Emulsion simulating breast milk fat globule structure and preparation method and application thereof

Abstract

The invention discloses an emulsion simulating a breast milk fat globule structure and a preparation method and application thereof. The emulsion comprises the following raw materials in parts by weight: 3 parts of milk fat globule membrane phospholipid, 6 parts of whey protein, 4 parts of casein, 45 parts of lactose and 1 part of compound vegetable oil. The preparation method comprises the following steps: (1) preparing milk fat globule membrane phospholipid; (2) mixing with whey protein, dissolving in water, adding casein and lactose, stirring for hydration, homogenizing at high pressure, and adjusting pH; and (3) adding the compound vegetable oil, emulsifying, shearing, homogenizing at high pressure, and adjusting the pH value. The milk provided by the invention is beneficial to digestion, absorption and utilization of lipid by infants, promotes the absorption of fatty acid by the infants, also has positive help to reduce the difference between nutrition and health of infant formula milk powder and breast milk, and is suitable for research and development of infant formula milk powder.

Description

Technical Field

[0001] The invention relates to the technical field of infant formula food, and more particularly to an emulsion simulating a breast milk fat globule structure, and a preparation method and application thereof. Background Art

[0002] Human milk (HM) is the first choice for all healthy infants and young children. The fat content in HM accounts for 3%-5%, providing more than 50% of the energy required by the infant's body. It is also rich in fatty acids necessary for infant growth. The fat in HM exists in the form of milk fat globules (MFG). The MFG is wrapped by a three-layer membrane structure, the milk fat globule membrane (MFGM), which protects the MFG from being decomposed by enzymes, oxidized or aggregated. MFGM is mainly composed of milk fat globule membrane phospholipids and membrane-specific proteins (including glycoproteins), as well as cholesterol, enzymes and minerals. This complex membrane interface composition is essential for the immune function and brain development of infants. Studies have shown that infants fed with HM show more advanced neurological and cognitive development in long-term studies. However, when HM feeding is not possible for some reason, infant formula (IF) becomes the best substitute. However, IF's production processes such as homogenization, sterilization and spray drying will destroy the initial structure of MFG, causing its surface to be covered with whey protein and casein, lacking the natural MFGM structure.

[0003] The average diameter of MFG is 3-5μm, and it contains more than 200 kinds of fatty acids. Saturated fatty acids (SFA) account for the highest proportion, up to more than 50%. Palmitic acid (C16:0) and monounsaturated fatty acid oleic acid (C18:1) account for the highest proportion of total fatty acids. Among them, palmitic acid is mainly distributed in the Sn-2 position of triglycerides, while C18:1 is mainly distributed in the Sn-1,3 position. This structural feature of triglycerides (TAG) is of great significance for the development of infant intestines and lipid absorption. In addition, breast milk also contains long-chain polyunsaturated fatty acids such as arachidonic acid (ARA, C20:4), eicosapentaenoic acid (EPA, C20:5) and docosahexaenoic acid (DHA, C22:6), which play a very important role in regulating the nervous system, vision and cognitive development of newborns.

[0004] In addition, breast milk is rich in phospholipids. Polar lipids (phospholipids and sphingomyelin) are mainly present on MFGM, and the main types of polar lipids present in the membrane are phosphatidylcholine (PC), phosphatidylethanolamine (PE), phosphatidylinositol (PI), phosphatidylserine (PS) and sphingomyelin (SM). Among them, PC and SM are mainly located on the outer bilayer membrane, while PE, PS and PI are mainly concentrated on the inner surface of the membrane. SM and PC are abundant polar lipid categories in human milk. Previous studies have confirmed that SM has a protective effect on lipid metabolism disorders, intestinal microecological disorders and inflammation, and plays an important role in the normal growth and development of infants.

[0005] However, factors such as the composition, structure and lipid droplet size of the fat globule interface significantly affect infant digestion and absorption. The special structure of breast milk fat globules not only affects the short-term growth results of infants, but also has long-term benefits for their growth, development, metabolic health, etc. A previous nutrition and metabolomics study showed that the metabolic phenotype of infants fed with IF tends to be "protein metabolism", while infants fed with HM tend to be "fat metabolism". The difference between these two metabolic phenotypes is caused by insufficient fat utilization caused by IF-fed infants. Studies have confirmed that factors such as the composition of each substance on the interface, their ratio and complex interactions can significantly affect the adsorption order of substances, regulate the activity and action site of lipase, and thus affect digestibility. Therefore, research on IF is increasingly focused on simulating the composition and structure of breast milk fat globules to narrow the difference between IF feeding and HM feeding.

[0006] At present, commercially available infant formula milk powder usually adds whey protein and soy lecithin as emulsifiers to protect the MFG structure and meet the nutritional needs of infants. With the increasingly sophisticated simulation of the composition and structure of breast milk fat globule membrane, egg yolk lecithin and milk fat globule membrane phospholipids have become a new strategy to improve the structure and stability of MFG due to their unique nutritional and functional ingredients. During the preparation of infant formula milk powder, phospholipids and whey protein (WP) can interact and adsorb on the fat globule interface to form a dense protective layer. Although it can simulate the MFGM structure, the type of phospholipids, the ratio with WP, and the difference in fatty acid composition significantly affect the interaction with WP, and further have a significant impact on the interface composition, structure and digestion characteristics of fat globules in emulsions or infant formula milk powder.

[0007] In addition, the study found that the composition of each substance on the interface, the ratio between them, and the complex interactions will significantly affect the adsorption order of the substance, regulate the activity and action site of lipase, and thus affect the digestibility. Most commercially available IFs add WP and phospholipids as emulsifiers to protect the MFG structure while meeting the nutritional needs of infants. Phospholipids and proteins form a dense protective layer adsorbed at the oil-water interface with strong interactions. The interfacial structure formed by them improves the stability of the system while regulating the adsorption of lipase on the interface, thereby having a certain effect on lipid digestion. Zhu et al. (Zhu et al, 2021) confirmed the importance of adding soy lecithin to IF in their study. The study showed that adding 5% lecithin improved the stability of the system by reducing protein flocculation and greatly improved lipid digestion. Soy lecithin is mostly PC and PE. Compared with HM, it lacks SM, which has an important protective effect on lipid metabolism and intestinal ecology, which may lead to differences in physiological functions. With the in-depth study of milk polar lipids, more and more researchers are focusing on bovine milk phospholipid components that are close to the composition of breast milk MFGM. Liu et al. (Liu et al, 2023) studied the effect of adding milk fat globule membrane phospholipids on the physicochemical properties of IF and found that the addition of milk fat globule membrane phospholipids caused the molecular structure of WP to unfold and interact with the interface. The phospholipid-WP composite membrane formed in this way has better adsorption effect, which helps the formation of emulsion, thereby improving its stability and emulsification.

[0008] Therefore, studying the interaction between phospholipids and whey proteins is of great significance for the production of infant formula. Summary of the invention

[0009] In view of this, the object of the present invention is to provide a simulated breast milk fat globule structure emulsion and a preparation method and application thereof, so as to solve the deficiencies in the prior art.

[0010] In order to achieve the above object, the present invention adopts the following technical solution:

[0011] A breast milk fat globule structure-simulating emulsion comprises the following raw materials in parts by weight: 3 parts of milk fat globule membrane phospholipids, 6 parts of whey protein, 4 parts of casein, 45 parts of lactose and 1 part of compound vegetable oil.

[0012] The contents of protein (whey protein and casein), oil and carbohydrate in the emulsion of the present invention are 1.55 g / 100 mL, 3.50 g / 100 mL and 7.00 g / 100 mL respectively. The contained milk fat globule membrane phospholipids, whey protein, casein and lactose have different functions and effects in organisms.

[0013] Milk fat globule membrane phospholipids are the skeleton of biological membrane structure, which plays a role in maintaining the stability of fat globules. They are also amphiphilic molecules with hydrophobic tails and hydrophilic head groups, which greatly contribute to the emulsification ability of the membrane. PC and SM are the most abundant MFGM phospholipids. They are the source of choline, which is an important nutrient for brain cell membranes and can synthesize neurotransmitters, neurogenesis and synapse generation substances; SM metabolites have high physiological activity, which can reduce the negative effects of high-fat diet on colon inflammation and improve intestinal barrier function. In addition, xanthine oxidase (XO) in milk fat globule membrane phospholipids has antibacterial and mammary gland development-promoting effects, and mucin MUC1 can inhibit Escherichia coli and Helicobacter pylori. In particular, mucin MUC1 has been found to inhibit HIV. In addition, lactadhesin (also known as milk fat epidermal growth factor) is immunogenic; hypoxanthine dehydrogenase (XDH) is involved in the generation of reactive oxygen species, and butyricin (BTN) can affect the pathogenesis of autism.

[0014] Whey protein is mainly composed of β-lactoglobulin and α-lactalbumin with a small amount of protein hydrolyzed peptone, serum albumin and immunoglobulin. Among them, β-lactoglobulin is the main component, accounting for more than 50% of the total whey protein in milk, followed by α-lactalbumin. In emulsions, whey protein stabilizes the emulsion by adsorbing to the oil-water interface to reduce the interfacial tension, and is often used in food systems. However, the stability of emulsions prepared from proteins is affected by many factors, mainly including temperature, pH, salt ion concentration and protein concentration. β-lactoglobulin, as the most abundant whey protein, has an important influence on the behavior of whey protein products, especially its thermal denaturation and subsequent aggregation with itself and other proteins, as well as the formation of gel, which are of great significance in the dairy industry. In addition, β-lactoglobulin has important physiological functions and has the ability to bind to many hydrophobic and amphiphilic ligands, which makes it multifunctional. Due to its ability to bind fatty acids, it can stimulate lipase activity, thereby affecting lipid digestion. Whey protein has high nutritional value and possesses good foaming and emulsifying properties, able to hold water, lipids and other components, while providing textural properties that improve consumer acceptance of many food products, such as processed meats, dairy products and bakery products.

[0015] Casein, as a natural protein in milk, is soluble in acid and alkaline media. α-Casein is the main protein in mammals. In recent years, with the continuous progress of research, our understanding of the function of casein has become more and more in-depth. Immunoactive peptides in food sources usually come from casein contained in dairy products, which have multiple regulatory functions in the human immune system. In addition, researchers have found that peptides with carbohydrate chains mainly derived from the hydrolysis of κ-casein: casein glycomacropeptide (CGMP) have many physiological functions and unique nutritional properties, and can be widely used in functional foods and medicine. It is reported that CGMP has anti-inflammatory activity, such as improving inflammatory bowel disease (IBD) and immunotherapy (Zhu, Chen, 2023). β-Casein is the main protein component of breast milk, which can promote the absorption of calcium ions, phosphorus ions and other divalent cations, such as iron ions and zinc ions, and has a positive effect on improving the symptoms of calcium, iron, zinc and other element deficiencies (Chen et al, 2020).

[0016] Lactose is a disaccharide composed of galactose and glucose. After being ingested by an organism, it is usually enzymatically hydrolyzed to produce glucose and galactose. Its main physiological function is to provide energy for the body's activities. In addition, it has been reported that lactose plays an important role in the brain development of young animals and many neural regulatory functions. At the same time, lactose also plays an important role in immune regulation and has important functions such as anti-inflammatory and antibacterial (Xu et al, 2024).

[0017] Furthermore, the above-mentioned composite vegetable oil includes the following raw materials in parts by weight: 25 parts of palm oil, 25 parts of coconut oil, 15 parts of soybean oil, 15 parts of corn oil, 10 parts of rapeseed oil and 10 parts of sunflower oil.

[0018] A further beneficial effect of the above method is that the composite vegetable oil selected in the present invention is used as the emulsified oil core in the emulsion, and after compounding, the structure of the fat globules and the composition of fatty acids and glycerides in the emulsion can be made closer to breast milk.

[0019] A method for preparing the above-mentioned simulated breast milk fat globule structure emulsion specifically comprises the following steps:

[0020] (1) dissolving buttermilk powder in water, stirring and hydrating, dissociating, centrifuging, collecting supernatant, adding organic reagent and mixing, centrifuging again, collecting supernatant, filtering, centrifuging for the third time, collecting supernatant, evaporating to dryness, dissolving in cold acetone, collecting precipitate, dissolving in chloroform, and drying to obtain milk fat globule membrane phospholipids;

[0021] (2) mixing milk fat globule membrane phospholipids and whey protein and dissolving them in water, adding casein and lactose, stirring and hydrating, high pressure homogenizing, and adjusting the pH to obtain a phospholipid-protein complex solution;

[0022] (3) heating the composite vegetable oil in a water bath, adding it to the phospholipid-protein composite solution, emulsifying and shearing, high pressure homogenizing, and adjusting the pH to obtain an emulsion with a simulated breast milk fat globule structure;

[0023] Furthermore, in the above step (1), the concentration of buttermilk powder is 50 mg / mL; the stirring and hydrating temperature is 25°C, the speed is 1000 rpm / min, and the time is 1 hour; the dissociation reagent is sodium citrate, and the concentration is 20 mg / mL; the centrifugal force of the centrifugation is 4750×g, the number of times is 2 times, each time for 20 minutes; the organic reagent is a mixed solution of chloroform and methanol, the volume ratio is 2:1, and the amount is 4 times the volume of the supernatant; the centrifugal force of the second centrifugation is 4750×g, and the time is 10 minutes; the pore size of the filtration membrane is 0.45μm; the centrifugal force of the third centrifugation is 7100×g, and the time is 10 minutes; the temperature of evaporation and drying is 60°C.

[0024] Furthermore, in the above step (2), the stirring hydration temperature is 25°C, the speed is 1000 rpm / min, and the time is 1 hour; the pressure of the high-pressure homogenization is 0-80 MPa, and the cycle is 1-5 times; the pH is adjusted to 6.8, and the reagent is 1M NaOH.

[0025] Furthermore, in the above step (3), the water bath heating temperature is 50°C for 5 min; the emulsification shearing speed is 10000 rpm / min for 5 min; the high pressure homogenization pressure is 0-20 MPa, and the cycle is 1-5 times; the pH is adjusted to 6.8, and the reagent is 1 M NaOH.

[0026] The present invention also seeks to protect the use of the simulated breast milk fat globule structure emulsion or the simulated breast milk fat globule structure emulsion prepared by the above preparation method in the preparation of infant formula milk powder.

[0027] It can be seen from the above technical solution that compared with the prior art, the beneficial effects of the present invention are as follows:

[0028] 1. The present invention discloses an emulsion containing a composition of milk fat globule membrane phospholipids and whey protein in a special ratio to simulate the structure of breast milk fat globules. The emulsion is prepared by determining the optimal compounding ratio of milk fat globule membrane phospholipids and whey protein, adding casein and lactose, and using a composite vegetable oil as an oil core through emulsification shearing and high-pressure homogenization. The emulsion can achieve maximum simulation of breast milk fatty acids, fat globule particle size and fat globule interface composition, so as to achieve in-depth breast milkization of infant formula milk powder and improve the situation of insufficient fat utilization in infant formula milk powder feeding, and has high practical use value.

[0029] 2. The present invention introduces a special ratio of milk fat globule membrane phospholipids and whey protein into the emulsion, making the product system more evenly distributed, not only achieving breast milking to the greatest extent in terms of fat composition, fat globule particle size and fat globule interface composition, but also having better lipolysis ability in the process of simulated digestion, thereby achieving a more comprehensive simulation of breast milk fat level, which can be used to improve the situation of insufficient fat utilization in infants fed with infant formula milk powder. In addition, the content ratio of each component of the emulsion of the present invention is also very close to that of breast milk.

[0030] 3. Based on previous research, the present invention found that when the mass ratio of milk fat globule membrane phospholipids to whey protein is 5:10, the prepared simulated breast milk fat globule structure emulsion has high fatty acid saturation and high sphingomyelin content, which makes the fatty acids exhibit different properties, and has higher stability and emulsification.

[0031] 4. The present invention starts from three aspects: fatty acid composition, fat globule size and fat globule interface composition, and simulates the fat composition and structure of breast milk in a more detailed manner. In addition, it is found that adding milk fat globule membrane phospholipids in this ratio has a positive effect on the in vitro digestion of the emulsion, which not only shows that the emulsion of the present invention is beneficial to the digestion, absorption and utilization of lipids by infants, and promotes the absorption of fatty acids by infants, but also has a positive help in narrowing the nutritional and health gap between infant formula milk powder and breast milk, and is suitable for the research and development of infant formula milk powder.

[0032] 5. The present invention uses breast milk as a reference object, and adds a special ratio of milk fat globule membrane phospholipid-whey protein complex and mixed vegetable oils to simulate breast milk fat in terms of fatty acid composition, fat globule particle size and fat globule interface composition. The present invention can provide a technical reference for the production process of breast milk infant formula milk powder. At the same time, the emulsion of the present invention can improve the situation of insufficient fat utilization of infants fed with infant formula milk powder, and can also promote the brain and nerve development of newborns, improve cognitive ability and anti-infection ability, so that the digestion behavior of the added emulsion is closer to breast milk. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 It is a comparison chart of the in vitro digestion particle size distribution of breast milk, the emulsion of Example 1 and two commercially available infant formula milk powders, wherein G0, G30, G60, I60 and I120 respectively represent before in vitro digestion, 30min and 60min of gastric digestion, and 60min and 120min of intestinal digestion;

[0034] Figure 2 The figure is a comparison diagram of the triglyceride and protein structure distribution of in vitro digestion of breast milk, the emulsion of Example 1 and two commercially available infant formula milk powders, wherein triglycerides are marked in green and proteins are marked in red;

[0035] Figure 3 This is a comparison diagram of the in vitro digestion phospholipid structure distribution of breast milk, the emulsion of Example 1, and two commercially available infant formula milk powders, wherein phospholipids are marked in red;

[0036] Figure 4 The in vitro digestion and lipolysis diagrams of breast milk, the emulsion of Example 1 and two commercially available infant formula milk powders. DETAILED DESCRIPTION

[0037] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0038] Example 1

[0039] A simulated breast milk fat globule structure emulsion, comprising the following raw materials by weight: 3 kg of milk fat globule membrane phospholipids, 6 kg of whey protein, 4 kg of casein, 45 kg of lactose and 1 kg of compound vegetable oil;

[0040] The composite vegetable oil includes the following raw materials by weight: 250 g of palm oil, 250 g of coconut oil, 150 g of soybean oil, 150 g of corn oil, 100 g of rapeseed oil and 100 g of sunflower oil;

[0041] The method for preparing the simulated breast milk fat globule structure emulsion specifically comprises the following steps:

[0042] (1) Dissolve 50 mg / mL buttermilk powder in water, stir and hydrate at 25°C at a speed of 1000 rpm / min for 1 hour, add 20 mg / mL sodium citrate for dissociation, refrigerate at 4°C overnight, centrifuge twice at a centrifugal force of 4750×g for 20 minutes each time, collect the supernatant, add 4 times the volume of a mixed solution of chloroform and methanol in a volume ratio of 2:1, mix, centrifuge at a centrifugal force of 4750×g for 10 minutes, collect the supernatant, filter with a 0.45 μm membrane, centrifuge at a centrifugal force of 7100×g for 10 minutes, collect the supernatant, evaporate to dryness at 60°C, dissolve in cold acetone, collect the precipitate, dissolve in chloroform, and dry to obtain milk fat globule membrane phospholipids;

[0043] (2) mixing milk fat globule membrane phospholipids and whey protein and dissolving them in water, adding casein and lactose, stirring and hydrating at 25° C. at a speed of 1000 rpm / min for 1 h, high-pressure homogenizing at 80 MPa for 2 times, adding 1 M NaOH to adjust the pH to 6.8, and obtaining a phospholipid-protein complex solution;

[0044] (3) The composite vegetable oil was heated in a 50°C water bath for 5 min, added to the phospholipid-protein composite solution, emulsified and sheared at a speed of 10,000 rpm / min for 5 min, and high-pressure homogenized twice at 20 MPa. 1 M NaOH was added to adjust the pH to 6.8 to obtain an emulsion with a simulated breast milk fat globule structure.

[0045] Example 2

[0046] A simulated breast milk fat globule structure emulsion, comprising the following raw materials by weight: 3 kg of milk fat globule membrane phospholipids, 6 kg of whey protein, 4 kg of casein, 45 kg of lactose and 1 kg of compound vegetable oil;

[0047] The composite vegetable oil includes the following raw materials by weight: 250 g of palm oil, 250 g of coconut oil, 150 g of soybean oil, 150 g of corn oil, 100 g of rapeseed oil and 100 g of sunflower oil;

[0048] The method for preparing the simulated breast milk fat globule structure emulsion specifically comprises the following steps:

[0049] (1) Dissolve 50 mg / mL buttermilk powder in water, stir and hydrate at 25°C at a speed of 1000 rpm / min for 1 hour, add 20 mg / mL sodium citrate for dissociation, refrigerate at 4°C overnight, centrifuge twice at a centrifugal force of 4750×g for 20 minutes each time, collect the supernatant, add 4 times the volume of a mixed solution of chloroform and methanol in a volume ratio of 2:1, mix, centrifuge at a centrifugal force of 4750×g for 10 minutes, collect the supernatant, filter with a 0.45 μm membrane, centrifuge at a centrifugal force of 7100×g for 10 minutes, collect the supernatant, evaporate to dryness at 60°C, dissolve in cold acetone, collect the precipitate, dissolve in chloroform, and dry to obtain milk fat globule membrane phospholipids;

[0050] (2) mixing milk fat globule membrane phospholipids and whey protein and dissolving them in water, adding casein and lactose, stirring and hydrating at 25° C. at a speed of 1000 rpm / min for 1 h, high-pressure homogenizing at 60 MPa for 5 times, adding 1 M NaOH to adjust the pH to 6.8, and obtaining a phospholipid-protein complex solution;

[0051] (3) The composite vegetable oil was heated in a water bath at 50°C for 5 min, added to the phospholipid-protein composite solution, emulsified and sheared at a speed of 10,000 rpm / min for 5 min, high-pressure homogenized at 10 MPa for 5 times, and 1 M NaOH was added to adjust the pH to 6.8 to obtain an emulsion with a simulated breast milk fat globule structure;

[0052] Example 3

[0053] A simulated breast milk fat globule structure emulsion, comprising the following raw materials by weight: 3 kg of milk fat globule membrane phospholipids, 6 kg of whey protein, 4 kg of casein, 45 kg of lactose and 1 kg of compound vegetable oil;

[0054] The composite vegetable oil includes the following raw materials by weight: 250 g of palm oil, 250 g of coconut oil, 150 g of soybean oil, 150 g of corn oil, 100 g of rapeseed oil and 100 g of sunflower oil;

[0055] The method for preparing the simulated breast milk fat globule structure emulsion specifically comprises the following steps:

[0056] (1) Dissolve 50 mg / mL buttermilk powder in water, stir and hydrate at 25°C at a speed of 1000 rpm / min for 1 hour, add 20 mg / mL sodium citrate for dissociation, refrigerate at 4°C overnight, centrifuge twice at a centrifugal force of 4750×g for 20 minutes each time, collect the supernatant, add 4 times the volume of a mixed solution of chloroform and methanol in a volume ratio of 2:1, mix, centrifuge at a centrifugal force of 4750×g for 10 minutes, collect the supernatant, filter with a 0.45 μm membrane, centrifuge at a centrifugal force of 7100×g for 10 minutes, collect the supernatant, evaporate to dryness at 60°C, dissolve in cold acetone, collect the precipitate, dissolve in chloroform, and dry to obtain milk fat globule membrane phospholipids;

[0057] (2) mixing milk fat globule membrane phospholipids and whey protein and dissolving them in water, adding casein and lactose, stirring and hydrating at 25° C. at a speed of 1000 rpm / min for 1 h, high-pressure homogenizing once at 80 MPa, adding 1 M NaOH to adjust the pH to 6.8, and obtaining a phospholipid-protein complex solution;

[0058] (3) The composite vegetable oil was heated in a water bath at 50°C for 5 min, added to the phospholipid-protein composite solution, emulsified and sheared at a speed of 10,000 rpm / min for 5 min, high-pressure homogenized once at 20 MPa, and 1 M NaOH was added to adjust the pH to 6.8 to obtain an emulsion with a simulated breast milk fat globule structure;

[0059] Performance Testing

[0060] 1. Screening of the ratio of milk fat globule membrane phospholipids and whey protein

[0061] On the basis of Example 1, different simulated breast milk fat globule structure emulsions were prepared by changing the types of phospholipids and the ratio of phospholipids to whey protein, and the average particle sizes of the emulsions were measured respectively.

[0062] The results are shown in Table 1.

[0063] Table 1 Average particle size of emulsions prepared from different ratios of milk fat globule membrane phospholipids and whey protein

[0064]

[0065] As shown in Table 1, under the condition of adding different proportions of phospholipids, the emulsions showed different fat globule particle sizes. Just after the addition of phospholipids (i.e., the ratio of phospholipids to whey protein was 2:10), the particle size of all emulsions was significantly reduced compared with whey protein (P<0.05). Subsequently, the emulsion system formed a larger phospholipid-whey protein complex due to the continuous addition of phospholipids, which made the particle size gradually increase. In the emulsion stabilized by milk fat globule membrane phospholipids-whey protein, when the ratio of milk fat globule membrane phospholipids to whey protein was 5:10, its particle size distribution was relatively stable and the particle size was small, indicating that the lipid droplets in the emulsion under this condition were more evenly distributed. Therefore, the milk fat globule membrane phospholipids-whey protein with a ratio of 5:10 was selected as the optimal addition parameter.

[0066] 2. Determination of particle size, structure and lipolysis during in vitro digestion

[0067] Breast milk, the simulated breast milk fat globule structure emulsion prepared in Example 1, and two commercially available infant formula milk powders were taken to measure the particle size, structure, and lipolysis degree of the emulsions during in vitro digestion.

[0068] The results are shown in Table 2 and Figure 1-4 shown.

[0069] Table 2 Particle size of different emulsions during in vitro digestion

[0070] Digestion stage G0 G30 G60 I60 I120 Breast milk (μm) <![CDATA[4.24±0.31 a ]]> <![CDATA[9.21±0.97 d ]]> <![CDATA[13.93±0.58 d ]]> <![CDATA[29.03±1.22 a ]]> <![CDATA[13.88±1.01 a ]]> Example 1 (μm) <![CDATA[3.28±0.24 b ]]> <![CDATA[11.78±0.29 c ]]> <![CDATA[20.87±1.50 c ]]> <![CDATA[26.64±1.67 b ]]> <![CDATA[11.40±1.13 b ]]> Commercially available IF1(μm) <![CDATA[0.35±0.01 c ]]> <![CDATA[14.75±0.87 b ]]> <![CDATA[25.62±1.80 b ]]> <![CDATA[9.17±1.04 d ]]> <![CDATA[5.12±0.28 d ]]> Commercially available IF2(μm) <![CDATA[0.39±0.01 c ]]> <![CDATA[22.98±0.70 a ]]> <![CDATA[33.79±2.62 a ]]> <![CDATA[15.00±0.19 c ]]> <![CDATA[8.80±0.99 c ]]>

[0071] From Table 2 and Figure 1-4 It can be seen that before gastric digestion, breast milk presents a multimodal distribution, with peak values ​​of 1.17 μm, 4.38 μm and 39.6 μm, respectively. Its average particle size D4,3 is 4.24 ± 0.31 μm, which is significantly higher than that of the emulsion in Example 1 (P < 0.05). The particle sizes of commercially available IF1 and IF2 are both nanometers, 350 nm and 390 nm, respectively, which is consistent with previous research results. In the emulsion before digestion, the particle sizes of IF1 and IF2 both present a narrow unimodal distribution (e.g. Figure 1 This indicates that the system has high stability.

[0072] Before in vitro digestion, it can be clearly observed that breast milk and the emulsion of Example 1 have complete fat globule structures, with protein wrapping at their interfaces, and a large number of phospholipid rings are found to be present and evenly distributed (e.g. Figure 2-3As shown). After the gastric digestion stage, the dense protective layer formed by the interaction of protein-phospholipid at the fat globule interface of the emulsion of Example 1 well protects its original structure until the intestinal digestion stage, delays its lipid digestion, and its microstructural changes are similar to those of breast milk, indicating that the protein-phospholipid affects through interaction. After entering the intestinal digestion stage, the interaction between MFGM phospholipids and proteins in breast milk and the emulsion of Example 1 weakens, and the composite membrane is gradually destroyed under the action of lipase and protease, and triglycerides are released and dispersed in the emulsion. The protective layer formed after the addition of MFGM phospholipids in the emulsion of Example 1 well protects the structure of the fat globules, thereby keeping the system in a relatively stable state.

[0073] At the same time, the emulsion of Example 1 has good lipolysis ability (such as Figure 4 As shown in the figure, after entering the intestinal digestion stage, the fat decomposition rate of breast milk and the emulsion of Example 1 is much higher than that of IF1 and IF2. Among them, the lipolysis degree of the emulsion of Example 1 reaches 81.46±0.75%, which is slightly lower than breast milk (85.49±1.89%). It can be seen that the addition of an appropriate proportion of milk fat globule membrane phospholipids (containing a high SM content) can protect the initial intact structure of the milk fat globule, making its digestion behavior closer to that of breast milk.

[0074] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A simulated breast milk fat globule structure emulsion, characterized in that: The invention comprises the following raw materials in parts by weight: 3 parts of milk fat globule membrane phospholipids, 6 parts of whey protein, 4 parts of casein, 45 parts of lactose and 1 part of compound vegetable oil.

2. The simulated breast milk fat globule structure emulsion according to claim 1, characterized in that: The composite vegetable oil comprises the following raw materials in parts by weight: 25 parts of palm oil, 25 parts of coconut oil, 15 parts of soybean oil, 15 parts of corn oil, 10 parts of rapeseed oil and 10 parts of sunflower oil.

3. A method for preparing the simulated breast milk fat globule structure emulsion according to claim 1, characterized in that: The specific steps include: (1) dissolving buttermilk powder in water, stirring and hydrating, dissociating, centrifuging, collecting supernatant, adding organic reagent and mixing, centrifuging again, collecting supernatant, filtering, centrifuging for the third time, collecting supernatant, evaporating to dryness, dissolving in cold acetone, collecting precipitate, dissolving in chloroform, and drying to obtain milk fat globule membrane phospholipids; (2) mixing milk fat globule membrane phospholipids and whey protein and dissolving them in water, adding casein and lactose, stirring and hydrating, high pressure homogenizing, and adjusting the pH to obtain a phospholipid-protein complex solution; (3) heating the composite vegetable oil in a water bath, adding it to the phospholipid-protein composite solution, emulsifying and shearing, high pressure homogenizing, and adjusting the pH to obtain the simulated breast milk fat globule structure emulsion.

4. The method for preparing a simulated breast milk fat globule structure emulsion according to claim 3, characterized in that: In step (1), the concentration of the buttermilk powder is 50 mg / mL; the temperature of the stirring hydration is 25° C., the speed is 1000 rpm / min, and the time is 1 h; and the dissociation reagent is sodium citrate with a concentration of 20 mg / mL.

5. The method for preparing a simulated breast milk fat globule structure emulsion according to claim 3, characterized in that: In step (1), the centrifugal force of the centrifugation is 4750×g, the number of times is 2 times, each time is 20 minutes; the organic reagent is a mixed solution of chloroform and methanol, the volume ratio is 2:1, and the amount is 4 times the volume of the supernatant; the centrifugal force of the second centrifugation is 4750×g, and the time is 10 minutes; the pore size of the filtration membrane is 0.45μm; the centrifugal force of the third centrifugation is 7100×g, and the time is 10 minutes; the temperature of the evaporation and drying is 60°C.

6. The method for preparing a simulated breast milk fat globule structure emulsion according to claim 3, characterized in that: In step (2), the stirring hydration temperature is 25° C., the speed is 1000 rpm / min, and the time is 1 h.

7. The method for preparing a simulated breast milk fat globule structure emulsion according to claim 3, characterized in that: In step (2), the pressure of the high-pressure homogenization is 0-80 MPa, and the cycle is 1-5 times; the pH is adjusted to 6.8, and the reagent is 1M NaOH.

8. The method for preparing a simulated breast milk fat globule structure emulsion according to claim 3, characterized in that: In step (3), the water bath heating temperature is 50° C. and the heating time is 5 min.

9. The method for preparing a simulated breast milk fat globule structure emulsion according to claim 3, characterized in that: In step (3), the speed of the emulsification shearing is 10000 rpm / min, and the time is 5 min; the pressure of the high-pressure homogenization is 0-20 MPa, and the cycle is 1-5 times; the pH is adjusted to 6.8, and the reagent is 1 M NaOH.

10. Use of the simulated breast milk fat globule structure emulsion according to claim 1 or 2 or the simulated breast milk fat globule structure emulsion prepared by the preparation method according to any one of claims 3 to 9 in preparing infant formula milk powder.

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