Fermented dairy product containing purple sweet potato juice and fruit juice

Abstract

To provide a purple sweet potato squeezed juice-containing fermented milk product that has a good flavor in spite of containing purple sweet potato squeezed juice, does not increase sourness during storage and thus does not lose its flavor, and does not lose color during storage, and to provide a method for producing the same.SOLUTION: Provided are a fermented milk product that is characterized by containing purple sweet potato squeezed juice and one or more juices of fruit selected from the group consisting of grape, orange and blueberry, and a method for producing a fermented milk product that is characterized by including a step of mixing purple sweet potato squeezed juice with one or more juices of fruits selected from the group consisting of grape, orange and blueberry.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a fermented milk product containing purple taro juice and fruit juice and a method for producing the same.

Background Art

[0002] Purple taro contains a large amount of anthocyanins and has various effects such as improving liver function, so it is expected to be utilized in various forms of food and drink. For example, technologies related to lactic acid fermented foods obtained by fermenting lactic acid bacteria with a mixture of purple taro (Yamakawa Purple) juice containing a large amount of anthocyanin pigment and milk are known (Patent Document 1). In this Patent Document 1, since the anthocyanins contained in purple taro are decomposed by lactic acid bacteria during fermentation, the color tone at the end of fermentation varies depending on the type of lactic acid bacteria, and it is described that attention should be paid to the selection of lactic acid bacteria.

[0003] On the other hand, the present inventors prepared a fermented milk product containing purple taro juice in fermented milk instead of a fermented milk product in a state where purple taro juice exists during fermentation of milk, and found three problems: the flavor of the fermented milk product is not very good, the sourness becomes strong during storage and the flavor deteriorates, and the pigment fades during storage.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] Therefore, the problem to be solved by the present invention is to solve the problems in the fermented milk product containing purple taro juice as described above.

Means for Solving the Problems

[0006] The inventors diligently researched the above problems and, as a result, discovered that the flavor problem could be solved by combining purple sweet potato juice with a specific fruit juice and incorporating it into a fermented dairy product, thus completing the present invention. Furthermore, they discovered that the storage problem could be solved by controlling the pH of the above fermented dairy product, thus completing the present invention.

[0007] In other words, the present invention is a fermented dairy product characterized by containing purple sweet potato juice and one or more fruit juices selected from the group consisting of grapes, oranges, and blueberries.

[0008] Furthermore, the present invention is a method for producing a fermented dairy product, characterized by comprising the step of mixing fermented milk with purple sweet potato juice and one or more fruit juices selected from the group consisting of grapes, oranges, and blueberries.

[0009] Furthermore, the present invention is a method for improving the flavor of a fermented dairy product, characterized by adding one or more fruit juices selected from the group consisting of grapes, oranges, and blueberries to a fermented dairy product containing purple sweet potato juice.

[0010] Furthermore, the present invention is a method for suppressing discoloration of fermented dairy products, characterized by adjusting the pH of a fermented dairy product containing purple sweet potato juice and one or more fruit juices selected from the group consisting of grapes, oranges, and blueberries to 4.3 or less.

[0011] Furthermore, the present invention is a method for suppressing discoloration of fermented dairy products, characterized by adjusting the pH of the fermented dairy product obtained by mixing fermented milk with anthocyanin-containing juice and / or anthocyanin-containing fruit juice to 4.3 or less. [Effects of the Invention]

[0012] Despite containing purple sweet potato juice, the fermented dairy product of the present invention has a good flavor.

[0013] Furthermore, the fermented dairy products of the present invention are excellent because they do not become excessively sour during storage, thus preserving their flavor, and their pigments do not fade during storage. [Modes for carrying out the invention]

[0014] The fermented dairy product of the present invention contains purple sweet potato juice and one or more fruit juices selected from the group consisting of grapes, oranges, and blueberries.

[0015] The purple sweet potato juice used in the fermented dairy product of the present invention is obtained by extracting juice from the tubers of purple sweet potatoes containing anthocyanins using a known extraction method. The purple sweet potato is not particularly limited, but examples include Ayamurasaki, Murasakimasari, Yamakawa Murasaki, and Tanegashima Murasaki. Among these purple sweet potatoes, Ayamurasaki, which contains a large amount of anthocyanins, is preferred. Commercially available purple sweet potato juice can also be used. The concentration of fruit juices and vegetable juices is determined based on the straight juice obtained by extracting them, and can typically be determined based on the standard value (°Bx) of the sugar refractometer reading specific to each fruit and vegetable as shown in the JAS standard (Japanese Agricultural Standards for Fruit Beverages). For example, according to the JAS standard, straight juice of purple sweet potato has a Brix of 11. The content of purple pea juice in the fermented dairy product of the present invention is not particularly limited, but if it is more than 15% by mass, the acidity of the fermented dairy product during storage will increase significantly, so it is 5 to 15% by mass (hereinafter simply referred to as "%)" on a straight basis, preferably 5 to 11%.

[0016] The grape juice used in the fermented dairy product of the present invention is not particularly limited and may be obtained by pressing grapes of varieties such as red grapes like Tintorera, Red Globe, Flame Seedless, and Emperor, or white grapes like Pedro Ximénez, Cereza, Torrontés, Moscatel, and Malvasia using known pressing methods. The grape juice content in the fermented dairy product of the present invention is not particularly limited, but is 0.5 to 23%, preferably 1.5 to 15%, more preferably 3 to 15%, and most preferably 5 to 9% on a straight basis. The grape juice may be a combination of one or more grape varieties. Straight grape juice is Brix 11.

[0017] The orange juice used in the fermented dairy product of the present invention is not particularly limited and can be obtained by pressing oranges of varieties such as Pera, Natal, and Valencia using known juicing methods. The orange juice content in the fermented dairy product of the present invention is not particularly limited, but is 3 to 15%, preferably 5 to 9%, on a straight basis. The orange juice may be a combination of one or more orange varieties. Note that straight orange juice has a Brix of 11.

[0018] The blueberry juice used in the fermented dairy product of the present invention is not particularly limited and can be obtained by extracting juice from blueberry fruits of varieties such as Cultivate using known extraction methods. The blueberry juice content in the fermented dairy product of the present invention is not particularly limited, but is 3 to 15%, preferably 5 to 9%, on a straight juice basis. The blueberry juice may be a combination of one or more blueberry varieties. Straight blueberry juice has a Brix of 10.

[0019] The fermented dairy product of the present invention may contain one or more of the above-mentioned fruit juices, but from the viewpoint of effectiveness, it is preferable to contain grape juice, and more preferable to contain red grape juice.

[0020] In addition, the fermented milk product of the present invention may contain one or more kinds of fruit juices selected from the group consisting of purple taro juice and grape, orange, and blueberry juices. The mass ratio is not particularly limited, but in straight conversion, it is 1:0.1 to 1.5, preferably 1:0.3 to 1.3, and particularly preferably 1:0.7 to 1:1.3.

[0021] It is preferable to adjust the pH of the fermented milk product of the present invention. From the viewpoint of the discoloration suppression effect, it is more preferable to adjust the pH to 4.3 or less, and particularly preferably to 4.3 to 4.2. For this pH adjustment, organic acids generally used in foods may be used. Examples of such organic acids include malic acid, succinic acid, citric acid, tartaric acid, etc. These organic acids can be used alone or in combination of two or more, but it is preferable to use one or more selected from malic acid, citric acid, or tartaric acid, and it is more preferable to use malic acid because the decrease in flavor can be better suppressed.

[0022] Furthermore, the fermented milk product of the present invention may contain saccharides such as sucrose, glucose, and fructose, and it is preferable to contain sucrose from the viewpoint of flavor. The content of saccharides (excluding lactose derived from fermented milk) in the fermented milk product of the present invention is not particularly limited, but preferably 5% or more, and more preferably 6 to 10%.

[0023] Note that the above-mentioned organic acids and saccharides are excluded from those contained in purple taro juice or fruit juice (they are added separately).

[0024] The fermented milk product of the present invention can further be formulated with various commonly used food materials. For example, it may contain flavors, emulsifiers, vitamins, etc.

[0025] The fermented milk product of the present invention is not particularly limited in form, but it is preferable to contain a gelling agent such as gelatin, agar, pectin, xanthan gum, gellan gum, etc. for adjusting the hardness to make it a solid or semi-solid such as soft yogurt or hard yogurt. In such a form, fading during storage is likely to be noticeable, and the effect of suppressing fading of the present invention is likely to be exhibited. The content of the gelling agent in the fermented milk product of the present invention is not particularly limited, but for example, it is 0.2 to 1.0%, preferably 0.4 to 0.8%. Here, a solid refers to a state in which the shape does not change even when the container is tilted, and a semi-solid refers to a state in which the measured load by a rheometer is 100 g or more. A semi-solid has viscoelasticity but changes fluidly in form when the container is tilted, and a semi-solid refers to a state in which the measured load by a rheometer is less than 15 to 100 g. As a method for measuring the load, for example, it can be measured using a rheometer "COMPAC-100II" (manufactured by San Science Co., Ltd.) under the conditions of plunger: disk type φ30, stroke: 20 mm, and entering speed: 75 mm / min.

[0026] The fermented milk product of the present invention can be produced in the same manner as known fermented milk products, except that the above-mentioned purple sweet potato juice and fruit juice (and other organic acids, saccharides, gelling agents, flavors, etc. if necessary) are contained in fermented milk (fermented milk base) obtained by previously fermenting a medium with lactic acid bacteria. When the fermented milk product is solid or semi-solid, appropriate cooling or the like may be performed after containing the above-mentioned gelling agent.

[0027] The fermented milk used above is not particularly limited, but it is obtained by culturing a medium such as mammalian milk such as cow's milk, sheep's milk, goat's milk, skim milk obtained by defatting the above-mentioned mammalian milk, plant milk such as soy milk, and mixtures thereof with lactic acid bacteria by a known method.

[0028] In addition, since the fermented milk product of the present invention mixes purple sweet potato juice and fruit juice into fermented milk obtained by previously fermenting a medium with lactic acid bacteria, unlike the technology of Patent Document 1, the effect of the present invention is not particularly limited to the type of lactic acid bacteria. The fermented milk product of the present invention contains viable lactic acid bacteria.

[0029] Examples of lactic acid bacteria include Lacticaseibacillus species such as Lacticaseibacillus paracasei and Lacticaseibacillus casei, Lactobacillus gasseri, Lactobacillus acidophilus, Lactobacillus helveticus, Lactobacillus delbrueckii subsp. bulgaricus, Lactobacillus delbrueckii subsp. delbrueckii, and Lactobacillus johnsonii. Lactobacillus bacteria such as johnsonii, Ligilactobacillus salivarius, Limosilactobacillus fermentum, Liquorilactobacillus mali, Lactiplantibacillus plantarum, Streptococcus, Lactococcus subsp. lactis, Lactococcus lactis subsp. cremoris subsp.Examples of Lactococcus bacteria include Lactococcus species such as Lactococcus cremoris, Lactococcus plantarum, Lactococcus raffinolactis, and Lactococcus cremoris, as well as Enterococcus species such as Enterococcus faecalis and Enterococcus faecium. One or more of these lactic acid bacteria can be used.

[0030] The conditions for culturing lactic acid bacteria in the above medium are not particularly limited, but for example, the culture temperature is usually 20-50°C, preferably 25-40°C, and more preferably 30-38°C. The culture time is usually 6-62 hours, preferably 12-48 hours, and more preferably 15-30 hours. The fermentation method is not particularly limited, and a suitable method can be used from static fermentation, agitated fermentation, soaking fermentation, aeration fermentation, etc.

[0031] In this invention, discoloration of fermented dairy products can be suppressed by adjusting the pH of the fermented dairy product containing purple sweet potato juice and the above-mentioned fruit juice. Furthermore, discoloration of such fermented dairy products can also be suppressed by adjusting the pH of the fermented dairy product obtained by mixing fermented milk with anthocyanin-containing juice and / or anthocyanin-containing fruit juice to 4.3 or less.

[0032] Anthocyanin-containing juices and anthocyanin-containing fruit juices are not particularly limited as long as they contain anthocyanins. Examples of anthocyanin-containing juices include, in addition to the purple sweet potato juice mentioned above, juices from vegetables such as red perilla, purple cabbage, purple onion, and black beans. Examples of anthocyanin-containing fruit juices include, in addition to the grape and berry juices mentioned above, juices from fruits such as apples, peaches, cherries, plums, and prunes.

[0033] The content, manufacturing method, and method for adjusting the pH of fermented dairy products obtained by mixing fermented milk with anthocyanin-containing juice and / or anthocyanin-containing fruit juice are the same as those for fermented dairy products containing purple sweet potato juice and the above-mentioned fruit juice, as well as the method for adjusting their pH.

[0034] The fermented dairy product obtained in this way has improved flavor despite containing purple sweet potato juice.

[0035] Furthermore, the fermented dairy products of the present invention are superior in that they do not become excessively sour during storage, resulting in improved flavor, and color fading is suppressed during storage. Here, "during storage" refers to approximately 7 to 21 days at 4 to 10°C after the product is manufactured. Also, suppression of color fading means that the reddish-purple color derived from anthocyanins becomes lighter compared to before storage. [Examples]

[0036] The present invention will be described in detail below with reference to examples, but the present invention is not limited in any way to these examples.

[0037] Example 1 Types of fruit juices to combine with Ayamurasaki juice and their flavor evaluation: Sterilized 25% skim milk powder solution was inoculated with Streptococcus thermophilus (YIT 2001 strain) seed starter to a concentration of 0.2%, and then with Lacticaseibacillus paracasei (YIT 9029 strain) seed starter to a concentration of 0.1%. The mixture was cultured at 37°C to pH 4.5, and then homogenized at 15 MPa using a homogenizer to prepare 1000 g of fermented milk base. To 380g of this fermented milk base, 120g of sucrose-type liquid sugar (fine liquor: 67% sucrose content), 5g of powdered gelatin, 1.4g of powdered agar, and 494g of water were added and mixed in the amounts listed in Table 1 (straight equivalent): purple syrup juice, fruit juice (3.0% straight equivalent for clear lemon juice, 5.0% straight equivalent for other fruit juices), and water. The mixture was then placed in a designated container and cooled to produce a solid fermented milk product (pH 4.40). The flavor of the fermented milk product immediately after production was evaluated by five panelists according to the following criteria. The results are also shown in Table 1. All products exhibited a beautiful red color derived from the purple syrup juice.

[0038] [Table 1]

[0039] <Flavor Evaluation Criteria> (Rating) (Content) 5: Good 4: Fairly good 3: Neither agree nor disagree (tolerance limit) 2: Slightly bad 1: Bad

[0040] Table 1 shows that when purple berry juice was combined with grape, orange, or blueberry juice, the flavor harmonized better with the fermented dairy product than when purple berry juice was used alone, resulting in an improved flavor. Grape juice, especially red grape juice, showed a particularly noticeable improvement in flavor when combined with purple berry juice. However, in many cases, the flavor worsened when combined with purple berry juice depending on the type of juice.

[0041] Of the lactic acid bacteria used above, Streptococcus thermophilus (YIT 2001 strain) is internationally deposited as Streptococcus thermophilus YIT 2001 (FERM BP-7538, deposit date: January 31, 2001), and Lactobacillus paracasei (YIT 9029 strain) is internationally deposited as Lactobacillus casei YIT 9029 (FERM BP-1366, deposit date: May 1, 1981), at the Patent Organism Depository Center of the National Institute of Technology and Evaluation (2-5-8 Kazusa Kamatari, Kisarazu City, Chiba Prefecture, Japan 292-0818, Japan), which is the international depositary authority under the Budapest Convention. Previously, the Lactobacillus paracasei strain YIT 9029 was classified as Lactobacillus casei, but in recent years, the genus Lactobacillus has been reclassified, and it is now classified as Lactobacillus paracasei (Zheng et al., A taxonomic note on the genus Lactobacillus : Description of 23 novel genera, emended description of the genus Lactobacillus Beijerinck 1901, and union of Lactobacillaceae and Leuconostocaceae. Int. J. Syst. Evol. Microbiol. 2020 Apr; 70(4):2782-2858 DOI 10.1099 / ijsem.0.004107).

[0042] Example 2 Content and flavor evaluation of purple ginger juice and red grape juice: To 380g of the fermented milk base used in Example 1, 120g of sucrose-type liquid sugar, 5g of powdered gelatin, 1.4g of powdered agar, 494g of water, and the same amounts of purple ginger juice and red grape juice as in Example 1 (straight equivalent) as shown in Table 2 were added and mixed. The mixture was then placed in a designated container and cooled to produce a solid fermented milk product (pH 4.40). The flavor of this fermented milk product was evaluated on day 0 immediately after production, day 11 after production (stored at 10°C), and day 21 after production (stored at 10°C), as in Example 1. The results are also shown in Table 2.

[0043] [Table 2]

[0044] Fermented dairy products without red grape juice showed increased acidity after storage and the flavor of the purple grape juice did not match, resulting in significant flavor deterioration as the storage period lengthened. On the other hand, as shown in Table 2, when the mass ratio of purple grape juice to red grape juice was 1:0.35 to 1:1.28 (straight equivalent), flavor deterioration was suppressed even after 11 days of storage compared to products without red grape juice. Furthermore, it was found that a mass ratio of purple grape juice to red grape juice of 1:0.7 to 1:1.28 (straight equivalent) is preferable for suppressing flavor deterioration, especially for long-term storage. It should be noted that systems containing the same amount of purple grape juice showed similar increases in acidity after storage. Therefore, it was found that red grape juice does not affect the increase in acidity of fermented dairy products and only contributes to the flavor.

[0045] Implementation Example 3 Evaluation of discoloration and flavor due to pH adjustment: To 380g of the fermented milk base used in Example 1, 120g of sucrose-type liquid sugar, 5g of powdered gelatin, 1.4g of powdered agar, 494g of water, and the same amount of purple ginger juice (7.0% in straight equivalent) and red grape juice (7.1% in straight equivalent) as in Example 1 were added and mixed. Citric acid was added to adjust the pH to the value in Table 3, and the mixture was then placed in a designated container and cooled to produce a solid fermented milk product. The flavor of this fermented milk product was evaluated in the same manner as in Example 1. In addition, the discoloration of a semi-solid fermented milk product obtained by removing the powdered agar from the above formula was evaluated by five panelists on the 7th day after production according to the following criteria. The results are also shown in Table 3.

[0046] [Table 3]

[0047] <Evaluation Criteria for Fade Prevention Effect> (Rating) (Content) ◎: No fading observed ○: Slightly different △: Different enough to be perceived ×: Significantly different color

[0048] Table 3 shows that adjusting the product's pH to a level lower than the untreated pH of 4.4 improved discoloration, but lowering the pH too much impaired the flavor. Therefore, a pH of 4.2 to 4.3 was found to be preferable for the product.

[0049] Implementation Example 4 Types of organic acids and their flavor evaluation: To 380g of the fermented milk base used in Example 1, 120g of sucrose-type liquid sugar, 5g of powdered gelatin, 1.4g of powdered agar, 494g of water, and the same amounts of purple ginger juice and red grape juice as in Example 1 (straight equivalent) as listed in Table 4 were added and mixed. The pH was adjusted to 4.3 by adding the organic acids listed in Table 4, and then the mixture was cooled in a designated container to produce a solid fermented milk product. The flavor of this fermented milk product was evaluated on day 0 immediately after production, day 12 after production, and day 21 after production, as in Example 1. The results are shown in Table 4. In addition, the discoloration on day 7 after production was evaluated using a semi-solid fermented milk product obtained by removing the powdered agar from the above formula, according to the following criteria. The results are also shown in Table 4.

[0050] [Table 4]

[0051] Table 4 shows that all organic acids have a flavor-improving effect, but malic acid was found to be particularly preferable for long-term storage. In addition, all organic acids showed a similar discoloration effect.

[0052] Example 5 Sugar types and flavor evaluation: To 380g of the fermented milk base used in Example 1, 71-120g of sucrose-type liquid sugar, 0-44g of glucose-fructose liquid sugar, 5g of powdered gelatin, 1.4g of powdered agar, 494g of water, and the same amount of purple ginger juice (7.0% in straight equivalent) and red grape juice (7.1% in straight equivalent) as in Example 1 were added and mixed. Citric acid was added to adjust the pH to 4.3, and the mixture was then placed in a designated container and cooled to produce a solid fermented milk product. The flavor of this fermented milk product was evaluated on day 0 immediately after production, in the same manner as in Example 1. The results are shown in Table 5.

[0053] [Table 5]

[0054] Table 5 shows that using only sucrose as the sugar resulted in a greater improvement in flavor.

[0055] Implementation Example 6 Sucrose content and flavor evaluation: To 380g of the fermented milk base used in Example 1, 106-135g of sucrose liquid sugar, 5g of powdered gelatin, 1.4g of powdered agar, 479-508g of water, and the same amount of purple ginger juice (7.0% in straight equivalent) and red grape juice (7.1% in straight equivalent) as in Example 1 were added and mixed. Citric acid was then added to adjust the pH to 4.3, and the mixture was cooled in a designated container to produce a solid fermented milk product. The flavor of this fermented milk product was evaluated immediately after production, in the same manner as in Example 1. The results are shown in Table 6.

[0056] [Table 6]

[0057] Table 6 shows that a sucrose content of 7.6-8.1% is particularly preferable. [Industrial applicability]

[0058] This invention can be used to regularly consume functional components such as anthocyanins contained in purple sweet potato juice and functional components of fermented milk.

Claims

1. Contains 5 to 15% by mass of purple sweet potato juice on a straight basis, and purple sweet potato juice and A fermented dairy product characterized by containing one or more fruit juices selected from the group consisting of grapes and oranges in a ratio of 1:0.1 to 1.5 on a straight basis, and having a pH of 4.3 to 4.

2.

2. The fermented dairy product according to claim 1, wherein the purple sweet potato is Ayamurasaki.

3. The fermented dairy product according to claim 1 or 2, which contains one or more organic acids selected from the group consisting of malic acid, succinic acid, citric acid, and tartaric acid.

4. A fermented dairy product according to any one of claims 1 to 3, which contains malic acid.

5. A fermented dairy product according to any one of claims 1 to 4, which contains sucrose.

6. A fermented dairy product according to any one of claims 1 to 5, which is solid or semi-solid.

7. Fermented milk, purple sweet potato juice, The process of mixing purple sweet potato juice with one or more fruit juices selected from the group consisting of grapes and oranges, wherein the ratio of purple sweet potato juice to the fruit juices is 1:0.1 to 1.5 on a straight basis, and the pH is adjusted to 4.3 to 4.

2. A method for producing a fermented dairy product, characterized by containing [the specified ingredient].

8. Fermented dairy products containing purple sweet potato juice, A method for improving the flavor of a fermented dairy product, characterized by including one or more fruit juices selected from the group consisting of grapes and oranges in a ratio of 1:0.1 to 1.5 of the purple sweet potato juice and the fruit juices on a straight basis, and adjusting the pH to 4.3 to 4.

2.

9. Purple sweet potato juice and A method for suppressing discoloration of fermented dairy products, characterized by adjusting the pH of a fermented dairy product containing one or more fruit juices selected from the group consisting of grapes and oranges in a ratio of 1:0.1 to 1.5 of purple sweet potato juice and the fruit juices on a straight basis to 4.3 to 4.1.

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