solid milk

Abstract

Provided are a solid food and solid milk having suitable solubility and manageable strength. In the solid food, which has a solid form obtained by compression molding of a food powder, the increase Ya in the (wt%) in the total crystallization rate, which is the difference between the crystal ratio relative to the entire weight of the solid food at a depth Xa (mm) from the surface and the crystal ratio of the interior of the solid food, satisfies expression (1A) below.　(1A) … Ya < -5.24Xa + 6.65

Description

[Technical Field]

[0001] The present invention relates to solid foods and solid milk. [Background technology]

[0002] Solid milk, which is obtained by compressing and molding powdered milk, is known as a solid food product (see Patent Documents 1 and 2). This solid milk is required to have solubility so that it dissolves quickly when placed in warm water, and also to be transportable, i.e., to have fracture resistance so that it does not break or crumble during transportation or carrying.

[0003] BACKGROUND ART A known tablet press for compressing and molding food powders such as powdered milk is one in which a slide plate having two die holes reciprocates horizontally (see Patent Document 3). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 5350799 [Patent Document 2] Patent No. 5688020 [Patent Document 3] Japanese Patent Application Laid-Open No. 2007-307592 Summary of the Invention [Problem to be solved by the invention]

[0005] There is a demand for solid foods and solid milks that are produced by compression molding food powders or powdered milk, and that have strength that makes them easy to handle, while also improving solubility.

[0006] An object of the present invention is to provide a solid food and solid milk that have suitable solubility and strength that is easy to handle. [Means for solving the problem]

[0007] The solid food of the present invention is a solid food product obtained by compression molding food powder, and the increase in total crystallization rate Ya (wt%), which is the difference between the ratio of crystals to the total weight at a depth Xa (mm) from the surface of the solid food and the ratio of crystals inside the solid food, satisfies the following formula (1A):

[0008] Ya<-5.24Xa+6.65 (1A)

[0009] The solid milk of the present invention is a solid milk obtained by compressing and molding powdered milk, and the increase in total crystallization rate Yb (wt%), which is the difference between the ratio of crystals to the total weight at a depth Xb (mm) from the surface of the solid milk and the ratio of crystals inside the solid milk, satisfies the following formula (1):

[0010] Yb<-5.24Xb+6.65 (1) [Effects of the Invention]

[0011] According to the present invention, a solid food product is produced by compression molding food powder, and the increase in total crystallinity Ya (wt%), which is the difference between the ratio of crystals to the total weight at a depth Xa (mm) from the surface of the solid food and the ratio of crystals inside the solid food, satisfies the following formula (1A): A solid food product whose increase in total crystallinity Ya (wt%) satisfies formula (1A) can be produced by subjecting a food powder compression molded product obtained by compression molding the food powder to a hardening treatment that includes a humidification treatment at a temperature of more than 100°C but not exceeding 330°C, for example, and can ensure easy-to-handle strength and achieve favorable solubility.

[0012] Ya<-5.24Xa+6.65 (1A)

[0013] Furthermore, according to the present invention, there is provided a solid milk obtained by compression-molding milk powder, in which the increase in total crystallinity Yb (wt%), which is the difference between the ratio of crystals to the total weight at a depth Xb (mm) from the surface of the solid milk and the ratio of crystals inside the solid milk, satisfies the following formula (1): Solid milk in which the increase in total crystallinity Yb (wt%) satisfies formula (1), can be produced by subjecting a compressed milk powder product obtained by compression-molding the milk powder to a hardening treatment that includes a humidification treatment at a temperature of more than 100°C and not more than 330°C, for example, and can ensure easy-to-handle strength and achieve suitable solubility.

[0014] Yb<-5.24Xb+6.65 (1) [Brief explanation of the drawings]

[0015] [Figure 1] FIG. 1 is a perspective view of solid milk according to a first embodiment. [Figure 2] FIG. 2 is a cross-sectional view of the solid milk taken along line X1-X2 of FIG. 1. [Figure 3] FIG. 2 is a cross-sectional view of the solid milk taken along line Y1-Y2 of FIG. 1. [Figure 4] FIG. 2 is an explanatory diagram illustrating the positions of the slide plate, upper punch, and lower punch of the tablet press. [Figure 5] FIG. 10 is an explanatory diagram illustrating the positions of the upper and lower punches at the start of the first compression. [Figure 6] FIG. 10 is an explanatory diagram illustrating the positions of the upper and lower punches after the first compression is completed and the second compression is started. [Figure 7] 1 is a graph showing the increase Y in the total crystallization rate (increase relative to the center) versus the depth X (mm) from the surface of solid milk according to an example. DETAILED DESCRIPTION OF THE INVENTION

[0016] Hereinafter, embodiments of the present invention will be described. However, the embodiments described below are merely examples and can be appropriately modified within the scope obvious to those skilled in the art.

[0017] First Embodiment (Composition of solid milk 10S) Fig. 1 is a perspective view of solid milk 10S according to this embodiment. Fig. 2 is a cross-sectional view of solid milk 10S taken along line X1-X2 in Fig. 1. Fig. 3 is a cross-sectional view of solid milk 10S taken along line Y1-Y2 in Fig. 1.

[0018] The solid milk 10S has a solid body 10 obtained by compression-molding powdered milk. The body 10 has a first surface 10A that is flat and parallel to the XY plane, and a second surface 10B that is flat and parallel to the XY plane. The first surface 10A and the second surface 10B are back-to-back surfaces. The shape of the body 10 is determined by the shape of the mold (the mortar of the tablet press) used for compression molding, but is not particularly limited as long as it has a certain degree of dimensions (size, thickness, angle). The general shape of the body 10 is a cylinder, an elliptical cylinder, a cube, a rectangular parallelepiped, a plate, a polygonal pillar, a polygonal truncated pyramid, a polyhedron, or the like. From the viewpoints of ease of molding and convenient transportation, a cylinder, an elliptical cylinder, and a rectangular parallelepiped are preferred. The main body 10 of the solid milk 10S shown in Figures 1 to 3 has a schematic shape of a rectangular parallelepiped with dimensions a x b x c (see Figure 1), and the main body 10 has side surfaces 10C parallel to the XZ plane or the YZ plane. The corners formed by the first surface 10A and the side surfaces 10C and the corners formed by the second surface 10B and the side surfaces 10C may each be chamfered to form a tapered shape. If the corners are chamfered, it is possible to prevent the solid milk 10S from breaking during transportation, etc.

[0019] The surface is the surface that forms the outside of a substance. The surface layer is a layer near the surface, including the surface. For example, the surface layer is a layer formed by compression molding of powdered milk and then hardened by hardening treatment. The surface layer in this embodiment is harder than the interior. Here, the surface layer being harder than the interior means that the force required to separate only the surface layer is relatively greater than the force required to separate the interior.

[0020] The solid milk 10S of this embodiment is solid milk obtained by compression molding and hardening powdered milk. Here, the increase in total crystallization rate Yb (wt%), which is the difference between the ratio of crystals to the total weight at a depth Xb (mm) from the surface of the solid milk 10S and the ratio of crystals inside the solid milk, satisfies the following formula (1):

[0021] Yb<-5.24Xb+6.65 (1)

[0022] The total crystallization rate is the ratio (wt%) of crystals to the total weight. The increase in the total crystallization rate is defined as the difference obtained by subtracting the crystallization rate of the crystals that were present before the hardening treatment from the crystallization rate of the crystals that increased in accordance with the magnitude of the influence of humidification during the hardening treatment. The crystallization rate of the crystals that were present before the hardening treatment corresponds to the crystallization rate of the crystals inside the solid milk that are not or substantially not affected by humidification during the hardening treatment in this embodiment. In other words, the increase in the total crystallization rate is the difference between the ratio of crystals to the total weight at each depth from the surface of the solid milk and the ratio of crystals inside the solid milk. Examples of the above crystals include α-lactose crystals and β-lactose crystals.

[0023] The "interior" of the solid milk refers to a region in which the total crystallinity rate does not change or does not substantially change before and after the hardening treatment, such as the central portion or a portion near the center of the solid milk. Specifically, it is a cubic range of ±1 mm in the X, Y, and Z directions from the center of the solid milk, or a spherical range with a radius of 1 mm from the center of the solid milk. The hardening treatment, which will be described in detail later, is a treatment carried out to harden the compressed milk powder product when producing solid milk.

[0024] The interior of the solid milk is described above as referring to a region where the total crystallinity rate does not change or does not substantially change before and after the hardening treatment, for example, the central part or the part near the center of the solid milk. However, it may simply be the central part or the part near the center of the solid milk, regardless of whether the total crystallinity rate changes before and after the hardening treatment.

[0025] In the solid milk 10S of this embodiment, the increase Yb (wt %) in the total crystallization rate at a depth Xb (mm) from the surface of the solid milk preferably satisfies the following formula (1-1).

[0026] Yb<-5.24Xb+6.15 (1-1)

[0027] The increase in the total crystallinity Yb (wt %) more preferably satisfies the following formula (1-2).

[0028] Yb<-5.24Xb+5.65 (1-2)

[0029] In the solid milk 10S of this embodiment, the increase Yb (wt %) in the total crystallization rate at a depth Xb (mm) from the surface of the solid milk preferably satisfies the following formula (2).

[0030] Yb≦6.34Xb 2 -11.15Xb+5.05 (2)

[0031] The increase in the total crystallinity Yb (wt %) more preferably satisfies the following formula (2-1).

[0032] Yb≦4.89Xb 2 -8.39Xb+3.51 (2-1)

[0033] The increase in the total crystallinity Yb (wt %) more preferably satisfies the following formula (2-2).

[0034] Yb≦6.40Xb 2 -7.59Xb+2.28 (2-2)

[0035] The increase in total crystallinity can be determined by, for example, XRD (X-ray diffraction) by cutting a 0.1 mm thick section from the surface of the sample for each XRD measurement, and calculating the total crystallinity of the entire surface. Furthermore, an XRD measurement device capable of two-dimensional mapping can measure the increase in total crystallinity in the depth direction of the sample with an accuracy of, for example, 0.05 mm to 0.1 mm.

[0036] The main body 10 may have one or more holes penetrating the main body 10 from the first surface 10A to the second surface 10B. The shape of the holes may be, for example, an oval, rounded rectangle, ellipse, circle, rectangle, square, or other polygonal shape in a cross section parallel to the XY plane. The holes are preferably positioned so that there is no significant deviation when viewed from the center of the first surface 10A. For example, the holes may be arranged point-symmetrically with respect to the center of the first surface 10A, or line-symmetrically with respect to a line parallel to the X axis or the Y axis passing through the center of the first surface 10A. When a hole is provided, the hole may have a tapered, inclined surface. Note that when a hole is provided, the inner wall surface of the hole is a surface that is harder than the interior, similar to the first surface 10A.

[0037] The components of solid milk 10S are basically the same as those of the raw material, powdered milk, such as fat, protein, carbohydrates, minerals, vitamins, and water.

[0038] Powdered milk is produced from liquid milk (liquid milk) containing milk components (e.g., components of cow's milk). Milk components include, for example, raw milk (full-fat milk), skim milk, and cream. The water content of liquid milk is, for example, 40% to 95% by weight. The water content of powdered milk is, for example, 1% to 5% by weight. The powdered milk may contain added nutritional components, as described below. The powdered milk may be whole milk powder, skim milk powder, or creamy powder, as long as it is suitable for producing solid milk 10S. The fat content of powdered milk is preferably, for example, 5% to 70% by weight.

[0039] The milk components used as raw materials for the above-mentioned milk powder are derived from, for example, raw milk. Specifically, they are derived from raw milk of cows (Holstein, Jersey, and other breeds), goats, sheep, buffalo, etc. The above-mentioned raw milk contains fat, but it may also be milk with an adjusted fat content in which part or all of the fat has been removed by centrifugation or the like.

[0040] Furthermore, the milk components used as raw materials for the above-mentioned milk powder are, for example, plant-derived milks. Specifically, these include soy milk, rice milk, coconut milk, almond milk, hemp milk, peanut milk, etc. Although the above-mentioned plant-derived milks contain fat, they may also be milks with an adjusted fat content in which some or all of the fat has been removed by centrifugation or the like.

[0041] The nutritional components that are the raw materials for the powdered milk are, for example, fat, protein, sugar, minerals, vitamins, etc. One or more of these may be added.

[0042] Proteins that can be used as raw materials for the above-mentioned milk powder include, for example, milk proteins and milk protein fractions, animal proteins, vegetable proteins, peptides obtained by decomposing these proteins into various chain lengths using enzymes or the like, and amino acids. One or more of these may be added. Examples of milk proteins include casein, whey proteins (α-lactalbumin, β-lactoglobulin, etc.), whey protein concentrate (WPC), and whey protein isolate (WPI). Examples of animal proteins include egg protein. Examples of vegetable proteins include soy protein and wheat protein. Examples of amino acids include taurine, cystine, cysteine, arginine, and glutamine.

[0043] The fats (oils) that can be used as raw materials for the above-mentioned milk powder include animal fats, vegetable fats, their fractionated oils, hydrogenated oils, and interesterified oils. One or more of these may be added. Animal fats include, for example, milk fat, lard, beef tallow, and fish oil. Vegetable fats include, 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.

[0044] Examples of carbohydrates that can be used as raw materials for the above-mentioned milk powder include oligosaccharides, monosaccharides, polysaccharides, and artificial sweeteners. One or more of these may be added. Oligosaccharides include lactose, sucrose, maltose, galactooligosaccharides, fructooligosaccharides, lactulose, and the like. Monosaccharides include glucose, fructose, and galactose, and the like. Polysaccharides include starch, soluble polysaccharides, and dextrin, and the like. Note that non-carbohydrate artificial sweeteners may be used instead of or in addition to carbohydrate artificial sweeteners.

[0045] Minerals that can be used as raw materials for the above-mentioned powdered milk include, for example, sodium, potassium, calcium, magnesium, iron, copper, and zinc. One or more of these may be added. Note that one or both of phosphorus and chlorine may be used instead of or in addition to the minerals sodium, potassium, calcium, magnesium, iron, copper, and zinc.

[0046] The solid milk 10S has many voids (e.g., pores) that are generated when the powdered milk, which is the raw material of the solid milk 10S, is compression-molded. These voids are dispersed (distributed) in accordance with the packing rate profile in the depth direction of the solid milk 10S. The larger (wider) the voids are, the easier it is for solvents such as water to penetrate, allowing the solid milk 10S to dissolve more quickly. On the other hand, if the voids are too large, the hardness of the solid milk 10S may decrease or the surface of the solid milk 10S may become rough. The dimension (size) of each void is, for example, 10 μm to 500 μm.

[0047] The solid milk 10S must have a certain degree of solubility in a solvent such as water. The solubility can be evaluated, for example, by preparing the solid milk 10S as a solute and water as a solvent to a predetermined concentration, and measuring the time it takes for the solid milk 10S to completely dissolve or the amount of solid milk remaining undissolved after a predetermined time.

[0048] The solid milk 10S preferably has a hardness within a predetermined range. Hardness can be measured by a known method. In this specification, hardness is measured using a load cell tablet hardness tester. The rectangular solid milk 10S is placed on the load cell tablet hardness tester with the second surface 10B as the bottom surface, and is fixed using one surface of the side surface 10C parallel to the XZ plane and one surface parallel to the YZ plane. The breaking terminal of the hardness tester is pressed at a constant speed from the other surface of the side surface 10C parallel to the XZ plane in the minor axis direction of the first surface 10A (the Y axis direction in FIG. 1 ) in a direction in which the YZ plane forms the fracture surface, and the load [N] at which the solid milk 10S breaks is defined as the hardness (tablet hardness) [N] of the solid milk 10S. In the case of solid milk 10S, the measurement point is selected from a point equidistant from the first surface 10A and the second surface 10B on a line segment where a plane parallel to the YZ plane, which is equidistant from a pair of YZ planes of the side surface 10C, intersects with the XZ plane of the side surface 10C. For example, a load cell tablet hardness tester (Portable Checker PC-30) manufactured by Okada Seiko Co., Ltd. is used. The breaker terminal incorporated in the hardness tester has a contact surface that contacts the solid milk 10S. The contact surface of the breaker terminal is a rectangle measuring 1 mm x 24 mm, and is oriented with the long axis of the rectangle parallel to the Z axis. At least a portion of the contact surface of the breaker terminal is configured to press against the measurement point of the solid milk 10S. The breaker terminal presses the solid milk 10S at a speed of 0.5 mm / s. The above hardness measurement is not limited to solid milk 10S, but can also be applied to measuring the hardness of a compressed milk powder product (unhardened solid milk 10S) described below. Regarding the hardness measured as described above, in order to minimize the risk of the solid milk 10S breaking during transportation, etc., the hardness of the solid milk 10S is preferably 20 N or more, more preferably 40 N or more. On the other hand, if the hardness of the solid milk 10S is too high, the solubility of the solid milk 10S will decrease, so the hardness of the solid milk 10S is preferably 100 N or less, more preferably 70 N or less.

[0049] The hardness used here is a physical quantity of force with units of [N (Newton)]. The larger the fracture cross-sectional area of ​​the solid milk sample, the greater the hardness. Here, "fracture" refers to breakage when a static vertical load is applied to a sample such as solid milk 10S, and the cross-sectional area created when this breakage occurs is called the "fracture cross-sectional area." In other words, hardness [N] is a physical quantity that depends on the dimensions of the solid milk sample. The breaking stress [N / m 2 ]. The breaking stress is the force applied per unit breaking area at the time of breaking, and is an index that does not depend on the dimensions of the solid milk sample, and can be used to compare the mechanical action on solid milk samples even between solid milk samples of different dimensions. Breaking stress = hardness / breaking area. In this specification, hardness [N] is sometimes used for simplicity, but these are breaking stress [N / m 2 ]. When calculating the breaking stress, a fracture surface is assumed and the minimum fracture cross-sectional area of ​​the assumed fracture surface is used for the calculation. For example, in the case of solid milk 10S, the ideal fracture cross-sectional area is expressed as the dimensions b x c, which is the fracture cross-sectional area on a plane that passes through the center of the solid milk and includes a line parallel to the Z axis. For example, if the approximate dimensions of the shape of solid milk 10S are a rectangular parallelepiped with dimensions of 31 mm (a) x 24 mm (b) x 12.5 mm (c), the ideal fracture cross-sectional area is 300 mm 2 (24mm(b) x 12.5mm(c)). The preferred hardness range of 20N to 100N for the solid milk 10S is determined by the hardness of the rupture cross section (300mm 2 ) to get 0.067N / mm 2 More than 0.33N / mm 2 For example, the preferred range of breaking stress for solid milk 10S is 0.067 N / mm 2 or less, taking into account the range of breaking cross-sectional area. 2 More than 0.739N / mm 2 The following is the result.

[0050] (Solid Milk 10S Manufacturing Method) Next, a method for producing solid milk 10S will be described. First, milk powder, which is the raw material for solid milk 10S, is produced. In the milk powder production process, milk powder is produced through, for example, a liquid milk preparation process, a liquid milk clarification process, a sterilization process, a homogenization process, a concentration process, a gas dispersion process, and a spray drying process.

[0051] The liquid milk preparation step is a step of preparing liquid milk from the above ingredients.

[0052] The clarification step is a step for removing minute foreign matter contained in the liquid milk, which can be removed using, for example, a centrifuge or a filter.

[0053] The sterilization process is a process for killing microorganisms such as bacteria contained in the water, milk components, etc. of liquid milk. Since the microorganisms that are actually thought to be contained vary depending on the type of liquid milk, the sterilization conditions (sterilization temperature and holding time) are set appropriately depending on the microorganisms.

[0054] The homogenization process is a process for homogenizing liquid milk. Specifically, the particle size of solid components such as fat globules contained in the liquid milk is reduced and they are uniformly dispersed in the liquid milk. In order to reduce the particle size of the solid components in the liquid milk, for example, the liquid milk may be passed through a narrow gap while being pressurized.

[0055] The concentration step is a step for concentrating liquid milk prior to the spray-drying step described below. Liquid milk can be concentrated using, for example, a vacuum evaporator or an evaporator. The concentration conditions are appropriately set 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. Subsequently, in the present invention, it is preferable to disperse a gas in the concentrated liquid milk (concentrated milk) and spray-dry it. The moisture content of the concentrated milk is, for example, 35% to 60% by weight, preferably 40% to 60% by weight, and more preferably 40% to 55% by weight. When such concentrated milk is used and a gas is dispersed therein, the density of the concentrated milk is reduced and the bulk is increased. By spray-drying the concentrated milk in this bulky state, powdered milk with desirable properties can be obtained when producing solid milk. This step may be omitted when the liquid milk has a low moisture content or when the amount of liquid milk to be processed in the spray-drying step is small.

[0056] The gas dispersion step is a step for dispersing a predetermined gas into the liquid milk. At this time, the predetermined gas may be, for example, 1×10 of the volume of the liquid milk. -2 The volume of the liquid milk is preferably 1×10 to 7 times the volume of the liquid milk. -2 The volume is preferably 1×10 to 5 times the volume of the liquid milk. -2 1×10 to 4×10, and most preferably 1×10 -2 It is more than double but less than three times.

[0057] In order to disperse the predetermined gas into the liquid milk, it is preferable to pressurize the predetermined gas. The pressure at which the predetermined gas is pressurized is not particularly limited as long as it is within a range that allows the gas to be effectively dispersed into the liquid milk, but examples of the pressure of the predetermined gas include 1.5 to 10 atmospheres, and preferably 2 to 5 atmospheres. Since the liquid milk is sprayed in the spray drying step described below, it flows along a predetermined flow path, and in this gas dispersion step, the pressurized predetermined gas is flowed into this flow path to disperse (mix) the gas into the liquid milk. In this way, the predetermined gas can be easily and reliably dispersed into the liquid milk.

[0058] In this way, the density of the liquid milk decreases and the apparent volume (bulk) increases by undergoing the gas dispersion process. The density of the liquid milk may be calculated by dividing the weight of the liquid milk by the total volume of the liquid milk in both the liquid and foamed states. Alternatively, the density may be measured using a density measuring device according to the bulk density measurement method (pigment: JISK5101) in accordance with the JIS method.

[0059] Therefore, the liquid milk in which the predetermined gas is dispersed flows through the flow path. Here, it is preferable that the volumetric flow rate of the liquid milk in the flow path is controlled to be constant.

[0060] In this embodiment, carbon dioxide (carbon dioxide gas) can be used as the predetermined gas. In the flow path, the ratio of the volumetric flow rate of carbon dioxide to the volumetric flow rate of liquid milk (hereinafter, this percentage is also referred to as the "CO2 mixing ratio [%]") can be, for example, 1% to 700%, preferably 2% to 300%, more preferably 3% to 100%, and most preferably 5% to 45%. By controlling the volumetric flow rate of carbon dioxide to be constant relative to the volumetric flow rate of liquid milk in this way, the uniformity of the milk powder produced therefrom can be improved. However, if the CO2 mixing ratio is too high, the proportion of liquid milk flowing through the flow path decreases, resulting in a decrease in the efficiency of milk powder production. Therefore, the upper limit of the CO2 mixing ratio is preferably 700%. The pressure at which carbon dioxide is pressurized is not particularly limited as long as it is within a range that allows carbon dioxide to be effectively dispersed into liquid milk. However, the carbon dioxide pressure can be, for example, 1.5 to 10 atmospheres, preferably 2 to 5 atmospheres. Furthermore, by continuously mixing carbon dioxide and liquid milk in a closed system (in-line), it is possible to reliably prevent the introduction of bacteria and other contaminants, thereby improving the hygiene of the powdered milk (or maintaining a high level of cleanliness).

[0061] In this embodiment, the predetermined gas used in the gas dispersion step is carbon dioxide (carbon dioxide). Instead of or in addition to carbon dioxide, one or more gases selected from the group consisting of air, nitrogen (N2), and oxygen (O2), or a rare gas (e.g., argon (Ar) or helium (He)) may be used. Since various gases are available, the gas dispersion step can be easily performed by using a readily available gas. Using an inert gas such as nitrogen or a rare gas in the gas dispersion step is preferable because it does not react with the nutritional components of the liquid milk, and therefore is less likely to deteriorate the liquid milk than air or oxygen. In this case, the ratio of the volumetric flow rate of the gas to the volumetric flow rate of the liquid milk can be, for example, 1% to 700%; preferably 1% to 500%; more preferably 1% to 400%; and most preferably 1% to 300%. For example, Bell et al. (RW BELL, FP HANRAHAN, BH WEBB: "FOAM SPRAY DRYING METHODS OF MAKING READILY DISPERSIBLE NONFAT DRY MILK", J. Dairy Sci, 46 (12) 1963, pp. 1352-1356) state that in order to obtain skim milk powder, they sprayed in air in an amount about 18.7 times the volume of nonfat milk. In the present invention, by dispersing a gas within the above range, it is possible to obtain powdered milk having properties suitable for producing solid milk. However, in order to reliably lower the density of liquid milk as a result of dispersing a predetermined gas in liquid milk in the gas dispersion step, it is preferable to use a gas that is easily dispersed in liquid milk or that is easily dissolved in liquid milk as the predetermined gas. For this reason, it is preferable to use a gas that has high solubility in water (water solubility), and the gas should be dispersed in water at a rate of 1 cm3 of water at 20°C and 1 atmosphere. 3 The solubility in 3A gas that satisfies the above conditions is preferred. Note that carbon dioxide is not limited to a gas, and may be dry ice or a mixture of dry ice and a gas. That is, in the gas dispersion step, a solid may be used as long as it can disperse a predetermined gas into liquid milk. By using dry ice in the gas dispersion step, carbon dioxide can be rapidly dispersed into cooled liquid milk, and as a result, milk powder having properties suitable for producing solid milk can be obtained.

[0062] The spray drying process is a process for evaporating water from liquid milk to obtain powdered milk (food powder). The powdered milk obtained in this spray drying process is obtained through a gas dispersion process and a spray drying process. This powdered milk is bulkier than powdered milk obtained without the gas dispersion process. The volume of the former is preferably 1.01 to 10 times that of the latter, but may also be 1.02 to 10 times, or 1.03 to 9 times.

[0063] In the spray-drying step, a predetermined gas is dispersed in the liquid milk in the gas dispersion step, and the liquid milk is spray-dried while its density is reduced. Specifically, it is preferable to perform spray-drying in a state in which the volume of the liquid milk after gas dispersion is 1.05 to 3 times, preferably 1.1 to 2 times, the volume of the liquid milk before gas dispersion. In other words, the spray-drying step is performed after the gas dispersion step is completed. However, the liquid milk is not in a uniform state immediately after the gas dispersion step is completed. For this reason, the spray-drying step is performed 0.1 to 5 seconds, preferably 0.5 to 3 seconds, after the gas dispersion step is completed. In other words, it is sufficient that the gas dispersion step and the spray-drying step are continuous. In this way, liquid milk is continuously fed into a gas dispersion device, the gas is dispersed, and the liquid milk with the gas dispersed therein is continuously supplied to the spray-drying device, where it can be continuously spray-dried.

[0064] A spray dryer can be used to evaporate the water content. The spray dryer includes a flow path for flowing the liquid milk, a pressure pump that pressurizes the liquid milk to flow along the flow path, a drying chamber that is wider than the flow path and is connected to the opening of the flow path, and a spraying device (nozzle, atomizer, etc.) installed at the opening of the flow path. The spray dryer uses the pressure pump to send the liquid milk along the flow path toward the drying chamber at the volumetric flow rate described above. Near the opening of the flow path, the spraying device disperses the concentrated milk into the drying chamber, and the liquid milk in a droplet (atomized) state is dried at high temperatures (e.g., hot air) in the drying chamber. In other words, by drying the liquid milk in the drying chamber, the water content is removed, and the concentrated milk becomes a powdered solid, i.e., milk powder. By appropriately setting the drying conditions in the drying chamber, the moisture content of the milk powder can be adjusted to make the milk powder less likely to aggregate. In addition, by using a spray device, the surface area per unit volume of droplets is increased, improving the drying efficiency and at the same time adjusting the particle size of the powdered milk.

[0065] By going through the steps described above, powdered milk suitable for producing solid milk can be produced.

[0066] The powdered milk obtained as described above is compression molded to form a compressed powdered milk product. Next, the obtained compressed powdered milk product is subjected to a hardening treatment including, for example, a humidifying treatment and a drying treatment. In this manner, solid milk 10S can be produced.

[0067] In the process of compressing and molding powdered milk, a compression means is used. The compression means is, for example, a pressure molding machine such as a tablet press or a compression test device. The tablet press is a device equipped with a mortar that serves as a mold for putting powdered milk into and a pestle that can be struck against the mortar. The compression molding process using a tablet press will be described below.

[0068] Figure 4 is an explanatory diagram illustrating the positions of the slide plate, upper punch, and lower punch of a tablet press. In the molding zone of the tablet press, a lower punch 31 is arranged below a die 30A of the slide plate 30 so as to be movable up and down by an actuator. Furthermore, an upper punch 32 is arranged above a die 30A of the slide plate 30 so as to be movable up and down by an actuator. Figure 4 shows the position where the lower punch 31 and the upper punch 32 are inserted into the die 30A of the slide plate 30 and are closest to each other. At this position, the distance between the lower punch 31 and the upper punch 32 is the final punch spacing L. The inner wall surface of the die 30A of the slide plate 30, the upper end surface of the lower punch 31, and the lower end surface of the upper punch 32 form the mold for compression molding. For example, by supplying powdered milk into a recess formed by the inner wall surface of the mortar 30A of the slide plate 30 and the upper surface of the lower punch 31, and then striking the upper punch 32 from above the mortar 30A, compression pressure is applied to the powdered milk, and the powdered milk is compressed and molded in the space SP surrounded by the inner wall surface of the mortar 30A of the slide plate 30, the upper end surface of the lower punch 31, and the lower end surface of the upper punch 32, and a compressed and molded powdered milk product is obtained.

[0069] The actuator that drives the lower punch 31 and the upper punch 32 up and down is, for example, a servo motor. In this embodiment, the compression speed during compression molding, i.e., the movement speed of the lower punch 31 and the upper punch 32, can be changed by changing the speed of the servo motor that serves as the actuator, as will be described in detail below. The actuator is not limited to a servo motor, and the method for changing the movement speed of the lower punch 31 and the upper punch 32 is not limited to this. For example, a hydraulic cylinder or the like may be used. Furthermore, during compression molding, the lower punch 31 and the upper punch 32 may be moved in a direction approaching each other, or one may be fixed and the other may be moved alone.

[0070] The following describes a process of compression molding by changing the compression speed during compression molding, i.e., the moving speed of the lower punch 31 and the upper punch 32. During this compression molding, the compression speed at which the upper end surface of the lower punch 31 and the lower end surface of the upper punch 32 approach each other is changed (switched). That is, first, a first compression is performed at a first compression speed V1, and then, following this first compression, a second compression is performed at a second compression speed V2. In this embodiment, the second compression speed V2 is set slower than the first compression speed V1.

[0071] In this example, the compression distances of the first and second compressions are based on the state at the end of the second compression, i.e., the end of the entire compression process, as shown in Figure 4. Compression by the lower punch 31 and the upper punch 32 is continued until the punch distance between the upper end surface of the lower punch 31 and the lower end surface of the upper punch 32 becomes the final punch distance L. The final punch distance L is the final thickness of the compressed milk powder product compressed in the entire compression process. This final punch distance L is determined taking into account the expansion of the compressed milk powder product when compression is released, and has a value smaller than or equal to the target thickness of the compressed milk powder product.

[0072] The tablet press of the embodiment controls the compressed product to be in close contact with both surfaces of the lower punch 31 and the upper punch 32 during switching between the first and second compressions, and does not release the pressure on the compressed product. On the other hand, conventionally known tablet presses (for example, the tablet press described in JP 2008-290145 A) apply a pre-pressure to remove air from the compressed product, then release the pressure once, and then apply the main pressure to form the compressed product. Unlike conventional tablet presses, the tablet press of the embodiment does not release the pressure between the first and second compressions, and compresses the compressed product by bringing both surfaces of the lower punch 31 and the upper punch 32 into close contact with the compressed product, making it possible to impart sufficient hardness to the compressed product.

[0073] Fig. 5 shows the positions of the lower punch 31 and the upper punch 32 at the start of the first compression. Fig. 6 shows the positions of the lower punch 31 and the upper punch 32 after the first compression is completed and the second compression is initiated. The compression from the punch spacing (L+L1+L2) shown in Fig. 5 to the punch spacing (L+L2) shown in Fig. 6 is the first compression. The compression from the punch spacing (L+L2) shown in Fig. 6 to the final punch spacing L shown in Fig. 4 is the second compression.

[0074] The first compression distance L1 of the first compression is the distance by which the punch spacing decreases during the first compression. The second compression distance L2 of the second compression is the distance by which the punch spacing decreases during the second compression. Since the second compression is performed immediately after the first compression without releasing the compression, this second compression distance L2 is the compression distance from the punch spacing compressed during the first compression (L+L2) to the final punch spacing (L).

[0075] The rate of change of the punch spacing in the first compression is the first compression speed V1, and the rate of change of the punch spacing in the second compression is the second compression speed V2. Note that if the rate of change of the punch spacing varies during the first compression and the second compression, the average speeds are taken as the first compression speed V1 and the second compression speed V2.

[0076] By performing the second compression at a second compression speed V2 slower than the first compression speed V1 after the first compression, the hardness of the compressed and molded powder milk product can be increased and the fracture resistance can be ensured compared to when compression is performed at the same compression speed and the same compression distance (L1 + L2) as the first compression speed V1. Moreover, since the second compression can be performed following the first compression and the second compression distance L2 can be shortened, it is possible to produce a product with improved production efficiency while maintaining a strength similar to that obtained when produced using only the second compression speed V2.

[0077] In this embodiment, in order to efficiently increase the hardness of the compressed milk powder product, the second compression mode, i.e., the combination of the second compression speed V2 and the second compression distance L2, is determined so as to satisfy the second compression condition that when the compressed milk powder product is compressed from the state compressed by the first compression, it is compressed to a state in which the rate of change in hardness of the compressed milk powder product with respect to the compression distance is reduced.

[0078] As described above, by performing the compression molding process by combining the first compression at the first compression speed V1 and the second compression at the second compression speed V2 which is slower than the first compression speed V1, the hardness of the compressed milk powder can be significantly improved efficiently while minimizing the increase in compression time.

[0079] Although the compression molding process has been described above as being performed by combining the first compression and the second compression, the entire compression molding process may be performed only at the first compression speed V1, or may be performed only at the second compression speed V2.

[0080] The inventors have investigated each compressed and molded milk powder product obtained from various combinations of the first compression speed V1, first compression distance L1, second compression speed V2, and second compression distance L2, and have found that when the second compression speed V2 is made smaller than the first compression speed V1, there is a specific point (hereinafter referred to as a hardness singularity) at which the rate of change (rate of increase) in the hardness of the compressed and molded milk powder product with respect to the change in the second compression distance L2 decreases.The inventors have also found that the second compression distance L2 corresponding to the hardness singularity changes depending on the first compression speed V1 and is also affected by the second compression speed V2.

[0081] It is presumed that the hardness singularity exists because the compressed state changes from one dominated by rearrangement of milk powder particles inside the compressed milk powder molded product to one dominated by plastic deformation inside the compressed milk powder molded product. In addition, the higher the first compression speed V1, the greater the energy required for plastic deformation inside the compressed milk powder molded product. Therefore, it is presumed that the second compression distance L2 corresponding to the hardness singularity changes according to the first compression speed V1, and that the second compression distance L2 is affected by the second compression speed V2.

[0082] Based on the above findings, by performing the second compression so as to satisfy the above second compression conditions, the hardness of the compressed and molded powdered milk product can be significantly improved efficiently while minimizing the increase in compression time.

[0083] It is also preferable to set the compression speed ratio (=V1 / V2), which is the ratio of the first compression speed V1 to the second compression speed V2, to 5 or more. By setting the compression speed ratio to 5 or more, the hardness of the compressed and molded milk powder product can be greatly increased. The compression speed ratio may be 5 or more, and is, for example, 10 or more, 20 or more, 25 or more, 50 or more, 100 or more, 250 or more, or 500 or more.

[0084] Preferably, the first compression speed V1 is set in the range of 1.0 mm / S or more and 100.0 mm / S or less, the first compression distance L1 is set in the range of 5.0 mm or more and 10.0 mm or less, the second compression speed V2 is set in the range of 0.25 mm / S or more and 50.0 mm / S or less, and the second compression distance L2 is set in the range of 0.2 mm or more and 1.6 mm or less.

[0085] The configuration of the above-mentioned tablet press is one example, and the configuration is not limited as long as it can be compressed by changing the compression speed between the first compression and the second compression. In this example, compression is performed to the final thickness in the second compression, but compression may be performed at a speed changed from the second compression speed following the second compression. In this case, the compressed milk powder product is compressed to the final thickness in the compression after the second compression.

[0086] The configuration of the tablet press other than the above is similar to that of the tablet press described in Patent Document 3, for example. For example, the mortar 30A of the slide plate after compression molding is moved to the removal zone. In the removal zone of the tablet press, the lower punch 31 and the upper punch 32 are removed from the mortar 30A of the slide plate 30, and the compressed milk powder is extruded by the extrusion section. The extruded compressed milk powder is collected in a collection tray. In the above tablet press, the milk powder supply section to the mortar 30A of the slide plate 30 is realized by a device including, for example, a funnel that supplies milk powder to the mortar 30A from the bottom opening.

[0087] In the step of compression-molding the milk powder, the environmental temperature is not particularly limited and may be, for example, room temperature. Specifically, the environmental temperature is, for example, 5°C to 35°C. The environmental humidity is, for example, a relative humidity of 0%RH to 60%RH. The compression pressure is, for example, 1MPa to 30MPa, preferably 1MPa to 20MPa. In particular, when solidifying the milk powder, it is preferable to adjust the compression pressure within the range of 1MPa to 30MPa and control the hardness of the compressed milk powder molded product to be within the range of 4N or more and less than 20N. This makes it possible to produce a convenient (easy to handle) and highly practical solid milk 10S. The compressed milk powder molded product has a hardness (for example, 4N or more) that prevents it from losing its shape at least in the subsequent humidifying step and drying step. For example, the preferable range of breaking stress of the compressed milk powder molded product is 0.014N / mm, taking into account the range of the breaking cross-sectional area. 2 Over 0.067N / mm 2 is less than.

[0088] The humidification process is a process of humidifying the compressed milk powder product obtained in the compression molding process. When the compressed milk powder product is humidified, tack (stickiness) occurs on the surface of the compressed milk powder product. As a result, some of the powder particles near the surface of the compressed milk powder product become liquid or gel-like, and cross-link with each other. When the compressed milk powder product is dried in this state, the strength near the surface of the compressed milk powder product can be increased compared to the strength of the interior. By adjusting the time spent in a high-humidity environment (humidification time), the degree of cross-linking (expansion) can be adjusted, and the hardness of the compressed milk powder product (unhardened solid milk 10S) before the humidification process (e.g., 4N or more but less than 20N) can be increased to the desired hardness (e.g., 40N) required for the solid milk 10S. However, the range (width) of hardness that can be increased by adjusting the humidification time is limited. That is, if the compressed milk powder is not hard enough to be transported on a belt conveyer or the like to moisten the compressed milk powder after compression molding, the shape of the solid milk 10S will not be maintained. Also, if the compressed milk powder is too hard during compression molding, only solid milk 10S with a small porosity and poor solubility will be obtained. For this reason, it is preferable to perform compression molding so that the hardness of the compressed milk powder (unhardened solid milk 10S) before the moistening step is sufficiently high and the solubility of the solid milk 10S is sufficiently maintained.

[0089] In the humidification treatment, the method of humidifying the compressed milk powder molded product is not particularly limited, and examples thereof include placing the compressed milk powder molded product in a high-humidity environment, directly spraying water or the like onto the compressed milk powder molded product, and spraying steam onto the compressed milk powder molded product. To humidify the compressed milk powder molded product, a humidifying means is used, and examples of such a humidifying means include a high-humidity chamber, a spray, and steam.

[0090] When the compressed milk powder product is placed in a high humidity environment, it is placed in an environment with a relative humidity of 100% RH or less and a temperature exceeding 100 ° C. When the compressed milk powder product is placed in a high humidity environment, the temperature is preferably 330 ° C or less, preferably 110 ° C or more and 280 ° C or less, more preferably 120 ° C or more and 240 ° C or less, and even more preferably 130 ° C or more and 210 ° C or less. When the compressed milk powder product is placed in a high humidity environment, the relative humidity is preferably 0.1% RH or more and 20% RH or less, more preferably 1% RH or more and 15% RH or less, even more preferably 1.5% RH or more and 12% RH or less, and most preferably 2% RH or more and 10% RH or less. The treatment time when the compressed milk powder product is placed in a high humidity environment is optional, but is, for example, 0.1 seconds or more and 30 seconds or less, preferably 4.4 seconds or more and 20 seconds or less, more preferably 4.4 seconds or more and 12 seconds or less, and even more preferably 5 seconds or more and 10 seconds or less. The processing time can be appropriately set so that the hardness of the solid milk obtained after the drying process described below falls within a predetermined range. Humidification conditions include temperature, humidity, and time. The higher the temperature and humidity, and the longer the time, the greater the humidification effect, and the lower the temperature and humidity, and the shorter the time, the weaker the humidification effect.

[0091] Suitable examples of humidification conditions include the following combinations: temperature is higher than 100°C and not higher than 330°C, relative humidity is 0.1% RH to 20% RH, and treatment time is 0.1 seconds to 30 seconds. Preferably, the temperature is higher than 110°C and not higher than 280°C, relative humidity is 1% RH to 18% RH, and treatment time is 1 second to 20 seconds. More preferably, the temperature is higher than 120°C and not higher than 240°C, relative humidity is 1.5% RH to 17% RH, and treatment time is 2 seconds to 18 seconds. More preferably, the temperature is higher than 120°C and not higher than 240°C, relative humidity is 1.5% RH to 16% RH, and treatment time is 3 seconds to 16 seconds. Even more preferably, the temperature is higher than 125°C and not higher than 230°C, relative humidity is 2% RH to 16% RH, and treatment time is 4 seconds to 14 seconds. Even more preferably, the temperature is higher than 130° C. and not higher than 210° C., the relative humidity is 2% RH or higher and 10% RH or lower, and the treatment time is 5 seconds or higher and 10 seconds or lower. This combination of conditions enables, for example, efficient humidification in a short time.

[0092] The reason for using a temperature environment above 100°C in the embodiment will be explained. As described in Patent Document 2, conventional humidification drying methods use humidified air at 100°C or below. This is because the partial pressure of saturated water vapor under normal pressure (atmospheric pressure) is the same at 100°C as normal pressure (atmospheric pressure), and therefore the temperature of water vapor under normal pressure will be 100°C or below unless special operations are performed. When considering actual production, creating a high-pressure environment other than normal pressure requires processing in a sealed pressure vessel, and batch processing, etc., reduces production efficiency, so it is desirable to be able to process continuously under a normal pressure environment.

[0093] Meanwhile, recent drying technologies have also utilized superheated steam drying, which utilizes "superheated steam" generated by further heating generated steam using a heater or other device to a temperature above the boiling point (over 100°C under normal pressure). Superheated steam is used due to its high drying efficiency using thermal energy, and in this embodiment, this superheated steam is used in the humidification process. This allows for the use of humidity-controlled humidified air at over 100°C (101°C or higher in the sense of being controlled) even under normal pressure. Specifically, humidity can be adjusted by adjusting the amount of steam generated (input), and temperature can be adjusted by the heat output of the heater. In the actual humidification process, hardness is adjusted based on three conditions: temperature, humidity, and time.

[0094] Relative humidity can be measured using a commercially available hygrometer. For example, it can be measured up to 180°C using Vaisala's hygrometer HMT330, and up to 350°C using Vaisala's dew point meter DMT345. Absolute humidity (volume absolute humidity, unit: g / m) can also be measured. 3 ) or weight absolute humidity (unit: kg / kg (DA), where DA is dry air) and calculate the ratio (%) of water vapor partial pressure to saturated water vapor pressure at that temperature to convert to relative humidity.

[0095] The amount of water added to the compressed milk powder product during the humidification treatment (hereinafter also referred to as the "humidification amount") can be adjusted as appropriate. The humidification amount is preferably 0.5% to 3% by weight of the mass of the compressed milk powder product after the compression molding process. If the humidification amount is less than 0.5% by weight, sufficient hardness (tablet hardness) cannot be imparted to the solid milk 10S, which is not preferable. On the other hand, if the humidification amount exceeds 3% by weight, the compressed milk powder product will become excessively liquid or gel-like and dissolve, causing it to deform from its compressed shape or to adhere to equipment such as a conveyer belt during transportation, which is also not preferable.

[0096] The drying process is a process for drying the compressed milk powder that has been moistened in the moistening process. This removes the surface tackiness of the compressed milk powder, making the solid milk 10S easier to handle. In other words, the moistening and drying processes increase the hardness of the compressed milk powder after compression molding, and impart the desired characteristics and quality to the solid milk 10S.

[0097] In the drying treatment, the method for drying the compressed milk powder molded product is not particularly limited, and any known method capable of drying the compressed milk powder molded product that has been subjected to the humidification treatment can be used, such as placing it in a low humidity and high temperature environment, or contacting it with dry air or high temperature dry air.

[0098] When the compressed and molded milk powder is placed in a low-humidity, high-temperature environment, it is placed in an environment with a relative humidity of 0% RH or more and 30% RH or less and a temperature of 80°C or more and 330°C or less. The temperature when placed in a low-humidity, high-temperature environment is, for example, 330°C. The treatment time when placing the compressed and molded milk powder in a low-humidity, high-temperature environment is optional, but is, for example, 0.1 seconds or more and 100 seconds or less.

[0099] The humidification and drying processes can be performed as separate processes under different temperature and humidity conditions, as described above, and can be performed consecutively. The humidification and drying processes can also be performed at the same temperature and humidity, in which case the humidification and drying processes can be performed simultaneously. For example, a compressed milk powder product is placed in a first temperature and humidity environment where humidification and drying occur simultaneously, and then placed in a second temperature and humidity environment where only drying occurs. The transition from the first temperature and humidity to the second temperature and humidity is a period during which the compressed milk powder product transitions from a state in which humidification and drying occur simultaneously to a state in which only drying occurs.

[0100] However, if the solid milk 10S contains a large amount of water, it will have poor shelf life and will be prone to deterioration in flavor and discoloration. Therefore, it is preferable to control (adjust) the water content of the solid milk 10S to within 1% of the water content of the powdered milk used as a raw material by controlling conditions such as the drying temperature and drying time in the drying process.

[0101] The solid milk 10S produced in this way is generally dissolved in warm water for drinking. Specifically, after pouring warm water into a container with a lid, the required number of solid milk 10S is added, or the solid milk 10S is added and then warm water is poured. Then, preferably, the container is gently shaken to quickly dissolve the solid milk 10S, and the solid milk is consumed at an appropriate temperature. Preferably, one to several solid milk 10S (more preferably, one solid milk 10S) are dissolved in warm water to obtain the amount of liquid milk required for one drinking, with the volume of the solid milk 10S being, for example, 1 cm. 3 ~50cm 3 The volume of the solid milk 10S can be adjusted by changing the amount of powdered milk used in the compression molding process.

[0102] As described above, by performing a hardening treatment including a humidification treatment at a temperature of more than 100°C but not exceeding 330°C, it is possible to produce solid milk in which the increase in total crystallization rate Yb (wt%), which is the difference between the ratio of crystals to the total weight at a depth Xb (mm) from the surface of the solid milk and the ratio of crystals inside the solid milk, satisfies the above formula (1).

[0103] (Actions and Effects of Solid Milk 10S) The solid milk 10S of this embodiment is a solid milk obtained by compressing and hardening powdered milk, and the increase in total crystallization rate Yb (wt%), which is the difference between the ratio of crystals to the total weight at a depth Xb (mm) from the surface of the solid milk 10S and the ratio of crystals inside the solid milk, satisfies the above formula (1).

[0104] The following describes the case where a compressed and molded product of powdered milk obtained by compression molding is moistened at a temperature of 100°C or less. The increase in total crystallinity Ybr (wt%), which is the difference between the ratio of crystals to the total weight at a depth Xbr (mm) from the surface of solid milk 10Sr produced by hardening treatment including moistening treatment at a temperature of 100°C or less, and the ratio of crystals inside the solid milk, is expressed by the following formula (1r):

[0105] Ybr=-5.24Xbr+6.65 (1r)

[0106] As can be seen from a comparison of formula (1) and formula (1r), the increase Yb in the total crystallinity rate of solid milk 10S of this embodiment is smaller than the increase Ybr in the total crystallinity rate of solid milk 10Sr produced by subjecting the solid milk from its surface to its interior to a hardening treatment that includes a humidification treatment in which the solid milk is humidified at a temperature of 100° C. or less. In other words, in solid milk 10S of this embodiment, the impact of the humidification treatment (hardening treatment) on the interior of the solid milk is small.

[0107] Such solid milk 10S satisfies the above formula (1) and has a small increase in the total crystallization rate, thereby achieving suitable solubility, and also ensuring sufficient strength for easy handling even in the case of a hardening treatment that is unlikely to affect the interior of the solid milk.

[0108] When the above solid milk 10S satisfies the above formula (2), the increase in the total crystallization rate is further reduced, and more suitable solubility can be achieved.

[0109] The reason why solubility improves when the humidification treatment for hardening is performed at a temperature above 100°C is thought to be that when hardening treatment is performed at a temperature above 100°C, a crosslinked structure is formed when some of the powder particles become liquid or gel-like due to humidification, resulting in a structure with higher solubility compared to the crosslinked structure formed by conventional methods in which humidification is performed at temperatures below 100°C. More specifically, it is thought that some of the powder particles near the surface of the compressed milk powder product soften when humidified at a temperature above 100°C, causing the sugars to become in an amorphous rubber state, crosslinking each other at the contact points between adjacent particles, and then vitrifying (solidifying in an amorphous state) when dried, resulting in a structure with even higher solubility.

[0110] Second Embodiment Solid milk is an example of a solid food. The first embodiment is a compressed milk powder product obtained by compressing and molding milk powder, and a solid milk obtained by hardening the compressed milk powder, but the present invention is not limited to this. This embodiment is applied to a compressed food powder product obtained by compressing and molding food powder, and a solid food obtained by hardening the compressed food powder.

[0111] In addition to milk powder, the food powder may be, for example, a protein powder such as whey protein, soy protein, or collagen peptide, an amino acid powder, or an oil-containing powder such as MCT oil. Lactose or other carbohydrates may be added to the food powder as appropriate. In addition to lactose or other carbohydrates, the food powder may also contain nutritional components such as fat, protein, minerals, and vitamins, as well as food additives.

[0112] Food powder can be compressed into a desired shape to form a food powder compression molded product. The resulting food powder compression molded product can then be hardened to form a solid food product. Except for using the above food powder as a raw material, this can be produced by carrying out a hardening process, including a humidification process, similar to that of the first embodiment. That is, in the humidification process, the food powder compression molded product is humidified at a temperature of, for example, more than 100°C and not more than 330°C.

[0113] The hardness of a food powder compression molded product obtained by compressing and molding food powder, and a solid food product obtained by hardening the same, can be measured using the hardness meter described in the first embodiment. The preferred hardness of a food powder compression molded product is 4N or more and less than 20N, and the preferred hardness of a solid food is 20N or more and 100N or less. The preferred breaking stress of a food powder compression molded product is 0.014N / mm 2 Over 0.067N / mm 2 The preferred breaking stress of solid food is less than 0.067N / mm 2 More than 0.739N / mm 2 The following is the result.

[0114] The solid food of this embodiment is configured such that the increase in total crystallinity Ya (wt%), which is the difference between the ratio of crystals to the total weight at a depth Xa (mm) from the surface of the solid food and the ratio of crystals inside the solid food, satisfies the following formula (1A): Such a solid food can be produced by compression-molding a food powder compression-molded product, and then subjecting the resulting product to a hardening treatment that includes a humidification treatment at a temperature of more than 100°C and not more than 330°C, for example, and can ensure easy-to-handle strength and achieve favorable solubility.

[0115] Ya<-5.24Xa+6.65 (1A)

[0116] In the solid food of this embodiment, the increase in total crystallinity Ya (wt %) at a depth Xa (mm) from the surface of the solid food preferably satisfies the following formula (1A-1).

[0117] Ya<-5.24Xa+6.15 (1A-1)

[0118] The increase in the total crystallinity Ya (wt %) more preferably satisfies the following formula (1A-2).

[0119] Ya<-5.24Xa+5.65 (1A-2)

[0120] In the solid food of the present embodiment, the increase in total crystallinity Ya (wt %) at a depth Xa (mm) from the surface of the solid food preferably satisfies the following formula (2A).

[0121] Ya≦6.34Xa 2 -11.15Xa+5.05 (2A)

[0122] The increase in the total crystallinity Ya (wt %) more preferably satisfies the following formula (2A-1).

[0123] Ya≦4.89Xa 2 -8.39Xa+3.51 (2A-1)

[0124] The increase in the total crystallinity Ya (wt %) more preferably satisfies the following formula (2A-2).

[0125] Ya≦6.40Xa 2 -7.59Xa+2.28 (2A-2)

[0126] Furthermore, the protein powder of the above food powder may be milk casein, meat powder, fish powder, egg powder, wheat protein, wheat protein hydrolysate, etc. These protein powders may be used alone or in combination of two or more.

[0127] Furthermore, the whey protein (whey protein) in the above-mentioned food powder is a general term for proteins in milk excluding casein. It may be classified as whey protein. Whey protein is composed of multiple components such as lactoglobulin, lactalbumin, and lactoferrin. When a dairy raw material such as milk is acidified, the protein that precipitates is casein, and the protein that does not precipitate is whey protein. Examples of powder raw materials containing whey protein include WPC (whey protein concentrate, protein content of 75 to 85% by mass) and WPI (whey protein isolate, protein content of 85% by mass or more). These may be used alone or in combination of two or more types.

[0128] Furthermore, the soy protein (soy protein) in the food powder described above may be any protein contained in soybeans, and may be extracted from soybeans. It may also be purified from raw soybeans. The purification method is not particularly limited, and conventionally known methods can be used. As such soy protein, powders commercially available as ingredients for food and beverages, medical materials, and food supplements can be used. These may be used alone or in combination of two or more types.

[0129] Furthermore, the amino acids contained in the amino acid powder of the above-mentioned food powder are not particularly limited, but examples thereof include 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. These may be used alone or in combination of two or more.

[0130] The amino acids contained in the amino acid powder of the food powder may be either natural or synthetic, and may be single amino acids or mixtures of multiple amino acids. In addition to free amino acids, salts such as sodium salts, hydrochlorides, and acetate salts, as well as derivatives such as carnitine and ornithine, may also be used. As used herein, "amino acids" include α-amino acids, β-amino acids, and γ-amino acids. Furthermore, amino acids may be in either the L- or D-form.

[0131] Furthermore, the fats and oils contained in the fat-containing powder of the food powder include, in addition to the above-mentioned MCT oil, 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 include, for example, milk fat, lard, beef tallow, and fish oil. Vegetable fats and oils include, for example, soybean oil, rapeseed oil, corn oil, coconut oil, palm oil, palm kernel oil, safflower oil, cottonseed oil, linseed oil, and MCT oil.

[0132] Furthermore, the carbohydrates of the food powders include, in addition to the lactose mentioned above, oligosaccharides, monosaccharides, polysaccharides, and artificial sweeteners. One or more of these may be added. Oligosaccharides include, for example, lactose, sucrose, maltose, galactooligosaccharides, fructooligosaccharides, and lactulose. Monosaccharides include, for example, glucose, fructose, and galactose. Polysaccharides include, for example, starch, soluble polysaccharides, and dextrin.

[0133] Furthermore, an example of a food additive for the food powder is a sweetener. Any sweetener commonly used in foods and pharmaceuticals can be used as the sweetener, and it may be either a natural sweetener or a synthetic sweetener. The sweetener is not particularly limited, but examples include 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.

[0134] Furthermore, an example of a food additive for the food powder is an acidulant. The acidulant is not particularly limited, but includes, 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. The acidulant can suppress (mask) the bitterness caused by the type of amino acid.

[0135] Furthermore, the nutritional components of the food powder may include any components such as fat, protein, minerals, and vitamins.

[0136] Examples of fats include animal fats, vegetable fats, their fractionated oils, hydrogenated oils, and interesterified oils. One or more of these may be added. Animal fats include milk fat, lard, beef tallow, and fish oil. Vegetable fats include soybean oil, rapeseed oil, corn oil, coconut oil, palm oil, palm kernel oil, safflower oil, cottonseed oil, linseed oil, and MCT oil.

[0137] Examples of proteins include milk proteins and milk protein fractions, animal proteins, vegetable proteins, peptides obtained by decomposing these proteins into various chain lengths using enzymes or the like, and amino acids. One or more of these may be added. Examples of milk proteins include casein, whey proteins (α-lactalbumin, β-lactoglobulin, etc.), whey protein concentrates (WPC), and whey protein isolates (WPI). Examples of animal proteins include egg proteins (egg powder), meat powder, and fish powder. Examples of vegetable proteins include soybean proteins and wheat proteins. Examples of peptides include collagen peptides. Examples of amino acids include taurine, cystine, cysteine, arginine, and glutamine. One or more of these may be added.

[0138] The minerals include iron, sodium, potassium, calcium, magnesium, phosphorus, chlorine, zinc, iron, copper, selenium, etc. One or more of these may be added.

[0139] 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.

[0140] Other food ingredients include, for example, cocoa powder, cacao powder, chocolate powder, microbial powder containing beneficial microorganisms such as lactic acid bacteria and bifidobacteria, fermented milk ingredient powder made by adding microorganisms to milk and fermenting it, cheese powder made by powdering cheese, functional food powder made by powdering functional foods, complete nutritional food powder made by powdering complete nutritional foods, etc. One or more of these may be added.

[0141] The solid food according to the present invention may be in the form of a food for daily consumption, a health food, a health supplement, a food with health claims, a food for specified health uses, a food with nutrient functions, a supplement, a food with functional claims, or the like.

[0142] Solid foods that have the property of dissolving in water are also called solid soluble foods.

[0143] When food powder contains water-soluble or hygroscopic ingredients, tack (stickiness) may occur on the surface of the food powder compression molded product when the food powder is compressed and molded into a compressed food powder product. Examples of such food powders include food powders containing sugar, dextrin, natural carbohydrates (trehalose, etc.), polysaccharides, etc. Other food powders that may cause tack (stickiness) on the surface of the food powder compression molded product when humidified are also suitable.

[0144] (Actions and effects of solid foods) The solid food of this embodiment is a solid food that has been compressed and hardened from food powder, and the increase in total crystallinity Ya (wt %), which is the difference between the ratio of crystals to the total weight at a depth Xa (mm) from the surface of the solid food and the ratio of crystals inside the solid food, satisfies the above formula (1A).

[0145] The following describes the case where a food powder compression molded product obtained by compression molding food powder is humidified at a temperature of 100°C or less. The increase in total crystallinity Yar (wt%), which is the difference between the ratio of crystals to the total weight at a depth Xar (mm) from the surface of a solid food produced by a hardening process that includes a humidification process in which the food powder is humidified at a temperature of 100°C or less, and the ratio of crystals inside the solid food, is expressed by the following formula (1Ar):

[0146] Yar=-5.24Xar+6.65 (1Ar)

[0147] As can be seen from a comparison of formula (1A) and formula (1Ar), the increase Ya in the total crystallinity of the solid food of this embodiment is smaller than that of a solid food produced by carrying out a hardening treatment that includes a humidification treatment in which the solid food is humidified from the surface to the interior at a temperature of 100° C. or less. In other words, in the solid food of this embodiment, the impact of the humidification treatment (hardening treatment) on the interior of the solid food is small.

[0148] Such solid foods can achieve suitable solubility by satisfying the above formula (1A) and reducing the increase in the total crystallization rate, and can ensure sufficient strength for easy handling even when subjected to a hardening treatment that is unlikely to affect the interior of the solid food.

[0149] When the above solid food satisfies the above formula (2A), the increase in the total crystallization rate is further reduced, and more suitable solubility can be achieved.

[0150] <First Example> (Preparation of Examples 1, 2 and 3) As an example, a rectangular solid milk sample was prepared with a side a in the X-axis direction of 31 mm, a side b in the Y-axis direction of 24 mm, and a side c in the Z-axis direction of 12.5 mm. The size of the tablet press's mortar and pestle was adjusted to achieve this size, and 5.4 g of powdered milk was compression-molded to form a compressed milk powder product. In the compression molding, a first compression was performed with a first compression distance L1 of 12.6 mm and a first compression speed V1 of 120 mm / s, followed by a second compression with a second compression distance L2 of 0.6 mm and a second compression speed V2 of 1.2 mm / s. The compressed milk powder product obtained above was subjected to a humidification treatment at a humidification temperature (humidification time) of 101°C (9.2 seconds), and then a drying treatment at a drying temperature of 80°C, resulting in a solid milk sample according to Example 1 that had been subjected to a hardening treatment. The drying time was adjusted so that the weight increase during humidification could be completely dried. Similarly, a solid milk sample according to Example 2 was prepared by setting the humidification temperature (humidification time) to 200°C (7.6 seconds). Also, a solid milk sample according to Example 3 was prepared by setting the humidification temperature (humidification time) to 300°C (5.6 seconds).

[0151] (Creating a comparative example) A solid milk sample was prepared as a comparative example, which differed from the example only in that the humidification treatment in the hardening treatment was carried out at 75°C (45 seconds).

[0152] (Hardness of each sample) The hardness of each sample of solid milk according to Examples 1 to 3 and Comparative Example was evaluated using the load cell type tablet hardness tester. The hardness of each sample was approximately 50 N (breaking stress was 0.167 N / mm 2 The hardness was sufficient and easy to handle.

[0153] (Measurement of the increase in total crystallinity for each sample) For each sample of solid milk according to Examples 1 to 3 and Comparative Example, a profile of the increase Y in total crystallinity in the direction of depth X from the surface was determined by XRD (X-ray diffraction). The increase in total crystallinity is the difference between the ratio of crystals to the total weight at each depth from the surface of the solid milk and the ratio of crystals inside the solid milk. Here, the increase was determined as the weight (wt%) of α-lactose crystals and β-lactose crystals per unit weight of crystals.

[0154] The increase in total crystallinity of each sample was measured using a powder X-ray diffractometer (XRD, SmartLab, Rigaku Corporation) by measuring the diffraction intensity of the exposed surface, cut from the solid milk surface in 0.1 mm increments. The measurement method was general (focusing), and the slit conditions were scan axis (2θ / θ), mode (step), range (absolute), start (9.0000°), end (13.5000°), step (0.0200°), speed count time (2.4), IS (1.000°), RSI (1.000°), RS2 (0.300 mm), attenuator (open), tube voltage (40 kV), and tube current (30 mA).

[0155] The analysis was performed using the analysis software "SmartLab Studio II," which involved weighted averaging (seven-point smoothing) and background removal (Sonnenveld-Visser method), followed by integrated intensity calculation (specific peak of α-lactose crystals: 12.5, specific peak of β-lactose crystals: 10.5). The increase in total crystallinity is the difference between the ratio of crystals to the total weight at each depth from the surface of the solid milk and the ratio of crystals inside the solid milk. Here, it was calculated as the weight (wt%) of α-lactose crystals and β-lactose crystals per unit weight of crystals.

[0156] FIG. 7 is a graph showing the increase Y (increase from the center) in the total crystallinity rate versus the depth X (mm) from the surface of the solid milk according to the example. The increase in the total crystallinity rate of the comparative example is indicated by the symbol "○", and the graph approximating this using the least squares method is shown as a line a1 (Y = -5.24X + 6.65). The increase in the total crystallinity rate of Example 1 is indicated by the symbol "+", and the graph approximating this using the least squares method is shown as a curve b1 (Y = 6.34X 2 The increase in the total crystallinity in Example 2 is indicated by the symbol "□", and the graph obtained by approximating this by the least squares method is the curve c1 (Y=4.89X + 5.05). 2 The increase in the total crystallinity in Example 3 is indicated by the symbol "△", and the graph obtained by approximating this by the least squares method is the curve d1 (Y=6.40X + 3.51). 2 -7.59X+2.28).

[0157] As shown in FIG. 7, the curves of Examples 1 to 3 are all below the curve of the Comparative Example, and satisfy the condition Y<-5.24X+6.65. The small increase in the total crystallization rate allows for favorable solubility, and also ensures sufficient strength for easy handling even during hardening treatment, which is difficult for the effects to reach the interior of the solid milk. In particular, the curve b1 of Example 1 (Y=6.34X 2 When the crystallinity is above or below (-11.15X+5.05), the increase in the total crystallinity is further reduced, and more suitable solubility can be achieved.

[0158] (Solubility test of each sample) To evaluate the solubility depending on the curing conditions, a solubility test was conducted on the solid milk samples of Examples 1 to 3 and Comparative Example prepared as described above. First, one solid milk sample was placed in a stirring basket. The stirring basket was a cylindrical, lidded container with a bottom, an inner diameter of 30 mm, and a height of 36 mm, and had sides, a bottom, and a lid. The sides, bottom, and lid were formed from a stainless steel mesh with an 18-mesh mesh (1.01 mm opening). Four blades were evenly spaced on the inner surface of the side of the stirring basket. Each of the four blades was a plate with a thickness of 1.5 mm, a width of 4 mm, and a length of 34 mm, and was arranged with its longitudinal direction parallel to the central axis of the stirring basket and protruding from the inner surface of the side toward the center. The stirring basket was immersed in 200 ml of warm water (50±1°C) contained in a 300 ml beaker, and with the solid milk sample completely submerged, the stirring basket was rotated at a rotational speed of 0.5 m / s (circumferential velocity). The stirring basket was held at a height of 5 mm from the inner bottom surface of the beaker. The dissolution process from the start of dissolution of the solid milk sample until it was completely dissolved was measured at regular intervals using electrical conductivity.

[0159] The above test was carried out on three pieces for each Example and Comparative Example, and the 20% dissolution time (t 20 ), 63% elution time (t 63 ), 95% elution time (t 95The 20% dissolution time, 63% dissolution time, and 95% dissolution time of the comparative example were compared with the reference values ​​(t 20ref , t 63ref , and t 95ref ) and calculate the solubility index (I d The 20% dissolution time (t 20ref ) is 14 seconds, and 63% dissolution time (t 63ref ) is 32 (seconds), and the 95% dissolution time (t 95ref ) was 93 (seconds).

[0160] I d =(t 20 / t 20ref +t 63 / t 63ref +t 95 / t 95ref ) / 3···(A)

[0161] Dissolution tests for general tablets (medicines) are conducted by comparing the time to reach 85% concentration or the time to reach 60% and 85% concentration. However, with solid milk, depending on the variety and manufacturing conditions, dissolution may stagnate initially or take a long time to complete. Therefore, it is not appropriate to evaluate the solubility of solid milk using a one- or two-point index, as is the case with general tablets. In particular, an extension of the initial dissolution time is a factor that users perceive as "difficult to dissolve" in sensory evaluation, and is therefore important in evaluating the quality of solid milk.

[0162] The solubility index (I d In the equation for solubility index (I), the 20% dissolution time was used to evaluate solubility in the early dissolution stage, the 63% dissolution time was used to evaluate solubility in the middle dissolution stage, and the 95% dissolution time was used to evaluate solubility in the late dissolution stage. The 63% dissolution time, which indicates solubility in the middle dissolution stage, corresponds to the time constant τ in a general transient response, and is widely known as a value that indicates the response characteristics in the evaluation index of the response characteristics of various sensors. The 95% dissolution time, which indicates solubility in the final dissolution stage, theoretically corresponds to an evaluation index that indicates the response characteristics at 3τ with respect to the time constant τ. The above solubility index (I d) is calculated by taking the arithmetic mean of the dissolution times of the initial, middle, and final stages of dissolution, and the solubility index (I d ) is defined as follows.

[0163] The resulting solubility index (I d ) was smaller than 1 in all of Examples 1 to 3, and it is believed that the improved solubility in Examples 1 to 3 was due to the temperature condition of the humidification treatment being over 100°C and the treatment time being shortened.

[0164] (Free Fat Measurement Test) To evaluate the free fat content depending on the hardening conditions, the free fat content of the solid milk samples of the Examples and Comparative Examples prepared as described above was measured. First, the solid milk was pulverized using a cutter, taking care not to crush it. The pulverized solid milk was then passed through a 32-mesh sieve. The samples that had passed through the sieving process were used to measure the free fat content according to the method described in "Determination of Free Fat on the Surface of Milk Powder Particles," Analytical Method for Dry Milk Products, A / S NIRO ATOMIZER (1978). However, in the method for dissolving solid milk (Niro Atomizer, 1978), the extraction solvent was changed from carbon tetrachloride to n-hexane, and the extraction procedure was changed accordingly. It has been confirmed in "Study on the measurement method of free fat in powdered milk," Shibata Mitsuho, Hama Hatsumi, Imai Mami, and Toyoda Katsu, Nihon Shokuhin Kagaku Kougaku Kaishi Vol. 53, No. 10, 551-554 (2006) that these changes do not change the measurement results of free fat. It was confirmed that the free fat content of all samples in Examples 1 to 3 was lower than that of the comparative example. This is thought to be due to differences in the hardening treatment conditions, specifically, the temperature condition of the humidification treatment being above 100°C and the treatment time being shortened, resulting in the lower free fat content in Examples 1 to 3.

[0165] In the solid milk of this example, the free fat content is kept lower than in the comparative example within the same hardness range. This is because the difference in the hardening treatment conditions, specifically the adjustment of the humidification conditions (temperature, humidity, and time), reduces the occurrence of crystals compared to the comparative example. More specifically, in the solid milk of this example, the sugars become an amorphous rubber state upon humidification, cross-linking occurs at the contact points between adjacent particles, and then vitrification (solidification in an amorphous state) occurs upon drying, which reduces the occurrence of crystals.

[0166] When an amorphous state changes to a crystalline state, the oils and fats present near the crystal surface are subjected to excessive shear as they crystallize (a solid suddenly appears), and free fat is generated.

[0167] In the solid milk of this example, crystallization is unlikely to occur, and therefore shear force is unlikely to be applied to the fat, and as a result, the content of free fat is kept low.

[0168] <Second Example> Solid milk according to the example was prepared in the same manner as in Example 1. The humidification temperature was 125°C to 230°C, the relative humidity was 2% (2% RH) to 16% (16% RH), and the treatment time was 3 to 20 seconds. The drying temperature was over 100°C to 330°C, and the treatment time was 5 to 50 seconds. The increase in total crystallinity Yb (wt%), which is the difference between the ratio of crystals to the total weight at a depth Xb (mm) from the surface of the obtained solid milk and the ratio of crystals inside the solid milk, was measured, and it satisfied the above formula (1). Furthermore, some solid milks satisfied the above formula (2).

[0169] The hardness of the solid milk produced in the example is 49N to 52N (the breaking stress at 50N is 0.167N / mm 2 ), and all of them had a hardness that was easy to handle. The solubility test was carried out on the obtained solid milk in the same manner as in Example 1 and the comparative example described in Example 1. The solubility index (I d) was smaller than 1.00, which was lower than that of the comparative example. Furthermore, when the obtained solid milk was subjected to a free fat measurement test in the same manner as in Example 1, it was confirmed that the free fat content was lower in all of the examples than in the comparative example.

[0170] <Third Example> Solid milk according to the example was prepared in the same manner as in Example 1. The temperature of the humidification treatment was higher than 100°C and lower than 125°C, and other conditions (relative humidity and treatment time of the humidification treatment, temperature and treatment time of the drying treatment, etc.) were the same as in Example 2. All of the prepared solid milks of the examples had a hardness that made them easy to handle. When a solubility test and a free fat measurement test were conducted, the solid milk of Example 3 had lower hardness than the comparative example, as with Example 2. When the solid milks of Example 2 and Example 3 were compared, the solid milk of Example 2 was superior to the solid milk of Example 3 in terms of solubility and free fat.

[0171] <Example of embodiment> The present disclosure may have the following configuration: If the following configuration is provided, the composition can have suitable solubility and strength that is easy to handle.

[0172] (1) A solid food product obtained by compression molding food powder, wherein the increase in total crystallinity Ya (wt%), which is the difference between the ratio of crystals to the total weight at a depth Xa (mm) from the surface of the solid food and the ratio of crystals inside the solid food, satisfies the following formula (1A): Ya<-5.24Xa+6.65 (1A)

[0173] (2) A solid food according to (1), wherein the increase in total crystallinity Ya (wt%) at a depth Xa (mm) from the surface of the solid food satisfies the following formula (2A): Ya≦6.34Xa 2 -11.15Xa+5.05 (2A)

[0174] (3) A solid milk obtained by compressing and molding powdered milk, in which the increase in total crystallization rate Yb (wt%), which is the difference between the ratio of crystals to the total weight at a depth Xb (mm) from the surface of the solid milk and the ratio of crystals inside the solid milk, satisfies the following formula (1): Yb<-5.24Xb+6.65 (1)

[0175] (4) The solid milk according to (3), wherein the increase Yb (wt %) in the total crystallinity at a depth Xb (mm) from the surface of the solid milk satisfies the following formula (2): Yb≦6.34Xb 2 -11.15Xb+5.05 (2)

[0176] (5) A solid food product obtained by compression molding food powder, wherein the food powder is compression molded so that the increase in total crystallinity Ya (wt%), which is the difference between the ratio of crystals to the total weight at a depth Xa (mm) from the surface of the solid food and the ratio of crystals inside the solid food, satisfies the following formula (1A), and the resulting food powder compression molded product is subjected to a hardening treatment. Ya<-5.24Xa+6.65 (1A)

[0177] (6) A solid milk obtained by compression molding powdered milk, which is formed by compression molding powdered milk and then subjecting the resulting compressed milk powder to a hardening treatment so that the increase in total crystallization rate Yb (wt%), which is the difference between the ratio of crystals to the total weight at a depth Xb (mm) from the surface of the solid milk and the ratio of crystals inside the solid milk, satisfies the following formula (1): Yb<-5.24Xb+6.65 (1)

[0178] (7) A solid food product obtained by compressing and molding food powder, the breaking stress of which is 0.067 N / mm 2 More than 0.739N / mm 2A solid food product in which the increase in total crystallinity Ya (wt%), which is the difference between the ratio of crystals to the total weight at a depth Xa (mm) from the surface of the solid food and the ratio of crystals inside the solid food, satisfies the following formula (1A): Ya<-5.24Xa+6.65 (1A)

[0179] (8) A solid milk obtained by compressing and molding powdered milk, the breaking stress of which is 0.067 N / mm 2 More than 0.739N / mm 2 or less, and the increase in total crystallinity Yb (wt%), which is the difference between the ratio of crystals to the total weight at a depth Xb (mm) from the surface of the solid milk and the ratio of crystals inside the solid milk, satisfies the following formula (1): Yb<-5.24Xb+6.65 (1)

[0180] (9) A solid dissolvable food product obtained by compressing and molding food powder, wherein the increase in total crystallization rate Ya (wt%), which is the difference between the ratio of crystals to the total weight at a depth Xa (mm) from the surface of the solid dissolvable food product and the ratio of crystals inside the solid dissolvable food product, satisfies the following formula (1A): Ya<-5.24Xa+6.65 (1A)

[0181] (10) A solid food product obtained by compression molding food powder, in which the increase in total crystallinity Ya (wt%), which is the difference between the ratio of crystals to the total weight at a depth Xa (mm) from the surface of the solid food and the ratio of crystals inside the solid food, satisfies the following formula (1A): Ya<-5.24Xa+6.65 (1A) [Explanation of symbols]

[0182] 10 Main Unit 10A 1st side 10B 2nd side 10C side 10S solid milk

Claims

[Claim 1] A solid milk obtained by compressing and hardening powdered milk, The increase in total crystallization rate Yb (wt%), which is the difference between the weight (wt%) of α-lactose crystals and β-lactose crystals per unit weight at a depth Xb (mm) from the surface of the solid milk and the weight (wt%) of α-lactose crystals and β-lactose crystals per unit weight inside the solid milk, satisfies the following formula (2): The interior of the solid milk refers to a region in which the total crystallinity does not change or does not substantially change before and after the hardening treatment. solid milk. Yb≦6.34Xb 2 -11.15Xb+5.05 (2)

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