An additive-free foaming milk and a method for preparing the same

Abstract

The application provides a kind of no-added foaming milk and its preparation method.The preparation method comprises the following steps: separating raw milk to obtain cream and skim milk;optionally, the cream is cooled and crystallized, stirred, filtered to remove part of milk fat globule membrane, and then treated by deacidification to obtain a feed liquid A;the skim milk is micro-filtered to obtain a feed liquid B and a feed liquid C;for UHT milk, the feed liquid A, the feed liquid B and the feed liquid C are mixed in a certain proportion to obtain a first mixed feed liquid;for pasteurized milk, the cream, the feed liquid B and the feed liquid C are mixed in a certain proportion to obtain a second mixed feed liquid;after homogenization and sterilization of the first mixed feed liquid or the second mixed feed liquid, no-added foaming milk is obtained.The foaming milk of the application has excellent foaming performance without adding other ingredients;after steam whipping, the liquid part is perfectly combined with coffee, the bitterness is modified, the smoothness is improved, the milk foam part is soft and delicate, and is stable and easy to whip.

Description

Technical Field

[0001] This invention relates to an additive-free foamed milk and its preparation method, belonging to the field of liquid dairy product technology. Background Technology

[0002] In recent years, the coffee industry has seen a proliferation of products, with coffee and milk combinations creating various product categories. Different ratios of espresso extract to hot milk result in different products, such as latte, macchiato, cappuccino, and flat white. Currently, most coffee shops, street vendors, and convenience stores use steam espresso machines to heat and froth milk to 60-70°C before blending it with coffee extract for latte art. Many factors influence the taste of coffee with milk, primarily the type of coffee beans, the degree of roasting, and the quality of the milk.

[0003] Currently, there are two main types of milk used to make coffee milk products: one is white milk, which is required by national regulations to have no other ingredients added and can be sterilized using pasteurization or ultra-high temperature sterilization. This type of product is healthy and nutritious, but the milk foam is not dense enough and is unstable; the other type is flavored milk, which usually has milk fat, emulsifiers, and thickeners added to improve its foaming ability. However, due to the addition of additives, it cannot meet the health needs of some consumers.

[0004] Current research on foamed milk primarily focuses on external additives to enhance its foaming properties. These include additives such as microcrystalline cellulose, gellan gum, α-cyclodextrin, soluble soybean polysaccharides, and sodium alginate, which stabilize the foam. However, this approach can lead to excessively high product costs and unnatural flavors. Furthermore, the addition of additives may alienate some consumers, hindering the presentation of a nutritious and healthy product. Alternatively, fortification with milk fat by adding additional milk fat, or the use of compounded and externally added sodium caseinate and whey protein powder, can also improve the foaming performance of milk. However, there is currently no research on improving milk foaming properties solely by adjusting the internal components of the milk without adding any external substances.

[0005] Therefore, developing an additive-free foaming milk and its preparation method has become one of the urgent problems to be solved in this field. Summary of the Invention

[0006] To address the aforementioned technical problems, the present invention aims to provide an additive-free foaming milk and its preparation method. The foaming milk of the present invention exhibits excellent foaming performance without the addition of any other ingredients.

[0007] To achieve the above objectives, the first aspect of the present invention provides a method for preparing additive-free foaming milk;

[0008] When the additive-free foamed milk is ultra-high temperature sterilized milk, the preparation method of the additive-free foamed milk includes the following steps:

[0009] 1-(1) Separate the raw milk to obtain light cream and skim milk;

[0010] 1-(2) After cooling and crystallizing the cream, stirring and filtering, a portion of the milk fat globule membrane is removed from the cream.

[0011] 1-(3) The light cream with part of the milk fat globule membrane removed is subjected to deacidification treatment to obtain liquid A;

[0012] 1-(4) The skim milk is microfiltered to obtain liquid B (whey protein) and liquid C (casein);

[0013] 1-(5) Mix the liquid A, the liquid B and the liquid C in a certain proportion to obtain the first mixed liquid;

[0014] 1-(6) After homogenizing and ultra-high temperature sterilization (UHT) of the first mixture liquid, the additive-free foamed milk is obtained;

[0015] When the additive-free foamed milk is pasteurized milk, the preparation method of the additive-free foamed milk includes the following steps:

[0016] 2-(1) Separate the raw milk to obtain light cream and skim milk;

[0017] 2-(2) The skim milk is separated by microfiltration to obtain liquid B (whey protein) and liquid C (casein);

[0018] 2-(3) Mix the light cream, liquid B and liquid C in a certain proportion to obtain a second mixed liquid;

[0019] 2-(4) After homogenizing and pasteurizing the second mixture, the additive-free foamed milk is obtained.

[0020] In the above preparation method, preferably, in steps 1-(1) and 2-(1), the raw milk includes, but is not limited to, one or a combination of several of cow's milk, goat's milk and camel's milk.

[0021] In the above preparation method, preferably, in steps 1-(1) and 2-(1), the raw milk is raw milk that has undergone acceptance, purification, and degassing. The acceptance is carried out according to GB 19301. More preferably, the purification is performed at 2-60℃ with a centrifugal force of 4000-5000g. More preferably, the degassing is performed at -0.04 to -0.08 bar for 0.1-0.2s.

[0022] In the above preparation method, preferably, in steps 1-(1) and 2-(1), the separation is performed by centrifugation at 50-60°C. More preferably, the centrifugal force for centrifugation is 6000-7000g.

[0023] In the above preparation method, preferably, in steps 1-(1) and 2-(1), the fat content of the cream is 30-35% based on the total mass of 100%; and the fat content of the skim milk is ≤0.06% based on the total mass of 100%.

[0024] In the above preparation method, preferably, in step 1-(2), the cooling crystallization temperature is 2-4℃ and the time is 10-20h.

[0025] In the above preparation method, preferably, in steps 1-(2), the stirring speed is 500-1000 rpm and the time is 20-30 min. The stirring can be carried out at room temperature.

[0026] In the above preparation method, preferably, in step 1-(2), the filtration is performed using a filter with a pore size of 0.7-0.9 μm. The filtration can be carried out at room temperature. Currently, the milk fat globule membrane removal technology is used for the extraction of milk fat globule membranes from milk, while the present invention utilizes this technology to reduce the content of polar lipids in milk. Since the milk fat globule membrane can encapsulate fat globules and prevent fat aggregation, if the milk fat globule membrane content is too low, the fat in the milk will aggregate and cannot be evenly dispersed in the milk. Therefore, unlike conventional milk fat globule membrane extraction technology, which requires removing as much milk fat globule membrane as possible, the inventors of the present invention, after extensive research, selected a filter with a pore size of 0.7-0.9 μm for filtration to remove part of the milk fat globule membrane. This treatment can retain a certain amount of milk fat globule membrane to ensure that it can still encapsulate fat globules, avoid fat aggregation, ensure the uniform distribution of fat, and thus ensure the stability of milk products. This invention does not limit the amount of milk fat globule membrane removed, but by using the filtration technique with a pore size of 0.7 to 0.9 μm as specified in this invention, the amount of milk fat globule membrane removed and retained can reach the optimal balance, thereby reducing the polar lipid content in milk while ensuring the stability of the milk product.

[0027] In the above preparation method, preferably, in step 1-(3), the deacidification treatment of the cream after removing part of the milk fat globule membrane is carried out using an adsorption column filled with alkaline microcrystalline cellulose. This invention uses adsorption chromatography technology for deacidification treatment. The deacidification treatment can be carried out at room temperature. Deacidification treatment technology is often used to remove free fatty acids from vegetable oils, but its application in liquid dairy products has not yet been found. Most of the free fatty acids in raw milk are encapsulated in fat globules. This invention innovatively removes part of the milk fat globule membrane and then deacidifies the released free fatty acids, which can effectively reduce the content of polar lipids in milk, while the change in fat content is minimal and will not affect the nutrition, flavor, taste, or texture of the product.

[0028] In the above preparation method, preferably, in steps 1-(4) and 2-(2), the microfiltration separation uses a microfiltration membrane with a pore size of 20-100 nm (more preferably a microfiltration membrane with a pore size of 90-100 nm), the operating pressure is 1-3 bar, and the temperature is 5-60℃ (more preferably 50-60℃). The retentate after microfiltration membrane separation is a casein solution (i.e., feed solution C), and the permeate is a whey protein solution (i.e., feed solution B).

[0029] In the above preparation method, preferably, in steps 1-(5), based on the total mass of the first mixed liquid as 100%, the fat content is 3-5%, the protein content is 3-4.5%, and the mass ratio of whey protein to casein is 1:2-2:1 (more preferably 1:1-2:1). The mixing ratio of the liquid A, the liquid B, and the liquid C can be determined by the fat content, protein content, and mass ratio of whey protein to casein in the first mixed liquid as defined in this invention. Therefore, this invention does not further limit the mixing ratio of the liquid A, the liquid B, and the liquid C.

[0030] In the above preparation method, preferably, in steps 2-(3), based on the total mass of the second mixture as 100%, the fat content is 3-5%, the protein content is 3-4.5%, and the mass ratio of whey protein to casein is 1:4-1:10 (more preferably 1:5-1:10). The mixing ratio of the cream, the liquid B, and the liquid C can be determined by the fat content, protein content, and mass ratio of whey protein to casein in the second mixture as defined in this invention. Therefore, this invention does not further limit the mixing ratio of the cream, the liquid B, and the liquid C.

[0031] This invention innovatively employs microfiltration separation technology to separate and reorganize proteins in skim milk through membrane separation, adjusting the content and ratio of whey protein and casein, which can effectively adjust the influence of milk proteins on the foaming properties of milk.

[0032] In the above preparation method, preferably, in steps 1-(6) and 2-(4), the homogenization temperature is 50-60℃ and the pressure is 170-210 bar.

[0033] In the above preparation method, preferably, in step 1-(6), the ultra-high temperature sterilization temperature is 132-160℃ and the time is 0.05-15s.

[0034] In the above preparation method, preferably, in step 2-(4), the pasteurization temperature is 72-95℃ and the time is 15-300s.

[0035] In the above preparation method, preferably, after ultra-high temperature sterilization and pasteurization in steps 1-(6) and 2-(4), respectively, a cooling and filling step is also included to obtain the additive-free foamed milk. The cooling can be to below 4°C. The filling can be performed according to conventional techniques in the art.

[0036] Foam is a two-phase system consisting of a gas and a liquid phase. A surfactant encapsulates the gas, forming a discontinuous phase dispersed in the liquid phase, which is the continuous phase. Milk contains two types of surfactants: high-molecular-weight surfactants (mainly proteins) and low-molecular-weight surfactants (mainly polar lipids in milk fat, including monoglycerides, diglycerides, free fatty acids, and phospholipids). Both types of surfactants promote foam formation and stability. Proteins stabilize foam by forming a viscoelastic film on their surface, while polar lipids stabilize foam through the Gibbs-Marangoni mechanism. Because the stabilization mechanisms of proteins and fats are incompatible, in milk with low fat content, polar lipids can adsorb into the protein adsorption layer, filling the gaps in the protein membrane and improving stability. However, as the fat content increases, polar lipids and proteins compete on the liquid film, reducing stability. Therefore, although proteins and polar lipids can each stabilize foam and emulsion individually, their respective stabilization mechanisms are incompatible. When both substances are present in large quantities at the interface, they conflict, often leading to severe instability and affecting the foaming properties of milk.

[0037] The polar lipids in milk mainly include monoglycerides and diglycerides, free fatty acids, phospholipids, etc. Phospholipids are mainly found in the milk fat globule membrane and are the most important polar lipids, while monoglycerides, diglycerides, and free fatty acids are products of fat decomposition and oxidation, and are usually present in low amounts.

[0038] This invention effectively reduces the content of polar lipids in milk by removing part of the milk fat globule membrane through filtration and deacidifying to remove free fatty acids, while the change in fat content is minimal, without affecting the product's nutrition, flavor, texture, or stability. Because the milk fat globule membrane encapsulates fat globules and prevents fat aggregation, excessive removal of the membrane can lead to incomplete encapsulation of fat globules, causing them to aggregate and float, affecting product stability. Furthermore, the free fatty acids originally present in the fat globules are released, which can reduce foaming performance. Therefore, through extensive research, the inventors of this invention selected the most suitable filtration technology to control the amount of milk fat globule membrane removed, achieving the perfect degree of removal. Furthermore, they innovatively deacidify the released free fatty acids after removing part of the milk fat globule membrane, effectively reducing the content of polar lipids in milk and improving foaming performance.

[0039] Regarding proteins, their excellent foaming and emulsifying properties stem from their numerous amphipathic groups, allowing them to rapidly migrate to the surfaces of both the aqueous and gas phases. Hydrophilic groups bind to the aqueous phase, while hydrophobic groups bind to the gas phase, reducing surface tension and forming a viscoelastic film that promotes bubble formation and stability. However, proteins often fold or helix to form spatial structures, further binding together to form stable protein complexes. Hydrophobic groups are often folded inside the protein, affecting its foaming and emulsifying properties. Therefore, appropriately denaturing proteins to open their secondary, tertiary, and quaternary structures exposes the hydrophobic groups, improving foaming performance. Between whey and casein, whey protein is more prone to heat denaturation than casein. Ultra-high temperature sterilization typically induces significant denaturation in whey protein, while casein requires much higher temperatures for denaturation.

[0040] The sterilization processes of 132-160℃ for 0.05-15s and 72-95℃ for 15-300s described in this invention correspond to two types of products: ultra-high temperature sterilized milk (pure milk) and pasteurized milk (fresh milk). Because whey protein undergoes varying degrees of denaturation under these specific sterilization processes, it affects foaming properties. Therefore, this invention innovatively develops the content and ratio of whey protein and casein for different specific sterilization conditions, effectively adjusting the influence of milk proteins on milk foaming properties.

[0041] Based on the above points and the significant contribution of milk fat to milk flavor, this invention targets different sterilization processes by selectively removing polar lipids and altering the composition of milk proteins. This allows polar lipids or milk proteins to act as the main surfactants in milk, effectively avoiding the interaction between the two components, improving the milk's foaming ability, and minimizing changes in milk fat content, thus having virtually no impact on the flavor of the milk product. Furthermore, increasing the milk fat content can further enhance the flavor. Specifically, for UHT milk, some polar lipids (phospholipids, free fatty acids, etc.) are removed through filtration to remove part of the milk fat globule membrane and deacidification. Simultaneously, microfiltration membrane separation and recombination technology is used to increase the whey protein / casein ratio, making milk protein the main surfactant to promote foaming. The product has a fat content of 3-5%, a protein content of 3-4.5%, and a whey protein to casein mass ratio of 1:2-2:1 (more preferably 1:1-2:1). For pasteurized milk, microfiltration membrane separation and recombination technology is used to reduce whey protein content... The protein / casein ratio allows milk fat to act as the main surfactant to promote foaming. The product contains 3-5% fat and 3-4.5% protein, with a whey protein to casein mass ratio of 1:4-1:10 (more preferably 1:5-1:10). Ultimately, the prepared milk product has excellent foaming performance without the addition of other ingredients (such as some foaming and foam-stabilizing additives), and ensures that the product has excellent nutrition, flavor, mouthfeel, texture, and stability, while also significantly improving the product's taste and flavor richness.

[0042] A second aspect of the present invention provides an additive-free foaming milk, which is prepared by the above-described preparation method.

[0043] According to a specific embodiment of the present invention, preferably, the additive-free foaming milk is ultra-high temperature (UHT) sterilized milk, and based on 100% of the total mass of the UHT milk, the fat content is 3-5%, the protein content is 3-4.5%, and the mass ratio of whey protein to casein is 1:2-2:1 (more preferably 1:1-2:1); or, the additive-free foaming milk is pasteurized milk, and based on 100% of the total mass of the pasteurized milk, the fat content is 3-5%, the protein content is 3-4.5%, and the mass ratio of whey protein to casein is 1:4-1:10 (more preferably 1:5-1:10).

[0044] This invention addresses the conflict between the foaming properties and mechanisms of two types of surfactants in milk—proteins and milk fats—and the varying degrees of protein denaturation under different sterilization processes. It innovatively employs filtration to remove part of the milk fat globule membrane, deacidification, and microfiltration separation technologies to selectively remove some polar lipids from the milk. Furthermore, by adjusting the ratio of whey protein to casein, it selectively inhibits the foaming effect of a certain type of surfactant, thereby effectively improving the foaming performance of the milk and resulting in a product with excellent foaming ability and foam stability. Therefore, the foamed milk product of this invention, without the addition of other ingredients, possesses excellent foaming performance, product stability similar to or comparable to conventional white milk products, and significantly enhanced taste and flavor richness. After steaming, the liquid portion blends perfectly with coffee, mitigating the bitterness of concentrated coffee extract and improving smoothness, while the foam portion is dense, delicate, stable, and easy to whip. The foamed milk product of this invention not only meets the needs of health and nutrition but also provides a delicious, smooth, and full-bodied experience. Attached Figure Description

[0045] Figure 1 This is a flowchart illustrating a method for preparing additive-free foamed milk according to a specific embodiment of the present invention. Detailed Implementation

[0046] In order to provide a clearer understanding of the technical features, objectives and beneficial effects of the present invention, the technical solution of the present invention will now be described in detail below, but it should not be construed as limiting the scope of implementation of the present invention.

[0047] like Figure 1 As shown, according to a specific embodiment of the present invention, preferably, when the additive-free foaming milk of the present invention is ultra-high temperature sterilized milk, its preparation method includes the following steps:

[0048] (1) The raw milk after acceptance shall be purified (purified at 4000-5000g centrifugal force at 2-60℃) and degassed (degassed for 0.1-0.2s at -0.04 to -0.08 bar); the raw milk includes but is not limited to cow milk, goat milk or camel milk, etc.

[0049] (2) The raw milk that has been inspected, purified, and degassed is centrifuged at 50-60°C with a centrifugal force of 6000-7000g to obtain light cream and skim milk; the fat content of the light cream is 30-35% based on 100% of its total mass; the fat content of the skim milk is ≤0.06% based on 100% of its total mass.

[0050] (3) Cool the cream at 2-4℃ for 10-20h, then stir at 500-1000rpm for 20-30min, and then filter it with a filter screen with a pore size of 0.7-0.9μm to obtain cream with some milk fat globule membrane removed.

[0051] (4) The cream with part of the milk fat globule membrane removed was deacidified by an adsorption column filled with alkaline microcrystalline cellulose to obtain liquid A;

[0052] (5) The skim milk is subjected to microfiltration separation, wherein the microfiltration separation uses a microfiltration membrane with a pore size of 20-100nm (more preferably a microfiltration membrane with a pore size of 90-100nm), the operating pressure is 1-3 bar, and the temperature is 5-60℃ (more preferably 50-60℃) to obtain feed solution B (whey protein) and feed solution C (casein);

[0053] (6) Mix the liquid A, the liquid B and the liquid C in a certain proportion to obtain a first mixed liquid. The total mass of the first mixed liquid is 100%, and the fat content is 3-5%, the protein content is 3-4.5%, and the mass ratio of whey protein to casein is 1:2-2:1 (more preferably 1:1-2:1).

[0054] (7) Homogenize the first mixture at 50-60°C and 170-210 bar;

[0055] (8) Sterilize the homogenized liquid at ultra-high temperature (132-160℃, 0.05-15s);

[0056] (9) After the sterilized liquid is cooled to 4°C, it is bottled to obtain the additive-free foamed milk, which is ultra-high temperature sterilized milk.

[0057] When the additive-free foamed milk of the present invention is pasteurized milk, its preparation method includes the following steps:

[0058] (1) The raw milk after acceptance shall be purified (purified at 4000-5000g centrifugal force at 2-60℃) and degassed (degassed for 0.1-0.2s at -0.04 to -0.08 bar); the raw milk includes but is not limited to cow milk, goat milk or camel milk, etc.

[0059] (2) The raw milk that has been inspected, purified, and degassed is centrifuged at 50-60°C with a centrifugal force of 6000-7000g to obtain light cream and skim milk; the fat content of the light cream is 30-35% based on 100% of its total mass; the fat content of the skim milk is ≤0.06% based on 100% of its total mass.

[0060] (3) The skim milk is subjected to microfiltration separation. The microfiltration separation uses a microfiltration membrane with a pore size of 20-100 nm (more preferably a microfiltration membrane with a pore size of 90-100 nm), the operating pressure is 1-3 bar, and the temperature is 5-60℃ (more preferably 50-60℃) to obtain feed solution B (whey protein) and feed solution C (casein).

[0061] (4) The light cream, liquid B and liquid C are mixed in a certain proportion to obtain a second mixed liquid. The total mass of the second mixed liquid is 100%, the fat content is 3-5%, the protein content is 3-4.5%, and the mass ratio of whey protein to casein is 1:4-1:10 (more preferably 1:5-1:10).

[0062] (5) Homogenize the second mixture at 50-60°C and 170-210 bar;

[0063] (6) Pasteurize the homogenized liquid (72-95℃, 15-300s);

[0064] (7) After the sterilized liquid is cooled to 4°C, it is bottled to obtain the additive-free foamed milk, which is pasteurized milk.

[0065] Example 1

[0066] This embodiment provides an additive-free foamed milk, which is prepared through the following steps:

[0067] (1) The raw milk after acceptance is subjected to purification (purification at 10℃ with a centrifugal force of 4500g) and degassing (degassing at -0.05bar for 0.1s); the raw milk is cow's milk;

[0068] (2) The raw milk that has been inspected, purified, and degassed is centrifuged at 55°C with a centrifugal force of 6000g to obtain light cream and skim milk; the fat content of the light cream is 31.2% based on 100% of its total mass; the fat content of the skim milk is ≤0.06% based on 100% of its total mass.

[0069] (3) The cream was cooled and crystallized at 2°C for 15 hours, then stirred at 800 rpm for 30 minutes, and then filtered through a 0.7 μm pore size filter to obtain cream with some of the milk fat globule membrane removed.

[0070] (4) The cream with part of the milk fat globule membrane removed was deacidified by an adsorption column filled with alkaline microcrystalline cellulose to obtain liquid A;

[0071] (5) The skim milk is subjected to microfiltration separation. The microfiltration separation uses a microfiltration membrane with a pore size of 90 nm, the operating pressure is 3 bar, and the temperature is 55 °C to obtain feed solution B (whey protein) and feed solution C (casein).

[0072] (6) Mix the liquid A, the liquid B and the liquid C in a certain proportion to obtain a first mixed liquid. The total mass of the first mixed liquid is 100%, and the fat content is 3.8%, the protein content is 3.2%, and the mass ratio of whey protein to casein is 1:1.

[0073] (7) Homogenize the first mixture at 55°C and 180 bar;

[0074] (8) The homogenized liquid was sterilized at ultra-high temperature (134℃, 4s);

[0075] (9) After the sterilized liquid is cooled to 4°C, it is bottled to obtain the additive-free foamed milk, which is ultra-high temperature sterilized milk. Based on the total mass of the foamed milk as 100%, the fat content is 3.8%, the protein content is 3.2%, and the mass ratio of whey protein to casein is 1:1.

[0076] Example 2

[0077] This embodiment provides an additive-free foamed milk, which is prepared through the following steps:

[0078] (1) The raw milk after acceptance is subjected to purification (purification at 10℃ with a centrifugal force of 4500g) and degassing (degassing at -0.05bar for 0.1s); the raw milk is cow's milk;

[0079] (2) The raw milk that has been inspected, purified, and degassed is centrifuged at 55°C with a centrifugal force of 6000g to obtain light cream and skim milk; the fat content of the light cream is 30.9% based on 100% of its total mass; the fat content of the skim milk is ≤0.06% based on 100% of its total mass.

[0080] (3) The cream was cooled and crystallized at 2°C for 15 hours, then stirred at 700 rpm for 30 minutes, and then filtered through a 0.7 μm pore size filter to obtain cream with some milk fat globule membrane removed.

[0081] (4) The cream with part of the milk fat globule membrane removed was deacidified by an adsorption column filled with alkaline microcrystalline cellulose to obtain liquid A;

[0082] (5) The skim milk is subjected to microfiltration separation. The microfiltration separation uses a microfiltration membrane with a pore size of 90 nm, the operating pressure is 3 bar, and the temperature is 55 °C to obtain feed solution B (whey protein) and feed solution C (casein).

[0083] (6) Mix the liquid A, the liquid B and the liquid C in a certain proportion to obtain a first mixed liquid. The total mass of the first mixed liquid is 100%, and the fat content is 3.8%, the protein content is 3.2%, and the mass ratio of whey protein to casein is 2:1.

[0084] (7) Homogenize the first mixture at 55°C and 180 bar;

[0085] (8) The homogenized liquid was subjected to ultra-high temperature sterilization (143℃, 0.1s);

[0086] (9) After the sterilized liquid is cooled to 4°C, it is bottled to obtain the additive-free foamed milk, which is ultra-high temperature sterilized milk. Based on the total mass of the foamed milk as 100%, the fat content is 3.8%, the protein content is 3.2%, and the mass ratio of whey protein to casein is 2:1.

[0087] Example 3

[0088] This embodiment provides an additive-free foamed milk, which is prepared through the following steps:

[0089] (1) The raw milk after acceptance is subjected to purification (purification at 10℃ with a centrifugal force of 4500g) and degassing (degassing at -0.05bar for 0.1s); the raw milk is cow's milk;

[0090] (2) The raw milk that has been inspected, purified, and degassed is centrifuged at 55°C with a centrifugal force of 6000g to obtain light cream and skim milk; the fat content of the light cream is 31.8% based on 100% of its total mass; the fat content of the skim milk is ≤0.06% based on 100% of its total mass.

[0091] (3) The cream was cooled and crystallized at 2°C for 15 hours, then stirred at 800 rpm for 30 minutes, and then filtered through a 0.7 μm pore size filter to obtain cream with some of the milk fat globule membrane removed.

[0092] (4) The cream with part of the milk fat globule membrane removed was deacidified by an adsorption column filled with alkaline microcrystalline cellulose to obtain liquid A;

[0093] (5) The skim milk is subjected to microfiltration separation. The microfiltration separation uses a microfiltration membrane with a pore size of 90 nm, the operating pressure is 3 bar, and the temperature is 55 °C to obtain feed solution B (whey protein) and feed solution C (casein).

[0094] (6) Mix the liquid A, the liquid B and the liquid C in a certain proportion to obtain a first mixed liquid. The total mass of the first mixed liquid is 100%, the fat content is 3.8% and the protein content is 4%, and the mass ratio of whey protein to casein is 2:1.

[0095] (7) Homogenize the first mixture at 55°C and 180 bar;

[0096] (8) The homogenized liquid was sterilized at ultra-high temperature (134℃, 4s);

[0097] (9) After the sterilized liquid is cooled to 4°C, it is bottled to obtain the additive-free foamed milk, which is ultra-high temperature sterilized milk. Based on the total mass of the foamed milk as 100%, the fat content is 3.8%, the protein content is 4%, and the mass ratio of whey protein to casein is 2:1.

[0098] Example 4

[0099] This embodiment provides an additive-free foamed milk, which is prepared through the following steps:

[0100] (1) The raw milk after acceptance is subjected to purification (purification at 10℃ with a centrifugal force of 4500g) and degassing (degassing at -0.05bar for 0.1s); the raw milk is cow's milk;

[0101] (2) The raw milk that has been inspected, purified, and degassed is centrifuged at 55°C with a centrifugal force of 6000g to obtain light cream and skim milk; the fat content of the light cream is 31.4% based on 100% of its total mass; the fat content of the skim milk is ≤0.06% based on 100% of its total mass.

[0102] (3) The skim milk is subjected to microfiltration separation. The microfiltration separation uses a microfiltration membrane with a pore size of 100 nm, the operating pressure is 3 bar, and the temperature is 55 °C to obtain feed solution B (whey protein) and feed solution C (casein).

[0103] (4) The light cream, liquid B and liquid C are mixed in a certain proportion to obtain a second mixed liquid. The total mass of the second mixed liquid is 100%, the fat content is 3.8% and the protein content is 3.2%, and the mass ratio of whey protein to casein is 1:7.

[0104] (5) Homogenize the second mixture at 55°C and 180 bar;

[0105] (6) Pasteurize the homogenized liquid (72℃, 15s);

[0106] (7) After the sterilized liquid is cooled to 4°C, it is bottled to obtain the additive-free foamed milk, which is pasteurized milk. Based on the total mass of the foamed milk as 100%, the fat content is 3.8%, the protein content is 3.2%, and the mass ratio of whey protein to casein is 1:7.

[0107] Example 5

[0108] This embodiment provides an additive-free foamed milk, which is prepared through the following steps:

[0109] (1) The raw milk after acceptance is subjected to purification (purification at 10℃ with a centrifugal force of 4500g) and degassing (degassing at -0.05bar for 0.1s); the raw milk is cow's milk;

[0110] (2) The raw milk that has been inspected, purified, and degassed is centrifuged at 55°C with a centrifugal force of 6000g to obtain light cream and skim milk; the fat content of the light cream is 30.7% based on 100% of its total mass; the fat content of the skim milk is ≤0.06% based on 100% of its total mass.

[0111] (3) The skim milk is subjected to microfiltration separation. The microfiltration separation uses a microfiltration membrane with a pore size of 100 nm, the operating pressure is 3 bar, and the temperature is 55 °C to obtain feed solution B (whey protein) and feed solution C (casein).

[0112] (4) The light cream, liquid B and liquid C are mixed in a certain proportion to obtain a second mixed liquid. The total mass of the second mixed liquid is 100%, the fat content is 3.8% and the protein content is 3.2%, and the mass ratio of whey protein to casein is 1:10.

[0113] (5) Homogenize the second mixture at 55°C and 180 bar;

[0114] (6) Pasteurize the homogenized liquid (72℃, 15s);

[0115] (7) After the sterilized liquid is cooled to 4°C, it is bottled to obtain the additive-free foamed milk, which is pasteurized milk. Based on the total mass of the foamed milk as 100%, the fat content is 3.8%, the protein content is 3.2%, and the mass ratio of whey protein to casein is 1:10.

[0116] Example 6

[0117] This embodiment provides an additive-free foamed milk, which is prepared through the following steps:

[0118] (1) The raw milk after acceptance is subjected to purification (purification at 10℃ with a centrifugal force of 4500g) and degassing (degassing at -0.05bar for 0.1s); the raw milk is cow's milk;

[0119] (2) The raw milk that has been inspected, purified, and degassed is centrifuged at 55°C with a centrifugal force of 6000g to obtain light cream and skim milk; the fat content of the light cream is 32.2% based on 100% of its total mass; the fat content of the skim milk is ≤0.06% based on 100% of its total mass.

[0120] (3) The skim milk is subjected to microfiltration separation. The microfiltration separation uses a microfiltration membrane with a pore size of 100 nm, the operating pressure is 3 bar, and the temperature is 55 °C to obtain feed solution B (whey protein) and feed solution C (casein).

[0121] (4) The light cream, liquid B and liquid C are mixed in a certain proportion to obtain a second mixed liquid. The total mass of the second mixed liquid is 100%, the fat content is 4.5% and the protein content is 3.2%, and the mass ratio of whey protein to casein is 1:10.

[0122] (5) Homogenize the second mixture at 55°C and 180 bar;

[0123] (6) Pasteurize the homogenized liquid (72℃, 15℃);

[0124] (7) After the sterilized liquid is cooled to 4°C, it is bottled to obtain the additive-free foamed milk, which is pasteurized milk. Based on the total mass of the foamed milk as 100%, the fat content is 4.5%, the protein content is 3.2%, and the mass ratio of whey protein to casein is 1:10.

[0125] Comparative Example 1

[0126] This comparative study used commercially available Yili pure milk (3.8% fat, 3.2% protein).

[0127] Comparative Example 2

[0128] This comparative example provides an additive-free foamed milk, whose preparation steps are basically the same as those in Example 1, except that steps (3) and (4) are not performed. Step (6) is to mix the light cream, liquid B and liquid C in a certain proportion to obtain a first mixed liquid, so that the fat content, protein content and whey protein to casein mass ratio in the first mixed liquid are still the same as those in Example 1.

[0129] Comparative Example 3

[0130] This comparative example provides an additive-free foamed milk, the preparation steps of which are basically the same as those in Example 2, except that the mass ratio of whey protein to casein in the first mixture is adjusted to 1:5, and the fat content and protein content in the first mixture are still the same as in Example 2.

[0131] Comparative Example 4

[0132] This comparative example provides an additive-free foamed milk, whose preparation steps are basically the same as those in Example 2, except that the ultra-high temperature sterilization (143°C, 0.1s) in step (8) is changed to pasteurization (72°C, 15s).

[0133] Comparative Example 5

[0134] This comparative example provides an additive-free foamed milk, the preparation steps of which are basically the same as those in Example 3, except that: in step (3), a filter with a pore size of 0.4 μm is used for filtration, and step (4) is not performed; in step (6), the liquid obtained in step (3), liquid B and liquid C are mixed to obtain a first mixed liquid, and the fat content, protein content and whey protein to casein mass ratio in the first mixed liquid are still the same as those in Example 3.

[0135] Comparative Example 6

[0136] This comparative example provides an additive-free foamed milk, the preparation steps of which are basically the same as those in Example 4, except that the mass ratio of whey protein to casein in the second mixture is adjusted to 1:2, and the fat content and protein content in the second mixture are still the same as those in Example 4.

[0137] Comparative Example 7

[0138] This comparative example provides an additive-free foamed milk, the preparation steps of which are basically the same as those in Example 4, except that the mass ratio of whey protein to casein in the second mixture is adjusted to 1:12, and the fat content and protein content in the second mixture are still the same as those in Example 4.

[0139] Product Experiment

[0140] I. Product Stability Evaluation

[0141] The stability of the product was tested using a Lumisizer stability analyzer (2000 rpm / min, 25℃) for 4 hours, and the instability coefficient was used as the evaluation index.

[0142] II. Evaluation of Milk Foaming Performance

[0143] Coffee machine steam injection frothing method: Pour 250mL of milk (4-6℃) into a 600mL stainless steel cup. Using a coffee machine (Barcafe, Italy), inject hot steam into the milk. The steam wand is tilted at approximately 70 degrees to the surface of the dispersed liquid, with the steam wand probe positioned 1-2cm to the left of the center of the liquid surface. Initially, the steam wand probe should be inserted about halfway into the liquid surface. Turn on the steam valve. When the temperature reaches 60±5℃ (steam injection time approximately 24±2s), close and tighten the valve. Immediately record the dispersed liquid volume A0 at this point. After standing for 30 minutes, record the dispersed liquid volume A in the beaker. 30 .

[0144]

[0145]

[0146] III. The effect of frothing milk on coffee product performance

[0147] The coffee concentrate was extracted using the coffee machine described above. The frothed milk was then slowly poured into a latte art pitcher. A tasting panel of 30 people rated the density of the milk foam, the blending of the milk and coffee, and overall liking on a scale of 1 to 10 (with Comparative Sample 1 as the control, and a default score of 6).

[0148] Milk foam density: the uniformity of milk foam size and the smoothness of the texture when tasted.

[0149] The blending properties of milk and coffee: the degree to which milk and coffee blend, and whether the flavor is rich and harmonious.

[0150] The product test results are shown in Tables 1 and 2 below.

[0151] Table 1: Evaluation of Product Stability and Foaming Performance

[0152]

[0153]

[0154] The instability coefficient is essentially an evaluation of the uniformity of the product during centrifugation. The larger the coefficient, the less stable the product. As can be seen from Table 1, under the condition that the protein and fat indicators are basically the same, except for Comparative Example 5, the stability is close to that of the pure milk in Comparative Example 1. However, the instability coefficient of Comparative Example 5 is significantly higher than that of other products. This is because Comparative Example 5 has removed a large amount of milk fat globule membrane, which makes the remaining milk fat globule membrane wrap around the fat globule, making the fat more likely to aggregate and thus become unstable.

[0155] The A0 value describes the milk's foaming ability; the higher the A0 value, the better the milk's foaming effect. A0 / A 30 The value describes the foam stability of milk after it has been foamed; the higher the value, the better the foam stability of the milk. As can be seen from Table 1, both removing polar lipids and changing the whey protein / casein ratio can significantly improve the foaming ability and foam stability compared with pure milk with the same indicators (Comparative Example 1). However, the foaming ability and stability are better when protein is used as the main surfactant than when milk fat is used as the main surfactant. At the same time, the higher the protein content and the higher the whey protein / casein ratio, the better the foaming effect.

[0156] As seen in Examples 1 and 2, removing polar lipids effectively improves the foaming ability of milk. Examples 2 and 3 & 4 show that, with the removal of polar lipids, low whey protein content or minimal denaturation significantly reduces the foaming effect of milk. Examples 3 and 5 demonstrate that while Comparative Example 5 showed a higher degree of removal of the milk fat globule membrane, reducing polar lipid content, this also resulted in the release of more free fatty acids from the fat globules, severely impacting foaming performance. Examples 4 and 6 & 7 show that both excessively high and low whey protein / casein ratios are detrimental to foaming. Excessively high whey protein content competes with polar lipids for foaming, leading to decreased foam stability; conversely, excessively low whey protein content fails to generate sufficient foam.

[0157] Table 2: Product Flavor Evaluation Table

[0158]

[0159]

[0160] As can be seen from the flavor evaluation table in Table 2, the milk obtained by removing polar lipids and changing the whey protein / casein ratio (Examples 1-6, Comparative Examples 2-5), except for Comparative Example 5, can effectively improve foam density and improve taste. Comparative Example 5, due to excessive removal of milk fat globule membrane, fat aggregation cannot be evenly distributed, which seriously affects the taste. Compared with Comparative Examples 2-4, Examples 1-2, without removing polar lipids, with an unsuitable whey protein / casein ratio, and with an unsuitable combination of sterilization process and the selection of the main surfactant in milk, all weaken the foam density.

[0161] Regarding blendability, at the same protein and fat content, changes in polar lipid content and the whey protein / casein ratio have little effect on blendability. However, increasing protein and fat content will significantly improve blendability. This is because higher protein content enhances the buffering capacity of milk, thus better mitigating the acidity from coffee, while fat enhances the aroma of milk. As for preference, the level of preference is mainly related to the density of the foam; the denser the foam, the higher the preference.

Claims

1. A method for preparing additive-free foaming milk; The additive-free foamed milk is ultra-high temperature pasteurized milk, and the preparation method of the additive-free foamed milk includes the following steps: 1-(1) Separate the raw milk to obtain light cream and skim milk; 1-(2) After cooling and crystallizing the cream, stirring and filtering, the filtering is performed using a filter screen with a pore size of 0.7-0.9μm to obtain cream with some milk fat globule membrane removed; 1-(3) The cream with part of the milk fat globule membrane removed is deacidified using an adsorption column filled with alkaline microcrystalline cellulose to obtain liquid A; 1-(4) The skim milk is separated by microfiltration to obtain liquid B and liquid C; 1-(5) Mix the liquid A, the liquid B and the liquid C in a certain proportion to obtain a first mixed liquid. The total mass of the first mixed liquid is 100%, the fat content is 3-5%, the protein content is 3-4.5%, and the mass ratio of whey protein to casein is 1:2-2:

1. 1-(6) After homogenizing and ultra-high temperature sterilization of the first mixture liquid, the additive-free foamed milk is obtained.

2. The preparation method according to claim 1, wherein, In step 1-(1), the raw milk includes one or a combination of cow's milk, sheep's milk and camel's milk.

3. The preparation method according to claim 1, wherein, In step 1-(1), the raw milk is raw milk that has been inspected, purified, and degassed.

4. The preparation method according to claim 3, wherein, The milk purification process involves purifying the milk at 2-60℃ with a centrifugal force of 4000-5000 g. And / or, the degassing is performed for 0.1-0.2 s at a temperature of -0.04 to -0.08 bar.

5. The preparation method according to claim 1, wherein, In steps 1-(2), the cooling crystallization temperature is 2-4℃ and the time is 10-20 h; And / or, in steps 1-(2), the stirring speed is 500-1000 rpm and the time is 20-30 min.

6. The preparation method according to claim 1, wherein, In steps 1-(4), the microfiltration separation uses a microfiltration membrane with a pore size of 90-100nm, an operating pressure of 1-3bar, and a temperature of 5-60℃.

7. The preparation method according to claim 1, wherein, In steps 1-(5), the mass ratio of whey protein to casein in the first mixture is 1:1-2:

1.

8. The preparation method according to claim 1, wherein, In steps 1-(6), the temperature of the homogenization is 50-60°C and the pressure is 170-210 bar.

9. The preparation method according to claim 1, wherein, In step 1-(6), the ultra-high temperature sterilization temperature is 132-160℃ and the time is 0.05-15s.

10. The preparation method according to claim 1, wherein, Step 1-(6) After ultra-high temperature sterilization, the process also includes cooling and filling steps to obtain the additive-free foamed milk.

11. An additive-free foaming milk, which is prepared by the method for preparing additive-free foaming milk according to any one of claims 1-6 and 8-10; The additive-free foamed milk is ultra-high temperature sterilized milk. Based on the total mass of the ultra-high temperature sterilized milk as 100%, the fat content is 3-5%, the protein content is 3-4.5%, and the mass ratio of whey protein to casein is 1:2-2:

1.

12. An additive-free foaming milk, which is prepared by the additive-free foaming milk preparation method according to claim 7; The additive-free foamed milk is ultra-high temperature sterilized milk. Based on the total mass of the ultra-high temperature sterilized milk as 100%, the fat content is 3-5%, the protein content is 3-4.5%, and the mass ratio of whey protein to casein is 1:1-2:1.

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