JP6850570B2 - Milk protein concentrates and methods of their production, methods of reducing the saltiness and "egumi" of dairy products without compromising the milk flavor of dairy products and dairy products. - Google Patents

Description

The present invention relates to a milk protein concentrate and a method for producing the same. The present invention also relates to a dairy product using the milk protein. Furthermore, the present invention also relates to a method of reducing the saltiness and "egumi" of a dairy product without impairing the milky flavor of the dairy product.

In the past, it has been proposed that "skimmed milk is decalcified using a cation exchange resin to produce a milk protein concentrate" (for example, JP-A-2010-502182, JP2011-024589). See publications, etc.). Such milk protein concentrates have high thermal stability and are used as useful raw materials for various dairy products such as formula milk powder, beverages, fermented milk, and ice cream.

Special Table 2010-502182 Japanese Unexamined Patent Publication No. 2011-024589

However, when a dairy product is prepared using the milk protein concentrate obtained as described above, the salty taste and "egumi" of the dairy product are weakened, but the milk flavor tends to be insufficient.

An object of the present invention is to provide a milk protein concentrate and a method for producing the same, which do not impair the milk flavor while ensuring thermal stability.

The method for producing a milk protein concentrate (also referred to as “Milk Protein Concentrate” (hereinafter abbreviated as “MPC”)) according to the first aspect of the present invention is 130 in the range of pH 6.45 or more and 6.75 or less. A method for producing a milk protein concentrate having a heat coagulation time at ° C. of 4 minutes or more, which comprises a pH adjusting step, a first milk protein concentrate preparation step, and a pH readjustment step. In the pH adjusting step, the pH of the skim milk is adjusted within the range of 5.5 or more and less than 6.5 to prepare the pH adjusted skim milk. In the first milk protein concentrate preparation step, the pH-adjusted skim milk is ultrafiltered to prepare the first milk protein concentrate. Before proceeding from the pH adjusting step to the first milk protein concentrate preparation step, it is preferable to allow the pH-adjusted skim milk to stand or stir for a predetermined time. This is to sufficiently dissociate (free) ions such as calcium from proteins (that is, casein and the like). In the pH readjustment step, the pH of the first milk protein concentrate is adjusted within the range of 6.45 or more and 6.75 or less to prepare the second milk protein concentrate.

In this method for producing a milk protein concentrate, the pH of skim milk is adjusted within the range of 5.5 or more and less than 6.5, and then the raw material (that is, pH-adjusted skim milk) is subjected to ultrafiltration treatment. Here, in the pH-adjusted defatted milk, calcium ions, magnesium ions, etc. that are electrostatically bound to the protein are partially dissociated (usually, the pH of the pH-adjusted defatted milk is 5.2. Below, all calcium ions, magnesium ions, etc. are dissociated.) Then, the partially dissociated calcium ions, magnesium ions, etc. are discharged together with the water content of the permeate when the pH-adjusted skim milk is subjected to ultrafiltration treatment. As a result, a milk protein concentrate in which calcium ions, magnesium ions, etc. remain in an appropriate amount is prepared. Therefore, the thermal stability of this milk protein concentrate is enhanced, and the milk flavor is not impaired in the dairy products produced using the milk protein concentrate. Further, in this method for producing a milk protein concentrate, no ion exchange treatment is performed. Therefore, in the overall flow of the method for producing the milk protein concentrate, the work man-hours can be reduced and the production cost can be kept low. Further, in this method for producing a milk protein concentrate, the pH readjustment step is performed, so that the acidity of the first milk protein concentrate can be suppressed. Further, in the pH readjustment step, the quantitative balance of sodium ions and potassium ions in the first milk protein concentrate can be adjusted by using sodium hydroxide and potassium hydroxide. In addition, as described above, the milk protein concentrate produced by this production method has excellent thermal stability. Therefore, when producing a dairy product or the like using this milk protein concentrate as a raw material, operations in the heat sterilization step and the like are performed. No need to complicate. Therefore, the milk protein concentrate produced by this production method can keep the production cost of dairy products and the like low in some cases.

The method for producing a milk protein concentrate according to the second aspect of the present invention is the method for producing a milk protein concentrate according to the first aspect, and in the pH adjusting step, the pH of skim milk is 5.5 or more and 5.8. The pH-adjusted skim milk is prepared within the following range.

The method for producing a milk protein concentrate according to the third aspect of the present invention is the method for producing a milk protein concentrate according to the first or second phase, and in the pH readjustment step, sodium hydroxide and potassium hydroxide are produced. The pH of the first milk protein concentrate is adjusted within the range of 6.45 or more and 6.75 or less by adding the mixed aqueous solution of the first milk protein concentrate to the first milk protein concentrate, and the second milk protein concentrate is prepared. To.

The method for producing a milk protein concentrate according to the fourth aspect of the present invention is a method for producing a milk protein concentrate according to any one of the first to third aspects, and the second milk protein concentrate is a method for producing the milk protein concentrate. It is liquid.

The method for producing a milk protein concentrate according to the fifth aspect of the present invention is a method for producing a milk protein concentrate according to any one of the first to fourth aspects, and the second milk protein concentrate is a method for producing the milk protein concentrate. The protein content is in the range of 9.0% by mass or more and 15.5% by mass or less, and the ash content is 0.40% by mass or more and 1.55% by mass or less per 20% by mass of the total solid content. It is within the range, the sodium content is within the range of 0.01% by mass or more and 0.10% by mass or less, and the potassium content is within the range of 0.05% by mass or more and 0.40% by mass or less. , The calcium content is in the range of 0.15% by mass or more and 0.40% by mass or less, the magnesium content is in the range of more than 0.00% by mass and 0.03% by mass or less, and the phosphorus content. The amount is in the range of 0.08% by mass or more and 0.25% by mass or less, and the chlorine content is in the range of more than 0.00% by mass and 0.35% by mass or less.

The milk protein concentrate according to the sixth aspect of the present invention is a milk protein concentrate produced by the above-mentioned method for producing a milk protein concentrate. The composition of this milk protein concentrate is such that the protein content is in the range of 9.0% by mass or more and 15.5% by mass or less per 20% by mass of the total solid content, and the ash content is 0. It is in the range of 40% by mass or more and 1.55% by mass or less, the sodium content is in the range of 0.01% by mass or more and 0.10% by mass or less, and the potassium content is 0.05% by mass or more. It is in the range of 0.40% by mass or less, the calcium content is in the range of 0.15% by mass or more and 0.40% by mass or less, and the magnesium content is more than 0.00% by mass and 0.03% by mass. % Or less, phosphorus content is 0.08% by mass or more and 0.25% by mass or less, and chlorine content is more than 0.00% by mass and 0.35% by mass or less. Uchidea is, heat coagulation time is greater than or equal to 4 minutes at 130 ° C. in the range of pH6.45 than 6.75 or less. Then, using this milk protein concentrate as a raw material, various dairy products rich in milk flavor can be produced.

Milk protein concentrate according to the seventh aspect of the invention provides a milk protein concentrate according to the sixth station surface, is liquid.

The dairy product according to the eighth aspect of the present invention is produced from the above-mentioned milk protein concentrate as a raw material. The dairy product is preferably fermented milk.

The method according to the ninth aspect of the present invention is a method for weakening the saltiness and "egumi" of a dairy product without impairing the milk flavor of the dairy product, and when the dairy product is produced, the pH is 6.45 or more 6 A method using a milk protein concentrate having a thermal coagulation time of 4 minutes or more at 130 ° C. within the range of .75 or less.

The plot showing the influence of pH on the heat coagulation time of the milk concentrate according to Example 1 is shown together with the plot diagram showing the influence of pH on the heat coagulation time of the milk concentrate according to Comparative Example 1. Is.

The milk concentrate according to the embodiment of the present invention is produced through a pH adjusting step and a milk concentrate preparation step. Hereinafter, the milk concentrate will be described in detail, and then its production method and its use will be described in detail.

<Milk concentrate>
The milk concentrate according to the embodiment of the present invention is raw milk, milk or special milk or defatted milk (raw milk, milk or special milk from which milk fat is removed) or partially defatted milk (from raw milk, milk or special milk). Concentrated milk (partially removed milk fat), for example, concentrated milk (raw milk, milk or special milk) specified in the "Ministry of Health and Welfare Ordinance on Ingredient Standards for Milk and Milk Products" Milk solids content of 25.5% or more and milk fat content of 7.0% or more) and non-fat concentrated milk (raw milk, milk or special milk from which milk fat content has been removed) The non-fat milk solid content is 18.5% or more, and the number of bacteria (per 1 g by the standard plate culture method) is 100,000 or less. Concentrated milk or special milk with a milk solid content of less than 25.5% (hereinafter referred to as "non-ministerial concentrated milk") "," Remove milk fat from raw milk, milk or special milk Milk Protein concentrate (Milk Protein), which may be a concentrated milk product having a non-fat milk solid content of less than 18.5% (hereinafter referred to as "non-ministerial defatted concentrated milk"). It is preferably Concentrate (hereinafter, also referred to as "MPC"). In the following, for convenience of explanation, raw milk, milk, special milk, skim milk and partially skim milk may be collectively referred to as "raw milk".

Further, the milk concentrate according to the embodiment of the present invention contains proteins in the range of 9.0% by mass or more and 15.5% by mass or less per 20% by mass of the total solid content, and 0.40% by mass or more and 1. Ash content in the range of 55% by mass or less, sodium (Na) in the range of 0.01% by mass or more and 0.10% by mass or less, potassium (K) in the range of 0.05% by mass or more and 0.40% by mass or less. ), Calcium (Ca) in the range of 0.15% by mass or more and 0.40% by mass or less, Magnesium (Mg) in the range of more than 0.00% by mass and 0.03% by mass or less, 0.08% by mass or more It contains phosphorus (P) in the range of 0.25% by mass or less and chlorine (Cl) in the range of more than 0.00% by mass and 0.35% by mass or less.

The protein content of the milk concentrate according to the embodiment of the present invention is preferably in the range of 10.0% by mass or more and 15.5% by mass or less per 20% by mass of the total solid content. It is more preferably in the range of 10.5% by mass or more and 15.0% by mass or less, further preferably in the range of 11.0% by mass or more and 15.0% by mass or less, and 11.5% by mass or more. It is more preferably in the range of 14.5% by mass or less, further preferably in the range of 12.0% by mass or more and 14.0% by mass or less, and 12.5% by mass or more and 13.5% by mass or less. It is particularly preferable that it is within the range of.

Further, the ash content of the milk concentrate according to the embodiment of the present invention is preferably in the range of 0.50% by mass or more and 1.55% by mass or less per 20% by mass of the total solid content. It is more preferably in the range of 0.55% by mass or more and 1.50% by mass or less, further preferably in the range of 0.60% by mass or more and 1.50% by mass or less, and 0.65% by mass or more. It is more preferably in the range of 1.45% by mass or less, and particularly preferably in the range of 0.70% by mass or more and 1.45% by mass or less.

Further, the content of sodium (Na) in the milk concentrate according to the embodiment of the present invention is in the range of 0.01% by mass or more and 0.09% by mass or less per 20% by mass of the total solid content. Is more preferable, and it is more preferably in the range of 0.01% by mass or more and 0.08% by mass or less, and further preferably in the range of 0.02% by mass or more and 0.08% by mass or less, 0.02. It is particularly preferably in the range of mass% or more and 0.07 mass% or less.

Further, the content of potassium (K) in the milk concentrate according to the embodiment of the present invention depends on the content of sodium (Na), but is 0.05% by mass or more per 20% by mass of the total solid content. It is preferably in the range of 0.38% by mass or less, more preferably in the range of 0.05% by mass or more and 0.36% by mass or less, and 0.06% by mass or more and 0.34% by mass or less. It is more preferably within the range, and particularly preferably within the range of 0.06% by mass or more and 0.32% by mass or less. The potassium (K) content is preferably 3 times or more and 4 times or less of the sodium (Na) content, and is 3.2 times or more and 3.9 times or less of the sodium (Na) content. More preferably, it is more preferably 3.4 times or more and 3.8 times or less of the sodium (Na) content, and 3.6 times or more and 3.7 times or less of the sodium (Na) content. It is particularly preferable to have.

The calcium (Ca) content of the milk concentrate according to the embodiment of the present invention is in the range of 0.15% by mass or more and 0.36% by mass or less per 20% by mass of the total solid content. Is more preferable, and it is more preferably in the range of 0.16% by mass or more and 0.34% by mass or less, further preferably in the range of 0.17% by mass or more and 0.32% by mass or less, and 0.18. It is particularly preferably in the range of mass% or more and 0.30 mass% or less.

Further, the content of magnesium (Mg) in the milk concentrate according to the embodiment of the present invention is within the range of more than 0.00% by mass and 0.02% by mass or less per 20% by mass of the total solid content. Is preferable, and it is more preferably in the range of more than 0.00% by mass and 0.01% by mass or less.

Further, the phosphorus (P) content of the milk concentrate according to the embodiment of the present invention shall be in the range of 0.10% by mass or more and 0.24% by mass or less per 20% by mass of the total solid content. Is more preferable, and it is more preferably in the range of 0.11% by mass or more and 0.24% by mass or less, further preferably in the range of 0.12% by mass or more and 0.23% by mass or less, and 0.13. It is particularly preferably in the range of mass% or more and 0.23 mass% or less.

Further, the chlorine (Cl) content of the milk concentrate according to the embodiment of the present invention shall be in the range of 0.01% by mass or more and 0.30% by mass or less per 20% by mass of the total solid content. Is more preferable, and it is more preferably in the range of 0.03% by mass or more and 0.30% by mass or less, and further preferably in the range of 0.05% by mass or more and 0.25% by mass or less, 0.07. It is particularly preferably in the range of mass% or more and 0.25 mass% or less.

Further, the total solid content of the milk concentrate according to the embodiment of the present invention is usually in the range of 14% by mass or more and 22% by mass or less, and in the range of 16% by mass or more and 22% by mass or less. It is more preferable that it is in the range of 18% by mass or more and 22% by mass or less, and further preferably it is in the range of 20% by mass or more and 22% by mass or less.

Further, the heat coagulation time of the milk concentrate according to the embodiment of the present invention at 130 ° C. (the time until the coagulant is generated in the milk concentrate and the time until the viscosity of the milk concentrate increases) is 2. It is preferably more than 1 minute, more preferably 4 minutes or more, further preferably 6 minutes or more, and particularly preferably 8 minutes or more.

<Manufacturing method of milk concentrate>
The milk concentrate according to the embodiment of the present invention is produced through a pH adjusting step and a milk concentrate preparation step as described above. When the milk concentrate according to the embodiment of the present invention is skim milk concentrate, skim milk concentrate other than the ministerial ordinance, or milk protein concentrate, it is preferable to provide a skim milk preparation step before the pH adjustment step. .. Further, it is preferable that the pH readjustment step is provided after the milk concentration preparation step. Hereinafter, these steps will be described in detail.

(1) Skim milk preparation step In the skim milk preparation step, skim milk or partially skim milk is prepared from raw milk, milk or special milk. The term "skimmed milk" as used herein means that the milk fat content is removed from raw milk, milk or special milk, and for example, "milk fat content of raw milk, milk or special milk is less than 0.5%". And so on. Further, the term "partially defatted milk" as used herein means that the milk fat content is partially removed from raw milk, milk or special milk, and for example, "the milk fat content of raw milk, milk or special milk is 0". It is within the range of 5.5% or more and less than 3.0%. " As described above, the skim milk preparation step does not necessarily have to be carried out. You may purchase a commercially available skim milk concentrate or non-Ministerial skim milk concentrate and use it as a raw material milk (starting material) in the pH adjustment step.

Examples of the method for preparing defatted milk or partially defatted milk from raw milk, milk or special milk include a method of centrifuging the milk fat of raw milk, milk or special milk (hereinafter, also referred to as "centrifugation method"). , Raw milk, milk or special milk milk fat is subjected to membrane separation treatment (hereinafter, also referred to as "membrane separation method". For example, there is precision filtration treatment) and the like. When the centrifugation method is adopted, it is preferable to centrifuge the milk fat while keeping the temperature of raw milk, milk or special milk within the range of 45 ° C. or higher and 55 ° C. or lower. In such cases, it is preferable to cool the obtained skim milk or partially skim milk before the pH adjusting step. In such a case, the cooling temperature is preferably in the range of 10 ° C. or lower, which is the temperature at which the skim milk or partially skim milk remains liquid, and more preferably in the range of 1 ° C. or higher and 5 ° C. or lower.

(2) pH Adjusting Step In the pH adjusting step, the pH of the raw material milk (for example, cooled raw material milk) is adjusted within the range of 5.5 or more and less than 6.5, and the pH adjusting raw material milk is prepared. The pH is preferably a predetermined value from the viewpoint of easy adjustment of the amount of alkali added and easy maintenance of low viscosity. That is, in such a case, in the pH adjusting step, the pH of the pH-adjusted raw material milk is preferably in the range of 5.5 or more and 6.2 or less, and more preferably in the range of 5.5 or more and 6.0 or less. It is preferably in the range of 5.5 or more and 5.8 or less, and more preferably. Since the pH of the raw material milk is usually in the range of 6.4 or more and 7.2 or less, an acid is used in this pH adjusting step. As this acid, an acid that can be added to food, that is, an acid that is harmless to the human body, for example, hydrochloric acid, lactic acid, acetic acid, or the like is used. In this way, when the pH of the raw material milk is adjusted to the acidic side, calcium ions, magnesium ions, etc. electrostatically attached to the protein are dissociated from the protein in the pH-adjusted raw material milk. Then, by appropriately adjusting the pH of the raw material milk within the above range, the content (number) of calcium ions, magnesium ions, etc. dissociated in the raw material milk can be adjusted.

In this pH adjusting step, it is preferable to allow the pH-adjusted raw material milk to stand or stir for a predetermined time after adding the above-mentioned acid to the raw material milk. Here, the predetermined time is preferably 0.5 hours or more, more preferably 1 hour or more, further preferably 1.5 hours or more, and particularly preferably 2 hours or more. The predetermined time is not particularly limited, but the predetermined time is, for example, preferably 10 hours or less, more preferably 8 hours or less, further preferably 6 hours or less, and 4 hours or less. Is particularly preferable. Further, in this pH adjusting step, it is preferable to allow the pH adjusting raw material milk to stand or stir at a predetermined temperature. Here, the predetermined temperature is preferably in the range of 25 ° C. or higher, which is the temperature at which the pH-adjusted raw material milk remains liquid, and more preferably in the range of 1 ° C. or higher and 20 ° C. or lower. It is more preferably in the range of ° C. or lower, and particularly preferably in the range of 3 ° C. or higher and 10 ° C. or lower.

(3) Milk Concentrate Preparation Step In the milk concentrate preparation step, after the pH adjustment step, the pH-adjusted raw material milk is ultrafiltered to prepare a milk concentrate (milk protein concentrate). At this time, calcium ions, magnesium ions, etc. dissociated in the pH adjusting step are separated from the pH adjusting raw material milk (or milk concentrate) as a permeate. As a result, the desired "milk concentrate with reduced calcium and magnesium content (concentration)" can be obtained. As the ultrafiltration membrane used for the ultrafiltration treatment, a flat membrane, a hollow fiber membrane, a spiral membrane, a ceramic membrane, a rotating membrane, a vibrating membrane, etc. are used, and the fractional molecular weight of the ultrafiltration membrane is , 8000 Da or more and 12000 Da or less, more preferably 9000 Da or more and 11000 Da or less, and further preferably 9500 Da or more and 10500 Da or less. By the way, the lower limit of this concentration ratio may change depending on the type of raw milk, but for example, when the raw milk is skim milk, this concentration ratio is preferably 2.5 times or more. It is more preferably twice or more, and when the raw milk is raw milk, the concentration ratio is preferably 1.5 times or more, and more preferably 2 times or more. The upper limit of the concentration ratio can be determined by the degree of pressure resistance of the ultrafiltration membrane and the ultrafiltration device. For example, when the raw milk is skim milk, the concentration ratio is 4 times or less. It is preferable that it is 3.5 times or less, and when the raw milk is raw milk, the concentration ratio is preferably 3 times or less, and more preferably 2.5 times or less. According to the diligent study of the present inventor, the higher the concentration ratio, the higher the thermal stability of the milk concentrate, the smaller the amount of alkali added in the pH readjustment (neutralization) step, and after the pH readjustment step. , It has been clarified that the viscosity of the milk concentrate is low.

(4) pH readjustment step In the pH readjustment step, the pH of the milk concentrate (for example, cooled milk concentrate, milk concentrate at room temperature) is adjusted within the range of 6.5 or more and 7.0 or less. A pH-adjusted milk concentrate (hereinafter also referred to as "pH-adjusted milk concentrate") is prepared. The pH is preferably a predetermined value from the viewpoint of easy improvement of thermal stability and easy maintenance of low viscosity. That is, in the pH readjustment step, the pH of the pH-adjusted milk concentrate is preferably in the range of 6.5 or more and 6.9 or less, and preferably in the range of 6.5 or more and 6.8 or less. More preferably, it is in the range of 6.5 or more and 6.7 or less. Since the pH of the milk concentrate is usually in the range of 5.5 or more and less than 6.5, alkali is used in this pH readjustment step. As this alkali, an alkali that can be added to food, that is, an alkali that is harmless to the human body, for example, sodium hydroxide, potassium hydroxide, potassium carbonate, or the like is used. At this time, the alkali is preferably used in the form of a dilute aqueous solution, more preferably in the form of a 1 to 3 N alkaline aqueous solution, and further preferably in the form of a 2N alkaline aqueous solution. preferable. At this time, the ratio of sodium hydroxide and potassium hydroxide is adjusted so that the ratio of sodium ion / potassium ion in the milk concentrate is the ratio of sodium ion / potassium ion in the raw material milk or a ratio close to the ratio. It is preferable to use a mixed aqueous solution, specifically, it is more preferable to use a mixed aqueous solution in which sodium hydroxide: potassium hydroxide is 2 to 4: 8 to 6, and sodium hydroxide: potassium hydroxide is 3: 7. It is more preferable to use a mixed aqueous solution of.

In this pH readjustment step, it is preferable to allow the pH-adjusted milk concentrate to stand or stir for a predetermined time after adding the above-mentioned alkali to the milk concentrate. Here, the predetermined time is preferably 0.1 hours or more, more preferably 0.3 hours or more, further preferably 0.5 hours or more, and particularly preferably 1 hour or more. preferable. The upper limit of the predetermined time is not particularly limited, but the predetermined time is, for example, preferably 10 hours or less, more preferably 8 hours or less, further preferably 6 hours or less, and 4 hours or less. Is particularly preferable. Further, in this pH readjustment step, it is preferable to allow the pH-adjusted milk concentrate to stand or stir at a predetermined temperature. Here, the predetermined temperature is preferably in the range of 25 ° C. or higher, which is the temperature at which the pH-adjusted milk concentrate remains liquid, and more preferably in the range of 1 ° C. or higher and 20 ° C. or lower. It is more preferably in the range of 15 ° C. or lower, and particularly preferably in the range of 3 ° C. or higher and 10 ° C. or lower.

<Use of milk concentrate>
The milk concentrate according to the embodiment of the present invention can be used as a component of a raw material for dairy products. That is, this milk concentrate may be used alone as a raw material (raw milk) for dairy products, or water, raw milk, sterilized milk, skim milk, skim milk powder, skim milk powder, skim milk concentrate, skim milk. It may be mixed with other raw materials such as concentrated milk, buttermilk, butter, cream, and cheese and used as a raw material for dairy products (a part of raw milk, etc.).

The above-mentioned dairy products include, for example, milk beverages (including processed milk), yogurts, lactic acid bacteria beverages, fermented milk, ice creams, creams, cheeses and the like. If necessary, any ingredient can be added to this dairy product. There are no particular restrictions on such arbitrary ingredients, but sweeteners, acidulants, vegetables, fruits, seeds, vegetable juices, fruit juices, seed juices, and vegetables, which are ingredients contained in general dairy products. Fruit and seed extracts, vitamins, minerals, nutrients such as peptides and amino acids, useful microorganisms such as lactic acid bacteria, bifidus bacteria, propionic acid bacteria, cultures of useful microorganisms, fermented products of useful microorganisms, royal jelly, Includes existing functional materials such as glucosamine, astaxanthin, polyphenols, fragrances, pH regulators, excipients, acidulants, colorants, emulsifiers, preservatives and the like. At this time, the sweeteners include, for example, glucose, fructose, malt sugar, sucrose, oligosaccharide, sugar, honey, maple syrup, agave syrup, balm sugar, moraces (sugar honey), water candy, glucose-fructose liquid sugar, trehalose, and multitose. , Palatinose, xylitol, sorbitol, licorice extract, stevia-processed sweetener, Rakan fructose extract, somatin, glycerin, curculin, monerin, miraculin, erythritol and the like. Since these sweeteners can not only give sweetness to dairy products but also suppress sourness and "harshness", they are preferably added positively during the production of dairy products.

When the above-mentioned dairy product is fermented milk, this milk concentrate may be used as a component of a raw material mix of fermented milk. In the preparation of this fermented milk raw material mix, for example, raw materials such as milk concentrate and other optional ingredients (for example, sweeteners, acidulants, minerals, vitamins, flavors, etc.) are added (blended), heated, and mixed.・ It is dissolved. Then, in addition to the milk concentrate, water, raw milk, sterilized milk, whole fat powdered milk, whole fat concentrated milk, buttermilk, butter, cream, cheese, etc. are added, heated, mixed, dissolved, etc. to this raw material mix. You may. In addition, whey protein concentrate (WPC), whey protein isolate (WPI), α-lactalbumin (α-La), β-lactoglobulin (β-Lg), etc. are added and heated to this raw material mix. -You may mix and dissolve.

When the above-mentioned dairy product is fermented milk, the fermented milk is prepared in the same manner as in the conventional method for producing fermented milk, in the preparation step of the raw material mix, the (heating) sterilization step of the raw material mix, and the cooling step of the raw material mix. It is manufactured through processes such as a starter addition process, a fermentation process, and a cooling process of fermented milk. At this time, in the preparation process of the raw material mix, as described above, the raw materials are added, heated, mixed, dissolved (prepared) and the like. In each of the above-mentioned steps, general processing conditions at the time of producing fermented milk may be appropriately adopted. Further, the (heating) sterilization step of the raw material mix, the cooling step of the raw material mix, the addition step of the starter, the fermentation step and the cooling step of the fermented milk are preferably carried out in this order.

<Characteristics of milk concentrate>
The milk concentrate obtained as described above has a relatively high concentration of calcium, magnesium, etc., as compared with the conventional milk concentrate, but the thermal stability is satisfactorily improved or maintained. Dairy products prepared using this milk concentrate as a raw material have a relatively high concentration of calcium, magnesium, etc., as compared with conventional dairy products prepared using a milk concentrate as a raw material, but have a milk flavor and other physical characteristics. Good improvement or maintenance.

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples. The present invention is not limited to this embodiment.

(Example 1)
1. 1. Preparation of milk concentrate First, using a cream separator (Separator F-3 manufactured by elecrea, volume: 0.37 L), the raw milk was centrifuged at 50 ° C. (rotation speed: 7,000 to 8,000 rpm, treatment flow rate: 315 L / h). , Treatment time: 4.2 seconds, gravitational acceleration: 1500-4400 G) to prepare skim milk, and the skim milk was cooled to 5 ° C. (skimmed milk preparation step). Next, a 2N aqueous hydrochloric acid solution was added to the cooled skim milk to adjust the pH of the skim milk to 5.7, and the mixture was left at 5 to 10 ° C. for 2 hours (pH adjustment step). Next, using a hollow fiber membrane module (Romicon Hollow fiber CTG3 "HF25-43 PM-10 manufactured by Koch Co., Ltd., fractional molecular weight: 10,000 Da, membrane area: 2.3 m ² ), the left defatted milk was subjected to. A milk concentrate (milk protein concentrate) was produced by ultrafiltration (UF) treatment at a concentration ratio of 3.2 times (milk concentrate preparation step).

Before the ultrafiltration treatment of the defatted milk using the hollow fiber membrane module, the hollow fiber membrane was washed with an alkaline aqueous solution to which chlorine was added at 200 ppm. Then, after cooling the hollow fiber membrane while circulating cold water (3 to 5 ° C.) through the hollow fiber membrane module, the cooling water was discharged from the hollow fiber membrane module. Then, the above-mentioned skim milk (5 to 10 ° C.) left unattended was put into a tank with a jacket having a capacity of 20 L. Then, when ultrafiltration of defatted milk using the hollow fiber membrane module, the hollow fiber membrane module is connected to this tank by a pipe or the like to indirectly cool the tank and this pipe. A cooling pipe was provided in the middle of the pipe to indirectly cool the pipe. The concentration ratio for ultrafiltration of skim milk is the amount of skim milk charged (treatment amount), the treatment flow rate of the permeate (permeation flow rate), the concentration of the total solid content of the holding liquid (concentrate), and the protein concentration. It was decided from the above.

Then, after dividing this milk concentrate into five, sodium hydroxide so that the ratio of sodium (ion) / potassium (ion) of each milk concentrate becomes equivalent to the ratio in milk (about 4/15). And a mixed aqueous solution of 2N sodium hydroxide / potassium hydroxide containing potassium hydroxide in a ratio of 3: 7 (molar ratio) was added to adjust the pH of each milk concentrate to 6.40 under a constant temperature environment of 20 ° C. , 6.45, 6.50, 6.60, 6.75 to prepare a pH-adjusted milk concentrate (pH readjusted milk concentrate) (pH readjustment step).

2. Physical characteristics confirmation test (1) Thermal stability confirmation test First, 4 mL of each pH readjusted milk concentrate was weighed in a 14 mL round bottom vial and sealed. Next, the round-bottomed vial is immersed in an oil bath at 130 ° C., and the pH-adjusted milk concentrate is concentrated while visually checking each pH-adjusted milk concentrate while shaking the round-bottomed vial. The time until the solidified product was generated in the product was measured, and this measured time was defined as the "thermal solidification time". Finally, 2 hours after the time of pH readjustment, the pH of each pH readjusted milk concentrate at 10 ° C. was measured, and the pH was taken as the pH of each pH readjusted milk concentrate.

The results of this confirmation test are shown in Table 1. In addition, a graph of the data shown in Table 1 is shown in FIG.

(2) Sensory test (2-1)
Fermented milk was prepared using the above pH readjusted milk concentrate as raw material milk, and a sensory test was conducted on the fermented milk. Hereinafter, the sensory test will be described in detail after explaining the method for preparing the fermented milk.

Each pH readjusted milk concentrate was sterilized by heating and stored in a sterilized vat (5 L stainless steel container). In this heat sterilization, the pH readjusted milk concentrate was heated at a temperature of 95 ° C. by a batch method using a vat.

Next, each pH readjusted milk concentrate that was sterilized by heating was placed in a bat and the temperature was adjusted to 43 ° C. (Mixed starter of Filth bacterium) was added so as to be 2% by mass, and they were stirred and held for 10 minutes.

Next, 70 g of each pH readjusted milk concentrate to which the lactic acid bacterium starter was added was filled in a cup containing about 100 mL. On the other hand, each pH readjusted milk concentrate remaining here was left in the vat. Subsequently, the cups and bats were placed in an incubator at 43 ° C. to ferment each pH readjusted milk concentrate. Then, when the pH of each pH readjusted milk concentrate reaches 4.6, the fermented milk in a cup is placed in a refrigerator (3 to 5 ° C.) and held overnight (about 12 hours) to be hard. A type of fermented milk was produced. On the other hand, when the pH of each pH readjusted milk concentrate reaches 4.6, the fermented milk in a vat is stirred and cooled in a cold water bath (3 to 5 ° C.) to produce a soft type fermented milk. Manufactured.

(2-2)
A panel of 5 people eats the above hard type fermented milk and soft type fermented milk in a cooled state (5 ° C), and has sweetness, saltiness, sourness, harshness, milk flavor, smoothness, and unpleasant odor. The strength (degree) was evaluated on a 5-point scale. At this time, the majority of the specialized panels said, "The fermented milk of Example 1 (described above) has less harshness and is richer in milk flavor and smoothness than the fermented milk of Comparative Example 1 (described later)." evaluated.

(Comparative Example 1)
In the preparation of the milk concentrate, the pH readjusted milk was prepared in the same manner as in Example 1 except that the pH adjusting step was omitted and the skim milk was subjected to ultrafiltration treatment without adjusting the pH of the cooled skim milk. A concentrate was prepared. Then, in the same manner as in Example 1, a thermal stability confirmation test was conducted on the pH-adjusted milk concentrate. In Comparative Example 1, the pH readjustment step was carried out only for comparison with Example 1 and Example 2, and the patentability of pH readjustment in the present invention is not denied.

The results of this confirmation test are shown in Table 1. In addition, a graph of the data shown in Table 1 is shown in FIG.

<Discussion on Examples and Comparative Examples>
As is clear from FIG. 1, in the range of pH 6.4 to 6.75, the pH readjusted milk concentrate prepared in Example 1 becomes the pH readjusted milk concentrate prepared in Comparative Example 1. In comparison, it was revealed that it was excellent in thermal stability. In the range of pH 6.4 to 6.5, the thermal stability of the pH readjusted milk concentrate prepared in Example 1 is at a level that can sufficiently withstand the production of fermented milk and the like, and the pH is high. Within the range of 6.5 to around 6.7, the thermal stability of the pH readjusted milk concentrate prepared in Example 1 should be evaluated as a significant level.

Claims (10)

A method for producing a milk protein concentrate, wherein the heat coagulation time at 130 ° C. is 4 minutes or more in the range of pH 6.45 or more and 6.75 or less.
A pH adjustment step for preparing skim milk by adjusting the pH of skim milk within the range of 5.5 or more and less than 6.5, and a pH adjustment step.
The first milk protein concentrate preparation step of preparing the first milk protein concentrate by ultrafiltration treatment of the pH-adjusted skim milk, and
A method for producing a milk protein concentrate, which comprises a pH readjustment step of adjusting the pH of the first milk protein concentrate within the range of 6.45 or more and 6.75 or less to prepare a second milk protein concentrate. The method for producing a milk protein concentrate according to claim 1, wherein in the pH adjusting step, the pH of the skim milk is adjusted within the range of 5.5 or more and 5.8 or less to prepare the pH adjusted skim milk. In the pH readjustment step, the pH of the first milk protein concentrate is 6.45 or more and 6.75 or less by adding a mixed aqueous solution of sodium hydroxide and potassium hydroxide to the first milk protein concentrate. The method for producing a milk protein concentrate according to claim 1 or 2, wherein the second milk protein concentrate is prepared within the range of. The method for producing a milk protein concentrate according to any one of claims 1 to 3, wherein the second milk protein concentrate is a liquid. The second milk protein concentrate has a protein content of 9.0% by mass or more and 15.5% by mass or less and an ash content of 0.40% by mass per 20% by mass of the total solid content. % Or more and 1.55% by mass or less, the sodium content is in the range of 0.01% by mass or more and 0.10% by mass or less, and the potassium content is 0.05% by mass or more and 0. It is in the range of 40% by mass or less, the calcium content is in the range of 0.15% by mass or more and 0.40% by mass or less, and the magnesium content is more than 0.00% by mass and 0.03% by mass or less. The phosphorus content is within the range of 0.08% by mass or more and 0.25% by mass or less, and the chlorine content is within the range of more than 0.00% by mass and 0.35% by mass or less. The method for producing a milk protein concentrate according to any one of claims 1 to 4. The protein content is in the range of 9.0% by mass or more and 15.5% by mass or less, and the ash content is 0.40% by mass or more and 1.55% by mass or less per 20% by mass of the total solid content. It is within the range, the sodium content is within the range of 0.01% by mass or more and 0.10% by mass or less, and the potassium content is within the range of 0.05% by mass or more and 0.40% by mass or less. , The calcium content is in the range of 0.15% by mass or more and 0.40% by mass or less, the magnesium content is in the range of more than 0.00% by mass and 0.03% by mass or less, and the phosphorus content. the amount is in the range of 0.25 mass% or more 0.08% by mass, the content of chlorine Ri der within the following ranges 0.00 mass percent 0.35 wt%,
A milk protein concentrate having a thermal coagulation time of 4 minutes or more at 130 ° C. in the range of pH 6.45 or more and 6.75 or less. The milk protein concentrate according to claim 6, which is liquid. A dairy product produced from the milk protein concentrate according to claim 6 or 7. The dairy product according to claim 8 , wherein the dairy product is fermented milk. When producing a dairy product, a milk protein concentrate having a heat coagulation time of 4 minutes or more at 130 ° C. in the pH range of 6.45 or more and 6.75 or less is used without impairing the milk flavor of the dairy product. A method of weakening the saltiness and "egumi" of the dairy product.

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