阅读说明：本技术 一种牛奶产品及其制备方法、乳制品及其制备方法 (Milk product and preparation method thereof, and milk product and preparation method thereof ) 是由 王秋岭 李艳君 张海斌 孙云峰 于 2020-06-24 设计创作，主要内容包括：本发明涉及牛奶产品及其制备方法、乳制品及其制备方法,尤其是具有高营养活性和高生物安全性的牛奶产品及其制备方法。本发明牛奶产品的制备方法包括如下步骤：步骤(1)净乳；步骤(2)RO膜浓缩；步骤(3)脱气；步骤(4)分离；步骤(5)稀奶油高温杀菌；步骤(6)脱脂奶物理除菌；步骤(7)回填；步骤(8)均质；步骤(9)杀菌处理。牛奶产品包含在0-10℃条件下贮藏第42天小于等于5000cfu/mL的菌落总数、小于等于11mg/100g蛋白质的糠氨酸、1500-20000U/L的乳过氧化物酶、35-120mg/L的乳铁蛋白、100-1000mg/L的免疫球蛋白、以及200-800μg/L的溶菌酶。(The invention relates to a milk product and a preparation method thereof, in particular to a milk product with high nutritional activity and high biological safety and a preparation method thereof. The preparation method of the milk product comprises the following steps: step (1), cleaning milk; step (2), concentrating the RO membrane; degassing in the step (3); separating in the step (4); step (5), sterilizing the cream at high temperature; step (6), physically sterilizing the skim milk; backfilling in the step (7); homogenizing; and (9) sterilizing. The milk product comprises total colony number less than or equal to 5000cfu/mL at 42 th day of storage at 0-10 ℃, furfuryl acid less than or equal to 11mg/100g protein, lactoperoxidase of 1500-20000U/L, lactoferrin of 35-120mg/L, immunoglobulin of 100-1000mg/L, and lysozyme of 200-800 μ g/L.)

1. A method of preparing a milk product comprising the steps of:

step (1), milk purification: filtering the raw milk by a sieve of 80-600 meshes at the temperature of 2-10 ℃, and centrifuging at the rotating speed of 4000-6000 rpm;

step (2) RO membrane concentration: concentrating the product obtained in step (1) at 4-15 deg.C with RO membrane with membrane pressure of 4-6bar and membrane pore diameter of 0.001-0.0005 μm to obtain retentate containing protein of not less than 3.2g/100 g;

degassing in step (3): degassing the product obtained in the step (2) at a temperature of 55-65 ℃ and a pressure of-0.04 to-0.09 MPa;

and (4) separation: separating the product obtained in the step (3) under the conditions that the separation temperature is 55-65 ℃ and the separation rotating speed is 5000-;

step (5), high-temperature sterilization of the cream: sterilizing the dilute cream obtained in the step (4) at the temperature of 115 ℃ and 135 ℃ for 2-15 seconds, and cooling to 30-55 ℃;

and (6) physical sterilization of the skim milk: carrying out centrifugal sterilization on the skim milk obtained in the step (4) by using a sterilization separator under the conditions that the temperature is 55-60 ℃ and the centrifugal force is 5000-10000g, and then carrying out MF microfiltration sterilization by using a ceramic membrane, wherein the membrane passing temperature is 55-60 ℃, the membrane pressure is 3-6bar, and the membrane pore size is 0.5-0.8 mu m;

backfilling in the step (7): mixing the cream obtained in the step (5) and the skim milk obtained in the step (6) on line at a feed liquid temperature of 50-60 ℃;

homogenizing in step (8): homogenizing the product obtained in step (7) at 50-60 deg.C and 170-230 bar;

and (9) sterilization treatment: and (4) performing plate-type sterilization or tubular sterilization on the product obtained in the step (8).

2. A method of preparing a milk product according to claim 1, wherein:

the fat content of the cream obtained in the step (4) is 45-65g/100g, and the fat content of the skim milk obtained in the step (4) is less than or equal to 0.06g/100 g.

3. A method of preparing a milk product according to claim 1, wherein:

in the step (5), the dilute cream obtained in the step (4) is sterilized at the temperature of 120 ℃ and 128 ℃ for 4-8 seconds and then cooled to 30-55 ℃.

4. A method of preparing a milk product according to claim 1, wherein:

the protein content of the feed liquid obtained in the step (7) after on-line mixing is 3.0g/100g-4.0g/100g, and the fat content is 0.01g/100g-5.0g/100 g.

5. A method of preparing a milk product according to claim 4, wherein:

the fat content is 0.06-0.1g/100g or 0.1-1.5g/100g or 1.5-3.0g/100g or 3.0-3.5g/100g or 3.5-5.0g/100 g.

6. A method of preparing a milk product according to claim 1, wherein:

in the step (9), the sterilization temperature is 62-65 ℃, and the holding time is 25-35 min; or sterilizing at 72-75 deg.C for 12-15 s.

7. A milk product obtainable by the method of preparing a milk product according to any one of claims 1 to 6.

8. A milk product according to claim 7, characterized in that: comprises total colony number less than or equal to 5000cfu/mL at 42 days of storage at 0-10 ℃, furfuryl acid less than or equal to 11mg/100g protein, lactoperoxidase of 1500-20000U/L, lactoferrin of 35-120mg/L, immunoglobulin of 100-1000mg/L, and lysozyme of 200-800 μ g/L.

9. A method of producing a dairy product comprising the method of producing a milk product of any one of claims 1-6.

10. A dairy product produced by the method of producing a dairy product of claim 9.

Technical Field

The invention relates to the field of dairy products, in particular to a milk product with high nutritional activity and high biological safety and a preparation method thereof, and a dairy product and a preparation method thereof.

Background

Milk is known as 'white blood' and is always considered as one of the most complete nutritious foods in nature, and substances playing a role of functional components in the milk are mainly active substances in the milk, such as: lactoferrin, immunoglobulin, lactoperoxidase, lysozyme and the like, and the active substances mainly have the effects of immunoregulation, antibiosis, antivirus, anticancer, ACE (angiotensin converting enzyme) activity inhibition and the like, but the active substances in the milk can cause a great loss of the nutrient substances due to heat treatment with different sterilization degrees in the processing process, so that the current method for preparing the milk still has room for improvement.

The existing milk preparation process has the following specific problems:

(1) sterilizing milk: the sterilization intensity of the sterilized milk is generally at 135-145 ℃ for 2-6s, the heat treatment degree is serious, and although the long shelf life of the milk product is ensured, most of the active nutrient components in the milk are destroyed to cause the loss of the nutrient components.

(2) High-temperature sterilization milk: compared with the sterilized milk, the high-temperature sterilized milk has the sterilization intensity between that of pasteurized milk and that of sterilized milk, has a shorter shelf life than that of the sterilized milk, but has more loss of nutrient components and more loss of active nutrient components in the milk.

(3) Traditional pasteurization: the whole heat treatment time from preheating to sterilization to cooling to filling of the traditional pasteurized milk is longer, and the heat load of the milk is serious. The final product has high microbial content and short shelf life.

(4) Pasteurized milk: compared with the traditional pasteurized milk, the currently used pasteurizing process has incomplete treatment and short shelf life (1-7 days), cannot adapt to the circulation of urban products of two or three lines, and cannot meet the large demand of consumers on pasteurized milk.

Disclosure of Invention

Technical problem to be solved

Based on the problems existing in the existing milk preparation process, the inventor of the invention carries out a great deal of research, and aims to research a milk product which is suitable for the requirements of modern consumers and is suitable for industrial production and a preparation method thereof.

Technical scheme for solving problems

In order to achieve the above object, the present invention adopts the following technical solutions.

According to one aspect of the present invention, there is provided a method of preparing a milk product, comprising the steps of:

step (1), milk purification: filtering the raw milk by a sieve of 80-600 meshes at the temperature of 2-10 ℃, and centrifuging at the rotating speed of 4000-6000 rpm;

step (2) RO membrane concentration: concentrating the product obtained in step (1) at 4-15 deg.C with RO membrane with membrane pressure of 4-6bar and membrane pore diameter of 0.001-0.0005 μm to obtain retentate containing protein of not less than 3.2g/100 g;

degassing in step (3): degassing the product obtained in the step (2) at a temperature of 55-65 ℃ and a pressure of-0.04 to-0.09 MPa;

and (4) separation: separating the product obtained in the step (3) under the conditions that the separation temperature is 55-65 ℃ and the separation rotating speed is 5000-;

step (5), high-temperature sterilization of the cream: sterilizing the dilute cream obtained in the step (4) at the temperature of 115 ℃ and 135 ℃ for 2-15 seconds, and cooling to 30-55 ℃;

and (6) physical sterilization of the skim milk: carrying out centrifugal sterilization on the skim milk obtained in the step (4) by using a sterilization separator under the conditions that the temperature is 55-60 ℃ and the centrifugal force is 5000-10000g, and then carrying out MF microfiltration sterilization by using a ceramic membrane, wherein the membrane passing temperature is 55-60 ℃, the membrane pressure is 3-6bar, and the membrane pore size is 0.5-0.8 mu m;

backfilling in the step (7): mixing the cream obtained in the step (5) and the skim milk obtained in the step (6) on line at a feed liquid temperature of 50-60 ℃;

homogenizing in step (8): homogenizing the product obtained in step (7) at 50-60 deg.C and 170-230 bar;

and (9) sterilization treatment: and (4) performing plate-type sterilization or tubular sterilization on the product obtained in the step (8).

The fat content of the cream obtained in the above step (4) may be 45 to 65g/100 g.

The fat content in the skim milk obtained in the step (4) may be not more than 0.06g/100 g.

In the step (5), the diluted cream obtained in the step (4) can be cooled to 30-55 ℃ after being sterilized at the temperature of 120-128 ℃ for 4-8 seconds.

The protein content in the on-line mixed feed liquid obtained in the step (7) can be 3.0g/100g-4.0g/100g, and the fat content can be 0.01g/100g-5.0g/100 g.

The fat content may be 0.06-0.1g/100g or 0.1-1.5g/100g or 1.5-3.0g/100g or 3.0-3.5g/100g or 3.5-5.0g/100 g.

In the step (9), the sterilization temperature can be 62-65 ℃, and the holding time can be 25-30 min.

In the step (9), the sterilization temperature can be 72-75 ℃, and the holding time can be 12-15 s.

According to another aspect of the present invention, there is provided a milk product obtained by the method of preparing a milk product as described above.

The milk product comprises the total number of colonies less than or equal to 5000cfu/mL at the 42 th day of storage at the temperature of 0-10 ℃, 11mg/100g of protein of furfuryl acid, 1500-20000U/L of lactoperoxidase, 35-120mg/L of lactoferrin, 100-1000mg/L of immunoglobulin and 200-800 mu g/L of lysozyme.

According to a further aspect of the invention, a method for preparing a dairy product is provided, comprising the method for preparing a milk product as described above.

According to a further aspect of the invention, there is provided a dairy product produced by the method of producing a dairy product described above.

Advantageous effects

According to the invention, the obtained milk greatly retains active nutritional ingredients in the original milk (the active nutritional ingredients are not high-temperature resistant, and all active nutritional substances can be lost under the high-temperature condition), and the microbial residual quantity is low, so that the obtained milk has high biological safety and nutritional activity, and has fresh and sweet, smooth and good mouthfeel with milk fragrance.

On the other hand, according to the preparation method disclosed by the invention, the obtained product is rich in most of active nutritional ingredients in the original milk, so that the total bacterial colony content in the milk product is reduced while the taste of the product is ensured, the biological safety of the milk product is greatly improved, and the quality guarantee period of the milk is prolonged.

Detailed Description

Hereinafter, the present invention will be described by way of examples for better understanding, but the scope of the present invention is not limited to the following examples. Those who do not specify specific conditions in the following examples are conducted under conventional conditions or conditions recommended by the manufacturer. The reagents or instruments used are not indicated by the manufacturer, and are all conventional products commercially available.

The following describes embodiments of the present invention in detail. The following described embodiments are exemplary only for solving the present invention and are not to be construed as limiting the present invention.

According to one aspect of the invention, there is provided a milk product comprising: total number of colonies of 5000cfu/mL or less, preferably 1000cfu/mL or less on 42 th day of storage at 0-10 ℃; less than or equal to 11mg/100g protein of furfuryl acid, preferably 9-10.8mg/100g protein of furfuryl acid; 1500-20000U/L lactoperoxidase, preferably 2000-10000U/L lactoperoxidase, more preferably 4000-7000U/L lactoperoxidase; 35-120mg/L of lactoferrin, preferably 50-110mg/L of lactoferrin, preferably 70-100mg/L of lactoferrin; 100-1000mg/L immunoglobulin, preferably 280-800mg/L immunoglobulin; more preferably 300-650mg/L of immunoglobulin; 200-800. mu.g/L lysozyme, preferably 210-400. mu.g/L lysozyme. The milk is rich in nutritional components such as lactoperoxidase, lactoferrin, immunoglobulin, lysozyme, etc., and retains most of the nutritional value of milk. The lactoperoxidase content is high, the furosine content is low, the loss of heated nutrient substances of the product is low, the primary nutrient retention rate is high, and the total number of bacteria is low, so that the biological safety risk of the product is reduced, and the quality guarantee period of the product is prolonged. In addition, the milk is rich in milk fragrance, has the characteristics of fresh and sweet taste, smoothness and the like, and has good flavor and mouthfeel.

According to another aspect of the invention, a method of preparing a milk product is provided. The method comprises the following steps:

(1) milk purification treatment

In this step, the raw milk is subjected to a cold milk purification treatment in order to remove impurities from the raw milk.

According to an embodiment of the present invention, the temperature of the cold purified milk is 2 to 10 ℃, which comprises filtering the raw milk through a sieve of 80 to 600 mesh (e.g., 80 mesh, 100 mesh, 150 mesh, 200 mesh, 250 mesh, 300 mesh, 350 mesh, 400 mesh, 450 mesh, 500 mesh, 550 mesh, 600 mesh) to remove impurities mixed in the raw milk, and then centrifuging at a rotation speed of 4000-6000rpm (e.g., 4000rpm, 4500rpm, 5000rpm, 5500rpm, 6000rpm) to remove impurities such as non-milk cells in the raw milk.

It should be noted that the term "raw milk" as used herein refers to fresh cow's milk collected from the cow's udder and not further processed.

(2) RO Membrane concentration

In this step, an RO membrane treatment is performed to concentrate and increase the protein and fat content of the milk product.

The milk produced by the cows of different producing areas or different varieties has great difference in components, even if the milk produced by the same cow at different time has certain fluctuation in chemical components, and in order to ensure that the physicochemical indexes of protein, fat and the like of the product are stable and consistent, the indexes need to be adjusted within an allowable range.

According to the embodiment of the invention, the RO membrane is used for concentration, and the obtained protein of the liquid cut-off is not less than 3.2g/100 g. Thus, a milk product with an ideal target protein content is obtained.

According to an embodiment of the present invention, RO membrane concentration is performed at a temperature of 4 to 15 ℃ (e.g., 4 ℃, 5 ℃, 6 ℃, 7 ℃, 8 ℃, 9 ℃, 10 ℃, 12 ℃, 15 ℃) to thereby avoid loss of the nutritionally active substance due to excessive temperature, a membrane pressure of 4 to 6bar, and a membrane pore size of 0.001 to 0.0005 μm (e.g., 0.001 μm, 0.0009 μm, 0.0008 μm, 0.0007 μm, 0.0006 μm, 0.0005 μm), thereby removing moisture from raw milk. In the present invention, the retention of the nutritionally active substances in the raw materials is ensured by such cryoconcentration.

(3) Degassing of gases

In this step, raw milk is subjected to a degassing treatment. Therefore, the bad gas mixed in the raw milk and the volatile components influencing the mouthfeel are removed, and the mouthfeel of the product is further improved.

According to the embodiment of the present invention, the temperature of the degreasing treatment is 55 to 65 ℃ (e.g., 55 ℃, 56 ℃, 58 ℃, 60 ℃, 62 ℃, 64 ℃, 65 ℃) and the pressure is-0.04 to-0.09 Mpa (e.g., -0.04Mpa, -0.05Mpa, -0.06Mpa, -0.07Mpa, -0.08Mpa, -0.09Mpa), thereby removing gases and undesirable volatile components mixed in the raw milk and improving the taste of the product.

(4) Separation of

In the step, the product is separated into the skim milk and the cream so as to facilitate subsequent physical sterilization of the skim milk and subsequent high-temperature sterilization of the cream.

In an embodiment of the present invention, the separation temperature is 55 to 65 ℃ (e.g., 55 ℃, 56 ℃, 58 ℃, 60 ℃, 62 ℃, 64 ℃, 65 ℃) and the separation rotation speed is 5000-7500rpm (e.g., 5000rpm, 5100rpm, 5200rpm, 5300rpm, 5400rpm, 5500rpm, 5800rpm, 6000rpm, 6200rpm, 6500rpm, 6800rpm, 7000rpm, 7100rpm, 7200rpm, 7300rpm, 7400rpm, 7500rpm), thereby separating the skim milk and the thin cream in the raw milk, the fat content of the obtained thin cream is 45 to 65g/100g, and the fat content of the obtained skim milk is 0.06g/100g or less.

In the invention, the high-speed separation is adopted, so that the content of residual protein in the cream is further reduced, the protein denaturation rate in subsequent cream high-temperature sterilization can be further reduced, the retention rate of active substances is improved, and the content of the furosine is reduced.

(5) High temperature sterilization

In the step, the separated cream is sterilized at high temperature, so that microorganisms in the cream are removed, and the traditional tubular sterilization or plate sterilization is adopted, so that the microorganisms such as bacteria, spores and the like in the milk are effectively killed, and the quality guarantee period of the milk is prolonged.

According to the embodiment of the invention, the high-temperature sterilization treatment is carried out for 2-15s (such as 2s, 3s, 4s, 5s, 6s, 7s, 8s, 10s, 12s and 15s) at the temperature of 115-135 ℃ (such as 115 ℃, 118 ℃, 120 ℃, 125 ℃, 128 ℃, 130 ℃, 132 ℃ and 135 ℃), preferably for 4-8s at the temperature of 120-128 ℃, so that the microorganisms can be effectively killed, especially the biological safety of the product is ensured on the premise of reducing the loss of nutrient substances. According to the invention, the total number of the colonies of the cream is less than 1 cfu/ml.

(6) Physical sterilization

In the step, the skim milk obtained by separation is subjected to degerming by a degerming separator and MF microfiltration degerming, so that microorganisms in the skim milk are removed, the nutrient content of the product is ensured, the microorganisms in the product are removed, and the shelf life of the product is prolonged.

According to the embodiment of the invention, the treatment of the sterilizing separator is carried out at 55-60 ℃, the centrifugal force is 5000-10000g, the sterilizing separator can effectively remove spores and heat-resistant spores in a sample, and the removal rate of the spores is 90-95%. The sterilization rate of the microorganisms is 75-80%, and the microorganisms in the skim milk are removed to a great extent. The process parameters determined according to the invention can well balance the loss ratio of the protein and the sterilization efficiency.

According to the embodiment of the invention, the skim milk which is passed through the degerming separator is subjected to MF microfiltration degerming, the membrane temperature is 55-60 ℃ (for example, 55 ℃, 56 ℃, 57 ℃, 58 ℃, 59 ℃, 60 ℃), the membrane pressure is 3-6bar (for example, 3bar, 4bar, 5bar, 6bar), and the membrane pore size is 0.5-0.8 μm (for example, 0.5 μm, 0.6 μm, 0.7 μm, 0.8 μm). The sterilization efficiency of the traditional MF microfiltration sterilization mode is 75-85%, and the MF microfiltration sterilization process under the heating mode is adopted, so that the removal rate of microorganisms can be improved to 95-99.99% when the membrane aperture is 0.5-0.8 mu m at the temperature of 55-60 ℃, and the quality level of the sterilization rate of the skim milk is greatly improved.

(7) Backfilling

In this step, the sterilized cream and the physically sterilized skim milk are mixed in proportion on-line, thereby obtaining a milk product of desired protein content and fat content.

According to an embodiment of the invention, the in-line backfilling is performed at 50-60 deg.C (e.g., at 50 deg.C, 52 deg.C, 55 deg.C, 58 deg.C, 60 deg.C).

(8) Homogenizing

In this step, the sample that will backfill on line carries out the homogenization processing, through the homogenization processing process, can break the fat ball granule in the feed liquid, promotes the homogeneity of feed liquid to prevent the fat come-up condition of product shelf life from producing, and, the milk after the homogeneity can effectual reduction fat oxidation, makes the milk product can ensure to give off fragrant smell.

According to an embodiment of the present invention, the homogenization treatment is performed at a temperature of 50 to 60 ℃ (e.g., at 50 ℃, 52 ℃, 55 ℃, 58 ℃, 60 ℃) and a pressure of 170bar to 230bar (e.g., 170bar, 180bar, 190bar, 200bar, 210bar, 220bar, 230bar), thereby further improving the stability and flavor and taste of the product.

(9) Sterilization treatment

In the step, the product after homogenization treatment is sterilized, and a traditional plate-type or tube-type pasteurization method is adopted, so that pathogenic bacteria in the feed liquid are completely eliminated, and the loss of nutrient components is effectively avoided.

According to an embodiment of the invention, the sterilisation treatment is carried out at 62-65 ℃ for 25-35min, preferably 30min, or at 72-75 ℃ for 12-15 s. Therefore, pathogenic microorganisms can be effectively killed on the premise of reducing the loss of nutrient components as much as possible. The food safety of the product is ensured, the active nutrient components in the product are reserved, and the shelf life of the product is prolonged.

Examples

In this example, a milk product was prepared as follows:

(1) selecting fresh cow milk: healthy cows in a large-scale pasture breeding base are selected, and fresh milk is extracted from the healthy cow breasts by using mechanical milk extracting equipment.

(2) And (4) acceptance: testing the protein, fat, non-fat milk solid, acidity, pH value and total number of bacteria in the fresh milk, wherein the acceptance standard accords with the national standard GB19301 'raw milk', and the qualified raw milk is stored in a cold chain at 2-6 ℃.

(3) Cleaning milk: cold milk purification treatment is carried out on raw milk, a sieve with 80-600 meshes is used for filtration, impurities in the milk are removed, the raw milk is centrifuged and cleaned by a centrifugal milk purifier (Lele company, model: OCM-15), the temperature is controlled at 2-10 ℃, and the raw milk is centrifuged at 4000-6000rpm, so that the impurities in the milk are removed.

(4) And (3) concentrating by using an RO membrane: concentrating raw milk with RO membrane (model: SW8, Alfa Laval company) to obtain trapped liquid, filtering water in raw milk at 4-15 deg.C and 4-6bar under membrane pressure and with membrane pore diameter of 0.001-0.0005 μm, and increasing protein content and fat content of raw milk to make the protein content of raw milk more than 3.2g/100 g.

(5) Degassing: degassing raw milk by a vacuum pump at 55-65 deg.C under-0.04-0.09 Mpa to remove gas and volatile substances.

(6) Separation: separating raw milk into dilute cream and skim milk by a separator (GEA company, model: MSE 100), wherein the separation temperature is 55-60 ℃, the separation speed is 5000-.

(7) High-temperature sterilization of cream: sterilizing the separated dilute cream at the temperature of 115-135 ℃ for 2-15s, and cooling to 30-55 ℃ to obtain the sterilizing liquid.

(8) Physical sterilization: the separated skim milk is connected in series with an MF microfiltration membrane through a degerming separator to remove microorganisms in the skim milk, the temperature of the degerming separator is 55-65 ℃, the centrifugal force is 5000-10000g, the material of the MF microfiltration membrane is a ceramic membrane, the membrane passing temperature is 55-60 ℃, the membrane pressure is 3-6bar, and the membrane aperture is 0.5-0.8 mu m.

(9) And (3) backfilling on line: and (3) carrying out online backfilling on the cream obtained in the step (7) and the skim milk obtained in the step (8), wherein the temperature of the material liquid mixed online is 50-60 ℃, the protein content of the material liquid after the online backfilling is more than or equal to 3.2g/100g, and the fat content is 0.06-0.1g/100g, 0.1-1.5g/100g, 1.5-3.0g/100g, 3.0-3.5g/100g or 3.5-5.0g/100 g.

(10) Homogenizing: and homogenizing the backfilled sample under sterile conditions, wherein the homogenizing temperature is 50-60 ℃, and the pressure is 170-230 bar.

(11) And (3) sterilization: sterilizing the homogenized material liquid at 62-65 deg.C for 25-35min or 72-75 deg.C for 12-15 s. And sterilizing, cooling and filling to obtain the milk product.

TABLE 1 Process parameters

For the conventional milk product preparation method and the above examples 1 to 6, the total number of colonies on day 42 and the contents of furosine, lactoperoxidase, lactoferrin, immunoglobulin and lysozyme in the milk product were measured, and the results are shown in table 2.

The total number of the colonies is detected according to GB 4789.2-2016 total number of the colonies for food safety national standard food microbiological inspection.

The detection results of other active substances are detected by Tianjin Hua detection and authentication company and general standard technical service (Qingdao) Co. Wherein the lactoferrin is detected by high performance liquid chromatography; detecting the furfuryl acid according to the identification method of reconstituted milk in pasteurized milk and UHT sterilized milk; detecting lactoperoxidase by using an enzyme-linked immunosorbent assay; detecting the immunoglobulin by using a liquid phase method or a kit method; lysozyme was detected using the agar diffusion method.

Table 2 shows the effect of different sterilization modes on the product composition

The milk products of the embodiments 1-6 have high content of nutrient active substances and low total number of bacterial colonies at day 42, so that the biological safety of the milk products is greatly improved and the quality guarantee period of the milk is prolonged while the mouthfeel of the milk products is guaranteed. On the whole, the milk obtained by the process of the embodiment 3 has the best quality and relatively higher content of nutrient active substances, ensures high nutrient activity and biological safety of the product, and can fully prolong the shelf life of the product.

In the description herein, references to the description of the term "one embodiment," "some embodiments," "an example," "a specific example," or "some examples," etc., mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above are not necessarily intended to refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Furthermore, various embodiments or examples and features of different embodiments or examples described in this specification can be combined and combined by one skilled in the art without contradiction.

Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention, and that variations, modifications, substitutions and alterations can be made to the above embodiments by those of ordinary skill in the art within the scope of the present invention.

Possibility of industrial application

According to the production process disclosed by the invention, the microbial spoilage risk of the product is reduced through physical sterilization (a sterilizing separator is connected with MF membrane filtration in series), the spore residue risk in the cream is reduced through high-temperature sterilization, and then the pathogenic microorganism residue risk of the product is eliminated through pasteurization, so that high-quality milk products and dairy products meeting the requirements of a large number of consumers can be produced in batches.