Milk capable of retaining native nutrition in milk based on HPP technology and preparation method of milk

Abstract

The invention belongs to the technical field of dairy products, and particularly relates to milk capable of reserving native nutrition in milk based on an HPP technology and a preparation method of the milk. The milk is produced by dairy cows fed with rumen bypass protection type Omega-3 feed and is prepared by adopting an ultrahigh pressure treatment technology for sterilization and fresh keeping. The rumen protection type Omega-3 feed is a mixture formed by mixing total mixed ration and Omega-3 microcapsules according to the mass ratio of 100: (1-10). The Omega-3 microcapsule is prepared from the following raw materials: seaweed meal and / or fish oil; the technical conditions of the ultrahigh pressure treatment are as follows: the pressure is 500-600 MPa, the pressure holding time is 3-6 minutes, and the temperature is 4-15 DEG C; in the milk, the content of the EPA and the DHA ranges from 36.2 mg / 100 mL to 47.4 mg / 100 mL, and the retention rate ranges from 94.8% to 97.1%; the retention rate of the active immune globulin is between 90% and 92%.

Description

Technical Field

[0001] This invention belongs to the field of dairy product technology, and specifically relates to a milk that retains the original nutrients in milk based on HPP technology and its preparation method. Background Technology

[0002] Traditional Omega-3-rich milk is often produced by directly adding microalgae oil or fish oil exogenously. This method presents challenges related to oxidation, absorption, and flavor, and its labeling is limited; it's often labeled as "non-natural" and can only be described as "added DHA," resulting in low market value. Traditional heat sterilization technologies (such as pasteurization and UHT) require heating to achieve sterilization, which significantly damages heat-sensitive EPA, DHA, as well as active substances like natural immunoglobulins and lactoperoxidase, producing a "cooked" taste and affecting the milk's natural flavor. EPA and DHA are polyunsaturated fatty acids with multiple unsaturated double bonds in their molecular structure, making them chemically reactive and prone to oxidative rancidity. Therefore, their content gradually decreases over shelf life.

[0003] Therefore, the art seeks a dairy product with increased natural EPA and DHA content and a method for its preparation. Summary of the Invention

[0004] The purpose of this invention is to provide a milk and its preparation method based on HPP (High Pressure Processing) technology that preserves the original nutrients in milk, thereby increasing the content of natural EPA and DHA in dairy cow milk fat and thus maximizing the preservation of the natural activity of substances such as Omega-3 fatty acids.

[0005] Therefore, the present invention provides the following technical solution.

[0006] One aspect of the present invention provides milk that retains the original nutrients in milk based on HPP technology, wherein the milk is produced by dairy cows fed with rumen-protective Omega-3 feed and is prepared by sterilization and preservation using ultra-high pressure processing technology.

[0007] In a preferred embodiment of the present invention, the rumen-protective Omega-3 feed is a mixture of total mixed ration and Omega-3 microcapsules at a mass ratio of 100:1-10.

[0008] In a preferred embodiment of the present invention, the raw material composition of the Omega-3 microcapsules includes seaweed powder and / or fish oil.

[0009] In a preferred embodiment of the present invention, the ultra-high pressure treatment conditions are: pressure of 500-600MPa, pressure holding time of 3-6min, and temperature of 4-15℃.

[0010] In a preferred embodiment of the present invention, the content of EPA+DHA in the milk is between 36.2 mg / 100 mL and 47.4 mg / 100 mL, and the retention rate is between 94.8% and 97.1%; the retention rate of the active immunoglobulin is between 90% and 92%.

[0011] A second aspect of the present invention provides a method for preparing milk that retains the original nutrients in milk based on HPP technology, the method comprising the following steps: S1: Obtain raw milk from dairy cows fed with rumen-protected Omega-3 feed; S2: The obtained raw milk is homogenized and degassed in sequence, and then packaged to obtain packaged milk; S3: The packaged milk is subjected to ultra-high pressure treatment to obtain the finished milk product.

[0012] In a preferred embodiment of the present invention, in step S1, the rumen-protective Omega-3 feed is a mixture of total mixed ration and Omega-3 microcapsules at a mass ratio of 100:1-10; The raw materials of the Omega-3 microcapsules include seaweed powder and / or fish oil.

[0013] In a preferred embodiment of the present invention, in step S1, the formula of the total mixed ration is as follows: 35%-40% corn silage, 15%-20% alfalfa hay, 5%-10% oat hay, 20%-25% flaked corn, 8%-12% soybean meal, 1-2% vitamin and mineral package (containing vitamins A, D, E, calcium, phosphorus, magnesium, zinc, etc., salt, baking soda), 1-2% molasses, and 0.5%-1% palm fat powder.

[0014] In a preferred embodiment of the present invention, the preparation process of the Omega-3 microcapsules is as follows: S11: Disperse fish oil or microalgae powder in an acidic chitosan solution containing vitamin E at a mass-volume ratio of 1g:30-50ml, and then emulsify to obtain an emulsion. S12: Mix the obtained emulsion with a sodium alginate solution with a mass concentration of 5-10wt% at a volume ratio of 1:5-10, stir, and then add calcium chloride solution with a volume of 40-60% of the sodium alginate solution to solidify and obtain gel microspheres. S13: Freeze-dry the obtained gel microspheres to obtain microcapsule particles.

[0015] In a preferred embodiment of the present invention, in step S11, the preparation process of the acidic chitosan solution containing vitamin E is as follows: dissolve chitosan in a 1-2% aqueous acetic acid solution to obtain an acidic chitosan solution with a concentration of 1-3 wt%, and add vitamin E at 1-3% of the mass of chitosan, and stir to dissolve.

[0016] In a preferred embodiment of the present invention, in step S11, the emulsification conditions are: rotation speed 10,000-15,000 rpm, time 3-5 min.

[0017] In a preferred embodiment of the present invention, in step S12, the stirring conditions are: temperature 25-30°C, time 15-30 min.

[0018] In a preferred embodiment of the present invention, in step S12, the concentration of the calcium chloride solution is 2.0%-5.0%.

[0019] In a preferred embodiment of the present invention, in step S12, the curing conditions are: temperature 20-30°C, time 20-30 min.

[0020] In a preferred embodiment of the present invention, in step S13, the freeze-drying process is as follows: the gel microspheres are first rapidly frozen at -40°C to -80°C for 6-12 hours to obtain a frozen sample; The frozen samples were subjected to primary drying for 24-48 hours under the conditions of -50°C to -60°C in a condenser and a vacuum degree of <10 Pa. The temperature was gradually increased to 25-30°C and maintained for about 8-12 hours to obtain microcapsule particles.

[0021] In a preferred embodiment of the present invention, the homogenization conditions in step S2 are: temperature: 10-15℃, homogenization pressure: first-stage pressure 18-25 MPa, second-stage pressure 3-5 MPa; In a preferred embodiment of the present invention, in step S2, the degassing conditions are: pressure of -0.05 MPa to -0.07 MPa and time of 10s to 30s.

[0022] In a preferred embodiment of the present invention, in step S3, the ultra-high pressure treatment conditions are: pressure of 500-600 MPa, pressure holding time of 3-6 min, and temperature of 4-15℃.

[0023] By employing the above technical solution, the present invention has at least the following advantages: (1) This invention is based on precise nutritional regulation of milk production and adopts rumen protection technology to precisely regulate the nutrition of dairy cow diets. Feed ingredients such as microalgae powder and fish oil with high Omega-3 precursors that have been encapsulated are made into rumen-protected feed and fed to dairy cows to increase the content of native EPA+DHA in raw milk.

[0024] (2) The present invention uses vacuum degassing + HPP ultra-high pressure treatment technology to replace the original pasteurization and UHT sterilization methods, which improves the retention rate of heat-sensitive EPA+DHA and other active nutrients, and obtains a purer flavor and taste. Sensory evaluation results show that the milk obtained by the present invention has no cooking taste, no off-flavor, and prominent milk flavor. The overall acceptance is significantly higher than that of traditional heat-sterilized products, and the flavor is comparable to that of commercially available fresh milk, which meets the market demand for "clean label" and "natural flavor".

[0025] (3) The present invention uses high-barrier packaging materials to reduce the oxidative loss of EPA+DHA during the shelf life. After the milk obtained by the present invention is stored at 4°C for 28 days, the EPA+DHA retention rate is still higher than 93%, the peroxide value is lower than 2.5 meq / kg, and the sensory flavor is well maintained, showing excellent oxidative stability and shelf life adaptability, which is suitable for the development and promotion of long-acting functional dairy products.

[0026] The above description is merely an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention and to implement it in accordance with the contents of the specification, the preferred embodiments of the present invention are described in detail below. Detailed Implementation

[0027] To make the technical means, creative features, achieved objectives, and effects of this invention readily understandable, the technical solutions in the embodiments of this invention will be clearly and completely described below in conjunction with the embodiments of this invention. Obviously, the described embodiments are merely some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0028] The detection methods mentioned in the following examples are all based on the national standard GB 5009.168-2016 National Food Safety Standard - Determination of Fatty Acids in Food.

[0029] The total mixed ration (TMR) formulation mentioned in the following examples is as follows: 40% corn silage, 20% alfalfa hay, 5% oat hay, 20% flaked corn, 10% soybean meal, 2% vitamin and mineral packet (containing vitamins A, D, E, calcium, phosphorus, magnesium, zinc, salt, and baking soda), 2% molasses, and 1% palm fat powder.

[0030] Example 1: Preparation of Milk I Fish oil was dispersed in an acidic chitosan solution containing vitamin E at a mass-to-volume ratio of 1 g:40 ml (chitosan was dissolved in a 2% acetic acid aqueous solution to obtain a 2 wt% chitosan acidic solution, and then 1% of vitamin E by weight of chitosan was added and stirred until dissolved). The solution was then emulsified at 15,000 rpm for 5 min to obtain an emulsion. The resulting emulsion was mixed with a 7.5 wt% sodium alginate solution at a volume ratio of 1:8, and then stirred at 25°C for 25 min. A 3.5% calcium chloride solution (50% of the volume of the sodium alginate solution) was then added for solidification to obtain gel microspheres. The obtained gel microspheres were first rapidly frozen at -40°C for 9 h to obtain frozen samples. The frozen samples were then subjected to primary drying at -55°C and a vacuum degree <10 Pa in a condenser for 36 h. Finally, the temperature was gradually lowered to 25°C and maintained for approximately 10 h to obtain microcapsule particles.

[0031] Thirty healthy Holstein dairy cows in mid-lactation (80-120 days postpartum) were selected and fed the rumen-protective Omega-3 feed (microencapsulated particles:TMR mass ratio = 5:100) described in this invention for 28 consecutive days. On the morning of the 29th day, a mixed sample of raw milk was collected during milking and rapidly cooled to 4°C. Testing revealed that the total content of native EPA and DHA in this batch of raw milk was 38 mg / 100 mL.

[0032] The raw milk was pretreated at a low temperature (≤10℃). First, it was centrifuged at 6℃ and 7000 rpm using a tubular centrifuge to separate skim milk and cream with a fat content of approximately 38%. Then, based on real-time fat detection results, the cream was added back to the skim milk in a specific ratio using an automated mixing system, precisely standardizing the fat content to 3.5%, resulting in homogeneous and stable pretreated raw milk. The pretreated raw milk was then homogenized in two stages at 12℃ (first stage pressure 20 MPa, second stage pressure 5 MPa), followed by degassing at -0.06 MPa for 20 seconds. It was then aseptically filled into 500 mL high-barrier (with EVOH layer) PE plastic bottles and sealed to obtain packaged milk. The packaged milk was then subjected to ultra-high pressure (HPP) treatment at 550 MPa for 4.5 min, with the temperature maintained at 6℃, to obtain the final product.

[0033] The EPA+DHA content was measured at 36.9 mg / 100 mL, with a calculated retention rate of 97.1%. Active immunoglobulins: 92% retention.

[0034] Example 2: Preparation of Milk II Fish oil was dispersed in an acidic chitosan solution containing vitamin E at a mass-to-volume ratio of 1 g:30 ml (chitosan was dissolved in a 2% acetic acid aqueous solution to obtain a 1 wt% chitosan acidic solution, and then 3% of vitamin E by weight of chitosan was added and stirred until dissolved). The solution was then emulsified at 10,000 rpm for 5 min to obtain an emulsion. The resulting emulsion was mixed with a 10 wt% sodium alginate solution at a volume ratio of 1:5, and then stirred at 25°C for 30 min. A 2.0% calcium chloride solution (60% of the volume of the sodium alginate solution) was then added for solidification to obtain gel microspheres. The obtained gel microspheres were first rapidly frozen at -80°C for 6 h to obtain frozen samples. The frozen samples were then subjected to primary drying at -50°C and a vacuum degree <10 Pa in a condenser for 48 h. Finally, the temperature was gradually lowered to 25°C and maintained for approximately 8 h to obtain microcapsule particles.

[0035] Thirty healthy Holstein dairy cows in mid-lactation (80-120 days postpartum) were selected and fed the rumen-protective Omega-3 feed (microencapsulated particles:TMR mass ratio = 10:100) described in this invention for 28 consecutive days. On the morning of the 29th day, a mixed sample of raw milk was collected during milking and rapidly cooled to 4°C. Testing revealed that the total content of native EPA and DHA in this batch of raw milk was 37.6 mg / 100 mL.

[0036] The raw milk was pretreated at a low temperature (≤10℃). First, it was centrifuged at 6℃ and 7000 rpm using a tubular centrifuge to separate skim milk and cream with a fat content of approximately 38%. Then, based on real-time fat detection results, the cream was added back to the skim milk in a specific ratio using an automated mixing system, precisely standardizing the fat content to 3.5%, resulting in a homogeneous and stable pretreated raw milk. The pretreated raw milk was then homogenized in two stages at 10℃ (first stage pressure 18 MPa, second stage pressure 5 MPa), followed by degassing at -0.07 MPa for 10 seconds. It was then aseptically filled into 500 mL high-barrier (with EVOH layer) PE plastic bottles and sealed to obtain packaged milk. The packaged milk was then subjected to ultra-high pressure (HPP) treatment at 500 MPa for 3.5 min, with the temperature maintained at 8℃, to obtain the final product.

[0037] The EPA+DHA content was measured at 36.2 mg / 100 mL, with a calculated retention rate of 96.3%. Active immunoglobulins: 91% retention.

[0038] Example 3: Preparation of Milk III Fish oil was dispersed in an acidic chitosan solution containing vitamin E at a mass-to-volume ratio of 1 g:50 ml (chitosan was dissolved in a 1% acetic acid aqueous solution to obtain a 3 wt% chitosan acidic solution, and then 1% of vitamin E by weight of chitosan was added and stirred until dissolved). The solution was then emulsified at 15,000 rpm for 3 min to obtain an emulsion. The resulting emulsion was mixed with a 5 wt% sodium alginate solution at a volume ratio of 1:10, and then stirred at 30°C for 15 min. A 5.0% calcium chloride solution (40% of the volume of the sodium alginate solution) was then added for solidification to obtain gel microspheres. The obtained gel microspheres were first rapidly frozen at -40°C for 12 h to obtain frozen samples. The frozen samples were then subjected to primary drying at -60°C and a vacuum degree <10 Pa in a condenser for 24 h. Finally, the temperature was gradually lowered to 25°C and maintained for approximately 12 h to obtain microcapsule particles.

[0039] Thirty healthy Holstein dairy cows in mid-lactation (80-120 days postpartum) were selected and fed the rumen-protective Omega-3 feed (microencapsulated particles:TMR mass ratio = 3:100) described in this invention for 28 consecutive days. On the morning of the 29th day, a mixed sample of raw milk was collected during milking and rapidly cooled to 4°C. Testing revealed that the total content of native EPA and DHA in this batch of raw milk was 37.8 mg / 100 mL.

[0040] The raw milk was pretreated at a low temperature (≤10℃). First, it was centrifuged at 6℃ and 7000 rpm using a tubular centrifuge to separate skim milk and cream with a fat content of approximately 38%. Then, based on real-time fat detection results, the cream was added back to the skim milk in a specific ratio using an automated mixing system, precisely standardizing the fat content to 3.5%, resulting in a homogeneous and stable pretreated raw milk. The pretreated raw milk was then homogenized in two stages at 12℃ (first stage pressure 20 MPa, second stage pressure 5 MPa); degassed under a vacuum of -0.05 MPa, and aseptically filled into 500 mL high-barrier (with EVOH layer) PE plastic bottles and sealed to obtain packaged milk. The packaged milk was then subjected to ultra-high pressure (HPP) treatment at 600 MPa for 5.5 min, with the temperature maintained at 8℃, to obtain the final product.

[0041] The EPA+DHA content was measured at 36.5 mg / 100 mL, with a calculated retention rate of 96.6%. Active immunoglobulins: 90% retention.

[0042] Example 4: Preparation of Bovine Milk IV Fish oil was dispersed in an acidic chitosan solution containing vitamin E at a mass-to-volume ratio of 1 g:40 ml (chitosan was dissolved in a 2% acetic acid aqueous solution to obtain a 3 wt% chitosan acidic solution, and then 2% of vitamin E by weight of chitosan was added and stirred until dissolved). The solution was then emulsified at 15,000 rpm for 3 min to obtain an emulsion. The resulting emulsion was mixed with a 6 wt% sodium alginate solution at a volume ratio of 1:9, and stirred at 25°C for 30 min. Then, 40-60% of the volume of the sodium alginate solution (4.0% concentration) was added for solidification to obtain gel microspheres. The obtained gel microspheres were first rapidly frozen at -80°C for 12 h to obtain frozen samples. The frozen samples were then subjected to primary drying at -50°C and a vacuum degree <10 Pa in a condenser for 24 h. Finally, the temperature was gradually lowered to 25°C and maintained for approximately 10 h to obtain microcapsule particles.

[0043] Thirty healthy Holstein dairy cows in mid-lactation (80-120 days postpartum) were selected and fed the rumen-protective Omega-3 feed (microencapsulated particles:TMR mass ratio = 1:100) described in this invention for 28 consecutive days. On the morning of the 29th day, a mixed sample of raw milk was collected during milking and rapidly cooled to 4°C. Testing revealed that the total content of native EPA and DHA in this batch of raw milk was 50 mg / 100 mL.

[0044] The raw milk was pretreated at a low temperature (≤10℃). First, it was centrifuged at 6℃ and 7000 rpm using a tubular centrifuge to separate skim milk and cream with a fat content of approximately 38%. Then, based on real-time fat detection results, the cream was added back to the skim milk in a specific ratio using an automated mixing system, precisely standardizing the fat content to 3.5%, resulting in a homogeneous and stable pretreated raw milk. The pretreated raw milk was then homogenized in two stages at 15℃ (first stage pressure 25 MPa, second stage pressure 3 MPa); degassed under a vacuum of -0.06 MPa, and aseptically filled into 500 mL high-barrier (with EVOH layer) PE plastic bottles and sealed to obtain packaged milk. The packaged milk was then subjected to ultra-high pressure (HPP) treatment at a pressure of 540 MPa for 4.0 min, with the temperature maintained at 4℃, to obtain the final product.

[0045] The EPA+DHA content was measured at 47.4 mg / 100 mL, with a calculated retention rate of 94.8%. Active immunoglobulins: 91.5% retention.

[0046] Comparative Example 1: Preparation of Milk V Fish oil was dispersed in an acidic chitosan solution containing vitamin E at a mass-to-volume ratio of 1 g:40 ml (chitosan was dissolved in a 2% acetic acid aqueous solution to obtain a 2 wt% chitosan acidic solution, and then 1% of vitamin E by weight of chitosan was added and stirred until dissolved). The solution was then emulsified at 15,000 rpm for 5 min to obtain an emulsion. The resulting emulsion was mixed with a 7.5 wt% sodium alginate solution at a volume ratio of 1:8, and then stirred at 25°C for 25 min. A 3.5% calcium chloride solution (50% of the volume of the sodium alginate solution) was then added for solidification to obtain gel microspheres. The obtained gel microspheres were first rapidly frozen at -40°C for 9 h to obtain frozen samples. The frozen samples were then subjected to primary drying at -55°C and a vacuum degree <10 Pa in a condenser for 36 h. Finally, the temperature was gradually lowered to 25°C and maintained for approximately 10 h to obtain microcapsule particles.

[0047] Thirty healthy Holstein dairy cows in mid-lactation (80-120 days postpartum) were selected and fed the rumen-protective Omega-3 feed (microencapsulated particles:TMR mass ratio = 5:100) described in this invention for 28 consecutive days. On the morning of the 29th day, a mixed sample of raw milk was collected during milking and rapidly cooled to 4°C. Testing revealed that the total content of native EPA and DHA in this batch of raw milk was 38 mg / 100 mL.

[0048] The raw milk was pretreated at a low temperature (≤10℃). First, it was centrifuged at 6℃ and 7000 rpm using a tubular centrifuge to separate skim milk and cream with a fat content of approximately 38%. Then, based on real-time fat detection results, the cream was added back to the skim milk in a specific ratio using an automated mixing system, precisely standardizing the fat content to 3.5%, resulting in homogeneous and stable pretreated raw milk. Next, the pretreated raw milk underwent two-stage homogenization at 12℃ (first stage pressure 20 MPa, second stage pressure 5 MPa), followed by ultra-high temperature (UHT) sterilization at 137℃ for 4 seconds. Finally, it was aseptically filled into 500 mL high-barrier (with EVOH layer) PE plastic bottles and sealed to obtain the packaged milk, the final product.

[0049] The EPA+DHA content was measured at 24.7 mg / 100 mL, with a retention rate of 65%. Active immunoglobulins were retained at 40%. The product exhibited a distinct "cooked" flavor.

[0050] Comparative Example 2: Preparation of Milk VI Fish oil was dispersed in an acidic chitosan solution containing vitamin E at a mass-to-volume ratio of 1 g:40 ml (chitosan was dissolved in a 2% acetic acid aqueous solution to obtain a 2 wt% chitosan acidic solution, and then 1% of vitamin E by weight of chitosan was added and stirred until dissolved). The solution was then emulsified at 15,000 rpm for 5 min to obtain an emulsion. The resulting emulsion was mixed with a 7.5 wt% sodium alginate solution at a volume ratio of 1:8, and then stirred at 25°C for 25 min. A 3.5% calcium chloride solution (50% of the volume of the sodium alginate solution) was then added for solidification to obtain gel microspheres. The obtained gel microspheres were first rapidly frozen at -40°C for 9 h to obtain frozen samples. The frozen samples were then subjected to primary drying at -55°C and a vacuum degree <10 Pa in a condenser for 36 h. Finally, the temperature was gradually lowered to 25°C and maintained for approximately 10 h to obtain microcapsule particles.

[0051] Thirty healthy Holstein dairy cows in mid-lactation (80-120 days postpartum) were selected and fed the rumen-protective Omega-3 feed (microencapsulated particles:TMR mass ratio = 5:100) described in this invention for 28 consecutive days. On the morning of the 29th day, a mixed sample of raw milk was collected during milking and rapidly cooled to 4°C. Testing revealed that the total content of native EPA and DHA in this batch of raw milk was 38 mg / 100 mL.

[0052] The raw milk was pretreated at a low temperature (≤10℃). First, it was centrifuged at 6℃ and 7000 rpm using a tubular centrifuge to separate skim milk and cream with a fat content of approximately 38%. Then, based on real-time fat detection results, the cream was added back to the skim milk in a specific ratio using an automated mixing system, precisely standardizing the fat content to 3.5%, resulting in homogeneous and stable pretreated raw milk. The pretreated raw milk was then homogenized in two stages at 12℃ (first stage pressure 20 MPa, second stage pressure 5 MPa), followed by pasteurization at 75℃ for 15 seconds. Finally, it was aseptically filled into 500 mL high-barrier (with EVOH layer) PE plastic bottles and sealed to obtain the packaged milk, the final product.

[0053] The EPA+DHA content was measured at 28.5 mg / 100 mL, with a calculated retention rate of 75%. Active immunoglobulins were retained at 55%. The product flavor was superior to UHT, but a noticeable heat-processed flavor remained.

[0054] Comparative Example 3: Preparation of Milk VII Thirty healthy Holstein dairy cows in mid-lactation (80-120 days postpartum) were selected and fed a TMR diet for 28 consecutive days. On the morning of the 29th day, a mixed sample of raw milk was collected during milking and rapidly cooled to 4°C. Testing revealed no significant levels of native EPA and DHA in this batch of raw milk.

[0055] The raw milk was pretreated at a low temperature (≤10℃). First, it was centrifuged at 6℃ and 7000 rpm using a tubular centrifuge to separate skim milk and cream with a fat content of approximately 38%. Then, based on real-time fat detection results, the cream was added back to the skim milk in a specific ratio using an automated mixing system, precisely standardizing the fat content to 3.5%, resulting in homogeneous and stable pretreated raw milk. The pretreated raw milk was then homogenized in two stages at 12℃ (first stage pressure 20 MPa, second stage pressure 5 MPa), followed by degassing at -0.06 MPa for 20 seconds. It was then aseptically filled into 500 mL high-barrier (with EVOH layer) PE plastic bottles and sealed to obtain packaged milk. The packaged milk was then subjected to ultra-high pressure (HPP) treatment at 550 MPa for 4.5 min, with the temperature maintained at 6℃, to obtain the final product.

[0056] EPA+DHA levels were not significantly detected. Active immunoglobulins: 57% retained.

[0057] Comparative Example 4: Preparation of Milk VIII Thirty healthy Holstein dairy cows in mid-lactation (80-120 days postpartum) were selected and fed a rumen-protective Omega-3 diet (microencapsulated pellets: fish oil mass ratio = 5:100) for 28 consecutive days. On the morning of the 29th day, a mixed sample of raw milk was collected during milking and rapidly cooled to 4°C. Testing revealed that the total content of native EPA and DHA in this batch of raw milk was 17.6 mg / 100mL.

[0058] The raw milk was pretreated at a low temperature (≤10℃). First, it was centrifuged at 6℃ and 7000 rpm using a tubular centrifuge to separate skim milk and cream with a fat content of approximately 38%. Then, based on real-time fat detection results, the cream was added back to the skim milk in a specific ratio using an automated mixing system, precisely standardizing the fat content to 3.5%, resulting in homogeneous and stable pretreated raw milk. The pretreated raw milk was then homogenized in two stages at 12℃ (first stage pressure 20 MPa, second stage pressure 5 MPa), followed by degassing at -0.06 MPa for 20 seconds. It was then aseptically filled into 500 mL high-barrier (with EVOH layer) PE plastic bottles and sealed to obtain packaged milk. The packaged milk was then subjected to ultra-high pressure (HPP) treatment at 550 MPa for 4.5 min, with the temperature maintained at 6℃, to obtain the final product.

[0059] The EPA+DHA content was measured at 4.2 mg / 100 mL, with a retention rate of 23.9%. Active immunoglobulins: 19.8% retention.

[0060] Table 1 summarizes the milk performance tests of each example and comparative example.

[0061] Table 1 ; As shown in Table 1 above, the HPP non-thermal sterilization technology combined with degassing process used in this invention is significantly superior to traditional thermal sterilization technology in terms of retention of key active nutrients and flavor preservation. In addition, compared with the direct use of fish oil, the rumen-protective Omega-3 feed of this invention produces milk with significantly higher EPA+DHA content and significantly higher retention rate.

[0062] Test Example 1: Shelf-life stability test To verify the oxidative stability of EPA+DHA in milk prepared by the method described in this invention during storage, the finished products of Example 1 (milk I) and Comparative Examples 1-4 (milk V-VIII) were placed under refrigeration at 4°C for a storage test lasting 28 days. Samples were taken on days 0, 7, 14, 21, and 28, and the EPA+DHA content, peroxide value (POV), and sensory flavor changes were measured. The results are shown in Table 2.

[0063] Table 2 Shelf-life stability test results ; As shown in Table 2, Example 1 of this invention (combining rumen-protected feed + HPP + deaeration) maintained an EPA+DHA retention rate of over 93% and a POV value consistently below 2.5 meq / kg during a 28-day storage period, exhibiting excellent sensory flavor. Comparative Examples 1 (UHT) and 2 (pasteurized) suffered from low initial EPA+DHA retention rates due to heat processing, and accelerated oxidation during storage, resulting in rapid flavor deterioration. Comparative Example 3 (ordinary HPP milk), while lacking a cooked flavor, offered no nutritional enhancement due to the absence of Omega-3 sources. Comparative Example 4 (directly added fish oil + HPP), lacking rumen protection technology, had extremely low EPA+DHA content and rapid oxidation, leading to significant flavor deterioration. In summary, this invention, through a systematic process of "source nutrient regulation + non-thermal sterilization + deaeration + high-barrier packaging," achieves high stability and excellent property maintenance of highly active nutritional milk during its shelf life, demonstrating significant technological advancement and market application value.

[0064] Experiment Example 2: Sensory Evaluation Experiment To objectively evaluate the flavor quality of the milk obtained in this invention, a quantitative descriptive analysis method combined with the triangulation method was used to conduct blind evaluations of Example 1 (milk I) and Comparative Examples 1-4 (milk V-VIII). Ten sensory-trained evaluators scored the samples, and the evaluation indicators included "cooking flavor intensity", "milk flavor intensity", "off-flavor intensity (such as oxidized flavor, fishy flavor)" and "overall acceptability". The results are shown in Table 3.

[0065] Table 3. Sensory evaluation test results ; As shown in Table 3, Example 1 (milk I) scored extremely low in terms of cooking flavor and off-flavor intensity, with a prominent milky aroma and the highest overall acceptance (8.6 points), indicating that its flavor is close to that of raw milk and has no undesirable heat treatment or oxidative flavor. Comparative Example 1 (UHT treatment) showed significant cooking and off-flavors, with the lowest overall acceptance (3.9 points), indicating severe flavor deterioration. Comparative Example 2 (pasteurization) showed improvement, but still had a noticeable heat treatment flavor and a slight oxidative flavor, with a moderate overall acceptance (6.5 points). Comparative Example 3 (ordinary HPP milk) had no heat treatment flavor, but its milky aroma was slightly lower than that of Example 1, with good overall acceptance (7.8 points). Comparative Example 4 (direct addition of fish oil + HPP) did not use rumen protection technology, resulting in prominent fishy and oxidative flavors and poor overall acceptance (4.1 points). In summary, this invention, through rumen-protected feed + HPP non-thermal sterilization + degassing process, achieves high nutrient retention while maximizing the preservation of the natural flavor of milk, which is significantly superior to traditional heat-sterilized and exogenous additive products.

[0066] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the methods and techniques disclosed above without departing from the scope of the present invention to create equivalent embodiments. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A type of milk that retains the original nutrients in milk based on HPP technology, characterized in that, The milk is produced by dairy cows fed with rumen-protected Omega-3 feed and is prepared by sterilization and preservation using ultra-high pressure processing technology. The rumen-protective Omega-3 feed is a mixture of total mixed ration and Omega-3 microcapsules at a mass ratio of 100:1-10; The raw material composition of the Omega-3 microcapsules includes seaweed powder and / or fish oil; The ultra-high pressure processing technical conditions are: pressure of 500-600 MPa, pressure holding time of 3-6 min, and temperature of 4-15℃; The milk contains EPA+DHA at a concentration between 36.2 mg / 100 mL and 47.4 mg / 100 mL, with a retention rate between 94.8% and 97.1%; the active immunoglobulin has a retention rate between 90% and 92%.

2. The method for preparing milk based on HPP technology to retain the original nutrients in milk according to claim 1, characterized in that, The method includes the following steps: S1: Obtain raw milk from dairy cows fed with rumen-protected Omega-3 feed; S2: The obtained raw milk is homogenized and degassed in sequence, and then packaged to obtain packaged milk; S3: The packaged milk is subjected to ultra-high pressure treatment to obtain the finished milk product.

3. The preparation method according to claim 2, characterized in that, In step S1, the rumen-protective Omega-3 feed is a mixture of total mixed ration and Omega-3 microcapsules at a mass ratio of 100:1-10; The raw materials of the Omega-3 microcapsules include seaweed powder and / or fish oil.

4. The preparation method according to claim 2, characterized in that, The total mixed ration (TMR) formula is as follows: 35%-40% corn silage, 15%-20% alfalfa hay, 5%-10% oat hay, 20%-25% flaked corn, 8%-12% soybean meal, 1-2% vitamin and mineral supplement (containing vitamins A, D, E, calcium, phosphorus, magnesium, zinc, salt, and baking soda), 1-2% molasses, and 0.5%-1% palm fat meal.

5. The preparation method according to claim 3, characterized in that, The preparation process of the Omega-3 microcapsules is as follows: S11: Disperse fish oil or microalgae powder in an acidic chitosan solution containing vitamin E at a mass-volume ratio of 1g:30-50ml, and then emulsify to obtain an emulsion. S12: Mix the obtained emulsion with a sodium alginate solution with a mass concentration of 5-10wt% at a volume ratio of 1:5-10, stir, and then add calcium chloride solution with a volume of 40-60% of the sodium alginate solution to solidify and obtain gel microspheres. S13: Freeze-dry the obtained gel microspheres to obtain microcapsule particles.

6. The preparation method according to claim 5, characterized in that, In step S11, The preparation process of the vitamin E-containing chitosan acidic solution is as follows: dissolve chitosan in a 1-2% acetic acid aqueous solution to obtain a chitosan acidic solution with a concentration of 1-3 wt%, and add vitamin E at 1-3% of the chitosan mass, and stir to dissolve. The emulsification conditions are: rotation speed 10,000-15,000 rpm, time 3-5 min.

7. The preparation method according to claim 5, characterized in that, In step S12, the stirring conditions are: temperature 25-30℃, time 15-30min; The concentration of the calcium chloride solution is 2.0%-5.0%; The curing conditions are: temperature 20-30℃, time 20-30min.

8. The preparation method according to claim 5, characterized in that, In step S13, the freeze-drying process is as follows: the gel microspheres are first rapidly frozen at -40°C to -80°C for 6-12 hours to obtain a frozen sample; The frozen samples were subjected to primary drying for 24-48 hours under the conditions of -50°C to -60°C in a condenser and a vacuum degree of <10 Pa. The temperature was gradually increased to 25-30°C and maintained for about 8-12 hours to obtain microcapsule particles.

9. The preparation method according to claim 2, characterized in that, In step S2, the homogenization conditions are: temperature: 10-15℃, homogenization pressure: first-stage pressure 18-25 MPa, second-stage pressure 3-5 MPa; The degassing conditions are: pressure of -0.05 MPa to -0.07 MPa, and time of 10s to 30s.

10. The preparation method according to claim 2, characterized in that, In step S3, the ultra-high pressure treatment conditions are: pressure of 500-600 MPa, pressure holding time of 3-6 min, and temperature of 4-15℃.