JP7645645B2 - Solid yogurt with coenzyme Q10 - Google Patents

Description

The present invention relates to solid yogurt containing coenzyme Q10 and a method for producing the same.

Coenzyme Q10 is a component of the mitochondrial electron transport chain in human cells, and is involved in the production of ATP by acting as an electron carrier in oxidative phosphorylation reactions. Numerous research results have been reported showing that it is a substance that exhibits excellent pharmacological and physiological effects against various diseases. As a result, various foods containing coenzyme Q10 are being developed.

On the other hand, because yogurt is a soft food by structure, there are problems with the contents crumbling during transport by truck or handling, causing the yogurt's surface to lose its smoothness inside the container and causing pieces of the crumbled contents to adhere to the top lid.

Patent Document 1 describes a method for producing fermented milk, characterized in that the dissolved oxygen concentration in the fermented milk raw material mix at the start of fermentation is reduced by replacing it with an inert gas, and describes how this production method produces yogurt with a stable structure that is not broken by impacts during transportation.

JP 2005-176603 A

While we were investigating the production of yogurt with added coenzyme Q10, we found that when a large amount of coenzyme Q10 is added to yogurt, coenzyme Q10 rises to the surface of the yogurt because it is oil-soluble, and is oxidized and decomposed by oxygen in the upper space of the container, resulting in color unevenness due to coenzyme Q10. We also found that this problem becomes more pronounced when the yogurt is subjected to vibrations during transportation. Patent Document 1 discloses yogurt that has a hardness that makes it difficult to break when subjected to shocks during transportation, but does not take into consideration home delivery distribution, which requires a high level of transport resistance because the degree of shock applied during transportation is large and there are many opportunities for shock exposure, and the transport resistance is insufficient.

In view of the above problems, the object of the present invention is to provide a post-fermented solid yogurt containing coenzyme Q10, which has good uniform dispersion stability of coenzyme Q10, excellent transport resistance, and a texture that is acceptable for commercial use, preferably with a soft and smooth texture comparable to that of regular yogurt, and a method for producing the same.

As a result of intensive research by the inventors to solve the above problems, they discovered that in a post-fermented solid yogurt containing coenzyme Q10, by setting the content of coenzyme Q10 within a specific range, further blending agar so that the strength of the agar and the content of milk protein are each within a specific range, adjusting the pH of the yogurt to a specific range, and further controlling the median diameter of the yogurt particles to a specific size, it is possible to uniformly disperse and stabilize coenzyme Q10 while maintaining a texture that is acceptable for a product, and also to achieve good transport resistance, thereby completing the present invention.

That is, the first aspect of the present invention relates to a post-fermented solid yogurt containing Coenzyme Q10, which contains 0.02 to 0.3% by weight of Coenzyme Q10 in the whole yogurt and further contains agar, the strength (g weight %/ ^cm2 ) of the agar specified below and the milk protein content (weight %) being within an area (A) surrounded by straight lines connecting four points in Fig. 1 in order: Point A (60, 5.0), Point B (110, 4.7), Point C (110, 4.1), and Point D (70, 3.4), the pH of the yogurt is 4.1 to 4.7, and the median diameter of the yogurt particles is 50 to 100 µm.
Agar strength: jelly strength of the agar (g/cm ² )×addition amount of the agar in the whole yogurt (% by weight)
Preferably, the agar contains 0.07 to 0.175% by weight of agar having a jelly strength of 80 to 300 g/ ^cm2 based on the total weight of the yogurt, and 0.05 to 0.15% by weight of agar having a jelly strength of 500 to 950 g/ ^cm2 based on the total weight of the yogurt.
Preferably, the coenzyme Q10 is ubiquinol.
The second aspect of the present invention is a method for preparing a food product comprising the steps of: (a) providing a food product which contains 0.02 to 0.3% by weight of coenzyme Q10 in the entire raw material mix; and (b) further containing agar, and the strength of the agar as defined below (g·wt%/ ^cm2 1 ), and the milk protein content (wt%) is within the region (A) surrounded by the straight lines connecting the four points A (60, 5.0), B (110, 4.7), C (110, 4.1), and D (70, 3.4) in FIG. 1 in that order, homogenizing the raw material mix at a pressure of 10 to 20 MPa, sterilizing the raw material mix at 100 to 120°C for 1 to 60 seconds, adjusting the temperature to 40 to 46°C, adding lactic acid bacteria, filling the raw material mix into containers before the pH drops to 5.7, fermenting the raw material mix at 35 to 45°C until the pH reaches 4.4 to 4.85, and curing the raw material mix at 1 to 10°C for one day or more.
Agar strength: jelly strength of the agar (g/cm ² )×addition amount of the agar in the whole yogurt (% by weight)

According to the present invention, it is possible to provide a post-fermented solid yogurt containing coenzyme Q10, which has good uniform dispersion stability of coenzyme Q10, excellent transport resistance, and a texture that is acceptable for commercial use, preferably with a soft and smooth texture comparable to that of regular yogurt, and a method for producing the same.

1 is a graph showing preferred ranges of agar strength and milk protein content in a yogurt formulation according to one embodiment of the present invention. 1 is a graph showing more preferable ranges of agar strength and milk protein content in the formulation of a yogurt according to one embodiment of the present invention. 1 is a graph showing further preferred ranges of agar strength and milk protein content in the formulation of a yogurt according to one embodiment of the present invention.

Hereinafter, an embodiment of the present invention will be described in detail.
The yogurt according to the present embodiment is a post-fermented yogurt containing a specific amount of coenzyme Q10 and further containing agar, the strength of the agar and the content of milk protein each being within a specific range, and the pH of the yogurt and the median diameter of the yogurt particles each being within a specific range. Here, the post-fermented yogurt refers to a type of yogurt produced by adding lactic acid bacteria to a raw material mix, which is the raw material of the yogurt, filling it into a container, and then fermenting it (post-fermentation). The yogurt according to the present embodiment is not for drinking, but is provided as a so-called solid yogurt for eating.

The coenzyme Q10 is found in large amounts in humans and is a type of 2,3-dimethoxy-5-methyl-6-polyprenyl-1,4-benzoquinone with 10 isoprene units in the side chain. Oxidized and reduced forms of coenzyme Q10 are known, with the oxidized form being named "ubiquinone" and the reduced form being named "ubiquinol." In this embodiment, either ubiquinone or ubiquinol may be used as coenzyme Q10, or both may be used in combination, but from the standpoint of oral absorbability and bioavailability, it is preferable to use ubiquinol.

The content of coenzyme Q10 in the entire yogurt is preferably 0.02 to 0.3% by weight, more preferably 0.03 to 0.3% by weight, even more preferably 0.05 to 0.3% by weight, and particularly preferably 0.1 to 0.3% by weight. If the content of coenzyme Q10 is less than 0.02% by weight, the supplementation of coenzyme Q10 by eating yogurt may not be efficient. On the other hand, if the content is more than 0.3% by weight, the uniform dispersion stability of coenzyme Q10 in the yogurt may be poor.

The content of coenzyme Q10 can be measured, for example, as follows. First, mix and stir the yogurt thoroughly to make it uniform. In the case of yogurt in a cup, it can be easily homogenized by shaking it vigorously 200 to 300 times without opening the lid. 4 g of the homogenized yogurt is accurately weighed into a capped test tube, 10 mL of distilled water and 1 mL of saturated saline are added, and the mixture is sonicated for about 30 seconds to suspend the yogurt well until all lumps disappear. Next, 20 mL of ethanol and 20 mL of n-hexane are added, and the mixture is shaken at 200 rpm for 5 minutes in a shaker. For shaking, a shaker Model YS-8D manufactured by Yayoi Co., Ltd. is used, and it is preferable to shake in an arc. After shaking, the mixture is centrifuged at 2000 rpm for 2 minutes, and the supernatant is placed in a 100 mL eggplant flask and dried in an evaporator, and then sealed with nitrogen. When putting the mixture in the eggplant flask, it is important to use a Pasteur pipette to collect as much of the supernatant as possible. Also, when drying in an evaporator, be careful not to cause foaming or bumping. After suspending the test tube again by ultrasonic treatment for approximately 30 seconds, add 20 mL of n-hexane and shake in a shaker at 200 rpm for 5 minutes. Centrifuge at 2000 rpm for 2 minutes, place the supernatant in the 100 mL eggplant flask, dry in an evaporator, and then seal with nitrogen. Dissolve the contents of the eggplant flask in 5 mL of ethanol/n-hexane mixture (4:1) and transfer to a brown measuring flask. When transferring to the measuring flask, use a Pasteur pipette to transfer the entire amount.

The contents of the eggplant flask are dissolved again in 5 mL of ethanol/n-hexane mixture (4:1), transferred to the brown measuring flask, and ultrasonicated. Ethanol/n-hexane mixture (4:1) is added to make exactly 20 mL, and after thorough stirring, about 1 mL is filtered through a 0.45 μm filter and subjected to HPLC analysis. The HPLC conditions at this time are as follows: column: SYMMETRY C18 (Waters) 250 mm (length) 4.6 mm (inner diameter), mobile phase: C ₂ H ₅ OH: CH ₃ OH = 4:3 (v:v), detection wavelength: 210 nm, flow rate: 1 ml/min, retention time of reduced coenzyme Q10: 9.1 min, retention time of oxidized coenzyme Q10: 13.3 min.

The yogurt according to this embodiment contains milk protein. The milk protein means a protein contained in dairy products, and examples thereof include casein protein and whey protein. There are no particular limitations on the milk raw material that contains milk protein and is a source of milk protein, and examples thereof include buttermilk, cheese, cream cheese, concentrated whey, whey, raw milk, cow's milk, special cow's milk, partially skimmed milk, skim milk, processed milk, dairy beverage, concentrated milk, skim concentrated milk, unsweetened condensed milk, unsweetened condensed skim milk, sweetened condensed milk, sweetened condensed skim milk, fermented milk or powders thereof, whey protein concentrate (WPC), total milk protein, etc., and at least one selected from these groups may be used. Among these, raw milk, cow's milk, partially skimmed milk, skim milk, and skim milk powder are preferred from the viewpoint of flavor. Also, from the viewpoint of health consciousness, skim milk and skim milk powder, which have a low milk fat content, are preferred.

The yogurt according to this embodiment further contains agar. The agar is a polysaccharide obtained from red algae such as Tengusa (agar grass) and Gracilaria verum, and has a galactose skeleton. Only one type of agar may be used, or multiple types of agar with different jelly strengths may be used in combination.

In the yogurt according to this embodiment, the strength (g·wt%/ ^cm2 ) of the agar and the content (wt%) of the milk protein are preferably within the area (A) surrounded by the straight lines connecting the four points A (60, 5.0), B (110, 4.7), C (110, 4.1), and D (70, 3.4) in Fig. 1. Also, it is more preferable that they are within the area (B) surrounded by the straight lines connecting the four points E (67, 4.8), F (102, 4.6), G (102, 4.2), and H (74, 3.7) in Fig. 2. Furthermore, it is even more preferable that they are within the area (C) surrounded by the straight lines connecting the four points I (76, 4.5), J (91, 4.4), K (91, 4.3), and L (79, 4.0) in Fig. 3.

On the left side of the line connecting points A and D in Fig. 1, the uniform dispersion stability of coenzyme Q10 and the transport resistance of the yogurt may be poor, and the texture of the yogurt may be deteriorated. On the right side of the line connecting points A and D in Fig. 1, above the line connecting points A and B in Fig. 1, and on the left side of the line connecting points B and C in Fig. 1, i.e., in the range where the agar strength is 110 g·wt%/ ^cm2 or less, the texture of the yogurt may be deteriorated. On the right side of the line connecting points B and C in Fig. 1, i.e., in the region where the agar strength exceeds 110 g·wt%/ ^cm2 , the texture of the yogurt may be deteriorated. 1, below the line connecting the two points A and D in FIG. 1, and to the left of the line connecting the two points B and C in FIG. 1, i.e., in the range where the agar strength is 110 g·wt %/cm2 or ^less , the transport resistance of the yogurt may be poor and the texture of the yogurt may be deteriorated.

Here, the strength of the agar is represented by the product of the jelly strength (g/ ^cm2 ) of the agar added to the yogurt and the amount of the agar added (wt%) in the entire yogurt. When multiple types of agar with different jelly strengths are used in combination, the strength of each agar is calculated based on the jelly strength and the amount added of each agar, and the value obtained by adding up the respective strengths is regarded as the strength of the agar.

When only one type of agar is used as the agar, it is preferable that the agar having a jelly strength of 80 to 950 g/ ^cm2 is contained in an amount of 0.07 to 0.8 wt% based on the total weight of the yogurt. The content of the agar having a jelly strength of 80 to 950 g/ ^cm2 is more preferably 0.07 to 0.5 wt%, and even more preferably 0.1 to 0.3 wt%. When the content of the agar is within the above range, the uniform dispersion stability of coenzyme Q10 and the texture and transport resistance of the yogurt can be improved. The agar having a jelly strength of 80 to 950 g/ ^cm2 can be easily selected from agar having an average molecular weight of 60,000 to 500,000.

When using multiple types of agar with different jelly strengths in combination, it is preferable to use agar with low jelly strength and agar with high jelly strength in combination, and specifically, it is preferable that the yogurt contains 0.07 to 0.175% by weight of agar with a jelly strength of 80 to 300 g/ ^cm2 and 0.05 to 0.15% by weight of agar with a jelly strength of 500 to 950 g/ ^cm2 in the entire yogurt. The content of the agar with a jelly strength of 80 to 300 g/ ^cm2 is more preferably 0.08 to 0.15% by weight, and even more preferably 0.09 to 0.14% by weight. The content of the agar with a jelly strength of 500 to 950 g/ ^cm2 is more preferably 0.06 to 0.14% by weight, and even more preferably 0.07 to 0.12% by weight. When the content of each agar is within the above range, the uniform dispersion stability of coenzyme Q10 and the texture and transport resistance of the yogurt can be improved.

The agar having a jelly strength of 80 to 300 g/ ^cm2 can be easily selected from agars having an average molecular weight of 60,000 to 180,000, and the agar having a jelly strength of 500 to 950 g/ ^cm2 can be easily selected from agars having an average molecular weight of 200,000 to 500,000. Note that agars other than the above two types may be further contained within a range that satisfies the agar strength.

The jelly strength of agar can be measured by a known method, such as the Nikkansui method. Specifically, a 1.5% solution of agar is prepared, left to solidify at 20°C for 15 hours, and the maximum load (g) that the gel can withstand for 20 seconds per ^cm2 of its surface is determined. The average molecular weight of agar can be measured by a known method, such as gel permeation chromatography.

The coenzyme Q10-containing post-fermented solid yogurt according to this embodiment preferably has a pH of 4.1 to 4.7, more preferably 4.2 to 4.6, and even more preferably 4.3 to 4.6. If the pH is less than 4.1, the texture and flavor of the yogurt may be poor. If the pH is greater than 4.7, the transport resistance of the yogurt may be poor.

In the post-fermented solid yogurt containing coenzyme Q10 according to the present embodiment, the median diameter of the yogurt particles contained therein is preferably 50 to 100 μm, more preferably 54 to 90 μm, and even more preferably 54 to 85 μm. If the median diameter of the yogurt particles is smaller than 50 μm, the uniform dispersion stability of coenzyme Q10 may be poor. On the other hand, if it exceeds 100 μm, the texture of the yogurt may be deteriorated. The median diameter of the yogurt particles can be measured by a known method, and an example of the measurement method is a method using a laser diffraction/scattering type particle size distribution measurement device. In this case, water is used as the dispersion medium. An example of the laser diffraction/scattering type particle size distribution measurement device is the LA-960V2 (manufactured by Horiba, Ltd.). In addition, when measuring, the yogurt curd is taken without being broken and set in the measurement device as it is.

The yogurt according to this embodiment may contain other ingredients in addition to the coenzyme Q10, the agar, and the dairy ingredients including the milk protein, as long as the effects of the invention are not impaired. Examples of the other ingredients include carbohydrates, stabilizers, oils and fats, emulsifiers, flavorings, colorants, flavoring materials, antioxidants, etc.

The carbohydrate is not particularly limited, but examples thereof include sugar, fructose, glucose, starch syrup, reduced starch syrup, honey, isomerized sugar, invert sugar, oligosaccharides (isomaltooligosaccharides, reduced xylooligosaccharides, reduced gentiooligosaccharides, xylooligosaccharides, gentiooligosaccharides, nigerooligosaccharides, theanderoligosaccharides, soybean oligosaccharides, etc.), trehalose, sugar alcohols (maltitol, erythritol, sorbitol, reduced palatinose, xylitol, lactitol, etc.), and sugar-bound starch syrup (coupling sugar). At least one selected from these groups can be used.

Among these carbohydrates, sugar, fructose, glucose, starch syrup, reduced starch syrup, honey, isomerized sugar, invert sugar, and sugar alcohols (maltitol, erythritol, sorbitol, reduced palatinose, xylitol, lactitol, etc.) are preferred from the viewpoint of having a good sweetness.

In addition, from the viewpoint of low sugar content for health-conscious people, the sugars can be replaced with high-intensity sweeteners. The high-intensity sweeteners are not particularly limited, but examples include aspartame, alitame, monatin, licorice extract, sweet tea extract, Monk Fruit extract, saccharin, saccharin sodium, acesulfame potassium, sucralose, neotame, thaumatin, Monk Fruit extract, etc., and at least one selected from this group can be used. From the viewpoint of both good sweetness and low sugar content, it is preferable to use reduced palatinose and sucralose in combination.

The stabilizer is not particularly limited, but examples thereof include gum arabic, carrageenan, alginic acids (alginic acid, alginate), low methoxyl pectin (LM pectin), high methoxyl pectin (HM pectin), guar gum, tara gum, locust bean gum, tamarind seed gum, psyllium seed gum, water-soluble soybean polysaccharides, glucomannan, starch, modified starch, processed starch, dextrin, gellan gum, xanthan gum, pullulan, curdlan, cellulose, carboxymethylcellulose salt, methylcellulose, chitin, chitosan, gelatin, etc., and at least one selected from these groups can be used.

The oils and fats are not particularly limited as long as they are edible, but examples include various animal and vegetable oils and fats such as soybean oil, cottonseed oil, corn oil, safflower oil, olive oil, palm oil, rapeseed oil, rice bran oil, coconut oil, palm kernel oil, milk fat, lard, and fish oil, as well as processed oils and fats such as hardened oils, fractionated oils, and interesterified oils, and at least one selected from this group can be used.

The emulsifier is not particularly limited as long as it is edible, but examples thereof include monoglycerides, monoglyceride derivatives bound to organic acids, sucrose fatty acid esters, polyglycerol fatty acid esters, propylene glycol fatty acid esters, polyglycerol condensed ricinoleic acid esters, calcium stearoyl lactylate, and sodium stearoyl lactylate, and at least one selected from these groups can be used.

The flavoring agent is not particularly limited, and may be a natural or synthetic flavoring agent, such as yogurt flavor, fruit flavor, plant flavor, or a mixture thereof. Examples of the fruit flavor include citrus fruits such as lemon, orange, mandarin orange, grapefruit, shikuwasa, yuzu, and lime, strawberry, peach, grape, apple, pineapple, mango, melon, and banana, and at least one selected from these groups may be used.

The coloring agent is not particularly limited as long as it is edible, but examples include Monascus colorant, gardenia, lac, cochineal, carotene, etc., and at least one selected from this group can be used.

The flavoring material is not particularly limited as long as it is edible, and examples thereof include strawberries, peaches, mangoes, papayas, watermelons, melons, apples, persimmons, pears (including pears), bananas, loquats, pomegranates, lychees, plums, apricots, pineapples, grapes, kiwis, plums, Japanese apricots, cherries, passion fruit, blackcurrants, redcurrants; berries such as cranberries, blackberries, blueberries, and raspberries; citrus fruits such as oranges and grapefruits, aloe vera, and other fruits cut, pureed, or grated in the form of pulp, leaf pulp, seeds, or peel; and cut products such as jellies, agar gels, nata de coco, and almond tofu that imitate these fruits. At least one selected from these groups can be used.

The antioxidant is not particularly limited as long as it is edible, but examples include vitamin A, carotenoids, vitamin C, vitamin E, selenium, flavonoids, polyphenols, lycopene, lutein, lignans, etc., and at least one selected from this group can be used.

The post-fermented solid yogurt containing coenzyme Q10 according to this embodiment can be produced through a process of mixing and dissolving the raw materials, a homogenization process, a sterilization process, a process of adding lactic acid bacteria, a process of filling into containers, a fermentation process, and a curing process. Each process is described in detail below, but the method of producing the yogurt according to this embodiment is not limited to the description below.

(Mixing and dissolving process)
The above-mentioned raw materials for yogurt (i.e., coenzyme Q10, agar, milk raw materials containing milk protein, and other optional ingredients) are all mixed and dissolved to obtain a raw material mix. At this time, the coenzyme Q10 may be mixed simultaneously with other raw materials, but from the viewpoint of enhancing the uniform dispersion stability of coenzyme Q10, it is preferable to first prepare a mixed liquid by mixing and dissolving the raw materials other than coenzyme Q10, extract a part of the mixed liquid, add coenzyme Q10 to the extracted mixed liquid, mix and stir with a homomixer, and then mix and stir with the remaining mixed liquid. Since the melting point of coenzyme Q10 is about 50°C, it is preferable to adjust the temperature of the mixed liquid by mixing and dissolving the raw materials other than coenzyme Q10 to 50-70°C and add coenzyme Q10 thereto. The mixing and stirring conditions in the homomixer are preferably 80-250S ^-1 for 1-10 minutes, and more preferably 100-200S ^-1 for 3-7 minutes. When the stirring speed is 80 S ^-1 or more and the stirring time is longer than 1 minute, the uniform dispersion stability of coenzyme Q10 can be improved. However, when the stirring speed is faster than 200 S ^-1 or the stirring time is longer than 10 minutes, the effect may reach a plateau.

(Homogenization process)
The raw material mix obtained in the mixing and dissolving step is adjusted to a temperature of 50 to 70°C, and then homogenized to obtain a raw material mix after homogenization. The homogenization can be performed using a known homogenization device, and examples of such devices include, but are not limited to, a homogenizer, a microfluidizer, a colloid mill, and the like. The pressure during the homogenization is preferably 10 to 20 MPa, more preferably 12 to 20 MPa, and even more preferably 12 to 18 MPa. If the pressure during the homogenization is less than 10 MPa, the texture of the yogurt may feel rough, or the oil-soluble coenzyme Q10 may not be sufficiently finely divided, resulting in poor uniform dispersion stability of the coenzyme Q10. On the other hand, if the pressure exceeds 20 MPa, the oil droplets of the once finely divided coenzyme Q10 may break and coalesce with each other, resulting in poor uniform dispersion stability of the coenzyme Q10.

(Sterilization process)
The homogenized raw mix obtained in the homogenization step is sterilized at 100 to 120°C for 1 to 60 seconds to obtain a sterilized raw mix. The sterilization temperature is more preferably 105 to 120°C, and even more preferably 105 to 115°C. If the sterilization temperature is lower than 100°C, it may be difficult to obtain the effect of the sterilization treatment or the agar may not be sufficiently dissolved. On the other hand, if it exceeds 120°C, the protein may be thermally denatured and the smoothness of the yogurt may decrease. The sterilization time is more preferably 1 to 30 seconds, and even more preferably 1 to 15 seconds. If the sterilization time is shorter than 1 second, it may be difficult to obtain the effect of the sterilization treatment or the agar may not be sufficiently dissolved. On the other hand, if it is longer than 60 seconds, the protein may be thermally denatured and the smoothness of the yogurt may decrease.

(Step of adding lactic acid bacteria)
The raw material mix after sterilization obtained in the sterilization step is adjusted to a temperature of 40 to 46° C., the lactic acid bacteria are added, and the mixture is stirred to obtain a raw material mix after addition of the lactic acid bacteria. The adjusted temperature is more preferably 40 to 44° C., and even more preferably 40 to 42° C. If the adjusted temperature is outside the range of 40 to 46° C., the activity of the lactic acid bacteria decreases, which may result in a longer fermentation time or a worse flavor of the yogurt.

As the lactic acid bacteria, a lactic acid bacteria starter may be used. The lactic acid bacteria starter is not particularly limited, and those usually used in yogurt can be used. For example, lactic acid bacteria belonging to Lactococcus, Streptococcus, Pediococcus, and Leuconostoc, lactic acid bacteria belonging to Lactobacillus, and Bifidobacterium can be mentioned. Specific examples include Streptococcus thermophilus, Lactobacillus delbrueckii subsp. Bulgaricus, Lactobacillus acidophilus, and Bifidobacterium lactis.

The amount of lactic acid bacteria to be added is not particularly limited, but may be the amount normally used in making yogurt. For example, 0.00001 to 5 parts by weight may be added per 100 parts by weight of the total raw material mix. For freeze-dried types, 0.00001 to 0.05 parts by weight may be used, and for fermented liquid types, 0.01 to 5 parts by weight may be used.

(Container filling process)
The raw material mix after the addition of the lactic acid bacteria obtained in the lactic acid bacteria addition step is filled into a container before the pH of the raw material mix drops to 5.7 after the addition of the lactic acid bacteria, to obtain a raw material mix filled into a container. The pH at the time of filling is more preferably 6.1 or more, and even more preferably 6.3 or more. If the pH at the time of filling is less than 5.7, the formation of fermented curd may proceed before filling and may be destroyed during filling, resulting in whey separation or the like. The upper limit of the pH at the time of filling is not particularly limited, but may be, for example, 6.7 or less. To adjust the pH to the pH at the time of filling, the container may be filled within 2.5 hours after the addition of the lactic acid bacteria. The pH may be measured according to a conventional method, for example, using a pH meter ("F-52" manufactured by Horiba, Ltd.).

(Fermentation process)
The raw material mix filled in the container obtained in the filling step is fermented at 35 to 45°C until the pH reaches 4.4 to 4.85 to obtain a raw material mix after fermentation treatment. The fermentation temperature is more preferably 37 to 43°C, and even more preferably 38 to 42°C. If the fermentation temperature is outside the range of 35 to 45°C, the activity of the lactic acid bacteria decreases, which may result in a long fermentation time or a deterioration in the flavor of the yogurt obtained after the cooling step described below. The pH at the end of the fermentation is more preferably 4.5 to 4.8. If the pH at the end of the fermentation is less than 4.4, the flavor and texture of the yogurt obtained after the cooling step may be deteriorated. On the other hand, if the pH is higher than 4.85, the flavor of the yogurt obtained after the cooling step may be insufficient. To adjust the pH at the end of the fermentation to within the above range, the retention time at the fermentation temperature may be, for example, about 5 to 10 hours.

(Curing process)
The yogurt according to the present embodiment can be obtained by curing the raw material mix after the fermentation treatment obtained in the fermentation step at 1 to 10°C for one day or more. The temperature during the curing is more preferably 1 to 8°C, and even more preferably 1 to 6°C. If the temperature during the curing is lower than 1°C, the yogurt may freeze, which may deteriorate the uniform dispersion stability of coenzyme Q10. On the other hand, if the temperature is higher than 10°C, the hygienic shelf life may decrease. From a hygienic standpoint, the number of days for curing is preferably 21 days or less.

The yogurt manufacturing method described above allows the production of post-fermented solid yogurt that has good uniform dispersion stability of coenzyme Q10, excellent transport resistance, and a texture that is acceptable for commercial use, preferably with a softness and smooth texture comparable to that of regular yogurt.

The present invention will be explained in more detail with reference to the following examples, but the present invention is not limited to these examples. Note that in the examples, "parts" and "%" are by weight.

The raw materials used in the examples and comparative examples are as follows.
1) Kaneka skim milk powder (milk protein content: 34.0%) manufactured by Kaneka Corporation
2) "Ina Agar SY-6" manufactured by Ina Agar Co., Ltd. (jelly strength: 630 g/cm ² , average molecular weight: 270,000)
3) San-Ei Gen F.F.I. Co., Ltd. "Sunsweet SU-100" (15% sucralose, 85% reduced palatinose)
4) Kaneka QH (reduced coenzyme Q10) manufactured by Kaneka Corporation
5) “MPC80 SOLMIKO” manufactured by Glanbia Nutritionals (milk protein content: 80.5%)
6) "Ultra Agar AX-200" manufactured by Ina Agar Co., Ltd. (jelly strength: 200 g/cm ² , average molecular weight: 110,000)
7) Kaneka Corporation "Kaneka Q10" (oxidized coenzyme Q10)
8) "AP-50F" manufactured by Nippi Corporation
9) "Smart Taste" by San-Ei Gen F.F.I. Co., Ltd.
10) "UNIPECTINE LMSN325 CITRUS" manufactured by Unitech Foods Co., Ltd.

<Measurement of median diameter of yogurt particles>
The median diameter of the yogurt particles was measured by taking a sample from the yogurt curd without breaking it, and using a laser diffraction/scattering type particle size distribution measuring device LA-960V2 (manufactured by Horiba, Ltd.) with water as a dispersion medium.

<Measurement of pH of yogurt>
The pH of the yogurt was measured using a pH meter ("F-52" manufactured by Horiba, Ltd.).

<Method for measuring coenzyme Q10 content>
4 g of yogurt was accurately weighed into a capped test tube, 10 mL of distilled water and 1 mL of saturated saline were added, and the mixture was suspended by ultrasonic treatment for about 30 seconds. 20 mL of ethanol and 20 mL of n-hexane were added, and the mixture was shaken for 5 minutes at 200 rpm in a shaker. Centrifugation was performed for 2 minutes at 2000 rpm, and the supernatant was placed in a 100 mL eggplant flask, dried in an evaporator, and then sealed with nitrogen. The test tube was again suspended by ultrasonic treatment for about 30 seconds, and 20 mL of n-hexane was added, and the mixture was shaken for 5 minutes at 200 rpm in a shaker. Centrifugation was performed for 2 minutes at 2000 rpm, and the supernatant was placed in the 100 mL eggplant flask, dried in an evaporator, and then sealed with nitrogen. The contents of the eggplant flask were dissolved in 5 mL of ethanol/n-hexane mixture (4:1) and transferred to a brown measuring flask. The contents of the recovery flask were dissolved again in 5 mL of ethanol/n-hexane mixture (4:1), transferred to the brown measuring flask, and subjected to ultrasonic treatment. An ethanol/n-hexane mixture (4:1) was added to make exactly 20 mL, and about 1 mL of the mixture was filtered through a 0.45 μm filter and subjected to HPLC analysis.

(HPLC conditions)
Analytical column: SYMMETRY C18 (Waters) 250 mm (length) 4.6 mm (inner diameter)
Mobile phase: _{C2H5OH : CH3OH} =4:3 (v:v)
Detection wavelength: 210 nm
Flow rate: 1ml/min
Retention time of reduced coenzyme Q10: 9.1 min
Oxidized coenzyme Q10 retention time: 13.3 min

<Yogurt evaluation>
(Uniform dispersion stability of coenzyme Q10)
The top lids of the yogurt cups obtained in the Examples and Comparative Examples were removed, and the coenzyme Q10 content (X) in the yogurt within about 10 mm from the surface and the coenzyme Q10 content (Y) in the yogurt within about 10 mm from the bottom of the container (about 27 to 37 mm from the surface of the yogurt) were measured, and the uniform dispersion stability was calculated using the following formula.
Uniform dispersion stability (%) = [{(X)-(Y)}/{(X)+(Y)}/2]×100

Measurements were carried out on five pieces for each Example or Comparative Example, and evaluation was carried out based on the average value. The evaluation criteria at that time were as follows:
5 points: uniform dispersion stability is less than 5% 4 points: uniform dispersion stability is 5% or more but less than 10% 3 points: uniform dispersion stability is 10% or more but less than 15% 2 points: uniform dispersion stability is 15% or more but less than 25% 1 point: uniform dispersion stability is 25% or more

(Transportation durability of yogurt)
Ten pieces of each yogurt obtained in the Examples and Comparative Examples, which were 6 days after production, were packed in a cardboard box with 2 pieces vertically and 5 pieces horizontally so as to have no gaps, and were transported by refrigerated home delivery from Kaneka Takasago Industrial Works (Takasago City, Hyogo Prefecture) to Kaneka Tokyo Head Office (Akasaka, Minato Ward, Tokyo). Immediately after arrival, the cup was tilted at a 45 degree angle, and the degree of crumbling was evaluated by an experienced panelist according to the following criteria. The transportation test was carried out five times on different days, and the average score was used as the evaluation score.
5 points: Much better than the yogurt of Example 2, no deformation or syneresis, and extremely good transport resistance. 4 points: Better than the yogurt of Example 2, no deformation or syneresis, and good transport resistance. 3 points: Equivalent to the yogurt of Example 2, almost no deformation or syneresis, and good transport resistance. 2 points: Worse than the yogurt of Example 2, some deformation and syneresis, and poor transport resistance. 1 point: Much worse than the yogurt of Example 2, very severe deformation and syneresis, and no transport resistance.

(The texture of yogurt)
A sensory evaluation was carried out by having 10 experienced panelists taste the yogurts obtained in the Examples and Comparative Examples, which had been adjusted to 10° C., and the average of the scores was regarded as the sensory evaluation. The evaluation criteria were as follows:
5 points: better than the yogurt of Example 13, extremely good softness and smoothness, and comparable to general yogurt ("Megumi Lactobacillus gasseri SP strain yogurt" manufactured by Megmilk Snow Brand Co., Ltd., the same below); 4 points: equivalent to the yogurt of Example 13, good softness and smoothness, but slightly inferior to general yogurt; 3 points: slightly worse than the yogurt of Example 13, slightly worse softness and smoothness, and inferior to general yogurt, but at a level that is acceptable as a product; 2 points: worse than the yogurt of Example 13, not much softness and smoothness, and worse than general yogurt; 1 point: much worse than the yogurt of Example 13, no softness or smoothness at all, and clearly worse than general yogurt;

(comprehensive evaluation)
A comprehensive evaluation was made based on the evaluation results of the uniform dispersion stability of coenzyme Q10, the durability during transportation, and the texture of the yogurt. The evaluation criteria were as follows:
A: Coenzyme Q10 uniform dispersion stability, transport resistance, and texture all satisfy 4.0 points or more and 5.0 points or less. B: Coenzyme Q10 uniform dispersion stability, transport resistance, and texture all satisfy 3.5 points or more and 5.0 points or less, with at least one being 3.5 or more and less than 4.0. C: Coenzyme Q10 uniform dispersion stability, transport resistance, and texture all satisfy 3.0 points or more and 5.0 points or less, with at least one being 3.0 or more and less than 3.5. D: Coenzyme Q10 uniform dispersion stability, transport resistance, and texture all satisfy 2.0 points or more and 5.0 points or less, with at least one being 2.0 or more and less than 3.0. E: Coenzyme Q10 uniform dispersion stability, transport resistance, and texture all satisfy less than 2.0 points.

(Example 1) Preparation of yogurt A raw material mix was prepared by adding and dissolving 14.5 parts by weight of skim milk powder, 0.10 parts by weight of agar A, 0.05 parts by weight of sweetener, and 85.21 parts by weight of water. 3 parts by weight of the raw material mix was removed, and 0.14 parts by weight of reduced coenzyme Q10 was added, and the mixture was stirred for 5 minutes at 160S ^-1 using a homomixer, and the solution was added to the remaining raw material mix. The obtained raw material mix was preheated to 60°C, homogenized at a pressure of 14 MPa using a high-pressure homogenizer, heated to 110°C using a plate-type heat exchanger, and held for 2 seconds to perform sterilization treatment. Then, the mixture was cooled to 40°C, and 0.0176 parts by weight of lactic acid bacteria starter (Streptococcus thermophilus, Lactobacillus delbrueckii subsp. Bulgaricus, Lactobacillus acidophilus, Bifidobacterium lactis) was added. After stirring for 10 minutes, 90 g was filled into a container (cylindrical shape with upper diameter: 64.4 mm, bottom diameter: 50.6 mm, height: 54.4 mm). The pH of the raw material mix when filled into the container was 6.5. After fermentation at 40°C until the pH reached 4.7, the mixture was transferred to a refrigerator at 4°C for cooling, and then aged at that temperature for 7 days to produce yogurt. The results of the pH of the obtained yogurt, the median diameter of the yogurt particles, the uniform dispersion stability of coenzyme Q10, the transport resistance, and the texture are shown in Table 1.

(Examples 2 to 8) Preparation of Yogurt According to the formulation in Table 1, in Example 1, 14.5 parts by weight of skim milk powder and 0.10 parts by weight of agar A were changed to 10.4 parts by weight and 0.11 parts by weight (Example 2), 12.0 parts by weight and 0.12 parts by weight (Example 3), 13.2 parts by weight and 0.12 parts by weight (Example 4), 12.7 parts by weight and 0.13 parts by weight (Example 5), 14.0 parts by weight and 0.15 parts by weight (Example 6), 12.0 parts by weight and 0.17 parts by weight (Example 7), or 13.7 parts by weight and 0.17 parts by weight (Example 8), respectively, and yogurt was prepared in the same manner as in Example 1, except that the total amount was adjusted with water. The results of the pH of the obtained yogurt, the median diameter of the yogurt particles, the uniform dispersion stability of coenzyme Q10, the transport resistance, and the texture are shown in Table 1.

As is clear from Table 1, the yogurts of Examples 1 to 8, whose agar strength and milk protein content were within the range of region (A) in Figure 1, were evaluated as having good uniform dispersion stability of coenzyme Q10, resistance to transport, and texture. In particular, the yogurts of Examples 3 to 5, which were within the range of region (B) in Figure 2, were evaluated as having better uniform dispersion stability, resistance to transport, and texture. In particular, the yogurt of Example 5, which was within the range of region (C) in Figure 3, was evaluated as having even better uniform dispersion stability, and texture.

(Comparative Examples 1 to 6) Preparation of Yogurt According to the formulations in Table 2, in Example 1, 14.5 parts by weight of skim milk powder and 0.10 parts by weight of agar A were changed to 11.0 parts by weight and 0.08 parts by weight (Comparative Example 1), 9.0 parts by weight and 0.10 parts by weight (Comparative Example 2), 15.3 parts by weight and 0.10 parts by weight (Comparative Example 3), 9.5 parts by weight and 0.15 parts by weight (Comparative Example 4), 11.7 parts by weight and 0.18 parts by weight (Comparative Example 5), or 14.4 parts by weight and 0.18 parts by weight (Comparative Example 6), respectively, and yogurt was prepared in the same manner as in Example 1, except that the total amount was adjusted with water. The results of the pH of the obtained yogurt, the median diameter of the yogurt particles, the uniform dispersion stability of coenzyme Q10, the transport resistance, and the texture are shown in Table 2.

As is clear from Table 2, the yogurts of Comparative Examples 1 to 6, whose agar strength and milk protein content were not within the range of region (A) in Figure 1, were inferior in at least one of the evaluations of transport resistance and texture.

(Example 9) Preparation of Yogurt Yogurt was prepared in the same manner as in Example 5, except that the amount of skim milk powder in Example 5 was changed from 12.7 parts by weight to 9.5 parts by weight, 1.5 parts by weight of milk protein was added, and the total amount was adjusted with water according to the formulation in Table 3. The results of the pH of the obtained yogurt, the median size of the yogurt particles, the uniform dispersion stability of coenzyme Q10, the transport resistance, and the texture are shown in Table 3.

As is clear from Table 3, the yogurt of Example 9, which had a different type of milk protein, had good evaluations of the uniform dispersion stability of coenzyme Q10, transport resistance, and texture, similar to the yogurt of Example 5.

(Example 10) Preparation of Yogurt Yogurt was prepared in the same manner as in Example 5, except that the amount of agar A in Example 5 was changed from 0.13 parts by weight to 0.10 parts by weight, 0.10 parts by weight of agar B was further added, and the total amount was adjusted with water according to the formulation in Table 3. The results of the pH of the obtained yogurt, the median size of the yogurt particles, the uniform dispersion stability of coenzyme Q10, the transport resistance, and the texture are shown in Table 3.

As is clear from Table 3, the yogurt of Example 10, which used two types of agar, agar B having a jelly strength in the range of 80 to 300 g/ ^cm2 and agar A having a jelly strength in the range of 500 to 950 g/ ^cm2 , had good evaluations for the uniform dispersion stability of coenzyme Q10, transport resistance, and texture, and was superior to the yogurt of Example 5 in terms of transport resistance and texture.

(Example 11) Preparation of Yogurt Yogurt was prepared in the same manner as in Example 5, except that the reduced coenzyme Q10 in Example 5 was changed from 0.14 parts by weight to 0.30 parts by weight, and the total amount was adjusted with water, according to the formulation in Table 3. The results of the pH of the obtained yogurt, the median size of the yogurt particles, the uniform dispersion stability of coenzyme Q10, the transport resistance, and the texture are shown in Table 3.

As is clear from Table 3, the yogurt of Example 11, which contains a high amount of reduced coenzyme Q10 at 0.30% by weight, was evaluated as being good in terms of the uniform dispersion stability of coenzyme Q10, transport resistance, and texture, similar to that of Example 5.

(Example 12) Preparation of Yogurt Yogurt was prepared in the same manner as in Example 5, except that reduced coenzyme Q10 in Example 5 was changed to oxidized coenzyme Q10 according to the formulation in Table 3. The results of the pH of the obtained yogurt, the median size of the yogurt particles, the uniform dispersion stability of coenzyme Q10, the transport resistance, and the texture are shown in Table 3.

As is clear from Table 3, the yogurt of Example 12, to which oxidized coenzyme Q10 was added, had good evaluations of the uniform dispersion stability of coenzyme Q10, transport resistance, and texture, similar to those of Example 5.

(Comparative Examples 7 to 9) Preparation of Yogurt Yogurt was prepared in the same manner as in Example 10, except that 0.1 part by weight of agar A and 0.1 part by weight of agar B in Example 10 were changed to 0.2 part by weight of gelatin (Comparative Example 7), 0.3 part by weight of dextrin (Comparative Example 8), or 0.13 part by weight of pectin (Comparative Example 9) in accordance with the formulation in Table 4, and the total amount was adjusted with water. The results of the pH of the obtained yogurt, the median size of the yogurt particles, the uniform dispersion stability of coenzyme Q10, the transport resistance, and the texture are shown in Table 4.

As is clear from Table 4, the yogurt with added gelatin (Comparative Example 7), the yogurt with added dextrin (Comparative Example 8), and the yogurt using pectin (Comparative Example 9) all had poor evaluations of the uniform dispersion stability and transport resistance of coenzyme Q10.

(Examples 13 to 14 and Comparative Example 10) Preparation of Yogurt Yogurt was prepared in the same manner as in Example 10, except that the pH at the end of fermentation in Example 10 was changed from 4.7 to pH 4.4 (Example 13), pH 4.85 (Example 14), or pH 5.0 (Comparative Example 10) according to the formulation in Table 5. The results of the pH of the obtained yogurt, the median size of the yogurt particles, the uniform dispersion stability of coenzyme Q10, the resistance to transportation, and the texture are shown in Table 5.

As is clear from Table 5, the yogurt of Example 13 (pH 4.1) and the yogurt of Example 14 (pH 4.7), both of which have a pH in the range of 4.1 to 4.7, were evaluated as being good in terms of uniform dispersion stability of coenzyme Q10, transport resistance, and texture. On the other hand, the yogurt of Comparative Example 10, which has a high pH of 4.8, was evaluated as being poor in terms of transport resistance.

(Example 15) Preparation of yogurt Yogurt was prepared in the same manner as in Example 10, except that the pH at the time of filling the container was changed from 6.5 to 5.7, according to the formulation in Table 5. The results of the pH of the obtained yogurt, the median size of the yogurt particles, the uniform dispersion stability of coenzyme Q10, the resistance to transportation, and the texture are shown in Table 5.

As is clear from Table 5, the yogurt (Example 15) obtained by changing the pH when filled into the container was evaluated to be good in terms of uniform dispersion stability of coenzyme Q10, resistance to transportation, and texture.

Claims (4)

The yogurt contains 0.02 to 0.3% by weight of coenzyme Q10.
Further containing agar,
The strength (g·wt%/ ^cm2 ) of the agar and the milk protein content (wt%) defined below are within an area (A) surrounded by straight lines sequentially connecting four points in FIG. 1: point A (60, 5.0), point B (110, 4.7), point C (110, 4.1), and point D (70, 3.4);
The pH of the yogurt is 4.1 to 4.7,
A post-fermented solid yogurt containing coenzyme Q10, the median diameter of the yogurt particles being 50 to 100 μm.
Agar strength: jelly strength of the agar (g/cm ² )×addition amount of the agar in the whole yogurt (% by weight) The coenzyme Q10-containing post-fermented solid yogurt according to claim 1, wherein the agar contains 0.07 to 0.175% by weight of agar having a jelly strength of 80 to 300 g/ ^cm2 based on the total weight of the yogurt, and 0.05 to 0.15% by weight of agar having a jelly strength of 500 to 950 g/ ^cm2 based on the total weight of the yogurt. The post-fermented solid yogurt containing coenzyme Q10 according to claim 1 or 2, wherein the coenzyme Q10 is ubiquinol. A method for producing a post-fermented solid yogurt containing coenzyme Q10, comprising the steps of: homogenizing a raw material mix containing 0.02-0.3 wt% coenzyme Q10 in the entire raw material mix; further containing agar; and the strength (g wt%/ ^cm2 ) of the agar and the milk protein content (wt%) of which are within an area (A) surrounded by straight lines connecting four points A (60, 5.0), B (110, 4.7), C (110, 4.1), and D (70, 3.4) in Fig. 1 in that order, at a pressure of 10-20 MPa; sterilizing the raw material mix at 100-120°C for 1-60 seconds; adjusting the temperature to 40-46°C; adding lactic acid bacteria; filling the mixture into a container before the pH drops to 5.7; fermenting the mixture at 35-45°C until the pH reaches 4.4-4.85; and curing the mixture at 1-10°C for one day or more.
Agar strength: jelly strength of the agar (g/cm ² )×addition amount of the agar in the whole yogurt (% by weight)

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