阅读说明：本技术 一种零乳糖酸牛奶及其制备方法 (Zero-lactose yoghurt and preparation method thereof ) 是由 崔树勇 李亚杰 尹玉庆 于 2020-04-27 设计创作，主要内容包括：本发明公开了一种零乳糖酸牛奶及其制备方法,所述方法包括以下步骤：S1、将经检验合格的生牛乳置于贮奶罐中,备用；S2、生牛乳经过95℃巴氏杀菌300秒,随后降温至42±1℃,得到杀菌后的牛乳；S3、在步骤S2所得的牛乳中添加β-半乳糖苷酶,添加量0.02％-0.05％；再添加乳酸菌菌种0.001％-0.003％,搅拌使其溶解并分布均匀；S4、在42±1℃条件下保存4-8小时；S5、取样检测、灌装、即得零乳糖酸牛奶成品。本方法可以使生牛乳中的乳糖完全水解,达到国标要求的小于0.5％,即零乳糖水平。(The invention discloses a lactose-free yoghurt and a preparation method thereof, wherein the method comprises the following steps: s1, placing the qualified raw milk in a milk storage tank for later use; s2, pasteurizing the raw milk at 95 ℃ for 300 seconds, and then cooling to 42 +/-1 ℃ to obtain the sterilized milk; s3, adding beta-galactosidase in the milk obtained in the step S2, wherein the addition amount is 0.02% -0.05%; then adding 0.001% -0.003% of lactobacillus strain, stirring to dissolve and distribute uniformly; s4, preserving for 4-8 hours at the temperature of 42 +/-1 ℃; and S5, sampling, detecting and filling to obtain the finished product of the lactose-free yoghurt. The method can completely hydrolyze the lactose in the raw milk to reach the national standard requirement of less than 0.5 percent, namely the lactose-free level.)

1. A method for preparing lactose-free yoghurt is characterized by comprising the following steps:

s1, placing the qualified raw milk in a milk storage tank for later use;

s2, pasteurizing the raw milk at 95 ℃ for 300 seconds, and then cooling to 42 +/-1 ℃ to obtain the sterilized milk;

s3, adding beta-galactosidase in the milk obtained in the step S2, wherein the addition amount is 0.02% -0.05%; then adding 0.001% -0.003% of lactobacillus strain, stirring to dissolve and distribute uniformly;

s4, preserving for 4-8 hours at the temperature of 42 +/-1 ℃;

and S5, sampling, detecting and filling to obtain the finished product of the lactose-free yoghurt.

2. The lactose-free yoghurt produced by the process of claim 1.

Technical Field

The invention relates to the field of dairy product processing, in particular to lactose-free yoghurt and a preparation method thereof.

Background

Lactose is a carbohydrate peculiar to human and mammal milk, and as taught by the Chinese resident dietary guidelines, lactose in milk cannot be completely decomposed and absorbed by the small intestine due to the lack of lactase, and lactose intolerance is caused by the fact that the residual lactose enters the colon and cannot be fermented and utilized in the colon.

Raw milk naturally contains 4-6% of lactose, the prior art utilizes the decomposition of the lactose by lactic acid bacteria to prepare low-lactose pasteurized milk, the lactose hydrolysis process is simple, and the lactose hydrolysis degree is not high enough.

Disclosure of Invention

Aiming at the technical defects, the invention aims to provide the lactose-free yoghurt with high lactose hydrolysis degree and the preparation method thereof, aiming at solving the problems in the background art.

In order to solve the technical problems, the invention adopts the following technical scheme:

the invention provides a preparation method of lactose-free yoghurt, which comprises the following steps:

s1, placing the qualified raw milk in a milk storage tank for later use;

s2, pasteurizing the raw milk at 95 ℃ for 300 seconds, and then cooling to 42 +/-1 ℃ to obtain the sterilized milk;

s3, adding beta-galactosidase in the milk obtained in the step S2, wherein the addition amount is 0.02% -0.05%; then adding 0.001% -0.003% of lactobacillus strain, stirring to dissolve and distribute uniformly;

s4, preserving for 4-8 hours at the temperature of 42 +/-1 ℃;

and S5, sampling, detecting and filling to obtain the finished product of the lactose-free yoghurt.

In the experiment for preparing the lactose-free yoghurt by using the method, the inventor finds that beta-galactosidase hydrolyzes lactose in the cow milk in 0-3 hours at the early stage, and the hydrolysis rate is 80-95%; and in the later period of 3-6 hours, the lactic acid bacteria begin to ferment and metabolize the residual lactose, when the pH value of the milk is reduced to about 5.5, the beta-galactosidase loses activity, the residual lactose in the milk is utilized by the fermentation and the metabolism of the lactic acid bacteria, and the lactose is basically metabolized after the fermentation is finished. Sampling detection shows that the lactose hydrolysis rate is more than 99.5 percent, the lactose residual quantity is less than 0.5 percent, and the requirement of national standard for zero lactose is met.

The invention also provides the lactose-free yoghurt prepared by the preparation method.

The invention has the beneficial effects that: the method can completely hydrolyze the lactose in the raw milk to reach the national standard requirement of less than 0.5 percent, namely the lactose-free level.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.

FIG. 1 is a graph showing the hydrolysis of lactose in cow's milk by lactase at 42 ℃.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Example 1

A method for preparing lactose-free yoghurt comprises the following steps:

s1, placing the qualified raw milk in a milk storage tank for later use;

s2, pasteurizing the raw milk at 95 ℃ for 300 seconds, and then cooling to 42 +/-1 ℃ to obtain the sterilized milk;

s3, adding beta-galactosidase in the milk obtained in the step S2, wherein the addition amount is 0.05%; then adding 0.003% of lactobacillus strain, stirring to dissolve and distribute uniformly;

s4, the lactase has higher hydrolysis efficiency to lactose in milk when being stored for 4 hours at the temperature of 42 +/-1 ℃ (see figure 1);

and S5, sampling, detecting and filling to obtain the finished product of the lactose-free yoghurt.

Example 2

A method for preparing lactose-free yoghurt comprises the following steps:

s1, placing the qualified raw milk in a milk storage tank for later use;

s2, pasteurizing the raw milk at 95 ℃ for 300 seconds, and then cooling to 42 +/-1 ℃ to obtain the sterilized milk;

s3, adding beta-galactosidase in the milk obtained in the step S2, wherein the addition amount is 0.03%; then adding 0.002% of lactobacillus strain, stirring to dissolve and distribute uniformly;

s4, preserving for 6 hours at the temperature of 42 +/-1 ℃;

preferably, the temperature of the raw milk in step S1 is 6 ± 1 ℃.

Example 3

A method for preparing lactose-free yoghurt comprises the following steps:

s1, placing the qualified raw milk in a milk storage tank for later use;

s2, pasteurizing the raw milk at 95 ℃ for 300 seconds, and then cooling to 42 +/-1 ℃ to obtain the sterilized milk;

s3, adding beta-galactosidase in the milk obtained in the step S2, wherein the addition amount is 0.02%; then adding 0.001% of lactobacillus strain, stirring to dissolve and distribute uniformly;

s4, storing for 8 hours at the temperature of 42 +/-1 ℃;

and S5, sampling, detecting and filling to obtain the finished product of the lactose-free yoghurt.

It will be apparent to those skilled in the art that various changes and modifications may be made in the present invention without departing from the spirit and scope of the invention. Thus, if such modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include such modifications and variations.