JPH01124351A - Preparation of curd of milks - Google Patents

Abstract

PURPOSE:To obtain high-quality curd of milks readily and inexpensively, by making alkaline milk into weak alkalinity, neutralizing with a buffer solution of alkaline metal acetate acidified with acetic acid and further subjecting to dielectric heating treatment. CONSTITUTION:Animal milk such as cow's milk or goat's milk or powdered milk is blended with an alkaline aqueous solution of potassium carbonate and adjusted to pH about 8-10 to give alkali milk. Then the milk is mixed with a buffer solution of acetic acid which contains an alkaline earth metal acetate and/or carbonate and adjusted to pH 4.0-4.2 with acetic acid to give weakly acidic neutralized milk. Then when the neutralized milk is subjected to dielectric heating treatment by microwave, the whole milk is uniformly heated and evolved carbon dioxide gas is made into microfoams to give uniform, smooth and fine curd. Thus curd having the same qualities as those of cured by enzymatic method is produced readily in a short time and inexpensively.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for preparing dairy curd which is smooth, fine-textured and capable of retaining a fresh milk odor.

[Conventional technology and problems]

Milk curd, which is the raw material for processed dairy products such as cheese, yogurt, and caseinate sugar, has traditionally been produced by (1) directly adding inorganic or organic acids to adjust the pH to the same level as milk protein;
The following methods are known: (2) a method using lactic acid fermentation, and (3) an enzymatic method using Renne Soto.

In the acid addition method (1), acetic acid, citric acid, malic acid, fumaric acid, lactic acid, hydrochloric acid, etc. are used as acids, and the time required for milk coagulation is short, but the resulting curd is In addition to having the disadvantage of having a rough texture, there is also the problem that the pH is as low as about 4, so it has a strong sour taste and loses the milk odor represented by the butyric acid odor. When using the lactic acid fermentation method (2), fine-grained and smooth curds can be obtained, but even under optimal conditions for lactic acid generation, a long processing time of 24 to 72 hours is required, and the resulting curds are not as good as (1). The pH is about 4, which is the same as when oxygen is added, and it has a strong sour taste.

On the other hand, the enzymatic method (3) is a method that has been used since ancient times, requires less processing time, and the resulting curd is smooth and retains the milky odor, making it the most suitable method. There are reports that the enzyme net can only be collected from calves, is expensive, and requires skill in adjusting the processing conditions.

An object of the present invention is to provide a method for easily and inexpensively preparing dairy curd having a quality comparable to that obtained by enzymatic methods.

[Means for solving problems]

The method for preparing milk curd of the present invention that achieves the above purpose includes: (1) a step of converting milk into weakly alkaline alkaline milk;
) adding an acetic acidic buffer containing an acetate and/or carbonate of an alkali metal and/or alkaline earth metal to the alkaline milk to obtain a weakly acidic neutralized milk;
and (to) a step of dielectrically heating the neutralized milk.

[Function and Examples]

The present invention basically consists of the three steps described above.

In other words, the first step is to convert milk such as milk into alkaline milk.
The second step is to make the neutralized milk weakly acidic with an acetic acid buffer, and the third step is to dielectrically heat the neutralized milk.

The first step is a treatment aimed at dissolving the milk with an alkali and adding carbonate ions.The first step is to dissolve the milk with an alkali and add carbonate ions. Add.

Examples of the milk processed by the present invention include animal milk from cows, goats, etc., and milk powder obtained by processing them (regardless of whether it is skim milk powder or whole milk powder), which is resuspended in water. . These milks have a non-fat milk solids content of 8 to 1
It is preferable to adjust the amount to 6% (weight %, the same applies hereinafter).

The method for obtaining alkaline milk in the first step is most preferably carried out by adding an alkaline aqueous solution as described above. Examples of alkaline aqueous solutions include sodium hydroxide,
potassium hydroxide, calcium hydroxide, calcium oxide,
Sodium carbonate, potassium carbonate, etc. can be used, but alkali metal carbonates, particularly potassium carbonate, are preferred because they are weakly alkaline and have a warm action. It is preferable that the pH of the alkaline aqueous solution is usually about 8.0 to 10. If it is a strong alkali, a local increase in pH will be observed upon addition, which will cause irreversible denaturation of milk proteins such as casein, which is not preferable. Addition of alkaline aqueous solution is
In order to avoid local pH increases, the aqueous milk solution is gradually added with sufficient stirring and stopped when the desired pH is reached.

Next, in a second step, an acetic acidic buffer is added to the alkaline milk to obtain neutralized milk. The important points in this second step are the preparation of the buffer solution and the pH of the neutralized milk.

Acetate buffers contain acetates and/or carbonates of alkali metals and/or alkaline earth metals, and the pH is adjusted by acetic acid.

Examples of the salts to be included include acetates or carbonates of sodium, calcium, magnesium, potassium, and the like. One or more of these salts may be used to form an aqueous solution.

The concentration is preferably 6 to 10%, particularly 8±0.8%.

Acetic acid is added to an aqueous solution of such salts to adjust the pH to 3.9-4.
3. Preferably, the acetate buffer is 4.0 to 4.2, but if carbonate is used as the salt, it is important to heat the solution after adding acetic acid to sufficiently dissipate carbon dioxide gas. If heat treatment is not performed, free carbon dioxide gas may be contained, which is not preferable. The addition of salts has the effect of replenishing the resulting milk curd with physiologically useful minerals.

A particularly preferred composition of the acetate buffer is 3 to 8 % of each of sodium acetate, calcium acetate, and magnesium acetate.
% (preferably 5-6%), 4-9% (preferably 6-6%)
7%) and 1 to 5% (preferably 2 to 3%),
The pH was adjusted to 4.0 to 4.2 with acetic acid. Combinations of these salts as carbonates are also preferably used, but in that case, only the sodium carbonate should be used in twice the molar amount. When such a combination of salts is used, a particularly smooth curd with fine beans and good emulsifying power can be obtained, and the recovery rate of proteins such as lactones, albumin, and globulin as well as useful nitrogen-containing compounds can be improved. becomes higher.

Next, the acetate buffer is added to obtain neutralized milk. Here, the basic difference from the conventional acid addition method is that in the acid addition method, milk protein of milk is solidified to an isoelectric point (I)+1. Normal pH
Acid was added until the milk reached 4.7, and coagulation occurred at this point, but in the second step of the present invention, the addition of an acetate buffer is a weakly acidic solution in which the milk does not coagulate, or is at most semi-coagulated. It is unique in that it only lowers the pH to . That is, in the present invention, complete coagulation is not achieved by adding this acid. The pH of neutralized milk varies depending on the milk protein content in the starting material, the initial pH, etc., but is usually 5.7 to 5.85 or higher, preferably 5.7 to 5.
It is 83. However, even at these pH values, if the milk is completely coagulated, a higher pH value must be used. The acetate buffer is added little by little while stirring the alkaline milk in order to avoid coagulation due to a local pH drop.

The neutralized milk obtained in the second step is not yet completely coagulated. Coagulation is completed in a third step in which the neutralized milk is subjected to dielectric heating treatment using microwaves. In the heat treatment in the third step, external heating using a tank etc. causes local overheating, and a large amount of carbon dioxide is generated locally, and convection is obstructed by the formed solidified matter, so heat is not transmitted uniformly. , you can only get extremely uneven cards. In contrast, when an internal heating method using dielectric heating is employed, the heating is less uneven and the above-mentioned drawbacks do not occur. That is, when dielectrically heated, the entire curd is heated uniformly, and carbon dioxide gas generated from the carbonate contained in the curd becomes microbubbles, resulting in a homogeneous, smooth, and finely textured curd.

Although the effect of carbon dioxide gas is not necessarily clear, it is thought to have the effect of sealing the amino groups of milk proteins such as casein and aiding coagulation. Therefore, the presence of microbubbles of carbon dioxide gas uniformly throughout the coagulation at the start of coagulation is considered to be an important factor for uniform and smooth coagulation of milk.

By being able to coagulate smoothly in this way, it is possible to secure useful proteins and to take in a large amount of vitamins, making it possible to produce curd rich in nutrients. On the other hand, rapid coagulation caused by the acid addition method causes denaturation of some proteins and destruction of vitamins.

The dielectric heating in the third step is usually 1 g per 1 g of neutralized milk.
~1.5KW, preferably 1~1.3KW (7) It is sufficient to carry out the process for 2.5~3.5 minutes, preferably about 3 minutes. The temperature of the coagulated milk at that time is usually 58 to 60°C.

The time required to complete the first to third steps is usually 0.5 to 1 hour, which is significantly shorter than the lactic acid fermentation method.

The milk curd thus obtained has the same smoothness and fine texture as the curd obtained by the enzymatic method using rennet, and is of high quality. Furthermore, the curd contains large amounts of milk protein, milk fat, and vitamins, and is also supplemented with minerals, making it highly nutritious. In addition, since the pH at the time of coagulation is 5.7 or higher, there is no sour taste as in the acid addition method or lactic acid fermentation method, and the milk odor typified by diacetyl and butyric acid is retained. Furthermore, the emulsifying power of the curd has been enhanced,
As much as about 6 g of triglycerides can be emulsified per Ig of casein in the curd. This shows that it is possible to provide products with excellent taste, and it is also easy to cream, making it possible to use it in cream cheese, creaming powder, etc.

In the present invention, additives such as fats, carbohydrates, and polysaccharide thickeners (eg, alginic acid, starch) may be added as appropriate, as long as they do not affect the above-mentioned effects.

Next, the preparation method of the present invention will be specifically explained based on Examples, but the present invention is not limited only to these Examples.

Example 1 (Preparation of alkaline aqueous solution) 40 g of potassium carbonate was dissolved in 1j7 of water, and the concentration was 4% (p
An aqueous solution of potassium carbonate was obtained.

(Preparation of acetic acid buffer) Dissolve 6 g of sodium acetate, 7 g of calcium acetate, and 3 g of magnesium acetate in 1 g of water, then add acetic acid to p.
Adjusted to H4.2.

(Preparation of milk curd) Fresh milk IN (Sodium content: 5tsgs, calcium content: 6mg, magnesium content: 3rng.

Non-fat milk solids content = 8%) is 3f! Add the above potassium carbonate aqueous solution to the flask at room temperature and adjust the pH to 7.
．． 5 to obtain alkaline milk.

The acetate buffer solution was added little by little to this alkaline milk while stirring to obtain neutralized milk with a pH of 5.8. The amount of buffer added was 0.1847. At this point, the neutralized milk was in an uncoagulated state.

The resulting neutralized milk was placed in a microwave oven and dielectrically heated using microwaves at an output of I Kw per gram of neutralized milk for 3 minutes, and the neutralized milk coagulated.

The resulting curd was smooth and fine-grained, and retained the milky odor of the raw material.

In addition, when the mineral content in the curd was analyzed, the sodium, calcium, and magnesium contents were each 1.
The doses increased to 8 mg, 18 mg, and 15 mg.

Example 2 Milk curd was prepared in the same manner as in Example 1, except that the acetate buffer used in Example 1 was replaced with a buffer having the same composition.

(Preparation of acetic acid buffer) Acetic acid was added to an aqueous solution of 50 g of sodium carbonate, 80 g of calcium carbonate, and 30 g of magnesium carbonate dissolved in 1 g of water to adjust the pH to 4.1, and then boiled for 5 minutes to release carbon dioxide gas. Ta.

The milk curd obtained in this example was of the same quality as in Example 1, and had a fresh milk odor.

Furthermore, when the mineral content of this curd was analyzed, it was found that the sodium content was 118 mg, the calcium content was 18 mg, and the magnesium content was 17 mg.

Example 3 Milk curd was obtained in the same manner as in Example 1 except that an acetate buffer was added so that the pH of the neutralized milk became the value shown in Table 1.

Table 1 shows the properties of the obtained card.

Comparative Examples 1 and 2 Milk curds were prepared in the same manner as in Example 1, except that an acetate buffer was added so that the pH of the neutralized milk became the value shown in Table 1.

The results are shown in Table 1.

[Margin below]

Table 1 As is clear from Table 1, by making the neutralized milk weakly acidic, particularly excellent high quality milk curd can be obtained.

〔Effect of the invention〕

According to the method for preparing dairy curd of the present invention, high-quality dairy curd with smoothness, fine texture, and fresh milk odor comparable to that of the enzymatic method using rennet can be produced at low cost and in a short time. In addition to being able to absorb moisture and replenish minerals, it can also enhance emulsifying power. As a result, it is possible to provide a dairy curd that is of high quality and rich in nutrients, and can also be used for new uses such as cream.

Patent applicant: Ikirun Co., Ltd.

Claims (1)

[Claims] 1 Milk is made into weakly alkaline alkaline milk, and an acetic acidic buffer containing an acetate and/or carbonate of an alkali metal and/or an alkaline earth metal is added to the alkaline milk. 1. A method for preparing dairy curd, which comprises preparing weakly acidic neutralized milk, and then subjecting the neutralized milk to dielectric heat treatment. 2. The preparation method according to claim 1, wherein the alkaline milk has a pH of 7.3 to 7.5 or less. 3. The preparation method according to claim 1, wherein alkaline milk is prepared by adding an aqueous potassium carbonate solution. 4. The preparation method according to claim 1, wherein the acetate buffer has a pH of 4.0 to 4.2. 5. The preparation method according to claim 1, wherein the alkali metal or alkaline earth metal acetate is sodium acetate, calcium acetate or magnesium acetate. 6 The concentration of sodium acetate, calcium acetate and magnesium acetate in the acetate buffer is 5 to 6% by weight, respectively,
6-7% by weight and 2-3% by weight. 7. The preparation method according to claim 1, wherein the neutralized milk has a pH of 5.7 to 5.85. 8. The preparation method according to claim 1, wherein the milk is an aqueous liquid of animal milk or skimmed or whole-fat milk powder.