CN111011490A

CN111011490A - Sterile milk and preparation method thereof

Info

Publication number: CN111011490A
Application number: CN201911378956.4A
Authority: CN
Inventors: 王磊; 莫蓓红; 刘振民; 徐致远
Original assignee: Bright Dairy and Food Co Ltd
Current assignee: Bright Dairy and Food Co Ltd
Priority date: 2019-12-27
Filing date: 2019-12-27
Publication date: 2020-04-17

Abstract

The invention discloses a preparation method of sterile milk, which selects the total number of colonies to be less than or equal to 10⁵cfu/mL raw milk the following steps were performed: (1) preheating raw milk to 65-85 ℃; (2) homogenizing the raw material emulsion obtained in the step (1) at ultrahigh pressure to obtain sterilized raw material emulsion; wherein the homogenizing pressure of the ultrahigh-pressure homogenizing is 250-400 MPa, and the homogenizing temperature is 65-85 ℃; (3) and (3) cooling the sterilized raw milk obtained in the step (2) to 4-8 ℃, and filling into aseptic packages to obtain aseptic milk products. The invention has the advantages that the traditional homogenizing heat sterilization distribution method is completely replaced by screening raw milk and adopting an ultrahigh pressure homogenizing process, the process operation flow is simplified, the active ingredients and the flavor in the milk are retained to the maximum extent due to the fact that the product in the equipment is damaged by dynamic high pressure and instant (< 1s) heat, and meanwhile, the quality guarantee period can be prolonged to 5 months to the maximum.

Description

Sterile milk and preparation method thereof

Technical Field

The invention relates to the technical field of dairy product processing, in particular to sterile milk and a preparation method thereof.

Background

The fresh milk is relatively low in thermal damage, so that more nutrition is reserved, but the problems that the product has short shelf life and is difficult to transport in a large range are also caused. In contrast, the normal-temperature product has a long shelf life due to large damage caused by ultra-high-temperature sterilization heat and loss of a large amount of nutrition, but reaches a commercial sterile state, is suitable for large-scale transportation, and has wide market popularization rate. Thus, the reservation of more nutrition on a shelf life extension basis has been the prime for the problem to be solved.

Disclosure of Invention

In order to solve the problems, the invention aims to disclose sterile milk and a preparation method thereof, the method optimizes sterilization parameters and simplifies process flow by screening raw milk and changing a homogeneous sterilization mode, the obtained product reaches a commercial sterile state in a shelf life, the content of nutrient substances reaches the level of pasteurized milk, and the shelf life is greatly prolonged.

The invention is realized by the following technical scheme:

specifically, on the one hand, the preparation method of the sterile milk is provided, and the total number of selected colonies is less than or equal to 10⁵cfu/mL raw milk the following steps were performed:

(1) preheating raw milk to 65-85 ℃;

(2) homogenizing the raw material emulsion obtained in the step (1) at ultrahigh pressure to obtain sterilized raw material emulsion; wherein the homogenizing pressure of the ultrahigh-pressure homogenizing is 250-400 MPa, and the homogenizing temperature is 65-85 ℃;

(3) and (3) cooling the sterilized raw milk obtained in the step (2) to 4-8 ℃, and filling into aseptic packages to obtain aseptic milk products.

Through the technical scheme, the raw milk is screened, the homogenizing sterilization mode is changed, the sterilization parameters are optimized, the process flow is simplified, the obtained product reaches a commercial sterile state in the shelf life, the content of nutrient substances reaches the level of pasteurized milk, and the shelf life is greatly prolonged.

Specifically, in step (1), the total number of colonies is preferably 1 ten thousand to 5 ten thousand cfu/mL, and most preferably 1 ten thousand to 3 ten thousand cfu/mL. The preheating temperature is preferably 75-85 ℃, and most preferably 80-85 ℃;

in the step (2), the homogenizing pressure of the ultra-high pressure homogenization is preferably 300 to 400MPa, and most preferably 350 to 400 MPa. The homogenization temperature is 65 to 85 ℃, preferably 75 to 85 ℃, and most preferably 80 to 85 ℃.

Further, in the step (1), the raw milk is one or more of whole milk and reduced milk.

Further, in the step (3), the aseptic package is an aseptic package such as a tetra Pak brick, a tetra Pak pillow, a tetra Pak, an aseptic bag, a Karme bag and the like.

On the other hand, the invention also provides sterile milk which is directly prepared from the sterile milk and the preparation method thereof.

Compared with the prior art, the invention has the following advantages: the raw milk is screened, an ultrahigh pressure homogenization process is adopted, the traditional homogenization heat sterilization distribution method is completely replaced, the process operation flow is simplified, the product is damaged by dynamic high pressure and instant (< 1s) heat in equipment, the active ingredients and the flavor in the milk are retained to the maximum extent, and meanwhile, the longest quality guarantee period can be up to 5 months.

Detailed Description

The invention is further illustrated by the following examples, which are not intended to limit the scope of the invention. The experimental methods without specifying specific conditions in the following examples were selected according to the conventional methods and conditions, or according to the commercial instructions.

The starting materials in the following examples were all commercially available unless otherwise specified.

The sources of the raw materials of the following examples are:

raw milk: guangming Dairy industries, Inc.

Example 1

A method for preparing sterile milk comprises selecting 10 total bacterial colonies⁵cfu/mL raw milk the following steps were performed:

(1) preheating raw milk to 65 ℃;

(2) homogenizing the raw material emulsion obtained in the step (1) at ultrahigh pressure to obtain sterilized raw material emulsion; wherein the homogenizing pressure of the ultrahigh-pressure homogenizing is 250MPa, and the homogenizing temperature is 65 ℃;

(3) and (3) cooling the sterilized raw milk obtained in the step (2) to 4 ℃, and filling into aseptic packages to obtain the aseptic milk product.

Example 2

A method for preparing sterile milk comprises selecting total bacterial count of 8X10⁴cfu/mL raw milk the following steps were performed:

(1) preheating raw milk to 75 ℃;

(2) homogenizing the raw material emulsion obtained in the step (1) at ultrahigh pressure to obtain sterilized raw material emulsion; wherein the homogenizing pressure of the ultrahigh-pressure homogenizing is 300MPa, and the homogenizing temperature is 85 ℃;

(3) and (3) cooling the sterilized raw milk obtained in the step (2) to 5 ℃, and filling into aseptic packages to obtain the aseptic milk product.

Example 3

(1) preheating raw milk to 85 ℃;

(2) homogenizing the raw material emulsion obtained in the step (1) at ultrahigh pressure to obtain sterilized raw material emulsion; wherein the homogenizing pressure of the ultrahigh-pressure homogenizing is 400MPa, and the homogenizing temperature is 85 ℃;

(3) and (3) cooling the sterilized raw milk obtained in the step (2) to 6 ℃, and filling into aseptic packages to obtain the aseptic milk product.

Example 4

A method for preparing sterile milk comprises selecting total bacterial count of 2X10⁴cfu/mL raw milk the following steps were performed:

(1) preheating raw milk to 80 ℃;

(2) homogenizing the raw material emulsion obtained in the step (1) at ultrahigh pressure to obtain sterilized raw material emulsion; wherein the homogenizing pressure of the ultrahigh-pressure homogenizing is 350MPa, and the homogenizing temperature is 80 ℃;

Example 5

A method for preparing sterile milk comprises selecting total colony number of 3X10⁴cfu/mL raw milk the following steps were performed:

(1) preheating raw milk to 70 ℃;

(2) homogenizing the raw material emulsion obtained in the step (1) at ultrahigh pressure to obtain sterilized raw material emulsion; wherein the homogenizing pressure of the ultrahigh-pressure homogenizing is 300MPa, and the homogenizing temperature is 70 ℃;

(3) and (3) cooling the sterilized raw milk obtained in the step (2) to 8 ℃, and filling into aseptic packages to obtain the aseptic milk product.

Example 6

A method for preparing sterile milk comprises selecting total bacterial count of 1X10⁴cfu/mL raw milk the following steps were performed:

(1) preheating raw milk to 85 ℃;

Comparative example 1

The preparation method of the comparative example is the same as that of example 1, except that the ultrahigh pressure homogenization is changed into the traditional homogenization heat sterilization, wherein the homogenization pressure temperature is 20MPa and 60 ℃, and the sterilization temperature is 85 ℃ and 15 s.

Comparative example 2

The comparative example was prepared in the same manner as example 1, except that the ultrahigh pressure treatment was carried out at a pressure of 300 MPa.

Comparative example 3

The comparative example was prepared in the same manner as example 1 except that UHT sterilization was performed under the sterilization conditions of 137 ℃ for 4 seconds.

Effect example 1

The prepared milk samples are subjected to microbiological detection according to reference standards GB 4789.2, GB 4789.3, 4789.15, GB4789.4 and GB 4789.10. The sample was allowed to stand for 7 days at a temperature of 25 ℃ for 150 days, whereas the standing temperature of comparative example 1 was 4 ℃. The results are shown in tables 1 and 2.

TABLE 1 microbial results of each example and comparative example after 7 days of standing

Note: ND represents no detection, and each index item has a unit of CFU/mL

TABLE 2 microbial results of each example and comparative example after 150 days

Note: ND represents no detection, and each index item has a unit of CFU/mL

As shown in the results of tables 1 and 2, examples and comparative example 1 illustrate that the same sterilization effect can be achieved using ultra-high pressure homogenization and conventional pasteurization; commercial sterility can be maintained at about 5 months, whereas conventional static ultra-high pressures are difficult to guarantee.

Effect example 2

The lactoferrin, β -lactoglobulin content was determined for each of the examples and comparative examples the results are shown in Table 2.

TABLE 3

As can be seen from table 2, the ultra-high pressure homogenization is similar to the conventional pasteurized milk in nutrition retention, and the method can retain more active nutrients compared with UHT.

Effect example 3

20 persons were selected to perform sensory evaluation on the samples of each example and comparative example on day 3, and the freshness of mastic was scored, 5 points being full, and the average scores recorded are shown in table 4.

TABLE 4

	Boswellia freshness score
		Example 1	4.9
Example 2	4.9
		Example 3	3.9
Example 4	4.0
		Example 5	4.8
Example 6	4.3
		Comparative example 1	4.0
Comparative example 2	5.0
		Comparative example 3	2.1

As can be seen from the above table, the ultra-high pressure homogenization is also close to or even superior to pasteurized milk in terms of freshness.

The above-described embodiments are merely illustrative of one or more embodiments of the present invention, which are described in more detail and detail, but are not to be construed as limiting the scope of the invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention.

Claims

1. A method for preparing aseptic milk is characterized in that the total number of selected bacterial colonies is less than or equal to 10⁵cfu/mL raw milk the following steps were performed:

(1) preheating raw milk to 65-85 ℃;

2. The method for preparing aseptic milk according to claim 1, wherein in step (1), the raw milk is one or more of whole milk and reduced milk.

3. The method for preparing aseptic milk according to claim 1, wherein in step (3), the aseptic package is an aseptic package such as a tetra Pak, aseptic pouch, and Karme bag.

4. An aseptic milk directly obtained by the method for producing an aseptic milk according to any one of claims 1 to 3.