Production method of sheep milk and sheep milk

Abstract

The invention relates to the technical field of dairy products, and provides a production method of sheep milk and the sheep milk. The method comprises the following steps: filtering a sheep milk raw material, and collecting filtrate; performing high-pressure microjet homogenization treatment on the filtrate to obtain a pre-sterilized product; and performing cold plasma treatment on the pre-sterilized product to obtain the sheep milk. According to the method disclosed by the invention, not only is the shelf life of the sheep milk prolonged, but also functional factors in the sheep milk are effectively reserved, and the damage of high-temperature sterilization to the functional factors is avoided, so that the quality of a sheep milk product is remarkably improved.

Description

Technical Field

[0001] The present invention relates to the technical field of dairy products, and in particular to a method for producing sheep milk and sheep milk. Background Art

[0002] Sheep milk is rich in nutrition and its composition is close to breast milk. It has good effects on the human body and is known as the "king of milk". The basic nutritional composition of sheep milk is affected by factors such as breed, season, lactation period, breast health, feeding conditions, and environment. The nutritional value of sheep milk is quite high. Compared with goat milk and cow milk, sheep milk has higher protein and fat content and can better meet people's nutritional needs. Sheep milk contains a variety of antibacterial, immunomodulatory and antioxidant bioactive substances, such as lactoferrin, bioactive peptides, conjugated linoleic acid, epidermal growth factor, etc. Among them, the lactoferrin content in sheep milk reaches 0.7~0.9 g / kg, the conjugated linoleic acid content is 1.6%, and the calorific value is 5932 kJ / kg. Therefore, sheep milk and its derivative products have high dietary value. The protein, fat, and solid content of sheep milk are significantly higher than those of goat milk and Holstein milk, and it is a good source of energy.

[0003] Since sheep milk is very sensitive to temperature, excessively high temperatures will cause the active ingredients in it to lose their activity. Therefore, there is an urgent need to develop a processing method that can both extend the shelf life of sheep milk and produce it under low temperature conditions. Summary of the invention

[0004] The present invention aims to solve at least one of the technical problems existing in the prior art to at least a certain extent.

[0005] It should be noted that the present invention is based on the inventor's discovery and understanding of the following facts and problems: At present, the mainstream products in my country's liquid milk market are high-temperature short-time sterilized milk and ultra-high temperature instantaneous sterilized milk. In order to extend the shelf life of such products, they must go through high-temperature links during processing, which can easily cause adverse changes in liquid milk, such as color changes, decreased emulsification stability, denaturation of heat-sensitive active proteins and functional factors, etc., which in turn lead to precipitation formation during the shelf life of the product, loss of biological activity of functional factors, and a decline in the nutritional value of dairy products. Improper heat processing will affect the stability of the milk fat globule membrane, causing different degrees of denaturation of milk fat globule membrane proteins and phospholipids, significantly reducing the inhibitory effect on cancer cell proliferation. The sterilization temperature of pasteurized milk is slightly lower, but it has the shortcoming of a short shelf life (usually 5-7 days). High-pressure sterilized milk adopts ultra-high pressure sterilization, which will cause protein denaturation in milk and the precipitation of flocs.

[0006] In view of this, the inventor found in the research process that although high-pressure microjet homogenization can be used alone to homogenize sheep milk and play a certain bactericidal role, its bactericidal effect is limited, resulting in a high total colony count of prepared sheep milk and the presence of peculiar smell. To solve this problem, the inventor introduced cold plasma treatment after high-pressure microjet homogenization. Cold plasma can significantly improve the inactivation rate of bacteria under non-thermal conditions, and at the same time increase the phosphorylation degree of casein in sheep milk, and enhance its functional properties, such as water holding capacity, solubility, foaming ability and stability. Therefore, the present invention combines high-pressure microjet homogenization with cold plasma sterilization technology to complete the homogenization, pre-sterilization and sterilization of sheep milk at room temperature. This method not only extends the shelf life of sheep milk, but also effectively retains the functional factors in sheep milk, avoids the destruction of these functional factors by high-temperature sterilization, thereby significantly improving the quality of sheep milk products.

[0007] Therefore, in the first aspect of the present invention, the present invention provides a method for producing sheep milk. According to an embodiment of the present invention, the method comprises: filtering a sheep milk raw material and collecting a filtrate; subjecting the filtrate to a high-pressure microfluidization homogenization treatment to obtain a pre-sterilization treatment product; and subjecting the pre-sterilization treatment product to a cold plasma treatment to obtain sheep milk.

[0008] According to the method of the embodiment of the present invention, high-pressure microfluidic homogenization is combined with cold plasma sterilization technology to complete the homogenization, pre-sterilization and sterilization of sheep milk at room temperature. This method not only extends the shelf life of sheep milk, but also effectively retains the functional factors in sheep milk, avoids the destruction of these functional factors by high-temperature sterilization, and thus significantly improves the quality of sheep milk products.

[0009] According to an embodiment of the present invention, the method for producing sheep milk may further include at least one of the following additional technical features: According to an embodiment of the present invention, the filtration process is performed by tangential flow filtration.

[0010] According to an embodiment of the present invention, the tangential flow filtration satisfies at least one of the following conditions: the transmembrane pressure of the tangential flow filtration is 0.1-0.25MPa; the inlet pressure of the tangential flow filtration is 0.3-0.5MPa, and the outlet pressure is 0.1-0.2MPa; the permeation pressure of the tangential flow filtration is 0.1-0.2MPa; the pore size of the membrane in the tangential flow filtration is 0.3-0.5μm.

[0011] According to an embodiment of the present invention, the filtration process is performed in a tangential flow filtration device.

[0012] According to an embodiment of the present invention, the high-pressure microfluidic homogenization treatment satisfies at least one of the following conditions: the pressure of the high-pressure microfluidic homogenization treatment is 120-250MPa; the temperature of the high-pressure microfluidic homogenization treatment is 45-55°C; the number of high-pressure microfluidic homogenization treatment is 1-3 times.

[0013] According to an embodiment of the present invention, the cold plasma treatment satisfies at least one of the following conditions: the discharge medium of the cold plasma treatment is oxygen; the frequency of the cold plasma treatment is 5-15kHz; the voltage of the cold plasma treatment is 15-25kV; and the time of the cold plasma treatment is 1-5min.

[0014] According to an embodiment of the present invention, the high-pressure microfluidic homogenization treatment is carried out in a high-pressure microfluidic homogenizer; and the cold plasma treatment is carried out in a low-temperature plasma device.

[0015] According to an embodiment of the present invention, before the sheep milk raw material is filtered, the method further comprises: performing milk purification on the sheep milk raw material.

[0016] According to an embodiment of the present invention, the milk purifying process is performed in a milk purifying machine.

[0017] In the second aspect of the present invention, the present invention provides a kind of sheep milk. According to an embodiment of the present invention, the sheep milk is prepared by the production method described in the first aspect. Therefore, the sheep milk prepared by the production method of the present invention completely retains its rich nutrients, such as protein, fat and calcium, and is highly close to fresh sheep milk in quality, fully meeting consumers' demand for high-quality dairy products. At the same time, the sheep milk also has a long shelf life, further enhancing the market competitiveness and consumer experience of the product.

[0018] Additional aspects and advantages of the present invention will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The above and / or additional aspects and advantages of the present invention will become apparent and easily understood from the description of the embodiments in conjunction with the following drawings, in which: Figure 1 The fresh goat milk production process according to the embodiment of the present invention is Figure 1 ; Figure 2 The fresh goat milk production process according to the embodiment of the present invention is Figure 2 ; Figure 3 The fresh goat milk production process according to the embodiment of the present invention is Figure 3 . DETAILED DESCRIPTION

[0020] The following embodiments of the technical solution of the present invention are described in detail. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and are therefore only used as examples, and cannot be used to limit the protection scope of the present invention.

[0021] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present invention. The appearance of the phrase in various places in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0022] "Scope" disclosed in the present invention is defined in the form of lower limit and upper limit, and a given range is defined by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundary of a special range. The scope defined in this way can be including end values, and can be arbitrarily combined, that is, any lower limit can be combined with any upper limit to form a scope. For example, if the scope of 60-120 and 80-110 is listed for a specific parameter, it is understood that the scope of 60-110 and 80-120 is also expected. In addition, if the minimum range values ​​1 and 2 are listed, and if the maximum range values ​​3,4 and 5 are listed, the following scope can all be expected: 1-3, 1-4, 1-5, 2-3, 2-4 and 2-5. In the present invention, unless otherwise specified, the numerical range "ab" represents the abbreviation of any real number combination between a and b, wherein a and b are real numbers, and the scope defined in this way can be including end values ​​a and b. For example, the numerical range "0-5" means that all real numbers between "0-5" are listed in this document, and "0-5" is just an abbreviation of these numerical combinations. In addition, when a parameter is expressed as an integer ≥ 2, it is equivalent to disclosing that the parameter is, for example, an integer of 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0023] If not otherwise specified, all embodiments and optional embodiments of the present invention can be combined with each other to form a new technical solution.

[0024] Unless otherwise specified, all technical features and optional technical features of the present invention can be combined with each other to form a new technical solution.

[0025] The present invention provides a method for producing sheep milk and sheep milk, which will be described in detail below.

[0026] How sheep milk is produced In a first aspect of the present invention, the present invention provides a method for producing sheep milk. Figure 2 , the method comprising: S100: Filtration In this process, the sheep milk raw material is filtered and the filtrate is collected.

[0027] In some embodiments of the present invention, the filtration treatment is performed by tangential flow filtration. By adopting the tangential flow filtration method, the flow rate and flow rate of the fluid are increased, the filtration time is shortened, the filtration efficiency is improved, and the impurities in the sheep milk can be effectively intercepted, and solvents such as lactose and water can be removed, thereby increasing the content of protein and calcium; in addition, this filtration method reduces the deposition of impurities on the membrane surface, reduces the degree of membrane contamination, and thus reduces the number of cleaning times and cleaning costs.

[0028] In this article, the "tangential flow filtration" can also be called high-flow membrane filtration, which means that the flow direction of the liquid is parallel to the membrane surface. Under the action of pressure, only a part of the liquid passes through the filter membrane and enters the downstream, so that the liquid can circulate with the flow rate and also flush the membrane surface, avoiding the accumulation of large molecules on the membrane surface and preventing concentration polarization from reducing the flow rate, thereby maintaining a stable flow rate, which can effectively filter and extend the life of the filter membrane.

[0029] In some embodiments of the present invention, the inlet pressure (PF) of the tangential flow filtration is 0.3-0.5MPa, and the outlet pressure (PR) is 0.1-0.2MPa. For example, the inlet pressure can be 0.3MPa, 0.32MPa, 0.35MPa, 0.38MPa, 0.4MPa, 0.42MPa, 0.45MPa, 0.48MPa, 0.5MPa, etc., or can be a range composed of any of the above arrays. For example, the outlet pressure can be 0.1MPa, 0.11MPa, 0.12MPa, 0.13MPa, 0.14MPa, 0.15MPa, 0.16MPa, 0.17MPa, 0.18MPa, 0.19MPa, 0.2MPa, etc., or can be a range composed of any of the above arrays. By controlling the inlet pressure and the outlet pressure, the transmembrane pressure can be adjusted. The transmembrane pressure determines the driving force for the liquid to pass through the membrane. Too high a transmembrane pressure may lead to increased membrane pollution, while too low a transmembrane pressure will slow down the filtration speed. Therefore, by making the inlet pressure and outlet pressure of the tangential flow filtration within the above range, the transmembrane pressure of the sheep milk can be controlled within an appropriate range, thereby improving the filtration efficiency of the sheep milk, achieving the best filtration effect, and reducing membrane pollution. In some embodiments of the present invention, the inlet pressure of the tangential flow filtration is 0.4MPa, and the outlet pressure is 0.2MPa.

[0030] In some embodiments of the present invention, the permeation pressure (Pp) of the tangential flow filtration is 0.1-0.2MPa. For example, it can be 0.1MPa, 0.11MPa, 0.12MPa, 0.13MPa, 0.14MPa, 0.15MPa, 0.16MPa, 0.17MPa, 0.18MPa, 0.19MPa, 0.2MPa, etc. The permeation pressure is the main driving force for the liquid to pass through the membrane. By reasonably controlling the permeation pressure, the flow rate of the liquid through the membrane can be adjusted to optimize the filtration efficiency. Therefore, by making the permeation pressure within the above range, the filtration efficiency of sheep milk can be improved, the best filtration effect can be achieved, and membrane pollution can be reduced, and excessive compression and clogging of the membrane can be avoided. In some embodiments of the present invention, the permeation pressure of the tangential flow filtration is 0.1MPa.

[0031] In some embodiments of the present invention, the transmembrane pressure (TMP) of the tangential flow filtration is 0.1-0.25 MPa. For example, it can be 0.1 MPa, 0.12 MPa, 0.15 MPa, 0.18 MPa, 0.2 MPa, 0.22 MPa, 0.25 MPa, etc., or it can be a range composed of any array of the above. Therefore, by making the transmembrane pressure within the above range, the filtration efficiency of sheep milk can be improved, the best filtration effect can be achieved, and membrane pollution can be reduced to avoid excessive compression and clogging of the membrane. In some embodiments of the present invention, the transmembrane pressure (TMP) of the tangential flow filtration is 0.2 MPa.

[0032] It should be noted that the transmembrane pressure refers to the average pressure difference between the upstream and downstream of the filter membrane, that is, TMP=[(PF+PR) / 2]-Pp.

[0033] In some embodiments of the present invention, the pore size of the membrane in the tangential flow filtration is 0.3-0.5 μm. For example, it can be 0.3 μm, 0.32 μm, 0.35 μm, 0.38 μm, 0.4 μm, 0.42 μm, 0.45 μm, 0.48 μm, 0.5 μm, etc., or it can be a range composed of any of the above arrays. Therefore, by making the pore size of the membrane within the above range, not only can the solvent components such as lactose and water in sheep milk be efficiently removed, but also key nutrients such as protein, fat and calcium can be accurately retained, thereby significantly improving the product quality of sheep milk, making its nutritional components richer and more balanced, and better meeting consumers' demand for high-quality dairy products.

[0034] In some embodiments of the present invention, the filtration process is performed in a tangential flow filtration device.

[0035] S200: High-pressure microfluidization homogenization In this treatment process, the filtrate obtained after the filtration treatment is subjected to high-pressure micro-jet homogenization treatment to obtain a pre-sterilization treatment product. Therefore, by adopting high-pressure micro-jet homogenization treatment, on the one hand, the fat globules and other particles in the sheep milk can be homogenized to the micron or even nanometer level, and efficient dispersion and homogenization treatment can be achieved, which helps to improve the stability and taste of the sheep milk, prevent the aggregation and floating of the fat globules, and make the sheep milk more delicate and uniform; on the other hand, the microorganisms in the sheep milk will be affected by the impact and shear force of the high-speed jet, which can directly destroy the cell structure of the microorganisms, making them inactive or dead; in addition, when the sheep milk passes through the homogenization chamber of the high-pressure micro-jet homogenizer, a cavitation effect will be generated, and the formation and collapse of the cavitation will release a large amount of energy, which can have a destructive effect on the microbial cells, thereby playing a pre-sterilization role.

[0036] In some embodiments of the present invention, the pressure of the high-pressure microjet homogenization treatment is 120-250MPa. For example, it can be 120MPa, 150MPa, 180MPa, 200MPa, 220MPa, 250MPa, etc., or it can be a range composed of any of the above arrays. Thus, by making the pressure within the above range, it can achieve better homogenization and pre-sterilization effects, further refine the fat globules in sheep milk, and distribute them more evenly, thereby improving the stability and taste of the product. In some embodiments of the present invention, the pressure of the high-pressure microjet homogenization treatment is 190-210MPa, preferably 200MPa.

[0037] In some embodiments of the present invention, the temperature of the high-pressure microfluidic homogenization treatment is 45-55°C. For example, it can be 45°C, 48°C, 50°C, 52°C, 55°C, etc., or it can be a range composed of any of the above arrays. Therefore, by keeping the temperature within the above range, a better sterilization effect can be achieved, while preventing the temperature-sensitive active ingredients in sheep milk from denaturing or inactivating due to high temperature, thereby ensuring that the nutrients and active substances in sheep milk remain stable. In some embodiments of the present invention, the temperature of the high-pressure microfluidic homogenization treatment is 48-52°C, preferably 50°C.

[0038] In some embodiments of the present invention, the number of high-pressure microfluidization homogenization treatments is 1-3 times. For example, it can be 1 time, 2 times, 3 times, or a range composed of any of the above arrays. In this way, the fat globules and protein particles in the sheep milk can be more refined and distributed more evenly, thereby improving the stability and taste of the product. In some embodiments of the present invention, the number of high-pressure microfluidization homogenization treatments is 2 times.

[0039] In some embodiments of the present invention, the high-pressure microfluidizer homogenization process is performed in a high-pressure microfluidizer.

[0040] During the research, the inventors found that although high-pressure microfluidic homogenization alone can homogenize sheep milk and play a certain role in sterilization, its sterilization effect is limited, resulting in a high total bacterial count and odor in the prepared sheep milk. To solve this problem, the inventors introduced cold plasma treatment after high-pressure microfluidic homogenization.

[0041] S300: Cold plasma treatment In this treatment process, the pre-sterilized product obtained by high-pressure microfluidization homogenization is treated with cold plasma to obtain sheep milk. Therefore, by using cold plasma treatment, the inactivation rate of bacteria can be further improved under non-thermal conditions, effectively avoiding the damage of high-temperature sterilization to functional factors in sheep milk. At the same time, this treatment method can also increase the phosphorylation degree of casein in sheep milk, thereby enhancing its functional properties, including water holding capacity, solubility, foaming ability and stability, and extending the shelf life of sheep milk.

[0042] It should be noted that plasma is the fourth state of matter, composed of ions, electrons and neutral particles, and is electrically neutral as a whole. Cold plasma, also known as non-equilibrium plasma, has a high electron temperature, while the temperature of ions and neutral particles is close to room temperature. This will not cause thermal damage when processing heat-sensitive materials and is widely used. The core function of cold plasma comes from its high-energy electrons and active particles: destroying microbial cell membranes or DNA (for sterilization), or regulating cell behavior (such as promoting wound healing).

[0043] In some embodiments of the present invention, the discharge medium of the cold plasma treatment is oxygen. Therefore, by using oxygen as the discharge medium, not only can the sterilization effect of the cold plasma be enhanced, but oxygen itself is a non-toxic and harmless gas and will not have a negative impact on the quality of sheep milk.

[0044] In some embodiments of the present invention, the frequency of the cold plasma treatment is 5-15kHz. For example, it can be 5kHz, 7kHz, 10kHz, 12kHz, 15kHz, etc., or it can be a range composed of any array of the above. Therefore, by making the frequency within the above range, it is possible to maximize the retention of nutrients in sheep milk while enhancing the sterilization effect.

[0045] In some embodiments of the present invention, the voltage of the cold plasma treatment is 15-25 kV. For example, it can be 15 kV, 17 kV, 20 kV, 22 kV, 25 kV, etc., or it can be a range composed of any array of the above. Therefore, by making the voltage within the above range, a high-efficiency sterilization effect can be achieved at a lower temperature while avoiding the destruction of the nutrients in the sheep milk.

[0046] In some embodiments of the present invention, the cold plasma treatment time is 1-5 minutes, for example, 1 minute, 2 minutes, 3 minutes, 4 minutes, 5 minutes, etc., or any range of the above arrays. Thus, an efficient sterilization effect can be achieved.

[0047] In some embodiments of the present invention, the cold plasma treatment is performed in a low-temperature plasma equipment.

[0048] In some embodiments of the present invention, the sheep milk raw material is filtered before being filtered. Figure 3 , further comprising: S400: Clean milk treatment In this treatment process, the sheep milk raw material is preliminarily subjected to milk purification treatment, through which mechanical impurities, dust, cell fragments, etc. in the sheep milk raw material can be removed.

[0049] In some embodiments of the present invention, the milk purifying process is performed in a milk purifying machine.

[0050] Sheep milk In the second aspect of the present invention, the present invention provides a kind of sheep milk. According to an embodiment of the present invention, the sheep milk is prepared by the production method described in the first aspect. Therefore, the sheep milk prepared by the production method of the present invention completely retains its rich nutrients, such as protein, fat and calcium, and is highly close to fresh sheep milk in quality, fully meeting consumers' demand for high-quality dairy products. At the same time, the sheep milk also has a long shelf life, further enhancing the market competitiveness and consumer experience of the product.

[0051] The embodiments of the present invention are described in detail below. The embodiments described below are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention. If no specific techniques or conditions are specified in the embodiments, the techniques or conditions described in the literature in this area or the product specifications are used. The reagents or instruments used that do not specify the manufacturer are all conventional products that can be obtained commercially.

[0052] Example 1: Low temperature production of sheep milk 1 According to Figure 1 Process flow chart for producing sheep milk The specific steps are as follows: (1) The refrigerated fresh sheep milk raw materials are passed through a milk purifier to remove mechanical impurities, dust, cell fragments, etc. in the raw materials.

[0053] (2) The sheep milk treated in step (1) is placed in a high-flow membrane filtration device for high-flow membrane filtration treatment to remove water solvents, lactose and other substances and increase protein content and calcium content. The parameters of the high-flow membrane filtration device are: membrane diameter: 0.45 μm, inlet pressure (PF): 0.3 MPa, outlet pressure (PR): 0.1 MPa, permeate pressure (Pp): 0.1 MPa.

[0054] (3) The sheep milk treated in step (2) is placed in a high-pressure microfluidizer for dynamic high-pressure microfluidization treatment to reduce the size of fat particles in the sheep milk and pre-sterilize. The parameters of the high-pressure microfluidizer are: treatment pressure: 120 MPa, treatment temperature 45°C, and treatment times 2 times.

[0055] (4) The sheep milk from step (3) was placed in a quartz reactor and pretreated with plasma for 3 s to promote uniform distribution of the sample. Subsequently, the sample was treated with cold plasma for 1 min to obtain cold plasma treated sheep milk. Cold plasma parameters: frequency of 10 kHz, voltage of 20 kV, and treatment time of 1 min.

[0056] (5) Filling and sealing the sheep milk obtained in step (4), wherein the container used is a pre-sterilized packaging bottle, and the container material is a food-grade crystalline polyester (CPET) packaging material.

[0057] (6) The sheep milk product sterilized in step (5) is cleaned and labeled for storage at 4°C.

[0058] Example 2: Low temperature production of sheep milk 2 Sheep milk was prepared according to the method described in Example 1, except that: (1) The parameters of the high-flow membrane filtration equipment in step (2) are: membrane diameter: 0.45 μm, inlet pressure (PF): 0.4 MPa, outlet pressure (PR): 0.2 MPa, permeate pressure (Pp): 0.1 MPa.

[0059] (2) The parameters of the high-pressure microfluidizer in step (3) are: processing pressure: 200 MPa, processing temperature: 50°C, and processing times: 2 times.

[0060] (3) In step (4), the sample was treated with cold plasma for 5 min.

[0061] Example 3: Low temperature production of sheep milk 3 Sheep milk was prepared according to the method described in Example 1, except that: (1) The parameters of the high-flow membrane filtration equipment in step (2) are: membrane diameter: 0.45 μm, inlet pressure (PF): 0.5 MPa, outlet pressure (PR): 0.2 MPa, permeate pressure (Pp): 0.2 MPa.

[0062] (2) The parameters of the high-pressure microfluidizer in step (3) are: processing pressure: 250 MPa, processing temperature: 55°C, and processing times: 2 times.

[0063] (3) In step (4), the sample was treated with cold plasma for 3 min.

[0064] Comparative Example 1: Dynamic high-pressure microfluidization combined with cold plasma sterilization technology to produce sheep milk at low temperature The following steps are followed to produce sheep milk: (1) The refrigerated fresh sheep milk raw materials are passed through a milk purifier to remove mechanical impurities, dust, cell fragments, etc. in the raw materials.

[0065] (2) The sheep milk treated in step (1) is placed in a high-pressure microfluidizer for dynamic high-pressure microfluidization treatment to reduce the size of fat particles in the sheep milk and pre-sterilize. The parameters of the high-pressure microfluidizer are: treatment pressure: 120 MPa, treatment temperature 45 °C, and treatment times 2 times.

[0066] (3) The sheep milk from step (2) was placed in a quartz reactor and pretreated with plasma for 3 s to promote uniform distribution of the sample. Subsequently, the sample was treated with cold plasma for 1 min to obtain cold plasma treated sheep milk. Cold plasma parameters: frequency of 10 kHz, voltage of 20 KV, and treatment time of 1 min.

[0067] (4) Filling and sealing the sheep milk obtained in step (3), wherein the container used is a pre-sterilized packaging bottle, and the container material is a food-grade crystalline polyester (CPET) packaging material.

[0068] (5) The sheep milk product sterilized in step (4) is cleaned and labeled for storage at 4°C.

[0069] Comparative Example 2: High-flow membrane filtration combined with dynamic high-pressure microfluidization homogenization and low-temperature production of sheep milk The following steps are followed to produce sheep milk: (1) The refrigerated fresh sheep milk raw materials are passed through a milk purifier to remove mechanical impurities, dust, cell fragments, etc. in the raw materials.

[0070] (2) The sheep milk treated in step (1) is placed in a high-flow membrane filtration device for high-flow membrane filtration treatment to remove water solvents, lactose and other substances and increase protein content and calcium content. The parameters of the high-flow membrane filtration device are: membrane diameter: 0.45 μm, inlet pressure (PF): 0.5 MPa, outlet pressure (PR): 0.2 MPa, permeate pressure (Pp): 0.2 MPa.

[0071] (3) The sheep milk treated in step (2) is placed in a high-pressure microfluidizer for dynamic high-pressure microfluidization treatment to reduce the size of fat particles in the sheep milk and pre-sterilize. The parameters of the high-pressure microfluidizer are: treatment pressure: 200 MPa, treatment temperature 50°C, and treatment times 2 times.

[0072] (4) Filling and sealing the sheep milk obtained in step (3), wherein the container used is a pre-sterilized packaging bottle, and the container material is a food-grade crystalline polyester (CPET) packaging material.

[0073] (5) The sheep milk product sterilized in step (4) is cleaned and labeled for storage at 4°C.

[0074] Comparative Example 3: High-flow membrane filtration combined with cold plasma sterilization technology to produce sheep milk at low temperature The following steps are followed to produce sheep milk: (1) The refrigerated fresh sheep milk raw materials are passed through a milk purifier to remove mechanical impurities, dust, cell fragments, etc. in the raw materials.

[0075] (2) The sheep milk treated in step (1) is placed in a high-flow membrane filtration device for high-flow membrane filtration treatment to remove water solvents, lactose and other substances and increase protein content and calcium content. The parameters of the high-flow membrane filtration device are: membrane diameter: 0.45 μm, inlet pressure (PF): 0.5 MPa, outlet pressure (PR): 0.2 MPa, permeate pressure (Pp): 0.2 MPa.

[0076] (3) The sheep milk from step (2) was placed in a quartz reactor and pretreated with plasma for 3 s to promote uniform distribution of the sample. Subsequently, the sample was treated with cold plasma for 5 min to obtain cold plasma treated sheep milk. Cold plasma parameters: frequency of 10 kHz, voltage of 20 kV, and treatment time of 5 min.

[0077] (4) Filling and sealing the sheep milk obtained in step (3), wherein the container used is a pre-sterilized packaging bottle, and the container material is a food-grade crystalline polyester (CPET) packaging material.

[0078] (5) The sheep milk product sterilized in step (4) is cleaned and labeled for storage at 4°C.

[0079] Product Testing The sensory and microbial contents of the sheep milk obtained in the above Examples 1-3 and Comparative Examples 1-3 were tested.

[0080] The determination methods of sensory quality, total colony count and Escherichia coli were all determined with reference to the methods cited in GB 19645-2010.

[0081] The experimental results are shown in Table 1 and Table 2. The sheep milk produced by the method of the present invention is superior to Comparative Examples 1-3 in terms of protein content, total bacterial count and storage time, and is normal in terms of color, taste, smell and tissue state, without any abnormalities. This shows that only by combining high-flow membrane filtration, high-pressure microjet homogenization and cold plasma can the prepared sheep milk have excellent quality and extend the shelf life of the sheep milk. Among them, the sheep milk prepared in Example 2 performs best in terms of protein content, fat content and calcium content, and the average fat particle size and total bacterial count are the lowest.

[0082] Table 1: Test results of physical and chemical indicators of sheep milk

[0083] Table 2: Results of sheep milk quality tests

[0084] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0085] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations of the present invention. A person skilled in the art may change, modify, replace and vary the above embodiments within the scope of the present invention.

Claims

1. A method for producing sheep milk, characterized in that: include: Filtering the sheep milk raw material and collecting the filtrate; The filtrate is subjected to high-pressure microfluidization homogenization treatment to obtain a pre-sterilization product; The pre-sterilization product is subjected to cold plasma treatment to obtain sheep milk.

2. The production method according to claim 1, characterized in that The filtration treatment is performed by tangential flow filtration.

3. The production method according to claim 2, characterized in that: The tangential flow filtration satisfies at least one of the following conditions: The transmembrane pressure of the tangential flow filtration is 0.1-0.25 MPa; The inlet pressure of the tangential flow filtration is 0.3-0.5MPa, and the outlet pressure is 0.1-0.2MPa; The permeation pressure of the tangential flow filtration is 0.1-0.2MPa; The pore size of the membrane in the tangential flow filtration is 0.3-0.5 μm.

4. The production method according to claim 3, characterized in that: The filtration process is carried out in a tangential flow filtration device.

5. The production method according to claim 1, characterized in that: The high-pressure microfluidization homogenization process satisfies at least one of the following conditions: The pressure of the high-pressure microfluidization homogenization treatment is 120-250 MPa; The temperature of the high-pressure microfluidization homogenization treatment is 45-55°C; The high-pressure microfluidization homogenization treatment is performed 1 to 3 times.

6. The production method according to claim 5, characterized in that The cold plasma treatment satisfies at least one of the following conditions: The discharge medium of the cold plasma treatment is oxygen; The frequency of the cold plasma treatment is 5-15kHz; The voltage of the cold plasma treatment is 15-25 kV; The cold plasma treatment time is 1-5 minutes.

7. The production method according to claim 6, characterized in that: The high-pressure microfluidizer homogenization process is carried out in a high-pressure microfluidizer; The cold plasma treatment is performed in a low-temperature plasma device.

8. The production method according to claim 1, characterized in that: Before the sheep milk raw material is filtered, the method further comprises: performing milk purification on the sheep milk raw material.

9. The production method according to claim 8, characterized in that: The milk purification process is carried out in a milk purifier.

10. A sheep milk, characterized in that: The invention is prepared by the production method according to any one of claims 1 to 9.

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