JP2900953B2 - Process for producing a milk fraction having a high content of α-lactalbumin and a product containing the fraction - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for separating and recovering a fraction having a high α-lactalbumin content from milk using a cross-flow MF membrane, and a product containing the fraction.

2. Description of the Related Art Conventionally and its background In general, whey protein is known to be used as a source of protein for breast milk substitutes or human or animal nutritional compositions because of its higher nutritional value and protein utilization efficiency than casein and soybean proteins. I have. In particular, when used as a substitute for breast milk, β-lactoglobulin (β-Lg), which is the main component of whey protein in cow's milk, is a protein that does not exist in breast milk and acts as an allergen for infant allergy.
-Lg is reduced or α-lactalbumin (α-lactalbumin
La) It is said that it is desirable to use a whey protein material having a high content.

Therefore, attempts have been made to reduce β-Lg from whey by-produced in the production of cheese or to increase the α-La content to effectively use whey protein.

That is, as a method for separating and recovering a fraction having a high α-La content, there have been many attempts to effectively utilize the difference in physical properties and / or chemical properties of each whey protein using whey as a starting material. It has been done. However, these methods have problems such as complicated steps, energy costs, low recovery rates, irreversible changes in proteins, and have not been scaled up to industrially feasible methods. . Recently, fractionation methods using a UF membrane include Peter Harris (JP-A-57-118758), Mowwa et al. (JP-A-56-36494) and Bottomley (JP-A-1-165343). In these methods, whey is used as a starting material. However, as a result of studying these methods as an actual problem, the pore sizes of UF membranes used industrially vary, and α-La (MW14000 Da) and β-Lg (MW3
6000 Da dimer) was difficult to properly fractionate.
As described above, all of the conventional methods use whey as a starting material, and there is no method for separating and recovering a fraction having a high α-La content using milk as a starting material.

On the other hand, at present, industrial technology of using UF membranes in the dairy industry is used for the concentration of whey protein concentrate (WPC), whole milk protein (TMP) and cheese milk, etc. It is only used to separate Regarding the application technology of the MF membrane, in the all-filtration method, the treatment capacity is reduced due to clogging of the membrane, and the original characteristics of the membrane cannot be maintained. It is just done. On the other hand, in recent years, a cross-flow system has been developed in which the disadvantages of the total filtration system have been improved, and its use for removing bacteria from milk, concentrating cells of lactic acid bacteria, removing fat from whey, and the like has been studied. However, using milk as a raw material
A method for separating and recovering a whey protein, particularly a fraction having a high α-La content, by MF membrane treatment has not been studied so far.

Problems to be Solved by the Invention As described above, in the step of separating and recovering a fraction having a high α-La content from whey using a membrane treatment technique, good separation and efficient recovery are difficult. Accordingly, the present invention has been made to solve the problems in the production associated with the conventional α-La separation and recovery.

Means for Solving the Problems The present invention provides a cross-flow MF membrane technology using ceramic and polymer membranes, and κ-casein and β-
By applying a complex between Lg, a whey protein fraction having a high α-La content is obtained on an industrial scale.
The resulting α-La-rich fraction may also be used as a milk replacer and a human or animal nutritional supplement.

That is, the present invention provides a high α-La content, which comprises subjecting the heat-treated milk to permeation through a cross-flow MF membrane treatment and separating and collecting a high α-La content fraction on the permeate side. It relates to a method for producing a milk fraction.

In the present invention, the heat treatment of the milk may be performed by heating the film during the cross-flow MF treatment. As described above, α-La and β-Lg are present in milk, for example, α-La and β-Lg in milk.
The molecular weight of La is 14000 Da and that of β-Lg is 36000 Da (present as a dimer). However, with such a difference in molecular weight, it is difficult to satisfactorily separate the two into a membrane.
β-Lg is a heat-sensitive protein, which forms a self-association or a complex with κ-casein of casein micelles by heating (Dairy Sci. Abst. 25 , 45 (1963), J. Dairy Sci. 48,
1161 (1965)). The present inventors have applied this property of β-Lg and the membrane separation technology that has been rapidly advanced recently to the advantage of increasing the apparent molecular weight of β-Lg by heating,
The α-La and β-Lg were successfully separated by performing cross-flow MF membrane treatment after widening the difference in molecular weight from -La. As a result, α-La could be obtained with good yield.

As the milk in the present invention, all milks such as cow's milk, goat's milk, sheep's milk and buffalo milk are used, regardless of the fat content.

In addition, the heat-treated milk may be pre-heated milk such as pasteurized milk, reduced milk (heat-concentrated milk powder dissolved in water or the like), and raw milk (including raw skim milk). And those that involve high temperatures during film processing. This heat treatment is desirably performed at 70 ° C. or higher, at which temperature β-Lg associates with and / or forms a complex with κ-casein of casein micelles that have been polymerized.

Cross-flow MF membrane processing is a technology that has developed rapidly recently. The cross-flow filtration is a method in which a supply liquid flows along a membrane surface and crosses perpendicularly to a flowing direction of a permeated liquid, unlike the conventional all-filtration method. Characteristically, the processing ability and the membrane fractionation property can be maintained well. Further, the MF membrane is a separation membrane in which the pore size is accurately measured using the particles as the object of separation. The pore diameter is from 0.01 μm to several μm, and the material is made of ceramic or polymer. In the present invention, it is desirable to use a membrane having a pore size of 0.05 to 1.0 μm. When the pore size is 0.05 μm or less, α-
Both La and β-Lg are difficult to pass through the membrane and cannot be fractionated well. Further, at a pore size of 1.0 μm or more, β-Lg having an increased apparent molecular weight by heating passes through the membrane together with α-La, and a part of casein micelles is also transmitted,
α-La cannot be fractionated. In addition, the operating conditions of the cross-flow MF membrane device are such that α-La and β-Lg can be efficiently separated by operating at a transmembrane pressure difference of 0.5 MPa or less and a membrane surface flow rate of 0.5 m / sec or more. .

The method of the present invention will be described with reference to Table 1. When non-heat-treated milk such as skim milk or whole fat milk is used as a raw material, when the heat treatment is performed, 70 ° C.
It is preferable to heat and cool as described above, and then process this at normal temperature with a cross-flow MF membrane. When the heat treatment is not performed, it is preferable that the cross-flow high-temperature MF membrane treatment is performed, and the complex formation of β-Lg and κ casein by heating and the membrane treatment are simultaneously performed. Further, when using heat-treated milk such as reduced skim milk, reduced whole fat milk,
This may be treated with a room temperature MF film. In this case, α
-La penetrates the membrane, and α-La having a high α-La content can be obtained. This permeate usually contains about 0.1% of α-La, lactose, ash and the like.

In the concentrated solution for this membrane treatment, the main components are β-Lg and casein, but α-La remains therein. In the present invention, a liquid containing no α-La, such as water, is added to the concentrated liquid to dilute it, and a DF (diafiltration) membrane treatment is performed to allow the remaining α-La to pass therethrough. Can be combined with the MF membrane-treated permeate.

The permeate obtained in this manner contains α
-In addition to La, lactose, ash, water and the like are contained. Therefore, in the present invention, only the α-La may be fractionated and concentrated from the permeate using a UF membrane through which the α-La does not pass. As the UF membrane used here, since the molecular weight of α-La is 14000 Da, a membrane having a molecular weight cut off of substantially 14000 Da is used.

The concentrate thus obtained may be used as it is or subjected to drying means such as spray drying, freeze drying or the like to obtain a powder as a powdered milk powder for childcare or the like as a substitute for breast milk, or as a nutritional composition for humans or animals. Can be used.

Effect of the Invention According to the method of the present invention, a milk fraction having a high α-lactalbumin content can be separated and recovered from milk using a cross-flow MF membrane with high yield.

Then, the dried powder of this fraction or a product obtained by adding it to infant milk powder or the like has high nutritional value and protein utilization efficiency.

 Next, the present invention will be specifically described with reference to examples.

Example 1 As skim milk, skim milk powder manufactured by Snow Brand Milk Products Co., Ltd. was used.

This skim milk powder must be at least 75% when skim milk is concentrated and dried.
Heat treated at 15 ° C for 15 minutes.

 This skim milk powder was reduced with deionized water.

The analysis value (% by weight) of the reduced skim milk was as follows.

Total solids 7.5 protein (N × 6.38) 3.1 α- La / β-Lg 0.34 a fat 0.05 carbohydrate 3.68 Ash content 0.67 pH 6.5 reconstituted skim milk 20kg of membrane area 0.35 m ² NGK Co. ceramic membrane (alpha -Alumina) monolith type 948F, pore size
Cross-flow MF membrane filtration was performed using 0.1 μm. The operating conditions were as follows: temperature 12 ° C, average operating pressure 0.1MPa, membrane surface flow rate 1.
It was 6 m / sec. Concentration was performed up to a concentration ratio of 2 to obtain 10 kg of a concentrate and 10 kg of a permeate, respectively. 12.9% α-La and 1.8% β-Lg of the initial skim milk were transferred to the permeate. Due to the membrane treatment, the ratio of α-La / β-Lg is 0.34 in skim milk.
However, in the permeate, 2.43 and α-La showed high values.

Further, 10 kg of this concentrated liquid, the amount of concentrated milk is maintained at 10 kg,
The DF membrane treatment was performed while adding deionized water to the concentrated milk. In other words, diamond filtration (DF) was performed.
When 10 kg of the amount of permeate (= the amount of water) was obtained, the treatment was terminated. At this time, 22.8% of concentrated milk in 10 kg of permeate
Α-La and 2.9% β-Lg migrated, and the ratio of α-La / β-Lg in the permeate by diamond filtration was 2.5%.
Α-La also showed a high value of 1 here. After all, double concentration,
3.2.8% of α-La and 4.
6% of β-Lg migrated to the permeate side, and the value of β-lactoglobulin was lower than that of α-lactalbumin.

Example 2 Raw skim milk comprising the following components was used (% by weight).

Total solids 8.81 Protein (N x 6.38) 3.31 α-La / β-Lg 0.33 Fat 0.12 Carbohydrate 4.64 Ash 0.74 pH 6.6 100 kg of this raw skim milk in a Fordra tank at 85 ° C, 1
Was heated for 10 minutes, membrane area 0.42 m ² of Millipore ceramic membranes Serafuro, using a pore size 0.2 [mu] m, cross-flow M
F membrane filtration was performed. The operating conditions were a temperature of 50 ° C., an average operating pressure of 0.1 MPa, and a membrane surface flow rate of 2.0 m / sec. The same concentration and diafiltration as in Example 1 were performed.

The transfer rates of α-La and β-Lg to the filtrate obtained by 5-fold concentration were 37.2% and 5.2%, respectively, and the ratio of α-La / β-Lg was 0.33 in skim milk. , The permeate is 2.56,
A permeate having a high α-La content was obtained.

The transfer rates to the permeate obtained by diamond filtration were α-La 34.2% and β-Lg 4.4%, respectively.
The ratio of -Lg was 2.80, and a fraction having a high α-La content was obtained. As a result, about 58.6% of α-La and about 9.8% of β-Lg migrated to the permeate side by 5-fold concentration and 1-time diafiltration, and α-La was compared to β-Lg as in Example 1. Was high.

Example 3 150 kg of the α-La-enriched permeate obtained in Examples 1 and 2
Was used to concentrate and purify the protein. The components of the permeate used are shown below (% by weight).

Total solids 4.18 Protein (N x 6.38) 0.39 (Pure protein 0.12) Fat 0 Carbohydrate 3.47 Ash 0.32 pH 6.5 UF membrane GR81PP manufactured by DOW, fractionation molecular weight 6000Da, 0.36m
² was attached to DOW UF Lab-20, concentrated 50 times and 3 kg
Was obtained. The components (% by weight) of the concentrated liquid were 20.90 total solids protein (N x 6.38) 8.94. (Pure protein 6.00) fat 0 saccharide 10.38 ash 1.58 pH 6.2. Α-La and β-L by SDS-PAGE analysis
The g concentrations were 3.38% and 1.24%, respectively, and the ratio of α-La / β-Lg was 2.7, the same as the value before treatment.

Equivalent diamond filtration was performed to further increase the protein concentration. For this, 9 kg of deionized water, corresponding to three times the volume of the concentrate, were added. The components (wt%) of the 3 kg concentrate obtained were: total solids 8.89 protein (N x 6.38) 6.89 (pure protein 6.00) Fat 0 saccharide 1.3 Ash 0.80 pH 6.8, protein in total solid Was 77.5%. SDS
According to -PAGE, the concentrations of α-La and β-Lg in the concentrated solution were 3.36% and 1.20%, respectively, and the ratio of α-La / β-Lg was the same as the value before the treatment.

Example 4 The concentrated liquid described in Example 3 (total solid content: 20.90%, protein: 8.94%, fat: 0%, carbohydrate: 10.38%, ash content: 1.58%) was desalted by a conventional method, and the desalted concentrated liquid (total solid content) 18.12%, protein 8.05%, fat 0%, carbohydrate 9.90%, ash 0.17%) 10
After dissolving 6.4 kg of casein, 32.6 kg of lactose, and 2 kg of vitamin and mineral components in 0.6 kg, 27.6 kg of vegetable oil was mixed and homogenized. The obtained solution was sterilized, concentrated and dried by a conventional method to obtain 100 kg of milk powder as a substitute for breast milk.

Example 5 19.3 k of skim milk powder was added to 116.7 kg of the desalted concentrated solution described in Example 4.
g, 32.1 kg of lactose and 0.8 kg of vitamin and mineral components were dissolved, and then 27.7 kg of vegetable oil was mixed and homogenized. The obtained solution was sterilized, concentrated and dried by a conventional method to obtain 100 kg of milk powder as a substitute for breast milk.

Example 6 28% of dextrin was added to 288 kg of the desalinated concentrate described in Example 4.
After dissolving 5 kg and 1.6 kg of vitamin and mineral components, 16.4 kg of vegetable oil was mixed and homogenized. The obtained solution is sterilized, concentrated and dried by a conventional method to obtain a powdered nutritional food 100k.
g was obtained.

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Suzuka Nishizaki 473-3, Shinmeinai, Satte-shi, Saitama (58) Field surveyed (Int. Cl. ⁶ , DB name) A23J 1/00-7/00

Claims (9)

(57) [Claims] 1. A method comprising subjecting milk subjected to heat treatment or simultaneously with heat treatment to cross-flow microfiltration (MF) membrane treatment to separate and collect a fraction having a high α-lactalbumin content toward the permeate. For producing a milk fraction having a high content of α-lactalbumin characterized by the following: 2. The α according to claim 1, wherein one or more milks selected from the group consisting of pasteurized milk, reduced milk, heat concentrated milk and preheated raw milk are used as the heat-treated milk. -Method for producing a milk fraction having a high lactalbumin content 3. A milk-paint having a high α-lactalbumin content according to claim (1) or (2), wherein the milk which has been heated to 70 ° C. or higher and cooled to 69 ° C. or lower is subjected to room temperature cross-flow MF membrane treatment. Minute manufacturing method 4. The α-lactalbumin content according to (1) or (2), wherein a heat-resistant membrane is used as the cross-flow MF membrane, and the milk is subjected to a cross-flow MF membrane treatment at a temperature of 70 ° C. or higher. High milk fraction production 5. A cross-flow MF membrane made of ceramic or polymer and having a pore size of 0.05 to 1.0 μm.
As the operating condition of the cross-flow MF membrane device, the transmembrane pressure is 0.
The method for producing a milk fraction having a high content of α-lactalbumin according to any one of claims (1) to (4), wherein the method is carried out at 5 MPa or less and at a membrane surface flow rate of 0.5 m / sec or more. 6. The heat-treated milk or the milk is subjected to a cross-flow MF membrane treatment at the same time as the heat treatment, and the concentrated solution is further subjected to a diafiltration (DF) membrane treatment so that the permeated liquid is subjected to a cross-flow MF membrane. A method for producing a milk fraction having a high α-lactalbumin content, which comprises efficiently collecting a fraction having a high α-lactalbumin content in addition to a permeate. 7. The cross-flow with the DF membrane permeate according to claim (6).
A method for producing a milk fraction having a high α-lactalbumin content, comprising treating a liquid combined with an MF membrane permeate and treating the liquid with a UF membrane to recover a concentrated liquid. 8. An α-protein obtained by spray-drying or freeze-drying the fraction obtained according to any one of claims (1) to (7).
Milk fraction powder with high lactalbumin content 9. A breast milk substitute or a nutritional composition for humans or animals containing the fraction obtained according to any one of claims (1) to (8).