Methods for producing solid foods

Abstract

Provided are a method for producing a solid food product having suitable solubility and strength that is easy to handle, and a method for producing solid milk. [Solution] A method for producing a solid food product by compression molding food powder, comprising the steps of: compressing and molding the food powder to form a food powder compression molded product; and hardening the food powder compression molded product, wherein the hardening process includes placing the food powder compression molded product in an environment with a humidity of 100% RH or less and a temperature exceeding 100°C.

Description

[Technical field]

[0001] The present invention relates to a method for producing a solid food product and a method for producing solid milk. [Background technology]

[0002] As a solid food, solid milk obtained by compressing and molding milk powder is known (see Patent Documents 1 and 2). This solid milk is required to have solubility so that it can dissolve quickly when placed in warm water, and is also required to have transportability, i.e., fracture resistance so that it does not break or crumble during transportation or carrying. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 5350799 [Patent Document 2] Patent No. 5688020 Summary of the Invention [Problem to be solved by the invention]

[0004] There is a demand for solid foods and solid milks that are produced by compression molding of powders or powdered milk and have strength that makes them easy to handle while also improving their solubility.

[0005] An object of the present invention is to provide a method for producing a solid food having suitable solubility and strength that is easy to handle, and a method for producing solid milk. [Means for solving the problem]

[0006] The method for producing a solid food according to the present invention is a method for producing a solid food obtained by compression-molding food powder, and includes the steps of: compressing and molding the food powder to form a food powder compression-molded product; and hardening the food powder compression-molded product, the hardening treatment including placing the food powder compression-molded product in an environment with a humidity of 100% RH or less and a temperature exceeding 100°C.

[0007] The method for producing solid milk according to the present invention is a method for producing solid milk in a solid form by compression-molding milk powder, and includes a step of compressing and molding the milk powder to form a compressed milk molded product, and a step of performing a hardening treatment on the compressed milk molded product, the hardening treatment including a step of placing the compressed milk molded product in an environment with a humidity of 100% RH or less and a temperature exceeding 100°C. Effect of the Invention

[0008] According to the method for producing a solid food of the present invention, it is possible to produce a solid food having excellent solubility while having the same hardness as conventional solid foods. Therefore, the method for producing a solid food of the present invention can produce a solid food having suitable solubility and strength that is easy to handle.

[0009] According to the method for producing solid milk of the present invention, it is possible to produce solid milk that has a hardness equivalent to that of conventional solid milk and has excellent solubility. Therefore, the method for producing solid milk of the present invention can produce solid milk that has suitable solubility and strength that is easy to handle. [Brief description of the drawings]

[0010] [Figure 1] FIG. 2 is a perspective view of solid milk according to an embodiment. [Diagram 2] FIG. 11 is a perspective view of solid milk according to a modified example. [Diagram 3] 1 is a graph showing the change in dissolution rate over time. [Figure 4] 1 is a graph showing the results of evaluating solubility. [Diagram 5] 1 is a graph showing the results of measuring the free fat content. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Hereinafter, an embodiment of the present invention will be described. However, the embodiment described below is merely an example, and can be appropriately modified within a scope obvious to a person skilled in the art.

[0012] <Embodiment Mode> (Composition of solid milk 10S) FIG. 1 is a perspective view of solid milk 10S according to this embodiment.

[0013] The solid milk 10S has a solid body 10 obtained by compression molding of milk powder. 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 outline shape of the body 10 is a cylinder, an elliptical cylinder, a cube, a rectangular parallelepiped, a plate, a polygonal column, a polygonal truncated pyramid, a polyhedron, or the like. From the viewpoint of ease of molding and convenience of transportation, a cylinder, an elliptical cylinder, and a rectangular parallelepiped are preferred. The main body 10 of the solid milk 10S shown in FIG. 1 has a schematic shape of a rectangular parallelepiped with dimensions a×b×c (see FIG. 1), and the main body 10 has a side 10C parallel to the XZ plane or the YZ plane.

[0014] The corners of the main body 10 consisting of the first surface 10A and the side surface 10C and the corners of the main body 10 consisting of the second surface 10B and the side surface 10C are chamfered to form tapered inclined surfaces. The corners of the side surface 10C consisting of a surface parallel to the YZ plane and a surface parallel to the XZ plane may be rounded. By chamfering or rounding the corners, it is possible to prevent the solid milk 10S from being broken during transportation, etc.

[0015] 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 further hardened by hardening treatment. The surface layer in this embodiment is a layer that is harder than the inside. Here, the surface layer being harder than the inside means that the force required to separate only the surface layer is relatively greater than the force required to separate the inside.

[0016] 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.

[0017] Milk powder is produced from liquid milk (liquid milk) containing milk components (for example, components of cow's milk). Milk components are, for example, raw milk (full fat milk), skim milk, cream, etc. The moisture content of liquid milk is, for example, 40% by weight to 95% by weight. The moisture content of milk powder is, for example, 1% by weight to 5% by weight. The milk powder may have nutritional components added thereto, which will be described later. The milk powder may be whole milk powder, skim milk powder, or creamy powder, so long as it is suitable for producing solid milk 10S. The fat content of milk powder is, for example, preferably 5% by weight to 70% by weight.

[0018] The solid milk 10S of the present embodiment may contain emulsified fat and free fat as fat. The free fat is fat that seeps out of the milk powder when the emulsion state is broken by pressure. Since the milk powder is an emulsion, when the milk powder is solidified by applying pressure, the emulsion state is broken by pressure. This free fat is easily oxidized and impairs the flavor of the milk powder. In addition, when the milk powder is dissolved in warm water, there is a problem that the excess free fat floats on the water surface and aggregates (this phenomenon is called "oil off"). The free fat content of the solid milk 10S is 0.5% by weight or more and 4% by weight or less, preferably 0.8% by weight or more and 1.2% by weight or less. The free fat content of the solid milk 10S is lower than that of conventional solid milk. The conventional solid milk here refers to solid milk in which the hardening treatment described later is performed under conventional conditions.

[0019] Free fat can be measured as follows. First, the solid milk is finely ground with a cutter, taking care not to crush it (grinding process). The ground solid milk is then passed through a 32 mesh sieve (sieving process). The sample that has passed through the sieving process is 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). The free fat content measured by this method is expressed as the weight percentage of fat extracted with an organic solvent (e.g., n-hexane or carbon tetrachloride) by shaking at a constant speed for a fixed period of time.

[0020] The milk components used as the raw materials for the above-mentioned milk powder are derived from raw milk, for example. Specifically, they are derived from raw milk of cows (Holstein, Jersey, and others), goats, sheep, buffaloes, etc. The above-mentioned raw milk contains fat, but it may be milk with an adjusted fat content in which part or all of the fat has been removed by centrifugation or the like.

[0021] The nutritional components that are the raw materials for the powdered milk are, for example, fat, protein, carbohydrate, minerals, vitamins, etc. One or more of these may be added.

[0022] Proteins that can be the raw material of the above-mentioned milk powder include, for example, milk proteins and milk protein fractions, animal proteins, vegetable proteins, peptides and amino acids obtained by decomposing these proteins into various chain lengths using enzymes or the like. 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. Examples of vegetable proteins include soybean proteins and wheat proteins. Examples of amino acids include taurine, cystine, cysteine, arginine, and glutamine.

[0023] The fats (oils and oils) that can be used as raw materials for the above-mentioned milk powder are animal fats and oils, vegetable fats and oils fractionated therefrom, hydrogenated oils and interesterified oils. One or more of these may be added. Examples of animal fats and oils include milk fat, lard, beef tallow and fish oil. Examples of vegetable fats and oils include soybean oil, rapeseed oil, corn oil, coconut oil, palm oil, palm kernel oil, safflower oil, cottonseed oil, linseed oil and MCT (Medium Chain Triglyceride) oil.

[0024] 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. Examples of oligosaccharides include lactose, sucrose, maltose, galactooligosaccharides, fructooligosaccharides, and lactulose. Examples of monosaccharides include glucose, fructose, and galactose. Examples of polysaccharides include starch, soluble polysaccharides, and dextrin. Note that non-saccharide artificial sweeteners may be used instead of or in addition to the saccharide artificial sweeteners.

[0025] 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. In addition to or in place of the minerals sodium, potassium, calcium, magnesium, iron, copper, and zinc, one or both of phosphorus and chlorine may be used.

[0026] In the solid milk 10S, there are many voids (e.g., pores) that are generated when the powdered milk, which is the raw material of the solid milk 10S, is compressed and molded. It is preferable that these multiple voids are uniformly dispersed (distributed) in the solid milk 10S, so that the solid milk 10S can be dissolved without bias and the solubility of the solid milk 10S can be increased. Here, the larger (wider) the voids are, the easier it is for a solvent such as water to penetrate, and the solid milk 10S can be dissolved faster. On the other hand, if the voids are too large, the hardness of the solid milk 10S may be weakened or the surface of the solid milk 10S may become rough. The dimensions (size) of each void are, for example, 10 μm to 500 μm. The dimensions (size) of each void and the distribution of the multiple voids can be measured by known means, such as observing the surface and cross section of the solid milk 10S using a scanning electron microscope. By such measurements, the porosity of the solid milk 10S can be determined.

[0027] The porosity of the solid milk 10S is, for example, 30% to 60%. The larger the porosity, the higher the solubility, but the lower the hardness (strength). Also, if the porosity is small, the solubility becomes poor. The porosity of the solid milk 10S is not limited to the range of 30% to 60%, and is appropriately adjusted depending on the application, etc.

[0028] The solid milk 10S preferably has a hardness in a predetermined range. The hardness can be measured by a known method. In this specification, the hardness is measured using a load cell type tablet hardness tester. The second surface 10B of the solid milk 10S having a rectangular parallelepiped shape is placed on the load cell type tablet hardness tester as the bottom surface, and fixed using one surface parallel to the XZ plane of the side surface 10C and one surface parallel to the YZ plane. The breaker terminal of the hardness tester is pressed at a constant speed in the short axis direction of the first surface 10A (Y axis direction in FIG. 1) in the direction in which the YZ plane becomes the fracture surface from the other surface side that is not fixed and parallel to the XZ plane of the side surface 10C, and the load [N] at which the solid milk 10S breaks is taken as the hardness (tablet hardness) [N] of the solid milk 10S. For example, a load cell type 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 breakable terminal is a rectangle of 1 mm x 24 mm, and the long side of the rectangle is arranged in a direction parallel to the Z-axis. The contact surface of the breakable terminal is configured to press the measurement point of the solid milk 10S at least in part. The speed at which the breakable terminal presses the solid milk 10S is 0.5 mm / s. The above-mentioned measurement of hardness is not limited to the solid milk 10S, but can also be applied to the measurement of the hardness of a compressed and molded product of milk powder (unhardened solid milk 10S) described below. Regarding the hardness measured as described above, in order to avoid the solid milk 10S being broken as much as possible when transporting the solid milk 10S, the hardness of the solid milk 10S is preferably 20N or more, more preferably 40N or more. On the other hand, if the hardness of the solid milk 10S is too high, the solubility of the solid milk 10S is deteriorated, so the hardness of the solid milk 10S is preferably 80N or less, more preferably 70N or less.

[0029] 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 at the time of this breakage 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 cross-sectional area at the time of breaking, and is an index that is independent of the dimensions of the solid milk sample, and allows comparison of the mechanical action acting on solid milk samples even between solid milk samples of different dimensions. For example, in the case of solid milk 10S, the ideal breaking cross-sectional area is expressed as the dimension b x c that results in the minimum breaking cross-sectional area of ​​the solid milk, and breaking stress = hardness / breaking cross-sectional area. For simplicity, hardness [N] is used for explanation in this specification, but these are also calculated as breaking stress [N / m 2 For example, if the solid milk 10S has an approximate shape of a rectangular parallelepiped with dimensions of 31 mm (a) × 24 mm (b) × 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 solid milk 10S, 20N or more and 100N or less, is determined by dividing the hardness by the cross-sectional area (300mm 2 ) to get 0.067N / mm 2 More than 0.33N / mm 2 This corresponds to a preferred breaking stress range of:

[0030] (Solubility) 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 the time it takes for the solid milk 10S to completely dissolve or the amount of undissolved solid milk 10S after a predetermined time when the solid milk 10S as a solute and water as a solvent are prepared to have a predetermined concentration.

[0031] Solid Milk 10S has superior solubility compared to conventional solid milk. The solubility can be measured as follows. The sample is placed in a stirring basket and submerged in warm water at 50°C. The volume of warm water is 200 ml per sample. When the weight of each sample is 4 to 6 g, the volume of warm water may be adjusted so that the solute concentration when the sample is used as the solute is in the range of 1.96% by weight to 2.91% by weight. The stirring basket containing the sample is rotated at a rotation speed of 0.5 ± 0.002 m / s (circumferential speed) to stir the warm water. The dissolution process from when the sample starts to dissolve until it is completely dissolved is measured over time using conductivity. The obtained conductivity is converted into dissolution rate. The dissolution rate at t seconds is defined as the ratio of conductivity when the conductivity at the end of dissolution is set to 100%. The time it takes for the dissolution rate of the sample to reach n% is called the n% dissolution time (t n The solubility at the initial stage of dissolution was measured as the 20% dissolution time (t 20 ), and the mid-dissolution period was 63% dissolution time (t 63 ), and the end of dissolution is the 95% dissolution time (t 95 The solubility index (I ) is an evaluation index that includes information on the initial, middle, and final dissolution times. d ) can be expressed by the following formula (1), and the smaller the value, the higher the solubility. I d =(t 20 / t 20ref +t 63 / t 63ref +t 95 / t 95ref ) / 3···(1)

[0032] In the above formula (1), t 20ref , t 63ref , and t 95refare the 20% dissolution time, 63% dissolution time, and 95% dissolution time of the reference solid milk, respectively, and are called reference values. The reference solid milk is solid milk prepared separately in the same manner as the solid milk of the embodiment, except that the conditions in the hardening treatment described later are different. The hardening conditions for preparing the reference solid milk are different from those for preparing the solid milk 10S in that the temperature of the humidification treatment is 100°C or less. The hardening treatment for forming the reference solid milk may further have different conditions for the drying treatment from those for preparing the solid milk 10S. The condition of the temperature of the humidification treatment being 100°C or less is a known condition, as described in the above Patent Document 2. The reference solid milk is a conventional solid milk in that the humidification treatment is performed under known conditions. The weight, shape, and hardness of the reference solid milk used in this embodiment are the same as those of the solid milk of the embodiment. Since the shape is the same, the surface area of ​​the reference solid milk is the same as that of the solid milk of the embodiment. The components of the reference solid milk are the same as those of the solid milk 10S. Alternatively, the reference solid milk may have at least the same composition of fat, protein, and carbohydrate as the solid milk 10S.

[0033] The weight, surface area, and hardness of the reference solid milk are not limited to the same as those of the solid milk of the embodiment. The weight of the reference solid milk includes a case where the difference from the solid milk of the embodiment is within ±0.3%. The surface area of ​​the reference solid milk includes a case where the difference from the solid milk of the embodiment is within ±2%. The hardness of the reference solid milk includes a case where the difference from the solid milk of the embodiment is within ±4%. If the difference in weight, surface area, and hardness of the reference solid milk is within the above ranges with respect to the solid milk of the embodiment, an appropriate reference value as a conventional solid milk can be obtained. The shape of the reference solid milk is selected according to the shape of the solid milk of the embodiment. For example, when the shape of the solid milk of the embodiment is a cylinder, an elliptical cylinder, a cube, a plate, a polygonal column, a polygonal truncated pyramid, or a polyhedron, the shape of the reference solid milk is a cylinder, an elliptical cylinder, a cube, a plate, a polygonal column, a polygonal truncated pyramid, or a polyhedron, respectively.

[0034] The hardness is adjusted by three conditions in the humidification treatment described below: temperature, humidity, and time. In the humidification treatment when preparing the reference solid milk, the environmental humidity is, for example, within a range of 60% RH to 100% RH, the humidification time is, for example, 5 seconds to 1 hour, and the temperature is, for example, 30° C. to 100° C. In the drying treatment when preparing the reference solid milk, the humidity is, for example, 0% RH to 30% RH, and the temperature is, for example, 20° C. to 150° C. A plurality of reference solid milks (for example, 10 pieces) are prepared, and the solubility of the plurality of reference solid milks is measured in the same manner as the solid milk of the above embodiment, and the arithmetic average of the obtained dissolution times is taken as a reference value (t 20ref , t 63ref , and t 95ref ) is used.

[0035] The dissolution times (t 20ref , t 63ref , and t 95ref ) to the dissolution time (t 20、 t 63、 t 95 ) proportion (t 20 / t 20ref , t 63 / t 63ref , t 95 / t 95ref ) to the relative elution time (Rt 20、 Rt 63、 Rt 95 The solubility index (I d ) is the relative elution time (Rt 20、 Rt 63、 Rt 95 The solubility index (I d The solubility index (I) is an index for evaluating the solubility of the solid milk of the embodiment, assuming that the solubility of a reference solid milk that differs only in the hardening treatment conditions is 1. d When the solubility index (I) of the solid milk in this embodiment is equal to or greater than 1, it indicates that the solubility is equal to or inferior to that of the reference solid milk. d ) is less than 1, so while it has the same hardness as conventional solid milk, it has superior solubility compared to conventional solid milk.

[0036] The solubility index (I d ) and the initial solubility is the 20% dissolution time (t 20 ), and the mid-dissolution period was 63% dissolution time (t 63 ), and the end of dissolution is the 95% dissolution time (t 95 ) is used to explain why.

[0037] Figure 3 is a graph showing the time-dependent change in dissolution rate of solid milk a and b produced under different conditions. The dissolution rate of solid milk a increases immediately after dissolution begins. The dissolution rate of solid milk b stagnates after the initial dissolution and then increases again.

[0038] 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 as indicators, but as shown in Figure 3, with solid milk, depending on the variety and manufacturing conditions, dissolution may stagnate at the beginning or it may take a long time to complete dissolution. Therefore, with solid milk, it is not appropriate to evaluate the solubility with an indicator of one or two points as with general tablets. In particular, an extension of the initial dissolution time is a factor that users perceive as "difficult to dissolve" in their sensory evaluation, and is important in evaluating the quality of solid milk.

[0039] The solubility index (I d In equation (1), which expresses the solubility index (I), the 20% dissolution time was used to evaluate the solubility in the early dissolution stage, the 63% dissolution time was used to evaluate the solubility in the middle dissolution stage, and the 95% dissolution time was used to evaluate the solubility in the late dissolution stage. The 63% dissolution time, which indicates the 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 the 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 In equation (1), the solubility index (I) is calculated as an index showing comprehensive solubility characteristics by taking the arithmetic average of the dissolution times of the initial, middle, and final stages of dissolution. d ) is defined as follows.

[0040] (Production method of solid milk 10S) 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 process for producing milk powder, for example, milk powder is produced through 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.

[0041] The liquid milk preparation step is a step of preparing liquid milk from the above ingredients.

[0042] The clarification process is a process for removing minute foreign matter contained in liquid milk. To remove the foreign matter, for example, a centrifuge or a filter may be used.

[0043] 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 actually considered to be contained vary depending on the type of liquid milk, the sterilization conditions (sterilization temperature and retention time) are appropriately set depending on the microorganism.

[0044] The homogenization process is a process for homogenizing liquid milk. Specifically, the particle size of solid components such as fat globules contained in 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 liquid milk, for example, the liquid milk may be passed through a narrow gap while being pressurized.

[0045] The concentration step is a step for concentrating liquid milk prior to the spray drying step described later. For example, a vacuum evaporator or an evaporator may be used to concentrate liquid milk. The concentration conditions are appropriately set within a range in which the components of the liquid milk are not excessively altered. This allows concentrated milk to be obtained from the liquid milk. In this embodiment, it is preferable to disperse gas in concentrated liquid milk (concentrated milk) and spray dry it. At this time, the moisture content of the concentrated milk is, for example, 35% by weight to 60% by weight, preferably 40% by weight to 60% by weight, and more preferably 40% by weight to 55% by weight. When gas is dispersed using such concentrated milk, the density of the liquid milk (concentrated milk) is reduced to increase the volume, and the concentrated milk in such a bulky state is spray-dried, whereby powdered milk having preferable characteristics can be obtained when producing solid milk. Note that when the moisture content of the liquid milk is low or when the amount of liquid milk to be treated in the spray drying step is small, this step may be omitted.

[0046] The gas dispersion process is a process for dispersing a predetermined gas in liquid milk (concentrated milk). At this time, the predetermined gas is, 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 More than double but less than three times.

[0047] In order to disperse the predetermined gas in the liquid milk, it is preferable to pressurize the predetermined gas. The pressure for pressurizing the predetermined gas is not particularly limited as long as it is within a range in which the gas can be effectively dispersed in the liquid milk, but the pressure of the predetermined gas can be, for example, 1.5 to 10 atm, preferably 2 to 5 atm. The liquid milk flows along a predetermined flow path to be sprayed in the following spray drying process, and in this gas dispersion process, 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 in the liquid milk.

[0048] In this way, the density of the liquid milk (concentrated milk) decreases and the apparent volume (bulk) increases by passing through 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. It may also be measured using a device for measuring density, such as a bulk density measurement in accordance with the JIS method (pigment: JISK5101 compliant).

[0049] Therefore, liquid milk in which a 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.

[0050] In this embodiment, carbon dioxide (carbonic acid 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, the percentage is also referred to as "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%. In this way, by controlling the volumetric flow rate of carbon dioxide to be constant relative to the volumetric flow rate of liquid milk, the uniformity of the powdered milk produced therefrom can be improved. However, if the CO2 mixing ratio is too large, the proportion of liquid milk flowing through the flow path decreases, and the production efficiency of powdered milk deteriorates. Therefore, the upper limit of the CO2 mixing ratio is preferably 700%. In addition, the pressure for pressurizing carbon dioxide is not particularly limited as long as it is within a range in which carbon dioxide can be effectively dispersed into liquid milk, but the atmospheric pressure of carbon dioxide can be, for example, 1.5 atm to 10 atm, and preferably 2 atm to 5 atm. 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).

[0051] In this embodiment, the predetermined gas used in the gas dispersion step is carbon dioxide gas. Instead of or together with carbon dioxide gas, one or more gases selected from the group consisting of air, nitrogen (N2), and oxygen (O2) may be used, or a rare gas (e.g., argon (Ar), helium (He)) may be used. In this way, various gases can be selected, and the gas dispersion step can be easily performed by using a gas that is easily available. In the gas dispersion step, when an inert gas such as nitrogen or a rare gas is used, there is no risk of reaction with the nutritional components of the liquid milk, and therefore it is preferable to use an inert gas such as nitrogen or a rare gas, as it 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 is, for example, 1% or more and 700% or less, preferably 1% or more and 500% or less, more preferably 1% or more and 400% or less, and most preferably 1% or more and 300% or less. For example, Bell et al. (RW BELL, FP HANRAHAN, BH WEBB: "FOAM SPRAY METHODS OF READILY DISPERSIBLE NONFAT DRY MILK", J. Dairy Sci, 46 (12) 1963. pp1352-1356) reported that in order to obtain skim milk powder, air was blown in at a volume about 18.7 times that of nonfat milk. In this embodiment, by dispersing the gas in the above range, milk powder having preferable properties for producing solid milk can be obtained. 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 a high solubility (water solubility) in water, and it is preferable to use a gas that is easily dispersed in liquid milk or that is easily dissolved in liquid milk. 3 Solubility in 0.1cm 3A gas having the above properties is preferable. 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 the cooled liquid milk, and as a result, milk powder having properties preferable for producing solid milk can be obtained.

[0052] The spray drying process is a process for evaporating water in liquid milk to obtain milk powder (powder). The milk powder obtained in this spray drying process is milk powder obtained through a gas dispersion process and a spray drying process. This milk powder is bulkier than milk powder obtained without the gas dispersion process. The former preferably has a volume 1.01 to 10 times that of the latter, but may also be 1.02 to 10 times, or 1.03 to 9 times.

[0053] In the spray drying process, the liquid milk is spray-dried while the density of the liquid milk is reduced by dispersing a predetermined gas in the liquid milk in the gas dispersion process. Specifically, it is preferable to perform spray drying in a state in which the volume of the liquid milk after the gas dispersion is 1.05 times or more and 3 times or less, preferably 1.1 times or more and 2 times or less, compared to the liquid milk before the gas dispersion. In other words, the spray drying process is performed after the gas dispersion process is completed. However, the liquid milk is not in a uniform state immediately after the gas dispersion process is completed. For this reason, the spray drying process is performed 0.1 seconds or more and 5 seconds or less, preferably 0.5 seconds or more and 3 seconds or less after the gas dispersion process is completed. In other words, it is sufficient that the gas dispersion process and the spray drying process are continuous. In this way, the liquid milk is continuously fed into the gas dispersion device to disperse the gas, and the liquid milk with the gas dispersed therein is continuously supplied to the spray drying device, and the spray drying can be continued.

[0054] In order to evaporate the moisture, a spray dryer (spray dryer) may be used. Here, the spray dryer has a flow path for flowing the liquid milk, a pressure pump for pressurizing the liquid milk to flow along the flow path, a drying chamber wider than the flow path connected to the opening of the flow path, and a spraying device (nozzle, atomizer, etc.) provided at the opening of the flow path. The spray dryer sends the liquid milk toward the drying chamber along the flow path with the pressure pump so as to achieve the above-mentioned volumetric flow rate, and in the vicinity of the opening of the flow path, the concentrated milk is diffused in the drying chamber with the spraying device, and the liquid milk in the droplet (atomized) state is dried at high temperature (for example, hot air) in the drying chamber. In other words, the moisture is removed by drying the liquid milk in the drying chamber, and as a result, the concentrated milk becomes a powdered solid, i.e., milk powder. In addition, by appropriately setting the drying conditions in the drying chamber, the moisture content of the milk powder, etc. is adjusted to make the milk powder less likely to aggregate. In addition, by using a spray device, the surface area per unit volume of the droplets is increased, improving the drying efficiency and at the same time adjusting the particle size of the powdered milk.

[0055] By going through the steps as described above, milk powder suitable for producing solid milk can be produced.

[0056] The milk powder obtained as described above is compressed and molded to form a compressed milk powder molded product. Next, the obtained compressed milk powder molded product is subjected to a hardening treatment including a humidifying treatment and a drying treatment. In this manner, solid milk 10S can be produced.

[0057] In the process of compressing and molding the milk powder, 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 equipped with a mortar that serves as a mold for putting the milk powder (powder) in, and a pestle that can be struck against the mortar. By putting the milk powder in the mortar (mold) and striking it with the pestle, compression pressure is applied to the milk powder, and a compressed and molded milk powder can be obtained. In the compression molding process, it is preferable to perform the compression work of the milk powder continuously.

[0058] In the process of compressing and molding the milk powder, the temperature of the environment is not particularly limited, and may be, for example, room temperature. Specifically, the temperature of the environment is, for example, 5°C to 35°C. The humidity of the environment is, for example, 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 control the compression pressure within the range of 1MPa to 30MPa so that the porosity is within the range of 30% to 60% and the hardness of the compressed and molded milk powder (before hardening) is within the range of 4N to 19N. This makes it possible to produce a highly practical solid milk 10S that combines solubility and convenience (ease of handling). The compressed and molded milk powder has a hardness (for example, 4N or more) that does not lose its shape at least in the subsequent humidification and drying processes. For example, when the approximate dimensions of the compressed milk powder molded product (before hardening) are the same as those of solid milk 10S, that is, a rectangular parallelepiped shape of 31 mm (a) × 24 mm (b) × 12.5 mm (c), the preferred hardness range of the compressed milk powder molded product (before hardening) of 4 N to 19 N is calculated by dividing the hardness by the cross-sectional area (300 mm 2 ) to get 0.013N / mm 2 More than 0.063N / mm 2 This corresponds to a preferred breaking stress range of:

[0059] The humidification process is a process of humidifying the compressed milk powder obtained in the compression molding process. When the compressed milk powder is humidified, tack (stickiness) occurs on the surface of the compressed milk powder. As a result, some of the powder particles near the surface of the compressed milk powder become liquid or gel-like, and crosslink with each other. When dried in this state, the strength near the surface of the compressed milk powder can be increased more than the strength inside. By adjusting the time (humidification time) to be placed in a high humidity environment (temperature, humidity), the degree of crosslinking (expansion) can be adjusted, and the hardness (for example, 4N to 19N) of the compressed milk powder (uncured solid milk 10S) before the humidification process can be increased to the desired hardness (for example, 40N) required for 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 molded product is not hard enough when it is transported on a belt conveyer or the like to moisten the compressed milk powder product after compression molding, the shape of the solid milk 10S cannot be maintained. Also, if the hardness of the compressed milk powder molded product is too high during compression molding, only solid milk 10S with low porosity and poor solubility can be obtained. For this reason, it is preferable to perform compression molding so that the hardness of the compressed milk powder molded product (unhardened solid milk 10S) before the moistening process is sufficiently high and the solubility of the solid milk 10S can be sufficiently maintained.

[0060] In the humidification treatment, the method of humidifying the compressed milk powder molded product is not particularly limited, and examples of the method 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.

[0061] When the compressed milk powder 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. The temperature when the compressed milk powder is placed in a high humidity environment 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 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 processing time when the compressed milk powder is placed in a high humidity environment is arbitrary, 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. Humidification conditions include temperature, humidity, and time. The higher the temperature, the higher the humidity, and the longer the time, the greater the humidification effect. Conversely, the lower the temperature, the lower the humidity, and the shorter the time, the weaker the humidification effect.

[0062] The reason for using a temperature environment above 100°C in the embodiment will be explained. As described in the above Patent Document 2, the conventional humidification drying method uses humidified air at 100°C or less. This is because the partial pressure of saturated water vapor under normal pressure (atmospheric pressure) is the same as normal pressure (atmospheric pressure) at 100°C, and therefore the temperature of water vapor under normal pressure will be 100°C or less unless special operations are performed. When considering actual production, processing in a sealed pressure vessel is required to create a high-pressure environment that is not normal pressure, and batch processing or the like reduces production efficiency, so it is desirable to be able to process continuously under a normal pressure environment.

[0063] Meanwhile, in recent drying techniques, superheated steam drying is also used, in which generated water vapor is heated by a heater or the like to a temperature above the boiling point (over 100°C under normal pressure) to produce "superheated steam". Superheated steam is used because of its high drying efficiency using thermal energy, and in this embodiment, this superheated steam is used in the humidification process. This makes it possible to use humidified air with humidity control of over 100°C (101°C or higher in the sense of being controlled) even under normal pressure. Specifically, the humidity can be adjusted by adjusting the amount of water vapor generated (input), and the temperature can be adjusted by the heat of the heater. In the actual humidification process, the hardness is adjusted by three conditions: temperature, humidity, and time.

[0064] The amount of water added to the compressed milk powder product in the humidification process of this embodiment (hereinafter also referred to as the "humidification amount") can be adjusted as appropriate. The humidification amount is preferably 0.5% by weight 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. If the humidification amount exceeds 3% by weight, the compressed milk powder product becomes excessively liquid or gel-like and dissolves, causing it to deform from the compressed and molded shape or to adhere to equipment such as a belt conveyor during transportation, which is not preferable.

[0065] The drying process is a process for drying the compressed milk powder that has been moistened by 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 are processes that increase the hardness of the compressed milk powder after compression molding, and impart the desired characteristics and quality to the solid milk 10S.

[0066] In the drying process, 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 process can be used. For example, there is a method of placing the compressed milk powder molded product in a low humidity and high temperature environment, a method of contacting the compressed milk powder molded product with dry air or high temperature dry air, etc.

[0067] When the compressed milk powder molded product is placed in a low humidity and 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 and high temperature environment is, for example, 330°C. The treatment time when the compressed milk powder molded product is placed in a low humidity and high temperature environment is arbitrary, but is, for example, 0.1 seconds or more and 100 seconds or less.

[0068] The above-mentioned humidification and drying processes can be carried out as separate processes under different temperature and humidity conditions, and in that case, they can be carried out continuously. The humidification and drying processes can also be carried out under the same temperature and humidity environment, and in this case, humidification and drying can be carried out simultaneously. For example, the compressed milk powder is placed in a first temperature and humidity environment in which humidification and drying occur simultaneously, and then placed in a second temperature and humidity environment in which only drying occurs. The period during which the first temperature and humidity is changed to the second temperature and humidity is the period during which the compressed milk powder is changed from a state in which humidification and drying occur simultaneously to a state in which only drying occurs.

[0069] However, if the solid milk 10S contains a large amount of water, it will have poor storage stability and will be prone to deterioration of flavor and discoloration. Therefore, in the drying process, 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 the raw material by controlling conditions such as the drying temperature and drying time.

[0070] The solid milk 10S thus produced 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 are poured in, or the solid milk 10S is poured in and then the warm water is poured in. The solid milk 10S is then quickly dissolved, preferably by shaking the container lightly, and consumed at an appropriate temperature. Preferably, one to several solid milk 10S (more preferably one solid milk 10S) is dissolved in warm water to produce the amount of liquid milk required for one drink, and the volume of the solid milk 10S is, for example, 1 cm. 3 ~50cm 3The volume of the solid milk 10S can be adjusted by changing the amount of powdered milk used in the compression molding process.

[0071] (Actions and Effects of the Solid Milk 10S Manufacturing Method) The method for producing the solid milk 10S of the present embodiment is to obtain a solubility index (I d ) is less than 1. In other words, it is possible to produce solid milk that has the same hardness as conventional solid milk but has excellent solubility. It is believed that the solubility of the solid milk 10S produced in this way is improved by setting the conditions for the humidification treatment for hardening to above 100°C. The solid milk 10S has suitable solubility and strength that makes it easy to handle, thereby making it more convenient. The solid milk 10S has a lower free fat content than conventional solid milk, and therefore oxidation can be further suppressed.

[0072] The reason why the solubility is improved by setting the humidification treatment condition for hardening to above 100°C is believed to be that when hardening treatment is performed at a humidification condition of above 100°C, a crosslinked structure formed by turning some of the powder particles into a liquid or gel state by humidification becomes a structure with higher solubility than the crosslinked structure formed by the conventional method of humidification treatment at below 100°C. More specifically, it is believed that a part of the powder particles near the surface of the compressed milk powder product softens by humidification at above 100°C, the sugars become in a non-crystalline rubber state, crosslinking occurs between adjacent particles at the contact points, and then the particles are dried to vitrify (solidify in a non-crystalline state), resulting in a structure with higher solubility.

[0073] <Application Examples> The above embodiment is solid milk obtained by compressing and molding milk powder, but the present invention can also be applied to solid foods formed by compressing and molding powder. For example, the present invention can be applied to solid foods compressed and molded using protein powders such as whey protein, soy protein, and collagen peptide, amino acid powder, and oil-containing powders such as MCT oil as raw materials. The solid foods according to the application examples have a solubility index (I d) is less than 1, the food has excellent solubility while having the same hardness as conventional solid foods. 20ref , t 63ref , and t 95ref is the time (seconds) at which the dissolution rate of a reference solid food formed under different hardening conditions from the solid food of the embodiment reaches 20%, 63%, and 95%. In addition to lactose or other carbohydrates, the raw material powder may contain nutritional components such as fat, protein, minerals, and vitamins, as well as food additives. The components of the reference solid food are the same as those of the solid food.

[0074] <Modification> 2 is a perspective view of solid milk 20S according to this modified example. Solid milk 20S has a solid body 20 obtained by compression molding milk powder. The body 20 has a first surface 20A that is flat and parallel to the XY plane, and a second surface 20B that is flat and parallel to the XY plane. The first surface 20A and the second surface 20B are back-to-back surfaces. The general shape of the body 20 is a rectangular parallelepiped, and the body 20 has a side surface 20C that is parallel to the XZ plane or the YZ plane.

[0075] The main body 20 is provided with two holes 21 that penetrate the main body 20 from the first surface 20A to the second surface 20B. The two holes 21 have the same elliptical shape in a cross section parallel to the XY plane. The size of the two holes 21 is selected so that the volume obtained by subtracting the total volume of the two holes 21 from the volume of the rectangular parallelepiped shape of the main body 20 is a predetermined value.

[0076] The positions of the two holes 21 are not significantly biased when viewed from the center of the first surface 20A. The two holes 21 are arranged in a direction parallel to the X-axis across the center of the first surface 20A, and the longitudinal direction of each hole 21 is parallel to the Y-axis. This arrangement is such that the two holes 21 are point-symmetric with respect to the center of the first surface 20A, or line-symmetric with respect to a line parallel to the X-axis or a line parallel to the Y-axis that passes through the center of the first surface 20A. If the interval between the two holes 21 is too narrow, the strength of that portion may not be maintained, so the interval is secured to a predetermined value or more. The same is true when viewed from the second surface 20B. The direction in which the holes 21 penetrate the main body 20 is a direction passing through the first surface 20A and the second surface 20B, and is, for example, a direction substantially parallel to the Z-axis.

[0077] The solid milk 20S can be manufactured in the same procedure as the manufacturing method of the present embodiment, except for the step of compressing and molding the milk powder. In the step of compressing and molding the milk powder, for example, the lower punch of the tablet press has a convex portion corresponding to the hole 21, and the upper punch has a concave portion corresponding to the convex portion, and the convex portion has a shape that can be inserted into the concave portion. By compressing and molding using such a punch, the hole 21 can be formed in the compressed milk powder product.

[0078] Since the solid milk 20S of this modified example has two holes 21, the reference solid milk also has a shape having two holes 21. In other words, the reference solid milk is solid milk of the same shape as the solid milk 20S having two holes 21 that is separately prepared, similar to the solid milk 20S of the modified example, except that the conditions for the hardening treatment are different. By making the reference solid milk the same as the solid milk 20S, except that the hardening treatment is different from that of the solid milk 20S, it is possible to apply the above formula (1) to the solid milk 20S. Therefore, the solubility index (I d ) is less than 1, it is possible to obtain the same effect as in the present embodiment, that is, while having the same hardness as conventional solid milk, it is more soluble than conventional solid milk.

[0079] The number of holes provided in the solid milk 20S is not limited to two, but may be, for example, one, four, or six.

[0080] <First Example> (Creation of working examples) A solid milk sample similar to the modified example shown in FIG. 2 was prepared as an example. The size of the main body of the solid milk was 31 mm in the X-axis direction, 24 mm in the Y-axis direction, and 12.5 mm in the Z-axis direction. The solid milk sample had a surface area of ​​2780 (mm 3 ), weight 5.4(g), volume excluding hole 21 is approximately 8250 mm 3 The size of the pestle and the compression pressure of the tablet press were adjusted to obtain this size, and the compressed milk powder was molded by compression molding. The conditions for molding the compressed milk powder were the same for all samples. The temperature of the humidification treatment was 130°C to 330°C, the humidity was 0.1% to 20%, and the treatment time was 5 to 10 seconds. The temperature of the drying treatment was 330°C, and the treatment time was 5 to 10 seconds. The hardness of the examples produced was 49N to 52N. Thus, all of the solid milks according to the examples had a hardness that was easy to handle.

[0081] (Creating a comparative example) A comparative example was prepared by preparing a solid milk sample in the same manner as in the example, except that the conditions for the hardening treatment were different. In the comparative example, the humidification temperature was 80°C, the humidity was 60% RH, and the treatment time was 30 seconds. The drying temperature was 80°C, and the treatment time was 360 seconds. The hardness of the comparative example was 51N.

[0082] (Solubility test) In order to evaluate the solubility depending on the curing conditions, a solubility test was performed on the solid milk samples of the examples and comparative examples prepared as described above. First, one solid milk sample was placed in the stirring basket. The stirring basket is a bottomed cylindrical container with a lid, with an inner diameter of 30 mm and a height of 36 mm, and has a side part, a bottom part, and a lid part. The side part, the bottom part, and the lid part are formed of a stainless steel net with an 18 mesh (1.01 mm mesh size). Four blades are evenly provided on the inner surface of the side part of the stirring basket. Each of the four blades is a plate with a thickness of 1.5 mm, a width of 4 mm, and a length of 34 mm, and is arranged so that the longitudinal direction is parallel to the central axis of the stirring basket and protrudes from the inner surface of the side part toward the center. The stirring basket was immersed in 200 ml of warm water (50±1° C.) contained in a 300 ml beaker, and the stirring basket was rotated at a rotation speed of 0.5 m / s (circumferential speed) while the solid milk sample was completely submerged. The stirring basket was held at a height of 5 mm from the inner bottom surface of the beaker. The dissolution process of the solid milk sample from when it started to dissolve until it was completely dissolved was measured at regular intervals by electrical conductivity.

[0083] 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 95 The 20% dissolution time, 63% dissolution time, and 95% dissolution time of the comparative example were compared with the reference value (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% elution time (t 63ref ) is 32 (seconds), and 95% dissolution time (t 95ref ) was 93 (seconds).

[0084] The results are shown in Figure 4. The vertical axis of Figure 4 is the solubility index (I d ), and the horizontal axis indicates the humidification temperature. Figure 4 shows the solubility index (I d4 is a graph showing the results of the experiments. In FIG. 4, solid black circles represent the examples, and white circles represent the comparative examples.

[0085] In FIG. 4, the solubility index (I d ) was smaller than 1.00, lower than that of the comparative example. This is thought to be due to the difference in the conditions of the hardening treatment, specifically, the temperature condition of the humidification treatment being over 100°C, and further the drying temperature being higher than that of the comparative example, and the treatment time being shorter, resulting in improved solubility.

[0086] (Free Fat Measurement Test) In order to evaluate the free fat content depending on the hardening conditions, the solid milk samples of the examples and comparative examples prepared as described above were measured for the free fat content. First, the solid milk was finely ground with a cutter, taking care not to crush it. The ground solid milk was then passed through a 32 mesh sieve. The solid milk that had passed through the sieving process was used as a sample, and the free fat content was measured 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 solvent for extraction was changed from carbon tetrachloride to n-hexane, and the extraction procedure was changed in accordance with this change in solvent. It has already been confirmed in "Study on Measuring Method of Free Fat in Powdered Milk" by Shibata Mitsuho, Hama Hatsumi, Imai Mami, and Toyoda Katsu, Nihon Shokuhin Kagaku Kougaku Kaishi Vol. 53, No. 10, 551-554 (2006) that the measurement results of free fat do not change even if these are changed. The results are shown in Figure 5. The vertical axis of Figure 5 indicates free fat, and the horizontal axis indicates humidification temperature. Figure 5 is a graph showing the free fat content against humidification temperature. The free fat content is the average value of two samples. In Figure 5, the filled black circles indicate working examples, and the open circles indicate comparative examples.

[0087] It was confirmed in Figure 5 that the free fat content was lower in all of the Examples than in the Comparative Examples. This is thought to be due to the difference in the conditions of the hardening treatment, specifically, the temperature condition of the humidification treatment being over 100°C, the drying temperature being higher than in the Comparative Examples, and the treatment time being shorter, which resulted in the lower free fat content.

[0088] <Second Example> The solid milk according to the embodiment was prepared in the same manner as in the first embodiment. The temperature of the humidification treatment was from over 100°C to 210°C, the relative humidity was from 2% (2% RH) to 20% (20% RH), and the treatment time was from 0.1 to 30 seconds. The temperature of the drying treatment was from over 100°C to 330°C, and the treatment time was from 5 to 20 seconds. The hardness of the prepared embodiment was 49N to 52N (the breaking stress at 50N was 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 the first embodiment and the comparative example described in the first embodiment. d ) was smaller than 1.00, lower than the Comparative Example. In addition, when the obtained solid milk was subjected to a free fat measurement test in the same manner as in the first example, it was confirmed that the free fat content was lower in all the Examples than in the Comparative Example.

[0089] Relative humidity can be measured with a commercially available hygrometer. For example, Vaisala's hygrometer HMT330 can be used up to 180°C, and Vaisala's dew point meter DMT345 can be used up to 350°C. Absolute humidity (volume absolute humidity (unit: g / m 3 ) or weight absolute humidity (units are kg / kg (DA), where DA is dry air) and convert it to relative humidity by calculating the ratio (%) of the water vapor partial pressure to the saturated water vapor pressure at that temperature. [Explanation of symbols]

[0090] 10. Main Unit 10A 1st side 10B 2nd side 10C side 10S solid milk

Claims

1. A method for producing a solid food product by compression molding food powder, comprising: A step of compressing and molding the food powder to form a food powder compression molded product; A step of subjecting the food powder compression molded product to a hardening treatment; having The hardening treatment is carried out by subjecting the compressed food powder product to a humidity of 100% RH or less and a temperature of 100° C. This involves a humidification process in which the material is placed in an environment with a temperature exceeding 100°C, followed by a drying process. The food powder is a material that generates tack on the surface when humidified at a temperature above 100°C. Methods for producing solid foods.

2. The food powder is selected from a protein powder, an amino acid powder, and an oil-containing powder. A method for producing the solid food product according to claim 1.

3. The humidification treatment is performed by placing the compressed food powder product in an environment with a temperature of 330°C or less. A method for producing the solid food according to claim 1 or 2.

4. The humidification treatment is performed by subjecting the compressed food powder product to an environment with a temperature of 130°C or higher and 210°C or lower. Put Down A method for producing the solid food according to any one of claims 1 to 3.

5. The humidification treatment is performed by subjecting the compressed food powder product to a humidity of 0.1% RH or more and 20% RH or less. Place in an environment of A method for producing the solid food according to any one of claims 1 to 4.

6. The humidification treatment is performed by subjecting the compressed food powder product to an environment of humidity of 1% RH or more and 15% RH or less. place under The method for producing the solid food according to any one of claims 1 to 5.

7. The drying process is performed by subjecting the compressed food powder product to a humidity of 0% RH or more and 30% RH or less. Place in an environment with a temperature between 80℃ and 330℃ A method for producing the solid food according to any one of claims 1 to 6.

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