Powdered milk, method for producing solid milk, solid milk, and method for measuring average sphericity of powder

Abstract

Provided are: powdered milk having excellent formability; a method for producing solid milk using the same; and solid milk. The present invention also provides a method which is for measuring the average sphericity of a powder, and with which it is possible to analyze the shape of a powder in which fine particles are aggregated. Powdered milk 1 according to the present embodiment has an average sphericity Φave of 0.66 or less. The average sphericity is measured by a measurement method including the following steps (a)-(c). (a) An image acquisition step for acquiring a three-dimensional image obtained by imaging each particle constituting powdered milk. (b) A three-dimensional model creation step for creating a three-dimensional model of each particle constituting the powdered milk on the basis of the three-dimensional image. (c) An average sphericity calculation step for calculating the average sphericity of the powdered milk from the three-dimensional model of each particle constituting the milk powder. Due to said feature, the present embodiment can provide powdered milk 1 having excellent formability.

Description

Method for producing powdered milk and solid milk, and method for measuring the average sphericity of solid milk and powder.

[0001] This invention relates to a method for producing powdered milk and solid milk, solid milk, and a method for measuring the average sphericity of powders.

[0002] Powdered milk is a powder produced, for example, by removing water from milk. In recent years, solid milk, which is produced by compressing and molding powdered milk, has become known as a solid food product (see, for example, Patent Document 1). By solidifying powdered milk in this way, its shape can be maintained, and users can easily hold it even though it is in powder form.

[0003] Patent No. 4062357

[0004] In producing such solid milk, the development of powdered milk with excellent moldability is desirable. Furthermore, analyzing the shape of the powdered milk is important when determining whether or not it has excellent moldability. Shape analysis is a technique that deserves attention not only for powdered milk, but also for powders composed of fine particles similar to powdered milk.

[0005] This invention has been made in view of the above problems, and aims to provide a powdered milk with excellent moldability, a method for producing solid milk using the same, and solid milk. Furthermore, this invention aims to provide a method for measuring the average sphericity of a powder that can perform shape analysis of a powder composed of fine particles.

[0006] The powdered milk according to the present invention has an average sphericity of 0.66 or less. The average sphericity is measured by a measurement method including the following steps (a) to (c): (a) an image acquisition step of acquiring a three-dimensional image of each particle constituting the powdered milk; (b) a three-dimensional model creation step of creating a three-dimensional model of each particle constituting the powdered milk based on the three-dimensional image; (c) an average sphericity calculation step of calculating the average sphericity of the powdered milk from the three-dimensional model of each particle constituting the powdered milk.

[0007] Furthermore, the method for producing solid milk according to the present invention includes a compression step in which powdered milk with an average sphericity of 0.66 or less is compressed and molded to produce the solid milk.

[0008] Furthermore, the solid milk according to the present invention is solid milk produced by the manufacturing method described above, having a tensile strength of 90 kPa or more, or a porosity of 30% or more.

[0009] Furthermore, the method for measuring the average sphericity of a powder according to the present invention includes an image acquisition step of acquiring a three-dimensional image of each particle constituting the powder, a three-dimensional model creation step of creating a three-dimensional model of each particle constituting the powder based on the three-dimensional image, and an average sphericity calculation step of calculating the average sphericity of the powder from the three-dimensional model of each particle constituting the powder.

[0010] According to the present invention, it is possible to provide a powdered milk with excellent moldability, a method for producing solid milk using the same, and solid milk. Furthermore, it is possible to provide a method for measuring the average sphericity of a powder, which can perform shape analysis of a powder composed of fine particles.

[0011] This is an X-ray CT image of the powdered milk according to this embodiment, captured by an X-ray CT scanner. This is a flowchart of the average sphericity calculation procedure. This is a three-dimensional model of the generated powdered milk. 4A is a graph showing the relationship between granulation time and average sphericity, and 4B is a graph showing the relationship between porosity and tensile strength for Examples 1 to 3 and Comparative Example 1. 5A is a graph showing the average sphericity for Examples 4 to 11, and 5B is a graph showing the average sphericity for Comparative Examples 2 to 16. This is a graph showing the relationship between porosity and tensile strength for Examples 4 to 11 and Comparative Examples 2 to 16. This is a graph showing the relationship between average sphericity and moldability index.

[0012] Embodiments of the present invention will be described below. In the following description, components identical to those already described will be denoted by the same reference numerals and their descriptions will be omitted.

[0013] (1) Composition of powdered milk (1-1) Schematic diagram 1 of the powdered milk is an X-ray CT (Computed Tomography) image of the powdered milk according to this embodiment, taken with an X-ray CT (Computed Tomography) device. As shown in Figure 1, the powdered milk 1 according to this embodiment is a powder made up of particles. The powdered milk 1 has irregularly formed bumps and dips, such as fine spherical particles and elliptical particles that are bonded together, and has an overall irregular external shape.

[0014] The average particle size of the particles constituting the milk powder 1 according to this embodiment is approximately 100 [μm] to 500 [μm]. The average particle size of the milk powder 1 (more specifically, the average particle size of the particles constituting the milk powder 1) can be measured using a laser diffraction particle size distribution analyzer (Mastersizer 3000 (manufactured by Malvern)).

[0015] The powdered milk 1 according to this embodiment can be solidified by compression molding to produce solid milk. The solid milk contains numerous voids (e.g., pores) that are created when the raw material powdered milk 1 is compressed. It is preferable that these multiple voids are uniformly dispersed (distributed) in the solid milk, which allows the solid milk to dissolve without bias and improves the solubility of the solid milk.

[0016] It is preferable that the solid milk has a tensile strength of 90 kPa or higher, as measured by the method described later in "(3-2) Relationship between the porosity of the molded product and the tensile strength of the molded product". By setting the tensile strength of the solid milk to 90 kPa or higher, strength can be imparted to the solid milk, preventing cracking or chipping. Furthermore, by setting the tensile strength of the solid milk to 120 kPa or higher, cracking or chipping of the solid milk due to external forces during transportation can be further prevented. Moreover, by setting the tensile strength of the solid milk to 150 kPa or higher, resistance to external forces during transportation can be further improved, and cracking or chipping of the solid milk can be prevented even more reliably.

[0017] Furthermore, it is preferable that the solid milk has a tensile strength of 300 [kPa] or less, as measured by the method described later in "(3-2) Relationship between the porosity of the molded product and the tensile strength of the molded product". By setting the tensile strength of the solid milk to 300 [kPa] or less, the decrease in solubility and disintegration can be suppressed, and by setting it to 250 [kPa] or less, the decrease in solubility and disintegration can be suppressed even further.

[0018] Based on the above, the tensile strength of the solid milk is preferably 90 kPa or more and 300 kPa or less, and more preferably 150 kPa or more and 250 kPa or less. Furthermore, the tensile strength of the solid milk is also preferably 90 kPa or more and 250 kPa or less, and also preferably 150 kPa or more and 300 kPa or less. In order to provide the solid milk with optimal strength, optimal solubility and disintegration properties depending on the transport and usage conditions, it is preferable to select one of the above-mentioned ranges of tensile strength.

[0019] Furthermore, the porosity of solid milk can be suppressed by setting it to 30% or higher, as measured by the method described later in "(3-2) Relationship between the porosity of molded products and the tensile strength of molded products." In addition, the porosity of solid milk can be further suppressed by setting it to 35% or higher, or 40% or higher, thereby achieving optimal solubility and disintegration depending on the intended use. Moreover, by setting the porosity of solid milk to 50% or lower, strength can be imparted to the solid milk, preventing cracking or chipping. Furthermore, by setting the porosity of solid milk to 45% or lower, cracking or chipping of the solid milk due to external forces during transportation can be further prevented.

[0020] Based on the above, the porosity of the solid milk is preferably 30% to 50%, and more preferably 30% to 45%. Furthermore, the porosity of the solid milk is also preferably 35% to 50%, and more preferably 35% to 45%. Furthermore, the porosity of the solid milk is also preferably 40% to 50%, and more preferably 40% to 45%. In order to impart optimal strength, optimal solubility, and disintegration properties to the solid milk depending on the transport and usage conditions, it is preferable to select one of the above-mentioned porosity ranges.

[0021] Moreover, the milk powder 1 according to the present embodiment is the milk powder 1 for use in a method for producing solid milk that solidifies by compression molding. Further, the milk powder 1 according to the present embodiment is used for use in the production of solid milk that solidifies by compression molding.

[0022] (1-2) The raw material milk powder 1 of the milk powder is produced from liquid milk (liquid milk) containing milk components (for example, components of cow's milk). The milk components are, for example, raw milk (whole milk), skim milk, cream, and the like. The water content of the liquid milk is, for example, 40 [wt%] to 95 [wt%]. The water content of the milk powder 1 is, for example, 1 [wt%] to 4 [wt%]. The milk powder 1 may be added with nutritional components described later. The milk powder 1 may be whole milk powder, skim milk powder, or creamy powder. The fat content of the milk powder 1 is preferably, for example, 5 [wt%] to 70 [wt%].

[0023] The milk components that are the raw materials of the above milk powder 1 are, for example, derived from raw milk. Specifically, they are derived from raw milk such as cows (Holstein, Jersey and others), goats, sheep, and water buffalo. Although the above raw milk contains fat, it may be milk with an adjusted fat content in which part or all of the fat has been removed by centrifugation or the like.

[0024] Further, the milk components that are the raw materials of the above milk powder 1 are, for example, plant-derived plant milk. Specifically, they are derived from plants such as soy milk, rice milk, coconut milk, almond milk, hemp milk, and peanut milk. Although the above plant milk contains fat, it may be milk with an adjusted fat content in which part or all of the fat has been removed by centrifugation or the like.

[0025] The nutritional components that are the raw materials of the above milk powder 1 are, in addition to the above milk components, for example, fat, protein, carbohydrates, minerals, vitamins, and the like. One or more of these may be added.

[0026] The proteins that can be the raw materials of the above-mentioned powdered milk 1 are, for example, milk proteins and milk protein fractions, animal proteins, plant proteins, peptides and amino acids obtained by decomposing these proteins into various chain lengths with enzymes or the like. One or more of these may be added. Milk proteins include, for example, casein, whey proteins (α-lactalbumin, β-lactoglobulin, etc.), and milk protein fractions include, for example, whey protein concentrate (WPC) and whey protein isolate (WPI). Animal proteins are, for example, egg proteins. Plant proteins are, for example, soybean proteins and wheat proteins. Amino acids are, for example, taurine, cysteine, cystine, arginine, and glutamine.

[0027] The fats (oils and fats) that can be the raw materials of the above-mentioned powdered milk 1 are animal fats and oils, vegetable fats and oils, their fractionated oils, hydrogenated oils, and interesterified oils. One or more of these may be added. Animal fats and oils are, for example, milk fat, lard, beef tallow, and fish oil. Vegetable fats and oils are, for example, soybean oil, rapeseed oil, corn oil, coconut oil, palm oil, palm kernel oil, safflower oil, cottonseed oil, linseed oil, and MCT (Medium Chain Triglyceride) oil.

[0028] The carbohydrates that can be the raw materials of the above-mentioned powdered milk 1 are, for example, oligosaccharides, monosaccharides, polysaccharides, and artificial sweeteners. One or more of these may be added. Oligosaccharides are, for example, lactose, sucrose, maltose, galactooligosaccharide, fructooligosaccharide, lactulose, etc. Monosaccharides are, for example, glucose, fructose, and galactose. Polysaccharides are, for example, starch, soluble polysaccharides, and dextrin. Note that instead of or in addition to the artificial sweeteners of carbohydrates, non-carbohydrate artificial sweeteners may be used.

[0029] Minerals that can be used as ingredients for the above-mentioned powdered milk 1 include, for example, sodium, potassium, calcium, magnesium, iron, copper, and zinc. One or more of these may be added. In addition, phosphorus compounds and chlorine compounds, or one or both, may be used instead of or in addition to the minerals sodium, potassium, calcium, magnesium, iron, copper, and zinc.

[0030] (1-3) Average sphericity of the powdered milk 1 is preferably 0.66 or less. Sphericity is one of the "shape constants" that define the shape of an object, and the closer its value is to 1, the closer it is to a perfect sphere. By setting the average sphericity of the powdered milk 1 to 0.66 or less, it is possible to produce solid milk that is excellent in compression molding when manufacturing solid milk and has an appropriate hardness (strength) and an appropriate porosity. In other words, by setting the average sphericity of the powdered milk to 0.66 or less, the irregularities formed on the surface of each powdered milk increase the contact points and non-contact area between powdered milk when the powdered milk 1 is compressed and molded, thereby achieving excellent moldability (appropriate hardness and appropriate porosity). Note that when the number of contact points between powdered milk 1 increases, contact occurs at many points, so the contact area of ​​each contact point becomes smaller.

[0031] Furthermore, it is more preferable that the average sphericity of the milk powder 1 be 0.60 or less, even more preferable that it be 0.59 or less, even more preferable that it be 0.55 or less, and most preferable that it be 0.50 or less. By setting the average sphericity of the milk powder 1 to 0.60 or less, 0.59 or less, 0.55 or less, and even 0.50 or less, when the milk powder 1 is compressed and molded, the contact points and non-contact area between the milk powders increase, resulting in even better moldability.

[0032] It is preferable that the average sphericity of powdered milk 1 is 0.10 or higher. By setting the average sphericity of powdered milk 1 to 0.10 or higher, it is possible to reduce the size of the drying equipment used during production and shorten the time required for granulation, thereby reducing the burden during production. Furthermore, it is more preferable that the average sphericity of powdered milk 1 be 0.24 or higher, even more preferable that it be 0.30 or higher, even more preferable that it be 0.36 or higher, and most preferably that it be 0.45 or higher. By setting the average sphericity of powdered milk 1 to 0.24 or higher, 0.30 or higher, 0.36 or higher, and even 0.45 or higher, it is possible to further shorten the time required for granulation, thereby further reducing the burden during production.

[0033] Based on the above, it is preferable that the average sphericity of powdered milk 1 is 0.10 or more and 0.66 or less, more preferably 0.10 or more and 0.60 or less, more preferably 0.10 or more and 0.59 or less, more preferably 0.10 or more and 0.55 or less, and more preferably 0.10 or more and 0.50 or less. Furthermore, it is preferable that the average sphericity of powdered milk 1 is 0.24 or more and 0.66 or less, more preferably 0.24 or more and 0.60 or less, more preferably 0.24 or more and 0.59 or less, more preferably 0.24 or more and 0.55 or less, and more preferably 0.24 or more and 0.50 or less. Furthermore, it is preferable that the average sphericity of powdered milk 1 is 0.30 or more and 0.66 or less, more preferably 0.30 or more and 0.60 or less, more preferably 0.30 or more and 0.59 or less, more preferably 0.30 or more and 0.55 or less, and more preferably 0.30 or more and 0.50 or less.

[0034] Furthermore, it is preferable that the average sphericity of powdered milk 1 is 0.36 or more and 0.66 or less, more preferably 0.36 or more and 0.60 or less, more preferably 0.36 or more and 0.59 or less, more preferably 0.36 or more and 0.55 or less, and more preferably 0.36 or more and 0.50 or less. Furthermore, it is preferable that the average sphericity of powdered milk 1 is 0.45 or more and 0.66 or less, more preferably 0.45 or more and 0.60 or less, more preferably 0.45 or more and 0.59 or less, more preferably 0.45 or more and 0.55 or less, and more preferably 0.45 or more and 0.50 or less. It is preferable to select powdered milk 1 to be within any of the above-mentioned ranges of average sphericity depending on the conditions of the manufacturing equipment and the degree to which the burden during manufacturing is reduced.

[0035] Next, the procedure for calculating the average sphericity of powdered milk 1 will be explained. Figure 2 is a flowchart of the procedure for calculating the average sphericity of powdered milk 1. Here, in measuring the average sphericity of powdered milk 1, the three-dimensional shape of each particle constituting the powdered milk 1 is grasped and the surface area of ​​the particle surface is detected. In the procedure for calculating the average sphericity of powdered milk 1, first, in step S1, the total weight w1 [mg] of a predetermined number (n particles) constituting the powdered milk 1 is measured using a weighing scale (total weight measurement step). In step S1, powdered milk 1 is loosely filled into a Φ2.5 [mm] polyimide tube to a height of about 2 [mm] (for example, to about 5 [mg]), and the total weight w1 of powdered milk 1 inside the tube is measured using a weighing scale.

[0036] Next, in step S2, the particle density ρ [kg / m³] of a predetermined number (n) of particles is determined. ３ ] and the true density of particles ρt [kg / m³] ３ ] and (the particle density ρ [kg / m³] of a predetermined number (n) of particles ３ ] and true density ρt [kg / m³] ３] and (measurement) (particle density / true density measurement process). Particle density ρ is preferably measured using the particle density measuring device "AccuPic II 1345 (manufactured by Shimadzu Corporation)". Particle density ρ is the density including the internal voids of the particle. True density ρt is the density for which only the volume occupied by the particle itself (the volume occupied by the powder layer of the particle itself) is used as the volume for density calculation. True density ρt can be measured by crushing the particle. Here, the powder layer is the "real part" of the particle excluding the internal voids of the particle, and refers to the region of the solid part that constitutes the particle.

[0037] Next, in step S3, the processing unit acquires a plurality of X-ray CT images of a predetermined number (n) of particles (image acquisition step). In step S3, the internal structure of each particle of the powdered milk 1 (powder) inside the tube, which is filled into the tube as described above, is imaged using an X-ray CT scanner (manufactured by Rigaku Corporation, product name "Nano3DX" (registered trademark)).

[0038] The imaging conditions are as follows: L1080 is used as the X-ray camera lens of the X-ray CT apparatus, Mo (molybdenum) is used as the target of the X-ray tube, the imaging range is Φ3.6 [mm] × H2.8 [mm], binning is 3, resolution (spatial resolution) is 3.3 [μm / voxel], and exposure time is 4 [sec]. In step S3, multiple X-ray CT images (for example, 600 images) are obtained by imaging the powdered milk 1 in the tube from various angles using the above imaging conditions, and the process moves to the next step S4. Here, for example, if the height direction of the tube into which the powdered milk 1 is introduced is defined as the z axis, one direction in the in-plane direction perpendicular to the z axis of the tube is defined as the x axis, and the direction perpendicular to the x axis and z axis in that in-plane direction is defined as the y axis, the powdered milk 1 in the tube is imaged from various angles using the X-ray CT apparatus, and an X-ray CT image is obtained in which the density is shown as brightness information for each xyz axis coordinate inside the tube. The processing unit can generate a three-dimensional image representing powdered milk 1 in three dimensions from multiple X-ray CT images. The term "X-ray CT image" below also includes the three-dimensional image generated from multiple X-ray CT images.

[0039] Next, in step S4, a threshold value is assumed for the binarization of multiple X-ray CT images, each containing a predetermined number of acquired particles, by the processing unit (threshold setting step).

[0040] More specifically, in the threshold setting step S4, a threshold is assumed for the binarization of each voxel (each pixel when processing each of the two-dimensional X-ray CT images (slice images)) in the three-dimensional X-ray CT image of a predetermined number of acquired particles, in order to distinguish between the powder layer and the spatial layer.

[0041] Here, in powdered milk 1, the gaps between adjacent particles and the internal voids of each particle are referred to as space layers, and in some explanations, the combined gaps between particles and the internal voids of each particle are also referred to as the space layer. A particle refers to the powder layer plus the internal voids within the space layer. The binarization threshold for the X-ray CT image is a threshold used to distinguish the outer shape of each particle, the gaps between adjacent particles (space layer), and the internal voids of each particle (space layer). The processing unit is a computer capable of performing calculations and image processing such as binarization. Next, in step S5, the processing unit acquires a predetermined number of binarized images of the X-ray CT image by binarizing it with the set binarization threshold (binarized image acquisition step), and then moves to the next step S6. More specifically, in the binarized image acquisition step S5, the X-ray CT image is binarized using the binarization threshold set in step S4 to acquire a binarized image showing the powder layer region, which is the actual part of a predetermined number of particles excluding internal voids.

[0042] In step S6, the processing unit calculates the theoretical total volume v1 [m³] of a predetermined number (n) of particles from the total weight w1 of the powdered milk 1 in the tube and the true density of the particles (i.e., the true density of the powdered milk 1). ３ ] is the total volume v2 [m³] of the predetermined number of particles in the binarized image. ３ Determine whether it is equal to ] (volume determination step).

[0043] More specifically, in the volume determination step S6, the theoretical total volume v1 [m³] of the powder layer, which is the actual portion of a predetermined number (n particles), is calculated from the true density of the powdered milk 1 and the total weight w1 of the powdered milk 1 in the tube. ３ ] is the total volume v2 [m³] of the powder layer, which is the actual portion of the predetermined number of particles in the binarized image. ３ Determine whether it is equal to ].

[0044] The theoretical total volume v1 of a predetermined number of particles (i.e., the theoretical total volume of the powder layer, which is the actual part of the predetermined number of particles) is calculated by the total weight w1 / true density ρt. The total volume v2 of a predetermined number of particles in a binarized image (i.e., the total volume of the powder layer, which is the actual part of the predetermined number of particles in a binarized image) is calculated, for example, from a predetermined number of particles identified from within the binarized image by image processing.

[0045] Specifically, the total volume v2 is calculated by summing the volumes of the powder layers of each slice image of the binarized X-ray CT image. The volume of the powder layer of each slice image is calculated by multiplying the area of ​​the powder layer in each slice image by the slice pitch (the distance between each slice). The area of ​​the powder layer in each slice image is calculated by multiplying the area of ​​the image pixels by the number of pixels in the powder layer.

[0046] Here, if the binarization threshold used when binarizing the X-ray CT image in step S5 is an appropriate value, the theoretical total volume v1 will be equal to the total volume v2. On the other hand, if the binarization threshold used when binarizing the X-ray CT image in step S5 is not an appropriate value, the theoretical total volume v1 will not be equal to the total volume v2. The theoretical total volume v1 being equal to the total volume v2 means that the binarization threshold that minimizes the error between V1 and V2 is set.

[0047] If a negative result is obtained in step S6, this indicates that the theoretical total volume v1 is not equal to the total volume v2. At this time, the arithmetic processing unit proceeds to the next step S7. In step S7, the arithmetic processing unit corrects the threshold value used to binarize the X-ray CT image in step S5 (threshold correction step), and returns to step S5 again. When the total volume v2 is larger than the theoretical total volume v1, the threshold value for binarization is corrected in the direction in which the total volume v2 becomes smaller. When the total volume v2 is smaller than the theoretical total volume v1, the threshold value for binarization is corrected in the direction in which the total volume v2 becomes larger. Note that the correction of the binarization threshold value may be arbitrarily corrected to any value by the user, or the value of the threshold may be automatically corrected at a predetermined interval by the arithmetic processing unit. In step S5, the arithmetic processing unit binarizes the X-ray CT image with the threshold value corrected in step S7, and obtains a binarized image of a predetermined number of particles. Thereafter, the threshold value for binarization is corrected and the above-described processing is repeated until an affirmative result is obtained in step S6.

[0048] On the other hand, if an affirmative result is obtained in step S6, this indicates that the theoretical total volume v1 is equal to the total volume v2. At this time, the arithmetic processing unit proceeds to the next step S8. In step S8, the arithmetic processing unit assumes the maximum internal void volume v3 [m ３ . The maximum internal void volume v3 is the volume of the largest internal void among the plurality of internal voids existing in one particle, and is defined as the volume of the internal void assumed to be the largest among the plurality of particles included in the whole milk powder 1 as one maximum internal void volume v3 for the whole milk powder 1. Such a maximum internal void volume v3 can be assumed not only by direct particle observation (for example, analyzing particles based on an X-ray CT image) but also by domain knowledge (for example, knowledge of the foam drying method for creating internal voids described later).

[0049] Next, in step S9, the processing unit uses image processing to fill in the internal voids within each of the predetermined number of particles identified in the binarized image, up to a maximum internal void volume v3, and then proceeds to the next step S10. For example, in a binarized image, the solid part of a particle is represented in white, and the internal voids inside the particle are represented in black (a different color from the solid part). In this case, the processing unit fills in the black areas representing internal voids within the display area of ​​the predetermined number of particles in the binarized image with white, and generates a binarized image in which the internal voids inside the particles up to a maximum internal void volume v3 are filled and removed by image processing.

[0050] In step S10, the arithmetic processing unit determines whether the total internal porosity ε1 of a predetermined number of particles, calculated from the true density of the particles (i.e., the true density of the powdered milk 1) ρt and the particle density ρ, is equal to the total internal porosity of a predetermined number of particles (hereinafter also referred to as the estimated internal porosity) ε2 obtained in step S9 from the binarized image obtained by removing internal voids based on the maximum internal void volume v3 (porosity determination step). The estimated internal porosity ε2 can be obtained by the arithmetic processing unit by performing image analysis on the binarized image. When the internal porosity ε1 and the internal porosity ε2 are equal, it means that the maximum internal void volume v3 is set such that the error between the internal porosity ε1 and the internal porosity ε2 is minimized.

[0051] If a negative result is obtained in step S10, this indicates that the internal porosity ε1 calculated from the true density of the particles (i.e., the true density of powdered milk 1) ρt and the particle density ρ is not equal to the estimated internal porosity ε2 of the binarized image, and in this case the processing unit moves on to the next step S11.

[0052] In step S11, the processing unit modifies the maximum internal void volume v3, which is the standard for filling the internal voids in step S9, and returns to step S9 (void volume modification step). If the estimated internal void ratio ε2 is greater than the internal void ratio ε1, the value of the maximum internal void volume v3 is modified in the direction that the estimated internal void ratio ε2 becomes smaller. Also, if the estimated internal void ratio ε2 is smaller than the internal void ratio ε1, the value of the maximum internal void volume v3 is modified in the direction that the estimated internal void ratio ε2 becomes larger. Note that the maximum internal void volume v3 may be modified to an arbitrary value by the user, or the processing unit may automatically modify the value of the maximum internal void volume v3 at predetermined intervals. In step S9, the processing unit fills the internal voids surrounded by the outer shell of the particles that are less than or equal to the maximum internal void volume v3 modified in step S11. Thereafter, the maximum internal void volume v3 is modified and the above process is repeated until a positive result is obtained in step S10.

[0053] On the other hand, if a positive result is obtained in step S10, this indicates that the true density of the particles (i.e., the true density of powdered milk 1) ρt and the internal porosity ε1 calculated from the particle density ρ are equal to the estimated internal porosity ε2 of the binarized image, and at this point the processing unit moves on to the next step S12.

[0054] In step S12, the processing unit creates a three-dimensional model of a predetermined number of particles from a binarized image of the predetermined number of particles (three-dimensional model creation step). In this case, in step S12, the processing unit uses the marching cube method to convert the voxel model of each particle, which is volume data represented by a large number of voxels in the binarized image, into a polygon model to create a predetermined number (n) of three-dimensional models. Figure 3 shows an example of a three-dimensional model of one powdered milk 1 that has been generated.

[0055] It should be noted that a 3D model is a polygonal model of a three-dimensional structure that contains volume and area information, and is different from a 3D X-ray CT image, which is a collection of multiple images that contain height information. Even with 2D imaging data, it is possible to extract volume and area information by integrating the data without creating a 3D model, for example, by assuming that the relationship between two images can be approximated by a trapezoid. On the other hand, in such 2D approximation calculations, if the curvature of the powder is high or the anisotropy of the powder is high, the area and volume information may differ depending on the orientation of the 2D image, and the shape may not be accurately extracted.

[0056] A three-dimensional model is shape information extracted from all the scalar information of voxels distributed and adjacent in three dimensions. Compared to methods such as mathematically approximating shape information from one-dimensional adjacent information in one direction using trapezoidal approximation, it can accurately extract shape information such as volume and area, making it suitable for sphericity measurement, which can be used to measure complex particle morphologies.

[0057] In step S12, a three-dimensional model of a predetermined number of particles is created from a binarized image of a predetermined number of particles. For example, the three-dimensional model, which is a polygon, has an area A (for example, 100 [μm²]). ２ ) If there is a constriction below the ]) it is preferable to recognize the constriction as a separate particle. The area A of the constriction that distinguishes the polygon as a separate particle is adjusted, for example, so that the median diameter of the 3D model generated by distinguishing and separating the polygon as a separate particle from the constriction is equal to the median diameter of the 3D model calculated by a laser diffraction particle size distribution analyzer (Mastersizer 3000 (Malvern Corporation)).

[0058] Next, in step S13, the arithmetic processing unit calculates the volume Vi and surface area Si of a predetermined number (n) of 3D models i (where i is an identifier for the 3D model and is an integer from 1 to n) from the 3D image according to the marching cube method. For example, in step S13, the arithmetic processing unit calculates the average sphericity Φave, which is the average sphericity of the predetermined number (n) of 3D models i, based on the calculated volume Vi and surface area Si of the 3D models i, from the following equation (1) (average sphericity calculation step), and terminates the average sphericity calculation procedure described above.

[0059]

[0060] In this embodiment, the X-ray CT image is binarized to identify each particle stacked within the X-ray CT image, and a three-dimensional model is generated for each identified particle using the marching cubes method. When performing the binarization process, it is preferable to set the threshold value during the binarization process and the maximum internal void volume v3 to optimal values ​​in order to prevent errors from being introduced during the marching cubes method (for example, to prevent the generation of a three-dimensional model by identifying multiple particles as a single particle). This makes it possible to create a three-dimensional model that accurately reproduces the shape of each particle from the binarized image generated based on the X-ray CT image.

[0061] The average sphericity Φave is the arithmetic mean of the calculated sphericity Φi of each particle. In this invention, since the true three-dimensional sphericity reflecting curvature can be calculated based on the volume and surface area obtained from the three-dimensional polygon model generated by the marching cube method, the curvature-dependent error that occurs in volume estimation using multiple two-dimensional cross-sectional images can be reduced.

[0062] Furthermore, in the X-ray CT image of powdered milk 1, the density difference between air and powdered milk 1 is extremely large, making it easy to detect the interface between gas and solid. Therefore, it can be said that the measurement results do not differ significantly depending on the measurement conditions when detecting the presence or absence of an object.

[0063] If the resolution of the X-ray CT scanner is significantly changed, the sphericity value of powdered milk 1 may become inaccurate. A significant change in resolution allows for the observation of finer undulations of powdered milk 1, thus increasing the area value. Therefore, a resolution of 1 / 150 to 1 / 30 of the average particle diameter of powdered milk 1 (approximately 2 to 10 μm) allows for measurement of sphericity with almost no error. The average particle diameter of powdered milk 1 is determined using a laser diffraction particle size distribution analyzer (Mastersizer 3000 (Malvern)). For example, in the case of powdered milk 1 with an average particle diameter of around 100 [μm], the average sphericity can be determined from an X-ray CT image obtained with a resolution of 1.1 [μm]. Alternatively, in the case of powdered milk 1 with an average particle diameter of around 100-500 [μm], the average sphericity can be determined from an X-ray CT image obtained with a resolution of 3.3 [μm].

[0064] If powdered milk 1 is imaged with a resolution of less than 1 / 150th of its average particle size, the X-ray CT image may measure not only the overall shape of powdered milk 1 but also very microscopic surface roughness, potentially leading to errors. On the other hand, if powdered milk 1 is imaged with a resolution greater than 1 / 30th of its average particle size, it becomes impossible to accurately reproduce the shape of powdered milk 1 (the interface between gas and solid), so the polygon is expected to be simplified and the values ​​to shift. Therefore, a resolution of 1 / 150th or more and 1 / 30th or less is preferable.

[0065] (1-4) Density (particle density) The particle density ρ of powdered milk 1 is 1.16 [g / cm³]. ３ Preferably it is less than or equal to 1.15 [g / cm³]. ３ It is more preferable that the particle density ρ is less than or equal to 1.16 [g / cm³]. The particle density ρ is preferably measured using the particle density measuring device "AccuPic II 1345 (manufactured by Shimadzu Corporation)". The particle density ρ is the density including the internal voids of the milk powder 1. If the true density ρt is constant for the particles, the particle density ρ is a parameter that changes depending on the internal voids of the milk powder 1 and is an indicator that has a more direct effect on moldability (porosity and strength of solid milk). The milk powder 1 has a particle density ρ of 1.16 [g / cm³]. ３ By keeping it below ], good compression moldability can be achieved, and the particle density ρ is 1.15 [g / cm³]. ３By doing the following, even better compression moldability can be achieved.

[0066] The particle density ρ of powdered milk 1 is 1.08 [g / cm³]. ３ It is preferable that the concentration be 1.10 [g / cm³] or higher, and 1.10 [g / cm³] or higher. ３ It is more preferable that it be 1.14 [g / cm³] or more. ３ It is even more preferable that the particle density ρ is 1.08 [g / cm³]. ３ By setting the particle density to 1.10 [g / cm³] or higher, the strength of the particles can be ensured, and wear after solidification can be prevented. In addition, powdered milk 1 has a particle density ρ of 1.10 [g / cm³]. ３ Furthermore, 1.14 [g / cm³] ３ By doing so, the strength of the particles can be further ensured, and wear after solidification can be further prevented.

[0067] Based on the above, the average sphericity Φave of powdered milk 1 should be 0.66 or less, and the particle density ρ of powdered milk 1 should be 1.08 [g / cm³]. ３ ] or more 1.16 [g / cm ３ Furthermore, 1.08 [g / cm³] ３ ] or more 1.15 [g / cm ３ It is preferable that the average sphericity Φave of the milk powder 1 be 0.66 or less, and the particle density ρ of the milk powder 1 be 1.10 [g / cm³]. ３ ] or more 1.16 [g / cm ３ ] and furthermore, 1.10 [g / cm³ ３ ] or more 1.15 [g / cm ３ It is preferable that the average sphericity Φave of the milk powder 1 be 0.66 or less, and the particle density ρ of the milk powder 1 be 1.14 [g / cm³]. ３ ] or more 1.16 [g / cm ３ Furthermore, 1.14 [g / cm³] ３ ] or more 1.15 [g / cm ３ It is preferable to use the following values. For example, by adjusting the powdered milk 1 to any of the above numerical ranges, it is possible to produce a more preferable solid milk that has excellent compression molding properties when producing solid milk and possesses appropriate hardness and appropriate solubility.

[0068] (1-5) It is preferable that the uniformity of the uniform milk powder 1 is 0.60 or less. Uniformity is one of the values ​​that define the properties of particles, and the smaller the value, the more uniform the particle size is. By making the uniformity of the milk powder 1 0.60 or less, it is possible to produce solid milk that has excellent compression molding properties when manufacturing solid milk and possesses both appropriate hardness (strength) and appropriate porosity.

[0069] Furthermore, it is more preferable that the uniformity of the powdered milk 1 be 0.60 or less, preferably 0.55 or less, even more preferable 0.45 or less, and most preferably 0.40 or less. By ensuring uniform particle size, it is possible to produce solid milk with appropriate hardness (strength) and appropriate porosity.

[0070] The uniformity of powdered milk 1 is preferably 0.60 or less, more preferably 0.55 or less, even more preferably 0.45 or less, and most preferably 0.40 or less. By setting these values, it is possible to produce solid milk that has both appropriate hardness (strength) and appropriate porosity. Furthermore, the uniformity of powdered milk 1 is preferably 0.25 or higher, more preferably 0.30 or higher, and most preferably 0.40 or higher. By setting these values, the burden during manufacturing can be further reduced, such as by shortening the time required for granulation.

[0071] Based on the above, it is preferable that the powdered milk 1 has a uniformity of 0.25 or more and 0.6 or less, and more preferably 0.25 to 0.45. This is because it is excellent in terms of compression molding when manufacturing solid milk, and it is possible to manufacture solid milk that has an appropriate hardness (strength) and an appropriate porosity.

[0072] Furthermore, by ensuring that powdered milk 1 has a uniformity of 0.4 to 0.6, the burden during manufacturing can be reduced by shortening the granulation time and simplifying the classification and granulation equipment.

[0073] Uniformity can be calculated using the following method: (1-5-1) Subtract the particle size from the median diameter of the particle (the particle size value corresponding to 50% of the particle size distribution) to calculate the difference. (1-5-2) Calculate the value obtained by multiplying the absolute value of the difference calculated in "(1-5-1)" above by the frequency of that particle size in the particle size distribution. (1-5-3) After performing "(1-5-1)" and "(1-5-2)" above for each particle size obtained from the particle size distribution, calculate the sum of the values ​​of "(1-5-2)" for all particles. (1-5-4) Divide the value calculated in "(1-5-3)" above by the value obtained by multiplying the median diameter by the sum of the frequencies of each particle size distribution (usually 1). The value obtained in (1-5-4) is the uniformity. Particle size and frequency can be measured using known laser diffraction particle size distribution analyzers, etc.

[0074] (2) Method for producing powdered milk Next, the method for producing powdered milk 1 will be described. The powdered milk 1 according to this embodiment can be produced by a powdered milk production process, and the powdered milk production process preferably includes, for example, a liquid milk preparation process, a liquid milk clarification process, a sterilization process, a homogenization process, a concentration process, and a drying process. The liquid milk preparation process is a process for preparing liquid milk with the above-mentioned components. The liquid milk clarification process is a process for removing fine foreign matter contained in the liquid milk. To remove this foreign matter, for example, a centrifuge or a filter may be used.

[0075] The sterilization process is a process to kill bacteria and other microorganisms contained in the water and milk components of liquid milk. Since the microorganisms that are thought to be actually present vary depending on the type of liquid milk, the sterilization conditions (sterilization temperature and holding time) are set appropriately according to the microorganisms.

[0076] The homogenization process is a process for homogenizing liquid milk. Specifically, it reduces the particle size of solid components such as fat globules contained in the liquid milk and disperses them uniformly in the liquid milk. To reduce the particle size of the solid components in the liquid milk, for example, the liquid milk can be passed through narrow gaps while under pressure.

[0077] The concentration process is a process for concentrating liquid milk. For example, a vacuum evaporator or evaporator can be used to concentrate the liquid milk. The concentration conditions are set appropriately within a range that does not excessively alter the components of the liquid milk. This allows concentrated milk to be obtained from the liquid milk.

[0078] The drying process preferably includes a spray drying step in which liquid milk, which is the raw material for powdered milk 1, is spray-dried to obtain powdered milk 1. In the spray drying step, the liquid milk that is the raw material is sprayed, and the sprayed liquid milk is dried to obtain powdered milk 1. In addition, as a drying process that includes a spray drying step, for example, a foam drying step can also be used.

[0079] The foam drying process is a process for manufacturing powdered milk 1 according to the foam drying method. The foam drying method includes a gas dispersion step in which a predetermined gas is dispersed in the liquid milk that is the raw material. In the gas dispersion step, 1 × 10⁻¹⁶ of the volume of the liquid milk －２ It is preferable to disperse a predetermined gas in the liquid milk in an amount between twice and seven times the volume. Furthermore, in the gas dispersion step, the ratio of the volume flow rate of the predetermined gas to the liquid milk is 1 × 10⁻⁶. －２ It is preferable to flow the liquid milk along the flow path while maintaining a volume between twice and seven times its original volume. Furthermore, in the gas dispersion step, it is preferable to mix a predetermined gas with the liquid milk under pressurized conditions. The gas can be one or more gases selected from the group consisting of carbon dioxide, air, nitrogen, oxygen, and noble gases.

[0080] The foam drying method includes a spray drying step in which the liquid milk that has undergone the gas dispersion step described above is sprayed, and the sprayed liquid milk is dried to obtain powdered milk 1. In the spray drying step, the liquid milk that has had a predetermined gas dispersed in the gas dispersion step described above and is in a state where its density has been reduced is sprayed. Preferably, the spray drying step is performed continuously within a period of 0.1 seconds to 5 seconds after the completion of the gas dispersion step.

[0081] In the foam drying method, the gas dispersion step and the spray drying step are carried out continuously, and by adjusting the degree of gas dispersion in the liquid milk, the spraying conditions of the liquid milk, and the number of times the gas dispersion step and spray drying step are repeated, the average sphericity Φave of the powdered milk 1 can be adjusted to 0.66 or less by binding the fine particles together and drying them (drying step).

[0082] In the manufacturing method described above, after the concentration step, a drying step is performed in which the liquid milk, which is the raw material for powdered milk 1, is spray-dried to produce powdered milk 1 with an average sphericity of 0.66 or less. However, the present invention is not limited to this. In addition, powdered milk 1 can also be manufactured using a granulation step. When using a granulation step, a drying step may be performed after the concentration step, and then a granulation step may be performed after the drying step to produce powdered milk 1 with an average sphericity of 0.66 or less. Furthermore, in addition, the drying step and granulation step may be performed simultaneously in a process in which the drying step is performed after the concentration step, such as by spray drying, so that the drying step and granulation step are performed together without distinction, and powdered milk 1 with an average sphericity of 0.66 or less can be manufactured.

[0083] The granulation process is a process of binding powdered milk 1 together using a binder such as a liquid. The granulation process may utilize a spray dryer, extruder, agitator, fluidized bed granulator, fluidized bed granulator, rolling granulator, rolling fluidized bed granulator, dry granulator, etc. The fluidized bed granulation process is a process of manufacturing powdered milk 1 according to the fluidized bed granulation method. The fluidized bed granulation method involves introducing a gas such as heated air into a granulation tank, causing the particles to flow with the gas, and then spraying a liquid onto the fluidized particles to perform granulation. The fluidized bed granulation method can produce the desired powdered milk 1 by binding fine particles together with a liquid and then drying them.

[0084] In the fluidized bed granulation method, by adjusting the amount of heated air flowing into the granulation tank, the degree of gas dispersion among the fine particles, the liquid spraying conditions, and the rolling flow time, the average sphericity Φave of the powdered milk 1 can be adjusted to 0.66 or less by mixing the fine particles with water without using a binder, binding multiple fine particles together, and drying them (granulation process).

[0085] Then, solid milk can be produced by compressing and molding the powdered milk 1 manufactured in this manner (compression step).

[0086] By following the process described above, powdered milk 1 with an average sphericity Φave suitable for producing solid milk can be manufactured. The obtained powdered milk 1 is then compressed and molded to form a compressed molded product. The shape of the compressed molded product is determined by the shape of the die (die of the tablet press) used for compression molding, but is not particularly limited as long as it has a certain size (size, thickness, angle). The shapes of the compressed molded product can be cylindrical, elliptical, cubic, rectangular, plate-shaped, polygonal prism-shaped, conical, polygonal pyramidal, frustoconical, frustoconical, spherical, or polyhedral. From the viewpoint of ease of molding and ease of transportation, cylindrical, elliptical, and rectangular molded products are preferred. Next, the obtained powdered milk compressed molded product is subjected to a hardening treatment including humidification and drying to produce solid milk.

[0087] The solid milk produced by the above-described manufacturing method can, for example, have a tensile strength in the range of 90 kPa to 300 kPa. Furthermore, the solid milk produced by the above-described manufacturing method can, for example, have a porosity in the range of 30% to 50%.

[0088] (3) Verification Test (3-1) Relationship between Granulation Time and Sphericity Next, we investigated the relationship between granulation time and sphericity when producing powdered milk 1. Here, powdered milk 1 was produced using the fluidized bed granulation method according to the production method described above. Meiji FM-T (manufactured by Meiji Co., Ltd.) was used as the raw material for powdered milk 1.

[0089] In the fluidized bed granulation method, 800 g of fine particles to be used as raw material are placed into a rolling fluidized bed granulator (product name "Multiplex MP-01," manufactured by Powrec Co., Ltd.), the supply air temperature is set to room temperature of 25 °C, and 0.4 m of air is added. ３Air was blown in at [ / min]. In addition, in the rolling fluidized bed granulator, the rotor speed was set to 1000 [rpm], and water flow rate was 1.6 [g / min] and air was sprayed from a two-fluid nozzle at 36 [NL / min]. The granulation time for granulating the fine particles by spraying water was varied to 0 [min], 10 [min], 20 [min], and 30 [min], and after each granulation time, the mixture was dry-heat dried at an exhaust temperature of 98 [°C] to produce powdered milk consisting of particles for each granulation time. The drying time was adjusted to be equal to the moisture content of the original raw material (1.9 [%]) (within ±0.2 [%]).

[0090] Next, for each powdered milk produced with a different granulation time, the average sphericity Φave was calculated according to the average sphericity calculation process described in "(1-3) Average Sphericity" above. As a result, the results shown in 4A of Figure 4 were obtained.

[0091] As shown in Figure 4A, it was confirmed that increasing the granulation time decreased the average sphericity Φave and caused irregularities to form on the particle surface. Furthermore, it was confirmed that by setting the granulation time to 10 [min] or more, it was possible to produce powdered milk 1 with an average sphericity Φave of 0.66 or less.

[0092] (3-2) Relationship between the porosity of molded products and the tensile strength of molded products Next, a powdered milk with a granulation time of 0 [min] was designated as Comparative Example 1, a powdered milk with a granulation time of 10 [min] was designated as Example 1, a powdered milk with a granulation time of 20 [min] was designated as Example 2, and a powdered milk with a granulation time of 30 [min] was designated as Example 3. Compressed molded products (hereinafter simply referred to as molded products) that become solid milk were manufactured from each of these powdered milks, and the porosity and tensile strength of the molded products were investigated, and the results shown in 4B of Figure 4 were obtained.

[0093] The molded products were manufactured by compressing the powdered milk from Comparative Example 1 and Examples 1 to 3 under the following compression conditions. In this verification test, considering that the theoretical compression molding behavior may not be achieved depending on the design of the molded product, such as the corners, and that it is difficult to convert the strength of the obtained molded product into material mechanics properties (= strength), evaluation experiments were conducted using molded products compressed into cylindrical tablet shapes, which allow for strength conversion.

[0094] In this validation test, a tableting simulator (product name: Style'One (Medel Pharma)) was used to compress 0.694 g of powdered milk sample into a standard die with an inner diameter of 11.28 mm (compression area = 100 mm²). ２ The material was filled into a container and compressed at a compression speed of 10 mm / s. The thickness of the cylindrical tablet-shaped molded product was adjusted by adjusting the spacing between the punches, and the tensile strength of the obtained cylindrical tablet-shaped molded product was measured using a load cell type tablet hardness tester (portable checker PC-30 (manufactured by Okada Seikou Co., Ltd.)).

[0095] The circular base of a cylindrical tablet-shaped molded object was placed on a load cell type tablet hardness tester, and a fracture terminal was pressed against the circumferential surface of the molded object at a constant speed. The load [N] at which the molded object fractured was measured.

[0096] The force f [N] applied to the jig when a cylindrical tablet-shaped molded object is fractured by a load cell type tablet hardness tester can be converted to tensile strength σ using Airy's stress function as follows: Equation (2). Hereinafter, D represents the diameter [m] of the circular end face of the cylindrical tablet-shaped molded object, and t represents the axial height [m] of the cylindrical tablet-shaped molded object. The tensile strength σ for Comparative Example 1 and Examples 1 to 3 is shown on the vertical axis of 4B in Figure 4.

[0097]

[0098] The porosity was calculated as follows: Since it is not easy to determine the porosity by actually measuring the true density of powdered milk, a typical particle density of 1.12 [g / cm³] was used. ３ Using the following formula (3), the porosity ε was calculated for Comparative Example 1 and Examples 1-3, respectively. In this verification test, since all samples have the same composition, there is no major problem in keeping the calculated density constant. The porosity ε for Comparative Example 1 and Examples 1-3 is shown on the horizontal axis of 4B in Figure 4.

[0099]

[0100] A molded product can be said to have good solubility (ease of solubility in solvents such as water) if its porosity ε is high, and easy handling if its tensile strength σ is high. Ideally, both porosity ε and tensile strength σ should be high for a molded product. From the results of 4A and 4B in Figure 4, it was confirmed that the tensile strength σ increases as the average sphericity Φave decreases, and that the moldability of the molded product improves as the average sphericity Φave decreases. Here, improved moldability means that the tensile strength σ is higher even with the same porosity ε. Examples 1 to 3 showed improved tensile strength σ compared to Comparative Example 1, even with the same porosity ε, confirming that the moldability was improved compared to Comparative Example 1.

[0101] (3-3) Comparison with Existing Products Next, in the same manner as in the above-described examples, powdered milk 1 of Examples 4 to 11 was produced using the fluidized bed granulation method, and the average sphericity Φave of the obtained powdered milk 1 was measured. The results are shown in Figure 5A. Examples 4 to 11 were produced by granulating under different granulation conditions, and in all cases the average sphericity Φave was 0.66 or less. The uniformity was 0.4 to 0.6.

[0102] In this verification test, to confirm the moldability of molded products made from powdered milk, differences in density significantly affect moldability. Therefore, powdered milk with a density of 1.155 ± 0.01 [g / ml] was used as a sample. Similarly, since excessively high moisture content also affects moldability, powdered milk with a moisture content of 1 to 4.0 [wt%] was used as a sample. Regarding the composition, significant changes in the ratio of carbohydrates and fats also affect moldability. Therefore, powdered milk with carbohydrates of 50 to 58 [wt%] and lipids of 24 to 28 [wt%] was used as a sample.

[0103] Separately, we obtained 15 types of existing powdered milk products, which were designated as Comparative Examples 2 to 16.

[0104] Comparative Example 2 is Hagukumi (manufactured by Morinaga & Co.). Comparative Example 3 is HiQ comfort (manufactured by Nutricia). Comparative Example 4 is Meiji FM-T (manufactured by Meiji Co.). Comparative Example 5 is Anmun (manufactured by Fonterra). Comparative Examples 6 and 7 are Aptamil (manufactured by Danone). Comparative Example 8 is Kinryokan Chinho (manufactured by Ili Co.). Comparative Example 9 is Fubo Ruimo (manufactured by Synutra). Comparative Example 10 is Jingzhi (manufactured by Mengniu). Comparative Example 11 is NAN (manufactured by Nestlé). Comparative Example 12 is BELSOL (manufactured by Weiss). Comparative Example 13 is Frisolac (manufactured by Friesland Campina). Comparative Example 14 is Mead Johnson (manufactured by Mead Johnson). Comparative Example 15 is Nutrilon (manufactured by Nutricia). Comparative Example 16 is Hoshihiho (manufactured by Hishitsuru Co., Ltd.). Comparative Examples 2 to 16 are powdered milk with a density of 1.18 ± 0.03 [g / ml]. The moisture content is 1 to 4.0 [wt%]. The carbohydrate content in the formulation is 50 to 58 [wt%] and the lipid content is 24 to 28 [wt%]. Comparative Examples 2 to 16 are powdered milk of the same type as Examples 4 to 11.

[0105] Then, for Comparative Examples 2 to 16, the average sphericity Φave was calculated according to the average sphericity calculation process described in "(1-3) Average Sphericity" above. The results are shown in Figure 5, 5B. It was confirmed that all of Comparative Examples 2 to 16 had an average sphericity Φave of 0.67 or higher. From Figures 5, 5A and 5B, it can be seen that Comparative Examples 2 to 16, which are typical powdered milk, have an average sphericity Φave of 0.67 or higher, while Examples 4 to 11, which have an average sphericity Φave of 0.66 or lower, are unique powdered milk.

[0106] Next, using the same compression conditions as described in "(3-2) Relationship between the porosity of molded products and the tensile strength of molded products" above, the powdered milk of Examples 4-11 and Comparative Examples 2-16 was also compressed and molded to produce molded products. The porosity ε and tensile strength σ of each molded product of Examples 4-11 and Comparative Examples 2-16 were then examined, and the results shown in Figure 6 were obtained. The results for Examples 4-11 are shown by solid and dotted lines, and the results for Comparative Examples 2-16 are shown by dotted, dashed, and dashed lines.

[0107] Figure 6 shows the porosity ε on the horizontal axis and the tensile strength σ on the vertical axis. The porosity ε in Figure 6 was calculated based on equation (3) above, in the same manner as in Examples 1 to 3 described above. The tensile strength σ in Figure 6 was calculated based on equation (2) above, in the same manner as in Examples 1 to 3 described above.

[0108] From the results shown in Figure 5, which illustrates the calculation of the average sphericity Φave, and Figure 6, which illustrates the calculation of the porosity ε and tensile strength σ, it can be confirmed that Examples 4 to 11, with an average sphericity Φave of 0.66 or less, showed improved tensile strength σ compared to Comparative Examples 2 to 16, with an average sphericity Φave of 0.67 or more, even with the same porosity ε, indicating improved moldability compared to Comparative Examples 2 to 16.

[0109] (3-4) Relationship between average sphericity and moldability index Here, from the results in Figure 6, the moldability of powdered milk can be represented by a straight line with almost the same slope when the tensile strength σ is plotted on a logarithmic scale. Therefore, the experimental values ​​obtained from each sample were approximated by the least squares method using the following equation (4), and the moldability was evaluated using the moldability index Ic.

[0110] σ=Ic・exp(-11.11ε)...(4)

[0111] The moldability index Ic is an index using the Ryshkewitch-Duckworth equation (equation (5) below), which is commonly used to describe the relationship between the strength and void structure of brittle porous materials. k is a constant derived from experiments and represents the bonding capacity of the raw materials.

[0112] σ=Ic・exp(−kε)…(5)

[0113] The moldability index Ic represents the absolute value of the tensile strength σ relative to a moldability graph with nearly identical slopes, as shown in Figure 6. Here, while the moldability index Ic indicates moldability, it can also serve as a measure of the product's solubility (porosity) and manufacturability (strength) itself.

[0114] For example, if the porosity of solid milk falls below 30%, the solubility of the product decreases significantly. Furthermore, if the strength (tensile strength) of solid milk falls below 45 kPa, the product becomes unmanufacturable, making industrial production difficult. Therefore, the moldability index Ic is preferably 1.3 [MPa] or higher (tensile strength at 30% porosity is 46.4 kPa).

[0115] Figure 7 shows the relationship between the moldability index Ic and the average sphericity Φave calculated from the results in Figure 6. In Figure 7, the black circles in the area indicated by dots represent powdered milk 1 of Examples 4 to 11, where the average sphericity Φave is 0.66 or less. From the results in Figure 7, it is clear that powdered milk with a low average sphericity Φave has high moldability. It was confirmed that Examples 4 to 11 have improved moldability compared to Comparative Examples 2 to 16, which are typical powdered milk. Furthermore, from the results in Figure 7, it was confirmed that it is preferable for the average sphericity Φave to be 0.66 or less and the moldability index Ic to be 1.3 [MPa] or higher.

[0116] When the average sphericity Φave of powdered milk 1 is 0.66 or less, the moldability index Ic becomes 1.3 [MPa] or more, making it desirable for molding. Furthermore, when the average sphericity Φave is 0.59 or less, the moldability index Ic becomes 1.4 [MPa] or more, making it even more desirable for molding.

[0117] (4) Effects and Effects As described above, the powdered milk 1 according to this embodiment can provide powdered milk 1 with excellent moldability by having an average sphericity Φave of 0.66 or less. Furthermore, the powdered milk 1 has a particle density of 1.16 [g / cm³] ３ It is preferable that the following conditions are met, which further improves moldability.

[0118] Furthermore, the measurement method for measuring the average sphericity Φave of the powdered milk 1 according to this embodiment involves acquiring a three-dimensional image of each particle constituting the powdered milk 1 (image acquisition step), and creating a three-dimensional model of each particle constituting the powdered milk 1 based on the three-dimensional image (three-dimensional model creation step). After the three-dimensional model creation step, the average sphericity Φave of the powdered milk 1 is calculated from the three-dimensional model of each particle constituting the powdered milk 1 (average sphericity calculation step). Preferably, the method further includes a threshold correction step to adjust the binarization threshold and an internal void removal step to remove internal voids from particles in the binarized image generated based on the three-dimensional image, before the three-dimensional model creation step. This allows the measurement method for measuring the average sphericity Φave of the powdered milk 1 to perform shape analysis of the powdered milk 1, which is composed of fine particles. Furthermore, when performing the internal void removal step, it is desirable to perform a void volume correction step to adjust the maximum internal void volume v3, which serves as a reference when removing internal voids. This makes it possible to create a three-dimensional model that accurately reproduces the shape of each particle from the binarized image generated based on the three-dimensional image.

[0119] (5) Method for measuring the average sphericity of a powder The procedure for calculating the average sphericity in "(1-3) Average Sphericity" described above was explained using the example of measuring the average sphericity Φave of powdered milk 1, but the present invention is not limited to powdered milk. The powder used to measure the average sphericity Φave may be, for example, food powder, or powders of medicines, minerals, building materials, resins, etc. For embodiments of measuring the average sphericity Φave of powders other than powdered milk, simply replace "powdered milk" with "food powder" or "powder" in "(1-3) Average Sphericity" described above.

[0120] In addition to powdered milk, other food powders that can be used to measure the average sphericity Φave using the average sphericity calculation procedure include, for example, protein powders such as whey protein, soy protein, and collagen peptides, amino acid powders, and oil-containing powders such as MCT oil. Lactose or other carbohydrates may be added to the food powder as appropriate. In addition to lactose or other carbohydrates, nutrients such as fat, protein, minerals, and vitamins, as well as food additives, may be added to the food powder.

[0121] Furthermore, the protein powder in the above-mentioned food powder may be milk casein, meat powder, fish powder, egg powder, wheat protein, wheat protein hydrolysate, etc. These protein powders may be used individually or in combination of two or more.

[0122] Furthermore, the whey protein in the above-mentioned food powders refers to the general term for proteins in milk excluding casein. It may also be classified as whey protein. Whey protein is composed of multiple components such as lactoglobulin, lactalbumin, and lactoferrin. When milk or other dairy raw materials are adjusted to an acidic state, the protein that precipitates is casein, and the protein that does not precipitate is whey protein. Examples of powdered raw materials containing whey protein include WPC (whey protein concentrate, with a protein content of 75-85% by mass) and WPI (whey protein isolate, with a protein content of 85% by mass or more). These may be used individually or in combination of two or more.

[0123] Furthermore, the soy protein in the above-mentioned food powder can be any protein contained in soybeans, and may be extracted from soybeans. Alternatively, refined soy protein can be used. The refinement method is not particularly limited, and conventionally known methods can be used. As such soy protein, commercially available powders for food and beverages, medical use, and supplements can be used. These may be used individually or in combination of two or more types.

[0124] Furthermore, the amino acids contained in the above-mentioned food powder amino acid powder are not particularly limited, but for example, arginine, lysine, ornithine, phenylalanine, tyrosine, valine, methionine, leucine, isoleucine, tryptophan, histidine, proline, cysteine, glutamic acid, asparagine, aspartic acid, serine, glutamine, citrulline, creatine, methyllysine, acetyllysine, hydroxylysine, hydroxyproline, glycine, alanine, threonine, cystine, etc. may be used individually or in combination of two or more.

[0125] Furthermore, the amino acids contained in the above-mentioned food powder may be either natural or synthetic, and either a single amino acid or a mixture of multiple amino acids may be used. In addition, not only free amino acids, but also salts such as sodium salts, hydrochloride salts, and acetate salts, as well as derivatives such as carnitine and ornithine, may be used as amino acids.

[0126] In this specification, "amino acid" includes α-amino acids, β-amino acids, and γ-amino acids. Furthermore, amino acids may be either L-forms or D-forms.

[0127] Furthermore, the oils and fats contained in the oil-containing powder of the above-mentioned food powder include, in addition to the MCT oil mentioned above, animal fats and fats, vegetable fats and fats, fractions thereof, hydrogenated oils and transesterified oils. One or more of these may be added. Examples of animal fats and fats include milk fat, lard, beef tallow and fish oil. Examples of vegetable fats and fats include soybean oil, rapeseed oil, corn oil, coconut oil, palm oil, palm kernel oil, safflower oil, cottonseed oil, linseed oil and MCT (Medium Chain Triglyceride) oil.

[0128] Furthermore, the carbohydrates in the above-mentioned food powders include, in addition to the lactose mentioned above, oligosaccharides, monosaccharides, polysaccharides, and artificial sweeteners, etc. One or more of these may be added. Examples of oligosaccharides include lactose, sucrose, maltose, galactooligosaccharides, fructooligosaccharides, lactulose, etc. Examples of monosaccharides include glucose, fructose, and galactose, etc. Examples of polysaccharides include starch, soluble polysaccharides, and dextrin, etc.

[0129] Furthermore, sweeteners can be used as an example of food additives for the above-mentioned food powders. Any sweetener commonly used in food and pharmaceuticals can be used, and may be either natural or synthetic sweeteners. Sweeteners are not particularly limited, but include, for example, glucose, fructose, maltose, sucrose, oligosaccharides, sugar, granulated sugar, maple syrup, honey, molasses, trehalose, palatinose, maltitol, xylitol, sorbitol, glycerin, aspartame, advantame, neotame, sucralose, acesulfame potassium, and saccharin.

[0130] Furthermore, an example of a food additive for the above-mentioned food powder is an acidulant. Acidulants are not particularly limited, but include, for example, acetic acid, citric acid, anhydrous citric acid, adipic acid, succinic acid, lactic acid, malic acid, phosphoric acid, gluconic acid, tartaric acid, and salts thereof. Acidulants can suppress (mask) the bitterness caused by the type of amino acid.

[0131] Furthermore, the nutritional components of the above-mentioned food powder may include any components such as fat, protein, minerals, and vitamins.

[0132] Examples of fats include animal fats and oils, vegetable fats and oils, fractions thereof, hydrogenated oils, and transesterified oils. One or more of these may be added. Examples of animal fats and oils include milk fat, lard, beef tallow, and fish oil. Examples of vegetable fats and oils include soybean oil, rapeseed oil, corn oil, coconut oil, palm oil, palm kernel oil, safflower oil, cottonseed oil, linseed oil, and MCT (Medium Chain Triglyceride) oil.

[0133] Examples of proteins include milk protein and milk protein fractions, animal protein, plant protein, peptides and amino acids obtained by breaking down these proteins into various chain lengths using enzymes, etc. One or more of these may be added. Examples of milk protein include casein, whey protein (α-lactalbumin, β-lactoglobulin, etc.), whey protein concentrate (WPC), and whey protein isolate (WPI). Examples of animal protein include egg protein (egg powder), meat powder, and fish powder. Examples of plant protein include soy protein and wheat protein. Examples of peptides include collagen peptide. Examples of amino acids include taurine, cystine, cysteine, arginine, and glutamine. One or more of these may be added.

[0134] Minerals include iron, sodium, potassium, calcium, magnesium, phosphorus, chlorine, zinc, copper, and selenium. One or more of these may be added.

[0135] Examples of vitamins include vitamin A, vitamin D, vitamin E, vitamin K, vitamin B1, vitamin B2, vitamin B6, vitamin B12, vitamin C, niacin, folic acid, pantothenic acid, and biotin. One or more of these may be added.

[0136] Other food ingredients include, for example, cocoa powder, cacao powder, chocolate powder, microbial powders containing beneficial microorganisms such as lactic acid bacteria and bifidobacteria, milk fermentation component powders made from cultures obtained by adding microorganisms to milk and fermenting them, cheese powders made from cheese, functional food powders made from functional foods, and complete nutritional food powders made from complete nutritional foods. One or more of these may be added.

[0137] As described above, the measurement method for measuring the average sphericity Φave of a powder also involves acquiring a three-dimensional image of each particle constituting the powder (image acquisition step), and creating a three-dimensional model of each particle constituting the powder based on the three-dimensional image (three-dimensional model creation step). Furthermore, the measurement method for measuring the average sphericity Φave of a powder calculates the average sphericity Φave of the powder from the three-dimensional model of each particle constituting the powder (average sphericity calculation step). And, similar to the embodiment described above, it is desirable to further include a threshold correction step, an internal void removal step, and a void volume correction step before the three-dimensional model creation step. This allows the measurement method for measuring the average sphericity Φave of a powder to perform shape analysis of a powder composed of fine particles.

[0138] <Notes> (Note 1) Powdered milk having an average sphericity of 0.66 or less. The average sphericity is measured by a measurement method including the following steps (a) to (c): (a) Image acquisition step of acquiring a three-dimensional image of each particle constituting the powdered milk; (b) Three-dimensional model creation step of creating a three-dimensional model of each particle constituting the powdered milk based on the three-dimensional image; (c) Average sphericity calculation step of calculating the average sphericity of the powdered milk from the three-dimensional model of each particle constituting the powdered milk. (Note 2) Powdered milk as described in Note 1, used as a raw material for solid milk manufactured by compression molding. (Note 3) Average particle density of 1.16 [g / cm³] ３] The powdered milk described in Appendix 1 or 2 below. (Appendix 4) A method for producing solid milk, comprising a compression step of compressing and molding the powdered milk described in any one of Appendix 1 to 3. (Appendix 5) A method for producing solid milk described in Appendix 4, comprising a powdered milk manufacturing step of producing powdered milk before the compression step, wherein the powdered milk manufacturing step comprises a drying step of spray-drying liquid milk which is the raw material for the powdered milk. (Appendix 6) A method for producing solid milk described in Appendix 4, comprising a powdered milk manufacturing step of producing powdered milk before the compression step, wherein the powdered milk manufacturing step comprises a granulation step of mixing fine particles together to bind a plurality of fine particles together, and the powdered milk is produced by the granulation step. (Appendix 7) A method for producing solid milk described in Appendix 6, wherein in the granulation step, the powdered milk is produced by mixing the fine particles together and binding the plurality of fine particles together using a liquid. (Note 8) Solid milk manufactured by the manufacturing method described in any of Note 4 to 7, wherein the tensile strength is 90 [kPa] or more. (Note 9) Solid milk manufactured by the manufacturing method described in any of Note 4 to 7, wherein the porosity is 30 [%] or more. (Note 10) A method for measuring the average sphericity of a powder, comprising: an image acquisition step of acquiring a three-dimensional image of each particle constituting the powder; a three-dimensional model creation step of creating a three-dimensional model of each particle constituting the powder based on the three-dimensional image; and an average sphericity calculation step of calculating the average sphericity of the powder from the three-dimensional model of each particle constituting the powder. (Appendix 11) The method for measuring the average sphericity of a powder according to Appendix 11, further comprising an internal void removal step of removing internal voids of particles in a binarized image generated based on the three-dimensional image, wherein the three-dimensional model creation step creates the three-dimensional model from the binarized image generated based on the three-dimensional image.

[0139] 1. Powdered milk (powder)

Claims

1. Powdered milk having an average sphericity of 0.66 or less. The average sphericity is measured by a measurement method including the following steps (a) to (c): (a) an image acquisition step of acquiring a three-dimensional image of each particle constituting the powdered milk; (b) a three-dimensional model creation step of creating a three-dimensional model of each particle constituting the powdered milk based on the three-dimensional image; (c) an average sphericity calculation step of calculating the average sphericity of the powdered milk from the three-dimensional model of each particle constituting the powdered milk.

2. The powdered milk according to claim 1, used as a raw material for solid milk manufactured by compression molding.

3. The average particle density is 1.16 [g / cm³] ３ The powdered milk according to claim 1, wherein the powdered milk is as follows:

4. A method for producing solid milk, comprising a compression step of compressing and molding the powdered milk described in claim 1.

5. The method for producing solid milk according to claim 4, comprising a powder milk production step for producing powder milk prior to the compression step, wherein the powder milk production step includes a drying step for spray-drying liquid milk which is the raw material for the powder milk.

6. A method for producing solid milk according to claim 4, comprising a powder milk production step for producing powder milk prior to the compression step, wherein the powder milk production step includes a granulation step for mixing fine particles together to bind a plurality of fine particles together, and the granulation step for producing powder milk.

7. The method for producing solid milk according to claim 6, wherein in the granulation step, the fine particles are mixed together and the plurality of fine particles are bound together using a liquid to produce the powdered milk.

8. Solid milk produced by the manufacturing method described in any one of claims 4 to 7, wherein the tensile strength is 90 [kPa] or more.

9. Solid milk produced by the manufacturing method described in any one of claims 4 to 7, wherein the porosity is 30% or more.

10. A method for measuring the average sphericity of a powder, comprising: an image acquisition step of acquiring a three-dimensional image of each particle constituting the powder; a three-dimensional model creation step of creating a three-dimensional model of each particle constituting the powder based on the three-dimensional image; and an average sphericity calculation step of calculating the average sphericity of the powder from the three-dimensional model of each particle constituting the powder.

11. A method for measuring the average sphericity of a powder according to claim 10, further comprising an internal void removal step of removing internal voids of particles in a binarized image generated based on the three-dimensional image, wherein the three-dimensional model creation step creates the three-dimensional model from the binarized image generated based on the three-dimensional image.

Images