Hydrolyzed whey protein product and preparation method therefor

Abstract

The present invention relates to a whey protein product and a preparation method therefor. The product is derived from a whey protein-based protein composition, and the protein composition comprises at least a portion of whey protein degradation components, wherein protein components in the protein composition have a molecular weight distribution of: (i) the content of the protein component having a molecular weight of less than 5000 Da is 80-96% by mass; (ii) the content of the protein component having a molecular weight of 5000 Da to 10,000 Da is 0.5-10% by mass; and (iii) the content of protein component having a molecular weight of greater than 10,000 Da is 0-10% by mass, the content being the content of each of the three protein components in the total protein components based on dry weight.

Description

Hydrolyzed whey protein product and preparation method thereof Technical Field The present invention belongs to the field of food, and relates to a hydrolyzed protein dairy product and a preparation method thereof, in particular to a product containing hydrolyzed whey protein, which is suitable for infants with a high risk of milk protein allergy and can simultaneously provide a suitable osmotic pressure, and a preparation method thereof. Background Art Breast milk is the most ideal food for infants. It not only contains the nutrients that infants need for growth, but also has an osmotic pressure of 286-319 mOsm / kg H2O, which is consistent with the blood osmotic pressure of infants. When infants cannot be breastfed for various reasons, they need to eat infant formula to meet their normal growth. The most common infant formula on the market is produced with cow's milk as the base. Cow's milk protein in ordinary infant formula is the main factor of food allergy in infancy, among which β-lactoglobulin is the main allergen for infants. Hydrolyzed protein infant formula is easier to digest than intact protein because the intact protein is hydrolyzed into peptides and amino acids, and the content of allergens in milk protein (such as β-lactoglobulin) is reduced after hydrolysis. It is considered to be a better choice for infants at risk of milk protein allergy. Currently, research on hydrolyzed protein formula milk powder for preventing infants with milk protein allergies mainly focuses on reducing allergens and sensitization. Reference 1 discloses a partially hydrolyzed formula food for infant milk protein, which is obtained by enzymatically hydrolyzed whey protein and other raw materials. The hydrolyzed protein is prepared by a single enzyme hydrolysis process, and animal tests have verified that the food has an obvious anti-allergic effect. Cited document 2 discloses a partially hydrolyzed milk protein formula food for infants, which is prepared by a dry mixing process of hydrolyzed whey protein powder with other raw materials such as glucose syrup and vegetable fat powder. The molecular weight proportions of hydrolyzed whey protein powder in the product are as follows: 30-50% of peptides with a molecular weight less than 1000, 20-45% of peptides with a molecular weight between 1000-5000, 5-20% of peptides with a molecular weight between 5000-20000, and 10%-20% of peptides with a molecular weight greater than 20000. The food can prevent complications such as diarrhea, eczema, and asthma in infants caused by milk protein allergy. Despite the above research, there is still much room for further improvement in providing a powdered milk product suitable for various physiological conditions of infants and young children. References: Reference 1: CN113519686A Reference 2: CN110037115A Summary of the invention Problem that the invention aims to solve As mentioned above, whey protein has high nutritional value for infants and its amino acid composition meets the amino acid requirements of infants. However, intact proteins such as β-lactoglobulin in whey protein are a common allergen for infants. In order to reduce the risk of milk protein allergy in infants at high risk of allergies, hydrolyzed whey protein formula can be used to replace intact protein formula products. However, after enzymatic hydrolysis, protein is converted from a larger molecule into multiple peptides and amino acids with smaller molecular weights. In a solution of the same mass concentration, the total number of solute particles increases, and the osmotic pressure of the solution increases. Therefore, the osmotic pressure of a hydrolyzed protein solution of equal mass concentration is higher than that of a whole protein solution. In addition, the processing of infant formula foods requires the addition of a variety of ingredients, including minerals, lactose, and other raw materials that have a greater impact on osmotic pressure. Under conditions of similar lactose, ash, and protein content, the osmotic pressure of an equal concentration of hydrolyzed protein infant formula is greater than that of an ordinary whole protein infant formula. Studies have found the following phenomenon: most ordinary infant formula powders on the market focus more on nutritional value, but this results in the osmotic pressure of the standard solution after preparation being usually higher than that of breast milk. In addition, the osmotic pressure of the standard solution of hydrolyzed protein infant formula products is higher than that of ordinary infant formula powder, which is quite different from breast milk. Generally, emulsions or breast milk with an osmotic pressure exceeding 300mOsm / kg H2O are called hypertonic emulsions. Clinical studies have shown that due to incomplete kidney development during infancy, hypertonic emulsions can not only lead to the occurrence of hypernatremia and hyperazotemia in infants, but also have adverse effects on the kidneys of children. Feeding infants with isotonic solutions (260-299mOsm / kg H2O) is beneficial to protecting infant kidneys. The osmotic pressure is determined by the solute concentration of various substances in the emulsion. The osmotic pressure of hydrolyzed protein infant formula is affected by the molecular weight composition of hydrolyzed protein, the degree of hydrolysis, and other raw materials (such as carbohydrate types and mineral content). Commercially available hydrolyzed protein products pay more attention to whether hydrolysis can reduce allergens and sensitization, but do not pay attention to the influence of the degree of milk protein hydrolysis and the characteristics of product ingredients on the osmotic pressure of the product, resulting in a large difference between the osmotic pressure of the hydrolyzed product solution and breast milk. In the prior art such as References 1 and 2, although hydrolyzed protein infant formula products are proposed, no special attention is paid to the osmotic pressure of the solution after reconstitution. Therefore, based on the problems found in the prior art, the present invention proposes for the first time a protein composition containing hydrolyzed whey protein. By configuring a protein component derived from whey protein with a specific molecular weight distribution characteristic in the protein composition, when the protein composition is used to prepare formula milk powder, even if it is mixed with other formula raw materials, it can reduce allergic reactions and bad taste while giving the final formula milk powder a suitable osmotic pressure, thereby providing a formula milk product that is more suitable for the physiological characteristics of infants and young children. In addition, the present invention further provides a method for preparing the protein composition containing hydrolyzed whey protein and a formula dairy product. Solutions for solving problems The present invention believes that the above technical problems can be solved by implementing the following technical solutions: [1] The present invention first provides a whey protein-based protein composition, wherein at least part of the protein composition comprises a degraded component of whey protein, Wherein, the protein component in the protein composition has the following molecular weight distribution: (i) the content of protein components with a molecular weight of less than 5000 Da is 80% to 96% by mass; (ii) the content of protein components with a molecular weight of 5000Da to 10000Da is 0.5% to 10% by mass; (iii) The content of protein components with a molecular weight greater than 10,000 Da is 0 to 10% by mass. The content is the content of each of the three protein components in the total protein components based on dry weight. [2] The protein composition according to [1], wherein the degradation is enzymatic hydrolysis in the presence of an enzyme. [3] The protein composition according to [1] or [2], wherein all protein components in the protein composition are derived from whey protein. [4] The protein composition according to any one of [1] to [3], wherein the protein composition further comprises a carbohydrate component and optionally one or more of a fat component and a mineral salt, and the content of the carbohydrate is 30% by weight or less based on dry weight. [5] The method for preparing a protein composition according to any one of [1] to [4], wherein the method comprises: The step of enzymatically hydrolyzing the whey protein raw material in the presence of an enzyme, The whey protein raw material is selected from one or more of concentrated whey protein and isolated whey protein. [6] The method according to [5], wherein the enzyme is selected from one or more of alkaline protease, trypsin, pepsin, acid protease, neutral protease, protein deamidase, flavor protease, aminopeptidase, and carboxypeptidase. [7] The method according to [5] or [6], wherein the enzyme is a combination of alkaline protease and flavor protease. [8]. Furthermore, the present invention also provides a formula dairy product, wherein the dairy product comprises: (A) The protein composition according to any one of [1] to [4] above, and one or more of the following additional components: (B) Carbohydrate components, (C) Oil components, (D) Mineral salt components, (E) Other nutritional supplement components. [9]. The dairy product according to [8], wherein the (E) other nutritional supplement ingredients include one or more of vitamins, functional unsaturated fatty acids, choline substances, nucleotide substances, lutein substances, L-carnitine substances, probiotic substances, and inositol substances.

[0010] . The dairy product according to [8] or [9], wherein the (B) carbohydrate component includes lactose, and the amount of the additional lactose added is less than 50% by mass of the total mass of the formula dairy product.

[0011] . The dairy product according to any one of [8] to

[0010] , wherein the dairy product is an infant formula food product. Effects of the Invention By implementing the above technical solution, the present invention can achieve the following technical effects: 1) A protein composition derived from whey protein with a specific molecular weight distribution is obtained by degradation (enzymatic hydrolysis / hydrolysis). On the one hand, it can avoid excessive hydrolysis causing an increase in small molecular weight free amino acids, which brings about an undesirable taste such as bitterness. On the other hand, when the protein composition is used to mix with other ingredients to prepare a formula dairy product, it can play an effect of avoiding excessive increase in osmotic pressure. 2) The whey protein-based protein composition of the present invention and the dairy products prepared using the same are particularly suitable for the physical conditions of infants and young children, and are also suitable for children or adults with poor renal function due to various reasons. 3) Since the whey protein-based protein composition of the present invention has the effect of inhibiting osmotic pressure, when formula milk products are prepared using the whey protein-based protein composition, the addition or use of more nutritional substances can be tolerated compared to existing formula milk products. BRIEF DESCRIPTION OF THE DRAWINGS Figure 1: Flow chart of the preparation method of hydrolyzed protein dairy products. DETAILED DESCRIPTION Various exemplary embodiments, features and aspects of the present invention will be described in detail below. In order to better illustrate the present invention, numerous specific details are provided in the following specific embodiments. It should be understood by those skilled in the art that the present invention can be implemented without certain specific details. Unless otherwise stated, the units used in this specification are all international standard units, and the numerical values ​​and numerical ranges appearing in the present invention should be understood to include the inevitable systematic errors in industrial production. In this specification, the word "may" means both performing a certain process and not performing a certain process. In this specification, the numerical range expressed using "a numerical value A to a numerical value B" means a range including the endpoints A and B. In the present invention, a numerical range expressed using "above" or "below" means a numerical range including the number. In the present invention, the use of "optional" or "optionally" indicates that certain substances, components, execution steps, applied conditions and other factors are used or not used. In the present invention, "Da" is used to represent the unit of molecular weight "Dalton", that is, "Dalton". In the present invention, unless otherwise specified, the "normal temperature" used generally refers to a temperature of 23±2°C. In the present invention, unless otherwise stated, "%" used herein means weight or mass percentage. In the present invention, a mixed system of milk powder and water is used as a "solution", which may be a substantial microemulsion system. In this specification, "infants" are used to refer to a human group under the age of 3 years old. In this specification, for the convenience of describing fatty acid glycerides, the following characters are used to refer to different types of fatty acids: Ca: capric acid (C10:0); La: lauric acid (C12:0); M: myristic acid (C14:0); P: palmitic acid (C16:0); S: stearic acid (C18:0); O: oleic acid (C18:1); L: linoleic acid (C18:2); Ln: linolenic acid (C18:3); In this specification, for specific fatty acid esters, the above-mentioned characters are used in parallel combination to indicate the type of fatty acid glyceride, wherein the letter or letter combination in the middle position indicates the fatty acid at the 2nd position of glycerol. For example: OPO is used to represent 1,3-dioleyl-2-palmityl triglyceride; OPL is used to represent 1-oleyl-2-palmityl-3-linoleyl triglyceride; In this specification, the term "about" or "substantially" or "essentially" may mean that a value includes the standard deviation of the error of the device or method used to determine the value. The numerical ranges and parameters used to define the present invention are all approximate values, and the relevant values ​​in the specific embodiments have been presented as accurately as possible. However, any numerical value essentially inevitably contains the standard deviation caused by the aforementioned testing device or method. Therefore, unless otherwise explicitly stated, it should be understood that all ranges, quantities, values ​​and percentages used in the present invention are modified by "about". Here, "about" generally means that the standard deviation of the actual value and the theoretical model or theoretical data is within 3%, preferably 2%, and more preferably 1%. In the present invention, the references to "some specific / preferred embodiments", "other specific / preferred embodiments", "embodiments", etc., mean that the specific elements (e.g., features, structures, properties and / or characteristics) described in connection with the embodiments are included in at least one embodiment described herein, and may or may not exist in other embodiments. In addition, it should be understood that the elements may be combined in various embodiments in any suitable manner. The present invention primarily provides a whey protein-based protein composition, which is a composition particularly suitable for infants and young children at risk of milk protein allergy. Furthermore, based on the protein composition, a formula milk product is also provided, which has a good taste and an osmotic pressure of the formula milk close to the osmotic pressure of breast milk when prepared. The present invention is mainly obtained through the following insights: Prior art has been studied to some extent for the formula of infants and young children who are allergic to milk protein. By methods such as enzymolysis, whey protein is degraded into peptides and amino acids, so that the protein is easy to digest, and the content of allergens (such as β-lactoglobulin) in milk protein is reduced after being hydrolyzed. However, milk protein forms small molecule peptides and amino acids during hydrolysis, and there are two problems. One problem is that the above process will cause the appearance of bad taste or mouthfeel (terminal amino group, etc.), and the other problem is that the appearance of small molecules will cause the osmotic pressure of the prepared product to increase when used in the same formula and concentration. Through the research of the present invention, it has been found that by adjusting the degradation degree of whey protein, its protein molecular weight is distributed in a suitable range, not only bad flavor and mouthfeel problems can be avoided, but also the excessive increase problem of reducing to sensitization and suppressing the osmotic pressure of the prepared product can be played simultaneously. Furthermore, in some preferred embodiments, when preparing the above-mentioned whey protein-based protein composition, by optimizing the enzymatic hydrolysis process (such as the selection of enzymes, etc.), it is possible to ensure that the protein solution does not denature due to enzyme inactivation and heating, and it is possible to more easily control the molecular weight distribution of the hydrolyzed protein of the whey protein solution within a reasonable range. In addition, in some other preferred embodiments, the present invention has also found through experimental comparison that in dairy products, lactose has a greater effect on osmotic pressure, and adjusting the proportion of carbohydrates and replacing part of lactose with maltodextrin can not change the nutritional components and will not cause an increase in the osmotic pressure of the prepared milk solution. Therefore, while being able to fully supplement nutrients, it can also reduce the physical burden on infants and young children. <First aspect> In a first aspect of the present invention, a whey protein-based protein composition is provided, wherein the composition at least partially contains a degraded component of whey protein. In addition, the above protein composition may also optionally include (residual) undegraded whey protein, oil One or more of fat components, carbohydrate components, mineral salts, etc., preferably, carbohydrates, etc. In some preferred embodiments, the whey protein-based protein composition is entirely derived from degradation products of whey protein raw materials. (Whey protein raw materials) In principle, there is no particular limitation on the source of whey protein in the present invention. For example, the whey protein may be derived from various animal milks, such as cow's milk, goat's milk, horse's milk, camel's milk, etc. Preferably, the whey protein may be derived from cow's milk. There is no particular limitation on the method for separating or purifying whey from the animal milk. In some specific embodiments, the separation or purification means includes a defatting process to separate the fat component from the animal milk raw material. In principle, there is no particular limitation on the defatting method, which can be performed by centrifugation or the like. By the defatting process, at least 90% by mass, preferably 92% by mass, and more preferably 95% by mass of the total fat in the animal milk raw material is separated. In some specific embodiments, the above separation or purification also includes separating proteins from the raw milk (which has been defatted). The separation of proteins is mainly to separate casein. There is no particular limitation on the method of separating casein. For example, the pH of the raw milk can be adjusted by adding acidic substances to cause casein to coagulate and precipitate near its isoelectric point, thereby separating (acid whey); or, by optionally adding coagulants, leavening agents and other ingredients to the raw milk, the whey component (sweet whey) is separated while the cheese is formed. In addition, it is also possible to obtain a component containing whey protein by using a filter membrane with a suitable pore size to intercept and separate protein components of different molecular weights by membrane filtration. In some specific embodiments, above-mentioned separation or purification also comprises desalination and optional concentrated step, preferably, can after defatting, protein separation, the composition enriched with whey protein is carried out desalination and optional concentrated processing.For the processing of desalination, in principle also do not have special restrictions, for example, can use modes such as membrane filtration (nanofiltration (NF) and / or electrodialysis) to carry out.In some preferred embodiments, by desalination treatment, can be wherein more than 80 mass % inorganic salt, preferably more than 90 mass %, more preferably more than 95 mass % inorganic salt is removed.For the concentrated step, can carry out while desalination or afterwards, typically can use modes such as ultrafiltration, filter wash or reverse osmosis to obtain for example higher whey protein raw material of protein content. The whey protein-containing components obtained by the above-mentioned possible various process treatments can be further dried to obtain whey protein solids. Typically, solid whey protein powder can be obtained by spray drying or the like. In addition, the whey protein raw material of the present invention can be prepared by the above method or purchased from commercial products, such as various commercially available concentrated whey protein powders, isolated whey protein powders, whey protein liquids and other raw materials with high whey protein content. Preferably, the whey protein raw material of the present invention can use isolated whey protein. There is no particular limitation on the content of whey protein in the whey protein raw material of the present invention, which is related to the preparation method of the whey protein raw material. In some specific embodiments, the whey protein content in the whey protein raw material (based on the total dry weight of the whey protein raw material) can be 50% by weight or more, preferably 60-95% by weight, for example 65-90% by weight, 70-85% by weight, etc. (Degraded components of whey protein raw materials) The degradation components of whey protein of the present invention refer to products of whey protein hydrolysis in the presence or absence of enzymes, and these products have lower molecular weights, and may be peptide chains with a certain molecular weight or single amino acid molecules. In some preferred embodiments of the present invention, the degradation of the whey protein of the present invention is carried out by enzymatic hydrolysis in the presence of an enzyme to obtain an enzymatic hydrolysis product. In principle, there is no particular limitation on the enzymes that can be used for the enzymatic hydrolysis in the present invention. In some specific embodiments, it can be one or more of alkaline protease, trypsin, pepsin, acidic protease, neutral protease, protein deamidase, flavor protease, aminopeptidase, and carboxypeptidase. In some preferred embodiments, from the perspective of inhibiting bad flavor and taste and slowing down the effect of high-temperature enzyme inactivation treatment on protein components, the enzyme in the enzymatic hydrolysis of the present invention can be a combination of alkaline protease and flavor protease, and it has been found that such a combination of enzymes not only takes into account the above-mentioned flavor and taste, but also can easily obtain the degradation product with the desired molecular weight distribution of the present invention. More preferably, the ratio of the alkaline protease to the flavor protease can be 1:1 to 3. Regarding the dosage of the enzyme, in some specific embodiments, the total dosage of the enzyme may be 0.1% to 7% by mass, preferably 1.5% to 2.5% by mass, based on the total dry mass of the whey protein to be hydrolyzed. In some other specific embodiments, from the perspective of assisting enzymolysis, the enzymolysis can be further carried out in the presence of an acidity regulator. In principle, there is no particular restriction on the type of acidity regulator, as long as it complies with the provisions of food safety laws and regulations. Typically, one or more of alkali metal carbonates, bicarbonates, phosphates, (mono- or di-) hydrogen phosphates or alkali metal hydroxides can be cited. (Whey protein based protein composition) The whey protein-based protein composition of the present invention comprises at least the above-mentioned degradation components of whey protein. The whey protein-based protein composition of the present invention can be obtained by the following method: In the first embodiment, the above-mentioned whey protein raw material can be mixed with the degradation component of whey protein and other optional components to obtain the whey protein-based protein composition of the present invention; In the second embodiment, the whey protein-based protein composition of the present invention can be directly obtained by subjecting an undegraded or degradable whey protein raw material to the above-mentioned degradation method. Regardless of the method used to obtain the protein composition, the protein component therein has the following molecular weight distribution characteristics: (i) the content of the protein component having a molecular weight of less than 5000 Da is 80% to 96% by mass, preferably 85% to 90% by mass, for example 82%, 88%, 92% by mass, etc.; (ii) the content of the protein component with a molecular weight of 5000 Da to 10000 Da is 0.5% to 10% by mass, for example, 1%, 1.5%, 2%, 2.5%, 3%, 4%, 5%, 6%, 7%, 8% and 9% by mass; (iii) The content of the protein component having a molecular weight greater than 10,000 Da is 0 to 10% by mass, for example 8%, 7%, 6%, 5%, 4%, 3%, 2% and 1% by mass. The above contents are the contents of the three protein components respectively in the total protein components based on dry weight. In addition, the protein composition includes, in addition to the above-mentioned degradation components of whey protein, a carbohydrate component, and optionally one or more of a fat component and a mineral salt, and, based on dry weight, the content of the carbohydrate in the composition is 30% by mass or less, for example, 10 to 20% by mass, and the content of the fat component is 8% by mass or less, preferably 5% by mass or less. In some preferred embodiments of the present invention, from the perspective of preparation convenience, the whey protein-based protein composition of the present invention can be obtained by the second method described above. <Second Aspect> In a second aspect of the present invention, a formula dairy product and a preparation method thereof are provided. The formula dairy product of the present invention may be in a solid, liquid or semi-solid form, and preferably, the dairy product of the present invention may be in a powdered form. In some specific embodiments, the formula is an infant formula, a formula for children with renal insufficiency or an adult formula. Specifically, the dairy product of the present invention comprises: (A) The whey protein-based protein composition according to the first aspect, and in addition thereto one or more of the following additional components (i.e., these components do not come from the whey protein-based protein composition): (B) Carbohydrate component, (C) Oil component, (D) Mineral salt component, (E) Nutritional supplement component. (Carbohydrate content) There is no particular limitation on the type or source of the carbohydrate components added to the formula milk product of the present invention in principle, and the carbohydrates commonly used in formula milk products for specific groups of people, such as infants, can be used. In some specific embodiments, the carbohydrate component of the present invention mainly refers to sugar substances. The sugar substances are generally a general term for polyhydroxy aldehydes or polyhydroxy ketones and their polycondensates and certain derivatives, generally composed of three elements: carbon, hydrogen and oxygen. Sugar substances can be written as the empirical molecular formula: Cn(H2O) n . In the present invention, the carbohydrate substances may typically include monosaccharides, disaccharides, polysaccharides or oligosaccharides. Monosaccharides mainly include glucose, fructose and the like. Disaccharides, polysaccharides or oligosaccharides may include: sucrose, lactose, nitrosacetose, nitrotetrose, nitrosacetose, oligofructose, glucosaminoglycans, (malto)dextrin, and various forms of human milk oligosaccharides. In some preferred embodiments, the carbohydrates can be added in the form of dietary fiber. For dietary fiber substances, one or more of inulin, konjac flour, galacto-oligosaccharides, fructo-oligosaccharides, isomalto-oligosaccharides, soybean polysaccharides, cyclodextrin, maltodextrin, resistant dextrin, and soybean fiber can be cited. The present invention has found that, for the aqueous solution system of the dairy product of the present invention, in addition to the above-mentioned hydrolyzed whey protein, the lactose content also has an impact on the osmotic pressure. In some preferred embodiments of the present invention, the osmotic pressure of the preparation can be further inhibited by controlling the content of the carbohydrate lactose. Therefore, in a preferred embodiment of the present invention, the mass of the added lactose usually does not exceed 50% of the total mass of the formula milk product. More preferably, the added carbohydrates include lactose and maltose; in another preferred embodiment, based on the mass of the total added carbohydrate components in the formula milk product, the content of lactose can be adjusted to less than 5 times the content of maltose, for example, 0.25 to 4.5 times, 0.5 to 4 times, 1 to 3 times. Further, there is no particular limitation on the total content of carbohydrate components in the formula milk product of the present invention, and it can be configured with reference to the carbohydrate content in the art that is usually targeted at a specific population, such as infant formula milk powder products. In some specific embodiments, based on the total mass of the formula milk product (solids), the total content of the added carbohydrate components is 52 to 62% by mass, preferably 54 to 58% by mass. (Fat ingredients) There is no particular limitation on the type of the oil component added to the formula milk product of the present invention in principle, and fatty acid glycerides commonly used in infant formula milk powder products in the art can be used. For these glycerides, it can be obtained by extracting from plants or by artificial synthesis (transesterification). For transesterification method, glycerol and fatty acid can be carried out esterification reaction in the presence of a catalyst, or triglyceride and fatty acid in existing various sources can be carried out transesterification reaction in the presence of a (specific) catalyst (enzyme) to obtain. For the vegetable oil extracted from plants, required fatty acid glyceride can be obtained by mixing one or more vegetable oils extracted below. The vegetable oil includes one or more of rapeseed oil, soybean oil, sunflower seed oil, olive oil, coconut oil, sesame oil, corn oil, linseed oil, and camellia oil. For fatty acid glyceride of the present invention, mainly triglyceride. For these glycerides, for example OPL, OPO, MLCT, OOL, OPP, OLO, OLL, LPL, LPLn, OPLn, LPCa, OPCa etc. can be listed. The so-called "MLCT structured mixed ester" is a structural mixed ester with medium- and long-chain fatty acid triglycerides as the main components. "MLCT" refers to medium to long chain triglycerides, which are structural esters containing both medium-chain fatty acids (M) and long-chain fatty acids (L) on the glycerol skeleton, where medium-chain fatty acids refer to fatty acids containing 6 to 12 carbon atoms, and long-chain fatty acids refer to fatty acids with more than 12 carbon atoms. MLCT has the characteristics of both medium and long-chain fatty acids, and has the characteristics of supplementing essential fatty acids, quickly supplying energy and not causing fat accumulation. Common MLCTs are mainly OPLa, LPLa, OPCa, OLaO, OLaL, OMLa, SLaL and SLaO. From the perspective of being closer to the fat composition in breast milk, in some preferred embodiments, based on the total mass of the added oil components, the content of OPL triglycerides is 15-22% by mass; the content of OPO triglycerides is 10-16% by mass; and the content of medium-chain triglycerides is 25-36% by mass. Further, there is no particular limitation on the total content of the fat component in the present invention, and the content of the fat component commonly used in infant formula milk powder in the art can be used for configuration. In some specific embodiments, the total content of the added fat component is 22 to 29% by mass, preferably 24 to 27% by mass, based on the total mass of the formula milk product (solids). (Mineral salt ingredients) The mineral salt components that can be added to the formula dairy product of the present invention are mainly used to introduce calcium and other trace nutrients, such as iron, copper, manganese, zinc, cobalt, molybdenum, chromium, nickel, vanadium, fluorine, selenium, iodine, silicon, tin, etc. Furthermore, as for the content of mineral salts in formula milk products, as long as it complies with the provisions of laws and regulations, for example, those mineral salts commonly used in infant formula milk powder products in the art can be used. (Other nutritional supplement ingredients) There is no particular limitation on other nutritional supplement ingredients that can be added to the formula dairy product of the present invention, and they can be prepared according to existing methods in the art. In some specific embodiments, these supplement ingredients include: one or more selected from vitamins, choline substances, L-carnitine substances, inositol substances, nucleotide substances, lutein substances, probiotic substances, and functional unsaturated fatty acids. Vitamins include vitamin A, beta-carotene, vitamin D3, vitamin E, vitamin K, vitamin B1, vitamin B2, vitamin B6, vitamin B 12 , vitamin C, pantothenic acid, folic acid, niacin, and biotin. As probiotic substances, there may be cited bifidobacteria, lactobacillus probiotics and the like. Examples of the functional unsaturated fatty acid include arachidonic acid and docosahexaenoic acid. (Protein content of formula milk products) There is no particular restriction on the total content of protein components in the formula dairy product of the present invention, as long as it complies with the provisions of laws and regulations. In some specific embodiments, based on the total mass of the formula milk product, the content of the protein component in the milk product may be 20% by mass or less, for example, 10 to 14% by mass, preferably 11 to 13% by mass. Preferably, all of these protein components are derived from the above component (A). <Third Aspect> In a third aspect of the present invention, a method for preparing a formula dairy product is provided. The method comprises: Steps in whey protein degradation; The step of mixing to form a formulated dairy product. In some specific embodiments of the present invention, the step of degrading whey protein includes the steps of enzymatic hydrolysis of the whey protein solution and enzyme inactivation; the step of mixing to form a formula dairy product includes the steps of wet mixing, homogenization and sterilization, and optional evaporation concentration, spray drying, etc. In some preferred embodiments of the present invention, all the protein components in the formula milk product are derived from the degradation of the whey protein. (Steps of whey protein degradation) In the preparation method of the present invention, preferably, the degradation step is carried out by enzymatic hydrolysis of a solution formed by a whey protein raw material, and the step of enzymatic hydrolysis of the whey protein solution mainly involves hydrolyzing the whey protein solution into water by a specific enzyme. The process of protein solution. Specifically, in the step of enzymatically hydrolyzing the whey protein solution, the pH value is adjusted to 6.0-9.0 using an acidity regulator and the whey protein solution is enzymatically hydrolyzed at a temperature T1. The temperature T1 may be 40 to 70° C., preferably 50 to 60° C., in some specific embodiments. At this temperature, the enzyme has a high activity, and the enzymolysis time may be 45 to 180 min, preferably 90 to 120 min, in some specific embodiments. Under this time, the enzyme can decompose the whey protein into hydrolyzed proteins with suitable molecular weight distribution. Regarding the protein concentration in the whey protein solution, in some specific embodiments, it can be 4% to 15% by mass, preferably 7% to 9% by mass. Regarding the dry matter concentration in the whey protein solution, in some specific embodiments, it can be 6% to 17% by mass, preferably 9% to 11% by mass. In addition, the acidity regulator, in some specific embodiments, can be one or more of food-grade sodium bicarbonate, sodium citrate, potassium carbonate, disodium hydrogen phosphate, dipotassium hydrogen phosphate, potassium hydroxide, sodium hydroxide, etc. For the use of enzymes, they can be selected and used with reference to the contents disclosed above. (Enzyme inactivation step) After the enzymatic hydrolysis step, an enzyme inactivation step is performed to terminate the hydrolysis reaction to obtain a protein hydrolyzate. Specifically, in the step of inactivating the enzyme, the enzyme is inactivated at temperature T2, and the inactivation temperature and time are selected according to the enzyme with the highest requirement, and it is necessary to ensure that the protein solution does not denature due to the heating of the enzyme inactivation. In some specific embodiments of the present invention, the temperature T2 can be 90 to 130° C., preferably 105 to 115° C., and the enzyme inactivation time can be 15 s to 15 min, preferably 10 to 60 s. (Wet mixing steps) After the protein hydrolyzate is treated with enzyme inactivation, it can be wet mixed with other main components to obtain a wet mixed mixture. The main components mentioned here may refer to the components (B) to (E) contained in the second aspect. It should be noted that the probiotics, functional unsaturated fatty acids and other substances in component (E) can also be mixed into the mixed system after evaporation concentration and spray drying as described below when necessary to ensure the activity of these components. In some specific embodiments, the wet mixing is carried out at 40-65°C, preferably at 50-60°C. (Homogenization step) After the wet mixed mixture is obtained, it can be homogenized to obtain an emulsion system with an ideal particle size. In some specific embodiments, the homogenization is carried out under a pressure of 15 to 45 MPa, preferably under a pressure of 25 to 35 MPa. (Sterilization steps) The homogenized mixture can be sterilized by sterilization. There is no particular limitation on the specific method of sterilization. The mixture can be treated by conventional pasteurization methods, such as hot water steam (direct steam injection - DSI). In some specific embodiments, the sterilization temperature may be 80 to 120°C, preferably 85 to 90°C. The sterilization time can be adjusted according to the sterilization temperature. The sterilization time required at high temperature is relatively short, and the sterilization time required at low temperature is relatively long. In some specific embodiments of the present invention, the sterilization time can be 3s to 10min, preferably 15 to 35s. (Other steps) The mixture obtained after sterilization can be subjected to other optional subsequent treatments to finally obtain the formula milk product of the present invention. In some specific embodiments, the other steps may include one or more of evaporation concentration, spray drying, filling, etc. (Preparation characteristics) The formula milk product of the present invention is preferably a reconstituted milk powder product. When the product is prepared in a standard manner, the osmotic pressure of the obtained solution is 265-300 mOsm / kg, and the preferred osmotic pressure is 285-300 mOsm / kg. The method for detecting the osmotic pressure of the formula milk product of the present invention can adopt the osmotic pressure detection method commonly used in the art, which can be listed as the freezing point method or the dew point method. The freezing point method uses the measurement of the freezing point depression of the solution to indirectly determine its osmotic pressure molar concentration, and the instrument that can be used is the German GONOTEC 3000-D osmometer, etc.; the dew point method uses the measurement of the vapor pressure depression of the solution to indirectly determine its osmotic pressure molar concentration, and the instrument that can be used is the American wescor5600, etc. (Typical preparation process of formula dairy products) The formula milk powder uses the following components in parts by weight (dry weight): 150-400 parts of lactose, 100-300 parts of maltodextrin, 150-350 parts of vegetable blending oil, 80-250 parts of the hydrolyzed whey protein powder of the present invention, 20-45 parts of macro minerals, 1-20 parts of enzyme preparation, 0.05-6 parts of vitamins, 0.05-5 parts of trace minerals, 0.5-10 parts of arachidonic acid, 0.5-8 parts of docosahexaenoic acid, 0.5-5 parts of choline chloride, 0.2-3 parts of nucleotides, 0.05-0.5 parts of inositol, 0.01-0.4 parts of L-carnitine, and 0.0001-0.3 parts of lutein. The enzyme preparation includes two enzymes, namely alkaline protease Conc.BG (enzyme activity 12.5AU-A / g) and flavor protease Flavourzyme 500MG (aminopeptidase, enzyme activity 500LAPU / g). The process is shown in Figure 1 Step 1: Preparation of whey protein solution The protein liquid can be made from raw materials with high whey protein content such as concentrated whey protein powder, isolated whey protein powder, and whey protein liquid. The protein concentration in the protein liquid is 4% to 15%, and the dry matter concentration is 6 to 17%. Step 2: Enzymatic hydrolysis Acidity regulators are added, including but not limited to one or more of food-grade sodium bicarbonate, sodium citrate, potassium carbonate, disodium hydrogen phosphate, dipotassium hydrogen phosphate, potassium hydroxide, sodium hydroxide, etc., to adjust the pH value to 6.0-9.0. Proteases are added at 0.1-5% (w / w) of the protein content in the protein solution, including but not limited to one or more of alkaline protease, trypsin, pepsin, acid protease, and neutral protease. Flavor proteases are added at 0.1-7% (w / w) of the protein content in the protein solution, including but not limited to one or more of protein deamidase, flavor protease, aminopeptidase, and carboxypeptidase, and enzymolysis is performed at 40-70°C for 45-180 minutes. Step 3: Inactivate enzyme 90~130℃, 15s~15min. The enzyme inactivation parameters are determined according to the enzyme with the highest inactivation temperature and time requirements. At the same time, it is necessary to ensure that the protein solution does not denature due to the inactivation heating. Step 4: Mixing After the enzyme is inactivated, the temperature is lowered to 40-65°C, and lactose, maltodextrin, vegetable blending oil, vitamins, macro minerals, trace minerals, choline chloride, nucleotides, inositol, L-carnitine, lutein, docosahexaenoic acid, and arachidonic acid are mixed with the mixture, and the mixture is pumped into a wet mixing storage tank. Step 5: Homogenize Two-stage homogenization is adopted, and the homogenization pressure is 15~45MPa. Step 6: Bus sterilization 80~120℃, sterilization for 3s-10min. Step 7: Evaporation and concentration The material in the wet mix storage tank is pumped into the evaporator balance, and then sterilized and concentrated by the evaporator and pumped into the concentrated milk tank. Step 8: Spray drying and packaging The material in the concentrated milk tank passes through the preheater and high-pressure pump and is sprayed into the drying tower under high pressure. It is then transported to the packaging machine for packaging through the fluidized bed, vibrating screen and dense phase conveyor. The formula milk product obtained by the method of the present invention can be widely applicable to various groups of people, especially, it is suitable for infants and young children to eat. Example The embodiments of the present invention are described in detail below with reference to the examples. If no specific conditions are specified in the examples, the conditions are carried out according to conventional conditions or the conditions recommended by the manufacturer. If the manufacturer of the reagents or instruments is not specified, they are all conventional products that can be obtained commercially. Among them, the alkaline protease Conc.BG (enzyme activity 12.5AU-A / g) and flavor protease Flavourzyme500MG (aminopeptidase, enzyme activity 500LAPU / g) are produced by Novozymes, and the instant concentrated whey protein powder WPC80 is produced by Angepu. Example 1 Step 1: Preparation of protein solution: Instant concentrated whey protein powder WPC80 is preferably used as raw material to prepare protein solution, wherein the protein concentration of the protein solution is 8% and the dry matter concentration is 10%. The solution is fully dissolved and hydrated. Step 2: Enzyme hydrolysis. Add food-grade potassium hydroxide solution to adjust the pH value to 7.0±0.5. Add enzyme preparation according to 2.0% of the protein content in the protein solution, wherein the enzyme preparation composition is alkaline protease Conc.BG: flavor protease Flavourzyme 500MG at a ratio of 1:2, and stir the enzymolysis at 55±2°C for 90±10 minutes. Step 3: Inactivate the enzyme by indirect heating at 110±2℃ for 20±2s. Step 4: Mixing. After the enzyme is inactivated, the temperature is lowered to 55°C to obtain 155 parts of whey protein hydrolysate by dry weight. All other materials are mixed with it and the material liquid is pumped into a wet mixing storage tank. Raw material addition amount: 380 parts of lactose, maltodextrin 170 parts, vegetable blending oil 250 parts, macro minerals 30 parts, vitamins 4 parts, trace minerals 5 parts, arachidonic acid 2 parts, docosahexaenoic acid 1.3 parts, choline chloride 1.8 parts, nucleotides 0.8 parts, inositol 0.07 parts, L-carnitine 0.025 parts, lutein 0.005 parts. Step 5: Homogenization: Use two-stage homogenization with a homogenization pressure of 25±2Mpa. Step 6: Sterilization: 90±2℃, 19±2s. Step 7: Evaporation and concentration. The material in the wet mix storage tank is pumped into the evaporator balance, and then sterilized and concentrated by the evaporator and pumped into the concentrated milk tank. Step 8: Spray drying and filling. The material in the concentrated milk tank passes through the preheater and high-pressure pump and is sprayed into the drying tower at high pressure. It is then transported to the packaging machine for packaging through the fluidized bed, vibrating screen and dense phase. Example 2 Step 1: Preparation of protein solution: Instant concentrated whey protein powder WPC80 is preferably used as raw material to prepare protein solution, wherein the protein concentration of the protein solution is 8% and the dry matter concentration is 10%. The solution is fully dissolved and hydrated. Step 2: Enzyme hydrolysis. Add food-grade potassium hydroxide solution to adjust the pH value to 7.0±0.5. Add enzyme preparation according to 2.5% of the protein content in the protein solution, wherein the enzyme preparation composition is alkaline protease Conc.BG: flavor protease Flavourzyme 500MG at a ratio of 1:2, and stir the enzymolysis at 55±2°C for 90±10 minutes. Step 3: Inactivate the enzyme by indirect heating at 110±2℃ for 20±2s. Step 4, mixing. After the enzyme is inactivated, the temperature is lowered to 55°C to obtain a whey protein hydrolyzate with a dry weight of 155 parts, all other materials are mixed with it, and the material liquid is pumped into a wet mixing storage tank. The amount of raw materials added is 380 parts of lactose, 170 parts of maltodextrin, 250 parts of vegetable blending oil, 30 parts of macro minerals, 4 parts of vitamins, 5 parts of trace minerals, 2 parts of arachidonic acid, 1.3 parts of docosahexaenoic acid, 1.8 parts of choline chloride, 0.8 parts of nucleotides, 0.07 parts of inositol, 0.025 parts of L-carnitine, and 0.005 parts of lutein. Step 5: Homogenization: Use two-stage homogenization with a homogenization pressure of 25±2Mpa. Step 6: Sterilization: 90±2℃, 19±2s. Step 7: Evaporation and concentration. The material in the wet mix storage tank is pumped into the evaporator balance, and then sterilized and concentrated by the evaporator and pumped into the concentrated milk tank. Step 8: Spray drying and filling. The material in the concentrated milk tank passes through the preheater and high-pressure pump and is sprayed into the drying tower at high pressure. It is then transported to the packaging machine for packaging through the fluidized bed, vibrating screen and dense phase. Example 3 Step 1: Preparation of protein solution: Instant concentrated whey protein powder WPC80 is preferably used as raw material to prepare protein solution, wherein the protein concentration of the protein solution is 8% and the dry matter concentration is 10%. The solution is fully dissolved and hydrated. Step 2: Enzyme hydrolysis. Add food-grade potassium hydroxide solution to adjust the pH value to 7.0±0.5. Add enzyme preparation according to 2.0% of the protein content in the protein solution, wherein the enzyme preparation composition is alkaline protease Conc.BG: flavor protease Flavourzyme 500MG at a ratio of 3:7, and stir the enzymolysis at 55±2°C for 90±10 minutes. Step 3: Inactivate the enzyme by indirect heating at 110±2℃ for 20±2s. Step 4: Mixing. After the enzyme is inactivated, the temperature is lowered to 55°C to obtain 155 parts of whey protein hydrolysate by dry weight. All materials are mixed with it, and the liquid is pumped into the wet mixing storage tank. Raw material addition amount: 380 parts of lactose, 170 parts of maltodextrin, 250 parts of vegetable blending oil, 30 parts of macro minerals, 4 parts of vitamins, 5 parts of trace minerals, 2 parts of arachidonic acid, 1.3 parts of docosahexaenoic acid, 1.8 parts of choline chloride, 0.8 parts of nucleotides, 0.07 parts of inositol, 0.025 parts of L-carnitine, and 0.005 parts of lutein. Step 5: Homogenization: Use two-stage homogenization with a homogenization pressure of 25±2Mpa. Step 6: Sterilization: 90±2℃, 19±2s. Step 7: Evaporation and concentration. The material in the wet mix storage tank is pumped into the evaporator balance, and then sterilized and concentrated by the evaporator and pumped into the concentrated milk tank. Step 8: Spray drying and filling. The material in the concentrated milk tank passes through the preheater and high-pressure pump and is sprayed into the drying tower at high pressure. It is then transported to the packaging machine for packaging through the fluidized bed, vibrating screen and dense phase. Example 4 Step 1: Preparation of protein solution: Instant concentrated whey protein powder WPC80 is preferably used as raw material to prepare protein solution, wherein the protein concentration of the protein solution is 8% and the dry matter concentration is 10%. The solution is fully dissolved and hydrated. Step 2: Enzyme hydrolysis. Add food-grade potassium hydroxide solution to adjust the pH value to 7.0±0.5. Add enzyme preparation according to 2.5% of the protein content in the protein solution, wherein the enzyme preparation composition is alkaline protease Conc.BG: flavor protease Flavourzyme 500MG at a ratio of 3:7, and stir the enzymolysis at 55±2°C for 90±10 minutes. Step 3: Inactivate the enzyme by indirect heating at 110±2℃ for 20±2s. Step 4, mixing. After the enzyme is inactivated, the temperature is lowered to 55°C to obtain a whey protein hydrolyzate with a dry weight of 155 parts, all other materials are mixed with it, and the material liquid is pumped into a wet mixing storage tank. The amount of raw materials added is 380 parts of lactose, 170 parts of maltodextrin, 250 parts of vegetable blending oil, 30 parts of macro minerals, 4 parts of vitamins, 5 parts of trace minerals, 2 parts of arachidonic acid, 1.3 parts of docosahexaenoic acid, 1.8 parts of choline chloride, 0.8 parts of nucleotides, 0.07 parts of inositol, 0.025 parts of L-carnitine, and 0.005 parts of lutein. Step 5: Homogenization: Use two-stage homogenization with a homogenization pressure of 25±2Mpa. Step 6: Sterilization: 90±2℃, 19±2s. Step 7: Evaporation and concentration. The material in the wet mix storage tank is pumped into the evaporator balance, and then sterilized and concentrated by the evaporator and pumped into the concentrated milk tank. Step 8: Spray drying and filling. The material in the concentrated milk tank passes through the preheater and high-pressure pump and is sprayed into the drying tower at high pressure. It is then transported to the packaging machine for packaging through the fluidized bed, vibrating screen and dense phase. Example 5 Step 1: Preparation of protein solution: Instant concentrated whey protein powder WPC80 is preferably used as raw material to prepare protein solution, wherein the protein concentration of the protein solution is 8% and the dry matter concentration is 10%. The solution is fully dissolved and hydrated. Step 2: Enzyme hydrolysis. Add food-grade potassium hydroxide solution to adjust the pH value to 7.0±0.5. Add enzyme preparation according to 2.0% of the protein content in the protein solution, wherein the enzyme preparation composition is alkaline protease Conc.BG: flavor protease Flavourzyme 500MG at a ratio of 3:7, and stir the enzymolysis at 55±2°C for 90±10 minutes. Step 3: Inactivate the enzyme by indirect heating at 110±2℃ for 20±2s. Step 4, mixing. After the enzyme is inactivated, the temperature is lowered to 55°C to obtain a whey protein hydrolyzate with a dry weight of 155 parts, all other materials are mixed with it, and the material liquid is pumped into a wet mixing storage tank. Raw material addition amount: 300 parts of lactose, 250 parts of maltodextrin, 250 parts of vegetable blending oil, 30 parts of macro minerals, 4 parts of vitamins, 5 parts of trace minerals, 2 parts of arachidonic acid, 1.3 parts of docosahexaenoic acid, 1.8 parts of choline chloride, 0.8 parts of nucleotides, 0.07 parts of inositol, 0.025 parts of L-carnitine, and 0.005 parts of lutein. Step 5: Homogenization: Use two-stage homogenization with a homogenization pressure of 25±2Mpa. Step 6: Sterilization: 90±2℃, 19±2s. Step 7: Evaporation and concentration. The material in the wet mix storage tank is pumped into the evaporator balance, and then sterilized and concentrated by the evaporator and pumped into the concentrated milk tank. Step 8: Spray drying and filling. The material in the concentrated milk tank passes through the preheater and high-pressure pump and is sprayed into the drying tower at high pressure. It is then transported to the packaging machine for packaging through the fluidized bed, vibrating screen and dense phase. Example 6 Step 1: Preparation of protein solution: Instant concentrated whey protein powder WPC80 is preferably used as raw material to prepare protein solution, wherein the protein concentration of the protein solution is 8% and the dry matter concentration is 10%. The solution is fully dissolved and hydrated. Step 2: Enzyme hydrolysis. Add food-grade potassium hydroxide solution to adjust the pH value to 7.0±0.5. Add enzyme preparation according to 2.5% of the protein content in the protein solution, wherein the enzyme preparation composition is alkaline protease Conc.BG: flavor protease Flavourzyme 500MG at a ratio of 3:7, and stir the enzymolysis at 55±2°C for 90±10 minutes. Step 3: Inactivate the enzyme by indirect heating at 110±2℃ for 20±2s. Step 4, mixing. After the enzyme is inactivated, the temperature is lowered to 55°C to obtain a whey protein hydrolyzate with a dry weight of 155 parts, all other materials are mixed with it, and the material liquid is pumped into a wet mixing storage tank. Raw material addition amount: 300 parts of lactose, 250 parts of maltodextrin, 250 parts of vegetable blending oil, 30 parts of macro minerals, 4 parts of vitamins, 5 parts of trace minerals, 2 parts of arachidonic acid, 1.3 parts of docosahexaenoic acid, 1.8 parts of choline chloride, 0.8 parts of nucleotides, 0.07 parts of inositol, 0.025 parts of L-carnitine, and 0.005 parts of lutein. Step 5: Homogenization: Use two-stage homogenization with a homogenization pressure of 25±2Mpa. Step 6: Sterilization: 90±2℃, 19±2s. Step 7: Evaporation and concentration. The material in the wet mix storage tank is pumped into the evaporator balance, and then sterilized and concentrated by the evaporator and pumped into the concentrated milk tank. Step 8: Spray drying and filling. The material in the concentrated milk tank passes through the preheater and high-pressure pump and is sprayed into the drying tower at high pressure. It is then transported to the packaging machine for packaging through the fluidized bed, vibrating screen and dense phase. Example 7 Step 1: Preparation of protein solution: Instant concentrated whey protein powder WPC80 is preferably used as raw material to prepare protein solution, wherein the protein concentration of the protein solution is 8% and the dry matter concentration is 10%. The solution is fully dissolved and hydrated. Step 2: Enzyme hydrolysis. Add food-grade potassium hydroxide solution to adjust the pH value to 7.0±0.5. Add enzyme preparation according to 2.0% of the protein content in the protein solution, wherein the enzyme preparation composition is alkaline protease Conc.BG: flavor protease Flavourzyme 500MG at a ratio of 1:2, and stir the enzymolysis at 55±2°C for 90±10 minutes. Step 3: Inactivate the enzyme by indirect heating at 110±2℃ for 20±2s. Step 4, mixing. After the enzyme is inactivated, the temperature is lowered to 55°C to obtain a whey protein hydrolyzate with a dry weight of 155 parts, all other materials are mixed with it, and the material liquid is pumped into a wet mixing storage tank. Raw material addition amount: 300 parts of lactose, 250 parts of maltodextrin, 250 parts of vegetable blending oil, 30 parts of macro minerals, 4 parts of vitamins, 5 parts of trace minerals, 2 parts of arachidonic acid, 1.3 parts of docosahexaenoic acid, 1.8 parts of choline chloride, 0.8 parts of nucleotides, 0.07 parts of inositol, 0.025 parts of L-carnitine, and 0.005 parts of lutein. Step 5: Homogenization: Use two-stage homogenization with a homogenization pressure of 25±2Mpa. Step 6: Sterilization: 90±2℃, 19±2s. Step 7: Evaporation and concentration. The material in the wet mix storage tank is pumped into the evaporator balance, and then sterilized and concentrated by the evaporator and pumped into the concentrated milk tank. Step 8: Spray drying and filling. The material in the concentrated milk tank passes through the preheater and high-pressure pump and is sprayed into the drying tower at high pressure. It is then transported to the packaging machine for packaging through the fluidized bed, vibrating screen and dense phase. Example 8 Step 1: Preparation of protein solution: Instant concentrated whey protein powder WPC80 is preferably used as raw material to prepare protein solution, wherein the protein concentration of the protein solution is 8% and the dry matter concentration is 10%. The solution is fully dissolved and hydrated. Step 2: Enzyme hydrolysis. Add food-grade potassium hydroxide solution to adjust the pH value to 7.0±0.5. Add enzyme preparation according to 2.5% of the protein content in the protein solution, wherein the enzyme preparation composition is alkaline protease Conc.BG: flavor protease Flavourzyme 500MG at a ratio of 1:2, and stir the enzymolysis at 55±2°C for 90±10 minutes. Step 3: Inactivate the enzyme by indirect heating at 110±2℃ for 20±2s. Step 4, mixing. After the enzyme is inactivated, the temperature is lowered to 55°C to obtain a whey protein hydrolyzate with a dry weight of 155 parts, all other materials are mixed with it, and the material liquid is pumped into a wet mixing storage tank. Raw material addition amount: 300 parts of lactose, 250 parts of maltodextrin, 250 parts of vegetable blending oil, 30 parts of macro minerals, 4 parts of vitamins, 5 parts of trace minerals, 2 parts of arachidonic acid, 1.3 parts of docosahexaenoic acid, 1.8 parts of choline chloride, 0.8 parts of nucleotides, 0.07 parts of inositol, 0.025 parts of L-carnitine, and 0.005 parts of lutein. Step 5: Homogenization: Use two-stage homogenization with a homogenization pressure of 25±2Mpa. Step 6: Sterilization: 90±2℃, 19±2s. Step 7: Evaporation and concentration. The material in the wet mix storage tank is pumped into the evaporator balance, and then sterilized and concentrated by the evaporator and pumped into the concentrated milk tank. Step 8: Spray drying and filling. The material in the concentrated milk tank passes through the preheater and high-pressure pump and is sprayed into the drying tower at high pressure. It is then transported to the packaging machine for packaging through the fluidized bed, vibrating screen and dense phase. Comparative Example 1 Step 1: Preparation of protein solution: Instant concentrated whey protein powder WPC80 is preferably used as raw material to prepare protein solution, wherein the protein concentration of the protein solution is 8% and the dry matter concentration is 10%. The solution is fully dissolved and hydrated. Step 2: Enzymatic hydrolysis. Add food-grade potassium hydroxide solution to adjust the pH to 7.0±0.5. Add Flavourzyme 500MG according to 2.0% of the protein content in the protein solution, and stir and enzymolyze at 55±2°C for 90±10 minutes. Step 3: Inactivate the enzyme by indirect heating at 110±2℃ for 20±2s. Step 4: Mixing. After the enzyme is inactivated, the temperature is lowered to 55°C, and all other materials are mixed with the mixture, and the mixture is pumped into a wet mixing storage tank. Raw material addition amount: 380 parts of lactose, 170 parts of maltodextrin, 250 parts of vegetable blending oil, 30 parts of macro minerals, 4 parts of vitamins, 5 parts of trace minerals, 2 parts of arachidonic acid, 1.3 parts of docosahexaenoic acid, 1.8 parts of choline chloride, 0.8 parts of nucleotides, 0.07 parts of inositol, 0.025 parts of L-carnitine, and 0.005 parts of lutein. Step 5: Homogenization: Use two-stage homogenization with a homogenization pressure of 25±2Mpa. Step 6: Sterilization: 90±2℃, 19±2s. Step 7: Evaporation and concentration. The material in the wet mix storage tank is pumped into the evaporator balance, and then sterilized and concentrated by the evaporator and pumped into the concentrated milk tank. Step 8: Spray drying and filling. The material in the concentrated milk tank passes through the preheater and high-pressure pump and is sprayed into the drying tower at high pressure. It is then transported to the packaging machine for packaging through the fluidized bed, vibrating screen and dense phase. Comparative Example 2 Step 1: Preparation of protein solution: Instant concentrated whey protein powder WPC80 is used as raw material to prepare protein solution, wherein the protein concentration of the protein solution is 8% and the dry matter concentration is 10%. The solution is fully dissolved and hydrated. Step 2: Enzyme hydrolysis: Add food-grade potassium hydroxide solution to adjust the pH value to 7.0±0.5. Add enzyme preparation according to 2.0% of the protein content in the protein solution, wherein the enzyme preparation composition is alkaline protease Conc.BG, and stir at 50°C for enzymolysis for 50 minutes. Step 3: Inactivate the enzyme by indirect heating at 110±2℃ for 20±2s. Step 4: Mixing. After the enzyme is inactivated, the temperature is lowered to 55°C, and all other materials are mixed with the mixture, and the mixture is pumped into a wet mixing storage tank. Raw material addition amount: 380 parts of lactose, 170 parts of maltodextrin, 250 parts of vegetable blending oil, 30 parts of macro minerals, 4 parts of vitamins, 5 parts of trace minerals, 2 parts of arachidonic acid, 1.3 parts of docosahexaenoic acid, 1.8 parts of choline chloride, 0.8 parts of nucleotides, 0.07 parts of inositol, 0.025 parts of L-carnitine, and 0.005 parts of lutein. Step 5: Homogenization: Use two-stage homogenization with a homogenization pressure of 25±2Mpa. Step 6: Sterilization: 90±2℃, 19±2s. Step 7: Evaporation and concentration: The material in the wet mix storage tank is pumped into the evaporator balance, and after sterilization and concentration by the evaporator, it is pumped into the concentrated milk tank. Step 8: Spray drying and filling. The material in the concentrated milk tank passes through the preheater and high-pressure pump and is sprayed into the drying tower at high pressure. It is then transported to the packaging machine for packaging through the fluidized bed, vibrating screen and dense phase. Reference example Step 1: Add different enzyme dosages to concentrated whey protein powder WPC80 for hydrolysis, compare molecular weight distribution, and standard dilution osmotic pressure) Step 1: Preparation of protein solution: Instant concentrated whey protein powder WPC80 is preferably used as raw material to prepare protein solution, wherein the protein concentration of the protein solution is 8% and the dry matter concentration is 10%. The solution is fully dissolved and hydrated. Step 2: Enzyme hydrolysis. Add food-grade potassium hydroxide solution to adjust the pH value to 7.0±0.5. Add enzyme preparation according to 2.0% of the protein content in the protein solution, wherein the enzyme preparation composition is alkaline protease Conc.BG: flavor protease Flavourzyme 500MG at a ratio of 3:7, and stir the enzymolysis at 55±2°C for 90±10 minutes. Step 3: Inactivate the enzyme by indirect heating at 110±2℃ for 20±2s. Step 4: Mixing. After the enzyme is inactivated, the temperature is lowered to 55°C, and all other materials are mixed with the mixture, and the mixture is pumped into a wet mixing storage tank. Raw material addition amount: 550 parts of lactose, 250 parts of vegetable blending oil, 30 parts of macro minerals, 4 parts of vitamins, 5 parts of trace minerals, 2 parts of arachidonic acid, 1.3 parts of docosahexaenoic acid, 1.8 parts of choline chloride, 0.8 parts of nucleotides, 0.07 parts of inositol, 0.025 parts of L-carnitine, and 0.005 parts of lutein. Step 5: Homogenization: Use two-stage homogenization with a homogenization pressure of 25±2Mpa. Step 6: Sterilization: 90±2℃, 19±2s. Step 7: Evaporation and concentration: The material in the wet mix storage tank is pumped into the evaporator balance, and after sterilization and concentration by the evaporator, it is pumped into the concentrated milk tank. Step 8: Spray drying and filling. The material in the concentrated milk tank passes through the preheater and high-pressure pump and is sprayed into the drying tower at high pressure. It is then transported to the packaging machine for packaging through the fluidized bed, vibrating screen and dense phase. The molecular weight distribution, bitterness and osmotic pressure of the milk powder products obtained in the above examples and comparative examples were tested. The protein molecular weight distribution was tested using GB / T22492-2008 Appendix A GPC / UV and Novozymes' own testing method improved with reference to the national standard; Bitterness Evaluation Criteria Using the sensory evaluation method, 12.9g of dry powder was weighed and added into 90mL of warm water at about 50℃, and stirred thoroughly to dissolve it. The milk was prepared and provided to 15 professional tasters for evaluation. According to the method of GB / T 12312-2012 "Sensory Analysis - Determination of Taste Sensitivity", crystalline caffeine (monohydrate, molecular weight 212.12) was prepared into different concentrations, as shown in Table 1. According to this scoring standard, the milk was tasted and the bitterness value was evaluated by comparing with the standard. Finally, the average value was taken as the final bitterness value of the milk, ranging from 1 to 6 for no bitterness to very bitterness; Table 1 Bitterness standard of sensory evaluation Standard solution preparation method Weigh 12.9 g of dry powder and add it into 90 mL of warm water at about 50°C, stirring thoroughly to dissolve it. The osmotic pressure of the standard preparation solution was tested using an ice point osmometer. The specific results are shown in Table 2: Table 2: Compared with Example 1 and Example 8, the reference example used an extraordinary amount of lactose, and the results showed that lactose had a significant effect on osmotic pressure, and therefore did not meet the requirements of isotonic solution (isotonic solution 260-299mOsm / kg H2O). The molecular weight distribution of the protein in Comparative Example 1 is not within the scope of the present invention. Therefore, the osmotic pressure of the standard solution in Comparative Example 1 is 321, and the osmotic pressure of the standard prepared solution is higher than that of breast milk and the difference is large, which does not meet the requirements of isotonic solution (isotonic solution 260-299mOsm / kg H2O). Further, such a comparison shows that even if a high content of lactose (380 parts / 1000 parts) is used in schemes such as Example 1, the molecular weight distribution of the protein of the present invention can well inhibit the increase of osmotic pressure. Compared with Example 1 and Example 3, the molecular weight distribution of Comparative Example 2 is not within the scope of the present invention, so the bitter taste can be tasted particularly severely, which is greatly different from the bitter taste of the examples. It should be noted that, although the technical solution of the present invention is introduced with specific examples, those skilled in the art will appreciate that the present invention should not be limited thereto. The embodiments of the present invention have been described above, and the above description is exemplary, not exhaustive, and is not limited to the disclosed embodiments. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the described embodiments. The selection of terms used herein is intended to best explain the principles of the embodiments, practical applications, or technical improvements in the market, or to enable other persons of ordinary skill in the art to understand the embodiments disclosed herein.

Claims

1. A whey protein composition, characterized in that The protein composition at least partially comprises degraded components of whey protein, Wherein, the protein component in the protein composition has the following molecular weight distribution: (i) the content of protein components with a molecular weight of less than 5000 Da is 80% to 96% by mass; (ii) the content of protein components with a molecular weight of 5000Da to 10000Da is 0.5% to 10% by mass; (iii) The content of protein components with a molecular weight greater than 10,000 Da is 0 to 10% by mass. The content is the content of each of the three protein components in the total protein components based on dry weight.

2. The protein composition according to claim 1, characterized in that The degradation is enzymatic degradation in the presence of an enzyme.

3. The protein composition according to claim 1 or 2, characterized in that The protein components in the protein composition are all derived from whey protein.

4. The protein composition according to any one of claims 1 to 3, characterized in that The protein composition further comprises a carbohydrate component, and optionally one or more of a fat component and a mineral salt, and the content of the carbohydrate is 30% by weight or less based on dry weight.

5. The method for preparing a protein composition according to any one of claims 1 to 4, characterized in that: The method comprises: The step of enzymatically hydrolyzing the whey protein raw material in the presence of an enzyme, The whey protein raw material is selected from one or more of concentrated whey protein and isolated whey protein.

6. The method according to claim 5, characterized in that The enzyme is selected from one or more of alkaline protease, trypsin, pepsin, acidic protease, neutral protease, protein deamidase, flavor protease, aminopeptidase and carboxypeptidase.

7. The method according to claim 5 or 6, characterized in that: The enzyme is a combination of alkaline protease and flavor protease.

8. A formula dairy product, characterized in that: The dairy products include: (A) The protein composition according to any one of claims 1 to 4, and in addition thereto one or more of the following additional components: (B) Carbohydrate components, (C) Oil components, (D) Mineral salt components, (E) Other nutritional supplement components.

9. The dairy product according to claim 8, characterized in that The (E) other nutritional supplement ingredients include one or more of vitamins, functional unsaturated fatty acids, choline, nucleotides, lutein, L-carnitine, probiotics, and inositol.

10. The dairy product according to claim 8 or 9, characterized in that The (B) carbohydrate component includes lactose, and the amount of the additional lactose added is less than 50% by mass of the total mass of the formula milk product.

11. The dairy product according to any one of claims 8 to 10, characterized in that The dairy product is an infant formula food product.

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