of the hydrolysis reaction when the extract dispersion is exposed to acid significantly affects the final yield, leading to the present invention.

[0038] That is, in the present invention, the kinematic viscosity of the extract dispersion at the starting point of the hydrolysis reaction at a product temperature of 70°C is 5000 to 300000 mm 2 By adjusting the kinematic viscosity to within the range of / s, it is possible to homogeneously hydrolyze the entire red algae extract through the decomposition step S207. During the process leading to the invention, the kinematic viscosity was kept within a predetermined range to improve the stirrability of the reaction solution. However, it was discovered that setting the kinematic viscosity too low makes it difficult for the red algae extract to disintegrate if it forms clumps, thereby reducing dispersibility and resulting in an inhomogeneous reaction. As a result, the invention was realized as the above-mentioned optimal range, which improves stirrability by keeping the kinematic viscosity of the extract dispersion below a certain level, while maintaining a certain level of dispersibility of the extract, thereby improving final yield and productivity. Meeting this requirement improves final yield and filtration efficiency, enabling purification in a shorter time and improving overall productivity. Furthermore, improved filtration efficiency is believed to facilitate the removal of impurities, ultimately enabling the production of high-quality agarooligosaccharide-containing products at low cost.

[0039] Furthermore, during the process leading to the invention, it was discovered that while the kinematic viscosity is essentially adjusted by the dispersion concentration of the red algae extract, when attempting to adjust the dispersion concentration itself as a parameter related to the stirrability of the reaction solution, the physical properties (stirrability) of the extract dispersion may vary depending on the type of red algae, even at the same dispersion concentration, making it difficult to uniformly specify an optimal dispersion concentration, and in some cases, optimal stirrability may not be achieved. On the other hand, if the dispersion concentration of the extract is too low, the amount of extract used for hydrolysis decreases, resulting in reduced productivity, so it is preferable to set a lower limit for the dispersion concentration of the extract. In this regard, in addition to the above-mentioned kinematic viscosity range, it is more preferable to adjust the dispersion concentration of the red algae extract (the concentration of solid red algae extract added to the reaction solution) to 5 wt% or more, in other words, to adjust the dispersion concentration of the red algae extract dispersed at a concentration of 5 wt% or more so that it falls within the above-mentioned kinematic viscosity range, and then expose it to acid.

[0040] As mentioned above, the kinetic viscosity of the extract dispersion is basically adjusted by the dispersion concentration of the red algae extract, etc. Therefore, although it is assumed that setting the kinetic viscosity too low will reduce the extract content in the extract dispersion, ultimately resulting in a reduced yield, in fact, as shown in the Examples described below, setting the kinetic viscosity too low tends to reduce not only the yield but also the filtration efficiency (Example: Test 2). This suggests that a decrease in the kinetic viscosity causes unpredictable effects on the hydrolysis reaction itself. And, as mentioned above, it has been confirmed that these effects cause problems with the dispersibility of the extract. The kinetic viscosity range according to the present invention is an optimal range discovered through extensive trial and error despite the existence of such unpredictable effects.

[0041] In the examples described below, the extract dispersion was adjusted to have a kinematic viscosity within the above range and then exposed to an acid for hydrolysis, 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, it can be seen that the kinematic viscosity range is 5000 to 300,000 mm 2 / s is 5000~200000mm 2 / s range is more preferable, and 5000 to 120000 mm 2 / s is more preferable, 5000 to 60000 mm 2 / s is more preferable, 5000 to 30000 mm 2 The kinematic viscosity in this application is a value measured and calculated using a single-cylindrical rotational viscometer, a B-type viscometer (TV-10, manufactured by Toki Sangyo Co., Ltd.), at a product temperature of 70°C using a No. M4 spindle in accordance with the method described in JIS Z8803:2011. The rotation speed of the spindle is specifically shown in the examples.

[0042] In step S207, the acid hydrolysis of the red algae extract containing agarose and / or agaropectin can be carried out according to conventional methods (e.g., Patent Documents 1 and 2). The type and amount (concentration) of acid, as well as the pH of the reaction solution, reaction temperature, and reaction time can be appropriately set within ranges that achieve the objective of decomposing the polysaccharides (agarose and / or agaropectin) in the red algae extract into agarooligosaccharides. Therefore, the hydrolysis reaction can be carried out by adjusting the kinematic viscosity of the extract dispersion at the start of the hydrolysis reaction to the range described in Patent Documents 1 and 2, while setting other conditions within the ranges described in Patent Documents 1 and 2, for example. 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 1.0 to 5.0, more preferably 1.0 to 4.0, and even more preferably 1.0 to 3.0. Note that this pH refers to the pH at the time of preparation of the reaction solution (at the start of the reaction). The reaction solution is, as described above, the acid solution in which the red algae extract is immersed. The temperature of the reaction solution may be adjusted to a range of 10 to 120° C., more preferably a range of 50 to 100° C., more preferably a range of 80 to 100° C., and even more preferably a range of 90 to 100° C. The reaction time may be adjusted to a range of 30 minutes to 12 hours, more preferably a range of 1 to 6 hours.

[0043] Through the hydrolysis reaction, the α(1,3) glycosidic bond between D-galactopyranose and 3,6-anhydro-L-galactopyranose in the polysaccharides agarose and agaropectin contained in the red algae extract is cleaved, resulting in the decomposition into the oligosaccharides agarobiose, agarotetraose, agarohexaose, agarooctaose, and agarodecaose, called agarooligosaccharides. In this way, agarooligosaccharides can be produced from red algae, resulting in an agarooligosaccharide-containing composition. The content of agarooligosaccharides can be analyzed by HPLC or other methods (Example: Test 1).

[0044] After hydrolysis, the acid is removed from the decomposition liquid after hydrolysis, if necessary. Liquid acid can be removed by neutralizing the acid by adding an 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 cut-off membrane, or the like. Multiple removal methods may be combined. Furthermore, the decomposition liquid is cooled to about room temperature, if necessary.

[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 methods commonly used in the art, such as removal of impurities using activated carbon or hollow fiber membranes, or pressure filtration using a filter press, can be used. Among these, for example, activated carbon treatment can be used to adsorb and remove low-molecular-weight impurities. A combination of purification methods may also be used. A filter aid such as diatomaceous earth may also be used.

[0046] According to this embodiment, adjusting the kinematic viscosity of the red algae extract dispersion in the preceding step S207 to uniformly hydrolyze all of the polysaccharides in the extract improves the purification efficiency in the main step S208. Specifically, by suppressing the remaining undecomposed or incompletely decomposed residues, which are high molecular weight and relatively viscous, clogging of the filter material (filtering agent) is suppressed, resulting in improved filtration efficiency and shorter purification times. Furthermore, improved filtration efficiency is believed to further accelerate the removal of impurities, ultimately enabling the production of high-quality agaro-oligosaccharide-containing products at low cost. Furthermore, by performing the alkali treatment step S101 and / or the acid treatment step S102, it is possible to further improve purification efficiency and suppress browning, thereby obtaining even higher-quality agaro-oligosaccharide-containing products (Examples: Tests 2-5).

[0047] The drying step S209 is a step of drying the decomposition solution or the purified solution thereof. The water is removed by a conventional method in the art, such as freeze-drying, to obtain a powdered agarooligosaccharide-containing composition.

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

[0049] [Test 1] One kg of dried Gracilaria was added to 20 kg of 5 wt% sodium hydroxide (NaOH) solution and soaked for 2 hours while heating to 90°C. The NaOH solution was drained and the Gracilaria was thoroughly washed with water to remove the alkali. This Gracilaria was added to 20 kg of water, and a sulfuric acid (H2SO4) solution was added to adjust the pH to 2.0. After the Gracilaria was acclimated to the acid, the H2SO4 solution was drained and 20 kg of fresh water was added. Five grams of dibasic sodium phosphate (Na2HPO4) was added to adjust the pH to 7.0, and extraction was carried out for 2 hours while heating to 97°C. The extract was then filtered, and the filtrate was cooled to room temperature, compressed and concentrated using a filter press, dried with hot air at 90°C, and pulverized to obtain a powdered Gracilaria extract. The resulting extract had a kinematic viscosity of 30,000 mm at a product temperature of 70°C. 2 The extract was dispersed in a 0.1 wt% H2SO4 solution to a concentration of 1 / s. The extract dispersion concentration in the extract dispersion (reaction liquid) was 5 wt% or higher. The extract dispersion (reaction liquid) 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 liquid to adsorb low molecular weight components. The liquid was then filtered and freeze-dried to obtain a powder.

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

[0051] The obtained powder was dissolved in distilled water and analyzed by liquid chromatography using the following column under the following analytical conditions, following the usual procedures for sugar composition analysis. Column: TSKgel G2500PW XL Inner diameter 7.8mm x length 300mm Guard column: TSKgel guardgel (Both 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] The resulting chromatogram is shown in Figure 2. Peak 1 (retention time 40.8 minutes) in Figure 2 represents a disaccharide, peak 2 (retention time 38.4 minutes) represents a tetrasaccharide, peak 3 (retention time 36.8 minutes) represents a hexasaccharide, and peak 4 (retention time 35.8 minutes) represents an octasaccharide. It is well known that Gracilaria extract components are so-called agar components, primarily composed of agarose and agaropectin. Therefore, it is almost certain that the disaccharide detected here is an oligosaccharide primarily composed of agarobiose, the tetrasaccharide, agarotetraose, the hexasaccharide, agarohexaose, and the octasaccharide, agarooctaose. Therefore, the obtained powder was confirmed to be an agarooligosaccharide-containing composition.

[0053] [Test 2] One kilogram of dried Gracilaria was added to 20 kg of 5 wt% sodium hydroxide (NaOH) solution and heated to 90°C for 2 hours. The NaOH solution was drained and the Gracilaria was thoroughly washed with water to remove the alkali. The Gracilaria was added to 20 kg of water, and a sulfuric acid (H2SO4) solution was added to adjust the pH to 2.0. After the Gracilaria was acclimated to the acid, the H2SO4 solution was drained and 20 kg of fresh water was added. Five grams of dibasic sodium phosphate (Na2HPO4) was added to adjust the pH to 7.0, and the mixture was heated to 97°C for 2 hours for extraction. The extract was then filtered, cooled to room temperature, compressed and concentrated using a filter press, dried with hot air at 90°C, and pulverized to obtain a powdered Gracilaria extract. The resulting extract was dispersed in 0.1 wt% H2SO4 solution so that the kinematic viscosity at 70°C was the value shown in Table 1. The dispersion concentration of the extract in the extract dispersion (reaction liquid) was higher as the kinematic viscosity increased and lower as the kinematic viscosity decreased, but was 5 wt% or higher in all cases. The extract dispersion (reaction liquid) 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 liquid to adsorb low molecular weight impurities. The liquid was then filtered and freeze-dried to obtain an agarooligosaccharide-containing composition.

[0054] (filtration efficiency) For the Examples and Comparative Examples in which the dispersion of Gracilaria extract was adjusted to each kinematic viscosity and subjected to acid hydrolysis, after cooling, activated carbon treatment and subsequent filtration were carried out as described above. The filtration efficiency was measured using an ADVANTEC vacuum filtration unit to measure the time [seconds] required for 100 mL of the decomposition liquid sample to pass through a membrane filter with a pore size of 0.2 μm and a diameter of 47 mm, and evaluated according to the following criteria. Less than 60 seconds ◎ Between 60 and 180 seconds: 180 seconds or more but less than 500 seconds △ 500 seconds or more ×

[0055] (yield) The mass of the obtained agarooligosaccharide-containing composition was measured according to the formula below, and its moisture content was set to 5 wt%. The dry mass obtained by subtracting the moisture from the measured mass was calculated as a mass percentage relative to the mass (1 kg) of the raw material red algae, Gracilaria verrucosa. The yield [%] was evaluated according to the following criteria. Yield [%] = [(Agarooligosaccharide-containing composition mass × 0.95) / Gracilaria mass] × 100 9.00% or more ◎ 8.00% or more but less than 9.00% 〇 6.00% or more but less than 8.00% △ Less than 6.00% ×

[0056] The results are shown in Table 1. The spindle rotation speeds used for adjusting (measuring) the kinematic viscosity are also shown.

[0057] [Table 1]

[0058] As shown in Table 1, the dynamic viscosity of the dispersion of Gracilaria extract was set to 5,000 to 300,000 mm 2 In Examples 1 to 6, in which the kinematic viscosity was adjusted to 5000 mm / s and exposed to acid for reaction, the yield was improved compared to Comparative Examples 1 and 2, in which the kinematic viscosity was outside the range. 2 / s or more, it is possible to achieve a lower 2 / s) (Example 1), and the kinematic viscosity is improved to 300,000 mm 2 / s or less, the higher Comparative Example 2 (600,000 mm 2 / s) (Example 6), and the kinematic viscosity is improved to 5,000 to 300,000 mm 2 / s, the filtration efficiency tended to improve.

[0059] From the results of this test 2, the kinematic viscosity of the extract dispersion at the start of the hydrolysis reaction when the extract dispersion is exposed to acid is set to 5000 to 300,000 mm 2It is preferable to adjust the range to 5000 to 200,000 mm / s. 2 / s range is more preferable, and 5000 to 120000 mm 2 / s range is more preferable, 5000 to 60000 mm 2 / s range is more preferable, and 5000 to 30000 mm 2 / s range is more preferable.

[0060] [Test 3] One kilogram of dried Gracilaria was added to 20 kg of a 5 wt% sodium hydroxide (NaOH) solution and soaked for 2 hours while heating to 90°C. The NaOH solution was drained, and the Gracilaria was thoroughly washed with water to remove the alkali. This Gracilaria was added to 20 kg of water, and a sulfuric acid (H2SO4) solution was added to adjust the pH to the values ​​shown in Table 2. After the Gracilaria was acclimated to the acid, the H2SO4 solution was drained, and 20 kg of fresh water was added. Five grams of dibasic sodium phosphate (Na2HPO4) was added, adjusting the pH to 7.0, and extraction was carried out for 2 hours while heating to 97°C. The extract was then filtered, cooled to room temperature, compressed and concentrated using a filter press, dried with hot air at 90°C, and pulverized to obtain a powdered Gracilaria extract. The resulting extract had a kinematic viscosity of 30,000 mm at a product temperature of 70°C. 2 The extract was dispersed in a 0.1 wt% H2SO4 solution to a concentration of 1 / s. The concentration of the extract in the extract dispersion (reaction solution) in each example was 5 wt% or higher. The extract dispersion (reaction solution) was heated to 90°C for 3 hours and 30 minutes, and then cooled to room temperature. 400 g of activated carbon was added to this decomposition solution to adsorb low-molecular-weight impurities. This solution was then filtered and freeze-dried to obtain an agarooligosaccharide-containing composition. In contrast to the examples, in Reference Example 1, Gracilaria verrucosa was exposed to alkali, and after removing the alkali, 20 kg of water was simply added without acid treatment (pH: 7.0). Subsequently, sodium diphosphate was added and extraction was performed as in the examples, and the resulting extract was hydrolyzed to obtain an agarooligosaccharide-containing composition.

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

[0062] (resistance 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. Colorless and transparent (same as before heating) Slightly yellowish ○ Yellowish △ The results are shown in Table 2 and Figure 3. Figure 3 is a photograph of the aqueous solutions of the agarooligosaccharide compositions of the examples subjected to the above color evaluation.

[0063] [Table 2]

[0064] As shown in Table 2, Examples 7 to 13, in which Gracilaria gracilaria was exposed to acid before hot water extraction, achieved stable yields and filtration efficiencies of at least 7.39% and 153 seconds, respectively. The results generally indicated that the lower the pH and the deeper the acid treatment, the greater the improvement in yield and filtration efficiency. Furthermore, as shown in Figure 3, the color evaluation for resistance to browning showed a tendency for the yellow color to fade and become more transparent with a lower pH and deeper acid treatment, demonstrating the effectiveness of acid treatment in inhibiting browning. The results of this experiment 3 suggest that acid treatment is preferable for exposing red algae to acid before hot water extraction. In this case, the pH of the red algae dispersion is preferably adjusted to an acidic range of 1.5 to 5.0 before exposure, with a pH range of 1.5 to 4.0 being more preferable, a pH range of 1.5 to 3.0 being even more preferable, and a pH range of 2.0 to 3.0 being even more preferable.

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

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

[0067] (Sulfate group content) The sulfate group content of Gracilaria extract was measured by a conventional gravimetric method. Powdered Gracilaria extract was dissolved in boiling pure water, 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: sulfate ion (SO4 2- This was divided by the mass of the powdered Gracilaria extract (dry mass of the Gracilaria extract) measured in advance, and converted into 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 gracilis was exposed to alkali before hot water extraction (before acid treatment), achieved a yield of at least 8.37% and a filtration efficiency of 301 seconds, demonstrating stable yield and filtration efficiency. The longer and deeper the alkali treatment, the greater the tendency for yield and filtration efficiency to improve. Furthermore, the longer and deeper the alkali treatment, the lower the sulfate group content of the extract. A correlation was observed between the depth of the alkali treatment, which has the effect of eliminating functional groups from the red algae polysaccharide molecules, and the sulfate group content of the extract. Based on the results of this experiment 4, it is preferable to expose the red algae to alkali before hot water extraction. In this case, the exposure time is preferably 45 minutes or longer (45-180 minutes), more preferably 90 minutes or longer (90-180 minutes), and even more preferably 135 minutes or longer (135-180 minutes). Furthermore, in the method for producing agarooligosaccharides by extracting red algae with hot water and hydrolyzing the extract, it is preferable that the sulfate group content of the dry mass of the red algae extract obtained by hot water extraction is 1.5% by mass or less, more preferably 1.0% by mass or less, and even more preferably 0.7% by mass or less.

[0070] [Test 5] One kilogram of dried Tengusa was added to 20 kg of 5 wt% sodium hydroxide (NaOH) solution and immersed for 2 hours while heating to 90°C. The NaOH solution was drained and the solution was thoroughly washed with water to remove the alkali. This Tengusa was added to 20 kg of water, and a sulfuric acid (H2SO4) solution was added to adjust the pH to 2.0. After the Tengusa had acclimated to the acid, the H2SO4 solution was drained and 20 kg of fresh water was added. Five grams of dibasic sodium phosphate (Na2HPO4) was added to adjust the pH to 7.5, and the mixture was extracted for 100 minutes while heating to 97°C. The extract was then filtered, cooled to room temperature, compressed and concentrated using a filter press, dried with hot air at 90°C, and pulverized to obtain a powdered Tengusa extract. The resulting extract was analyzed to determine the kinematic viscosity of 30,000 mm at a product temperature of 70°C. 2 The extract was dispersed in a 0.1 wt% H2SO4 solution to a concentration of 1 / s, and the concentration of the extract in the resulting extract dispersion (reaction liquid) was 5 wt% or higher. The extract dispersion (reaction liquid) 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 liquid to adsorb low molecular weight components. The liquid was then filtered and freeze-dried to obtain a powder.

[0071] As in Test 1, the obtained powder was dissolved in distilled water and analyzed by liquid chromatography. As in Test 1, peaks representing disaccharides, tetrasaccharides, hexasaccharides, and octasaccharides were detected, 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 Tengusa is used as a raw material. Furthermore, as in Test 2, the filtration efficiency and yield were measured, calculated, and evaluated. The results are shown in Table 4.

[0072] [Table 4]

[0073] As shown in Table 4, the filtration efficiency and yield were good even when Tengusa was used as the raw material. It can be said that the method for producing agarooligosaccharides according to the present invention is generally applicable to any red algae containing 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. an extraction step of immersing red algae in water at 70 to 120°C to extract a red algae extract; a decomposition step of hydrolyzing polysaccharides contained in the extracted red algae extract; an acid treatment step of exposing the red algae to an acid before the extraction step; In the decomposition step, the dispersion of the red algae extract is dissolved in a solution having a kinematic viscosity of 5,000 to 300,000 mm at a product temperature of 70°C. ２ and exposing the polysaccharide to an acid in a range of 0.1 to 1.5 wt % by weight to hydrolyze the polysaccharide. 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 the dispersion is exposed to an acid. A method for producing an agarooligosaccharide-containing composition, comprising:

2. In the decomposition step, the dispersion in which the red algae extract is dispersed at a concentration of 5 wt % or more is adjusted to have a kinematic viscosity within the range, and is then exposed to an acid.

2. The method for producing the agarooligosaccharide-containing composition according to claim 1,

3. The content of sulfate groups in the dry mass of the red algae extract obtained through the extraction step is 1.5% by mass or less.

3. The method for producing the agarooligosaccharide-containing composition according to claim 1 or 2, characterized by:

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