How to produce shallot fructan

Abstract

To provide a method of manufacturing scallion fructan capable of being applied not only to scallion but also salt storage residue and pickled juice.SOLUTION: A method for producing scallion fructan, which comprises using a solution containing scallion fructan as a raw material and purifying scallion fructan through a membrane separation process in which low-molecular components are separated using a membrane to obtain a scallion fructan solution. This makes it possible to obtain highly purified scallion fructan solutions or scallion fructan powder as raw materials for various scallion fructan-containing solutions. In addition, by using salt storage residue and pickled juice as raw materials, it is possible to greatly reduce a salt content in the salt storage residue, etc., making it easier to treat waste and making it possible to use the salt storage residue effectively as fertilizer.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a method for producing rakkyo fructan. More specifically, the present invention relates to a method for producing rakkyo fructan that can utilize residues generated during the production of pickled rakkyo products. [Background technology]

[0002] Rakkyo is a vegetable rich in dietary fiber, and much of it is processed and sold as pickled products.

[0003] When rakkyo is processed into pickled products, it undergoes a process called salting (Figure 9, c). In other words, pickled radishes harvested around June or July are washed and then soaked in a pickling liquid containing salt and resistant lactic acid bacteria for preservation. This not only preserves the radishes, but also enhances their umami flavor by breaking down the radish's protein through fermentation, producing free amino acids, and the high salt concentration eliminates harmful bacteria. By processing these salted pickled radishes into pickled products at the appropriate time, it is possible to provide a stable supply of products throughout the year.

[0004] When salted radishes are processed into pickled products, a large amount of unnecessary parts (salting residue), such as the skin and roots, that cannot be used as products, are generated (Figure 9, d). This salted residue has a relatively high salt concentration of about 5 to 13%, and cannot be disposed of as is. Therefore, the current situation is that it is mixed with other residues with a low salt concentration or desalted to reduce the salt concentration before disposal. Furthermore, a large amount of pickling water is generated during salting (Figure 9, e). Because this pickling water also has an extremely high salt concentration, it must be diluted with a large amount of water or desalted to reduce the salt concentration before processing. Thus, when processing shallots into pickled products, it is essential to dispose of the salted residue and pickling liquid, and currently a large amount of cost is spent on disposal.

[0005] On the other hand, it is known that rakkyo is rich in water-soluble polysaccharides called fructans (Patent Document 1). Fructans are compounds formed by polymerizing fructose and are known to have useful effects such as suppressing blood sugar levels and improving bowel movements. For this reason, technologies related to health foods using fructans (Patent Documents 2 and 3) and methods for producing fructans (Patent Documents 4 and 5) have been disclosed. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2010-193841 [Patent Document 2] Japanese Patent Application Publication No. 2019-146533 [Patent Document 3] Patent Publication No. 2021-168708 [Patent Document 4] Japanese Patent Application Laid-Open No. 2012-193256 [Patent Document 5] Japanese Patent Application Publication No. 10-158306 DISCLOSURE OF THE INVENTION [Problem to be solved by the invention]

[0007] Patent Documents 4 and 5 disclose techniques for producing non-inulin-type fructan extracts, and specifically disclose techniques using shallots as a raw material. These prior art techniques are useful in that they can extract shallot fructan.

[0008] However, the inventors believe that the prior art has several problems. The first issue is that the series of steps in the prior art is difficult to apply to salted residues. In other words, when the prior art is used with salted residues as a raw material, a large amount of salt is mixed into the final fructan. Although it is not without utility as a salt-containing fructan, the prior art is not sufficient when pure fructan is required. Similarly, if the prior art is applied to pickling liquid, similar problems will arise.

[0009] The second issue is that the prior art involves heat treatment. Fructans are not necessarily stable to heat, so there is concern that the properties of fructans may change due to heat treatment. In addition, after heating, a large amount of extract must be left overnight to cool, which takes time, and therefore the prior art has issues in terms of time efficiency.

[0010] Against the background of the above circumstances, the objective of this invention is to develop a method for producing rakkyo fructan that can be applied not only to rakkyo but also to salted residues and pickling liquid. [Means for solving the problem]

[0011] As a result of extensive research, the inventors discovered that usable fructans are contained not only in the raw radish material, but also in the salted residue and pickling liquid. From this, we came up with a method for producing rakkyo fructan that uses not only rakkyo but also salted residue and pickling liquid as raw materials and performs membrane separation, making it possible to purify rakkyo fructan, and completed the invention.

[0012] The present invention comprises the following configurations. [1] A method for producing rakkyo fructan, characterized by using a rakkyo fructan-containing solution as a raw material, purifying the rakkyo fructan through a membrane separation process that separates low molecular weight components using a membrane, and obtaining a rakkyo fructan solution.

[0013] [2] Furthermore, the method for producing rakkyo fructan described in [1] further comprises a concentration step in which the solution containing rakkyo fructan is concentrated after membrane separation to obtain a concentrated rakkyo fructan solution. [3] Regarding the solution containing rakkyo fructan or the concentrated solution of rakkyo fructan, After the drying and powdering process using either freeze-drying, spray-drying, or vacuum drying, A method for producing rakkyo fructan as described in [2], which obtains rakkyo fructan powder.

[0014] [4] A method for producing radish fructan described in any of [1] to [3], wherein the membrane separation is a membrane that separates low molecular weight components of 10.0 kDa or less.

[0015] [5] A method for producing radish fructan as described in [1], in which the pH is adjusted to 9.0 to 11.5, a pH adjustment process is performed to perform deproteinization, and then a membrane separation process is performed.

[0016] [6] The solution containing rakkyo fructan is The method for producing rakkyo fructan described in [1] is the pickling liquid that is produced when salting rakkyo. [7] Pickled radish or salted pickled radish residue, or any one or more of these as the raw material for pickled radish, A method for producing rakkyo fructan as described in [1], in which the rakkyo raw material is subjected to a compression extraction process, and the compressed extract obtained is used as a rakkyo fructan-containing solution. [8] A method for producing rakkyo fructan as described in [7], in which the pickling liquid generated when salting rakkyo is further combined with a squeezed extract containing rakkyo fructan to obtain a raw material for the rakkyo fructan-containing solution. [9] A method for producing fructan as described in [7], in which the squeeze-extraction process is carried out after a crushing process in which fresh pickled radishes or salted pickled radish residue is crushed before the squeeze-extraction process.

[0017]

[10] A method for producing radish fructan as described in any one of [1] or [2], [5] to [9], in which the steps other than the drying step are carried out at 10 to 50°C. [Effects of the Invention]

[0018] The present invention makes it possible to provide a method for producing rakkyo fructan that can be applied not only to rakkyo but also to salted residues and pickling liquid. [Brief explanation of the drawings]

[0019] [Figure 1] A diagram showing a flowchart of a method for producing rakkyo fructan. [Figure 2] A diagram showing a flowchart of a method for producing rakkyo fructan. [Figure 3] A diagram showing a flowchart of a method for producing rakkyo fructan. [Figure 4] A diagram showing a flowchart of a method for producing rakkyo fructan. [Figure 5] A diagram showing a flowchart of a method for producing rakkyo fructan. [Figure 6] A diagram showing a flowchart of a method for producing rakkyo fructan. [Figure 7] A diagram showing a flowchart of a method for producing rakkyo fructan. [Figure 8] A graph showing the results of gel filtration HPLC analysis of rakkyo fructans. [Figure 9] A diagram showing examples of the appearance of rakkyo at each stage. DETAILED DESCRIPTION OF THE INVENTION

[0020] The present invention will be explained below. In the following, for the sake of convenience, terms will be used in the following senses to distinguish the state of the shallots. [Rakkyo vegetables, Figure 9a, Figure 9b] Rakkyo in almost its original state, i.e., harvested rakkyo that have been washed to remove dirt and other impurities. [Salted residue, Figure 9c] After salting fresh scallions, they are removed and the unnecessary parts are removed in order to use the fruit as a product. This usually includes excess skin and roots. [Pickling liquid, Figure 9e] A soup containing salt used when salting fresh pickled radishes. [Rakkyo products, Figure 9f] After salting the fresh radishes, unnecessary parts are removed and the product is processed through a series of steps, resulting in a product consisting of the fruit and seasoning liquid. [Rakkyo raw materials] This refers to the combination of pickled radishes, salted residue, and other tangible parts of pickled radishes.

[0021] The method for producing rakkyo fructan of the present invention is characterized by using a rakkyo fructan-containing solution as a raw material, purifying the rakkyo fructan through a membrane separation process in which low molecular weight components are separated using a membrane, and obtaining a rakkyo fructan solution. This makes it possible to obtain a highly purified rakkyo fructan solution or rakkyo fructan powder as a raw material for various rakkyo fructan-containing solutions. In addition, by using salting residues and pickling juice as raw materials, it is possible to significantly reduce the salt content contained in the salting residues, etc., which has the effect of making waste disposal easier and enabling effective use as fertilizer. In addition, since it is possible to remove low molecular weight components such as fructose and free amino acids, it has the effect of preventing discoloration (browning due to the Maillard reaction) when fructan is powdered.

[0022] In the present invention, the following may be used as the raw material for the radish fructan-containing solution. (1) A squeezed extract obtained by squeezing and extracting fresh shallots or salted residues with the addition of a solvent as necessary. Or, a product derived from this that has undergone pH adjustment or solid-liquid separation. (2) Pickling juice, or products derived from this that have undergone pH adjustment or solid-liquid separation. (3) Squeezed extract obtained by adding a solvent to a rakkyo product as necessary and extracting it by squeezing, etc. Or, a product derived from this and subjected to pH adjustment, solid-liquid separation, etc.

[0023] Using Figure 1 as an example, we will explain the method for producing rakkyo fructan using rakkyo raw materials such as fresh rakkyo, salted residue, and rakkyo products. FIG. 1 is a flow chart showing an example of the method for producing rakkyo fructan of the present invention, which is the method involving the greatest number of steps.

[0024] The washing step (S1) is an optional step in which the rakkyo raw material is washed to make it suitable for the subsequent steps. The washing process involves, for example, removing dirt adhering to the pickled radish, washing it with water, or washing away the pickling liquid adhering to the salted residue with water.

[0025] The crushing step (S2) is an optional step in which the raw radish material is crushed to a certain size to make it easier to press. The crushing step does not need to be particularly limited as long as it is possible to crush the raw radish material, and crushing can be carried out by various methods. The grinding process typically involves grinding the shallot raw material to a certain size using a grinder or homogenizer. Alternatively, the shallot raw material may be finely chopped using a slicer or the like. It is preferable that the raw material crushing process be performed in conjunction with the compression extraction process described below. That is, it is preferable that the raw rakkyo material is subjected to compression extraction either directly or with the addition of a solvent using equipment used for compression extraction, and that crushing and compression extraction be performed substantially simultaneously. This has the effect of efficiently obtaining a fructan-containing solution raw material from the raw rakkyo material.

[0026] The compression extraction step (S3) is a step of extracting liquid components from the rakkyo raw material or crushed rakkyo raw material by compression. The compression extraction step does not need to be particularly limited as long as it is possible to extract such liquid components, and compression extraction can be performed by various methods. The compression extraction step is typically carried out using a juicer or a screw press. Furthermore, when performing compression extraction, compression extraction may be performed with a solvent added as necessary, or the extraction may be diluted with a solvent after compression extraction. In such cases, an aqueous solvent may be used as the solvent, and typically, water may be used. Alternatively, an organic solvent may be used, or a mixed solvent of an organic solvent and water may be used. As the organic solvent, for example, ethanol may be used, or a mixed solvent of ethanol and water may be used.

[0027] By using S1 to S3, a fructan-containing solution raw material can be obtained from solid matter such as shallots and salted residues. The obtained fructan-containing solution raw material may be purified directly by a membrane separation process, or may be purified through a pH adjustment process and a solid-liquid separation process. In addition, the fructan-containing solution raw material obtained from the radish raw material may be combined with the pickling liquid to form the raw material liquid, which may be used in the subsequent steps.

[0028] The pH adjustment step (S4) is an optional step in which the pH of the fructan-containing solution raw material is adjusted to remove proteins in the solution as precipitates, and the pH is adjusted to 9.0 to 12.0, more preferably 9.0 to 11.5, even more preferably 9.5 to 11.5, particularly preferably 9.5 to 11.0, and most preferably 9.5 to 10.5. The pH adjustment step does not need to be particularly limited as long as such pH adjustment and protein precipitation removal are possible, and can be performed by various methods. In the pH adjustment step, the pH may typically be adjusted using an alkaline solution. The alkaline solution used does not need to be particularly limited, and various alkaline solutions can be used, such as sodium hydroxide solution, calcium hydroxide solution, magnesium hydroxide solution, etc., and most preferably, calcium hydroxide solution can be used.

[0029] The solid-liquid separation step (S5) is an optional step for removing solid components from the raw fructan-containing solution or the pH-adjusted fructan-containing solution, i.e., for efficient membrane separation, the solid components are removed to prevent clogging of the membrane. The solid-liquid separation step does not need to be particularly limited as long as it is possible to remove solid components from the liquid, and can be carried out by various methods. For example, solid-liquid separation can be carried out by separation by centrifugal sedimentation (centrifugal sedimentation separation step) or filter filtration (filter filtration separation step).

[0030] The membrane separation step (S6) involves membrane separation of the fructan-containing solution raw material or the pH-adjusted fructan-containing solution to remove low-molecular-weight components other than fructan. This process makes it possible to remove salt (sodium chloride) from the solution, enabling the use of fructan-containing solution raw materials derived from salting residues or pickling juice. In addition, it makes it possible to remove fructose and free amino acids from the raw material solution, improving the purity of the final product and the quality of the crystal shape. Furthermore, it has the effect of preventing discoloration of fructan crystals (browning due to the Maillard reaction) caused by the reaction of fructose with free amino acids. The membrane separation process does not need to be particularly limited as long as it is possible to remove such low molecular weight components, and various membrane separation methods can be used, including techniques using dialysis membranes and ultrafiltration membranes. The membrane separation step typically involves removing low-molecular-weight components using a cellulose-based dialysis membrane. Since it is particularly important to remove salt (molecular weight 58.5), fructose (molecular weight 180), free amino acids (molecular weight 75 to 204), and low-molecular-weight peptides, a dialysis membrane capable of removing components with a molecular weight of 500 or less (0.5 kDa or less), more preferably 1,000 or less (1.0 kDa or less), should be selected. Furthermore, depending on the reliability of membrane separation and the adjustment of the fructan molecular weight, a membrane with a molecular weight of 5,000 or less (5.0 kDa or less), 10,000 or less (10.0 kDa or less), or 15,000 or less (15.0 kDa or less) can also be used.

[0031] The concentration step (S7) is an optional step in which the solution obtained by the membrane separation step is concentrated. The concentration step does not need to be particularly limited as long as it is possible to concentrate the raw material liquid after the membrane separation step, and can be performed by various methods. The concentration step may typically be performed by membrane concentration using a reverse osmosis membrane or by concentration by vacuum distillation. Furthermore, the concentrated solution itself can be used as a fructan-containing liquid, either as a finished product or as a semi-finished product.

[0032] The powdering step (S8) is an optional step in which the solution obtained after the membrane separation step or the concentration step is powdered, thereby obtaining the final fructan powder (Figure 9, g). The powdering step does not need to be particularly limited as long as it is possible to powder the fructan, and can be performed by various methods. The powdering step may be carried out using a drying method such as lyophilization, freeze-drying, or vacuum drying. Preferably, lyophilization or freeze-drying can be used.

[0033] In the present invention, no special heating is required in any of the steps, and the steps can be carried out at room temperature, which has the effect of preventing thermal decomposition of fructans and improving the purity and quality of the obtained fructans. In either step, the steps can usually be carried out at any reasonable room temperature, typically 10 to 50°C, preferably 10 to 40°C, more preferably 10 to 35°C, and particularly preferably 10 to 30°C.

[0034] Although each step has been explained above using Figure 1, the fructan production method of the present invention can adopt different embodiments. [Figure 2] This is a typical example of the production of rakkyo fructan powder using rakkyo fresh produce or salting residue as raw materials. The purified narakkyo raw material is squeezed using a juicer to obtain a squeezed extract, which is then subjected to pH adjustment and solid-liquid separation.The fructan-containing solution obtained through these processes is then subjected to membrane separation to remove low molecular weight components, and the fructan powder can be obtained by concentrating and powdering.

[0035] [Figure 3] This is a typical example of the production of a concentrate containing rakkyo fructan, using rakkyo fresh produce or salted residue as raw materials. This is an example in which the final step (pulverization step) in FIG. 2 is omitted.

[0036] [Figure 4] This is one of the modified methods for producing rakkyo fructan powder using rakkyo fresh produce or salted residue as raw materials. This is an example in which the manufacturing method itself is simplified by omitting the pH adjustment step in Figure 2 and performing only solid-liquid separation, and fructan powder is obtained through the subsequent steps.

[0037] [Figure 5] This is a typical example of how pickling juice is used as a raw material to produce shallot fructan powder. The pickling liquid is diluted as necessary, pH adjusted, and solid-liquid separation is performed. The fructan-containing raw solution obtained through these processes is subjected to membrane separation to remove low molecular weight components, and fructan powder can be obtained by concentrating and powdering. Naturally, it is also possible to stop at the concentration step, or to use a portion of the obtained solution as a fructan concentrate.

[0038] [Figure 6] This is one of the variations for producing shallot fructan powder using pickling juice as the raw material. This is an example in which the manufacturing method itself is simplified by omitting the pH adjustment step in Figure 5 and performing only solid-liquid separation, and fructan powder is obtained through the subsequent steps.

[0039] [Figure 7] This is one of the variations for producing rakkyo fructan powder, in which the squeezed extract of rakkyo raw material is combined with the pickling liquid to form a fructan-containing solution raw material. The process is similar to that shown in Figure 2, but differs in that the squeezed extract and pickling liquid are used together (pickling liquid addition process). [Example]

[0040] The method for producing rakkyo fructan of the present invention will be described in detail.

[0041] <<Experiment, comparison of recovery rates using various raw materials>> 1. The following samples were used as raw materials for the fructan-containing solution. (1) Sample 1 Rakkyo fresh produce is washed, then water is added and homogenized. (2) Sample 2 Salted residue is homogenized with water. (3) Sample 3 This is a rakkyo product that has been homogenized while containing the fruit and seasoning liquid. (4) Sample 4 Pickling liquid (pH 3.72).

[0042] 2. Calcium hydroxide solution was added to each raw material to adjust the pH to about 10. The precipitate generated during the adjustment was removed by centrifugal sedimentation, and solid-liquid separation was carried out to obtain a liquid. The liquid obtained in 3.2 was filtered and then subjected to removal of small molecules using a dialysis membrane. A cellulose-based dialysis membrane with a pore size of 40 to 50 Å (molecular weight permeation: 12,000 to 16,000) was used as the dialysis membrane. 4. The purified liquid was concentrated and then freeze-dried to obtain white crystals. 5. For comparison, a product manufactured by a method according to the prior art (JP Patent Publication No. 10-158306) was used as a comparative example.

[0043] 6. The results are shown in Table 1 and Figure 8. In the table, recovery rate (Dry) indicates the fructan recovery rate per dry weight, and recovery rate (Wet) indicates the fructan recovery rate per wet weight. (1) In Experimental Example 1, the recovery rate (Dry) was 32%, while the recovery rate (Wet) was 10%. This was found to be the highest fructan recovery rate among the samples examined. (2) In Experimental Example 2, the recovery rate (Dry) was 16%, while the recovery rate (Wet) was 2.4%. Compared to Experimental Example 1, the recovery rate (Dry) was only about half. This strongly suggests that the fructan contained in the shallots is dissolved and liberated in the pickling solution during salting. This suggests the usefulness of recovering fructan from the pickling solution. (3) In Experimental Example 3, the recovery rate (Dry) was 6.6%, while the recovery rate (Wet) was 1.6%. The recovery rate (Dry) was approximately one-fifth of that in Experimental Example 1 and just over one-half of that in Experimental Example 2. In other words, it was estimated that fructans were dissolved and released in the seasoning solution and washing during the manufacturing process of shallot products. (4) In Experimental Example 4, the fructan content varied depending on the condition of the pickling liquid and the time of collection, but the recovery rate (wet) in this case was 0.5%. The applicant's factory alone generates a large amount of pickling liquid, 100 to 250 tons per year, and the disposal costs are high. Therefore, even if the fructan content in the pickling liquid is low, it is expected that at least 500 to 1,250 kg of fructan can be produced, and production will significantly reduce the disposal costs of the pickling liquid, making the production of fructan from pickling liquid extremely useful.

[0044] (5) As a result of gel filtration HPLC, in Experiment 1, the molecular weight ranged from 2,000 to 390,000, and the weight-average molecular weight was approximately 44,000. The estimated purity was 90%. (6) In Experimental Example 2, the molecular weight ranged from 500 to 350,000, with a weight-average molecular weight of approximately 37,000. The estimated purity was 83%. (7) In Experimental Example 3, the molecular weight ranged from 500 to 350,000, and the weight-average molecular weight was approximately 16,000. The estimated purity was 91%. (8) In Experimental Example 4, the molecular weight ranged from 500 to 75,000, and the weight-average molecular weight was approximately 9,000. The estimated purity was 80%. (9) These results indicate that fructans with different average molecular weights and molecular weight distributions can be obtained from each sample. In other words, by selecting the raw material, fructans with different molecular weight distributions can be obtained. Since different molecular weights are expected to affect absorption and effects in humans, the significance and usefulness of selecting raw materials to produce shallot fructans are demonstrated.

[0045] (10) On the other hand, in Experimental Example 5, a comparative example, the recovery rates were high (59% dry) and 18% wet, but the estimated purity was only 75%. It is believed that the low estimated purity was due to the presence of fructose, low-molecular-weight fructose polymers, and free amino acids in the final crystalline powder. It is also believed that the recovery rate (Dry) was overestimated due to the presence of low-molecular-weight fructose polymers. (11) In Experimental Example 6, the recovery rate (Dry) was 15% and the recovery rate (Wet) was 5.0%, resulting in a low estimated purity of 20%. It is believed that the large amount of sodium chloride contained in the recovered solid weight fraction contributed to the low estimated purity. Furthermore, after leaving the fructan powder for a certain period of time, the crystalline powder turned brown (not shown). (12) Furthermore, in the comparative examples, the fructan solution before drying had a savory smell of shallots in all experimental examples. This contrasts with the odorless fructan-containing solution after the membrane separation process in the examples.

[0046] 7. The salt content of the salted residue before fructan extraction was 15%, but after purification it was reduced significantly to about 2.3%. This indicates that the salted residue after extraction can be easily disposed of, and that it can be used as fertilizer for agricultural crops after processing such as fermentation. 8. In addition, with regard to rakkyo products, those that have failed quality inspections or have expired can be effectively utilized, and low molecular weight fructans can be obtained, which is expected to be useful. For example, by combining rakkyo products with pickling liquid that also produces low molecular weight fructans, waste can be effectively utilized.

[0047] [Table 1]

Claims

1. The pickling liquid generated when salting rakkyo is used as the raw material for rakkyo fructan, a pH adjustment step of adjusting the pH of the raw material solution to 9.0 to 11.5 and performing deproteinization; a solid-liquid separation step of performing solid-liquid separation on the raw material solution after the pH adjustment step; a membrane separation step of removing salt from the raw solution after the solid-liquid separation step by membrane separation; a concentration step of concentrating the raw material solution after the membrane separation; This method for producing rakkyo fructan is characterized by obtaining a rakkyo fructan solution from which salt has been removed.

2. A crushing process for crushing either or both of shallots, or shallot residue, which is the unnecessary part of salted shallots other than the fruit part as a product; A squeezing step of squeezing and extracting the pulverized material after the pulverization; The method for producing rakkyo fructan according to claim 1, wherein the solution obtained by the above step is further used as a raw material for rakkyo fructan.

3. Further, a drying and powdering step of obtaining a dry powder from the raw material solution after the concentration step by any one of freeze drying, spray drying, and vacuum drying; 3. The method for producing rakkyo fructan according to claim 1 or 2, wherein rakkyo fructan is obtained as a dry powder.

4. A method for producing radish fructan as described in claim 1, wherein membrane separation is performed using a separation membrane for molecular components of 10.0 kDa or less.

5. A method for producing radish fructan according to claim 1 or 2, wherein the steps other than the drying step are carried out at 10 to 50°C.

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