HK1188089B - Fermented milk with improved flavor and method for producing same - Google Patents

Abstract

The purpose of the present invention is to improve the flavor of a fermented milk by employing a lactose degradation step and, further, adding a whey powder to a starting material to thereby control the balance between the sweetness and sourness of the fermented milk. A method for producing a fermented milk, said method comprising a step for adding a whey powder to a starting milk and a step for degrading lactose in the starting milk by a lactase. By use of the production method according to the present invention, a fermented milk, which can be appropriately taken without using a sweetener such as sucrose and has a novel flavor, can be obtained.

Description

Fermented milk with improved taste and method for producing same

Technical Field

The present invention relates to a method for improving the taste of fermented milk.

Background

Some prior arts have studied methods for improving the taste and quality of drinks and foods such as fermented milk. A method of preventing the flavor of drinks and foods from being volatilized and masking off the unpleasant odor by adding whey protein or the like and solving the problem of containing additives is disclosed (patent document 1). Further, a method of adding whey powder and a whey protein concentrate to a fermented milk raw material has been disclosed in order to solve problems such as a taste caused by the addition of a stabilizer (patent document 2). These methods are mainly intended to improve the quality deterioration of beverages and foods such as fermented milk due to additives.

On the other hand, as a method for improving the taste of fermented milk, a method for increasing the sweetness of fermented milk has been studied. The sweetness of fermented milk is usually obtained by adding granulated sugar such as fine granulated sugar after fermentation. However, the sweetness of fermented milk can be increased by decomposing lactose into monosaccharides such as glucose and galactose by lactase (lactase).

For example, patent document 3 discloses fermented milk with a low lactose content whose sweetness is increased by a lactase; patent document 4 discloses a method for producing a fermented milk in which the taste and quality of a fermented milk after lactose decomposition treatment can be fixed by subjecting a raw milk to a deoxidation treatment.

Patent document

Patent document 1: japanese patent No. 3272453

Patent document 2: japanese unexamined patent publication No. 6-14708

Patent document 3: japanese patent No. 3389377

Patent document 4: WO2010/098086 publication

However, even in the method for producing fermented milk including the lactose degradation step, there is a limit to increase the sweetness, and the problem of improving the taste of fermented milk cannot be solved.

Disclosure of Invention

Therefore, an object of the present invention is to provide a method for improving the taste of fermented milk and a fermented milk with improved taste.

In view of the problems of the prior art, the present inventors have intensively studied and found that in a method for producing a fermented milk including a step of decomposing lactose in a raw milk by a lactose-decomposing enzyme, a balance between sweetness and sourness of the fermented milk can be adjusted by mixing a whey powder with the raw material, and have completed the present invention. Further, it has been found that by using the method for producing fermented milk of the present invention, fermented milk having a new taste and suitable for absorption can be obtained without using a sweetener such as granulated sugar.

Namely, the present invention provides the following [1] to [8 ].

[1] A method for producing fermented milk, comprising a step of mixing whey powder with raw milk and a step of decomposing lactose in the raw milk with a lactase.

[2] The method according to [1], wherein the whey powder is 1.0 wt% or more and 4.0 wt% or less.

[3] The method according to [1] or [2], wherein the whey powder has a lactose content of 65 wt% or more and 95 wt% or less and a whey protein content of 5.0 wt% or more and 20 wt% or less.

[4] The method according to any one of [1] to [3], wherein the lactose in the raw milk is 5.0 wt% or more and 9.0 wt% or less, and/or the lactose decomposition rate is 30% or more and 100% or less.

[5] A fermented milk produced by the method according to any one of [1] to [4 ].

[6] The fermented milk according to [5], wherein the glucose content is 0.5% by weight or more and 4.0% by weight or less, and the pH is 3.8 or more and 5.5 or less.

[7] The fermented milk according to [5] or [6], which is a yogurt drink.

[8] The fermented milk according to any one of [5] to [7], which is not added with a sweetener.

According to the method for producing fermented milk of the present invention, lactose in the raw milk is decomposed into glucose and galactose having stronger sweetness by the lactase, thereby increasing the sweetness of the fermented milk. Further, by adding whey powder to the raw milk, lactose contained in the whey powder is decomposed by the lactase, so that a sweeter taste can be obtained. Further, since lactose is substantially decomposed, problems relating to lactose indigestion are unlikely to occur.

Further, since whey powder contains salts such as sodium salt and potassium salt at a high concentration, a shielding effect of the salts against sourness can be expected, and sweetness can be effectively generated. Further, by the unique taste of whey protein, not only sweetness but also sourness can be suppressed, that is, the balance of sweetness and sourness of fermented milk can be adjusted at the same time. Therefore, the whey powder added to the fermented milk can sufficiently exert its effect even in a small amount, and therefore the addition does not adversely affect the product quality.

Further, fermented milk exhibiting sufficient sweetness can be produced in a short time as compared with the prior art lactose decomposition treatment.

The fermented milk of the present invention has a better sweet-sour balance than the conventional methods, and can be provided without adding a sweetener after fermentation even in a beverage type yogurt having a better sweet taste than sour taste.

Further, even with hard yogurt having strong sour taste, which has been difficult to use for yogurt drinks, a yogurt drink having good taste and drinkability can be produced without adding a sweetener. Therefore, the present invention can provide a yogurt drink having a new taste and being easy to drink, in which the balance between sweetness and sourness is adjusted, without adding a sweetener.

Detailed Description

The method for producing fermented milk of the present invention includes a step of mixing whey powder into raw milk (whey powder mixing step) and a step of decomposing lactose in the raw milk with a lactase (lactose decomposition step).

Fermented milk

In the present specification, "fermented milk" includes "fermented milk", "dairy product lactic acid bacteria beverage" and "lactic acid bacteria beverage" defined by the provincial (dairy provincial) such as the standards of ingredients of milk and dairy products, and also includes yogurt and the like.

For example, the fermented milk refers to fermented milk obtained by fermenting milk including fresh milk, cow milk, particularly cow milk, fresh goat milk, pasteurized goat milk, fresh goat milk, component-adjusted milk, low-fat milk, fat-free milk, processed milk, or milk including solid components of fat-free milk equivalent to or more than that of the milk, with lactic acid bacteria or yeast to form a paste or liquid or freezing the paste or liquid, and includes hard yogurt, soft yogurt (paste fermented milk), or yogurt drink (liquid fermented milk).

The preferred fermented milk of the present invention is a yogurt drink. In general, hard yogurts such as plain yogurts are produced by filling a container with a raw material and then fermenting (post-fermentation). On the other hand, soft yogurt and yogurt drinks are produced by micronizing fermented milk, homogenizing the same, and then filling the same in a container (pre-fermentation).

Raw milk

The "raw milk" is a raw material of fermented milk such as yogurt, and is therefore also referred to as yogurt mix, fermented milk mix, and the like. In the present invention, known raw milk can be suitably used. The raw milk comprises raw milk before sterilization and raw milk after sterilization.

Specific raw materials of the raw milk may include water, fresh milk, sterilized milk, skim milk, whole milk powder, skim milk powder, buttermilk, butter, cream, Whey Protein Concentrate (WPC), Whey Protein Isolate (WPI), α -lactalbumin (La), β -lactoglobulin (Lg), and the like. Heated gelatin may be appropriately added in advance. Lactose-degrading enzymes may be added in advance to properly degrade lactose. The starting milk is known and can be prepared according to known methods.

In the present specification,% means weight% (w/w).

Preferred raw materials for the present invention include, but are not limited to, fresh milk, skim milk, and cream. The raw milk used in the present invention preferably has a solid non-fat content of 6.0% to 10.0%, more preferably 7.0% to 9.0%. The fat component is preferably 0.5% or more and 4.0% or less, more preferably 1.0% or more and 3.0% or less.

The content of lactose in the raw material before fermentation is preferably 4.0% to 10.0%, more preferably 5.0% to 9.0%.

The raw materials, apparatus and production conditions for producing fermented milk are disclosed in Japanese patent laid-open Nos. 2004-180526, 2005-176603, 2006-288309, 6025008, 5482723, 5096731 and 4938973, for example. For example, as an apparatus for producing fermented milk, a fermentation chamber for fermenting after filling a post-fermented product, a fermentation tank for fermenting a pre-fermented product, a line filter and a homogenizer for pulverizing fermented milk curd, and the like; as the production conditions, a deoxidation apparatus or the like can be suitably employed.

In one aspect of the present invention, the process for producing fermented milk may include a deoxidation treatment process of deoxidizing the raw milk. The deoxidation step is a step of removing oxygen present in the raw milk by, for example, mixing an inert gas into the raw milk or degassing by low pressure or vacuum. This procedure suggests that proteins can be protected in addition to oxygen removal.

In the deoxidation step, for example, a known apparatus for replacing dissolved oxygen in the raw material milk with an inert gas can be suitably used, and the dissolved oxygen in the raw material milk can be expelled by the inert gas. Such known devices are disclosed in Japanese patent laid-open Nos. 2001-78665, 2001-9206, and 2005-110527.

The "inert gas" may be a gas such as nitrogen gas in addition to a rare gas such as helium gas, neon gas, argon gas, or xenon gas.

Further, as an alternative to the incorporation of the inert gas, oxygen dissolved in the raw milk may be removed by degassing. Such a degasser is disclosed in Japanese patent laid-open publication Nos. 2002-370006 and 2005-304390.

The deoxidation step may be carried out, for example, until the amount of oxygen dissolved in the raw milk (dissolved oxygen concentration, DO) becomes 5.0ppm or less, preferably 3.0ppm or less, and more preferably 2.0ppm or less.

Whey powder mixing process

The "whey powder mixing step" is a step of mixing or adding whey powder to raw milk. The term "whey powder" (whey powder) as used in the present specification includes: powdered whey is prepared by removing almost all of water from whey (whey) obtained by fermenting milk defined in accordance with the David province with lactic acid bacteria or by adding enzymes or acids to milk. Whey refers to a water-soluble component remaining in, for example, milk after removing fat, casein, fat-soluble vitamins, and the like. Whey is usually cheese whey or rennet whey (or also referred to as sweet whey) obtained as a by-product in the manufacture of natural cheese or rennet casein; and casein whey, quark whey (or also called acid whey) obtained when producing acid casein or quark from skim milk. The main components of whey include proteins (beta-lactoglobulin, alpha-lactalbumin, etc.), lactose, water-soluble vitamins, and salts (mineral components).

Examples of the "Whey-related products" include concentrated Whey obtained by concentrating Whey, Whey powder obtained by drying Whey, Whey protein concentrate (also referred to as "Whey protein concentrate", WPC) obtained by concentrating main proteins of Whey by an Ultrafiltration (UF) method or the like and then drying the concentrate, defatted WPC (low fat high protein) obtained by removing fat from Whey by a Microfiltration (MF) method, a centrifugal separation method or the like and then concentrating the concentrate by an UF method and then drying the concentrate, Whey protein isolate (also referred to as "Whey protein isolate, WPI) obtained by selectively fractionating main proteins of Whey by an ion exchange resin method, a gel filtration method or the like and then drying the concentrate), desalted Whey obtained by desalting main proteins of Whey by a Nanofiltration (NF) method, an electrodialysis method or the like and then drying the concentrate, Whey-derived minerals obtained by precipitating the minerals derived from Whey and then concentrating the concentrate by a centrifugal method or the like Clear and the like.

In addition, whey or a composition containing whey components can be used and added in the same manner as mixing whey powder. For example, concentrated whey may be used which is concentrated and made into a solid form. In addition, a whey protein concentrate obtained by removing almost all of the water from lactose-removed whey to obtain a powder, or the like can also be used.

In the present invention, whey powder is preferably used. The whey powder is preferably mixed in the raw milk at a ratio of 1.0% to 4.0%, more preferably 1.5% to 3.0%. More preferably 1.7% or more and 2.8% or less, and still more preferably 1.8% or more and 2.3% or less. In the case where the amount of whey powder to be mixed is large, the taste of the fermented milk is impaired by the strong whey protein taste and the salty taste derived from whey powder, while the sweetness derived from lactose is strongly perceived, and therefore the effect of the implied sweetness which is desired to be produced in the present invention is reduced. In addition, when the amount of whey powder to be mixed is large, astringency derived from whey protein is strongly felt, and the quality is easily adversely affected; when the amount is too small, it is difficult to expect the effect of controlling sweetness and sourness.

The whey powder used in the present invention may be a sweet whey powder, a desalted whey powder, a concentrated whey powder, etc., and a sweet whey powder is preferably used. Further, these may be used in combination, or a commercially available product may be used.

The whey powder used in the present invention has the following composition: the solid content is preferably 90% to 100%, more preferably 95% to 100%. The whey protein is preferably 5.0% to 20%, more preferably 10% to 15%. Further, lactose is preferably 65% or more and 95% or less, more preferably 70% or more and 90% or less. The ash content is preferably 1% or more and 15% or less, more preferably 5% or more and 10% or less.

Further, sodium is preferably contained in an amount of 300mg to 1200mg per 100g of whey powder, and more preferably 500mg to 1000 mg. Further, potassium is preferably contained in an amount of 1500mg or more and 4000mg or less, more preferably 2000mg or more and 3000mg or less, per 100g of whey powder.

In addition, as described above, whey or a composition containing whey components may be used, and added in the same manner as in the mixing of these components.

Fermentation step

To produce fermented milk, raw milk is fermented. The fermentation step of the raw milk may include two-stage fermentation and the like. Fermented milk having a commercial value can be obtained through the fermentation step. In the present invention, it is preferable to mix a starter in the raw milk and perform fermentation.

As the fermentation agent, a known fermentation agent can be suitably used. Preferred examples of the lactic acid bacteria starter include lactic acid bacteria starter, and one or more of other lactic acid bacteria and yeasts commonly used in the production of fermented milk, such as lactobacillus bulgaricus (l.bulgaricus), streptococcus thermophilus (s.thermophilus), lactococcus lactis (l.lactis), lactobacillus gasseri (l.gasseri), and Bifidobacterium (Bifidobacterium), can be used as the lactic acid bacteria starter.

Among these, according to the international food code standard, as the yogurt starter, a starter based on a standardized mixed starter of lactobacillus bulgaricus (l.bulgaricus) and streptococcus thermophilus (s.thermophilus) is preferable. Based on the yogurt starter culture, other lactic acid bacteria such as lactobacillus gasseri (l.gasseri) and Bifidobacterium (Bifidobacterium) may be further added to the desired fermented milk. The amount of the fermentation agent to be added may be appropriately selected from those already used in known methods for producing fermented milk. The inoculation method of the fermentation agent may be performed according to a known method used in the production of fermented milk.

Lactose decomposition step

The "lactose degradation step" is a step in which lactose is degraded by a lactase. The lactase may be added at any stage of the manufacturing process. The lactase can be added into raw milk and/or whey powder.

In general, from the viewpoint of reducing the risk of bacterial contamination, after lactose is decomposed, heat sterilization is performed at a low temperature to inactivate or kill enzymes, and then fermentation is performed.

On the other hand, in the present invention, the fermentation step may be performed by mixing a starter and a lactase into a yogurt mix (raw milk) and fermenting the enzyme-active component. Further, lactose or the like contained in the raw milk may be decomposed to generate an acid, thereby inactivating the enzyme. By this treatment, the lactose decomposition rate can be effectively increased.

In addition, when the starting milk is mixed with a starter and a lactase to ferment, the enzyme reaction is not required before the high-temperature heat sterilization, so that the production process of the fermented milk can be simplified and the original taste of the fermented milk can be maximized. Further, since the lactose degradation rate can be effectively increased in the treatment, it is not necessary to separately manage the lactose degradation rate and the degree of fermentation (change in acidity), and the product management becomes very easy.

Therefore, in the present invention, it is preferable to add the lactase together with the starter to the raw milk. However, the lactase may be added before the addition of the fermentation product, or may be added simultaneously with or after the addition of the fermentation product. In the case of using raw milk mixed with a lactase and a fermentation agent, lactose in the raw milk is decomposed with the progress of the fermentation step.

The lactase may be added before the deoxidation treatment step, or may be added after the deoxidation treatment step.

The lactase of the present invention has an optimum pH for its activity in the neutral range, and is an enzyme which is inactivated in the acidic range, and preferably can decompose lactose in the active state. An example of such an enzyme is a lactase disclosed in patent document 3. Examples of the lactase include those derived from bacteria and yeast. Further, the optimum pH for activity is 6.3 or more and 7.5 or less and the inactivation pH is 6.0 or more and 4.0 or less. Further, as the lactolytic enzyme, a lactolytic enzyme derived from Kluyveromyces lactis (Kluyveromyces lactis) or a lactolytic enzyme derived from Kluyveromyces fragilis (Kluyveromyces fragilis) is preferable. The lactose decomposing enzyme derived from Kluyveromyces lactis contains a lactose decomposing enzyme derived from Kluyveromyces lactis in addition to Kluyveromyces lactis itself. Further, lactolytic enzymes are commercially available, and examples of the commercially available lactolytic enzymes include ラクターゼ F (manufactured by Tianye エンザイム Co., Ltd.), ラクトレス L-3 (manufactured by Dazao Kaisha Co., Ltd.), and ラクトレス L-10 (manufactured by Dazao Kaisha Co., Ltd.).

Fermentation and lactose decomposition conditions

The fermentation conditions such as fermentation temperature can be appropriately adjusted in consideration of the kind of lactic acid bacteria to be added to the raw milk, the desired taste of the fermented milk, and the like. As a specific example, the temperature in the fermentation chamber (fermentation temperature) is maintained at 30 ℃ or higher and 50 ℃ or lower. At such a temperature, usually, the lactic acid bacteria are easy to move, and thus the fermentation can be efficiently performed. The fermentation temperature in this case is more preferably 40 ℃ to 45 ℃ inclusive, and still more preferably 41 ℃ to 44 ℃ inclusive.

The fermentation time may be appropriately adjusted depending on the fermentation agent, the fermentation temperature, and the like, and specifically may be 1 hour or more and 5 hours or less, and may be 2 hours or more and 4 hours or less.

In addition, in general, if the lactose decomposition rate in the raw material is 65% or more, fermented milk with good taste can be obtained. However, according to the production method of the present invention, the balance between sweetness and sourness is adjusted by adding whey powder, and sufficient sweetness can be obtained even if the lactose decomposition rate is low. Therefore, in the present invention, the lactose degradation rate may be 30% or more and 100% or less, and for increasing the sweetness, 60% or more and 100% or less may be used.

In addition, the lactose degradation step in the raw material is carried out by any method before sterilization or simultaneously with fermentation. Generally, the temperature at which lactose is decomposed may be 0 ℃ or higher and 55 ℃ or lower, preferably 30 ℃ or higher and 50 ℃ or lower, and more preferably 40 ℃ or higher and 45 ℃ or lower, at which the activity of the lactase is maintained. The lactose degradation time is usually maintained at a temperature of 40 ℃ or more and 45 ℃ or less for 1 hour or more, which is suitable for the lactose-degrading enzyme. However, according to the present invention, the time for the lactose decomposition treatment can be shortened as compared with the conventional techniques, and the time for the lactose decomposition at 40 ℃ to 45 ℃ can be 15 minutes to 1 hour, preferably 30 minutes to 45 minutes.

Taste of fermented milk, etc

In the present specification, the term "sweet-sour balance" is a term indicating the intensity balance of sweetness and sourness, and is also one of the indicators of palatability. The term "adjustment of sweet-sour balance" means that the sweet-sour balance is adjusted to a preferable range in terms of absorption, and includes, for example, adjustment of taste by enhancing or reducing sweet taste and/or enhancing or reducing sour taste with the aim of improving conventional poor evaluations.

Further, the adjustment of the sweet-sour balance does not always involve a change in physical property parameter values of the index such as sweetness and sourness such as sugar (or brix) and pH, and does not always involve a change in individual taste index such as sweetness and sourness in a sensory test or the like.

The taste of the fermented milk of the present invention is evaluated by sensory tests and the like. For example, as the analytical sensory evaluation, a two-point test, a three-point test, a ranking test, or other test type tests can be used. Furthermore, the evaluation can be performed by a descriptive test such as a scoring method or a sectioning method, or by a Quantitative Description Analysis (QDA).

For example, the evaluation of the degree of sweet-sour balance may be compared with a standard as a relative evaluation or as an absolute evaluation in five grades depending on the degree of taste index such as the degree of sweetness and the degree of sourness. For the panel, for example, in the case of using a professional panel, at least 5 persons, and usually 10 persons or more and 15 persons or less can be performed.

In one aspect of the present invention, the sweet-sour balance of fermented milk can be improved while keeping individual taste indexes such as sweetness and sourness.

In addition, the mouthfeel of the fermented milk can be reduced by the present invention. Especially for yogurt drinks and the like, the aftertaste in the mouth and/or the drinkability (passage of food through the throat) can be improved. Thus, fermented milk having improved taste can be provided.

The fermented milk of the present invention is not limited, and can be provided as it is without adding granulated sugar (fine granulated sugar or the like) as a sweetener other than the raw material. Further, the present invention provides a new yoghurt drink which improves the taste and mouthfeel of fermented milk and which is easy to drink with a balanced sweetness and sourness.

The fermented milk of the present invention preferably has a glucose content of 0.5% to 4.0%, more preferably 1.0% to 3.0%, and still more preferably 1.5% to 2.5%. The pH that can be an index of sourness is preferably 3.8 or more and 5.5 or less, more preferably 4.0 or more and 5.0 or less, and further preferably 4.3 or more and 4.8 or less.

Examples

Example 1

Skim milk powder (trade name: "tomorrow skim milk powder", manufactured by tomorrow ) containing 1% of fat component, 34% of protein, and 54% of lactose, milk (trade name: "tomorrow milk", manufactured by tomorrow ) containing 3.9% of fat component, 3.2% of protein, and 4.7% of lactose, and whey powder (trade name: "tomorrow ホエイパウダー", manufactured by tomorrow ) containing 1.0% of fat component, 12% of protein, 76% of lactose, 97% of solid component, 8.6% of ash, 0.7% of sodium, and 2.5% of potassium were used, and prepared in the formulation ratios shown in table 1. Lactase (lactase) (trade name: GODO-YNL, refined with Korea) and lactobacillus leaven (Lactobacillus bulgaricus 2038 strain and Streptococcus thermophilus 1131 strain isolated from Yongzhi milk , Yongzhi ブルガリアヨーグルト (trade name)) were added at the same time, fermented at 43 ℃ to pH4.4 (about 3 hours), and the resulting fermented milk curd was pulverized with a filter and cooled. As a comparative control, instead of whey powder, crude LACTOSE (LACTOSE content: 99.5%, trade name: "LACTOSE gradeur", manufactured by FIRST DISTRICT Assistant Co., Ltd.) was used, the LACTOSE content was adjusted to be the same as in example 1, and fermentation and curd pulverization were carried out in the same manner as in example 1 to obtain comparative example 1.

TABLE 1

The compositions and analysis values of example 1 and comparative example 1 shown in table 1 are shown in table 2. In addition, the contents of fat, protein, lactose and glucose, and acidity of lactic acid were measured by the Gabeb method, the Kjeldahl method, the enzymatic method (F-kit: manufactured by JK インターナショナル), and the titration method, respectively.

TABLE 2

The results given by 12 professional reviews by sensory test (five-grade scoring) for example 1 and comparative example 1 are shown in table 3. The fermented milk was kept in a refrigerated state for 1 day after the production, and was sufficiently stirred before the trial to provide about 50mL of each of them. The degree of sweetness and the degree of sourness were evaluated on five levels of strong (5), slightly strong (4), normal (3), slightly weak (2) and weak (1), the evaluation of the balance of sweetness and sourness, the drinkability and the aftertaste in the mouth was evaluated on five levels of good (5), slightly good (4), middle (3), slightly poor (2) and poor (1), and the degree of mouthfeel was evaluated on five levels of heavy (5), slightly heavy (4), middle (3), slightly light (2) and light (1).

TABLE 3

**p＜0.01

Although the pH as an index of sourness and the glucose content as a sweetness source were the same in example 1 and comparative example 1, a significant difference (p < 0.01) was observed in evaluation of the degree of sourness and the sweetness-sourness balance, and the effect of improving sourness and sweetness-sourness can be effectively produced by decomposition of lactose by using whey powder.

Example 2

Skim milk powder (trade name: "tomorrow skim milk powder", manufactured by tomorrow ) containing 1% of fat component, 34% of protein, and 54% of lactose, milk (trade name: "tomorrow milk", manufactured by tomorrow ) containing 3.9% of fat component, 3.2% of protein, and 4.7% of lactose, and whey powder (trade name: "tomorrow ホエイパウダー", manufactured by tomorrow ) containing 1.0% of fat component, 12% of protein, 76% of lactose, 97% of solid component, 8.6% of ash, 0.7% of sodium, and 2.5% of potassium were used, and prepared in the formulation ratios shown in table 4. Lactase (lactase) (trade name: GODO-YNL, Kogyo refined) and lactobacillus leaven (Lactobacillus bulgaricus 2038 strain and Streptococcus thermophilus 1131 strain isolated from Yongzhi milk "Yongzhi ブルガリアヨーグルト" (trade name)) were added at the same time, fermented at 43 ℃ to reach pH4.4 (about 3 hours), and the resulting fermented milk curd was pulverized with a filter and cooled. As a comparative control, skim milk powder was used instead of whey powder, the lactose content was adjusted to be the same as in example 2, fermentation was performed by the same method as in example 2, and curd was pulverized and cooled at a stage of reaching ph4.7 to obtain comparative example 2.

TABLE 4

The compositions and analysis values of example 2 and comparative example 2 shown in table 4 are shown in table 5.

TABLE 5

As in example 1, the results of example 2 and comparative example 2 given by 12 professional reviews by sensory test (five-grade scoring) are shown in table 6.

TABLE 6

**p＜0.01

The pH as an index of sourness was lower in example 2 than in comparative example 2, and the glucose content as an index of sweetness was the same. As a result of the sensory evaluation, a significant difference was observed in terms of the sweet-sour balance, and by mixing whey powder, a good sweet-sour balance was maintained even when the pH was low, and a good fermented milk with little change in taste was provided even when the pH was lowered by the nature of lactic acid bacteria during storage.

Industrial applicability of the invention

The present invention relates to a method for improving the taste of fermented milk, which can provide fermented milk suitable for drinking and eating without feeling sour taste even without adding a sweetener such as granulated sugar.

Claims (7)

1. A method for producing fermented milk, comprising a step of mixing whey powder with raw milk and a step of decomposing lactose in the raw milk with a lactase,

wherein the whey powder has a lactose content of 65-95 wt% and a whey protein content of 5.0-20 wt%,

wherein the whey powder is mixed in the raw milk in an amount of 1.0 to 4.0 wt%.

2. The method according to claim 1, wherein the lactose in the raw milk is 5.0 wt% or more and 9.0 wt% or less, and/or the lactose degradation rate is 30% or more and 100% or less.

3. The method according to claim 1, wherein in the step of decomposing lactose, the lactose-decomposing enzyme and the fermentation agent are added together to the raw milk, and the decomposition and fermentation of lactose are performed simultaneously.

4. A fermented milk produced by the method according to any one of claims 1 to 3.

5. The fermented milk according to claim 4, wherein the glucose content is 0.5 wt% or more and 4.0 wt% or less, and the pH is 3.8 or more and 5.5 or less.

6. The fermented milk according to claim 4, wherein the fermented milk is a yogurt drink.

7. Fermented milk according to any of claims 4 to 6, wherein no sweetener is added to the fermented milk.