Infant nutritional composition

Abstract

To provide a nutritive composition for infants having an amino acid composition more similar to breast milk, making it possible to ensure sufficient amino acid nutrition without excessive ingestion of protein.SOLUTION: The present disclosure provides a nutritive composition for infants containing protein. In the composition, the total content of phenylalanine and tyrosine is 7.6 wt.% or more in terms of total amino acid content, and 90 wt.% or more of the total protein content is derived from milk.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to nutritional compositions for infants. [Background technology]

[0002] Human milk (breast milk) is the ideal nutrition for human infants. However, if breast milk cannot be given for some reason, nutritional compositions such as formula powder or liquid formula are commonly used as substitutes for breast milk. Such nutritional compositions are made primarily from cow's milk, and the nutritional components are adjusted to make the composition closer to that of breast milk. In particular, certain legal standards have been established for infant formula (Non-Patent Document 1).

[0003] Infant nutritional compositions typically contain protein, an essential nutrient for infants. In general, when manufacturing infant nutritional compositions, casein and whey protein derived from cow's milk are used as protein sources. In nutritional compositions such as infant formula, there is a demand for their composition to be closer to that of breast milk in order to further improve the health and development of infants. The ratio of casein to whey protein in cow's milk is 8:2 (weight ratio), while the ratio in breast milk is 4:6 (weight ratio). Therefore, when manufacturing infant nutritional compositions, the ratio of casein to whey protein is designed to be closer to that of breast milk.

[0004] The nutritional value of protein varies depending on the amino acids that make it up. Furthermore, essential amino acids, which humans cannot synthesize, must be ingested through diet, but the amount required by infants varies for each essential amino acid. It has been pointed out that infant nutritional compositions made using cow's milk-derived casein and whey protein may contain amino acids necessary for infants that are insufficient compared to breast milk, depending on the type of amino acid. This is because, even if breast milk and cow's milk contain the same fractions called casein and whey protein, the protein compositions that make up each fraction are different, and the amino acid composition of each fraction also differs between breast milk and cow's milk. Therefore, it has been proposed to adjust the amino acid composition by adding crystalline amino acids or removing some proteins from the whey protein fraction in cow's milk (Patent Documents 1 to 3). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 8-214775 [Patent Document 2] Special Publication No. 2011-504365 [Patent Document 3] Special Publication No. 2014-520549 [Non-patent literature]

[0006] [Non-Patent Document 1] Ingestion Table No. 296 (September 9, 2019) Attachment 1 Criteria for labeling permission for foods for special dietary uses Summary of the Invention [Problem to be solved by the invention]

[0007] In addition to the differences in amino acid composition between cow's milk protein and breast milk protein, their bioavailability is thought to differ, so when infant nutritional compositions are made using cow's milk protein, a larger amount of protein has been added than in breast milk. However, excessive intake of protein or certain amino acids during infancy has been shown to have adverse effects, such as burdening infants' digestion and metabolism. However, simply reducing the protein content in infant nutritional compositions may result in a deviation from the composition of breast milk, raising concerns that infants may not receive the amino acid nutrients they need. In this situation, the present invention aims to provide a nutritional composition for infants that has an amino acid composition closer to that of breast milk, ensuring sufficient amino acid nutrition without excessive protein intake. [Means for solving the problem]

[0008] As a result of extensive research aimed at solving the above-mentioned problems, the present inventors have found that, among the essential amino acids contained in conventional infant nutritional compositions, phenylalanine and tyrosine tend to be most deficient compared to the composition of breast milk. As shown in Table 1, in 2007, a WHO committee established the age-specific essential amino acid requirements and presented the amino acid composition of breast milk (WHO / FAO / UNU (2007), WHO technical report series no. 935). In the amino acid composition of breast milk shown here, the combined content of phenylalanine and tyrosine relative to the total amino acids was 9.7% by weight, whereas in conventional infant formula, the combined content was as low as 7.2-7.5% by weight. Based on this analysis, the inventors came up with the idea of ​​increasing the content of phenylalanine and tyrosine in the amino acid composition of infant nutritional compositions. Taking note of the differences in the amino acid composition ratios of casein and whey protein, which are milk-derived proteins, and the high bioavailability of casein, they came up with the idea that by adjusting the blending ratios in the composition, it would be possible to increase the content of phenylalanine and tyrosine while reducing excess amino acids, thereby ensuring sufficient amino acid nutrition and achieving an amino acid composition closer to that of breast milk, and thus completed the present invention.

[0009] [Table 1]

[0010] That is, the present invention is a nutritional composition for infants containing protein, in which the total content of phenylalanine and tyrosine per total amino acid is 7.6% by weight or more, and 90% by weight or more of the total protein is derived from milk. In a preferred embodiment of the present invention, 33 to 70% by weight of the total protein is casein. In a preferred embodiment of the present invention, the content of tyrosine relative to the total amino acids is 3.6% by weight or more. In a preferred embodiment of the present invention, the phenylalanine content relative to the total amino acids is 3.8% by weight or more. In a preferred embodiment of the present invention, the total protein content is less than 2.15 g per 100 kcal of the composition. In a preferred embodiment of the present invention, the ratio of the content of tryptophan to the total content of phenylalanine and tyrosine is 21% by weight or less. In a preferred embodiment of the present invention, the nutritional composition is a formula. In this specification, when a numerical range is indicated with "to", both ends of the range are included. For example, 33 to 70% by weight means 33% by weight or more and 70% by weight or less. [Effects of the Invention]

[0011] According to the present invention, there is provided a nutritional composition for infants that can ensure sufficient amino acid nutrition and has an amino acid composition closer to that of breast milk. The formula ensures sufficient amounts of phenylalanine and tyrosine, which tend to be deficient compared to breast milk. In addition, the formula provides an appropriate amount of threonine, which tends to be contained in excess compared to breast milk in conventional infant formulas. The present invention also makes it possible to reduce the total amount of protein contained in the composition, thereby realizing a nutritional composition that is more useful for the health and development of infants. [Brief explanation of the drawings]

[0012] [Figure 1] Electrophoresis images showing the casein content in formulas 1-3. DETAILED DESCRIPTION OF THE INVENTION

[0013] The present invention will now be described in detail. However, the present invention is not limited to the following embodiments and can be freely modified within the scope of the present invention.

[0014] The infant nutritional compositions of the present invention contain protein. At least 90% by weight of the total protein in the infant nutritional composition is milk-derived, preferably at least 95% by weight, more preferably at least 98% by weight is milk-derived protein. Here, total protein refers to the total amount of protein, calculated by multiplying the nitrogen content of a nutritional composition by the nitrogen-to-protein conversion factor of 6.25. The nitrogen content can be quantified, for example, based on the "Food Labeling Standards (March 30, 2015, Shoshoku No. 139)" (Annex: Analytical Methods for Nutritional Components, etc.) (hereinafter referred to as "Analytical Methods in the Food Labeling Standards"), i.e., using the Kjeldahl method or a combustion method including the modified Dumas method.

[0015] The composition of the present invention typically contains whey protein as a milk-derived protein. The whey protein may be a highly purified whey protein, or a low-purity whey protein containing components other than whey protein. The milk raw material used to produce the whey protein raw material can also be used as a substitute for whey protein. In this case, the milk raw material can be called the whey protein raw material. As the whey protein raw material, ordinary dairy products containing whey protein, such as raw milk, skim milk, whole milk powder, and skim milk powder, can be used.

[0016] Whey protein can be purified by adding rennet, inorganic acids, or organic acids to milk or skim milk powder to remove casein and milk fat, or by further treating the whey from the above process, or milk or skim milk, with methods such as gel filtration, ultrafiltration, or ion exchange. Whey protein concentrates, whey protein isolates, etc. obtained by these methods can be used. Commercially available whey protein concentrates (WPCs), whey protein isolates (WPIs), and other whey protein raw materials can also be used.

[0017] Generally, whey proteins include β-lactoglobulin, α-lactalbumin, serum albumin, immunoglobulin, lactoferrin, proteose peptone, etc., and the whey proteins referred to herein may also contain these components. The whey protein raw material used as the whey protein may be one type only, or two or more types may be mixed and used.

[0018] The composition of the present invention typically contains a milk-derived protein other than the whey protein. Such proteins may be any protein commonly used in orally ingested compositions, such as skim milk powder, whole milk powder, casein, or soy protein. Casein is further classified into α-casein, β-casein, κ-casein, etc., and in the present invention, casein refers to the sum of all these caseins. Furthermore, the casein used in the present invention may have a β-casein content equivalent to that of cow's milk (approximately 38%).

[0019] The protein in the present invention may include the above-mentioned milk-derived proteins and peptide / amino acid fractions obtained by hydrolysis of other proteins. Free amino acids may also be used as a protein source in the nutritional composition.

[0020] In the composition of the present invention, the casein protein content of the total protein is usually 33% by weight or more, preferably 41% by weight or more, and more preferably 44% by weight or more. The upper limit of the casein protein content of the total protein is usually 70% by weight or less, preferably 60% by weight or less, and more preferably 59% by weight or less. That is, the casein protein content of the total protein can be 33 to 70% by weight, 33 to 60% by weight, 33 to 59% by weight, 41 to 70% by weight, 41 to 60% by weight, 41 to 59% by weight, 44 to 70% by weight, 44 to 60% by weight, or 44 to 59% by weight. As mentioned above, the majority of the milk proteins typically contained in the compositions of the present invention are casein and whey protein, and by using this proportion of casein protein, it becomes easier to achieve the phenylalanine and tyrosine contents in the infant nutritional composition described below within the specified ranges, due to the fact that casein contains large amounts of phenylalanine and tyrosine and is highly bioavailable.

[0021] The casein content of a nutritional composition can be quantified, for example, by SDS-PAGE, in which equal volumes of the nutritional composition and casein standards at various concentrations are applied to the same polyacrylamide gel, electrophoresed, and the gel is stained with Coomassie blue, and the band intensities (thickness) are compared using analytical software.

[0022] In the composition of the present invention, the total content of phenylalanine and tyrosine per total amino acid is 7.6% by weight or more, preferably 7.7% by weight or more, and more preferably 7.8% by weight or more. The upper limit of the total content of phenylalanine and tyrosine per total amino acid is usually 12% by weight or less, preferably 10% by weight or less, and more preferably 9.8% by weight or less. For example, the total content of phenylalanine and tyrosine per total amino acid can be 7.6 to 12% by weight, 7.6 to 10% by weight, 7.6 to 9.8% by weight, 7.7 to 12% by weight, 7.7 to 10% by weight, 7.7 to 9.8% by weight, 7.8 to 12% by weight, 7.8 to 10% by weight, or 7.8 to 9.8% by weight. By adjusting the content in this range, the amino acid composition of the nutritional composition becomes closer to that of breast milk. Furthermore, in the composition of the present invention, the total content of phenylalanine and tyrosine per 100 kcal of the composition is usually 0.15 g or more, preferably 0.16 g or more. The upper limit is usually 0.22 g or less, preferably 0.19 g or less. For example, the total content of phenylalanine and tyrosine per 100 kcal of the composition can be 0.15 to 0.22 g, 0.15 to 0.19 g, 0.16 to 0.22 g, or 0.16 to 0.19 g.

[0023] Here, total amino acids generally refers to the total amount of amino acids that make up the proteins contained in the nutritional composition, namely, histidine, isoleucine, leucine, lysine, phenylalanine, tyrosine, threonine, valine, aspartic acid, asparagine, serine, glutamic acid, glutamine, glycine, alanine, arginine, proline, methionine, cysteine, and tryptophan. However, if the composition contains amino acids added in a form other than protein, such as free amino acids or peptides, the amount includes the amino acids that make up these amino acids.

[0024] The content of these amino acids can be quantified, for example, by subjecting the nutritional composition hydrolyzed with an acid or base to a high-speed amino acid analyzer or high-performance liquid chromatography. Note that glutamine and asparagine are converted to glutamic acid and aspartic acid, respectively, during hydrolysis, so glutamic acid is the sum of glutamine and glutamic acid, and aspartic acid is It is quantified as the sum of asparagine and aspartic acid. The content of a given amino acid per total amino acid refers to the ratio calculated by dividing the content of the given amino acid determined by the above method by the content of the total amino acids.

[0025] In the composition of the present invention, the tyrosine content per total amino acids is usually 3.6% by weight or more, preferably 3.7% by weight or more, and more preferably 3.8% by weight or more. The upper limit of the tyrosine content per total amino acids is usually 10% by weight or less, preferably 8% by weight or less, and more preferably 6% by weight or less. For example, the tyrosine content per total amino acids can be 3.6 to 10% by weight, 3.6 to 8% by weight, 3.6 to 6% by weight, 3.7 to 10% by weight, 3.7 to 8% by weight, 3.7 to 6% by weight, 3.8 to 10% by weight, 3.8 to 8% by weight, or 3.8 to 6% by weight. Furthermore, in the composition of the present invention, the tyrosine content per 100 kcal of the composition is usually 0.05 g or more, preferably 0.07 g or more. The upper limit is usually 0.18 g or less, preferably 0.15 g or less, and more preferably 0.095 g or less. For example, the tyrosine content per 100 kcal of the composition can be 0.05 to 0.18 g, 0.05 to 0.15 g, 0.05 to 0.095 g, 0.07 to 0.18 g, 0.07 to 0.15 g, or 0.07 to 0.095 g.

[0026] In the composition of the present invention, the phenylalanine content per total amino acids is usually 3.8% by weight or more, preferably 3.9% by weight or more, and more preferably 4% by weight or more. The upper limit of the phenylalanine content per total amino acids is usually 6% by weight or less, preferably 5% by weight or less, and more preferably 4.4% by weight or less. For example, the phenylalanine content per total amino acids can be 3.8 to 6% by weight, 3.8 to 5% by weight, 3.8 to 4.4% by weight, 3.9 to 6% by weight, 3.9 to 5% by weight, 3.9 to 4.4% by weight, 4 to 6% by weight, 4 to 5% by weight, or 4 to 4.4% by weight. Furthermore, in the composition of the present invention, the phenylalanine content per 100 kcal of the composition is usually 0.05 g or more, preferably 0.07 g or more. The upper limit is usually 0.15 g or less, preferably 0.12 g or less. For example, the tyrosine content per 100 kcal of the composition can be 0.05 to 0.15 g, 0.05 to 0.12 g, 0.07 to 0.15 g, or 0.07 to 0.12 g.

[0027] In the composition of the present invention, the ratio of the tryptophan content to the total content of phenylalanine and tyrosine is 22% by weight or less, preferably 21% by weight or less, and more preferably 20% by weight or less. The lower limit of the ratio of the tryptophan content to the total content of phenylalanine and tyrosine is usually 14% by weight or more, preferably 15% by weight or more, and more preferably 17% by weight or more. For example, the ratio of the tryptophan content to the total content of phenylalanine and tyrosine can be 14 to 22% by weight, 14 to 21% by weight, 14 to 20% by weight, 15 to 22% by weight, 15 to 21% by weight, 15 to 20% by weight, 17 to 22% by weight, 17 to 21% by weight, or 17 to 20% by weight.

[0028] In the composition of the present invention, the histidine content per total amino acids is usually 2.8% by weight or less, preferably 2.6% by weight or less, and more preferably 2.4% by weight or less. The lower limit of the histidine content per total amino acids is usually 1.5% by weight or more, preferably 1.8% by weight or more, and more preferably 2% by weight or more. For example, the histidine content per total amino acids can be 1.5 to 2.8% by weight, 1.5 to 2.6% by weight, 1.5 to 2.4% by weight, 1.8 to 2.8% by weight, 1.8 to 2.6% by weight, 1.8 to 2.4% by weight, 2 to 2.8% by weight, 2 to 2.6% by weight, or 2 to 2.4% by weight. In the composition of the present invention, the content of cysteine ​​per total amino acid is usually 2.2%. The cysteine ​​content per total amino acids is usually 1.0% or more, preferably 1.2% or more, and more preferably 1.4% or more. For example, the cysteine ​​content per total amino acids can be 1 to 2.2% by weight, 1 to 2% by weight, 1 to 1.7% by weight, 1.2 to 2.2% by weight, 1.2 to 2% by weight, 1.2 to 1.7% by weight, 1.4 to 2.2% by weight, 1.4 to 2% by weight, or 1.4 to 1.7% by weight.

[0029] The nutritional composition of the present invention, which has such a composition, is close to the amino acid composition of breast milk and is sufficiently digested, absorbed, and utilized in the body by infants who ingest it, so even if the total protein content contained in the composition is reduced compared to conventional compositions, sufficient amino acid nutrition is ensured.

[0030] That is, the total protein content of the composition of the present invention may be less than 2.15 g per 100 kcal of composition, more preferably 2.05 g or less, and even more preferably 1.95 g or less. The lower limit of the total protein content is typically 1.5 g or more, preferably 1.6 g or more, and more preferably 1.8 g or more per 100 kcal of composition. For example, the total protein content of the composition of the present invention may be 1.5 g or more but less than 2.15 g, 1.5 to 2.05 g, 1.5 to 1.95 g, 1.6 g or more but less than 2.15 g, 1.6 to 2.05 g, 1.6 to 1.95 g, 1.8 g or more but less than 2.15 g, 1.8 to 2.05 g, or 1.8 to 1.95 g per 100 kcal of composition. Alternatively, the total protein content of the composition of the present invention may be less than 11 wt%, more preferably 10.5 wt% or less, and even more preferably 10 wt% or less, based on the total dry weight of the composition. The lower limit of the total protein content may typically be 7.7 wt% or more, preferably 8.2 wt% or more, and more preferably 9.2 wt% or more, based on the total dry weight of the composition. For example, the total protein content of the composition of the present invention may be 7.7 wt% or more but less than 11 wt%, 7.7 to 10.5 wt%, 7.7 to 10 wt%, 8.2 wt% or more but less than 11 wt%, 8.2 to 10.5 wt%, 8.2 to 10 wt%, 9.2 wt% or more but less than 11 wt%, 9.2 to 10.5 wt%, or 9.2 to 10 wt%.

[0031] In the past, infant nutritional compositions tended to contain excessive amounts of total protein in order to ensure the amino acid composition and content found in human breast milk. However, as mentioned above, by reducing the total protein content, the burden on the infant's digestion and metabolism is reduced, and nutritional intake with no excess or deficiency is achieved.

[0032] In the present invention, the term "nutritional composition for infants" refers to a food or drink to be taken orally, and is not particularly limited, but is preferably a formula, a liquid diet, etc., more preferably a formula. The subject of intake may be an infant, a toddler, a child, or an adult, but is preferably an infant. Formulated milk powder is defined in the Ministerial Ordinance on the Compositional Standards of Milk and Dairy Products (Milk Ministerial Ordinance) as "a powder made by processing raw milk, cow's milk, special milk, or foods made from these ingredients, or using them as the main ingredient, and adding nutrients necessary for infants." The ministerial ordinance defines modified liquid milk as "a liquid product made by processing raw milk, cow's milk, special milk, or foods made from these ingredients, or using these as the main ingredient, and adding nutrients necessary for infants." In addition, modified milk is a mixture of various nutritional components such as proteins, fats and oils, carbohydrates, minerals, and vitamins, and includes those processed into powder or liquid form. Furthermore, the term "formulated milk" further includes "powdered infant formula," "liquid infant formula," and "powdered milk for pregnant and lactating women," which are foods for special dietary uses as defined by the Health Promotion Act, as well as forms such as powdered infant formula, nutritional powder for adults, and nutritional powder for the elderly. In the present invention, the "nutritional composition for infants" is more preferably powdered infant formula and liquid infant formula.

[0033] The composition of the present invention usually contains oils and fats in addition to the above-mentioned proteins. Examples of fats and oils include animal fats and oils such as milk fat obtained from the milk of mammals such as cows, buffaloes, goats, and donkeys, fish oil, and egg yolk oil, vegetable fats and oils such as soybean oil, corn oil, sesame oil, perilla oil, rapeseed oil, palm oil, and sunflower oil, as well as fats and oils obtained by culturing microorganisms. In particular, it may contain unsaturated fatty acids that are normally found in breast milk, such as docosahexaenoic acid (DHA), arachidonic acid (ARA), eicosapentaenoic acid (EPA), linoleic acid, gamma-linolenic acid (GLA), alpha-linolenic acid, dihomo-gamma-linolenic acid (DHGLA), and stearidonic acid.

[0034] The compositions of the present invention typically contain carbohydrates. The carbohydrates may include sugars such as lactose, dextrin, starch, raffinose, lactulose, and dietary fibers such as indigestible dextrin and inulin.

[0035] The compositions of the present invention typically contain vitamins. Vitamins include water-soluble vitamins such as B vitamins and vitamin C, and fat-soluble vitamins such as vitamin A, vitamin D, and vitamin E.

[0036] The compositions of the present invention typically contain minerals. The minerals used in the present invention may be salts of sodium, potassium, calcium, iron, zinc, manganese, or copper, and may preferably be incorporated in the form of sodium chloride, potassium chloride, calcium carbonate, ferric pyrophosphate, zinc sulfate, manganese sulfate, copper sulfate, or the like.

[0037] The nutritional composition for infants of the present invention can be produced by conventional methods. The method for producing the composition of the present invention will be described below using the case where the composition is a formula milk as an example. A predetermined amount of prepared milk ingredients containing whey protein, casein, peptides, free amino acids, fats and oils, carbohydrates, vitamins, minerals, etc. are added to water, raw milk, skim milk, whey, etc., and the mixture is heated appropriately to mix and dissolve, followed by heat sterilization to prepare a liquid prepared milk. The fats and oils that are part of the raw materials are heated and melted in advance and added to the raw material solution of the prepared milk. The raw material solution of the prepared milk to which the fats and oils have been added is preferably homogenized using a homogenizer. The fats and oils can be mixed with a solution in which some of the raw materials of the prepared milk have been dissolved, and after homogenization, the remaining raw materials of the prepared milk are added to complete the raw material solution of the prepared milk.

[0038] The liquid formula mixed and prepared as described above is heat sterilized at 75 to 150°C. Heat sterilization methods that can be used include plate sterilization, injection sterilization, and infusion sterilization. Following the heat sterilization step, a homogenization step can be added to adjust the fat globules in the liquid to a uniform size and achieve a good emulsification state. The liquid formula produced by heat sterilization is an intermediate product that can be used to produce the powdered formula described below, and can also be used as a final product in itself. That is, the liquid formula produced by heat sterilization can be hygienically transferred to a filling machine and filled directly into containers made of paper, plastic, aluminum, etc., to produce the final product. In addition, the raw material solution of formula (formulated formula raw material) can also be heat sterilized before mixing with the iron-binding whey protein solution.

[0039] The liquid prepared milk that has been heat-sterilized as described above can be further dried to produce a powdered prepared milk. Before drying, the liquid prepared milk can be concentrated by a conventional method such as vacuum drying. Heat sterilization and drying can also be carried out in a single step. In the drying step, hot air is used. Spray drying or freeze drying can be carried out using hot air. Spray drying using hot air is preferred because it involves heating and therefore exerts a certain degree of sterilization effect. The obtained powder can be filled into a container without adding any additional ingredients to make a product, or it can be mixed with hygienically controlled ingredients, such as lactoferrin, which may be denatured during sterilization, and then filled into a product. [Example]

[0040] The present invention will be explained in more detail below using examples, but the present invention is not limited to these examples.

[0041] Example 1 (1) Preparation of powdered milk According to the formulations shown in Table 2, desalted milk whey protein powder (60% total protein, manufactured by Mirai Co., Ltd.), milk sodium caseinate powder (90% total protein, manufactured by Fonterra), lactose (manufactured by Mirai Co., Ltd.), mineral mixture (manufactured by Tomita Pharmaceutical Co., Ltd.), vitamin mixture (manufactured by Tanabe Pharmaceutical Co., Ltd.), lactulose (manufactured by Morinaga Milk Industry Co., Ltd.), raffinose (manufactured by Nippon Beet Sugar Co., Ltd.), and galactooligosaccharide liquid sugar (manufactured by Yakult Pharmaceutical Co., Ltd.) were dissolved in 300 kg of hot water, further heated and dissolved at 90°C for 10 minutes, and then adjusted fat (manufactured by Taiyo Yushi Co., Ltd.) was added and homogenized. The mixture was then sterilized, concentrated, and spray-dried to prepare approximately 95 kg each of Formulated Milk Powders 1 to 3.

[0042] [Table 2]

[0043] (2) Quantitation of amino acid content The amino acid contents of formula powders 1 to 3 were quantified according to the following method. Table 3 shows the amino acid content of formula powders 1 to 3, along with that of breast milk.

[0044] (i) Methods for quantifying histidine, isoleucine, leucine, lysine, phenylalanine, tyrosine, threonine, valine, aspartic acid + asparagine, serine, glutamic acid + glutamine, glycine, alanine, arginine, and proline 30 mg of a sample of powdered milk was weighed into a glass container, and 3 mL of 6 M hydrochloric acid (containing 0.1% by volume of phenol) (Kokusan Chemical Co., Ltd.) was added. The glass container was then evacuated and sealed. After heating at 110°C for 24 hours to hydrolyze all of the proteins in the sample down to amino acids, the filtrate was filtered through a cotton plug and placed in an evaporator to remove the hydrochloric acid. The sample was then redissolved in 5 mL of 0.02 M hydrochloric acid. The redissolved sample and an amino acid standard (Fujifilm Wako Pure Chemical Industries, Ltd.) were then placed in a high-speed amino acid analyzer "L-8900" (Hitachi High-Technologies Corporation). The content of each amino acid in the sample was then quantified.

[0045] (ii) Method for quantifying methionine and cysteine A performic acid solution was prepared by mixing 30% hydrogen peroxide (Kokusan Chemical) and 99% formic acid (Fujifilm Wako Pure Chemical Industries, Ltd.) in a 1:9 (volume ratio). 30 mg of infant formula powder sample was weighed into a glass container, 3 mL of performic acid was added, and the container was sealed with parafilm and left at 4°C for 18 hours to convert cysteine ​​(cystine) to cysteic acid and methionine to methionine sulfone. The glass container was heated to 65°C in a heat block and the performic acid was removed by blowing nitrogen. 3 mL of 6 M hydrochloric acid (containing 0.1% phenol by volume) was then added, and the glass container was degassed and sealed. After hydrolysis at 110°C for 18 hours, the filtrate was filtered through a cotton plug and the hydrochloric acid was removed using an evaporator. The sample was then redissolved in 5 mL of 0.02 M hydrochloric acid. The reconstituted sample, a methionine sulfone standard (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.), and a cysteic acid standard (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) were subjected to a high-speed amino acid analyzer "L-8900" (manufactured by Hitachi High-Technologies Corporation), and the methionine and cysteine ​​contents in the sample were quantified.

[0046] (iii) Method for quantifying tryptophan Thiodiethylene glycol (Fujifilm Wako Pure Chemical Industries, Ltd.) and ultrapure water were mixed at a volume ratio of 6:4 to obtain a 60% thiodiethylene glycol solution. 20 mg of infant formula powder sample was weighed into a glass container, and 1.56 g of barium hydroxide pentahydrate (Fujifilm Wako Pure Chemical Industries, Ltd.), 0.9 ml of ultrapure water, and 0.1 mL of 60% thiodiethylene glycol were added. The glass container was then degassed and sealed. After hydrolysis at 110°C for 12 hours, the solution was neutralized and diluted to pH 7-9 with 6 M hydrochloric acid (Kokusan Chemical Co., Ltd.) and diluted to 50 mL with ultrapure water. The diluted sample and a tryptophan standard (Fujifilm Wako Pure Chemical Industries, Ltd.) were subjected to high-performance liquid chromatography (Shimadzu Corporation) equipped with a fluorescence detector (Ex. 285 nm, Em. 348 nm) to quantify the tryptophan content in the sample.

[0047] [Table 3]

[0048] (3) Quantitative determination of casein content Casein standard (Sigma-Aldrich, Catalog No. C7078) was dissolved in 8M urea solution to give total protein concentrations of 0.27, 0.67, and 1.07 mg protein / mL, and infant formula 1 to 3 were dissolved in 8M urea solution to give a total protein concentration of 1.33 mg protein / mL. After adding 1 / 4 volume of 4x Laemmli sample buffer (Bio-Rad, catalog number: 1610747) containing 10% 2-mercaptoethanol (Bio-Rad), the mixture was heat-denatured at 95°C for 5 minutes, and 10 μL of the mixture was applied to each well of an SDS-PAGE gel (Bio-Rad, catalog number: 456-9036) in electrophoresis buffer (Bio-Rad, catalog number: 1610377). The total protein amounts applied were 2, 5, and 8 μg for the casein standard and 10 μg for the formulas 1 to 3. The gel was electrophoresed at 150V for 45 minutes and stained with Coomassie Blue stain (Bio-Rad, Catalog No. 456-9034). An electrophoresis image was then created using a ChemiDoc XRS+ imaging system (Bio-Rad). The bands corresponding to casein in each lane in the image were selected using the Volume Tools function of Image Lab software (Bio-Rad), and the band intensities were calculated (Figure 1). The casein content per 10 μg of total protein in formula powders 1-3 was calculated based on a calibration curve constructed from the total protein mass of the three casein standards and the band intensities corresponding to those protein masses. The bands selected were those near the center of the image, 20 μg. The bands in each lane were selected to cover the same area, including α-casein, β-casein, and γ-casein, which are located in the ~37 kDa range. The casein contents per 10 μg of total amino acids in Formulas 1 to 3 were 3.2, 4.4, and 5.9 μg, respectively. This indicates that the casein contents per 10 μg of total protein in Formulas 1 to 3 were 32 wt%, 44 wt%, and 59 wt%, respectively.

[0049] (4) Administration test on rats Six-week-old male SD rats were purchased from Charles River Japan. After 12 days of acclimation on a regular diet, they were divided into three groups (n = 5) to ensure even weight distribution. Each group was then switched to one of the formula milk powders 1, 2, or 3 for one week. Blood samples were collected on the final day of the study and plasma samples were prepared. Food intake and body weight were recorded daily to ensure no significant differences were observed among the groups. An equal volume of 10% trichloroacetic acid solution was added to the plasma sample, and the mixture was centrifuged at 21,500 g for 15 minutes to obtain the supernatant. The supernatant and amino acid standards (Fujifilm Wako Pure Chemical Industries, Ltd.) were then used to quantify the free amino acid concentrations in the plasma using a high-speed amino acid analyzer (L-8900, Hitachi High-Technologies Corporation). Table 4 shows the plasma free amino acid concentrations in rats that ingested formulas 1 to 3.

[0050] [Table 4]

[0051] It is widely known that when a specific essential amino acid is deficient in the body, the plasma free amino acid concentration of that amino acid decreases, and when a specific essential amino acid is ingested in excess, the plasma free amino acid concentration of that amino acid increases (Physiological reviews 50 P428 (1970)). In other words, the plasma free amino acid concentration of essential amino acids can be said to be an index that reflects the excess or deficiency of amino acid nutrition in the body.

[0052] The total protein content of Formula 2 and Formula 3 according to the present invention was lower than that of Formula 1, but as shown in Table 3, the plasma free amino acid concentrations of essential amino acids in Formula 2 and Formula 3 were equal to or higher than the plasma free amino acid concentrations in Formula 1, except for threonine. The plasma free threonine concentration in the formula 2 group was significantly lower than that in the formula 1 group. However, as mentioned above, it has been pointed out that the threonine content in conventional formulas is excessive compared to breast milk (Table 1), so formula 2 is thought to provide more desirable amino acid nutrition for human infants. Furthermore, the plasma free tyrosine concentration in the formula 3 group was significantly higher than that in the formula 1 group. However, as mentioned above, it has been pointed out that the total content of tyrosine and phenylalanine in conventional formulas is insufficient compared to breast milk (Table 1). Therefore, formula 3 is thought to provide more desirable amino acid nutrition for human infants.

[0053] In other words, the present invention provides a nutritional composition for infants that has an amino acid composition closer to that of breast milk, by reducing the total protein content and ensuring sufficient amino acid nutrition without excessive protein intake.

Claims

1. 1. A protein-containing infant nutritional composition comprising: The total content of phenylalanine and tyrosine per total amino acid is 7.6% by weight or more, The total protein content is less than 2.15 g per 100 kcal of the composition; and More than 90% by weight of the total protein is derived from milk, 41 to 70% by weight of the total protein is casein, A nutritional composition for infants (excluding breast milk), in which the ratio of tryptophan content to the total content of phenylalanine and tyrosine is 21% by weight or less.

2. The composition according to claim 1, wherein the tyrosine content per total amino acid is 3.6% by weight or more.

3. 3. The composition according to claim 1, wherein the phenylalanine content per total amino acid is 3.8% by weight or more.

4. The composition according to any one of claims 1 to 3, which is a formula.

Images