阅读说明：本技术 常温活性牛奶及其制备方法 (Normal temperature active milk and preparation method thereof ) 是由 卢晓莉 耿云惠 刘丽 郭慧 李兴 李聚泽 刘敏轩 王佳豪 刘龙女 解晓彤 于 2021-07-21 设计创作，主要内容包括：本发明公开了一种常温活性牛奶,制备它的原料为原料乳；本发明还公开了它的制备方法,是采用直接蒸汽灭菌的方式实现灭菌的目的,通过缩短杀菌时间,有效地降低牛奶中乳球蛋白、乳铁蛋白等蛋白质的变性率,减少营养物质的损失,同时还能够提升牛奶的口感。本发明适用于制备常温活性牛奶。(The invention discloses normal-temperature active milk, which is prepared by taking raw materials as raw milk; the invention also discloses a preparation method thereof, which realizes the purpose of sterilization by adopting a direct steam sterilization mode, effectively reduces the denaturation rate of proteins such as lactoglobulin, lactoferrin and the like in the milk by shortening the sterilization time, reduces the loss of nutrient substances, and can improve the mouthfeel of the milk. The invention is suitable for preparing normal temperature active milk.)

1. A preparation method of normal-temperature active milk is characterized by comprising the following steps: and (3) taking the raw milk, and sequentially carrying out pasteurization, concentration treatment, sterilization and cooling on the raw milk to obtain the normal-temperature active milk.

2. The method for preparing normal temperature active milk according to claim 1, wherein the raw milk is raw milk or concentrated milk, and the raw milk has a protein content of 3.3-4.5% and a fat content of 3.8-5.0%.

3. The method for preparing normal temperature active milk according to claim 1, wherein the raw milk is sequentially filtered, purified and homogenized before being pasteurized, the homogenizing temperature is 60-80 ℃, and the pressure is 100-200 bar.

4. The method for preparing room temperature active milk according to claim 1, wherein the pasteurization temperature is 75-85 ℃ and the time is 10-20 s.

5. The method for preparing normal temperature active milk according to any one of claims 1 to 4, wherein the concentration treatment is performed by an RO membrane filtration concentration method at 2-6 ℃.

6. The method for preparing normal temperature active milk according to any one of claims 1 to 4, wherein the sterilization is steam immersion sterilization or steam injection sterilization.

7. The method for preparing normal temperature active milk according to claim 6, wherein the temperature of the steam immersion sterilization and the steam injection sterilization is 140-155 ℃ for 0.5-2 s.

8. A method for preparing normal temperature active milk according to claim 1, 2, 3, 4 or 7, wherein the cooling is instantaneous degassing cooling method, the cooling time is 0.5-5s, and the temperature after cooling is 15-30 ℃.

9. Normal-temperature active milk, characterized in that the normal-temperature active milk is prepared by the preparation method of the normal-temperature active milk according to any one of claims 1 to 8, and the shelf life of the normal-temperature active milk is 2 to 5 months.

Technical Field

The invention belongs to the technical field of dairy product processing, and relates to milk, in particular to normal-temperature active milk and a preparation method thereof.

Background

As is well known, milk is gradually an ideal natural nutritional food for human beings due to the fact that the milk contains rich nutritional elements, is essential in modern family life, and as the living standard of people is continuously improved, more people begin to pay attention to the flavor and the nutritional value of the milk. The common sterilization milk in the market at present is divided into two sterilization modes of pasteurization and ultrahigh temperature instant sterilization. The milk stored at normal temperature is mostly produced by an ultrahigh temperature instant sterilization process.

Pasteurization is carried out by heating the emulsion to 62-65 deg.C for 30 min. The sterilization mode has fresh mouthfeel, but the sterilization by the method can kill various growth pathogenic bacteria in the emulsion generally, but can not kill partial thermophilic bacteria, heat-resistant bacteria, spores and the like easily. Therefore, the quality guarantee period of the pasteurized milk is 3-15 days, the market is generally 7 days, and the storage temperature must be lower than 8 ℃.

The ultrahigh-temperature instant sterilization treatment is divided into two stages, wherein the first stage is to preheat the emulsion to about 75 ℃; the second stage needs to continue heating the emulsion to 140 ℃ at 136 ℃ for 4-6s, and then rapidly cooling the emulsion to room temperature. Although the emulsion can kill all bacteria and heat-resistant spores by ultrahigh-temperature instant sterilization treatment, and can be stored at normal temperature for 3-6 months, after the sterilization treatment by the method, because the sterilization time is long, the protein in the emulsion is easy to denaturize and gelatinize, not only can a large amount of nutrient be lost, but also the taste of the product is poor because the content of the furosine is greatly increased.

The two sterilization modes have advantages and disadvantages, the shelf life of the milk is prolonged by ultrahigh-temperature instant sterilization treatment, but the milk is sterilized at 136-140 ℃ for 3-5s, the taste changes to a certain extent, the loss of nutrients is more, the pasteurization process is incomplete in sterilization, spores in the product cannot be killed, the shelf life of the product can be only stored at low temperature for 3-15 days, and the market is generally 7 days.

Therefore, the research of the milk which can not only reserve the nutrient substances in the milk to a greater extent, but also can prolong the shelf life is particularly important.

Disclosure of Invention

The invention aims to provide the normal-temperature active milk, which further improves the nutritive value and the taste of the product;

the invention also aims to provide a preparation method of the normal-temperature active milk, which is simple and convenient, can reduce the loss of nutrient substances in the milk, ensure the taste of the milk and prolong the quality guarantee period of the milk.

In order to achieve the purpose, the invention adopts the technical scheme that:

a preparation method of normal-temperature active milk comprises the following steps: and (3) taking the raw milk, and sequentially carrying out pasteurization, concentration treatment, sterilization and cooling on the raw milk to obtain the normal-temperature active milk.

As a limitation, the raw milk is raw milk or concentrated milk, and the protein content in the raw milk is 3.3-4.5%, and the fat content in the raw milk is 3.8-5.0%.

As another limitation, the raw milk is sequentially filtered, cleaned and homogenized before being pasteurized, wherein the homogenization temperature is 60-80 ℃, and the pressure is 100-200 bar.

As a third limitation, the pasteurization temperature is 75-85 ℃ and the time is 10-20 s.

As a fourth limitation, the concentration treatment is carried out by adopting an RO membrane filtration concentration method at the temperature of 2-6 ℃.

As a fifth limitation, the sterilization employs steam immersion sterilization or steam injection sterilization.

As a further limitation, the temperature of the steam immersion sterilization and the steam injection sterilization is 140-155 ℃, and the time is 0.5-2 s.

As a sixth limitation, the cooling is carried out by an instantaneous degassing cooling method, the cooling time is 0.5-5s, and the temperature after cooling is 15-30 ℃.

The invention also provides the normal-temperature active milk prepared by the preparation method, and the shelf life of the normal-temperature active milk is 2-5 months.

Due to the adoption of the technical scheme, compared with the prior art, the invention has the technical progress that:

firstly, the preparation method of the normal-temperature active milk provided by the invention adopts a steam immersion type or steam jet type sterilization mode, shortens the sterilization time to 0.5-2s, reduces the denaturation rate of proteins such as lactoglobulin and lactoferrin in the milk, reduces the loss of nutrient substances in the milk, and simultaneously improves the taste of the milk;

secondly, the preparation method of the normal-temperature active milk combines direct steam sterilization and RO membrane concentration treatment, further reduces the denaturation rate of protein in the milk, improves the content of the protein in the milk, and effectively prolongs the shelf life of the milk.

The invention is suitable for preparing normal temperature active milk.

Detailed Description

The present invention is further illustrated by the following specific examples, which are to be construed as merely illustrative, and not limitative of the remainder of the disclosure.

Example 1 preparation method of normal temperature active milk

The embodiment comprises the following steps which are carried out in sequence:

s1, taking 80kg of raw milk, filtering, purifying the milk, homogenizing under the conditions of 180bar and 70 ℃, and pasteurizing at 75 ℃ for 20s to obtain a liquid material A;

s2, cooling the liquid material A to 6 ℃, and concentrating by an RO (reverse osmosis) membrane to obtain concentrated milk B with the fat content of 3.9% and the protein content of 3.3%;

s3, performing steam immersion sterilization on the concentrated milk B at 155 ℃ for 0.5s to obtain a liquid material C;

s4, carrying out sterile homogenization on the liquid material C under the condition of 200bar, and cooling to 25 ℃ to obtain the normal-temperature active milk.

Example 2-6 preparation of Normal temperature active milk

Examples 2 to 6 are methods for preparing normal temperature active milk, and the steps are substantially the same as those in example 1, except for the differences in the amounts of raw materials and process parameters, as detailed in table 1:

TABLE 1 summary of the process parameters of examples 2-6