Fermented-milk-containing frozen dessert and method for producing fermented-milk-containing frozen dessert

Abstract

Provided is a fermented-milk-containing frozen dessert in which overrun is not more than 80%, and in which the median value of the diameter of ice crystals is not more than 60 μm. Also provided is a method for producing a fermented-milk-containing frozen dessert comprising: a step for mixing fermented milk and a frozen dessert ingredient other than fermented milk to obtain an ingredient liquid; a step for freezing the ingredient liquid to obtain partially frozen matter; a step for molding the partially frozen matter; and a step for hardening the molded partially frozen matter. In the step for freezing the ingredient liquid, overrun of the partially frozen matter is not more than 80%. In the step for molding the partially frozen matter, the temperature of the partially frozen matter is not lower than 1°C below the freezing point of the partially frozen matter but is lower than the freezing point.

Description

Frozen dessert containing fermented milk and method for producing frozen dessert containing fermented milk

[0001] This invention relates to a frozen dessert containing fermented milk and a method for producing a frozen dessert containing fermented milk. This application claims priority to Japanese Patent Application No. 2025-012620, filed in Japan on January 29, 2025, the contents of which are incorporated herein by reference.

[0002] Generally, when liquid fermented milk is frozen, the acid in the fermented milk causes coagulation of milk proteins, and relatively large ice crystals tend to form. Patent Document 1 proposes that in order to produce frozen yogurt with a pleasant texture, liquid yogurt fermented to pH 4.0 to 4.5 is instantly dried and powdered, sugars and stabilizers are added to the resulting powder, the resulting raw material powder is mixed and dissolved with a preparation liquid, and then frozen in a freezer.

[0003] Japanese Patent Application Publication No. 1-211447

[0004] However, currently, frozen yogurt has a crunchy texture, not the smooth texture of ice cream. The present invention aims to provide a fermented milk-containing frozen dessert with superior smoothness of texture and a method for producing the same.

[0005] The present invention has the following embodiments: [1] A frozen dessert containing fermented milk, wherein the overrun is 80% or less and the median diameter of the ice crystals is 60 μm or less. [2] The frozen dessert containing fermented milk according to [1], which is frozen yogurt. [3] The frozen dessert containing fermented milk according to [1] or [2], which contains a propylene glycol fatty acid ester. [4] The frozen dessert containing fermented milk according to any one of [1] to [3], wherein the fermented milk content is 60 to 80% by mass of the total mass of the frozen dessert containing fermented milk. [5] The frozen dessert containing fermented milk according to any one of [1] to [4], which contains Bifidobacterium bacteria. [6] A method for producing a frozen dessert containing fermented milk, comprising the steps of: mixing fermented milk with frozen dessert ingredients other than the fermented milk to obtain a raw material liquid; freezing the raw material liquid to obtain a partially frozen product; shaping the partially frozen product; and hardening the shaped partially frozen product, wherein in the step of freezing the raw material liquid, the overrun of the partially frozen product is 80% or less; and in the step of shaping the partially frozen product, the temperature of the partially frozen product is set to be 1°C or higher and below the freezing point of the partially frozen product. [7] The method for producing a frozen dessert containing fermented milk according to [6], wherein the frozen dessert containing fermented milk is frozen yogurt. [8] The method for producing a frozen dessert containing fermented milk according to [6] or [7], wherein the frozen dessert ingredients include propylene glycol fatty acid ester. [9] The method for producing a frozen dessert containing fermented milk according to any one of [6] to [8], wherein the content of the fermented milk is 60 to 80% by mass of the total mass of the raw material liquid.

[10] A method for producing a frozen dessert containing fermented milk according to any one of [6] to [9], wherein at least one of the fermented milk and the frozen dessert ingredients contains bacteria of the genus Bifidobacterium.

[0006] According to the present invention, it is possible to provide a fermented milk-containing frozen dessert with excellent smooth texture and a method for producing the same.

[0007] This diagram schematically shows a graph obtained by measuring the texture of typical frozen yogurt. This diagram schematically shows a graph obtained by measuring the texture of typical ice cream.

[0008] In this specification, the following definitions apply. In frozen desserts containing fermented milk, "frozen dessert" includes those generally classified as "frozen desserts" and frozen yogurt. Specifically, "frozen dessert" can refer to ice cream products (e.g., ice cream, ice milk, and lacto ice). Ice cream products refer to products made by processing milk or foods made from milk or milk as raw materials, or by freezing products that use milk or milk as the main raw material, and that contain 3.0% or more milk solids (excluding fermented milk). Ice cream products are classified into three types: ice cream, ice milk, and lacto ice, depending on the amount of milk solids and milk fat they contain. Frozen yogurt is classified as "fermented milk" by type according to the Order Concerning Standards for Ingredients of Milk and Dairy Products. Fermented milk is defined as "a product made by fermenting milk or milk containing an equivalent or greater amount of non-fat milk solids with lactic acid bacteria or yeast, and making it into a paste or liquid, or by freezing these," and the ingredient standard is specified as "8.0% or more non-fat milk solids, and 10 million or more lactic acid bacteria or yeasts per mL." Frozen yogurt is a type of frozen fermented milk. The fermented milk-containing frozen dessert in this invention may be ice cream, ice milk, lacto ice, or frozen yogurt. Preferably, it is ice milk or frozen yogurt, and particularly preferably frozen yogurt. Therefore, it is especially preferable that the fermented milk-containing frozen dessert in this invention meets the component standards for fermented milk.

[0009] "Overrun" is the percentage of the volume of air contained relative to the volume before air was added. For example, if the overrun is 100%, it contains the same volume of air as before air was added. "Freezing point" is the temperature at which the temperature of a liquid sample stops decreasing due to the exothermic reaction when the liquid turns into a solid (i.e., the freezing point) when the sample temperature is measured over time while the liquid sample is cooled at an ambient temperature of -25°C. "Freezing" means the process of increasing ice crystals while stirring at a low temperature. "Partially frozen material" means a material that contains ice crystals and is fluid. "Hardening" means a state in which water freezes and loses its fluidity. Unless otherwise specified, numerical ranges represented by "~" mean a numerical range with the values ​​before and after "~" as the lower and upper limits, and also mean a numerical range that includes the lower and upper limits.

[0010] The diameter of an ice crystal is the equivalent circular diameter of the ice crystal in the image observed with an optical microscope. The median diameter of the ice crystals is the median diameter. The average diameter of the ice crystals is the arithmetic mean diameter. The number of ice crystals that can be observed within the field of view of the optical microscope and the area of ​​all ice crystals are measured, and the diameter (equivalent circular diameter) of each ice crystal is calculated using the formula: diameter = 2 × √(measured area / π). For the measurement, the frozen dessert is preheated by storing it in a temperature-controlled cabinet at -15°C for at least 4 hours, and an optical microscope that has been temperature-controlled in a -15°C environment is used. If the number of ice crystals observed in one field of view is less than 100, the number of fields of view is increased until the total number of ice crystals exceeds 100. The median diameter of each ice crystal's diameter is used as the median value, and the arithmetic mean diameter is used as the average value.

[0011] The following methods are used to measure the content of components, etc. (1) Moisture content is measured by atmospheric pressure heating and drying method (with drying aid). Specifically, 1 g of the sample is dried for 3 hours at atmospheric pressure at a drying temperature of 98 to 100°C using purified silica sand as a drying aid, then cooled in a desiccator for 30 minutes and weighed. Drying, cooling, and weighing are repeated until a constant weight is reached, and the moisture content is calculated using the following formula: Moisture content (mass%) = Loss on drying (g) / Sample amount (g) × 100 (2) Solid content The moisture content percentage (mass%) of the sample is calculated from the above moisture content, and the solid content can be calculated using the following formula: Solid content (mass%) = 100 - Moisture (mass%)

[0012] (3) Fat content and milk fat content The milk fat content of ice cream is measured in accordance with the method for determining the milk fat content of ice cream products as described in the "Order Concerning Standards for Ingredients of Milk and Dairy Products." Specifically, 4 g of the sample is placed in a small beaker, 3 mL of water is added and mixed well, and then transferred to a Roerrich tube. The beaker is thoroughly washed with 3 mL of water, and the washings are added to the Roerrich tube and shaken. Next, 2 mL of ammonia water (a 25-30% aqueous solution of ammonia, colorless and transparent) is added and mixed gently. Next, the Roerrich tube is placed in a 60°C water bath and heated for 20 minutes while shaking occasionally. Further, 10 mL of ethanol (a 95-96% aqueous solution) is added and mixed well. Then, 25 mL of ether is added to the Roerrich tube and rotated gently until a uniform color is achieved, then the ether gas is released, the tube is held horizontally and shaken vigorously for 30 seconds. Next, add 25 mL of petroleum ether (boiling point below 60°C), shake for 30 seconds as before, loosen the stopper, and let it stand upright for at least 2 hours until the supernatant becomes clear. Pour the supernatant into a beaker whose constant weight has been determined beforehand. Add 25 mL of ether and 25 mL of petroleum ether to the Roerrich tube in the same procedure as above and mix, then pour the supernatant into the beaker. Wash the tip of the side tube with an equal mixture of ether and petroleum ether and add it to the beaker. Heat the beaker to approximately 75°C to evaporate the solvent, dry it in a drying oven at an ambient temperature of 100-105°C for 1 hour, and then weigh it. The increase from the constant weight of the beaker is taken as the fat content. If the sample does not contain any fats other than milk fat, the fat content determined above is taken as the milk fat content. If the sample contains any fats other than milk fat, the milk fat content is taken as the value obtained by subtracting the other fats from the fat content determined above.

[0013] (4) Non-fat milk solids This is measured in accordance with the method for quantifying non-fat milk solids of fermented milk and lactic acid bacteria beverages as described in the "Order Concerning Standards for Ingredients of Milk and Dairy Products." Specifically, approximately 50 g of the sample (if frozen, completely thawed at a temperature of 40°C or lower as quickly as possible) is weighed accurately, and a few drops of phenolphthalein solution are added. While stirring, 10% sodium hydroxide solution is gradually added to make it slightly alkaline, and the mixture is placed in a volumetric flask. Water is added to make a total volume of 100 mL, and 5 mL of this is accurately placed in a 150 mL Kjeldahl decomposition flask. 0.2 g of a mixed powder of 9 g of potassium sulfate and 1 g of copper sulfate is added to this, and then 10 mL of sulfuric acid is added by letting it run down the inner wall of the flask. Next, the flask is gradually heated, and when white fumes of sulfur dioxide gas are produced, the heating is increased slightly. After most of the foam has disappeared, the mixture is heated strongly, and when the liquid inside turns a clear pale blue color and no carbon deposits are observed on the inner wall of the flask, the heating is stopped. After cooling, carefully add 30 mL of water, cool again, and then connect the flask to the distillation apparatus. In this case, add 30 mL of 0.05 mol / L sulfuric acid and a few drops of methyl red solution to the 200 mL absorption flask, ensuring that the lower end of the condenser is submerged in the liquid. Next, add 40 mL of 30% sodium hydroxide solution from the funnel of the Kjeldahl distillation apparatus, rinse with 10 mL of water, close the pinch cock, and immediately begin distillation. When the distillate reaches a volume of 80 mL to 100 mL, lift the lower end of the condenser off the liquid surface and take a few more mL of the distillate. After distillation is complete, rinse the part of the condenser that was submerged in liquid with a small amount of water, combine the washings with the liquid in the absorption flask, and titrate with 0.1 mol / L sodium hydroxide solution. The non-fat milk solids (unit: mass%) are calculated by the following formula. Non-fat milk solids = {0.0014 × (A - B)} / Amount of sample taken (unit: g) × 6.38 × 2.82 × 100 A: Amount of 0.1 mol / L sodium hydroxide solution required to neutralize 30 mL of 0.05 mol / L sulfuric acid (unit: mL) B: Amount of 0.1 mol / L sodium hydroxide solution required for titration (unit: mL) Marking agent: Methyl red solution: Dissolve 1 g of methyl red in 50 mL of ethanol, add water to make 100 mL, and filter if necessary.

[0014] (5) Milk solids The sum of the milk fat content determined by the method in (3) above and the non-fat milk solids determined by the method in (4) above is defined as the milk solids. (6) Acidity Dilute 10 mL of the sample with an equal amount of carbon dioxide-free water, add 0.5 mL of phenolphthalein solution as an indicator, and titrate with 0.1 mol / L sodium hydroxide solution for 30 seconds until the point at which the faint pink color does not disappear is the limit. Determine the percentage of lactic acid per 100 g of the sample from the titration volume and define it as the acidity. 1 mL of 0.1 mol / L sodium hydroxide solution corresponds to 9 mg of lactic acid.

[0015] ≪Frozen Dessert Containing Fermented Milk≫ The frozen dessert containing fermented milk in this embodiment contains fermented milk. Typically, the frozen dessert containing fermented milk further contains frozen dessert ingredients other than fermented milk. A coating layer (also called the second layer) may be provided on the outer surface of the frozen dessert body (also called the first layer) consisting of the frozen dessert containing fermented milk to form a multi-layered frozen dessert.

[0016] <Fermented Milk> Fermented milk typically contains milk ingredients, fermentation bacteria, and water. It may also contain other ingredients.

[0017] Dairy ingredients are raw materials derived from milk, and known dairy ingredients can be used in the production of fermented milk. Examples of dairy ingredients include raw milk, cream, butter, whole milk powder, skim milk powder, concentrated milk, skimmed concentrated milk, condensed milk, cheese, whey powder, whey protein concentrate, and isolated whey protein. One type of dairy ingredient may be used, or two or more types may be used in combination.

[0018] Fermentation bacteria are bacteria used in fermentation, and in the production of fermented milk, known lactic acid bacteria, yeast, or Bifidobacterium bacteria (hereinafter also called bifidobacteria) can be used. Two or more types of fermentation bacteria can be used in combination.

[0019] The lactic acid bacteria used are not particularly limited, and any lactic acid bacteria known in the field of fermented foods can be used. Examples include bacteria of the genera Lactobacillus, Streptococcus, Lactococcus, Enterococcus, and Leuconostoc. In this invention, Bifidobacteria are not considered lactic acid bacteria.

[0020] Examples of bacteria belonging to the genus Lactobacillus include Lactobacillus delbruekii subsp. bulgaricus, Lactobacillus gasseri, Lactobacillus acidophilus, Lactobacillus helveticus, Lacticaseibacillus paracasei, and Lacticaseibacillus casei. Examples include Lactobacillus casei, Lactobacillus rhamnosus, Lactobacillus delbrüeckii, and Lactiplantibacillus plantarum. Lactobacillus delbrüeckii subspecies bulgaricus is sometimes simply abbreviated as Lactobacillus bulgaricus.

[0021] Examples of bacteria belonging to the genus Streptococcus include Streptococcus thermophilus. Examples of bacteria belonging to the genus Lactococcus include Lactococcus lactis subsp. lactis, Lactococcus lactis subsp. cremoris, and Lactococcus plantarum. Lactococcus lactis subspecies lactis is sometimes abbreviated simply as Lactococcus lactis. Similarly, Lactococcus lactis subspecies cremoris is sometimes abbreviated simply as Lactococcus cremoris.

[0022] Examples of Enterococcus bacteria include Enterococcus faecalis and Enterococcus faecium. Examples of Leuconostoc bacteria include Leuconostoc mesenteroides and Leuconostoc mesenteroides subsp. cremoris.

[0023] As for the bifidobacteria, any bifidobacteria known in fields such as fermentation can be used. For example, Bifidobacterium longum subspecies longum, Bifidobacterium longum subspecies infantis, Bifidobacterium breve, Bifidobacterium longum subspecies suis, Bifidobacterium animalis subspecies lactis. Bifidobacterium lacticis, Bifidobacterium animalis subsp. animalis, Bifidobacterium bifidum, Bifidobacterium adolescentis, Bifidobacterium angulatum, Bifidobacterium dentium, Bifidobacterium pseudocatenulatum Examples include *Bifidobacterium pseudolodium*, *Bifidobacterium pseudolodium*, and *Bifidobacterium thermophyllum*. *Bifidobacterium longum subspecies longum* is sometimes abbreviated simply as *Bifidobacterium longum*. Similarly, *Bifidobacterium longum subspecies infantis* is sometimes abbreviated simply as *Bifidobacterium infantis*.

[0024] Fermented milk preferably contains Bifidobacterium because various physiological effects are expected from its metabolites. Bifidobacterium may be used in combination with other fermenting bacteria, such as lactic acid bacteria.

[0025] As other components, components known in the production of fermented milk can be used. Examples of other components include sweeteners and vegetable fats.

[0026] Examples of sweeteners include saccharides such as sugar (e.g., refined sugar, granulated sugar, brown sugar, and black sugar), starch syrup, starch syrup, sugar-mixed isomerized sugar, isomerized sugar, lactose, glucose, maltose, fructose, invert sugar, reduced malt starch syrup, honey, trehalose, palatinose, and D-xylose; sugar alcohols such as xylitol, sorbitol, maltitol, and erythritol; high-intensity sweeteners such as sodium saccharin, cyclamate and its salts, acesulfame potassium, thaumatin, aspartame, sucralose, alitame, neotame, and stevioside contained in stevia extract; etc. The sweetener may be used alone or in combination of two or more.

[0027] The solid content of the fermented milk is, for example, 20% by mass or more, further 21% by mass or more, further 22% by mass or more, further 23% by mass or more, further 24% by mass or more with respect to the total mass of the fermented milk, and also, for example, 31% by mass or less, further 30% by mass or less, further 29% by mass or less, further 28% by mass or less, further 27% by mass or less. The upper limit value and the lower limit value of the solid content of the fermented milk can be arbitrarily combined. For example, the solid content of the fermented milk may be, for example, 20% by mass or more and 31% by mass or less, 21% by mass or more and 30% by mass or less, 22% by mass or more and 29% by mass or less, 23% by mass or more and 28% by mass or less, or 24% by mass or more and 27% by mass or less with respect to the total mass of the fermented milk.

[0028] The fat content of the fermented milk is, for example, 3% by mass or more, further 4% by mass or more, and further 5% by mass or more with respect to the total mass of the fermented milk, and is, for example, 9% by mass or less, further 8% by mass or less, and further 7% by mass or less. The upper limit and the lower limit of the fat content of the fermented milk can be arbitrarily combined. For example, the fat content of the fermented milk may be 3% by mass or more and 9% by mass or less, 4% by mass or more and 8% by mass or less, or 5% by mass or more and 7% by mass or less with respect to the total mass of the fermented milk. The fat content of the fermented milk may be milk fat or a mixture of milk fat and vegetable fat. Milk fat is preferable in terms of excellent milk flavor.

[0029] The milk fat content of the fermented milk is, for example, 3% by mass or more, further 4% by mass or more, and further 5% by mass or more with respect to the total mass of the fermented milk, and is, for example, 9% by mass or less, further 8% by mass or less, and further 7% by mass or less. The upper limit and the lower limit of the milk fat content of the fermented milk can be arbitrarily combined. For example, the milk fat content of the fermented milk may be 3% by mass or more and 9% by mass or less, 4% by mass or more and 8% by mass or less, or 5% by mass or more and 7% by mass or less with respect to the total mass of the fermented milk.

[0030] The non-fat milk solids content of the fermented milk is, for example, 8% by mass or more, further 9% by mass or more, further 10% by mass or more, further 11% by mass or more, and further 12% by mass or more with respect to the total mass of the fermented milk, and is, for example, 20% by mass or less, further 19% by mass or less, further 18% by mass or less, further 17% by mass or less, and further 16% by mass or less. The upper limit and the lower limit of the non-fat milk solids content of the fermented milk can be arbitrarily combined. For example, the non-fat milk solids content of the fermented milk may be 8% by mass or more and 20% by mass or less, 9% by mass or more and 19% by mass or less, 10% by mass or more and 18% by mass or less, 11% by mass or more and 17% by mass or less, or 12% by mass or more and 16% by mass or less with respect to the total mass of the fermented milk.

[0031] The acidity of the fermented milk is, for example, 0.75% by mass or more, more specifically 0.80% by mass or more, more specifically 0.85% by mass or more, and also, for example, 1.35% by mass or less, more specifically 1.30% by mass or less, and more specifically 1.25% by mass or less, relative to the total mass of the fermented milk. The upper and lower limits of the acidity of the fermented milk can be arbitrarily combined. For example, the acidity of the fermented milk may be 0.75% by mass or more and 1.35% by mass or less, 0.80% by mass or more and 1.30% by mass or less, or 0.85% by mass or more and 1.25% by mass or less, relative to the total mass of the fermented milk.

[0032] <Ingredients for frozen desserts other than fermented milk> Ingredients for frozen desserts other than fermented milk (hereinafter also simply referred to as "ingredients for frozen desserts") typically include sweeteners and water. Ingredients for frozen desserts preferably include milk ingredients. Ingredients for frozen desserts may further include other ingredients.

[0033] Sweeteners and dairy ingredients are the same as those described above. Other ingredients include egg components, vegetable oils and fats, dietary fiber, emulsifiers, stabilizers, acidulants, flavorings, colorings, taste enhancers, and other food additives. Stabilizers include polysaccharides such as locust bean gum, guar gum, carrageenan, pectin, and xanthan gum, as well as cellulose, agar, gelatin, and modified starch. Emulsifiers include glycerin fatty acid esters, propylene glycol fatty acid esters, sucrose fatty acid esters, sorbitan fatty acid esters, polyglycerin fatty acid esters, organic acid monoglycerides, and organic acid diglycerides. Organic acids in organic acid monoglycerides and organic acid diglycerides include citric acid and lactic acid. Taste enhancers are ingredients that can be uniformly dissolved or dispersed in the raw material liquid obtained by mixing fermented milk and frozen dessert ingredients, such as salt, fruit juice, matcha, coffee, black tea, and alcohol. The frozen dessert ingredients may include at least one of the following: fruits, nuts, etc., and solid materials that are unevenly dispersed in the liquid ingredients, to the extent that it does not interfere with the manufacture of the frozen dessert. These ingredients may be used individually or in combination of two or more.

[0034] The frozen dessert ingredient preferably contains propylene glycol fatty acid ester. When the frozen dessert ingredient contains propylene glycol fatty acid ester, the growth of ice crystals during the freezing process is suppressed, resulting in smaller ice crystals in the partially frozen product and, consequently, smaller ice crystals in the fermented milk-containing frozen dessert. This results in a smoother texture and improved spoonability when the fermented milk-containing frozen dessert is eaten. While propylene glycol fatty acid ester has been known to suppress ice crystal growth due to temperature changes during frozen storage, its ability to reduce ice crystal size during the freezing process was previously unknown. Since the processes of ice crystal growth during temperature changes in frozen dessert storage and ice crystal formation during the freezing process are different, this discovery was unexpected. Propylene glycol fatty acid ester may also be used in combination with other emulsifiers.

[0035] <Characteristics of frozen desserts containing fermented milk> The overrun of frozen desserts containing fermented milk is 80% or less, preferably 70% or less, more preferably 65% ​​or less, more preferably 60% or less, more preferably 57% or less, more preferably 55% or less, more preferably 53% or less, and more preferably 50% or less, and also preferably 15% or more, more preferably 20% or more, and more preferably 25% or more. The above lower and upper limits can be combined as appropriate. For example, the overrun of frozen desserts containing fermented milk may be 15% or more and 80% or less, 20% or more and 70% or less, 25% or more and 65% or less, 25% or more and 60% or less, 25% or more and 57% or less, 25% or more and 55% or less, 25% or more and 53% or less, or 25% or more and 50% or less. When the overrun is below the above upper limit, the smoothness and density of the texture are excellent. When the overrun is above the above lower limit, the ease of scooping and melt-in-the-mouth quality when eaten are even better.

[0036] The median diameter of ice crystals in fermented milk-containing frozen desserts is 60 μm or less, preferably 59 μm or less, more preferably 58 μm or less, more preferably 57 μm or less, more preferably 56 μm or less, more preferably 55 μm or less, more preferably 54 μm or less, more preferably 53 μm or less, more preferably 52 μm or less, more preferably 51 μm or less, more preferably 50 μm or less, more preferably 49 μm or less, more preferably 48 μm or less, more preferably 47 μm or less, more preferably 46 μm or less, more preferably 45 μm or less, more preferably 44 μm or less, more preferably 43 μm or less, more preferably 42 μm or less, more preferably 41 μm or less, and more preferably 40 μm or less. The above lower and upper limits can be combined as appropriate. For example, the median diameter of ice crystals in a frozen dessert containing fermented milk may be 20 μm or more and 60 μm or less, preferably 24 μm or more and 59 μm or less, more preferably 24 μm or more and 58 μm or less, even more preferably 24 μm or more and 57 μm or less, even more preferably 24 μm or more and 56 μm or less, even more preferably 24 μm or more and 55 μm or less, even more preferably 24 μm or more and 54 μm or less, even more preferably 24 μm or more and 53 μm or less, even more preferably 24 μm or more and 52 μm or less, and even more preferably 24 μm or more and 5 The particle size may be 1 μm or less, 24 μm to 50 μm, 24 μm to 49 μm, 24 μm to 48 μm, 24 μm to 47 μm, 24 μm to 46 μm, 24 μm to 45 μm, 24 μm to 44 μm, 24 μm to 43 μm, 24 μm to 42 μm, 24 μm to 41 μm, or 24 μm to 40 μm. If the median value is below the above upper limit, the texture will be smoother. If the median value is above the above lower limit, the cooling sensation when eaten will be even better.

[0037] The average diameter of ice crystals in fermented milk-containing frozen desserts is 60 μm or less, preferably 59 μm or less, more preferably 58 μm or less, more preferably 57 μm or less, more preferably 55 μm or less, more preferably 50 μm or less, more preferably 49 μm or less, more preferably 48 μm or less, more preferably 47 μm or less, more preferably 46 μm or less, and more preferably 45 μm or less, and also 20 μm or more, preferably 24 μm or more. The above lower and upper limits can be combined as appropriate. For example, the average diameter of ice crystals in a frozen dessert containing fermented milk may be 20 μm or more and 60 μm or less, preferably 24 μm or more and 59 μm or less, more preferably 24 μm or more and 58 μm or less, even more preferably 24 μm or more and 57 μm or less, even more preferably 24 μm or more and 55 μm or less, even more preferably 24 μm or more and 50 μm or less, even more preferably 24 μm or more and 49 μm or less, even more preferably 24 μm or more and 48 μm or less, even more preferably 24 μm or more and 47 μm or less, even more preferably 24 μm or more and 46 μm or less, and even more preferably 24 μm or more and 45 μm or less. If the average value is below the above upper limit, the smoothness of the texture is excellent. If the median value is above the above lower limit, the cooling sensation when eaten is even better.

[0038] The standard deviation of the diameter of ice crystals in fermented milk-containing frozen desserts is preferably 24 μm or less, more preferably 23 μm or less, more preferably 22 μm or less, more preferably 21 μm or less, and more preferably 20 μm or less. A smaller standard deviation is preferable, and the lower limit is not particularly limited, but for example, it is 12 μm or more. When the standard deviation is below the above upper limit, the smoothness of the texture is better. The upper and lower limits of the standard deviation of the diameter of ice crystals in fermented milk-containing frozen desserts can be arbitrarily combined. For example, the standard deviation of the diameter of ice crystals in fermented milk-containing frozen desserts may be 12 μm or more and 24 μm or less, 12 μm or more and 23 μm or less, 12 μm or more and 22 μm or less, 12 μm or more and 21 μm or less, or 12 μm or more and 20 μm or less.

[0039] In frozen desserts containing fermented milk, the fermented milk content is preferably 60% by mass or more, more preferably 65% ​​by mass or more, and more preferably 80% by mass or less, and more preferably 75% by mass or less, based on the total mass of the frozen dessert. The above lower and upper limits can be combined as appropriate. When the fermented milk content is above the lower limit, a refreshing flavor from the fermented milk is easily obtained. The upper and lower limits for the fermented milk content in frozen desserts containing fermented milk can be combined arbitrarily. For example, in frozen desserts containing fermented milk, the fermented milk content is preferably 60% by mass or more and 80% by mass or less, and more preferably 65% ​​by mass or more and 75% by mass or less, based on the total mass of the frozen dessert. When the fermented milk content is below the upper limit, the smoothness of the texture is superior. The total mass of frozen desserts containing fermented milk is the sum of the fermented milk and the frozen dessert ingredients other than fermented milk.

[0040] The Bifidobacterium content is 10 per 1 mL of fermented milk-containing frozen dessert. ６ Preferably, the amount is 10 or more (in Colony Forming Unit (CFU)). ７ The above is preferable. The upper limit is not particularly limited, but for example, 10 １０ The following applies. The upper and lower limits for the Bifidobacterium content can be combined arbitrarily. For example, the Bifidobacterium content is 10 per 1 mL of fermented milk-containing frozen dessert. ６ CFU or higher 10 １０ CFU or less or 10 ７ CFU or higher 10 １０ It may be below CFU.

[0041] The content of propylene glycol fatty acid ester is preferably 0.05% by mass or more, more preferably 0.07% by mass or more, and even more preferably 0.09% by mass or more, based on the total mass of the fermented milk-containing frozen dessert. There is no particular upper limit, but for example, it is 0.3% by mass or less. The above lower limit and upper limit can be combined as appropriate. For example, the content of propylene glycol fatty acid ester is preferably 0.05% by mass or more and 0.3% by mass or less, based on the total mass of the fermented milk-containing frozen dessert, and more preferably 0.07% by mass or more and 0.3% by mass or less. When the content of propylene glycol fatty acid ester is above the above lower limit, the consistency is better.

[0042] The solid content of a frozen dessert containing fermented milk may be, for example, 26% by mass or more, more precisely 27% by mass or more, more precisely 28% by mass or more, more precisely 29% by mass or more, or more precisely 30% by mass or more, relative to the total mass of the frozen dessert containing fermented milk. Alternatively, it may be, for example, 40% by mass or less, more precisely 39% by mass or less, more precisely 38% by mass or less, more precisely 37% by mass or less, more precisely 36% by mass or less, or more precisely 34% by mass or less. The upper and lower limits of the solid content of a frozen dessert containing fermented milk can be arbitrarily combined. For example, the solid content of a frozen dessert containing fermented milk may be, for example, 26% by mass or more and 40% by mass or less, 27% by mass or more and 39% by mass or less, 28% by mass or more and 38% by mass or less, 29% by mass or more and 37% by mass or less, 30% by mass or more and 36% by mass or less, or 26% by mass or more and 34% by mass or less, relative to the total mass of the frozen dessert containing fermented milk.

[0043] The fat content of frozen desserts containing fermented milk is, for example, 5.0% by mass or more, more specifically 5.1% by mass or more, more specifically 5.2% by mass or more, more specifically 5.3% by mass or more, more specifically 5.4% by mass or more, more specifically 5.5% by mass or more, more specifically 5.6% by mass or more, more specifically 5.7% by mass or more, more specifically 5.8% by mass or more, more specifically 5.9% by mass or more, and more specifically 6.0% by mass or more, and also, for example, 9.0% by mass or less, more specifically 8.9% by mass or less, more specifically 8.8% by mass or less, more specifically 8.7% by mass or less, more specifically 8.6% by mass or less, more specifically 8.5% by mass or less, more specifically 8.4% by mass or less, more specifically 8.3% by mass or less, more specifically 8.2% by mass or less, more specifically 8.1% by mass or less, and more specifically 8.0% by mass or less, relative to the total mass of the frozen dessert containing fermented milk. For example, the fat content of a frozen dessert containing fermented milk may be, for example, 5.0% to 9.0% by mass, 5.1% to 8.9% by mass, 5.2% to 8.8% by mass, 5.3% to 8.7% by mass, 5.4% to 8.6% by mass, 5.5% to 8.5% by mass, 5.6% to 8.4% by mass, 5.7% to 8.3% by mass, 5.8% to 8.2% by mass, 5.9% to 8.1% by mass, or 6.0% to 8.0% by mass, relative to the total mass of the frozen dessert containing fermented milk.

[0044] The milk fat content of frozen desserts containing fermented milk should be, for example, 1.8% by mass or more, more specifically 1.9% by mass or more, more specifically 2.0% by mass or more, more specifically 2.1% by mass or more, more specifically 2.2% by mass or more, more specifically 2.3% by mass or more, more specifically 2.4% by mass or more, more specifically 2.5% by mass or more, more specifically 2.6% by mass or more, more specifically 2.7% by mass or more, more specifically 2.8% by mass or more, and more specifically 2.9% by mass, relative to the total mass of the frozen desserts containing fermented milk. It is % or more, more specifically 3.0% by mass or more, more specifically 3.3% by mass or more, and also, for example, 9.0% by mass or less, more specifically 8.9% by mass or less, more specifically 8.8% by mass or less, more specifically 8.7% by mass or less, more specifically 8.6% by mass or less, more specifically 8.5% by mass or less, more specifically 8.4% by mass or less, more specifically 8.3% by mass or less, more specifically 8.2% by mass or less, more specifically 8.1% by mass or less, and more specifically 8.0% by mass or less. The upper and lower limits for the milk fat content of fermented milk-containing frozen desserts can be arbitrarily combined. For example, the milk fat content of a frozen dessert containing fermented milk may be 1.8% to 9.0% by mass, 1.9% to 8.9% by mass, 2.0% to 8.8% by mass, 2.1% to 8.7% by mass, 2.2% to 8.6% by mass, 2.3% to 8.5% by mass, 2.4% to 8.4% by mass, 2.5% to 8.3% by mass, 2.6% to 8.2% by mass, 2.7% to 8.1% by mass, 2.8% to 8.0% by mass, 2.9% to 8.0% by mass, 3.0% to 8.0% by mass, or 3.3% to 9.0% by mass, relative to the total mass of the frozen dessert containing fermented milk.

[0045] The non-fat milk solids content of fermented milk-containing frozen desserts is, for example, 8.0% by mass or more, more specifically 8.1% by mass or more, more specifically 8.2% by mass or more, more specifically 8.3% by mass or more, more specifically 8.4% by mass or more, more specifically 8.5% by mass or more, more specifically 8.6% by mass or more, more specifically 8.7% by mass or more, more specifically 8.8% by mass or more, more specifically 8.9% by mass or more, and more specifically 9.0% by mass or more, and also, for example, 12.0% by mass or less, more specifically 11.9% by mass or less, more specifically 11.8% by mass or less, more specifically 11.7% by mass or less, more specifically 11.6% by mass or less, more specifically 11.5% by mass or less, more specifically 11.4% by mass or less, more specifically 11.3% by mass or less, more specifically 11.2% by mass or less, more specifically 11.1% by mass or less, and more specifically 11.0% by mass or less, relative to the total mass of the fermented milk-containing frozen dessert. The upper and lower limits for the non-fat milk solids content of fermented milk-containing frozen desserts can be any combination. For example, the non-fat milk solids content of a fermented milk-containing frozen dessert may be 8.0% to 12.0%, 8.1% to 11.9%, 8.2% to 11.8%, 8.3% to 11.7%, 8.4% to 11.6%, 8.5% to 11.5%, 8.6% to 11.4%, 8.7% to 11.3%, 8.8% to 11.2%, 8.9% to 11.1%, or 9.0% to 11.0% relative to the total mass of the fermented milk-containing frozen dessert.

[0046] The ratio of non-fat milk solids derived from fermented milk to the total non-fat milk solids in frozen desserts containing fermented milk is, for example, 60% by mass or more, more precisely 61% by mass or more, more precisely 62% by mass or more, more precisely 63% by mass or more, more precisely 64% by mass or more, more precisely 65% ​​by mass or more, and more precisely 66% by mass or more. Alternatively, it may be, for example, 90% by mass or less, more precisely 89% by mass or less, more precisely 88% by mass or less, more precisely 87% by mass or less, more precisely 86% by mass or less, more precisely 85% by mass or less, and more precisely 84% by mass or less. The upper and lower limits for the ratio of non-fat milk solids derived from fermented milk can be arbitrarily combined. For example, the ratio of non-fat milk solids derived from fermented milk to the total non-fat milk solids in a frozen dessert containing fermented milk may be 60% by mass or more and 90% by mass or less, 61% by mass or more and 89% by mass or less, 62% by mass or more and 88% by mass or less, 63% by mass or more and 87% by mass or less, 64% by mass or more and 86% by mass or less, 65% by mass or more and 85% by mass or less, or 66% by mass or more and 84% by mass or less.

[0047] The acidity of frozen desserts containing fermented milk is, for example, 0.50% by mass or more, more preferably 0.51% by mass or more, more preferably 0.52% by mass or more, more preferably 0.53% by mass or more, more preferably 0.54% by mass or more, more preferably 0.55% by mass or more, more preferably 0.56% by mass or more, more preferably 0.57% by mass or more, more preferably 0.58% by mass or more, more preferably 0.59% by mass or more, and more preferably 0.60% by mass or more, relative to the total mass of the frozen desserts containing fermented milk. The limits are 0% by mass or less, 1.09% by mass or less, 1.08% by mass or less, 1.07% by mass or less, 1.06% by mass or less, 1.05% by mass or less, 1.04% by mass or less, 1.03% by mass or less, 1.02% by mass or less, 1.01% by mass or less, 1.00% by mass or less, 0.99% by mass or less, 0.98% by mass or less, and 0.97% by mass or less. The upper and lower limits of acidity for fermented milk-containing frozen desserts can be arbitrarily combined. For example, the acidity of a frozen dessert containing fermented milk may be 0.50% to 1.10% by mass, 0.51% to 1.09% by mass, 0.52% to 1.08% by mass, 0.53% to 1.07% by mass, 0.54% to 1.06% by mass, 0.55% to 1.05% by mass, 0.56% to 1.04% by mass, 0.57% to 1.03% by mass, 0.58% to 1.02% by mass, 0.59% to 1.01% by mass, or 0.60% to 0.97% by mass, relative to the total mass of the frozen dessert containing fermented milk.

[0048] The specific gravity of frozen desserts containing fermented milk is, for example, 1.0820 or higher, more preferably 1.0830 or higher, more preferably 1.0840 or higher, more preferably 1.0850 or higher, more preferably 1.0860 or higher, and also, for example, 1.1000 or lower, more preferably 1.0990 or lower, more preferably 1.0980 or lower, more preferably 1.0970 or lower, and more preferably 1.0960 or lower. The upper and lower limits of the specific gravity of frozen desserts containing fermented milk can be combined arbitrarily. For example, the specific gravity of frozen desserts containing fermented milk may be 1.0820 or higher and 1.1000 or lower, 1.0830 or higher and 1.0990 or lower, 1.0840 or higher and 1.0980 or lower, 1.0850 or higher and 1.0970 or lower, or 1.0860 or higher and 1.0960 or lower.

[0049] The freezing point of frozen desserts containing fermented milk is, for example, -3.5°C or higher, more preferably -3.4°C or higher, more preferably -3.3°C or higher, more preferably -3.2°C or higher, more preferably -3.1°C or higher, and more preferably -3.0°C or higher, and also, for example, -2.2°C or lower, more preferably -2.3°C or lower, more preferably -2.4°C or lower, more preferably -2.5°C or lower, and more preferably -2.6°C or lower. The upper and lower limits of the freezing point of frozen desserts containing fermented milk can be any combination. For example, it may be -3.5°C or higher and -2.2°C or lower, -3.4°C or higher and -2.3°C or lower, -3.3°C or higher and -2.4°C or lower, -3.2°C or higher and -2.5°C or lower, -3.1°C or higher and -2.5°C or lower, or -3.0°C or higher and -2.6°C or lower.

[0050] <Effects> The fermented milk-containing frozen dessert of this embodiment has an overrun of 80% or less and a median ice crystal diameter of 60 μm or less, resulting in a smooth texture.

[0051] The smoothness of the texture of frozen desserts, such as those containing fermented milk, can be evaluated by the peak count obtained from texture measurement using a texture analyzer. A lower peak count tends to indicate a smoother texture. A texture analyzer is a device that measures the stress (strength of rebound) at which a probe penetrates the sample at a constant speed. It is used to evaluate properties such as hardness under compression and adhesion under tension from the changes in stress. For example, the TA.XT plusC from Stable Micro Systems can be used as a texture analyzer.

[0052] For peak count measurement, a cylindrical probe with a diameter of 4 mm is used. The sample is pre-temperature-controlled in a -15°C chamber for at least 15 hours, and immediately after removal from the chamber, it is subjected to texture measurement in a 25°C atmosphere. The method for measuring peak count will be explained in detail using a frozen dessert in a cup container as an example. The sample, which has been temperature-controlled to -15°C, is placed on the measuring platform of the texture analyzer, and the probe (cylindrical, stainless steel, with a diameter of 4 mm) connected to the texture analyzer is lowered from above the center of the sample at a speed of 1 mm / second, penetrating to a depth of 20 mm from the surface of the sample. The stress (g) during this time is measured. In a graph with the elapsed time (seconds) from the moment the probe tip contacts the sample surface on the horizontal axis and stress (g) on ​​the vertical axis, the moment when the stress (g) instantaneously turns negative and then turns positive again is defined as a "peak," and the number of peaks in which the negative stress (g) exceeds a threshold is defined as the peak count. The threshold can be set, for example, in the range of 3 to 5 g.

[0053] Figures 1 and 2 schematically show graphs obtained when texture measurements are performed on typical frozen yogurt and ice cream, respectively. In the case of typical ice cream, the resulting curve is smooth with little waveform distortion, as shown in Figure 2. On the other hand, in the case of typical frozen yogurt, the resulting curve shows many large waveform distortions, as shown in Figure 1. According to the inventors' research, there is a tendency for the number of peak counts to decrease as the median diameter of the ice crystals decreases.

[0054] In this embodiment, the fermented milk frozen dessert preferably has a peak count of 20 or less, more preferably 15 or less, and even more preferably 10 or less, when the threshold is set to 3 g in the above measurement method.

[0055] ≪Method for producing frozen dessert containing fermented milk≫ The method for producing frozen dessert containing fermented milk according to this embodiment includes the steps of: mixing fermented milk with frozen dessert ingredients other than the fermented milk to obtain a raw material liquid (raw material liquid preparation step); freezing the raw material liquid to obtain a partially frozen product (freezing step); shaping the partially frozen product (shaping step); and hardening the shaped partially frozen product (hardening step). A step of preparing fermented milk (fermented milk preparation step) may be included before the step of obtaining the raw material liquid.

[0056] <Fermented Milk Preparation Process> The method for preparing fermented milk is not particularly limited. Known methods can be used. For example, fermented milk can be obtained by fermenting a milk preparation liquid containing milk raw materials and water. The milk preparation liquid may contain the other components mentioned above. In preparing the milk preparation liquid, the raw materials are mixed, preferably homogenized, and then heat-sterilized. Homogenization and heat sterilization can be carried out by conventional methods.

[0057] Fermentation is performed by adding (inoculating) fermentation bacteria to the formula milk solution, maintaining the temperature according to the fermentation bacteria, and then cooling the solution to obtain a fermented product. As fermentation progresses, the acidity of the formula milk solution increases (i.e., the pH decreases), so once the desired acidity is reached, the solution is cooled to stop the fermentation. It is preferable to use a bifidobacteria starter as the fermentation bacteria. A bifidobacteria starter may be used in combination with other fermentation bacteria starters, such as a lactic acid bacteria starter. These starters are available commercially.

[0058] After fermentation is complete, the resulting fermented product may be heat-treated. The heat-treatment temperature is, for example, 53 to 65°C, and more specifically, 56 to 60°C. The heat-treatment time, during which the product is maintained at the heat-treatment temperature, is, for example, 60 to 180 seconds.

[0059] The resulting fermented product may be concentrated. Methods for concentrating the fermented product include, for example, known methods such as centrifugation and membrane separation. Examples of membrane separation methods include using an ultrafiltration membrane (UF membrane) or a microfiltration membrane (MF membrane).

[0060] <Preparation Process for Raw Material Liquid> The method of mixing fermented milk with other frozen dessert ingredients is not particularly limited. It is preferable to mix all frozen dessert ingredients beforehand before mixing with fermented milk. Hereinafter, the mixture of all frozen dessert ingredients other than fermented milk will also be referred to as the frozen dessert ingredient mix.

[0061] The solid content of the frozen dessert mix is, for example, 35% by mass or more, more specifically 36% by mass or more, more specifically 37% by mass or more, more specifically 38% by mass or more, more specifically 39% by mass or more, and also, for example, 48% by mass or less, more specifically 47% by mass or less, more specifically 46% by mass or less, more specifically 45% by mass or less, and more specifically 44% by mass or less. The upper and lower limits for the solid content of the frozen dessert mix can be any combination. For example, the solid content of the frozen dessert mix may be 35% by mass or more and 48% by mass or less, 36% by mass or more and 47% by mass or less, 37% by mass or more and 46% by mass or less, 38% by mass or more and 45% by mass or less, or 39% by mass or more and 44% by mass or less, relative to the total mass of the frozen dessert mix.

[0062] The fat content of the frozen dessert mix is, for example, 6% by mass or more, more precisely 7% by mass or more, more precisely 8% by mass or more, and also, for example, 15% by mass or less, more precisely 14% by mass or less, more precisely 13% by mass or less, more precisely 12% by mass or less, more precisely 11% by mass or less, and more precisely 10% by mass or less, relative to the total mass of the frozen dessert mix. The upper and lower limits of the fat content of the frozen dessert mix can be any combination. For example, the fat content of the frozen dessert mix may be 6% by mass or more and 15% by mass or less, 7% by mass or more and 13% by mass or less, or 8% by mass or more and 10% by mass or less, relative to the total mass of the frozen dessert mix.

[0063] The milk fat content of the frozen dessert mix is, for example, 3% by mass or more, more precisely 4% by mass or more, more precisely 5% by mass or more, and also, for example, 12% by mass or less, more precisely 11% by mass or less, and more precisely 10% by mass or less, relative to the total mass of the frozen dessert mix. The upper and lower limits of the milk fat content of the frozen dessert mix can be arbitrarily combined. For example, the milk fat content of the frozen dessert mix may be 3% by mass or more and 12% by mass or less, 4% by mass or more and 11% by mass or less, or 5% by mass or more and 10% by mass or less, relative to the total mass of the frozen dessert mix.

[0064] The non-fat milk solids content of the frozen dessert mix is, for example, 4% by mass or more, more precisely 4.5% by mass or more, more precisely 5% by mass or more, and also, for example, 11% by mass or less, more precisely 10% by mass or less, more precisely 9% by mass or less, more precisely 8% by mass or less, and more precisely 7% by mass or less, based on the total mass of the frozen dessert mix. The upper and lower limits of the non-fat milk solids content of the frozen dessert mix can be any combination. For example, the non-fat milk solids content of the frozen dessert mix may be 4% by mass or more and 11% by mass or less, 4.5% by mass or more and 10% by mass or less, or 5% by mass or more and 7% by mass or less, based on the total mass of the frozen dessert mix.

[0065] The preferred range for the content of fermented milk relative to the total mass of the raw material liquid is the same as the preferred range for the content of fermented milk relative to the total mass of frozen desserts containing fermented milk. The same applies to the preferred ranges for the content of solids, fat, milk fat, and milk fat solids of the raw material liquid relative to the total mass of the raw material liquid, as well as the preferred ranges for the acidity, specific gravity, and freezing point of the raw material liquid.

[0066] <Freezing Process> In the freezing process, while flowing the raw material liquid, it is frozen at a temperature lower than the freezing point to obtain a partially frozen product with fluidity. At this time, it may be frozen while containing air. The freezing can be carried out by a known method. For example, it can be carried out using a known continuous freezer or a known batch freezer. A general continuous freezer includes a substantially cylindrical cylinder and a dasher having a rotating shaft coaxial with the cylinder. The cylinder freezes the moisture in the raw material liquid flowing inside from one end to the other end. The dasher rotates while scraping off the deposits on the inner wall of the cylinder and stirs the inside of the cylinder. Hereinafter, the freezing process using a continuous freezer will be taken as an example for explanation, but a batch freezer can also be used in the same manner.

[0067] First, the raw material liquid is supplied to the continuous freezer. The raw material liquid supplied to the continuous freezer is mixed with air and introduced into the cylinder, frozen while containing air bubbles inside the cylinder to become a partially frozen product, and then discharged.

[0068] The temperature of the partially frozen product discharged from the continuous freezer (also referred to as the freezing temperature) is T when the freezing point (°C) of the raw material liquid is T. １ Then, usually, it is less than T. １ It may be -0.1 °C or less, -0.2 °C or less, or -0.3 °C or less, and also, it may be -1.0 °C or more, -0.8 °C or more, or -0.6 °C or more. The upper and lower limit values of the freezing temperature can be arbitrarily combined. For example, the freezing temperature is -1.0 °C or more and less than T, -0.8 °C or more and -0.1 °C or less, -0.6 °C or more and -0.2 °C or less, or -0.6 °C or more and -0.6 °C or more. １ -0.1 °C or less, T １ -0.2 °C or less, or T １ -0.3 °C or less, and also, T １ -1.0 °C or more, T １ -0.8 °C or more, or T １ -0.6 °C or more. The upper and lower limit values of the freezing temperature can be arbitrarily combined. For example, the freezing temperature is １ -1.0 °C or more and less than T １ It is less than T, １ -0.8 °C or more and １ -0.1 °C or less, T １ -0.6 °C or more and １ -0.2 °C or less, or T １ -0.6 °C or more and １The temperature may be -0.3°C or lower. If the freezing temperature is below the above upper limit, it is easier to improve the shape retention of partially frozen products. If the freezing temperature is above the above lower limit, air pockets are less likely to form during filling, making it easier to mold.

[0069] The overrun of the partially frozen product obtained in the freezing process is 80% or less, preferably 70% or less, more preferably 65% ​​or less, more preferably 60% or less, more preferably 57% or less, more preferably 55% or less, more preferably 53% or less, and more preferably 50% or less, and also preferably 15% or more, more preferably 20% or more, and more preferably 25% or more. The upper and lower limits of the overrun of the partially frozen product can be any combination. For example, the overrun of the partially frozen product may be 15% or more and 80% or less, preferably 20% or more and 70% or less, more preferably 25% or more and 65%, and may also be 25% or more and 60%, 25% or more and 57%, 25% or more and 55%, 25% or more and 53%, or 25% or more and 50% or less. When the overrun is below the above upper limits, the smoothness and density of the texture of the fermented milk-containing frozen dessert are excellent. When the overrun is above the lower limit mentioned above, the spoon glides through the mouth and melts better when eaten. The overrun can be adjusted by the amount of air mixed into the raw material liquid during the freezer (freezing process).

[0070] <Molding Process> The molding process can be carried out using known methods. For example, a method of filling a cup or mold with partially frozen material, or a method of extruding the partially frozen material can be used.

[0071] The temperature of the partially frozen material during molding (also called the molding temperature) is calculated by setting the freezing point (°C) of the partially frozen material to T. ２ Therefore, T ２ -1°C or higher, T ２ -0.9°C or higher is preferred, T ２ -0.8℃ or higher is more preferable, T ２ -0.7°C or higher is more preferable, and T ２ It is below ℃, T ２ -0.1℃ or lower is preferred, T ２ -0.2℃ or lower is more preferable, T ２A temperature of -0.3°C or lower is even more preferable. The upper and lower limits of the molding temperature can be arbitrarily combined. For example, the molding temperature is T ２ -1℃ or more T ２ It may be less than ℃, T ２ -0.9℃ or moreT ２ -0.1℃ or lower is preferred, T ２ -0.8℃ or higher, T ２ -0.2℃ or lower is more preferable, T ２ -0.7℃ or moreT ２ A temperature of -0.3°C or lower is even more preferable. If the molding temperature is above the lower limit, air pockets are less likely to form, making molding easier. If the molding temperature is below the upper limit, a smooth texture is more easily obtained. When molding partially frozen material discharged from a continuous freezer, the freezing temperature can be considered the molding temperature.

[0072] <Curing Process> In the curing process, the molded partially frozen product is frozen and cured, for example, in a freezer with an ambient temperature of -30°C or lower. Ingredients may be added to the partially frozen product, molded and cured, to produce a composite frozen dessert consisting of the cured partially frozen product (frozen dessert) and ingredients. The cured partially frozen product (i.e., fermented milk-containing frozen dessert) preferably consists of a homogeneous continuous phase formed from a uniform oil-in-water emulsion that has cured.

[0073] The present invention will be described in more detail below using examples. However, the present invention is not limited to these examples. In the following, the unit of content, "%", refers to "mass%" unless otherwise specified.

[0074] <Evaluation Method> [Ice Crystal Size] A portion of the frozen dessert containing fermented milk was taken and observed with an optical microscope, and the diameter of the ice crystals was determined from the equivalent circular diameter in the observed image. The measuring equipment used was an optical microscope (Nikon Co. Ltd., product name Nikon Eclipse E400) and a slide (Matsunami Glass Ind., Ltd., product name S1225). The inside of a temperature-controlled freezer glove box was set to -15°C, and the optical microscope and the experimental equipment to be used were placed inside. After the inside of the box had cooled sufficiently, the frozen dessert containing fermented milk in a cup container was transferred into the box and stored for about 12 hours to regulate the temperature. A small sample was taken from the center of the frozen dessert containing fermented milk in a cup container using a spatula. The sample was placed in the center of the slide, and a few drops of isobutanol were added on top to remove the fat. Another slide was placed on top, pushing out any air bubbles. The slide was held at a distance from the sample and slowly moved back and forth and side to side to disperse the ice crystals in the sample so that they did not overlap. With the slide in this state, it was placed on an observation stage and the ice crystals in the sample were observed at a magnification of 350x. The area of ​​the ice crystals observed two-dimensionally from above was measured using image analysis software (Media Cybernetics product name Image Pro Plus ver7.0) for the obtained field of view image. The diameter (R, equivalent diameter of a circle) when the measured area (A) is assumed to be a circle was calculated using the following formula: R = 2 × √(A / π). The number and diameter (R, unit: μm) of all ice crystals confirmed within the field of view were measured, and the mean, median, standard deviation, maximum, and minimum values ​​were determined.

[0075] [Peak Count] The temperature inside a temperature-controlled freezer was set to -15°C. After the freezer had cooled sufficiently, fermented milk-containing frozen desserts in cup containers were transferred into the freezer and stored for approximately 15 hours to regulate the temperature. The temperature-controlled fermented milk-containing frozen desserts in cup containers were placed on the measuring platform of a texture analyzer (Stable Micro Systems product name TA.XT plus C). A probe (cylindrical, stainless steel, 4 mm in diameter) connected to the texture analyzer was lowered from above the center of the fermented milk-containing frozen dessert at a speed of 1 mm / second, penetrating to a depth of 20 mm from the surface of the frozen dessert. The stress (g) during this time was measured, and the peak count was determined using the analysis software (Exponent Connect) included with the texture analyzer. In a graph plotted with the elapsed time (seconds) from the moment the probe tip contacted the surface of the fermented milk-containing frozen dessert on the horizontal axis and stress (g) on ​​the vertical axis, the moment when the stress (g) instantaneously turns negative and then turns positive again was defined as a "peak," and the number of peaks where the negative stress (g) exceeds a threshold was defined as the peak count. The threshold was set at 3g. The number of peaks and the disturbance of the stress waveform in the above measurement serve as indicators of the food's disintegration and brittleness in the mouth. The following commercially available ice creams were measured using the same method as above, and the results were as follows: ・Morinaga Milk Industry Co., Ltd. "MOW Vanilla": Peak count 2 ・Meiji Co., Ltd. "Essel Super Cup Ultra Vanilla": Peak count 2 ・Lotte Co., Ltd. "Soh Vanilla": Peak count 24

[0076] <Examples 1-7> (Preparation of Yogurt Mix) All ingredients except the starter were mixed according to the formulations shown in Table 1, stirred at 60°C for 15 minutes to dissolve, and then homogenized using a homogenizer to obtain a prepared milk solution. The homogenization conditions were 65°C, second stage pressure of 5 MPa, and total pressure of 10 MPa. The obtained prepared milk solution was heat-sterilized at 77°C for 15 seconds, cooled to the fermentation temperature, and then the starter was added to start fermentation. The starter used was lactic acid bacteria (Christian Hansen, FD-DVS YF-3331) and bifidobacteria (Bifidobacterium longum). Once the predetermined acidity was reached, the fermentation was terminated by cooling to 10°C while crushing the curd by stirring, and a yogurt mix was obtained. In Table 1, "appropriate amount" of starter means the amount that will reach the predetermined acidity within 8 hours.

[0077] (Preparation of Ice Mix) All ingredients were mixed according to the formulation shown in Table 2, stirred at 70°C for 20 minutes to dissolve, and then homogenized. Next, the mixture was heat-sterilized at 88°C for 15 seconds and cooled to 5°C to obtain the ice mix.

[0078] (Preparation of raw material mix) The yogurt mix and ice cream mix were mixed in the proportions shown in Table 3 to obtain the raw material mix.

[0079] (Preparation of fermented milk-containing frozen dessert) The raw material mix was supplied to a continuous freezer, and the partially frozen product discharged from the outlet of the continuous freezer was filled into 135 mL cup containers. The containers were then held at -35°C for 40 minutes or more to harden, obtaining fermented milk-containing frozen dessert in cup containers. In each example, the overrun (set value) and temperature (also called the filling temperature) of the partially frozen product discharged from the continuous freezer were set to the values ​​shown in Table 4.

[0080] <Comparative Examples 1-3> The following commercially available frozen yogurts containing fermented milk were prepared for comparison. • Comparative Example 1: Frozen yogurt manufactured by Aeon. • Comparative Example 2: Frozen yogurt manufactured by Meito. • Comparative Example 3: Frozen yogurt manufactured by Ministop.

[0081] Table 4 shows the size of ice crystals and peak counts for each example of frozen dessert containing fermented milk. In Table 4, the milk fat content and non-fat milk solids for Comparative Examples 1-3 are stated values, while all other values ​​are measured values.

[0082]

[0083]

[0084]

[0085]

[0086] The fermented milk-containing frozen desserts of Examples 1 to 7 had a peak count of 14 or less and exhibited excellent smoothness of texture. On the other hand, the fermented milk-containing frozen dessert of Comparative Example 1, which had an overrun of more than 80%, and the fermented milk-containing frozen desserts of Comparative Examples 2 and 3, which had a median ice crystal diameter of more than 60 μm, were inferior in terms of smoothness of texture.

[0087] The present invention also has the following aspects as another aspect:

[11] A fermented milk-containing frozen dessert having an overrun of 25% or more and 80% or less, and a median ice crystal diameter of 20 μm or more and 60 μm or less.

[12] The fermented milk-containing frozen dessert according to

[11] , which is frozen yogurt.

[13] The fermented milk-containing frozen dessert according to

[11] or

[12] , which contains a propylene glycol fatty acid ester.

[14] The fermented milk-containing frozen dessert according to

[13] , wherein the propylene glycol fatty acid ester is 0.05% by mass or more and 0.3% by mass or less with respect to the total mass of the fermented milk-containing frozen dessert.

[15] The fermented milk-containing frozen dessert according to any one of

[11] to

[14] , wherein the fermented milk content is 60% by mass or more and 80% by mass or less with respect to the total mass of the fermented milk-containing frozen dessert.

[16] The fermented milk-containing frozen dessert according to any one of

[11] to

[15] , which contains Bifidobacterium bacteria.

[17] The fermented milk-containing frozen dessert according to any one of

[11] to

[16] , wherein the fermented milk-containing frozen dessert contains milk fat, and the amount of milk fat is 3.3% by mass or more and 9.0% by mass or less with respect to the total mass of the fermented milk-containing frozen dessert.

[18] The fermented milk-containing frozen dessert according to any one of

[11] to

[17] , wherein the solid content of the fermented milk-containing frozen dessert is 26% by mass or more and 34% by mass or less.

[19] The fermented milk-containing frozen dessert according to any one of

[11] to

[18] , wherein the freezing point of the fermented milk-containing frozen dessert is -3.1°C or more and -2.5°C or less.

[20] A method for producing a frozen dessert containing fermented milk, comprising the steps of: mixing fermented milk with frozen dessert ingredients other than fermented milk to obtain a raw material liquid; freezing the raw material liquid to obtain a partially frozen product; shaping the partially frozen product; and hardening the shaped partially frozen product, wherein in the step of freezing the raw material liquid, the overrun of the partially frozen product is 25% or more and 80% or less; and in the step of shaping the partially frozen product, the temperature of the partially frozen product is set to be at or above the freezing point of the partially frozen product and below the freezing point.

[21] The method for producing a frozen dessert containing fermented milk according to

[20] , wherein the frozen dessert containing fermented milk is frozen yogurt.

[22] The method for producing a frozen dessert containing fermented milk according to

[20] or

[21] , wherein the frozen dessert ingredients include propylene glycol fatty acid ester.

[23] The frozen dessert containing fermented milk according to

[22] , wherein the propylene glycol fatty acid ester is 0.05% by mass or more and 0.3% by mass or less with respect to the total mass of the raw material liquid.

[24] The method for producing a frozen dessert containing fermented milk according to any one of

[20] to

[23] , wherein the content of the fermented milk is 60% by mass or more and 80% by mass or less with respect to the total mass of the raw material liquid.

[25] The method for producing a frozen dessert containing fermented milk according to any one of

[20] to

[24] , wherein at least one of the fermented milk and the frozen dessert raw material contains bacteria of the genus Bifidobacterium.

[26] The frozen dessert containing fermented milk according to any one of

[20] to

[25] , wherein the frozen dessert raw material contains milk fat, and the milk fat content is 3.3% by mass or more and 9.0% by mass or less with respect to the total mass of the frozen dessert raw material.

[27] The frozen dessert containing fermented milk according to any one of

[20] to

[26] , wherein the solid content of the frozen dessert raw material is 26% by mass or more and 34% by mass or less.

[28] The frozen dessert containing fermented milk, wherein the freezing point of the frozen dessert is -3.1°C or higher and -2.5°C or lower, according to any one of

[20] to

[27] .

[0088] According to the present invention as disclosed here, it is possible to provide a fermented milk-containing frozen dessert with excellent smoothness of texture and a method for producing the same.

Claims

1. A frozen dessert containing fermented milk, wherein the overrun is 80% or less and the median diameter of the ice crystals is 60 μm or less.

2. A frozen yogurt containing fermented milk, as described in claim 1.

3. A fermented milk-containing frozen dessert according to claim 1 or 2, comprising a propylene glycol fatty acid ester.

4. The fermented milk-containing frozen dessert according to claim 1 or 2, wherein the fermented milk content is 60 to 80% by mass of the total mass of the fermented milk-containing frozen dessert.

5. A fermented milk-containing frozen dessert according to claim 1 or 2, which contains bacteria of the genus Bifidobacterium.

6. A method for producing a frozen dessert containing fermented milk, comprising the steps of: mixing fermented milk with frozen dessert ingredients other than fermented milk to obtain a raw material liquid; freezing the raw material liquid to obtain a partially frozen product; shaping the partially frozen product; and hardening the shaped partially frozen product, wherein in the step of freezing the raw material liquid, the overrun of the partially frozen product is set to 80% or less; and in the step of shaping the partially frozen product, the temperature of the partially frozen product is set to be at or above the freezing point of the partially frozen product and below the freezing point.

7. The method for producing a fermented milk-containing frozen dessert according to claim 6, wherein the fermented milk-containing frozen dessert is frozen yogurt.

8. The method for producing a fermented milk-containing frozen dessert according to claim 6 or 7, wherein the frozen dessert ingredients include a propylene glycol fatty acid ester.

9. The method for producing a frozen dessert containing fermented milk according to claim 6 or 7, wherein the content of the fermented milk is 60 to 80% by mass relative to the total mass of the raw material liquid.

10. A method for producing a frozen dessert containing fermented milk according to claim 6 or 7, wherein at least one of the fermented milk and the frozen dessert ingredients contains bacteria of the genus Bifidobacterium.

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