Method for preparing blue-purple sweet potato pigment

Abstract

To stably and efficiently provide a sweet potato-derived anthocyanin pigment composition showing a blue purple color tone from a weakly acidic region to a neutral region.SOLUTION: A method for preparing a sweet potato-derived anthocyanin pigment composition showing a bluish purple color tone or blue purple color tone from a weakly acidic region to a neutral region, includes: extracting a water-soluble composition indicating such a compositional feature that percentage contents of only three kinds of cyanidin type anthocyanin of a YGM-0c anthocyanin, a YGM-1a type anthocyanin and a YGM-2 type anthocyanin show 70-lower percent or more of the total anthocyanin, and the percentage content of the total of the cyanidin type anthocyanin shows 80 percent or more of the total anthocyanin, under an acid condition, by using a tuberous root of a sweet potato plant belonging to "Tyurakanasa" as a raw material.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a technique for stably and efficiently providing an anthocyanin pigment composition derived from sweet potato that exhibits a bluish-purple color in a weakly acidic to neutral range. [Background technology]

[0002] Anthocyanins are natural pigment compounds that exist in natural raw materials as pigment compositions, which are collections of similar compounds, and the compound composition varies greatly depending on the type and variety of the plant material. In addition to the combination of anthocyanidin, which is an aglycone, and sugar molecules, an enormous number of similar compound combinations exist for anthocyanins, depending on the presence and type of organic acids and various modifying groups, and each has different molecular properties related to color tone, stability, etc. Sweet potato pigment (sweet potato-derived anthocyanin pigment composition) is a pigment composition primarily composed of anthocyanins produced from sweet potato root tubers. It exhibits relatively favorable odor characteristics inherent to the raw materials and is a pigment material that does not require excessive deodorization during the refining process. Furthermore, because sweet potato pigment is a natural pigment derived from plant materials, it is in line with recent consumer trends toward natural products and is used as an excellent pigment in many fields, including food and beverages. Furthermore, in the production of color formulations and food and beverages, anthocyanin pigments with high antioxidant activity are required from the perspective of durability against light, heat, etc. The anthocyanins contained in sweet potato pigment have a structure known as the YGM type, which has three sugar molecules within the anthocyanin molecule and has polyphenol functional groups in the side chain, demonstrating excellent stability against light, heat, etc.

[0003] There are many types of anthocyanins contained in the existing purple sweet potato pigments currently in common use, and the majority of these anthocyanins are classified as YGM-type anthocyanins. Of these, YGM-1 to -3 types are cyanidin-type anthocyanins that exhibit a bluish-purple hue in the weakly acidic to neutral range, while YGM-4 to -6 types are peonidin-type anthocyanins that exhibit a purple to reddish-purple hue in the weakly acidic to neutral range. The only known sweet potato cultivars with high anthocyanin content in the flesh of tuberous roots currently used as pigment raw materials are those with a high content of peonidin-type anthocyanins (so-called purple sweet potatoes). Therefore, when extraction is performed using ordinary purple sweet potatoes as a raw material, only pigment compositions with a purple to reddish-purple color tone are obtained in the weakly acidic to neutral range.

[0004] Here, with regard to other existing sweet potatoes, among the sweet potato cultivars other than pigment raw materials, there are existing cultivars such as "Bise", "Okiyumemurasaki", and "Tanegashimamurasaki" that contain a lot of cyanidin-type anthocyanins. However, the anthocyanin content of the tuberous roots of "Bise" and "Okiyumemurasaki" is not high enough to be used as a pigment source (Non-Patent Document 1), and the yield of the tubers themselves tends to be low, making them unsuitable for use as a pigment source. Furthermore, while "Tanegashima Murasaki" tends to contain a large amount of cyanidin-type anthocyanins, there is a large variation in the pigment composition between individuals, and the anthocyanin content is also low, making it unsuitable as a pigment source (Non-Patent Document 2). In addition to the above, these anthocyanin compositions have a large number of types of anthocyanins (Non-Patent Documents 1 and 2), which tends to result in large variations between individuals and between cultivation periods, making it difficult to obtain blue-purple sweet potato pigments with a stable composition. [Prior art documents] [Non-patent literature]

[0005] [Non-Patent Document 1] Report of the Kyushu Branch of the Crop Science Society of Japan 84: p24-30, 2018, Comparison of anthocyanin content in purple sweet potato tuberous roots with different cultivation types in the Okinawa region [Non-patent document 2] Journal of the Japanese Society of Food Science and Technology (Nippon Shokuhin Kagaku Kogaku Kaishi) Vol. 46, No.3, p148-154 (1999), Composition and stability of sweet potato anthocyanin pigments Summary of the Invention [Problem to be solved by the invention]

[0006] The present invention aims to solve the above-mentioned problems and to stably and efficiently provide an anthocyanin pigment composition derived from sweet potato that exhibits a bluish-purple color tone in the weakly acidic to neutral range. [Means for solving the problem]

[0007] The present inventors conducted extensive research to solve the above-mentioned problems, and extracted a water-soluble pigment composition under acidic conditions from the flesh of the tuberous root of the sweet potato variety "Churakanasa," one of the many sweet potato varieties or lines developed by the applicant, NARO, and performed composition analysis.Surprisingly, the sweet potato pigment obtained contained just under 70% or more of the three types of cyanidin-type anthocyanins, namely YGM-0c-type anthocyanins, YGM-1a-type anthocyanins, and YGM-2-type anthocyanins, and furthermore, showed a high total content of cyanidin-type anthocyanins of over 80%, and was found to exhibit compositional characteristics that resulted in a blue-purple or bluish-purple color in the weakly acidic to neutral range. Furthermore, the sweet potato pigment exhibited compositional characteristics of containing a large amount of the above three types of anthocyanins, and contained less than 10% of other anthocyanins (mostly 0 to several % (w / w)).

[0008] Here, there are existing sweet potato cultivars that contain a large amount of cyanidin-type anthocyanins other than existing pigment raw materials. However, as mentioned above, it is difficult to obtain sweet potato pigments that exhibit a stable anthocyanin composition with a blue-purple hue from the tuberous roots of these existing sweet potato cultivars (for details, see the Background Art section and Experimental Example 2(7) described below). In contrast, the sweet potato pigment extracted from the flesh of the tuberous root of "Churakanasa" contained just under 70% of three types of cyanidin-type anthocyanins: YGM-0c-type anthocyanins, YGM-1a-type anthocyanins, and YGM-2-type anthocyanins, and exhibited compositional characteristics that resulted in a stable blue-purple color. Furthermore, the sweet potato pigments of "Churakanasa" exhibited a compositional characteristic of containing particularly high amounts of two types of cyanidin-type anthocyanins, YGM-0c and YGM-1a, (these two types alone account for nearly 50% or more), resulting in a more stable blue-purple color. Here, YGM-0c and YGM-1a anthocyanins are types of cyanidin-type anthocyanins that are not present at all or almost not present in existing sweet potato cultivars.

[0009] In addition to being a cultivar that exhibits the cultivation characteristic of early enlargement of the tuberous root, "Churakanasa" has a high anthocyanin content in the flesh of the tuberous root, making it suitable as a pigment source. Here, "Churakanasa" is a sweet potato strain originally developed for the prevention of weevil damage, but the flesh of its tuberous roots only exhibits a deep purple color, and the detailed anthocyanin composition and its color-developing properties have been unknown until now. In sweet potato plants, the anthocyanin composition varies depending on the part of the plant, even within the same cultivar, and the anthocyanin composition of the tuberous roots differs significantly between the skin and flesh. However, the inventors first discovered during the investigation of the experimental examples described below that the water-soluble pigment components extracted from the flesh of "Churakanasa" tuberous roots under acidic conditions (pH 3.5 or lower) exhibit anthocyanin compositional characteristics that can be stably used as a blue-purple sweet potato pigment, a color significantly different from the usual purple or reddish-purple sweet potato pigments. Furthermore, even when the flesh of the tuberous root of "Churakanasa" is used as the raw material, if extraction is carried out under alkaline conditions of pH 5 or higher, the extracted pigment composition will have a brown color even if it is subsequently adjusted to a weakly acidic to neutral range, and the blue-purple sweet potato pigment desired by the present invention cannot be obtained.

[0010] Based on the above findings, the inventors discovered that by using the fleshy part of the tuberous root of "Churakanasa" as a raw material and extracting water-soluble components under acidic conditions, it is possible to stably prepare an anthocyanin pigment composition derived from sweet potato that exhibits a bluish-purple color in the weakly acidic to neutral range, and thus completed the present invention. The present invention specifically relates to the inventions described below.

[0011] [Section 1] The method is characterized in that the tuberous root of a sweet potato plant belonging to "Churakanasa" (FERM-P22433) is used as a raw material, and extraction is carried out at a pH of 3.5 or less to extract a water-soluble composition exhibiting the following compositional characteristics: A method for preparing an anthocyanin pigment composition derived from sweet potato, which exhibits a bluish purple or blue-purple color in a weakly acidic to neutral range: (Compositional characteristics): The content of only three types of cyanidin-type anthocyanins, namely YGM-0c type anthocyanin, YGM-1a type anthocyanin, and YGM-2 type anthocyanin, accounts for more than 67% (w / w) of all anthocyanins, and the total content of cyanidin-type anthocyanins accounts for more than 80% (w / w) of all anthocyanins. [Section 2] Item 2. A method for preparing an anthocyanin pigment composition according to Item 1, wherein the compositional characteristics are such that the content of only two types of cyanidin-type anthocyanins, YGM-0c-type anthocyanin and YGM-1a-type anthocyanin, is 45% (w / w) or more of the total anthocyanins. [Section 3] Item 3. A method for preparing an anthocyanin pigment composition according to Item 1 or 2, wherein, with regard to the compositional characteristics, the content of each of the anthocyanins other than YGM-0c anthocyanins, YGM-1a anthocyanins, and YGM-2 anthocyanins is less than 10% (w / w) of the total anthocyanins. [Section 4] With respect to the compositional characteristics: The content of only three types of cyanidin-type anthocyanins, namely YGM-0c type anthocyanin, YGM-1a type anthocyanin, and YGM-2 type anthocyanin, is 70% (w / w) or more of the total anthocyanins. The content of only two types of cyanidin-type anthocyanins, YGM-0c type anthocyanin and YGM-1a type anthocyanin, accounts for 50% (w / w) or more of the total anthocyanins. The total content of cyanidin-type anthocyanins is 81% (w / w) or more of all anthocyanins, and The content of each anthocyanin other than YGM-0c type anthocyanin, YGM-1a type anthocyanin, and YGM-2 type anthocyanin is less than 10% (w / w) of the total anthocyanins. Item 4. A method for preparing the anthocyanin pigment composition according to any one of Items 1 to 3. [Section 5] In the method for preparing an anthocyanin pigment composition, Instead of sweet potato plants belonging to the "Churakanasa" (FERM-P22433) A sweet potato plant belonging to a progeny or mutant population of a sweet potato plant belonging to "Churakanasa" (FERM-P22433), in which the anthocyanin composition contained in the flesh of its tuberous root shows the same or higher content of three types of cyanidin-type anthocyanins, namely, YGM-0c-type anthocyanin, YGM-1a-type anthocyanin, and YGM-2-type anthocyanin, as "Churakanasa" (FERM-P22433), and the two types of cyanidin-type anthocyanin, YGM-0c-type anthocyanin and YGM-1a-type anthocyanin, are contained in the flesh of its tuberous root. A sweet potato plant having the characteristics of having a content of cyanidin-type anthocyanins equal to or higher than that of "Churakanasa" (FERM-P22433), a total content of cyanidin-type anthocyanins equal to or higher than that of "Churakanasa" (FERM-P22433), and an individual content of each anthocyanin other than YGM-0c-type anthocyanins, YGM-1a-type anthocyanins, and YGM-2-type anthocyanins equal to or lower than that of "Churakanasa" (FERM-P22433). Item 5. The method for preparing an anthocyanin pigment composition according to any one of Items 1 to 4, wherein the water-soluble composition is extracted using tuberous roots of the anthocyanin pigment composition as a raw material. [Section 6] Item 6. The method for preparing an anthocyanin pigment composition according to any one of Items 1 to 5, wherein the flesh of the tuberous root of the sweet potato plant is used as a raw material for extracting the water-soluble composition. [Section 7] Regarding the anthocyanin content of the flesh of the tuberous root, the raw material color value (E 10% cm Item 7. The method for preparing an anthocyanin pigment composition according to Item 6, wherein the value of (a) is 5 or more. [Section 8] Item 8. The method for preparing an anthocyanin pigment composition according to any one of Items 1 to 7, wherein the extraction of the water-soluble composition is carried out at a pH of 3 or less. [Section 9] A method for producing an anthocyanin pigment composition derived from sweet potato, comprising using the preparation method according to any one of items 1 to 8. [Section 10] Item 10. A method for producing a pigment preparation or food or drink, comprising a step of blending or containing a sweet potato-derived anthocyanin pigment composition obtained by the production method according to Item 9. [Effects of the Invention]

[0012] According to the present invention, it is possible to stably and efficiently provide an anthocyanin pigment composition derived from sweet potato that exhibits a bluish-purple color tone in the weakly acidic to neutral range. [Brief explanation of the drawings]

[0013] [Figure 1] 1 shows chromatograms obtained by HPLC analysis of aglycone composition (anthocyanin composition) in Experimental Example 2 (3). Top: Results of sweet potato pigments from "Ayamurasaki." Bottom: Results of sweet potato pigments from "Churakanasa." [Figure 2] 1 shows the results of MS analysis and MS / MS analysis of peak a of the sweet potato pigment "Churakanasa" in Experimental Example 2(4). Upper: MS analysis results. Lower: MS / MS analysis results. [Figure 3] 1 shows the results of MS analysis and MS / MS analysis of peak b of the sweet potato pigment "Churakanasa" in Experimental Example 2(5). Upper: MS analysis results. Lower: MS / MS analysis results. DETAILED DESCRIPTION OF THE INVENTION

[0014] Hereinafter, embodiments of the present invention will be described in detail, but the technical scope of the present invention is not limited to embodiments that include all of the configurations described below. Furthermore, the technical scope of the present invention does not exclude embodiments that include configurations other than those described below, as long as they do not substantially impede the effects achieved by the technical features of the present invention.

[0015] 1. Explanation of terms As used herein, "sweet potato plant (sweet potato)" refers to a plant belonging to Ipomoea batatas (L.) Lam. In this specification, the term "line" refers to a subclassification of "species" and is used to refer to a population that has external and / or physiological characteristics (phenotype) that are distinguishable as a group from other varieties or lineages. Among lineages, a population that has sufficiently similar uniformity in the characteristics of the same generation and is stable enough to maintain the characteristics over generations is called a "variety," and varieties are also included as part of lineages.

[0016] In this specification, "tuberous root" refers to the tuber, which is the underground storage organ of the sweet potato plant. In this specification, "top-grade sweet potato" is a term that refers to a potato weighing 50g or more. "Top-grade sweet potato weight" refers to the yield (kg / a) of top-grade sweet potatoes per planted area (1a). "Weight of one top-grade sweet potato" refers to the weight (g) of one top-grade sweet potato.

[0017] In this specification, the term "L*a*b* value" refers to coordinate values ​​indicating color tone (hue and lightness) in the CIE Lab color system, and refers to coordinate values ​​in a color system that forms a color solid consisting of an orthogonal coordinate system consisting of the a* and b* axes indicating hue and an L* axis perpendicular to the a* axis indicating lightness. Here, the "L* value" is a value that numerically expresses lightness, with an L* value of 100 indicating white and an L* value of 0 indicating black. The "a* value" is a value that numerically expresses the red and green hues, with a higher a* value indicating a stronger red and a lower a* value indicating a stronger green. The "b* value" is a value that numerically expresses the yellow and blue hues, with a higher b* value indicating a stronger yellow and a lower b* value indicating a stronger blue.

[0018] In this specification, the term "color value" refers to a value (E 10% cm) This value is based on the absorbance of the pigment contained in 1 g of the pigment composition (sample) and can be used as a measure of the pigment content contained in 1 g of the pigment composition (sample) (a value that can be compared between samples). In this specification, the maximum absorption wavelength (λmax) used in calculating color values ​​can be 530 nm, which is the average maximum absorption wavelength of anthocyanins. The 1 / 10 in the formula is a coefficient for converting to 10% (w / v). [Formula (1)] E 10% cm = (1 / 10) × volume of dilution solvent (g) × absorbance at maximum absorption wavelength (λmax) / sample weight (g) Formula (1)

[0019] The color value in this specification can also be used as a "raw material color value," which is a measure of the pigment content contained in 1 g of raw material tuberous root (sample) (a relative value that can be compared between samples). In the case of raw material color value, an operation to obtain an extract from the raw material tuberous root (sample) is required, so E 10% cm can be expressed using the following formula (2). [Formula (2)] E 10% cm = (1 / 10) × volume of diluted solution (g) × [volume of extraction solvent (g) + sample weight (g)] × absorbance at maximum absorption wavelength (λmax) / sample weight (g) Formula (2)

[0020] In this specification, "anthocyanidin" refers to the aglycone of an anthocyanin compound, which is a compound that forms the backbone structure of an anthocyanin compound by binding with a sugar molecule or the like. The general structural formula of anthocyanidin can be shown as the following structural formula (I). R in structural formula (I) 11 ~R 17indicates either a hydrogen atom (-H), a hydroxyl group (-OH), or a methoxy group (-OCH3). Anthocyanidins consist of three ring structures: A ring, B ring, and C ring. They are primarily classified into six groups: pelargonidin, cyanidin, delphinidin, peonidin, petunidin, and malvidin, depending on the type and number of hydrogen atoms (-H), hydroxyl groups (-OH), and methoxy groups (-OCH3) attached to the B ring (the benzene ring on the right side of structural formula (I)). Other examples include aurantidin, luteolinidin, europinidin, and rosinidin. These compounds have a variety of different colors when they become the constituent aglycones of anthocyanin compounds. In the present specification, "cyanidin" refers to a compound represented by the following structural formula (I): 11 , R 12 , R 14 , R 15 , and R 17 indicates a hydroxyl group (-OH), and R 13 and R 16 represents a hydrogen atom (-H). In this specification, cyanidin may be abbreviated as "Cy." In the present specification, "peonidin" refers to a compound represented by the following structural formula (I): 11 indicates a methoxy group (-OCH3), and R 12 , R 14 , R 15 , and R 17 indicates a hydroxyl group (-OH), and R 13 and R 16 represents a hydrogen atom (-H). In this specification, peonidin may be abbreviated as "Pn."

[0021] [ka]

[0022] In this specification, "anthocyanin" refers to a natural pigment compound derived from plant materials that exhibits various colors, and refers to a glycoside in which a sugar molecule is bound to an anthocyanidin skeleton via a glycosidic bond (o-glycosidic bond). 14 and / or R 15In the anthocyanin molecular structure, where sugar molecules are bound to the anthocyanidin skeleton, this is the site where sugar molecules are bound via a glycosidic bond (o-glycosidic bond). An organic acid may further bind to the sugar molecule to form an acylated anthocyanin. There are many molecular species of anthocyanins with different modification patterns depending on the type of aglycone, the type and binding position of the sugar molecule, and the presence, type, and binding position of the organic acid. Anthocyanins vary in color tone and various properties depending on these structural differences. As used herein, the term "cyanidin-type anthocyanin" refers to a glycoside in which a sugar molecule is bound to a cyanidin skeleton. That is, cyanidin-type anthocyanin refers to an anthocyanin compound that contains a cyanidin skeleton as the anthocyanidin skeleton, and exhibits a bluish-purple color development characteristic in the weakly acidic to neutral range. As used herein, the term "peonidin-type anthocyanin" refers to a glycoside in which a sugar molecule is bound to a peonidin skeleton. That is, peonidin-type anthocyanin refers to an anthocyanin compound that contains a peonidin skeleton as the anthocyanidin skeleton, and exhibits color development characteristics of purple to reddish purple in the weakly acidic to neutral range.

[0023] In this specification, the term "sweet potato pigment" is used synonymously with "sweet potato-derived anthocyanin pigment composition" and refers to a water-soluble pigment composition containing anthocyanin as the main pigment obtained by extraction using the tuberous root (the flesh of the tuberous root) of a sweet potato plant as a raw material. The term "anthocyanin pigment composition" refers to a pigment composition containing anthocyanin as the main pigment component or consisting of anthocyanin as the pigment component. Sweet potato pigments exhibit relatively good odor characteristics inherent to the raw materials and are a pigment material that does not require excessive deodorization during the refining process. Furthermore, the anthocyanins contained in sweet potato pigments have a structure known as the YGM type, which has three sugar molecules per molecule, and many of them have acylation-modifying functional groups in their side chains, which gives them excellent stability against light and heat. The anthocyanins contained in existing purple sweet potato pigments are classified into eight types: YGM-1a, YGM-1b, YGM-2, YGM-3, YGM-4b, YGM-5a, YGM-5b, and YGM-6, although there are also a few types that belong to the YGM-0 type.

[0024] In this specification, "YGM-0c type anthocyanin" refers to the compound represented by the structural formula (II) below, which is cyanidin-3-parahydroxybenzoylsophoroside-5-glucoside. It has a p-hydroxybenzoic acid modifying group in its molecular structure. YGM-0c type anthocyanin is rarely found in existing sweet potatoes. In this specification, "YGM-1a type anthocyanin" refers to the compound represented by the following structural formula (III), cyanidin-3-caffeoyl-p-hydroxybenzoylsophoroside-5-glucoside. Its molecular structure contains a caffeic acid modifying group and a p-hydroxybenzoic acid modifying group. YGM-1a type anthocyanin is also present in existing sweet potatoes, but its content is small. As used herein, "YGM-2 anthocyanin" refers to a compound represented by the following structural formula (IV), cyanidin-3-caffeoylisophoroside-5-glucoside. Its molecular structure contains a caffeic acid modifying group. YGM-2 anthocyanin is also present in existing sweet potato cultivars. YGM-0c anthocyanin, YGM-1a anthocyanin, and YGM-2 anthocyanin are all YGM anthocyanins that have three sugar molecules, are acylated anthocyanins that have organic acid modifying groups in their molecular structure, and are cyanidin anthocyanins that have a cyanidin skeleton as the anthocyanidin skeleton.

[0025] [ka]

[0026] [ka]

[0027] [ka]

[0028] 2. Preparation of anthocyanin pigment composition derived from sweet potato The present invention relates to a method for preparing an anthocyanin pigment composition, which is characterized by extracting a water-soluble composition using, as a raw material, the tuberous root of a sweet potato plant belonging to a specific sweet potato lineage. The anthocyanin pigment composition of the present invention exhibits compositional characteristics derived from the water-soluble pigment components contained in the flesh of the tuberous roots of a specific sweet potato line, which is the extraction raw material, and the sweet potato pigment of the present invention exhibits color development characteristics that reflect these compositional characteristics. The method for preparing the pigment composition according to the present invention can be carried out by the steps described below, and the steps other than those relating to the raw plant material are not limited to the steps described below, as long as they do not substantially impede the effects of the technical features of the present invention.

[0029] [Raw materials] The preparation method according to the present invention is characterized in that the sweet potato plant used as the raw material is a sweet potato plant belonging to "Churakanasa" or a sweet potato plant belonging to its progeny population or mutant population. "Churakanasa" is a sweet potato line developed by the present applicant, the National Agriculture and Food Research Organization. The pigment composition contained in its tuberous roots exhibits desirable characteristics as a blue-purple sweet potato pigment, not seen in other sweet potato varieties, in terms of the anthocyanin composition of the flesh of the tuberous root. "Churakanasa" also exhibits excellent characteristics in terms of raw material color value and potato cultivation characteristics (top potato weight, weight per top potato, etc.). "Churakanasa" has been applied for deposit with the International Patent Organism Depositary Center by the present applicant, and has been assigned the accession number FERM P-22433.

[0030] In the preparation method of the present invention, it is preferable to use a sweet potato plant belonging to the "Churakanasa" variety. Specifically, it is preferable to use a sweet potato plant that has the characteristics of exhibiting the same anthocyanin composition as the pigment composition shown below in terms of the pulp of its tuberous root. Specifically, the anthocyanin composition contained in the flesh of the tuberous root is comprised of only three types of cyanidin-type anthocyanins, namely YGM-0c anthocyanins, YGM-1a anthocyanins, and YGM-2 anthocyanins, with a content of just under 70% or more of the total anthocyanins. Furthermore, the anthocyanin composition contained in the flesh of the tuberous root is comprised of only two types of cyanidin-type anthocyanins, namely YGM-0c anthocyanins and YGM-1a anthocyanins, with a content of just under 50% or more of the total anthocyanins. Furthermore, the anthocyanin composition contained in the flesh of the tuberous root is comprised of a total content of cyanidin-type anthocyanins of more than 80% of the total anthocyanins. Furthermore, the anthocyanin composition contained in the flesh of the tuberous root is comprised of a total content of peonidin-type anthocyanins of less than 20% of the total anthocyanins. Furthermore, with regard to the anthocyanin composition contained in the flesh of the tuberous root, the content of each anthocyanin other than YGM-0c type anthocyanin, YGM-1a type anthocyanin, and YGM-2 type anthocyanin is less than 10% of the total anthocyanins (mostly 0 to several % (w / w)). Here, the anthocyanin composition of the flesh of the tuberous root of "Churakanasa" can be cited by referring to the numerical ranges shown in the composition of the pigment composition below.

[0031] The cultivation characteristics of the tuberous roots of "Churakanasa" include, for example, the raw material color value (E 10% cm ) is 5 or more, preferably 5.6 or more. In addition, preferred examples include those having a top tuber weight of 180 kg / are or more, preferably 200 kg / are or more, more preferably 223 kg / are or more. In addition, preferred examples include those having a weight per top tuber of 100 g or more, preferably 117 g or more. It is preferable to use values ​​indicating the cultivation characteristics of these tuberous roots when cultivated by a person skilled in the art of sweet potato cultivation (such as an agricultural testing institute).

[0032] Furthermore, in the preparation method of the present invention, sweet potato plants belonging to a progeny or mutant population of "Churakanasa" can also be used as starting plants. As the sweet potato plants belonging to the progeny or mutant population, those that exhibit an anthocyanin composition of the pigment composition contained in the flesh of their tuberous roots that is equivalent to or more suitable than that of "Churakanasa" can be used. Specifically, it is preferable to use a sweet potato plant that has the characteristic that, with regard to the anthocyanin composition contained in the flesh of its tuberous root, the content of three types of cyanidin-type anthocyanins, namely YGM-0c-type anthocyanins, YGM-1a-type anthocyanins, and YGM-2-type anthocyanins, is the same as or higher than that of "Churakanasa." It is also preferable to use a sweet potato plant that has the characteristic that, with regard to the anthocyanin composition contained in the flesh of its tuberous root, the content of two types of cyanidin-type anthocyanins, namely YGM-0c-type anthocyanins and YGM-1a-type anthocyanins, is the same as or higher than that of "Churakanasa." It is also preferable to use a sweet potato plant that has the characteristic that, with regard to the anthocyanin composition contained in the flesh of its tuberous root, the total content of cyanidin-type anthocyanins is the same as or higher than that of "Churakanasa." It is also preferable to use a sweet potato plant that has the characteristic that, with regard to the anthocyanin composition contained in the flesh of its tuberous root, the total content of peonidin-type anthocyanins is the same as or lower than that of "Churakanasa."It is also preferable to use a sweet potato plant that has the characteristic that, with regard to the anthocyanin composition contained in the flesh of its tuberous root, the content of each anthocyanin other than YGM-0c-type anthocyanins, YGM-1a-type anthocyanins, and YGM-2-type anthocyanins is the same as or lower than that of "Churakanasa." Here, the anthocyanin composition of the flesh of the tuberous root of the progeny population or mutant population can be cited by reference to the description of "Churakanasa" or the numerical ranges shown in the composition of the pigment composition below. Furthermore, it is preferable to use a progeny population or mutant population that exhibits cultivation characteristics related to tuberous roots that are equivalent (the same) to or more suitable than those of "Churakanasa."

[0033] Herein, "Churakanasa progeny population (or progeny line)" refers to a crossbreeding population (child population) obtained using "Churakanasa" as one or both of the breeding parents, and its progeny population. Further crossbreeding populations between these and other breed lines, and their progeny populations, are also included here. Furthermore, the progeny population also includes these further progeny populations. Furthermore, in this specification, the term "mutant population of Churakanasa (mutant population, mutant line)" refers to a population in which the mutant traits of mutants (mutant individuals) created by mutation, gene introduction, genome editing, etc. of "Churakanasa" have been fixed. This also includes progeny populations that possess the mutant traits.

[0034] The preparation method according to the present invention is characterized in that the pulp of the tuberous root is used as the raw material for extraction of the pigment composition. As the raw material for extraction, the pulp (enlarged inner tissue of the potato or the inner tissue of the tuberous root excluding the skin), which is a starch-storing organ rich in anthocyanins, is preferably used. Here, even if the extraction raw material contains both the pulp and the skin of the tuberous root (or other plant tissues or organs), it can be used as the extraction raw material according to the present invention as long as the pigment composition obtained after extraction exhibits the following properties. However, in order to prepare a pigment composition exhibiting a predetermined anthocyanin composition, it is preferable to use only the pulp portion of the tuberous root. Here, there are varieties of sweet potato plants in which the anthocyanin composition between the skin and flesh of the tuberous root is significantly different. Furthermore, there are many varieties in which the color tone of the skin differs from that of the cut surface of the potato, revealing differences in anthocyanin composition between the two, even when visually observed. In light of these points, it is preferable to select and use the flesh of the tuberous root as the extraction raw material for the present invention in order to obtain a pigment composition with the desired anthocyanin composition of the extracted pigment. Furthermore, the flesh of the tuberous root makes up the majority of the tissue that makes up the potato, so it can be used advantageously in terms of securing a sufficient amount of pigment raw material.

[0035] [extraction] In the preparation method of the present invention, it is possible to prepare a pigment composition by extracting water-soluble components from the raw material. The extraction can be performed by any known or unknown method as long as it is capable of extracting water-soluble pigment components from the tuberous root pulp of sweet potato. In addition, in the preparation method of the present invention, the residue after extraction and the squeezed residue can be reused as raw materials.

[0036] For extraction from raw materials, it is preferable to use raw materials that have been cut, chopped, fragmented, crushed, crushed, pulverized, or the like in order to increase extraction efficiency. The extraction solvent is preferably water or an aqueous solution. The aqueous solution may contain various salts, organic acids, pH adjusters, pH buffers, lower alcohols, etc. Alternatively, an aqueous alcohol may be used. The amount of solvent used relative to the raw materials is not particularly limited, but for example, 0.1 to 1000 parts by mass of solvent per 1 part by mass of raw materials, preferably 0.5 to 100 parts by mass of solvent per 1 part by mass of raw materials, can be used.

[0037] An acidic aqueous solution can be used as the extraction solvent for extracting the anthocyanin pigment composition from the raw material. The extraction is preferably performed at a pH of 0.1 to 3.5, more preferably 0.1 to 3.2, and particularly preferably 0.1 to 3. From the viewpoint of the color tone and extraction efficiency of the anthocyanin pigment composition, the extraction is preferably performed at a pH of 3.5 or less, preferably 3.2 or less, and particularly preferably 3 or less. From the viewpoint of practical operability, the lower limit of the pH can be 0.1 or more, 0.5 or more, 1 or more, 1.2 or more, 2 or more, or 2.2 or more. Conventional pH adjusters and pH buffers can be used to adjust the pH. For example, hydrochloric acid and sulfuric acid can be used. Furthermore, when considering use in foods and beverages, examples of pH adjusters that can be used include citric acid, phosphoric acid, acetic acid, succinic acid, trisodium citrate, sodium bicarbonate, potassium carbonate, gluconic acid, tartaric acid, lactic acid, and fumaric acid. It is also possible to use salt compounds of these compounds. Because anthocyanins have high solubility in water, there are no particular limitations on the extraction temperature. For example, at normal pressure, a temperature of 1 to 80°C, preferably 1 to 60°C, and more preferably 1 to 40°C can be used. The upper limit of the temperature is preferably 80°C or less, 60°C or less, or 40°C or less. To prevent anthocyanin discoloration, the temperature can be 40°C or less, preferably 30°C or less, more preferably 20°C or less, and particularly preferably 10°C or less. Because anthocyanins have high solubility in water, extraction is possible at temperatures of 1°C or higher; however, from the viewpoint of practical ease of use, a temperature of 3°C or higher is preferred. It is also possible to use an aqueous solution containing alcohol as the extraction solvent. The alcohol concentration can be 0 to 99.5% (v / v). From the viewpoint of anthocyanin extraction efficiency, the upper limit of the alcohol concentration can be 99% (v / v) or less, preferably 90% (v / v) or less, and more preferably 80% (v / v) or less. Examples of the type of alcohol include monohydric lower alkyl alcohols such as methanol, ethanol, propanol, isopropanol, and butanol, with methanol or ethanol being preferred. Considering application to foods and beverages, it is particularly preferred to use ethanol. The extraction time can be determined appropriately taking into consideration conditions such as temperature, etc. For example, it can be about 1 minute to several days, but is not particularly limited to this.

[0038] [Other processes] In the method for preparing a pigment composition according to the present invention, an anthocyanin pigment composition of desired quality and / or form can be obtained depending on the desired application by performing solid-liquid separation, purification, concentration, dilution, pH adjustment, drying, sterilization, etc. These steps can be performed in combination as desired, or a desired treatment can be performed multiple times. Furthermore, in the method for preparing a pigment composition according to the present invention, it is preferable to obtain an anthocyanin pigment composition from which raw material residues and / or impurities have been removed by performing solid-liquid separation, purification, etc. However, it is also possible to employ an embodiment in which the raw material residues and / or impurities remain as they are in the extract without performing any particular treatment such as solid-liquid separation or purification, etc. Alternatively, it is also possible to employ an embodiment in which the extract and raw material residues and / or impurities remain mixed together.

[0039] In the method of the present invention, a pH adjustment step can be carried out after the extraction step to adjust the pH value so that the anthocyanin pigment composition has a desired color tone. In particular, it is preferable to adjust the pH value so that the anthocyanin pigment composition of the present invention has a pH in the weakly acidic to neutral range described below, so that the anthocyanin pigment composition of the present invention can fully exhibit the color-developing properties of a blue-purple sweet potato pigment.

[0040] The dye composition according to the present invention can be in various forms such as liquid, paste, gel, semi-solid, solid, and powder. Furthermore, the dye composition according to the present invention can be embodied in such a manner that other functional components, etc., are blended therein, as long as they do not substantially impair the color-developing properties, compound stability, etc. For example, antioxidants, pH adjusters, thickening polysaccharides, other food ingredients, etc. can also be blended therein.

[0041] [Anthocyanin pigment composition] In the preparation method of the present invention, the water-soluble anthocyanin components are dissolved in the solvent by the extraction, and a pigment composition containing anthocyanin as a main pigment is obtained. The pigment composition is an anthocyanin pigment composition derived from sweet potato (sweet potato pigment).

[0042] The anthocyanin pigment composition obtained by the above process exhibits compositional characteristics including a high total content of three types of cyanidin-type anthocyanins: YGM-0c-type anthocyanin, YGM-1a-type anthocyanin, and YGM-2-type anthocyanin. The anthocyanin pigment composition exhibits a compositional characteristic in which the combined content of the three anthocyanins (YGM-0c, YGM-1a, and YGM-2 anthocyanins) alone is 67% (w / w) or more, preferably 67.7% (w / w) or more, more preferably 70% (w / w) or more, particularly preferably 76% (w / w) or more, and even more preferably 76.2% (w / w) or more of the total anthocyanins. This compositional characteristic results in a stable blue-purple hue. There is no upper limit to this value, but examples include 80% (w / w) or less, 79% (w / w) or less, or 78.5% (w / w) or less. Because the majority of the anthocyanin pigment composition is made up of only three molecular species, it exhibits the characteristic of exhibiting a stable blue-purple hue. As for the compositional characteristics of the anthocyanin pigment composition, as long as the total amount of the three types of cyanidin-type anthocyanins satisfies the above range, there are no particular restrictions on the individual contents of the YGM-0c type anthocyanin, YGM-1a type anthocyanin, and YGM-2 type anthocyanin. These three types are "cyanidin-type anthocyanins" that are structurally similar and exhibit blue-purple color-developing characteristics. Even if the content of any one of these three is low, as long as the total of these three types satisfies the above range, the blue-purple color characteristics of the anthocyanin pigment composition are guaranteed. In other words, as long as the total of these three types satisfies the above range, there are no particular restrictions on the individual contents of these three types.

[0043] As described above, the content of YGM-0c type anthocyanins in the anthocyanin pigment composition is not particularly limited as long as the total of the above three types is satisfied, but suitable examples include 11.4% (w / w) or more of all anthocyanins, preferably 12% (w / w) or more, more preferably 16% (w / w) or more, even more preferably 20% (w / w) or more, particularly preferably 30% (w / w) or more, and even more preferably 30.4% (w / w) or more. Furthermore, the content of YGM-1a type anthocyanin in the anthocyanin pigment composition is preferably 18.7% (w / w) or more of all anthocyanins, preferably 19% (w / w) or more, more preferably 20% (w / w) or more, even more preferably 30% (w / w) or more, particularly preferably 34% (w / w) or more, and even more preferably 34.9% (w / w) or more. Furthermore, the anthocyanin pigment composition preferably contains 2.7% (w / w) or more of the YGM-2 anthocyanin, preferably 3% (w / w) or more, more preferably 5% (w / w) or more, even more preferably 8% (w / w) or more, even more preferably 10% (w / w) or more, and even more preferably 10.9% (w / w) or more of the total anthocyanins. Even if the content of YGM-2 anthocyanin in the anthocyanin pigment composition is low, the blue-purple color characteristics of the anthocyanin pigment composition are ensured for the reasons described above, as long as the total amount of these three anthocyanins falls within the above range.

[0044] Furthermore, the YGM-0c type anthocyanin and YGM-1a type anthocyanin contained in this anthocyanin pigment composition are molecular species of anthocyanin that are not contained at all or almost not at all in existing sweet potato pigments, and it is recognized that this sweet potato pigment exhibits novel compositional characteristics in that it contains particularly large amounts of these two types of cyanidin type anthocyanins. In this regard, the compositional characteristics of the anthocyanin pigment composition are preferably such that, while satisfying the total content of the three anthocyanins, the combined content of the two anthocyanins, YGM-0c anthocyanin and YGM-1a anthocyanin, accounts for 45% (w / w) or more of the total anthocyanins, preferably 45.3% (w / w) or more, more preferably 46% (w / w) or more, even more preferably 50% (w / w) or more, particularly preferably 65% ​​(w / w) or more, and even more preferably 65.3% (w / w) or more. There is no particular upper limit to this value, but examples include 75% (w / w) or less, 73% (w / w) or less, or 72.3% (w / w) or less. An anthocyanin pigment composition exhibiting these compositional characteristics exhibits a more stable blue-purple hue because the majority of the composition is made up of only two molecular species.

[0045] Furthermore, as a compositional feature of the anthocyanin pigment composition, from the viewpoint of exhibiting the color-developing properties of the blue-purple sweet potato pigment, the total content of cyanidin-type anthocyanins is 80% or more (80% (w / w) or more) of all anthocyanins, while satisfying the total of the above three components. Specifically, preferred examples include those in which the total content of cyanidin-type anthocyanins is 81% (w / w) or more of all anthocyanins, preferably 81.6% (w / w) or more, more preferably 85% (w / w) or more, and particularly preferably 85.4% (w / w) or more. There is no particular upper limit to this value, but examples include 95% (w / w) or less, 93% (w / w) or less, or 92.7% (w / w) or less. Furthermore, as a compositional feature of the anthocyanin pigment composition, from the viewpoint of color development properties with little reddish tinge, the total content of peonidin-type anthocyanins is 20% or less (20% (w / w) or less) of the total anthocyanins, while satisfying the total of the above three components. Specifically, preferred examples include those in which the total content of peonidin-type anthocyanins is 19% (w / w) or less of the total anthocyanins, preferably 18.4% (w / w) or less, more preferably 15% (w / w) or less, and even more preferably 14.4% (w / w) or less. There is no particular lower limit to this value, but examples include 5% (w / w) or more, 7% (w / w) or more, or 7.3% (w / w) or more.

[0046] The anthocyanin pigment composition obtained by the above process exhibits compositional characteristics including a high content of the total of the above three types of anthocyanins belonging to the cyanidin-type anthocyanins. In this regard, the anthocyanin pigment composition obtained by the above process is characterized in that anthocyanins other than the three types of anthocyanins, YGM-0c anthocyanin, YGM-1a anthocyanin, and YGM-2 anthocyanin, are minor or only trace pigment components, and the content of each of these anthocyanins is below a certain level. More specifically, the content of each of the anthocyanins other than YGM-0c anthocyanin, YGM-1a anthocyanin, and YGM-2 anthocyanin is less than 10% (w / w), preferably less than 9% (w / w), and more preferably less than 8% (w / w) of the total anthocyanins. Furthermore, the anthocyanin pigment composition is characterized by the fact that there are only a few minor or trace anthocyanins other than these three, with only 5 to 6 minor pigments (5 to 7 if trace amounts are included) clearly detected by HPLC analysis. In this regard, the anthocyanin composition of the sweet potato pigments of "Churakanasa" is composed of three major pigments and a total of 8 to 9 major and minor pigments (8 to 10 if trace amounts are included), each containing a few percent (w / w). Compared to the pigments of existing sweet potato varieties that contain a large amount of cyanidin-type anthocyanins, this composition has a smaller number of major and overall anthocyanin types. The compositional characteristics shown above are significantly different from existing sweet potato cultivars that contain many major pigment components, and exhibit compositional characteristics that make it easy to obtain blue-purple sweet potato pigments with stable composition and little variation between individuals and cultivation periods.

[0047] The anthocyanin pigment composition obtained by the above process exhibits color development characteristics of a bluish purple or blue-purple color in the weakly acidic to neutral range due to the compositional characteristics of the anthocyanins. The pH range in which the color development characteristics are exhibited can be pH 4 to 8, preferably pH 4 to 7.6, more specifically pH 5 to 7, and particularly preferably pH 6 to 7. The pH range of 5 to 7 is considered to be a suitable pH range for use as a blue-purple sweet potato pigment because it is significantly different in color from existing purple or reddish-purple sweet potato pigments (see Examples below) and is in high demand in the food and beverage industry.

[0048] The anthocyanin pigment composition obtained by the above process may contain anthocyanins other than the three types of anthocyanins and other pigment compounds, and these other anthocyanins and other pigment compounds are also permitted to be contained as long as they do not substantially impair the color-developing properties, compound stability, etc.

[0049] 3. Various inventions The present invention includes various inventions characterized by incorporating or containing the anthocyanin pigment composition prepared as described above. For example, the present invention includes an invention relating to a method for producing an anthocyanin pigment composition derived from sweet potato (sweet potato pigment), and an invention relating to a method for producing a pigment preparation, food or drink, etc. Here, the manufacturing steps in each of these manufacturing methods can be performed in the same manner as in the various technical fields, except that the anthocyanin pigment composition is used. In addition, in order to fully utilize the color-developing properties of the blue-purple sweet potato pigment, it is preferable to adjust or make the pH value of these various products to be in the weakly acidic to neutral range described above. Depending on the intended use, it is also possible to blend the blue-purple sweet potato pigment with other pigment compounds or pigment agents to produce a pigment preparation, food, drink, etc., adjusted to achieve the desired final color tone. This embodiment is also recognized as an embodiment utilizing the blue-purple sweet potato pigment as a pigment material. [Example]

[0050] The present invention will be described below with reference to examples, but the scope of the present invention is not limited to these examples.

[0051] [Experimental Example 1] "Study of raw sweet potatoes" We investigated the sweet potatoes suitable for preparing blue-purple sweet potato pigments.

[0052] (1) "Characteristics of tuberous root growth (yield of potato)" For the sweet potato variety "Churakanasa" developed by the National Agriculture and Food Research Organization, cultivation tests were conducted in spring planting in a field in Miyakonojo City, Miyazaki Prefecture, and in autumn planting in a field in Itoman City, Okinawa Prefecture, and potato yield (tuberous root growth) was investigated. As a control, a similar test was also conducted on the purple sweet potato variety "Churakoibeni." As a result, the characteristics of tuberous root growth when "Churakanasa" was cultivated were comparable to or better than "Chura Koibeni" (control), a purple sweet potato that exhibits excellent potato yield characteristics, in terms of the yield of top-grade potatoes per planting area (top-grade potato weight), the number of top-grade potatoes per plant, and the weight of each top-grade potato.These results were similar when two cultivation tests were conducted in different growing environments and the two were compared.

[0053] [Table 1]

[0054] (2) "Anthocyanin content in the flesh of tuberous roots (raw material color value)" The flesh of the tuberous root obtained above (5 g) was cut into sticks of approximately 5 mm in size, and 0.5% sulfuric acid (100 ml) was added to prepare a solution of pH 1.2. The solution was left to stand overnight in a dark refrigerator (3-7°C) to extract the water-soluble components, and then filtered to obtain an extract containing water-soluble pigment components. 1 ml of the obtained extract was filled up to 10 ml with McIlvaine buffer (pH 3), and the absorbance at 530 nm was measured using a spectrophotometer to determine the raw material color value (E 10% cm The results are shown in the table below. As a result, the raw material color value (E 10% cm ) showed values ​​indicating that its anthocyanin content was at least as high as that of the control, a purple sweet potato variety called "Chura Koibeni," which is rich in anthocyanins. The results were similar when comparing tuberous roots harvested from two cultivation trials in different growing environments.

[0055] [Table 2]

[0056] (3) “Small summary” As a result of the above study, it was shown that "Churakanasa" is a sweet potato variety that exhibits growth characteristics that result in high potato yields equal to or greater than those of cultivated purple sweet potato varieties, and that has a sufficiently high anthocyanin content in the flesh of the tuberous root. Here, "Churakanasa" is a strain originally developed for the purpose of preventing damage caused by weevils, and the flesh of its tuberous root (raw sweet potato) is only dark purple, with its detailed anthocyanin composition and coloring characteristics unknown. However, the results of the tests described below have revealed that the water-soluble pigment composition extracted from the flesh of the tuberous root of "Churakanasa" is a water-soluble pigment composition with a bluish-purple hue that is significantly different in color from the pigments of ordinary purple sweet potatoes.

[0057] [Experimental Example 2] Analysis of the color and composition of sweet potato pigments The sweet potato pigment (water-soluble pigment composition) extracted from the tuberous root pulp of "Churakanasa" was analyzed for its color tone and composition of the pigment compounds contained.

[0058] (1) "Color tone of sweet potato pigments with pH changes" The flesh (5 g) of the tuberous root of "Churakanasa" was cut into approximately 5 mm sticks, added to 100 ml of McIlvaine buffer (pH 2.2), and left overnight in a dark refrigerator (3-7°C) to extract the water-soluble components. The extract was then filtered to obtain an extract containing anthocyanins. 20 ml of the extract was adsorbed onto 5 ml of resin (MCI gel CHP20P, Mitsubishi Chemical Corporation) to remove impurities, and then eluted with 2 ml of 80% ethanol. The concentration of this eluate was adjusted based on absorbance at 530 nm, and it was mixed with 5% McIlvaine buffer of each pH shown in Table 3 to confirm the color change.

[0059] As a result, it was revealed that the color of the extract from "Churakanasa" changes from bluish purple to blue-purple as the pH increases from the weakly acidic to neutral range (pH 4-7), with the a* and b* values ​​decreasing, and at pH levels above 7, the a* value drops sharply, the color becomes greener, and the extract assumes a deep blue tone. In particular, it was shown that the extract assumes a vivid blue-purple tone at pH levels of 5-7, and even at pH levels of 6-7. On the other hand, a similar extraction was performed on "Ayamurasaki" (control), a purple sweet potato that is conventionally used as a raw material for pigment extraction, and color analysis was performed.The results showed that the color of the extract was reddish purple or purple in the weakly acidic to neutral range (pH 4 to 7), and light blue to greenish blue in the pH range above pH 7, and that the color became lighter as the pH increased.

[0060] [Table 3]

[0061] (2) "HPLC analysis of anthocyanin composition" The flesh (5 g) of the tuberous root of "Churakanasa" was cut into 5 mm sticks, and 0.5% sulfuric acid (100 ml) was added to prepare a solution of pH 1.2. The solution was left overnight in a refrigerator (3-7°C) to extract the water-soluble components, and then filtered to obtain an extract containing anthocyanins. An extract of "Ayamurasaki," a control purple sweet potato, was also prepared in the same manner. Using the obtained extracts as sample solutions, HPLC analysis was performed by co-chromatography on the extracts of "Churakanasa" and the purple sweet potato "Ayamurasaki" using the following equipment and conditions. In addition, a similar analysis was performed using YGM-6 as a standard substance, and the anthocyanin amounts corresponding to the respective waveform peaks and total amounts in the samples were calculated as the YGM-6 equivalent amounts.

[0062] (Apparatus and conditions used for HPLC analysis) Equipment: LC10, 20 series (Shimadzu) Column: Cadenza CD-C18 (4.6 x 250 mm, 3 μm) (GL Sciences) LC conditions Mobile phase: 0.6% formic acid in water / 50% acetonitrile containing 0.6% formic acid Flow rate: 0.6mL / min Temperature: 35℃ Measurement wavelength: 520nm Gradient conditions (Time) (0.6% formic acid in water) (0.6% formic acid in 50% acetonitrile) 0 minutes: 20% 80% 50 minutes: 50% 50%

[0063] As a result, it was confirmed that the extract of "Ayamurasaki" (control), which is used as a raw material for regular sweet potato pigments, contained peaks representing as many as 16 distinct compounds. Eight of these peaks were recognized as peaks representing eight types of YGM-type anthocyanins based on existing information. In contrast, 8-9 types of peaks were clearly detected in the extract of "Churakanasa" (8-10 types if trace amounts are included), and peaks representing three types of compounds (peak a, peak b, and peak c) were detected as peaks showing a content of 10% (w / w) or more. These peaks were detected as major peaks at 520 nm, the maximum absorption wavelength of anthocyanins, and therefore all were recognized as peaks representing anthocyanins.

[0064] Here, the anthocyanin content of the "Churakanasa" extract was calculated, and the anthocyanins represented by peak a accounted for 30.4% (w / w) of the total anthocyanins, the anthocyanins represented by peak b accounted for 34.9% (w / w) of the total anthocyanins, and the anthocyanins represented by peak c accounted for 10.9% (w / w) of the total anthocyanins. That is, the sweet potato pigments contained in the flesh of the tuberous root of "Churakanasa" subjected to this analysis were found to be only three types of anthocyanins: anthocyanins represented by peak a, anthocyanins represented by peak b, and anthocyanins represented by peak c, which accounted for 76.2% (w / w) of the total anthocyanins. In addition, the anthocyanins represented by peak a and anthocyanins represented by peak b were found to be only two types of anthocyanins, which accounted for 65.3% (w / w) of the total anthocyanins. In addition to these three peaks, five to six clear peaks (five to seven including minute ones) were confirmed, but with regard to the anthocyanins represented by these, even the largest peak among these represented only 7.9% (w / w) of the total anthocyanins, and the majority were trace peaks representing less than a few percent (w / w) of the total anthocyanins.

[0065] (3) "HPLC analysis of aglycone composition (anthocyanidin content)" The extract from the flesh of the tuberous root of "Churakanasa" prepared in the same manner as above (2) was subjected to acid decomposition treatment by adding 30% hydrochloric acid and heating at 90°C for 2 hours, and a reaction was carried out to separate the aglycone anthocyanidin. The resulting reaction solution was used as a sample solution and subjected to HPLC analysis in the same manner as described in (2) above. A similar test was also performed on the purple sweet potato variety "Ayamurasaki" as a control. The results are shown in Figure 1.

[0066] As a result, it was confirmed that the extract of "Ayamurasaki" (control), which is used as a raw material for conventional sweet potato pigments, contained peaks representing peonidin and cyanidin in relation to the anthocyanin aglycone, and that the peak representing peonidin in particular was detected as the large, major peak. In contrast, in the extract of "Churakanasa," the peak representing cyanidin was detected as the major peak regarding the anthocyanin aglycone, and the peak representing peonidin was only detected as a minor peak.

[0067] These results indicate that the sweet potato pigments contained in the flesh of the tuberous roots of "Churakanasa" are characterized by an anthocyanin composition characterized by cyanidin-type anthocyanins as the main anthocyanin type. Furthermore, it was revealed that the sweet potato pigments contained in the flesh of the tuberous roots of "Churakanasa" are sweet potato pigments whose total content of cyanidin-type anthocyanins is 85.4% (w / w) of the total anthocyanins. Furthermore, it was revealed that the sweet potato pigments contained in the flesh of the tuberous roots of "Churakanasa" are sweet potato pigments whose total content of peonidin-type anthocyanins is 14.4% (w / w) of the total anthocyanins.

[0068] [Table 4]

[0069] (4) "Analysis of Peak a" Peak a detected in the HPLC analysis described in (2) above was a peak not present in the waveform of "Ayamurasaki" in the cochromatographic analysis. Therefore, to identify the compound represented by peak a, MS analysis and MS / MS analysis were performed, and the structure was estimated from the obtained accurate mass value. Here, the mass analysis was performed using the following equipment. The HPLC analysis conditions were the same as those described in (2) above. The results are shown in Figure 2.

[0070] (Equipment used for HPLC / MS analysis) Instrument: [MS] micrOTOFQ III (Bruker Daltonics) [LC] L-2000U series (Hitachi High-Technologies Corporation) Column: InertSustain Swift C18 (4.6 x 150 mm, 5 μm) (GL Sciences)

[0071] The results showed that the compound shown as peak a in the HPLC analysis was detected as a peak with an m / z value of 893.23, and the decomposition peak representing the cyanidin skeleton was detected as a peak with an m / z value of 449.11. Based on the accurate mass values, the peak with an m / z value of 731.18 was identified as a compound representing an anthocyanin with one glucose atom missing from the 5' position, and the peak with an m / z value of 287.06 was identified as sophoroside. Based on the above findings and existing knowledge of anthocyanin molecular structures, it was revealed that the compound indicated by peak a is a compound indicating "YGM-0c type anthocyanin" (the above structural formula (II)).

[0072] (5) "Analysis of Peak b" Peak b detected in the HPLC analysis described in (2) above was a peak whose identity could not be confirmed in the waveform of "Ayamurasaki" in the cochromatographic analysis. Therefore, to identify the compound represented by peak b, MS analysis and MS / MS analysis were performed, and the structure was estimated from the obtained accurate mass value. Here, the mass analysis was performed using the apparatus described in (4) above. The HPLC analysis conditions were the same as those described in (2) above. The results are shown in Figure 3.

[0073] The results showed that the compound shown as peak b in the HPLC analysis was detected as a peak with an m / z value of 1055.26, and the decomposition peak representing the cyanidin skeleton was detected as a peak with an m / z value of 449.11. Based on the accurate mass values, the peak with an m / z value of 893.21 was identified as a compound representing an anthocyanin with one glucose atom missing from the 5' position, and the peak with an m / z value of 287.06 was identified as sophoroside. Based on the above findings and existing knowledge of anthocyanin molecular structures, it was revealed that the compound represented by peak b is a compound representing "YGM-1a type anthocyanin" (the above structural formula (III)).

[0074] (6) "Analysis of Peak c" Peak c detected in the HPLC analysis (2) above was confirmed to have the same retention time as the peak representing YGM-2 type anthocyanin in the waveform of "Ayamurasaki" in the cochromatographic analysis, and to be a peak representing anthocyanin. This revealed that the compound shown by peak c in the HPLC analysis was a compound representing "YGM-2 type anthocyanin" (the above structural formula (IV)).

[0075] (7) “Small summary” The analysis results revealed that the sweet potato pigments contained in the flesh of the tuberous roots of "Churakanasa" were a water-soluble pigment composition (sweet potato-derived anthocyanin pigment composition) characterized by a high content of three types of cyanidin-type anthocyanins: YGM-0c, YGM-1a, and YGM-2. Furthermore, these three types of cyanidin-type anthocyanins alone accounted for 76% (w / w) of the total anthocyanins, and the total content of cyanidin-type anthocyanins accounted for 85% (w / w) of the total anthocyanins. Meanwhile, the total content of peonidin-type anthocyanins was only 15% (w / w). Furthermore, the content of each of the anthocyanins other than these three types was less than 8% (w / w) of the total anthocyanins (a few percent (w / w) or less, or not detected). Furthermore, the YGM-0c and YGM-1a anthocyanins contained in the sweet potato pigments extracted from the flesh of the tuberous roots of "Churakanasa" are molecular species of anthocyanins that are not present at all or are almost not present in existing sweet potato cultivars. The sweet potato pigments in question are found to be particularly rich in these two types of cyanidin anthocyanins (the total of the two types accounts for 65% (w / w) of all anthocyanins), and are sweet potato pigments that exhibit novel compositional characteristics.

[0076] While sweet potato pigments containing many anthocyanin molecular species, which are the main pigment components, tend to have unstable pigment component compositions, the sweet potato pigments extracted from the flesh of the tuberous roots of "Churakanasa" contained more than 70% of all anthocyanins consisting of only three types of anthocyanins belonging to the cyanidin type. These three types are "cyanidin type anthocyanins" that have similar structures and exhibit blue-purple coloring characteristics. Even if the content of any one of these three is low, as long as the total content of these three types satisfies the above criteria, the blue-purple color characteristics of the anthocyanin pigment composition are guaranteed. Furthermore, with regard to anthocyanins other than these three, only five to six types (five to seven types including trace amounts) were clearly detectable by HPLC analysis. In contrast, the pigments of the sweet potato "Churakanasa" consist of three main anthocyanin pigments (8 to 10 types in total, including the main pigments and minor pigments, which are present in a content of about a few percent (w / w)), and the composition showed a small number of types of major anthocyanins and anthocyanins overall. In this regard, it was recognized that the sweet potato pigments of the new variety exhibit a compositional characteristic of having a smaller number of anthocyanin types than existing varieties of sweet potato that contain a large amount of cyanidin-type anthocyanins. Here, the sweet potato pigments of the existing variety "Bise" have 4 to 5 types of major anthocyanin pigments (11 or more types of major and minor pigments in total), the sweet potato pigments of "Okiyumemurasaki" have 4 to 5 types of major anthocyanin pigments (14 or more types of major and minor pigments in total), and the sweet potato pigments of "Tanegashimamurasaki" have 4 types of major anthocyanin pigments (14 types of major and minor pigments in total), exhibiting a compositional characteristic of having a large number of types of major anthocyanins and anthocyanins overall (Non-Patent Documents 1 and 2).

[0077] From the above results, the sweet potato pigment from the flesh of the tuberous root of "Churakanasa" was found to be an anthocyanin pigment composition with compositional characteristics indicating a stable blue-purple sweet potato pigment, since only three molecular species (particularly two of them) account for the majority of the composition. Furthermore, the results of the composition analysis showed compositional characteristics that ensure its function as a water-soluble pigment that exhibits a bluish purple or blue-purple hue in weakly acidic to moderate acidic ranges.

[0078] [Experimental Example 3] "Analysis of anthocyanin composition of sweet potato pigments extracted from multiple individuals" A large number of individuals belonging to the variety "Churakanasa" were cultivated, and the stability of the anthocyanin composition of sweet potato pigments (water-soluble pigment compositions) extracted from the flesh of the tuberous roots was evaluated.

[0079] (1) "Analysis of anthocyanin composition" The pulp of the tuberous root from each of 26 "Churakanasa" individuals (samples 1-20: grown in Miyakonojo City, Miyazaki Prefecture; samples 21-26: grown in Itoman City, Okinawa Prefecture) shown in the table below was used as the analytical sample. The pulp of the tuberous root (5 g) was shredded into 5 mm sticks, and 0.5% sulfuric acid (100 ml) was added to prepare a solution with a pH of 1.2. The solution was left overnight in a dark refrigerator (3-7°C) to extract the water-soluble components, and filtered to obtain an extract containing anthocyanins. The composition of the extract was analyzed as described in Experimental Example 2(2). The types and contents of anthocyanins detected by this analysis are shown in the table below. The pH of the extract was adjusted to a neutral range, and the color was visually observed, as shown in the table below.

[0080] The results showed that pigment compositions extracted from the pulp of tuberous roots of "Churakanasa" cultivated in both Miyazaki and Okinawa prefectures exhibited a compositional characteristic of being rich in three types of "cyanidin-type anthocyanins": YGM-0c, YGM-1a, and YGM-2 anthocyanins. Even the individual with the lowest total content of these three anthocyanins accounted for more than 67% (w / w) of the total anthocyanins, and most individuals accounted for more than 70% (w / w). While some individuals had low levels of YGM-2 anthocyanins, the total amount of the three anthocyanins accounted for more than 70% of the total anthocyanins, and the anthocyanin pigment compositions exhibited a bluish-purple color. Furthermore, the results of this analysis confirmed that "Churakanasa" sweet potato contains particularly high amounts of two types of cyanidin-type anthocyanins, YGM-0c-type anthocyanin and YGM-1a-type anthocyanin, which are characteristic of sweet potato pigments, and that even the individual with the lowest amount contained more than 45% (w / w) of the total anthocyanins (approximately just under 50%), and most individuals contained more than 50% (w / w). Furthermore, in all of the pigment compositions from these 26 individuals, it was confirmed that the majority of trace peaks of anthocyanins other than these three types were less than a few percent (w / w) or close to 0% (w / w) of the total anthocyanins, and even in the most abundant cases, were less than 10% (w / w) of the total anthocyanins.

[0081] From the above results, it was confirmed that the sweet potato pigment extracted from the flesh of the tuberous root of "Churakanasa" is an anthocyanin pigment composition that stably exhibits blue-purple coloring characteristics even when the cultivation conditions or individual plants are different.

[0082] [Table 5]

[0083] [Table 6]

[0084] (2) "Analysis of aglycone composition" The tuberous root pulp of each of the 16 "Churakanasa" individuals shown in the table below (samples 12-17, 27-30: cultivated in Miyakonojo City, Miyazaki Prefecture; samples 21-26: cultivated in Itoman City, Okinawa Prefecture) was used as the analysis sample, and extraction procedures were performed in the same manner as in (1) above. Next, a pigment composition was extracted and subjected to acid hydrolysis in the same manner as in Experimental Example 2 (3), and composition analysis of the liberated aglycone, anthocyanidin, was performed. Here, samples 12-17 (Miyakonojo City, Miyazaki Prefecture) and samples 21-26 (Itoman City, Okinawa Prefecture) represent the same individuals analyzed in the test in (1) above. Samples 27-30 (Miyakonojo City, Miyazaki Prefecture) represent additional individuals analyzed in this test. From the types and contents of anthocyanidins detected by this analysis, the ratio of each anthocyanidin type to the total anthocyanins contained in the pigment composition was calculated, and the results are shown in the table below. The pH of the extract obtained by the extraction procedure (the solution before the acid decomposition treatment) was adjusted to a neutral range, and the color tone was visually observed, as shown in the table below.

[0085] As a result, pigment compositions extracted from the pulp of the tuberous roots of "Churakanasa" cultivated in both Miyazaki Prefecture and Okinawa Prefecture exhibited compositional characteristics characterized by a very high total content of cyanidin-type anthocyanins. Specifically, the total content of cyanidin-type anthocyanins was confirmed to be 81% (w / w) or more (more than 80%) of the total anthocyanins in even the lowest individual, and 85% (w / w) or more in most individuals. Furthermore, the total content of peonidin-type anthocyanins was confirmed to be 19% (w / w) or less (less than 20%) of the total anthocyanins in even the highest individual, and 15% (w / w) or less in most individuals. Furthermore, the color tone of all these anthocyanin pigment compositions was confirmed to be a blue-purple hue. From the above results, it was confirmed that the sweet potato pigment extracted from the flesh of the tuberous root of "Churakanasa" is an anthocyanin pigment composition that stably exhibits blue-purple coloring characteristics even when the cultivation conditions or individual plants are different.

[0086] [Table 7]

[0087] [Table 8]

[0088] [Experimental Example 4] "Examination of pH conditions during extraction" The color development characteristics of sweet potato pigments (water-soluble pigment compositions) extracted from the flesh of the tuberous roots of "Churakanasa" were investigated when the pH conditions during extraction were changed.

[0089] (1) “pH conditions” The flesh (5 g) of the tuberous root of "Churakanasa" was cut into thin strips of approximately 5 mm, and 100 ml of McIlvaine buffer was added to prepare a solution of pH 2.2, pH 3, pH 4, pH 5, pH 6, pH 7, or pH 8. The extract was prepared and column purified in the same manner as in Experimental Example 2(1), except that the solution was left to stand overnight in a refrigerator (3 to 7°C) to extract the water-soluble components. The pH was then adjusted to a neutral range with McIlvaine buffer, and the color was observed. As a result, it was shown that when the extraction conditions for the pigment composition from the flesh of the tuberous root were adjusted to a pH value of 3 or below, the obtained pigment composition exhibited a blue-purple hue in the neutral range, and the extraction efficiency (pigment amount in the extract: anthocyanin pigment amount) was also good. On the other hand, when extraction was performed at pH 4 and then adjusted to a neutral range, the color was blue, but also slightly greenish. In particular, when extraction was performed at pH 5 or higher, the color was brownish when adjusted to a neutral range. Furthermore, the extraction efficiency (amount of pigment in the extract: amount of anthocyanin pigment) was also low. These results indicate that, with regard to the extraction conditions for the pigment composition from the pulp of the tuberous root of "Churakanasa," in order to obtain a sweet potato pigment with a bluish hue, it is necessary to perform the extraction under pH conditions of below pH 4 (the preferred range estimated from these results is pH 3.5 or lower). Furthermore, it was shown that in order to obtain a sweet potato pigment with a particularly good blue-purple hue with high efficiency, it is preferable to perform the extraction under pH conditions of below pH 3.

[0090] [Table 9]

[0091] [Experimental Example 5] "Examination of extraction conditions" The color development characteristics of sweet potato pigments (water-soluble pigment compositions) extracted from the flesh of the tuberous roots of "Churakanasa" were investigated under various extraction conditions.

[0092] (1) “Temperature conditions” The flesh (5 g) of the tuberous root of "Churakanasa" was cut into thin strips of approximately 5 mm, and 100 ml of McIlvaine buffer solution (pH 2.2) was added. The extract was then left to stand overnight at a low temperature (3-7°C) or at a slightly higher room temperature (35-40°C) to extract the water-soluble components. The extract was then prepared and purified using a column in the same manner as in Experimental Example 2(1), and the pH was adjusted to a neutral range using McIlvaine buffer solution, and the color was observed. As a result, when extracting the water-soluble composition from the pulp of the tuberous root, whether the temperature was low or slightly higher than room temperature, the resulting pigment composition exhibited a similar blue-purple hue in the neutral range. These results suggest that water-soluble pigment components with similar compositional characteristics are extracted regardless of the temperature conditions, from low to slightly higher than room temperature (3 to 40°C). Furthermore, it was confirmed that the extraction efficiency was approximately the same (approximately the same amount of anthocyanin pigment was extracted) regardless of the temperature at which extraction was performed.

[0093] (2) "Ethanol condition" The flesh (5 g) of the tuberous root of "Churakanasa" was cut into thin strips of approximately 5 mm, and 100 ml of McIlvaine buffer solution (pH 2.2), a solution containing 20% ​​(v / v) ethanol in McIlvaine buffer solution (pH 2.2), a solution containing 40% (v / v) ethanol in McIlvaine buffer solution (pH 2.2), a solution containing 60% (v / v) ethanol in McIlvaine buffer solution (pH 2.2), a solution containing 80% (v / v) ethanol in McIlvaine buffer solution (pH 2.2), or an absolute ethanol solution (ethanol 99.5% (v / v)) was added. The extract was prepared and column purified in the same manner as in Experimental Example 2(1), except that the extract was left to stand overnight in a refrigerator (3 to 7°C) to extract the water-soluble components. The pH was adjusted to a neutral range with McIlvaine buffer solution, and the color was observed. As a result, regarding the extraction conditions for the water-soluble composition from the pulp of the tuberous root, regardless of whether extraction was performed with a solution containing 80% (v / v) or less of ethanol, the resulting pigment composition exhibited a similar blue-purple hue in the neutral range. These results suggest that even when extraction was performed using an aqueous solution containing 80% (v / v) or less of ethanol, water-soluble pigment components with compositional characteristics similar to those extracted from an aqueous solution without ethanol were extracted. Furthermore, regarding the extraction efficiency, it was confirmed that regardless of whether extraction was performed with a solution containing 80% (v / v) or less of ethanol, the extraction efficiency was approximately the same (approximately the same amount of anthocyanin pigment was extracted). On the other hand, when extraction was performed with 99.5% (v / v) ethanol, the pigments contained in the resulting extract were significantly weaker, indicating that the anthocyanin extraction efficiency was significantly lower.

[0094] [Biological deposit] The applicant has deposited "Churakanasa" with a depository institution. "Churakanasa" was applied for deposit with the Patent Organism Depositary Center of the National Institute of Technology and Evaluation on October 13, 2021, and was assigned the following accession number.

[0095] (1) Name and address of the depository institution Name: National Institute of Technology and Evaluation, Patent Organism Deposit Center Address: Room 120, 2-5-8 Kazusa Kamatari, Kisarazu City, Chiba Prefecture, 292-0818 (2) Date of deposit Deposit date (acceptance date): October 13, 2021 Receipt Notification Date: December 6, 2021 (3) Accession number FERM P-22433: Ipomoea batatas (L.) Lam. (4) Characteristics of the deposited organism The characteristics of the deposited organism of FERM P-22433 are as described in the description of the present specification and in the Examples. Information on the taxonomic position and scientific properties of the deposited organism is as follows: · Taxonomic position: Ipomoea batatas (L.) Lam. Scientific information: The genome is autohexaploid. The above-ground parts are mainly composed of stems, petioles, and leaf blades. The petioles have a 2 / 5 alternate leaf arrangement and branches emerge from the main stem. Adventitious roots elongate from root primordia at the nodes and swell to form tuberous roots, which are starch storage organs. Flower buds differentiate under short-day conditions and flower at a certain temperature. [Industrial Applicability]

[0096] The technology of the present invention relates to a blue-purple sweet potato pigment that has not been widely distributed until now, and is expected to be used in various business fields, including food and beverages and processed foods, where natural pigments are preferred. [Explanation of symbols]

[0097] Cy: Peak indicating cyanidin Pn: Peak indicating peonidin [Accession number]

[0098] FERM P-22433

Claims

1. The method is characterized in that the tuberous roots of sweet potato plants belonging to "Churakanasa" (FERM-P22433) are used as raw materials, and extraction is carried out at a pH of 3.5 or less to extract a water-soluble composition exhibiting the following compositional characteristics: A method for preparing a sweet potato-derived anthocyanin pigment composition that exhibits a bluish purple or blue-purple color in a weakly acidic to neutral range: (Compositional characteristics): The content of only three types of cyanidin-type anthocyanins, namely YGM-0c-type anthocyanin, YGM-1a-type anthocyanin, and YGM-2-type anthocyanin, accounts for 67% (w / w) or more of all anthocyanins, and the total content of cyanidin-type anthocyanins accounts for 80% (w / w) or more of all anthocyanins.

2. The method for preparing an anthocyanin pigment composition according to claim 1, wherein the compositional characteristics are such that the content of only two types of cyanidin-type anthocyanins, YGM-0c-type anthocyanin and YGM-1a-type anthocyanin, is 45% (w / w) or more of the total anthocyanins.

3. 3. The method for preparing an anthocyanin pigment composition according to claim 1 or 2, wherein, with regard to the compositional characteristics, the content of each of the anthocyanins other than YGM-0c type anthocyanin, YGM-1a type anthocyanin, and YGM-2 type anthocyanin is less than 10% (w / w) of the total anthocyanins.

4. With respect to the compositional characteristics: The content of only three types of cyanidin-type anthocyanins, namely YGM-0c-type anthocyanin, YGM-1a-type anthocyanin, and YGM-2-type anthocyanin, is 70% (w / w) or more of the total anthocyanins, The content of only two types of cyanidin-type anthocyanins, YGM-0c-type anthocyanin and YGM-1a-type anthocyanin, is 50% (w / w) or more of the total anthocyanins, The total content of cyanidin-type anthocyanins is 81% (w / w) or more of all anthocyanins, and The content of each of the anthocyanins other than YGM-0c type anthocyanin, YGM-1a type anthocyanin, and YGM-2 type anthocyanin is less than 10% (w / w) of the total anthocyanins. A method for preparing the anthocyanin pigment composition according to any one of claims 1 to 3.

5. The method for preparing an anthocyanin pigment composition according to any one of claims 1 to 4, wherein the flesh of the tuberous root of the sweet potato plant is used as a raw material for extracting the water-soluble composition.

6. Regarding the anthocyanin content of the flesh of the tuberous root, the raw material color value (E １０％ ｃｍ 6. The method for preparing an anthocyanin pigment composition according to claim 5, wherein the value of (a) is 5 or more.

7. The method for preparing an anthocyanin pigment composition according to any one of claims 1 to 6, wherein the extraction of the water-soluble composition is carried out at a pH of 3 or less.

8. A method for producing an anthocyanin pigment composition derived from sweet potato, comprising using the preparation method according to any one of claims 1 to 7.

9. A method for producing a pigment preparation or a food or drink, comprising a step of blending or containing the sweet potato-derived anthocyanin pigment composition obtained by the production method according to claim 8.

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