JP6463270B2 - Method for producing fermented milk with improved physical properties - Google Patents

Description

  The present invention has a smooth texture (texture), and changes in physical properties accompanying the aggregation of milk proteins that occur during refrigerated storage and distribution (generation of water separation, particle size of milk proteins (aggregated particles)) The present invention relates to a method for producing fermented milk of good quality in which increase or occurrence of roughness associated therewith is suppressed.

  In fermented milk typified by yogurt, it is known that proteins derived from milk aggregate during refrigerated storage and refrigerated transport (distribution), and the physical properties (tissue) change accordingly. Specifically, water separation occurs due to aggregation of milk protein, or milk protein particles generated by aggregation gradually increase over time, which causes roughness when put in the mouth, etc. It is known that both the appearance and the flavor deteriorate and the quality is lowered.

  In order to solve such a problem, Patent Document 1 proposes a method of blending a specific amount of whey hydrolyzate in raw material milk and fermenting it to produce fermented milk, followed by a homogenization treatment. According to the document, it is described that a fermented milk beverage (drink type yogurt) in which aggregation and precipitation of milk protein suspended particles are suppressed can be produced. Patent Document 2 proposes a method of homogenizing the same as described above after producing a fermented milk by blending a specific amount of high-purity whey protein into raw milk and fermenting it. For example, it is described that a soft type fermented milk having an appropriate viscosity and a smooth texture can be produced without using a thickener. Further, in Patent Documents 3 and 4, in the production of soft type fermented milk, by adopting a process of extruding a card of fermented milk from a mesh or nozzle having a predetermined pore size, fermentation with a smooth texture and texture It is described that milk can be produced. However, none of these methods can be applied to stationary type fermented milk (hard type yogurt, set type yogurt), and there is no teaching about the use of glucose oxidase.

  Patent Documents 5 to 8 disclose that fermented milk raw material mix with lactic acid bacteria starter and peroxidase are fermented to suppress whey separation and protein aggregation during storage and distribution. However, it is described that a fermented dairy product having a fine and smooth texture can be produced. However, neither of these documents teaches the use of glucose oxidase.

  Glucose oxidase has long been known to have antibacterial activity. This antibacterial action is due to glucose being oxidized by glucose oxidase to produce hydrogen peroxide. As a method for producing fermented milk using the antibacterial action of glucose oxidase, in Patent Document 9, in order to avoid antibody deactivation due to heating in the production of antibody-containing fermented food, glucose oxidase is added to raw milk with hydrogen peroxide. It is described that raw milk is sterilized by adding it as a generator and then fermented with lactic acid bacteria. However, in Patent Document 9, glucose oxidase is disclosed as a hydrogen peroxide generator, that is, a bactericidal agent, together with glucose as its substrate. Further, in the production method described in Patent Document 9, heat treatment at 63 ° C. or higher is contraindicated in order to avoid inactivation of the antibody, and there is no problem of milk protein aggregation in the first place. In other words, Patent Document 9 does not have a problem of suppressing changes in physical properties associated with milk protein aggregation, and does not suggest the use of glucose oxidase.

  On the other hand, in Patent Document 10, in addition to glucose oxidase, glucose oxidase substrate (glucose) or a component serving as the substrate is blended in a ratio of a certain amount or more in raw material milk, so that physical properties associated with milk protein aggregation can be obtained. It is described that fermented milk of good quality can be produced in which changes (generation of water separation, increase in milk protein particle diameter, or generation of roughness associated therewith) are suppressed. However, by blending glucose oxidase alone into the raw milk, that is, without blending glucose oxidase substrate (glucose) and the component to be the substrate into the raw milk, the desired effect [with milk protein aggregation] There is no description or suggestion that a change in physical properties (inhibition of water separation, increase in milk protein particle size, or accompanying roughness) can be obtained.

JP 2007-6738 A Japanese Patent Laid-Open No. 07-000104 WO2006 / 057265 pamphlet WO2006 / 057266 pamphlet JP 62-228224 A Japanese Patent Laid-Open No. 06-276933 JP-A-10-262550 Japanese Patent Laid-Open No. 10-099019 JP 2007-053930 A WO2012 / 121090 pamphlet

  The present invention is fermented milk in which changes in physical properties associated with milk protein aggregation occurring during refrigerated storage and distribution are suppressed, specifically, generation of water separation, increase in the particle diameter of milk protein (aggregated particles), Or it aims at providing the manufacturing method of fermented milk in which generation | occurrence | production of the roughening accompanying it is suppressed. Moreover, this invention aims at providing the method of suppressing said physical property change accompanying aggregation of milk protein about fermented milk.

  The inventors of the present invention have made extensive studies to solve the above-described problems. As a result, in the process of producing fermented milk, glucose is not added to the raw material milk without adding (compounding) a component that produces glucose. By adding oxidase and allowing it to act, water separation and milk protein (aggregated particle) particle size increase over time accompanying milk protein aggregation are significantly suppressed compared to when glucose oxidase is not added. In addition, the increase in hardness over time and the decrease in viscosity over time observed in fermented milk produced without the addition of glucose oxidase are remarkably suppressed, and it is smooth and has good stickiness (stringiness) It was found that a fermented milk with a smooth texture (texture) can be obtained (see Experimental Example 1 described later). Moreover, it discovered that the stickiness (stringiness feeling) of the said fermented milk became one factor which brings a rich feeling to fermented milk combined with the fat content of fermented milk (refer Experimental example 2 mentioned later). Furthermore, in fermented milk produced by adding glucose oxidase, compared with fermented milk produced by adding glucose oxidase together with glucose as a substrate and components that produce glucose, time-dependent water separation under refrigerated conditions It was found that generation and increase of coagulated particles over time were significantly suppressed, and a certain level of stability was provided immediately after production (see Experimental Example 1 described later).

  Fermented milk with the stability of these physical properties can be delivered or stored (store display) under refrigerated conditions until it reaches the consumer's hands immediately after production. The present invention has been completed by confirming that it possesses the appropriate physical properties and good flavor required for fermented milk without impairing the flavor.

  That is, this invention relates to the invention of the aspect hung up below.

(I) Method for producing fermented milk with improved physical properties (I-1) (1) A step of preparing a fermented milk mix using milk raw materials,
(2) A method for producing fermented milk comprising a step of heat-sterilizing a fermented milk mix, and (3) adding (compounding) a starter to the heat-sterilized fermented milk mix and fermenting the mixture.
In the steps (1) to (3), at least one of the following (A) to (C) is performed:
(A) Fermented milk having a glucose concentration of 0.05% by weight or less, preferably 0.04% by weight or less, more preferably 0.03% by weight or less, and further preferably 0.02% by weight or less in the step (1). A process of adding glucose oxidase to the mix to prepare a fermented milk mix under the conditions of the glucose concentration,
(B) Before the step (3), the heat-sterilized glucose concentration is 0.05% by weight or less, preferably 0.04% by weight or less, more preferably 0.03% by weight or less, and further preferably 0.02% by weight. A process of adding glucose oxidase to a fermented milk mix of less than
(C) After step (3), the glucose concentration prepared in step (3) is 0.05% by weight or less, preferably 0.04% by weight or less, more preferably 0.03% by weight or less, more preferably A process of adding glucose oxidase to 0.02% by weight or less of fermented milk.

  (I-2) The production method according to (I-1), wherein the treatment (A) is performed in the step (1), and the heat sterilization temperature in the step (2) is 65 ° C. or higher.

(I-3) The production method according to (I-1) or (I-2), wherein Bulgarian (Lactobacillus bulg aricus) and Thermophilus (Streptococcus thermophilus) are used in combination as a starter.

  (I-4) Compared with fermented milk produced without using glucose oxidase and / or fermented milk produced with glucose oxidase at a glucose concentration of 1% by weight or more, preferably 3% by weight or more. The production method according to any one of (I-1) to (I-3), which is a method for producing fermented milk in which changes in physical properties associated with milk protein aggregation are suppressed.

  (I-5) The physical property change accompanying aggregation of milk protein is selected from the group consisting of generation of water separation (water separation), increase in particle diameter of milk protein (and / or fat), and generation of roughness of fermented milk tissue. The production method according to any one of (I-1) to (I-4), which is at least one of the following.

  (I-6) The change in physical properties accompanying the aggregation of milk protein is at least one selected from the group consisting of water separation (moisture separation) and an increase in milk protein (and / or fat) particle size. The production method according to any one of (I-1) to (I-4).

  (I-7) The method according to any one of (I-1) to (I-6), wherein unsterilized milk is used as a milk raw material.

  (I-8) The heat sterilization temperature in step (2) is 65 ° C. or higher, preferably 90 ° C. or higher, more preferably 90 to 100 ° C. Production method.

  (I-9) A method that does not include an operation of externally adding a substrate for glucose oxidase and a substance that can be a substrate for glucose oxidase as components other than milk ingredients through all steps (1) to (3) (I- 1) The production method according to any one of (I-8).

  (I-10) The production method according to any one of (I-1) to (I-9), wherein the fermented milk is yogurt.

  (I-11) The production method according to (I-10), wherein the fermented milk is a pre-fermented yogurt.

  (I-12) The fermented milk is a post-fermentation type yogurt, and the operation (A) is performed in the step (1), or the operation (B) is performed before the step (3). The production method according to (I-10), which is characterized.

  (I-13) The production method according to any one of (I-10) to (I-12), wherein the fermented milk is a soft type or drink type yogurt.

  (I-14) Fermented milk obtained by the production method according to any one of (I-1) to (I-13), in which changes in physical properties associated with milk protein aggregation are suppressed.

(II) Method for improving physical properties of fermented milk (II-1) (1) A step of preparing a fermented milk mix using milk raw materials,
(2) For fermented milk produced by a method having a step of heat-sterilizing the fermented milk mix and (3) adding (mixing) a starter to the heat-sterilized fermented milk mix and fermenting it, A method of suppressing the accompanying physical property change,
In the above steps (1) to (3), at least one of the following (A) to (C) is performed:
(A) Fermented milk having a glucose concentration of 0.05% by weight or less, preferably 0.04% by weight or less, more preferably 0.03% by weight or less, and further preferably 0.02% by weight or less in the step (1). A process of adding glucose oxidase to the mix to prepare a fermented milk mix under the conditions of the glucose concentration,
(B) Before the step (3), the heat-sterilized glucose concentration is 0.05% by weight or less, preferably 0.04% by weight or less, more preferably 0.03% by weight or less, and further preferably 0.02% by weight. A process of adding glucose oxidase to a fermented milk mix of less than
(C) After step (3), the glucose concentration prepared in step (3) is 0.05% by weight or less, preferably 0.04% by weight or less, more preferably 0.03% by weight or less, more preferably A process of adding glucose oxidase to 0.02% by weight or less of fermented milk.

  (II-2) The method according to (II-1), wherein the treatment (A) is performed in the step (1), and the heat sterilization temperature in the step (2) is 65 ° C. or higher.

(II-3) The method according to (II-1) or (II-2), wherein Bulgarian (Lactobacillus bulg aricus) and Thermophilus (Streptococcus thermophilus) are used in combination as a starter.

  (II-4) Compared with fermented milk produced without using glucose oxidase and / or fermented milk produced with glucose oxidase at a glucose concentration of 1% by weight or more, preferably 3% by weight or more. The method according to any one of (II-1) to (II-3), which is a method for suppressing changes in physical properties associated with milk protein aggregation.

  (II-5) The physical property change accompanying the aggregation of milk protein is selected from the group consisting of generation of water separation (water separation), increase in particle diameter of milk protein (and / or fat), and generation of roughness of fermented milk tissue. The method according to any one of (II-1) to (II-4), which is at least one of

  (II-6) The physical property change accompanying the aggregation of milk protein is at least one selected from the group consisting of water separation (separation of water) and increase in the particle diameter of milk protein (and / or fat). The method according to any one of II-1) to (II-4).

  (II-7) The method according to any one of (II-1) to (II-6), wherein unsterilized milk is used as a milk raw material.

  (II-8) The heat sterilization temperature in step (2) is 65 ° C. or higher, preferably 90 ° C. or higher, more preferably 90 to 100 ° C. Method.

  (II-9) A method that does not include an operation of externally adding a substrate for glucose oxidase and a substance that can be a substrate for glucose oxidase as components other than milk ingredients through all steps (1) to (3) (II- 1) The method described in any one of (II-8).

  (II-10) The method according to any one of (II-1) to (II-9), wherein the fermented milk is yogurt.

  (II-11) The production method according to (II-10), wherein the fermented milk is a pre-fermented yogurt.

  (II-12) The fermented milk is a post-fermentation type yogurt, and the operation (A) is performed in the step (1), or the operation (B) is performed before the step (3). A method according to (II-10), characterized in that

  (II-13) The method according to any one of (II-10) to (II-12), wherein the fermented milk is soft type or drink type yogurt.

  According to the method of the present invention, compared to the case where glucose oxidase is not added, changes in physical properties accompanying aggregation of milk protein, which occurs during refrigerated storage and distribution, specifically, generation of water separation, milk protein (coagulated particles) ), Or the occurrence of tissue roughness associated therewith can be significantly suppressed. In addition, according to the method of the present invention, compared to fermented milk produced by adding a substrate (glucose) or a substance that generates a substrate in addition to glucose oxidase to a milk raw material, particularly during refrigerated storage or distribution. Fermented milk can be produced in which water separation and milk protein (coagulated particles) generated are stably and significantly suppressed over time.

  The method of the present invention is a simple method that can be carried out while utilizing the current production process of fermented milk as it is, and does not impair the original flavor of fermented milk, and has appropriate physical properties and good flavor required for fermented milk. This is a method that can be stably maintained for a longer time.

I. Method for Producing Fermented Milk with Improved Physical Properties The method for producing fermented milk of the present invention includes at least the following three steps (1) to (3):
(1) a step of preparing a fermented milk mix using milk raw materials,
(2) A method for producing fermented milk, comprising a step of heat-sterilizing a fermented milk mix, and (3) a step of adding a starter to the heat-sterilized fermented milk mix and fermenting the mixture.
In the steps (1) to (3), the following (A) to (C):
(A) In the step (1), a process of adding glucose oxidase to a fermented milk mix having a glucose concentration of 0.05% by weight or less to prepare a fermented milk mix under the conditions of the glucose concentration,
(B) a process of adding glucose oxidase to a fermented milk mix having a heat-sterilized glucose concentration of 0.05% by weight or less before the step (3);
(C) A process of adding glucose oxidase to fermented milk having a glucose concentration of 0.05% by weight or less prepared in the step (3) after the step (3).
A manufacturing method characterized in that at least one of the processes is performed.

  In the present invention, “fermented milk” means “fermented with lactic acid bacteria or yeast containing milk or a non-fat milk solid content equal to or higher than milk, as defined in the ordinance of milk, etc. Yogurt (non-fat milk solid content of 8% or more and containing 10 million or more lactic acid bacteria or yeast per ml: Ministry of Health, Labor and Welfare ordinance of Japan), milk Product lactic acid bacteria beverage (non-fat milk solid content is less than 8% and contains 10 million or more lactic acid bacteria or yeast per ml: Japan Ministry of Health, Labor and Welfare Ordinance) and lactic acid bacteria beverage (non-fat milk solid content is 3 %, Which contains 10 million or more lactic acid bacteria or yeast per ml: Ministry of Health, Labor and Welfare of Japan), preferably yogurt.

  Yogurt is classified into two types, “pre-fermentation type” and “post-fermentation type”, depending on the preparation method. The former pre-fermentation type yogurt is fermented in a tank with a fermentation mix prepared by adding a fermented milk starter to raw milk, and then the generated card is crushed and, if necessary, with a gelling agent. Manufactured by filling food containers. On the other hand, the latter post-fermentation type yogurt is manufactured by adding a fermented milk starter to raw material milk to prepare a fermented mix, filling the fermented mix into a single-meal container, and fermenting in the container. Generally, soft yogurt and drink yogurt belong to the “pre-fermentation type”, and hard yogurt belongs to the “post-fermentation type”.

  The yogurt targeted by the present invention includes these two types of yogurt: “pre-fermentation type” and “post-fermentation type”. In the case of the “post-fermentation type” produced by fermenting in a single food container, glucose oxidase or the like cannot be added to the fermented milk after the operation of (C), that is, the fermentation step of (3). For this reason, when producing a “post-fermentation type” yogurt, the production method of the present invention performs the operation of (A) in the above step (1) or (3) before the step (B). Performed by operation. However, in the “pre-fermentation type” manufactured by filling a single-meal container after fermentation, there is no such limitation, and the operation (A) is performed in the step (1) or the step (3) (B) or (C) is performed after step (3), or at least one of the operations can be performed.

  The fermented milk targeted by the present invention is preferably a “pre-fermented type” yogurt characterized by a smoother texture, and the production method of the present invention comprises the “pre-fermented type” yogurt (soft yogurt And drink yogurt).

Hereinafter, the production steps (1) to (3) of the present invention will be described in order:
(1) Process of preparing fermented milk mix using dairy ingredients “dairy ingredients” means dairy products used as raw materials for fermented milk, such as raw milk (unsterilized milk), sterilized milk (sterilized) Milk), nonfat milk, full fat concentrated milk, nonfat concentrated milk, full fat milk powder, skim milk powder, butter (unsalted butter), buttermilk, cream, whey protein concentrate (WPC), whey protein isolate (WPI) , Α-lactalbumin (α-La), β-lactoglobulin (β-Lg), etc., can be appropriately selected according to the type of fermented milk actually produced. These can be used in combination of two or more. For example, in the case of yogurt, raw milk and / or pasteurized milk (in order to achieve a non-fat milk solid content of 8% or more with low energy) ( Non-fat milk and / or non-fat dry milk can be combined with (sterilized milk). At this time, it is preferable to use raw milk (unsterilized milk) and a processed product thereof as a milk raw material from the viewpoint of good flavor and the like.

  Since the glucose concentration contained in the fermented milk mix depends on the glucose concentration of each milk raw material, it may be a total value thereof and is not particularly limited. However, in the case of yogurt, for example, in 100% by weight of the fermented milk mix, glucose is 0 to 0.05% by weight, preferably 0.003 to 0.04% by weight, more preferably 0.005 to 0.03% by weight, More preferably, the milk raw materials described above can be used in appropriate combination within the range of 0.007 to 0.02% by weight.

  “Fermented milk mix” is a raw material preparation in which fermented milk ingredients are mixed. If necessary, sugars such as water and sugar (provided that the substrate of glucose oxidase [glucose] And a sweetening agent such as a sweetener and a flavoring agent are added (blended), and if necessary, dissolved and heated. If necessary, stabilizers (gelling agents) such as gelatin, agar, carrageenan, guar gum, low methoxy pectin and high methoxy pectin can be added.

  However, the present invention is characterized in that a glucose oxidase substrate and a substance that can be a glucose oxidase substrate are preferably not used as raw materials other than milk raw materials. That is, in the present invention, the glucose oxidase substrate and / or the substance that can be the glucose oxidase substrate contained in the fermented milk mix are preferably all derived from milk raw materials. Here, the substrate of glucose oxidase is glucose. The “substance that can be a substrate for glucose oxidase” means a substance that produces a substrate for glucose oxidase (glucose). Although what produces | generates glucose in particular is not restrict | limited, What produces | generates glucose using milk ingredient or the component contained in milk ingredient as a substrate can be illustrated, Specifically, glucose is produced using lactose as a substrate. Mention may be made of glucose-producing enzymes such as lactase.

  The ratio of each raw material to be added to the fermented milk mix is determined according to the type of fermented milk (non-fat milk solid content) (yogurt: 8% or more, dairy lactic acid bacteria beverage: less than 8%, lactic acid bacteria beverage: 3 %), And as long as it is satisfied, there is no particular limitation. However, in the case of yogurt, for example, the fat content is 0 to 8% by weight, preferably 0.1 to 6% by weight, more preferably 0.5 to 4% by weight in 100% by weight of the fermented milk mix. The milk raw materials described above can be used in appropriate combination within the range where the non-fat milk solid content is 5 to 25% by weight, preferably 6 to 20% by weight, more preferably 7 to 15% by weight. In addition, since what fermented fermented milk mix is fermented milk made into the object of this invention, said "fermented milk mix in 100 weight%" can be paraphrased with "fermented milk in 100 weight%." .

  The milk raw materials can be appropriately combined so that the fat content and the non-fat milk solid content are within the above ranges. For example, when raw milk (and / or pasteurized milk) and skim milk powder are used as the milk raw material, raw milk (And / or pasteurized milk, etc.) 0 to 100% by weight, preferably 10 to 90% by weight, more preferably 20 to 80% by weight, still more preferably 40 to 80% by weight; 0 to 25% by weight, preferably 1 to 20% by weight, more preferably 2 to 15% by weight, and still more preferably 2 to 10% by weight.

  The production method for carrying out the treatment (A) in the step (1) which is an embodiment of the present invention is characterized in that glucose oxidase is used as one of the raw materials in the preparation of the fermented milk mix. The production method for carrying out the treatment (A) in the step (1) is a preferred embodiment of the present invention because the reaction time of glucose oxidase is easy to adjust.

  In addition, when fermented milk mix is heated and prepared, if glucose oxidase is added to this, there exists a possibility that an enzyme may be deactivated. For this reason, when glucose oxidase is added, the fermented milk mix prepared by heat sterilization is cooled to a temperature at which the enzyme is not previously deactivated, preferably to room temperature (25 ± 5 ° C.) or less, more preferably to 15 ° C. or less. It is preferable to keep it.

  A commercially available glucose oxidase preparation can be used for glucose oxidase. Examples of commercially available glucose oxidase preparations include, for example, Shin Nippon Chemical Industry Co., Ltd., DKSH Japan Co., Ltd., Shonan Wako Pure Chemical Industries, Ltd., Nagase Seikagaku Corporation, Kyowa Enzyme Co., Ltd. ) (All of which are from Japan) and the like. However, it is not limited to these.

  The blending ratio of glucose oxidase (about 2000 to 4000 units / kg) per 100% by weight of the fermented milk mix is 0.1 to 1% by weight, preferably 0.1 to 0.5% by weight, more preferably 0.15 to 5%. 0.3 weight%, More preferably, 0.15-0.2 weight% can be mentioned.

  Thus, the fermented milk mix to which glucose oxidase is added (blended) has a temperature of 5 to 43 ° C, preferably 5 to 35 ° C, more preferably 5 to 30 ° C, and still more preferably 5 to 25 ° C. Placed. The standing time is not particularly limited, but is usually 1.5 hours or more, preferably 1.5 to 24 hours, more preferably 2 to 16 hours, further preferably 2 to 6 hours, and particularly preferably 2 to 4 hours. It's time.

(2) Process of heat-sterilizing fermented milk mix
Fermented milk mix prepared in the step (1) (Note that this fermented milk mix includes both those prepared through the operation (A) and those prepared through the operation (A). ) Is then subjected to a sterilization treatment by heating.

  The heating temperature and the heating time are not particularly limited as long as the target sterilization can be performed. For this reason, unlike the method of patent document 9, the heating temperature of 65 degreeC or more is employ | adopted. Preferably, it is sufficient that the temperature of the fermented milk mix itself is 90 ° C. or higher, preferably 90 to 100 ° C., more preferably about 95 ° C., for example, the fermented milk mix is 1 at 90 to 100 ° C. A method of treating in ˜5 minutes, a method of treating in 90 to 95 ° C. for 1 to 3 minutes, and the like can be mentioned without limitation.

  In another embodiment of the present invention, the production method (B) is performed before (3) step, and glucose oxidase is added (blended) to the fermented milk mix heat-sterilized by the above method in (2) step. It is characterized by that.

  The target fermented milk mix here is preferably prepared in the step (1) without undergoing the operation (A). After this fermented milk mix is heat-sterilized, glucose oxidase is added (mixed). In this case, if glucose oxidase is added while the fermented milk mix is at a high temperature, the enzyme may be deactivated. For this reason, when adding glucose oxidase, the fermented milk mix is previously set to 5 to 43 ° C., preferably 5 to 35 ° C., more preferably 5 to 30 ° C., and more preferably 5 to 35 ° C. It is preferable to cool to 25 ° C.

  The amount of glucose oxidase used and its source are as described above.

(3) Adding fermented milk starter to the heat-sterilized fermented milk mix and fermenting
Fermented milk mix heat-sterilized in the process of (2) (Note that this mix is prepared through the operation (A), (B) prepared through the operation, (A) and (B) Those prepared without any operation are then subjected to a fermentation treatment.

  “Starter” means an inoculum such as lactic acid bacteria or yeast inoculated to ferment a fermented milk mix. In the present invention, a known starter can be appropriately used as the “starter”, but a lactic acid bacteria starter is preferable. Lactobacillus starters include L. bulgaricus, L. bulgaricus, S. thermophilus, Streptococcus makedonisu, L. lactis, L. lactis, Lactobacillus gasseri (L. gasseri) In addition to Lactobacillus acidophilus and Bifidobacterium, one or more lactic acid bacteria generally used for producing fermented milk can be used. Among them, a lactic acid bacteria starter based on a mixed starter of Lactobacillus bulgaricus (L.bulgaricus) and Streptococcus thermophilus (S. it can. Based on this lactic acid bacteria starter, after considering the fermentation temperature and fermentation conditions of the desired fermented milk, add other lactic acid bacteria such as Lactobacillus gasseri and Bifidobacterium Also good.

  The addition amount of a starter can be suitably set according to the addition amount employ | adopted in the manufacturing method of well-known fermented milk. In addition, the starter inoculation method is not particularly limited, and a method commonly used in the production of fermented milk can be appropriately used.

  The conditions for the fermentation treatment can be appropriately set in consideration of the type of fermented milk, the desired flavor, the type of starter to be used, and the like. For example, the temperature (fermentation temperature) in a fermentation chamber is maintained in the range of 30-50 degreeC, and the method of making it ferment while leaving still in the fermentation chamber can be mentioned. If it is such temperature conditions, since lactic acid bacteria generally tend to be active, fermentation can proceed effectively. The fermentation temperature is usually about 30 to 50 ° C, preferably 35 to 45 ° C, more preferably 37 to 43 ° C.

  The fermentation time can be appropriately set and adjusted with reference to the fact that the lactic acid acidity of the fermented milk mix reaches a predetermined ratio. The lactic acid acidity is, for example, about 0.7 to 1.5% in the case of “pre-fermentation type” yogurt, and about 0.7 to 0.8% in the case of “post-fermentation type” yogurt. The fermentation time is usually about 1 hour to 12 hours, preferably about 2 hours to 5 hours, more preferably about 3 hours to 4 hours.

  In the case of “pre-fermentation type” yogurt, when the lactic acid acidity reaches about 1.5 to 2%, and in the case of “post-fermentation type” yogurt, when the lactic acid acidity reaches about 0.7 to 0.8%, For example, it cools to 15 degrees C or less, Preferably it is 0-10 degreeC, More preferably, it is 3-7 degreeC, and fermentation is stopped.

  In the case of a “pre-fermentation type” yogurt, the operation (C) can be performed after the step (3). That is, glucose oxidase can be added (blended) to the fermented milk prepared by the steps (1) to (3).

  Thus, the fermented milk to which glucose oxidase is added (blended) has a temperature of 5 to 43 ° C, preferably 5 to 35 ° C, more preferably 5 to 30 ° C, and still more preferably 5 to 25 ° C. Placed. The standing time is not particularly limited, but is usually 1.5 hours or more, preferably 1.5 to 24 hours, more preferably 2 to 16 hours, further preferably 2 to 6 hours, and particularly preferably 2 to 4 hours. It's time.

  The manufacturing method containing the said (C) operation is one aspect | mode of the manufacturing method of this invention. The fermented milk targeted here is preferably a “pre-fermented type” yogurt as described above, and (1) the process is not subjected to (A), and (3) before the process. (B) It was prepared without operation.

  Here, the amount of glucose oxidase used and its source are as described above.

  Through the steps (1) to (3) described above, fermented milk targeted by the present invention can be produced. When the fermented milk is a “pre-fermentation type” yogurt, the culture step (3) is performed using a tank (tank culture). Moreover, when (C) operation is performed after the said (3) process, the said (C) operation is also performed with respect to fermented milk prepared in the tank. After tank culture, fermented and coagulated curd is agitated and crushed and, if necessary, sterilized, cooled, emulsified, and aged, then filled into a single-meal container and prepared as a fermented milk product. .

  In addition, when the “pre-fermentation type” yogurt is produced using the production method of the present invention, even if the solid content of the fermented milk mix is high, the hardness of the curd obtained after fermentation in the tank is 35 to 55 g, preferably It is relatively soft, 35-50 g, more preferably 35-45 g. Therefore, the card is not crushed by a conventional homogenization method, but can be easily crushed by passing it through a filter (membrane) having a pore size of about 60 mesh, and a smooth textured yogurt can be prepared.

  On the other hand, when the fermented milk is a “post-fermentation type” yoghurt, the fermented milk mix is filled in the individual food container before the culture process of (3), and the culture process of (3) is performed in the container. Performed (in-vessel culture). For this reason, as described above, in the case of the “post-fermentation type”, the operation (C) is not performed in the culture step (3). After culturing in the container, it is cooled (refrigerated) and prepared as a product of fermented milk.

II. Method for improving physical properties of fermented milk The method for improving physical properties of fermented milk of the present invention includes at least the following three steps (1) to (3):
(1) a step of preparing a fermented milk mix using milk raw materials,
Changes in physical properties associated with milk protein aggregation in fermented milk products produced by a method comprising (2) heat-sterilizing the fermented milk mix and (3) adding a starter to the heat-sterilized fermented milk mix and fermenting A method of suppressing
In the steps (1) to (3), at least one of the following (A) to (C) is performed:
(A) In the step (1), a process of adding glucose oxidase to a fermented milk mix having a glucose concentration of 0.05% by weight or less to prepare a fermented milk mix under the conditions of the glucose concentration,
(B) a process of adding glucose oxidase to a fermented milk mix having a heat-sterilized glucose concentration of 0.05% by weight or less before the step (3);
(C) The process which adds glucose oxidase to fermented milk whose glucose concentration prepared by the (3) process is 0.05 weight% or less after the (3) process.

  In the method of the present invention described above, the treatments and conditions performed in each step and each operation, and the materials used in each step and each operation are all described in “I. Method for Producing Fermented Milk with Improved Physical Properties”. Things can be used as well.

  The fermented milk manufactured or processed in this manner is manufactured without using any of the operations (A) to (C) as shown in the examples described later, that is, without using glucose oxidase. Compared to fermented milk produced and / or fermented milk produced using glucose oxidase at a glucose concentration of 1% by weight or more (hereinafter collectively referred to as “control fermented milk”). Changes in physical properties associated with are significantly suppressed. Here, the physical property change accompanying the aggregation of the milk protein can include at least one selected from the generation of water separation, the increase in the particle diameter of the milk protein (aggregated particles), and the generation of roughness of the tissue of the fermented milk. . The texture of the fermented milk tissue is not particularly restricted, but is considered to be a phenomenon caused by an increase in the milk protein particle size.

  Regarding the occurrence of water separation among the above physical property changes, it is preferable that water separation does not occur during the storage period of 16 days from production (water separation rate 0%), or even if it occurs, the water separation rate is preferably 19% or less. More preferably, the water separation rate is 15% or less, and particularly preferably 10% or less. In addition, a water separation rate can be calculated | required as a ratio of the weight of the supernatant produced by water separation with respect to the weight (100 weight%) of all fermented milk. In addition, the increase rate of the average particle diameter of milk protein (aggregated particles) during the storage period of 16 days from the production is preferably 30% or less. More preferably, it is 25% or less. The increase rate of the average particle size is the ratio of the average particle size (L0) immediately after production to the difference (Lt-L0) between the average particle size (Lt) after storage for 16 days and the average particle size (Lo) immediately after production ({ [Lt−L0] / L0} × 100). In this case, the average particle size of the milk protein (aggregated particles) after 16 days of storage is preferably 13 μm or less. Furthermore, it is preferable that the fluctuation rate of the hardness and the viscosity in the storage period of 16 days from the production is 20% or less and 30% or less, respectively. In addition, although these numerical ranges become a standard of the suitable aspect of this invention, this invention is not restrained.

  The physical properties change over time even when any fermented milk is stored under the refrigerated conditions, but the fermented milk of the present invention has a change over time (physical properties) compared to the fermented milk of the control. (Change) is significantly suppressed. For this reason, the method of the present invention is useful for maintaining the quality (appearance and texture) of fermented milk in a good state for as long as possible, at least during the expiration date. Considering the shelf life of yogurt, the period for maintaining the quality of fermented milk in a good state is about 7 days from the first day of production, preferably about 10 days, more preferably about 12 days, and more preferably about 14 days. be able to.

  Hereinafter, the present invention will be specifically described using experimental examples and examples. However, the present invention is not limited to these, and various improvements can be made based on known methods.

Experimental Example 1: Effect of improving physical properties of fermented milk having a general composition
(1) Preparation of fermented milk 1-3 According to the prescription described in Table 1, three types of fermented milk 1-3 were prepared.
In Table 1, “fermented milk 1” is fermented milk (Comparative Example 1) having a conventionally known formulation (conventional formulation) (glucose concentration: about 0.015 wt%). “Fermented milk 2” is fermented milk (Example 1) prepared by adding glucose oxidase to the conventional formulation of “fermented milk 1” (glucose concentration: about 0.015% by weight). ). “Fermented milk 3” is fermented milk (Comparative Example 2) prepared by adding lactase to the formulation of “fermented milk 2”. By adding lactase, lactose (lactose concentration: about 6% by weight) contained in raw milk or skim milk is hydrolyzed, and glucose is generated in the raw material. In addition, the glucose concentration of fermented milk 3 (Comparative Example 2) is a theoretical value of 3.07% by weight assuming that lactose is completely decomposed by lactase.

  Specifically, for each of the fermented milks 1 to 3, the milk materials shown in Table 1 (raw milk, skim milk powder, unsalted butter, WPC34 (whey protein concentrate)) (fat content: 3.1 wt%, no Fat milk solid content: 10.8% by weight) and raw water were placed in a small tank and dissolved by stirring and mixing while heating at about 60 ° C. to prepare each raw milk (fermented milk mix). Then, after cooling each raw material milk to about 5 ° C., glucose oxidase was added for fermented milk 2 and lactase and glucose oxidase were added for fermented milk 3 according to the formulation shown in Table 1 ((1) Process).

  Next, each raw material milk (fermented milk mix) prepared above was allowed to stand at about 5 ° C. for about 14 hours, and then heat sterilized with stirring until it reached about 95 ° C. (step (2)). Each sterilized milk thus prepared was cooled to about 43 ° C. and then inoculated (added) with a lactic acid bacteria starter at a rate of 2% by weight (step (3)).

  Thereafter, each sterilized milk to which a lactic acid bacteria starter was added was filled into a small container, left in a fermentation chamber at about 43 ° C., and transferred to a refrigerator at about 5 ° C. when the lactic acid acidity reached 0.72%. By leaving still with the said refrigerator, fermentation was stopped and each fermented milk 1-3 was prepared.

(2) Evaluation of physical properties of fermented milk 1-3 After fermented milk 1-3 prepared as described above is allowed to stand at about 5 ° C. for 16 days, water separation rate [%], coagulated particles mixed in fermented milk Average particle diameter [μm], lactic acid acidity [%], pH (20 ° C), hardness (card tension, CT) [g], viscosity [Pa · s] over time (first day of production (first day), production) Measurements were made on the 8th and 16th days later).

        Each item was measured according to the following method.

(A) Measurement of water separation rate of fermented milk 40 g of fermented milk (10 ° C) was filled into a centrifugal sedimentation tube (inner diameter: 20 mm) and used for a centrifuge (centrifugal force: about 180 G (rotating radius: 160 mm, rotation speed: 1000 rpm, treatment time: 10 minutes) Next, the weight of the supernatant was measured, and the ratio of the weight of the supernatant to the total weight (40 g) of the fermented milk was determined as the water separation rate [%]. Calculated.

(B) Measurement of average particle size of coagulated particles mixed in fermented milk Using laser diffraction particle size distribution analyzer SALD-2000 (Shimadzu Corporation), the average particle size [μm] of coagulated particles mixed in fermented milk was measured. .

(C) Measurement of lactic acidity (acidity) of fermented milk After adding phenolphthalein as an indicator to fermented milk, sodium hydroxide (0.1 N) was added as a titrant to fermented milk and measured. Specifically, the amount of lactic acid (concentration) contained in the fermented milk is converted from the amount of sodium hydroxide added when the fermented milk turns pale pink, and the numerical value is used as an index.

(D) Measurement of Fermented Milk Hardness (Card Tension, CT) Hardness [g] of fermented milk was measured using Neo Card Meter M302 (I Techno Engineering: former Iio Electric). In this hardness meter, for example, 100 g of fermented milk (10 ° C) is filled into a small container, and a yogurt knife (small disk shape, diameter: about 20 mm) is inserted to evaluate the hardness and smoothness of the fermented milk. it can. Specifically, the invasion angle of fermented milk is measured with a yoghurt knife with a 100 g weight, and the measured value is expressed by a curve. At this time, the height of the knife is on the vertical axis, and the weight added to 100 g is the horizontal axis. Then, 10 mm on the vertical axis and 10 g on the horizontal axis are the same distance. The distance to the break of the penetration angle curve is used as an index of hardness (hardness, elasticity) (g).

(E) Measurement of viscosity of fermented milk The viscosity [Pa · s] of fermented milk was measured using a rotary B-type viscometer TV-10M (Toki Sangyo). Specifically, 100 g of fermented milk (10 ° C.) is filled in a small container, and rotor No. 4 (code M23) of the above viscometer is inserted into this fermented milk and rotated (30 rpm, 30 seconds). The viscosity is evaluated.

  Table 2 shows the measurement results of the physical properties of fermented milk 1 to 3 (three types).

[About water separation rate]
“Fermented milk 2 (Example 1)” has a smaller variation rate of water separation than “Fermented milk 1 (Comparative example 1)” and “Fermented milk 3 (Comparative example 2)”, and it has continued for 16 days from the first day of production. Thus, it was confirmed that the occurrence of water separation was stably suppressed. In other words, compared to “fermented milk 1” and “fermented milk 3”, in “fermented milk 2”, water separation is stably suppressed over time during refrigerated storage and distribution, and the physical properties are good. It is thought that it will be maintained.

[Average particle size]
“Fermented milk 2 (Example 1)” has a smaller change in average particle size compared to “Fermented milk 1 (Comparative example 1)” and “Fermented milk 3 (Comparative example 2)”, and 16 days from the first day of production. In particular, it was confirmed that the average particle size was stably maintained over the period from the first day of production to 8 days. In other words, compared to “fermented milk 1” and “fermented milk 3”, in “fermented milk 2”, the average particle size is less likely to change over time during refrigerated storage and distribution, and good physical properties are maintained. It is thought.

[About hardness]
The hardness of “fermented milk 1 (Comparative Example 1)” increases somewhat over time from the first day of production, and the hardness of “fermented milk 2 (Example 1)” and “fermented milk 3 (Comparative Example 2)” There was a tendency to decrease somewhat over time from the first day, but the hardness of any fermented milk as a whole did not change significantly over time, and Example 1 showed the smallest change over time.

[Viscosity]
The viscosity of any fermented milk of “fermented milk 1 (Comparative Example 1)”, “fermented milk 2 (Example 1)” and “fermented milk 3 (Comparative Example 2)” tends to decrease over time from the first day of production. Was recognized. However, the degree of the decrease is greatest for “fermented milk 1 (comparative example 1)” and then the largest for “fermented milk 3 (comparative example 2)”. It was confirmed that the actual decrease was significantly suppressed compared to “fermented milk 1” and “fermented milk 3”. Therefore, compared with “fermented milk 1” and “fermented milk 3”, the viscosity of “fermented milk 2” is less likely to change over time during refrigerated storage and distribution, and good physical properties are maintained. It is thought.

[Acidity and pH]
The lactic acid acidity and pH of “fermented milk 1 (Comparative Example 1)”, “fermented milk 2 (Example 1)” and “fermented milk 3 (Comparative Example 2)” were almost the same. That is, it is considered that the flavor (sourness) of each fermented milk hardly changes with time during refrigerated storage or distribution, and the good flavor is maintained.

(3) Flavor Evaluation of Fermented Milk 1-3 For the fermented milk 1-3 prepared in (1) above, a sensory test (flavor evaluation) was performed by five specialist panels. Table 3 shows the inspection results (evaluation results).

  As shown in Table 3, compared with “fermented milk 1 (Comparative Example 1)”, “fermented milk 2 (Example 1)” and “fermented milk 3 (Comparative Example 2)” have smooth texture and yarn. The pullability was felt strongly. In addition, the smoothness and stringiness were stably maintained for 16 days from the first day of manufacture. Therefore, compared to “fermented milk 1”, the texture of “fermented milk 2” and “fermented milk 3” is less likely to change over time during refrigerated storage and distribution, and the texture (smoothness and yarn) (Pullability) is considered to be maintained well.

Experimental Example 2: Effect of improving physical properties of fermented milk having a high composition
(1) Preparation of fermented milk 4-5 According to the prescription described in Table 4, two types of fermented milk 4-5 were prepared.
In Table 4, “fermented milk 4” is high-fat fermented milk (Comparative Example 3) having a conventionally known formulation (conventional formulation) (glucose concentration: about 0.01% by weight). “Fermented milk 5” is fermented milk (Example 2) prepared by adding glucose oxidase to the conventional formulation of “fermented milk 4” (glucose concentration: about 0.01% by weight). ).

  Specifically, the milk raw materials (fat dry milk, cream, WPC34 (whey protein concentrate), MPC (milk protein concentrate)) shown in Table 4 (fat content: 8.0% by weight, nonfat milk solid content: 14.6% by weight) and raw material water were added to a small tank and dissolved by stirring and mixing while keeping the temperature at about 60 ° C. to prepare each raw milk (fermented milk mix). Then, after each raw material milk was cooled to about 5 ° C., glucose oxidase was added to fermented milk 5 according to the formulation shown in Table 4 (step (1)).

  Next, each raw material milk prepared above was allowed to stand at about 5 ° C. for about 16 hours, and then heat sterilized with stirring until it reached about 95 ° C. (step (2)). Each sterilized milk thus prepared was cooled to about 43 ° C. and then inoculated (added) with a lactic acid bacteria starter at a ratio of 2% by weight (step (3)).

  Thereafter, each sterilized milk to which a lactic acid bacteria starter was added was filled in a small tank, left at about 43 ° C., and filtered (backed) using a filter (60 mesh) when the pH reached 4.6. Next, it was filled into a small container, cooled to 10 ° C. or lower with ice water to stop fermentation, and each fermented milk 4 and 5 was prepared.

(2) Evaluation of physical properties of fermented milks 4 to 5 Further, after leaving these fermented milks 4 to 5 to stand at about 5 ° C. for 2 days, the average particle size [μm], lactic acid was measured according to the method described in Experimental Example 1. The acidity [%], pH (20 ° C.), and viscosity [Pa · s] were measured.

  Table 5 shows the measurement results.

  As shown in Table 5, compared to “fermented milk 4 (Comparative Example 3)”, “fermented milk 5 (Example 2)” had almost the same acidity, pH and viscosity. The average particle size was much smaller. From this, even fermented milk with a high fat content and fermented milk with a high solid content concentration can be produced by adding glucose oxidase in the same manner as “fermented milk 2 (Example 1)” in Experimental Example 1. It can be seen that fermented milk having a small average particle size and small change with time and good physical properties can be obtained.

(3) Flavor evaluation of fermented milk 4-5 Sensory inspection (flavor evaluation) was conducted on five fermented panels for fermented milk 4-5. The test results (evaluation results) are shown in Table 6.

  As shown in Table 6, “fermented milk 4 (Comparative Example 3)” has a rough feeling, whereas “fermented milk 5 (Example 2)” has a smooth texture and texture. confirmed. In addition, “fermented milk 5 (Example 2)” had a rich texture due to a combination of a sense of fat and an appropriate stickiness (stringiness).

Claims (16)

(1) a step of preparing a fermented milk mix using milk raw materials,
(2) A method for producing fermented milk, comprising a step of heat-sterilizing a fermented milk mix, and (3) a step of adding a starter to the heat-sterilized fermented milk mix and fermenting the mixture.
In the above steps (1) to (3), the following process (A) or (B) is performed:
(A) In the step (1), a process of adding glucose oxidase to a fermented milk mix having a glucose concentration of 0.003 to 0.05 % by weight to prepare a fermented milk mix under the conditions of the glucose concentration,
(B) (3) before step, processing the heat-sterilized glucose concentration is added to the glucose oxidase in the fermented milk mix 0.003 to 0.05 wt%. The process according to claim 1, wherein the process (A) is performed in the step (1), and the heat sterilization temperature in the step (2) is 65 ° C or higher. The production method according to claim 1 or 2, wherein a Bulgarian bacterium (Lactobacillus bulg aricus) and a thermophilus bacterium (Streptococcus thermophilus) are used in combination as a starter. Compared with fermented milk produced without using glucose oxidase and / or fermented milk produced with glucose oxidase at a glucose concentration of 1% by weight or more, changes in physical properties associated with milk protein aggregation are suppressed. The manufacturing method in any one of Claims 1 thru | or 3 which is a manufacturing method of dried fermented milk.   5. The physical property change accompanying aggregation of milk protein is at least one selected from the group consisting of generation of water separation, increase in particle diameter of milk protein and / or fat, and generation of roughness of tissue of fermented milk. Manufacturing method.   6. The production method according to claim 1, wherein unsterilized milk is used as a milk raw material.   The production method according to any one of claims 1 to 6, wherein the fermented milk is yogurt. (1) a step of preparing a fermented milk mix using milk raw materials,
(2) Changes in physical properties associated with aggregation of milk proteins in fermented milk produced by a method comprising a step of heat-sterilizing a fermented milk mix, and (3) adding a starter to the heat-sterilized fermented milk mix and fermenting the fermented milk mix A method of suppressing
In the above steps (1) to (3), the following method (A) or (B) is performed:
(A) In the step (1), a process of adding glucose oxidase to a fermented milk mix having a glucose concentration of 0.003 to 0.05 % by weight to prepare a fermented milk mix under the conditions of the glucose concentration,
(B) (3) before step, processing the heat-sterilized glucose concentration is added to the glucose oxidase in the fermented milk mix 0.003 to 0.05 wt%. The method according to claim 8, wherein the treatment (A) is performed in the step (1), and the heat sterilization temperature in the step (2) is 65 ° C or higher. The method according to claim 8 or 9, wherein a Bulgarian bacterium (Lactobacillus bulg aricus) and a thermophilus bacterium (Streptococcus thermophilus) are used in combination as a starter.   Compared with fermented milk produced without using glucose oxidase and / or fermented milk produced with glucose oxidase at a glucose concentration of 1% by weight or more, changes in physical properties associated with milk protein aggregation are suppressed. The method according to claim 8, which is a method.   The physical property change accompanying the aggregation of milk protein is at least one selected from the group consisting of water separation, increase in milk protein and / or fat particle size, and generation of graininess in fermented milk tissue. 11. The method according to any one of 11.   The method according to any one of claims 8 to 12, wherein unsterilized milk is used as a milk raw material.   The method according to any one of claims 8 to 13, wherein the fermented milk is yogurt.   The method according to any one of claims 1 to 7, wherein the method does not include an operation of externally adding a substrate for glucose oxidase and a substance that can be a substrate for glucose oxidase as components other than milk raw materials throughout all steps (1) to (3). The manufacturing method described in any one.   The method according to any one of claims 8 to 13, which does not include an operation of externally adding a substrate for glucose oxidase and a substance that can be a substrate for glucose oxidase as components other than milk raw materials throughout all steps (1) to (3) The method described in any one.