阅读说明：本技术 一种低温巴氏奶及其制备方法 (Low-temperature pasteurized milk and preparation method thereof ) 是由 李伟 王彦平 孟蝶 巴根纳 于 2019-11-29 设计创作，主要内容包括：本发明提供了一种低温巴氏奶及其制备方法。该制备方法包括对牛奶进行离心除菌和直接杀菌的步骤；其中,所述直接杀菌采用蒸汽浸入式杀菌或者蒸汽喷射式杀菌的方式进行,杀菌温度为121-130℃,时间为4-6s。本发明还提供了上述方法制备的低温巴氏奶。通过采用本发明的技术方案,能够使低温巴氏奶的货架期达到3个月,并且能够使低温巴氏奶的营养和口感接近低温巴氏奶,营养、口感和风味远远超过UHT灭菌乳。(The invention provides low-temperature pasteurized milk and a preparation method thereof. The preparation method comprises the steps of performing centrifugal sterilization and direct sterilization on milk; wherein, the direct sterilization is carried out by adopting a steam immersion sterilization or steam injection sterilization mode, the sterilization temperature is 121-130 ℃, and the time is 4-6 s. The invention also provides the low-temperature pasteurized milk prepared by the method. By adopting the technical scheme of the invention, the shelf life of the low-temperature pasteurized milk can reach 3 months, the nutrition and the taste of the low-temperature pasteurized milk are close to those of the low-temperature pasteurized milk, and the nutrition, the taste and the flavor of the low-temperature pasteurized milk are far more than those of UHT sterilized milk.)

1. A method for preparing low-temperature pasteurized milk, it includes carrying on the steps of centrifugal sterilization and direct sterilization to the milk;

wherein, the direct sterilization is carried out by adopting a steam immersion sterilization or steam injection sterilization mode, the sterilization temperature is 121-130 ℃, and the time is 4-6 s.

2. The method according to claim 1, wherein the centrifugal sterilization is performed by a centrifugal sterilizer at 4500-5000 rpm.

3. The method of claim 1 or 2, wherein the method comprises the steps of filtering, preheating, removing impurities, centrifuging, sterilizing, concentrating, degassing, directly sterilizing, evaporating for cooling, homogenizing, cooling, aseptic filling, aseptic packaging, and refrigerating fresh milk.

4. The preparation method according to claim 3, wherein the fresh milk is obtained by rapidly cooling freshly squeezed milk to below 4 ℃; preferably, the flash is cooled to 1-4 ℃ in 2 hours.

5. The preparation method as claimed in claim 3, wherein the impurity removal is performed by a milk purifier at 5000-6000 rpm.

6. The production method according to claim 3, wherein the concentration is performed by means of flash evaporation.

7. The method of claim 3, wherein the degassing temperature is 60-70 ℃ and the vacuum degree is-0.6 bar to-0.7 bar.

8. The preparation method as claimed in claim 3, wherein the homogenization is performed in a two-stage homogenization mode, the pressure of the one-stage homogenization is 40-50bar, and the pressure of the two-stage homogenization is 200-250 bar.

9. The method according to any one of claims 1 to 8, wherein the method comprises the following specific steps:

1) and (3) filtering: rapidly cooling the squeezed milk to below 4 deg.C to obtain fresh milk, and filtering with 60-100 mesh filter;

2) preheating: preheating milk to 55-60 ℃;

3) removing impurities: removing impurities from milk by a milk purifier at the rotation speed of 5000-;

4) and (3) centrifugal sterilization: sterilizing milk by a centrifugal sterilization machine at the rotating speed of 4500 and 5000 rpm;

5) concentration: carrying out flash evaporation concentration on milk, and carrying out milk index standardization;

6) degassing: degassing milk at 60-70 deg.C under-0.6 bar to-0.7 bar;

7) direct sterilization: directly sterilizing the milk by adopting a steam immersion sterilization mode or a steam jet sterilization mode at the temperature of 121-;

8) and (3) evaporation and cooling: after sterilization, the milk is evaporated and cooled in vacuum, and steam condensate water formed in the sterilization process is removed, and the milk is cooled to 70-75 ℃ through an interlayer;

9) homogenizing: homogenizing milk by two-stage homogenizing method at 40/200-50/250 bar;

10) and (3) cooling: cooling the milk to 20-30 ℃ to obtain the low-temperature pasteurized milk;

11) filling: sterile filling;

12) packaging: aseptic packaging;

13) and (3) storage: cooling the low temperature pasteurized milk to 1-4 ℃ for storage.

10. A low temperature pasteurized milk prepared by the method of any one of claims 1-9;

wherein, the low-temperature pasteurized milk meets the following index requirements:

Technical Field

The invention relates to low-temperature pasteurized milk and a preparation method thereof, belonging to the technical field of dairy product processing.

Background

At present, domestic low-temperature milk is mainly UHT sterilized milk, and the national standard defines that raw cow (sheep) milk is used as a raw material, reconstituted milk is added or not added, the raw cow (sheep) milk is heated to at least 132 ℃ in a continuous flowing state and is sterilized for a short time, and then the liquid product is prepared by the working procedures of aseptic filling and the like. The shelf life of the sterilized milk at low temperature can reach 6 months. Due to the high heating intensity of the ultra-high temperature sterilized milk, heat-sensitive components in the milk are damaged to a certain extent, and the mouthfeel and nutrition of the milk are different from those of pasteurized milk.

With the demands of consumers on freshness, nutrition and delicacy of milk, a high-temperature short-time sterilization process is adopted, and centrifugal sterilization and aseptic filling and packaging technologies are combined, so that commercial sterility of pasteurized milk is realized at low temperature. The pasteurized milk is prepared by using fresh milk as raw material and pasteurizing at 72-85 deg.C/10-15 s to kill harmful microorganisms. The sterilization method can maintain the nutrition and taste of the fresh milk to the maximum extent. Ultra-high temperature sterilization means that: the sterilization treatment is carried out at the moment of 135 ℃ and 150 ℃/4-15s, so that the microorganisms and spores which can grow in the milk are completely destroyed, and the beneficial and harmful microorganisms in the milk are completely killed to achieve commercial sterility.

The shelf life of the pasteurized milk is short mainly due to the fact that a small amount of bacterial colonies and psychrophiles exist in pasteurized milk, meanwhile, protease and lipase can be generated by the psychrophiles at the temperature of 2-7 ℃, and the shelf life is 14-21 days at most due to the action of the enzyme and microorganisms. The main difference between low-temperature pasteurized milk and ultra-high-temperature pasteurized milk is that pasteurized milk is not aseptically filled; low temperature pasteurized milk cannot be stored and sold at low temperatures, which is not a commercial aseptic product.

Disclosure of Invention

In order to solve the above technical problems, the present invention aims to provide a method for preparing low-temperature pasteurized milk, which can prolong the shelf life of pasteurized milk by adopting centrifugal sterilization and direct sterilization, and simultaneously keep the taste and nutrition of milk as much as possible.

In order to achieve the above objects, the present invention provides a method for preparing low temperature pasteurized milk, which comprises the steps of performing centrifugal sterilization and direct sterilization on milk;

wherein, the direct sterilization is carried out by adopting a steam immersion sterilization or steam injection sterilization mode, the sterilization temperature is 121-130 ℃, and the time is 4-6 s.

According to a specific embodiment of the present invention, the centrifugal sterilization can be performed by using a centrifugal sterilization machine at 4500-.

The method provided by the invention adopts a direct sterilization process of 121-.

According to the specific embodiment of the invention, the preparation method mainly comprises the steps of filtering, preheating, removing impurities, centrifugally sterilizing, concentrating, degassing, directly sterilizing, evaporating and cooling, homogenizing, cooling, aseptically filling, aseptically packaging and refrigerating at the low temperature of 1-4 ℃.

According to a particular embodiment of the invention, the fresh milk is obtained by rapidly cooling freshly expressed milk to below 4 ℃, preferably to 1-4 ℃ within 2 hours, typically starting from 20-30 ℃. The method of the invention can remove foreign matters, impurities, somatic cells, spores and larger bacteria in the fresh milk by rapidly cooling the squeezed milk to below 4 ℃ to obtain the fresh milk, and then removing the foreign matters, impurities, somatic cells, spores and larger bacteria in the fresh milk through the process steps of filtering, impurity removal, sterilization and the like, thereby eliminating the influence of milk microorganisms on the fresh milk.

According to the specific embodiment of the invention, the impurity removal can be carried out by an emulsion purifier, and the rotating speed can be controlled to be 5000-6000 rpm.

According to a particular embodiment of the invention, the concentration may be carried out by means of flash evaporation.

According to a specific embodiment of the present invention, the degassing temperature may be controlled to 60-70 ℃ and the vacuum degree may be controlled to-0.6 bar to-0.7 bar.

According to the specific embodiment of the invention, the homogenization can be carried out in a two-stage homogenization mode, wherein the pressure of the first-stage homogenization is 40-50bar, and the pressure of the second-stage homogenization is 200-250 bar.

According to the specific embodiment of the invention, the cold chain is preferably refrigerated from the milk receiving process to the terminal consumption process, particularly the low-temperature pasteurized milk after packaging is refrigerated at a low temperature of 1-4 ℃, and the cold chain is adopted during the transportation process to ensure the low-temperature refrigeration storage.

According to a specific embodiment of the invention, the preparation method of the low-temperature pasteurized milk provided by the invention comprises the following specific steps:

1) and (3) filtering: rapidly cooling the squeezed milk to below 4 deg.C to obtain fresh milk, and filtering with 60-100 mesh filter;

2) preheating: preheating milk to 55-60 ℃;

3) removing impurities: removing impurities from milk by a milk purifier at the rotation speed of 5000-;

4) and (3) centrifugal sterilization: sterilizing milk by a centrifugal sterilization machine at the rotating speed of 4500 and 5000 rpm;

5) concentration: carrying out flash evaporation concentration on milk, and carrying out milk index standardization;

6) degassing: degassing milk at 60-70 deg.C under-0.6 bar to-0.7 bar;

7) direct sterilization: directly sterilizing the milk by adopting a steam immersion sterilization mode or a steam injection sterilization mode at the temperature of 121-;

8) and (3) evaporation and cooling: after sterilization, the milk is evaporated and cooled in vacuum, and steam condensate water formed in the sterilization process is removed, and the milk is cooled to 70-75 ℃ through an interlayer;

9) homogenizing: homogenizing milk by two-stage homogenizing method at 40/200-50/250 bar;

10) and (3) cooling: cooling the milk to 20-30 deg.C to obtain low temperature pasteurized milk;

11) filling: sterile filling;

12) packaging: aseptic packaging;

13) and (3) refrigerating: cooling the packaged pasteurized milk to 1-4 deg.C for refrigeration.

The invention also provides the low-temperature pasteurized milk prepared by the method. Wherein the low temperature pasteurized milk meets the index requirements shown in the following table 1:

TABLE 1

Index (I)	Numerical range
		Protein, g/100g	≥2.9
Fat, g/100g	≥3.1
		Milk solids not fat, g/100g	≥8.1
The acidity of the water-soluble organic acid,oT	12.0-18.0
		alpha-lactalbumin (undenatured), g/100g	0.05-0.1
Beta-lactoglobulin (undenatured), g/100g	0.1-0.2
		Lactulose, mg/L	40-50
Furfurin, mg/100g protein	30-60

The low-temperature pasteurized milk provided by the invention has the advantages that the sterilization temperature and time are different from those of the low-temperature pasteurized milk, the sterilization technology is added before sterilization, the aseptic filling and packaging technology is adopted, the pollution of the production process is avoided, the time from milking to finishing of production is not more than 12 hours to the maximum extent, the re-pollution of the transportation and production processes is avoided, and the production sanitary condition and an excellent cold chain transportation system are ensured.

80-95% of microorganisms in the milk are removed by adopting centrifugal sterilization and rapid separation, the residual microorganisms in the milk are killed by adopting high-temperature short-time sterilization, the enzymes in the milk are inactivated, and all indexes of the low-temperature pasteurized milk in the shelf life of 3 months meet the pasteurized milk standard.

The low-temperature pasteurized milk provided by the invention has the sterilization process conditions of 121-.

Meanwhile, the low-temperature pasteurized milk of the invention utilizes aseptic filling and packaging technology, avoids pasteurized milk pollution after sterilization, and realizes pasteurized milk low-temperature storage and sale.

By adopting the technical scheme of the invention, the shelf life of the low-temperature pasteurized milk can reach 3 months, the nutrition and the taste of the low-temperature pasteurized milk are superior to those of the pasteurized milk in the current market, and the nutrition, the taste and the flavor of the low-temperature pasteurized milk are far superior to those of UHT sterilized milk.

Detailed Description

The technical solutions of the present invention will be described in detail below in order to clearly understand the technical features, objects, and advantages of the present invention, but the present invention is not limited to the practical scope of the present invention.

Example 1

The embodiment provides a preparation method of low-temperature pasteurized milk, which comprises the following steps:

1) and (3) filtering: the fresh milk was passed through a 60 mesh filter.

2) Preheating: the fresh milk was preheated to 55 ℃.

3) Removing impurities: and (3) removing impurities from the milk by a milk cleaner at the rotating speed of 5000 rpm.

4) And (3) centrifugal sterilization: and (3) sterilizing the fresh milk by a centrifugal sterilizer at the rotating speed of 4500rpm, and separating and removing spores, somatic cells and partial bacterial colonies.

5) Concentration: the indexes are standardized by a flash evaporation system, the vacuum degassing temperature is 60 ℃, and the vacuum degree is-0.6 bar.

6) Direct steam sterilization: the temperature was 121 deg.C/6 s.

7) And (3) evaporation and cooling: and (4) evaporating and cooling the sterilized milk through a vacuum tank, removing steam condensate water in the sterilization process, and simultaneously cooling to 70 ℃.

8) Homogenizing: the pressure was 40/200 bar.

9) And (3) cooling: the temperature was 20 ℃.

10) Filling: and (5) sterile filling.

11) Packaging: and (7) aseptic packaging.

12) Product inspection: and detecting each index.

13) And (3) refrigerating: cooling the pasteurized milk to 1-4 deg.C for refrigeration, and adopting cold chain to ensure low-temperature refrigeration storage during transportation.

The quality test results of the finished low-temperature pasteurized milk are shown in table 2:

TABLE 2

Index (I)	Detecting a value
		Protein, g/100g	3.0
Fat, g/100g	3.4
		Milk solids not fat, g/100g	8.3
The acidity of the water-soluble organic acid,oT	14.0
		alpha-lactalbumin (undenatured), g/100g	0.052
Beta-lactoglobulin (undenatured), g/100g	0.13
		Lactulose, mg/L	45.8
Furfurin, mg/100g protein	43.2
		Shelf life (low temperature), day	90

Example 2

The embodiment provides a preparation method of low-temperature pasteurized milk, which comprises the following steps:

1) and (3) filtering: the fresh milk was passed through an 80 mesh filter.

2) Preheating: the fresh milk was preheated to 58 ℃.

3) Removing impurities: the fresh milk is purified by a milk purifier, and the rotating speed is 5500 rpm.

4) And (3) centrifugal sterilization: and (3) sterilizing the fresh milk by a centrifugal sterilizer at the rotating speed of 4800rpm, and removing spores, somatic cells and partial bacterial colonies.

5) Concentration: standardizing milk indexes by a vacuum flash system, wherein the degassing temperature is 65 ℃, and the vacuum degree is-0.7 bar.

6) Direct steam sterilization: the temperature was 125 deg.C/5 s.

7) And (3) evaporation: and (4) evaporating and cooling the sterilized milk through a vacuum tank, removing steam condensate water in the sterilization process, and simultaneously cooling to 72 ℃.

8) Homogenizing: the pressure was 45/230 bar.

9) And (3) cooling: the temperature was 25 ℃.

10) Filling: and (5) sterile filling.

11) Packaging: and (7) aseptic packaging.

12) Product inspection: and detecting each index.

13) And (3) refrigerating: cooling the pasteurized milk to 1-4 deg.C for refrigeration, and adopting cold chain to ensure low-temperature refrigeration storage during transportation.

The quality test results of the finished low-temperature pasteurized milk are shown in table 3:

TABLE 3

Index (I)	Detecting a value
		Protein, g/100g	3.2
Fat, g/100g	3.5
		Milk solids not fat, g/100g	8.5
The acidity of the water-soluble organic acid,oT	15.0
		alpha-lactalbumin (undenatured), g/100g	0.066
Beta-lactoglobulin (undenatured), g/100g	0.16
		Lactulose, mg/L	46.8
Furfurin, mg/100g protein	48.2
		Shelf life (low temperature), day	90

Example 3

The embodiment provides a preparation method of low-temperature pasteurized milk, which comprises the following steps:

1) and (3) filtering: fresh milk was passed through a 100 mesh filter.

2) Preheating: the fresh milk was preheated to 60 ℃.

3) Removing impurities: the fresh milk is purified by a milk purifier, and the rotating speed is 6000 rpm.

4) And (3) centrifugal sterilization: and (3) sterilizing the fresh milk by a centrifugal sterilizer at the rotating speed of 5000rpm, and removing spores, somatic cells and partial bacterial colonies.

5) Concentration: concentrating by vacuum flash evaporation system to obtain standard milk index, degassing at 70 deg.C and vacuum degree of-0.8 bar.

6) Direct steam sterilization: the temperature was 130 ℃ for 4 s.

7) And (3) evaporation and cooling: and (3) evaporating and cooling the sterilized milk through a vacuum tank, removing steam condensate water in the sterilization process, and simultaneously cooling to 75 ℃.

8) Homogenizing: the pressure was 50/250 bar.

9) And (3) cooling: the temperature was 30 ℃.

10) Filling: and (5) sterile filling.

11) Packaging: aseptic packaging is adopted.

12) Product inspection: and detecting each index.

13) And (3) refrigerating: cooling the pasteurized milk to 1-4 deg.C for refrigeration, and adopting cold chain to ensure low-temperature refrigeration storage during transportation. The quality test results of the finished low-temperature pasteurized milk are shown in table 4:

TABLE 4

Index (I)	Detecting a value
		Protein, g/100g	3.3
Fat, g/100g	3.7
		Milk solids not fat, g/100g	8.8
The acidity of the water-soluble organic acid,oT	16.0
		alpha-lactalbumin (undenatured), g/100g	0.093
Beta-lactoglobulin (undenatured), g/100g	0.19
		Lactulose, mg/L	48.2
Furfurin, mg/100g protein	56.2
		Shelf life (Low temperature)	90

Comparative example 1

The present comparative example provides a method of preparing low temperature pasteurized milk comprising the steps of:

1) and (3) filtering: the fresh milk was passed through an 80 mesh filter.

2) Preheating: the fresh milk was preheated to 55 ℃.

3) Cleaning milk: and (3) removing impurities from the milk by a milk cleaner at the rotating speed of 6000 rpm.

4) Homogenizing: the pressure was 50/250 bar.

5) Concentration: the standardized milk index was concentrated by a vacuum flash system.

6) Pasteurization: the temperature is 72-85 ℃/15 s.

7) And (3) cooling: the temperature was 20 ℃.

8) Filling: and (5) ultra-clean filling.

9) Packaging: and (5) ultra-clean packaging.

10) Product inspection: and detecting each index.

11) And (3) marketing: and (5) after the inspection is qualified, the product is listed.

12) And (3) refrigerating: cooling the pasteurized milk to 1-4 deg.C and refrigerating.

The quality test results of the finished low-temperature pasteurized milk are shown in table 5:

TABLE 5

Index (I)	Detecting a value
		Protein, g/100g	3.2
Fat, g/100g	3.9
		Milk solids not fat, g/100g	8.5
The acidity of the water-soluble organic acid,oT	14.5
		alpha-lactalbumin (undenatured), g/100g	0.16
Beta-lactoglobulin (undenatured), g/100g	0.28
		Lactulose, mg/L	25.6
Furfurin, mg/100g protein	20.2
		Shelf life (low temperature), day	2

Comparative example 2

The present comparative example provides a method of preparing low temperature pasteurized milk comprising the steps of:

1) and (3) filtering: the fresh milk was passed through a 90 mesh filter.

2) Preheating: the fresh milk was preheated to 60 ℃.

3) Cleaning milk: and (3) removing impurities from the milk by a milk cleaner at the rotating speed of 5800 rpm.

4) Homogenizing: the pressure was 50/250 bar.

5) Concentration: the standardized milk index was concentrated by a vacuum flash system.

6) Pasteurization: the temperature is 85 ℃/15-120 ℃/6 s.

7) And (3) cooling: the temperature was 20 ℃.

8) Filling: and (5) ultra-clean filling.

9) Packaging: and (5) ultra-clean packaging.

10) Product inspection: and detecting each index.

11) And (3) marketing: and (5) after the inspection is qualified, the product is listed.

12) And (3) refrigerating: cooling the pasteurized milk to 1-4 deg.C and refrigerating.

The quality test results of the finished low-temperature pasteurized milk are shown in table 6:

TABLE 6

Index (I)	Detecting a value
		Protein, g/100g	3.3
Fat, g/100g	3.8
		Milk solids not fat, g/100g	8.8
The acidity of the water-soluble organic acid,oT	15.0
		alpha-lactalbumin (undenatured), g/100g	0.15
Beta-lactoglobulin (undenatured), g/100g	0.23
		Lactulose, mg/L	45.2
Furfurin, mg/100g protein	42.6
		Shelf life (Low temperature)	3

Comparative example 3

The present comparative example provides a process for the preparation of UHT sterilized milk comprising the steps of:

1) and (3) filtering: the raw milk was passed through an 80 mesh filter.

2) Preheating: the milk was preheated to 60 ℃.

3) Removing impurities: separating milk with a separator at 5000rpm to remove impurities, and separating cream.

4) Homogenizing: the pressure was 30/180 bar.

5) Concentration: the temperature was 70 ℃ and the vacuum degree was-0.6 bar.

6) Pasteurization: the temperature is 72-75 ℃/15 s.

7) And (3) cooling: the temperature was 8 ℃.

8) Preheating: the temperature was 75 ℃.

9) Degassing: the vacuum degree was-0.5 bar.

10) Homogenizing: the pressure was 50/250 bar.

11) And (3) sterilization: the temperature was 138 ℃/4 s.

12) And (3) cooling: the temperature was 25 ℃.

13) Filling: and (5) sterile filling.

14) Packaging: and (7) aseptic packaging.

15) Product inspection: and detecting each index.

16) And (3) marketing: and (5) after the inspection is qualified, the product is listed.

The results of the quality tests of the UHT sterilized milk products are shown in table 7:

TABLE 7

Index (I)	Detecting a value
		Protein, g/100g	3.3
Fat, g/100g	3.8
		Milk solids not fat, g/100g	8.9
The acidity of the water-soluble organic acid,oT	15.5
		alpha-lactalbumin (undenatured), g/100g	0.006
Beta-lactoglobulin (undenatured), g/100g	0.025
		Lactulose, mg/L	268
Furfurin, mg/100g protein	135
		Shelf life (low temperature), day	180

The pasteurized milk of the invention is placed for 3 months at low temperature (1-4 ℃), and compared with the pasteurized milk and the UHT at normal temperature in the current market, the pasteurized milk has the following advantages: 1. the pasteurized milk has low sterilization and storage temperature, has lower microbial index than that of pasteurized milk of the existing market milk, and has better nutrition, mouthfeel and flavor than the pasteurized milk of the market milk; 2. the low-temperature storage time of the pasteurized milk of the invention is far longer than the quality guarantee period of pasteurized milk of the commercial milk; 3. the pasteurized milk has short heating time, low intensity, better flavor and nutrition than UHT sterilized milk, and low content of the byproduct, namely the furosine.

The low temperature pasteurized milk prepared in example 2 was subjected to taste and flavor differentiation ranking with the milk of comparative example 1, comparative example 2 and comparative example 3, respectively.

The rank and rank of the sample (20 persons selected for the taste testing professional panelists were subjected to the taste and flavor ranking method), and the results are shown in table 8.

TABLE 8

As can be seen from the statistical order and results of the comprehensive ranking of mouthfeel and flavor of the product of example 2 of the invention and comparative examples 1-3: the product of example 2 of the invention had a superior mouthfeel and flavor to the products of comparative examples 1-3.