CN118402556B - A method for preparing cream and application thereof - Google Patents

Abstract

The invention relates to the technical field of dairy product preparation, and particularly discloses a method for preparing cream and application thereof. The method for preparing the cream comprises the following steps: (1) Removing part of lactose in animal milk by an ultrafiltration membrane of 50-80nm to make the mass ratio of lactose to fat in the animal milk be (1.0-1.5): (5.0-6.0); (2) separating to obtain cream; (3) Passivating lipase in the cream, and then homogenizing for the first time; (4) carrying out second homogenization after high-temperature sterilization; (5) adding 0.01-0.05%o lactase for enzymolysis. The zero lactose cream prepared by the method provided by the invention has the advantages of avoiding browning of products, reducing peculiar smell, along with small particle size, good uniformity and stable system. The method of the invention greatly reduces the addition of lactase, saves the production cost, has simple whole process and is suitable for industrialized mass production.

Description

A method for preparing cream and application thereof

Technical Field

The invention relates to the technical field of dairy product preparation, in particular to a method for preparing cream and application thereof.

Background Art

Dairy products are a good source of nutrition. Cream is a favorite dairy product of consumers. It can be used to make desserts, coffee, milk tea, etc. It has a wide range of uses. Some consumers are lactose intolerant, which has a negative impact on the intake of dairy products, but this can be solved by eating low-lactose or zero-lactose products. Adding exogenous lactase to the processing and production of zero-lactose dairy products to hydrolyze lactose into monosaccharides that are easily absorbed by the human body is a better method currently used. This method has mild hydrolysis conditions and good taste. It will not destroy the various nutrients in dairy products, and can increase the flavor and sweetness of milk, improve the taste, and improve the absorption and utilization of mineral elements.

The existing Chinese patent CN 113632853A mentions using lactase to hydrolyze raw milk or pasteurized milk and then perform fat separation to obtain lactose-free cream, which is then ultra-high temperature sterilized. However, the disadvantage is that lactase will decompose lactose into glucose and galactose, and ultra-high temperature sterilization will accelerate the Maillard reaction in the product, accelerate browning, and cause sensory discomfort to consumers.

In addition, consumers pursue natural nutrition without additives, but most of the cream products on the market are mainly ingredient products, with stabilizers, emulsifiers, etc. added, which do not meet consumers' demand for no additives. In addition, the presence of aromatic sulfatase in commercial lactase preparations will produce p-methylphenol during storage during the shelf life, causing the product to have an odor. Therefore, it is necessary to further study the preparation of cream.

Summary of the invention

One of the purposes of the present invention is to provide a method for preparing zero-lactose cream with long shelf life, stable system and low p-methylphenol and furosine content.

The present invention provides a method for preparing cream, comprising:

(1) removing part of the lactose in the animal milk through an ultrafiltration membrane of 50-80 nm, so that the mass ratio of lactose to fat in the animal milk is (1.0-1.5): (5.0-6.0);

(2) Separating and obtaining cream;

(3) after the lipase in the cream is inactivated, the first homogenization is performed;

(4) Perform a second homogenization after high temperature sterilization;

(5) Add 0.01-0.05‰ lactase and then perform enzymatic hydrolysis.

The present invention has found that in the current prior art, when preparing low-lactose cream, the commonly used implementation method is: first add lactase to hydrolyze the lactose in the milk, then centrifuge to separate the fat, and ultra-high temperature sterilize the fat; or, first centrifuge to separate the fat in the milk, ultra-high temperature sterilize the fat, and then add lactase to hydrolyze the lactose therein. However, in the first method mentioned above, lactose will be decomposed into glucose and galactose after hydrolysis, and the subsequent ultra-high temperature sterilization will accelerate the Maillard reaction in the product, produce furosine, and accelerate browning. The amount of lactase required to be added in the final product of the second method is about 0.20‰ (if the amount of lactase is reduced, the enzymolysis time needs to be extended, which is not conducive to industrial production). Since the aromatic sulfatase activity can be detected in commercial lactase preparations (Kilic and Lindsay, 2006), it will enter the product system through the addition of lactase, and produce p-methylphenol during the shelf life, causing the product to have an odor. Therefore, it is still necessary to reduce the amount of lactase added in the second method. In addition, it is necessary to further improve the storage stability of cream products at room temperature.

To this end, the present invention has conducted a large number of studies on the preparation method of cream, and finally found that by first removing part of the lactose in animal milk through a membrane process, so that the fat and lactose in the animal milk are at a specific ratio, and then performing the separation of the cream and subsequent lipase passivation, sterilization, homogenization, lactase addition and other steps, the particle size of the final product can be reduced, and the product uniformity and stability under the room temperature shelf life can be improved. And because part of the lactose is removed before the separation of the cream, the amount of lactase added in the final product can be greatly reduced, thereby reducing the introduction of aromatic sulfatase in commercial lactase preparations, reducing the generation of p-methylphenol during the shelf life storage process, and avoiding peculiar smell. Moreover, adding lactase after heat treatment such as sterilization can avoid the generation of browning of the final product, which is beneficial to the health of consumers.

In step (1) of the present invention, the more lactose is removed, the lower the final amount of lactase added can be. However, the present invention has found that before lipase inactivation, sterilization and homogenization, if the ratio of lactose to fat is not within the limits of the present invention, it will have a significant negative impact on the particle size and stability of the final product. Therefore, in step (1), the more lactose is removed, the better.

Preferably, enzymatic hydrolysis is performed after adding 0.02-0.04‰ lactase.

The animal milk of the present invention can be the milk of mammals such as cow's milk, goat's milk, camel's milk, deer's milk, horse's milk, etc.

In step (1) of the method of the present invention, part of the lactose in the animal milk is removed by ultrafiltration and diafiltration to adjust the mass ratio of lactose to fat in the animal milk.

Those skilled in the art can remove lactose from animal milk by conventional membrane processes in the art to adjust the ratio of lactose to fat.

Preferably, in step (1) of the method of the present invention, the method for adjusting the mass ratio of lactose to fat in animal milk comprises:

(A) ultrafiltration of the animal milk using an ultrafiltration membrane with a pore size of 50-80 nm, with a concentration multiple of 1.5-2 times and a transmembrane pressure of 0.2-0.5 MPa to obtain an ultrafiltration retentate;

(B) The ultrafiltration retentate is diafiltrated with 4-6 times the mass of water using an ultrafiltration membrane with a pore size of 50-80 nm at a transmembrane pressure of 0.3-0.6 MPa to obtain a diafiltration retentate for step (2).

The present invention preferably uses a physical method combining ultrafiltration and diafiltration to partially remove lactose in animal milk, and controls the ratio of lactose to fat by adjusting the processing conditions. The method is simple and easy to implement and is suitable for industrial production.

In the present invention, the material of the ultrafiltration membrane can be cellulose, cellulose acetate, polycarbonate, polyvinyl chloride and other conventional materials in the art.

Preferably, the concentration multiple in step (A) is 1.7-1.8 times, and the transmembrane pressure is 0.3-0.4 MPa.

In step (B), diafiltration is performed with 4.5-5.5 times the mass of water, and the transmembrane pressure is 0.4-0.5 MPa, so that the mass ratio of lactose to fat in the animal milk is (1.2-1.3):(5.3-5.8).

In step (3) of the method of the present invention, the total pressure of the first homogenization is 30-80 bar, the secondary pressure is 10-40 bar, and the homogenization temperature is 60-70°C;

In step (4), the total pressure of the second homogenization is 30-70 bar, the secondary pressure is 10-30 bar, and the homogenization temperature is 70-80°C.

The invention can make the texture of the cream product more uniform through double homogenization, and reduce the instability of the product such as aggregation and agglomeration during the shelf life.

Preferably, the total pressure of the first homogenization is 40-70 bar, and the secondary pressure is 20-30 bar; the total pressure of the second homogenization is 40-60 bar, and the secondary pressure is 20-30 bar.

The method of the present invention further comprises the steps of filtering and purifying the animal milk before step (1) to completely remove impurities therein. Preferably, the pore size during the filtration is 50-150 mesh, and the purifying is performed by using a purifier at a preheating temperature of 50-55°C and a speed of 4000-6000 rpm (the time can be determined according to common knowledge in the art, such as 5 minutes).

The present invention can adopt the conventional animal milk impurity removal method in the art to remove impurities therein.

In step (2) of the method of the present invention, the cream is obtained by centrifugation, the centrifugation temperature is 45-60° C., the rotation speed is 5000-7000 rpm, and the fat content of the cream is 35-45 g/100 g.

The present invention can use conventional centrifugation methods in the art to obtain cream with a fat content of 35-45g/100g. The specific centrifugation conditions are conventionally selected, and the present invention does not impose any particular limitation on this.

In step (3) of the method of the present invention, the lipase is passivated by using a tube-in-tube or plate-type indirect heating method, with a heating temperature of 75-95° C. and a heating time of 30 s-5 min.

The present invention can use conventional lipase inactivation methods in the art to treat the cream, and the present invention does not impose any particular limitation on this.

In step (4) of the method of the present invention, the high temperature sterilization adopts direct steam sterilization, the temperature is 135-150°C, and the time is 1-8s; preferably the temperature is 138-145°C, and the time is 3-6s.

In step (5) of the method of the present invention, the enzymatic hydrolysis time is 18-24 hours.

The enzymatic hydrolysis of the present invention is carried out at room temperature (20°C-25°C) to hydrolyze the remaining lactose in the cream. The lactose in the product can be completely removed by using the ultrafiltration diafiltration process in combination with lactase.

As a specific preferred embodiment, the method of the present invention includes the steps of purifying milk, ultrafiltration, diafiltration, centrifugal separation, heat treatment, homogenization, ultra-high temperature sterilization, homogenization, adding lactase, and aseptic filling.

The present invention also provides application of the method in reducing the content of furosine and/or p-methylphenol in cream or reducing the particle size of cream or improving the stability of cream.

The beneficial effects of the present invention are at least:

The method of the present invention can completely remove lactose, and can avoid the production of furosine and p-methylphenol as much as possible, and avoid product browning and odor; and the product particle size is smaller, the uniformity is better, and the system is stable for 6 months at room temperature. In addition, the method of the present invention greatly reduces the addition of lactase, saves production costs, and the overall process is simple, which is suitable for industrial large-scale production.

DETAILED DESCRIPTION

The preferred embodiments of the present invention will be described in detail below in conjunction with examples. It should be understood that the following examples are provided only for the purpose of illustration and are not intended to limit the scope of the present invention. Those skilled in the art may make various modifications and substitutions to the present invention without departing from the purpose and spirit of the present invention.

The experimental methods used in the following examples are conventional methods unless otherwise specified. The materials, reagents, etc. used in the following examples are commercially available or prepared according to conventional methods in the art unless otherwise specified.

In the specific implementation manner of the present invention, the contents of lactose and fat in the diafiltration step in each example were detected using the FOSS multifunctional dairy component rapid analyzer MilkoScan FT120.

In a specific embodiment of the present invention, lactase is commercially available β-galactosidase. In Example 1, Example 4 and Comparative Example 1, conventional commercially available product 1 (production batch number: 22050519; origin: Nanning, Guangxi) has an aromatic sulfatase content of 0.225 mmol/L; in Example 2 and Comparative Example 2, conventional commercially available product 2 (production batch number: 220202006; origin: Hefei, Anhui) has an aromatic sulfatase content of 0.231 mmol/L; in Example 3, conventional commercially available product 3 (production batch number: 20220614; origin: Shanghai) has an aromatic sulfatase content of 0.204 mmol/L.

Arylsulfatase was detected using an arylsulfatase detection kit (fluorescence assay).

Example 1

This embodiment provides a method for preparing cream, which specifically includes:

1. Milk purification: filter all the milk and remove impurities through a milk purifier, filter 50 mesh, set the speed of the milk purifier to 4000rpm, preheat to 50℃, and process for 5min;

2. Ultrafiltration: ultrafiltration is performed using an ultrafiltration membrane with a pore size of 50 nm, with a concentration multiple of 1.5 times and a transmembrane pressure of 0.2 MPa, and the retentate of this step is collected;

3. Diafiltration: using an ultrafiltration membrane with a pore size of 50 nm, the retentate obtained by ultrafiltration was diafiltered with 4 times the mass of water (based on the mass of the retentate of ultrafiltration), and the transmembrane pressure was 0.3 MPa, and a retentate with a lactose and fat content ratio of 1.0:5.0 was obtained;

4. Centrifugal separation: centrifuge the retentate obtained by diafiltration at a temperature of 45°C and a speed of 5000 rpm until a raw cream having a fat content of 35-45 g/100 g is obtained;

5. Heat treatment: heat treat the raw cream in a tube-type indirect sterilization method at a temperature of 75°C for 5 minutes;

6. Homogenization: the first homogenization, the total homogenization pressure is 30 bar, the secondary pressure is 10 bar, and the homogenization temperature is 60 ° C;

7. Ultra-high temperature sterilization, steam direct sterilization, temperature 135℃, 8s;

8. Homogenization, second homogenization, total homogenization pressure 30 bar, secondary pressure 10 bar, homogenization temperature 70 ° C;

9. After cooling to room temperature, add lactase online aseptically, and the added mass of lactase is 0.01‰ of the mass of the liquid;

10. Aseptic filling: Aseptically fill the cooled and enzyme-added cream and allow it to hydrolyze for 18 hours.

Example 2

This embodiment provides a method for preparing cream, which specifically includes:

1. Milk purification: filter all the milk and remove impurities through a milk purifier, filter 150 mesh, set the speed of the milk purifier to 6000rpm, preheat to 55℃, and process for 5min;

2. Ultrafiltration: ultrafiltration is performed using an ultrafiltration membrane with a pore size of 80 nm, with a concentration multiple of 1.7 times and a transmembrane pressure of 0.3 MPa, and the retentate of this step is collected;

3. Diafiltration: using an ultrafiltration membrane with a pore size of 80 nm, the retentate obtained by ultrafiltration was diafiltered with 4.5 times the mass of water (based on the mass of the retentate of ultrafiltration), and the transmembrane pressure was 0.4 MPa, and a retentate with a lactose and fat content ratio of 1.2:5.3 was obtained;

4. Centrifugal separation: centrifuge the retentate obtained by diafiltration at a temperature of 60° C. and a rotation speed of 6000 rpm until a raw cream having a fat content of 35-45 g/100 g is obtained;

5. Heat treatment: heat treat the raw cream by plate-type indirect sterilization method at a temperature of 95°C for 30 seconds;

6. Homogenization: the first homogenization, the total homogenization pressure is 40 bar, the secondary pressure is 20 bar, and the homogenization temperature is 70 ° C;

7. Ultra-high temperature sterilization, steam direct sterilization, temperature 145℃, 3s;

8. Homogenization, second homogenization, total homogenization pressure 60 bar, secondary pressure 30 bar, homogenization temperature 80 ° C;

9. After cooling to room temperature, add lactase online aseptically, and the mass of lactase added is 0.02‰ of the mass of the feed liquid;

10. Aseptic filling: Aseptically fill the cooled and enzyme-added cream and allow it to hydrolyze for 24 hours.

Example 3

This embodiment provides a method for preparing cream, which specifically includes:

1. Milk purification: filter all the milk and remove impurities through a milk purifier, filter 120 mesh, set the speed of the milk purifier to 4500rpm, preheat to 53℃, and process for 5min;

2. Ultrafiltration: ultrafiltration is performed using an ultrafiltration membrane with a pore size of 60 nm, with a concentration multiple of 1.8 times and a transmembrane pressure of 0.4 MPa, and the retentate of this step is collected;

3. Diafiltration: using an ultrafiltration membrane with a pore size of 60 nm, the retentate obtained by ultrafiltration was diafiltered with 5.5 times the mass of water (based on the mass of the retentate of ultrafiltration), and the transmembrane pressure was 0.5 MPa, and a retentate with a lactose and fat content ratio of 1.3:5.8 was obtained;

4. Centrifugal separation: centrifuge the retentate obtained by diafiltration at a temperature of 50° C. and a rotation speed of 7000 rpm until a raw cream having a fat content of 35-45 g/100 g is obtained;

5. Heat treatment: heat treat the raw cream in a tube-type indirect sterilization method at a temperature of 80°C for 2 minutes;

6. Homogenization: the first homogenization, the total homogenization pressure is 70 bar, the secondary pressure is 30 bar, and the homogenization temperature is 65 °C;

7. Ultra-high temperature sterilization, steam direct sterilization, temperature 150℃, 1s;

8. Homogenization, second homogenization, total homogenization pressure 40 bar, secondary pressure 20 bar, homogenization temperature 75 ° C;

9. After cooling to room temperature, add lactase online aseptically, and the mass of lactase added is 0.04‰ of the mass of the liquid;

10. Aseptic filling: Aseptically fill the cooled and enzyme-added cream; allow to hydrolyze for 20 hours.

Example 4

This embodiment provides a method for preparing cream, which specifically includes:

1. Milk purification: filter all the milk and remove impurities through a milk purifier, filter 100 mesh, set the speed of the milk purifier to 5000rpm, preheat to 54℃, and process for 5min;

2. Ultrafiltration: ultrafiltration is performed using an ultrafiltration membrane with a pore size of 70 nm, with a concentration multiple of 2 times and a transmembrane pressure of 0.5 MPa, and the retentate of this step is collected;

3. Diafiltration: using an ultrafiltration membrane with a pore size of 70 nm, the retentate obtained by ultrafiltration was diafiltered with 6 times the mass of water (based on the mass of the retentate of ultrafiltration), and the transmembrane pressure was 0.6 MPa, and a retentate with a lactose and fat content ratio of 1.5:6.0 was obtained;

4. Centrifugal separation: centrifuge the retentate obtained by diafiltration at a temperature of 55°C and a speed of 5500 rpm until a raw cream having a fat content of 35-45 g/100 g is obtained;

5. Heat treatment: heat treat the raw cream by plate-type indirect sterilization method at a temperature of 90°C for 1 minute;

6. Homogenization: the first homogenization, the total homogenization pressure is 80 bar, the secondary pressure is 40 bar, and the homogenization temperature is 62 °C;

7. Ultra-high temperature sterilization, steam direct sterilization, temperature 138℃, 6s;

8. Homogenization, second homogenization, total homogenization pressure 70 bar, secondary pressure 30 bar, homogenization temperature 72 ° C;

9. After cooling to room temperature, add lactase online aseptically, and the added mass of lactase is 0.05‰ of the mass of the liquid;

10. Aseptic filling: Aseptically fill the cooled and enzyme-added cream; allow to hydrolyze for 22 hours.

Comparative Example 1

This comparative example provides a method for preparing cream, which does not involve ultrafiltration or diafiltration of raw milk, but directly separates fat and then adds lactase, specifically comprising:

1. Milk purification: filter all the milk and remove impurities through a milk purifier, filter through 50 mesh, set the speed of the milk purifier to 4000rpm, and preheat to 50℃;

2. Centrifuge at 45°C and 5000 rpm until the raw cream with a fat content of 35-45 g/100 g is obtained;

3. Heat treatment: heat treat the raw cream in a tube-type indirect sterilization method at a temperature of 75°C for 5 minutes;

4. Homogenization: the first homogenization, the total homogenization pressure is 30 bar, the secondary pressure is 10 bar, and the homogenization temperature is 60 ° C;

5. Ultra-high temperature sterilization, steam direct sterilization, temperature 135℃, 8s;

6. Homogenization, second homogenization, total homogenization pressure 30 bar, secondary pressure 10 bar, homogenization temperature 70 ° C;

7. After cooling to room temperature, add lactase online aseptically, and the mass of lactase added is 0.20‰ of the mass of the liquid;

8. Aseptic filling: Aseptically fill the cooled and enzyme-added cream and allow it to hydrolyze for 18 hours.

Comparative Example 2

This comparative example provides a method for preparing cream, wherein lactase is added before ultra-high temperature sterilization, and specifically comprises:

1. Milk purification: filter all the milk and remove impurities through a milk purifier, filter 150 mesh, set the speed of the milk purifier to 6000rpm, and preheat to 55℃;

2. After cooling to room temperature, add lactase online aseptically, the mass of lactase added is 0.20‰ of the mass of the feed liquid, and let it stand for enzymolysis for 24 hours;

3. Centrifugal separation: add the enzymatically hydrolyzed milk and centrifuge at a temperature of 60°C and a speed of 6000 rpm until a raw cream having a fat content of 35-45 g/100 g is obtained;

4. Heat treatment: heat treat the raw cream by plate-type indirect sterilization method at a temperature of 95°C for 30 seconds;

5. Homogenization: the first homogenization, the total homogenization pressure is 40 bar, the secondary pressure is 20 bar, and the homogenization temperature is 70 ° C;

6. Ultra-high temperature sterilization, steam direct sterilization, temperature 145℃, 3s;

7. Homogenization, second homogenization, total homogenization pressure 60 bar, secondary pressure 30 bar, homogenization temperature 80 ° C;

8. Aseptic filling: aseptically fill the cream after cooling to room temperature.

Comparative Example 3

This comparative example provides a method for preparing light cream, which is basically the same as the preparation method of Example 3, except that step 6 (the first homogenization) in Example 3 is not performed, and ultra-high temperature sterilization is performed directly after the heat treatment.

Comparative Example 4

This comparative example provides a method for preparing light cream, which is basically the same as the preparation method of Example 4, except that step 8 (second homogenization) in Example 4 is not performed, and lactase is added directly after ultra-high temperature sterilization.

Comparative Example 5

This comparative example provides a method for preparing light cream, which is basically the same as the preparation method in Example 1, except that in step 3, the retentate obtained by ultrafiltration is diafiltered with 7 times the mass of water (based on the mass of the retentate of ultrafiltration), and the ratio of lactose to fat in the diafiltration retentate is controlled to be 0.7:5.0.

Comparative Example 6

This comparative example provides a method for preparing light cream, which is basically the same as the preparation method of Example 1, except that in step 3, the retentate obtained by ultrafiltration is diafiltered with 3 times the mass of water (based on the mass of the retentate of ultrafiltration), and the ratio of lactose to fat in the diafiltration retentate is controlled to be 1.8:5.0.

Experimental example

1. Finished product test results and sensory results

After the finished cream products prepared in the examples and comparative examples were stored at room temperature for 6 months, the fat, lactose, carbohydrate, furosine content and color were tested. The results are shown in Table 1.

Table 1 Test results and sensory results of finished products stored at room temperature for 6 months

According to the index detection and sensory evaluation results of the samples stored at room temperature for 6 months, the fat content of the samples of Examples 1-4 and Comparative Examples 1-6 is relatively close, and no lactose is detected. The carbohydrates of the samples of Examples 1-4 and Comparative Examples 3-6 are much less than those of the samples of Comparative Examples 1-2. The process of Comparative Example 1-2 does not use ultrafiltration and diafiltration to remove lactose, and all lactose is converted into glucose and galactose, so the carbohydrate content is relatively high. The furosine of the samples of Examples 1-4 and Comparative Examples 3-6 is much less than that of the samples of Comparative Examples 1-2, indicating that the Maillard reaction of Comparative Examples 1 and 2 is more intense than that of other embodiments and comparative examples. The color of the samples of Examples 1-4 and Comparative Examples 3-6 is milky white, the color of the sample of Comparative Example 1 is slightly browned, and the sample of Comparative Example 2 is severely browned, which is related to the addition of lactase before ultra-high temperature sterilization. The samples of Examples 1-4 and Comparative Examples 1-2 are uniform and consistent, with good fluidity, while Comparative Examples 3 and 4 produce visible lumps, which is related to only one homogenization. The ratio of lactose to fat in the samples of Comparative Examples 5 and 6 before heat treatment and homogenization was not within the limits of the present invention, and slight fat accumulation occurred after being placed for 6 months.

2. Results of follow-up test of p-methylphenol during 6-month shelf life at room temperature

The creams prepared in Example 1 and Comparative Example 1 were stored at room temperature, and the p-methylphenol content was tracked and detected for 6 months. The results are shown in Table 2.

Table 2 Results of p-methylphenol concentration tracking test during 6-month shelf life at room temperature

In Example 1, less lactase was added, and thus less aromatic sulfatase was introduced into the product, resulting in a lower concentration of p-methylphenol. In Comparative Example 1, a conventional amount of lactase (0.20‰) was added, and more aromatic sulfatase was introduced into the product, resulting in a higher concentration of p-methylphenol, which showed an upward trend for 6 months. In other embodiments and comparative examples, there was also a situation where the less aromatic sulfatase introduced by the addition of lactase, the lower the p-methylphenol concentration.

For the detection method of p-methylphenol, please refer to GB/T 5009.30 Determination of butylated hydroxyanisole (BHA) and 2,6-di-tert-butylated p-cresol (BHT) in food.

3. Particle size tracking test results after 6 months shelf life at room temperature

The creams prepared in Examples 1-4 and Comparative Examples 1-2 and 5-6 were stored at room temperature, and the particle size results were tracked and tested for 6 months. The results are shown in Table 3.

Table 3 Particle size test results after 6-month shelf life at room temperature

The ratio of lactose to fat content in the sample of Example 1-4 after the diafiltration step is (1.0-1.5): (5.0-6.0). Under this ratio, the particle size of the product is smaller, it is not easy to aggregate during the shelf life storage process, and the product system is more uniform and stable. Example 2-3 adopts the preferred parameters, and the particle size is smaller than that of Example 1 and 4. Comparative Example 1-2 is a zero lactose cream produced by a conventional method. The particle size of the sample tends to increase during the shelf life, which is not as stable as the particle size change of Example 1-4. The particle size of the sample of Comparative Example 5-6 tends to continue to increase during the shelf life, and unstable agglomeration is prone to occur.

Although the present invention has been described in detail above with general descriptions and specific embodiments, it is obvious to those skilled in the art that some modifications or improvements can be made on the basis of the present invention. Therefore, these modifications or improvements made on the basis of not departing from the spirit of the present invention all belong to the scope of protection claimed by the present invention.

Claims (8)

1. A method for preparing cream, comprising: (1) removing part of the lactose in the animal milk through an ultrafiltration membrane of 50-80 nm, so that the mass ratio of lactose to fat in the animal milk is (1.0-1.5): (5.0-6.0); (2) Separating and obtaining cream; (3) after the lipase in the cream is inactivated, homogenization is performed for the first time; (4) Perform a second homogenization after high temperature sterilization; (5) Add 0.01-0.05‰ lactase and perform enzymolysis; In step (1), part of the lactose in the animal milk is removed by ultrafiltration and diafiltration to adjust the mass ratio of lactose to fat in the animal milk; Methods for adjusting the mass ratio of lactose and fat in animal milk include: (A) ultrafiltration of the animal milk using an ultrafiltration membrane with a pore size of 50-80 nm, with a concentration multiple of 1.5-2 times and a transmembrane pressure of 0.2-0.5 MPa to obtain an ultrafiltration retentate; (B) The ultrafiltration retentate is diafiltrated with 4-6 times the mass of water using an ultrafiltration membrane with a pore size of 50-80 nm at a transmembrane pressure of 0.3-0.6 MPa to obtain a diafiltration retentate for step (2). 2. The method for preparing cream according to claim 1, characterized in that: In step (3), the total pressure of the first homogenization is 30-80 bar, the secondary pressure is 10-40 bar, and the homogenization temperature is 60-70°C; In step (4), the total pressure of the second homogenization is 30-70 bar, the secondary pressure is 10-30 bar, and the homogenization temperature is 70-80°C. 3. The method for preparing cream according to any one of claims 1 to 2, characterized in that, before step (1), it also includes the steps of filtering and purifying the animal milk, wherein the pore size during the filtration is 50-150 mesh, and the purifying is performed by using a purifier preheated at 50-55°C and 4000-6000rpm. 4. The method for preparing cream according to any one of claims 1 to 2, characterized in that in step (2), the cream is obtained by centrifugation, the centrifugation temperature is 45-60°C, the rotation speed is 5000-7000 rpm, and the fat content of the cream is 35-45 g/100 g. 5. The method for preparing cream according to any one of claims 1 to 2, characterized in that: In step (3), the lipase is passivated by using a tube-in-tube or plate-type indirect heating method, with a heating temperature of 75-95° C. and a heating time of 30 s-5 min. 6. The method for preparing cream according to any one of claims 1-2, characterized in that in step (4), the high temperature sterilization adopts direct steam sterilization, the temperature is 135-150°C, and the time is 1-8s. 7. The method for preparing cream according to any one of claims 1-2, characterized in that in step (5), the enzymatic hydrolysis time is 18-24 hours. 8. Use of the method according to any one of claims 1 to 7 in reducing the content of furosine and/or p-methylphenol in cream, reducing the particle size of cream, or improving the stability of cream.