Method for producing granular soybean milk powder, and granular soybean milk powder

Abstract

The present invention addresses the problem of providing a technique for producing soybean milk powder having excellent dispersibility and solubility. The present invention provides a method for producing a granular soybean milk powder, the method comprising: a concentration step for obtaining a concentrated soybean milk satisfying a predetermined condition from a raw soybean milk; and a drying step for obtaining a soybean milk powder from the concentrated soybean milk by spray granulation drying.

Description

Technical Field

[0001] The present invention relates to a method for producing granular soymilk powder and the granular soymilk powder. Background Art

[0002] Soy milk contains a large amount of protein and other nutrients, and is widely accepted by consumers as a beverage with high nutritional value.

[0003] On the other hand, from the viewpoint of improving the storage stability and circulation properties of soymilk, soymilk powder obtained by drying soymilk has been developed (for example, Patent Documents 1 to 3).

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Laid-Open No. 6-153841

[0007] Patent Document 2: Japanese Patent Application Laid-Open No. 2007-6835

[0008] Patent Document 3: Japanese Patent Application Laid-Open No. 2010-268781 Summary of the Invention

[0009] Technical problem to be solved by the invention

[0010] Here, soymilk powder is known to have problems such as low dispersibility and solubility and easy agglomeration when added to liquid (water, etc.).

[0011] In order to solve such a problem, attempts have been made to improve the dispersibility of soymilk powder by using excipients, as disclosed in Patent Documents 1 to 3.

[0012] However, the nutritional content (especially protein content) of soy milk powder mixed with excipients is reduced.

[0013] For example, when 10% by mass of an excipient is added to raw soy milk based on the solid content, the protein content of the resulting soy milk powder is approximately half that of a soy milk powder without the excipient.

[0014] Therefore, soy milk powder mixed with excipients has a poor function as a protein source.

[0015] Therefore, regardless of whether or not an excipient is used, a technology for obtaining a soymilk powder having excellent dispersibility and solubility is required.

[0016] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a technology for producing a soymilk powder having excellent dispersibility and solubility.

[0017] Solutions to Problems

[0018] The inventors of the present invention have discovered that, in the production process of soymilk powder, the above-mentioned problems can be solved by preparing concentrated soymilk that meets predetermined conditions from raw soymilk and drying the concentrated soymilk, thereby completing the present invention.

[0019] (1) A method for producing granular soymilk powder, characterized in that the method comprises:

[0020] A concentration step for obtaining concentrated soy milk from raw soy milk;

[0021] a drying step of obtaining soy milk powder from the concentrated soy milk by spray granulation drying,

[0022] The solid content concentration of the concentrated soy milk is 18% by mass or more,

[0023] The concentrated soy milk has a viscosity of 500 mPa·s or less at 20°C.

[0024] (2) A granular soymilk powder having an average particle size of 220 μm or more and 500 μm or less.

[0025] (3) The granular soymilk powder according to (1), wherein the particle size distribution of the granular soymilk powder satisfies all of the following:

[0026] D10 is 50 μm,

[0027] D50 is 250 μm,

[0028] D90 is 500μm.

[0029] (4) The granular soymilk powder according to (2), wherein the granular soymilk powder does not contain an excipient.

[0030] Effects of the Invention

[0031] According to the present invention, a technology for producing a soymilk powder having excellent dispersibility and solubility is provided. DETAILED DESCRIPTION

[0032] Hereinafter, embodiments of the present invention will be described in detail, but the present invention is not limited thereto.

[0033] <Method for producing granular soymilk powder>

[0034] The method for producing granular soymilk powder of the present invention (hereinafter also referred to as "the production method of the present invention") comprises: a concentration step of obtaining concentrated soymilk from raw soymilk; and a drying step of obtaining soymilk powder from the concentrated soymilk by spray granulation drying.

[0035] The solid content concentration of the concentrated soy milk is 18% by mass or more, and the viscosity of the concentrated soy milk is 500 mPa·s or less at 20°C.

[0036] Soy milk powder is usually obtained by spray-drying raw soy milk.

[0037] In addition, before spray drying, a concentration step is sometimes performed by heating the raw soy milk to partially evaporate its water content. This concentration step can reduce the volume of the raw soy milk and improve drying efficiency.

[0038] However, the present inventors have discovered that the conditions of the concentration step have a significant influence on the dispersibility and solubility of the obtained soymilk powder.

[0039] Specifically, it was found that if the soymilk protein is denatured during the concentration step, the dispersibility and solubility of the resulting soymilk powder are likely to deteriorate.

[0040] Furthermore, it was found that whether or not soymilk protein has been denatured is determined by the solid content concentration and viscosity of the concentrated soymilk obtained after the concentration step.

[0041] The present inventors conducted further studies and confirmed that when the solid content concentration of concentrated soy milk is 18% by mass or higher and the viscosity of the concentrated soy milk is 500 mPa·s or lower at 20°C, spray granulation drying can be performed well and the resulting dry powder has excellent dispersibility and solubility.

[0042] The present inventors have also found that the soymilk powder having excellent dispersibility and solubility is a granular soymilk powder having a predetermined average particle size.

[0043] (1) Definition

[0044] The definitions of terms commonly used in this invention are as follows:

[0045] In the present invention, "soy milk" includes a liquid obtained by soaking soybeans in water, grinding them, and filtering the juice after adding water to cook them.

[0046] In addition, the "soy milk powder" includes powders obtained by reducing the water content of soy milk.

[0047] In the present invention, the "dispersibility of soy milk powder" includes the fact that when the soy milk powder is added to a liquid (water, etc.), the soy milk powder easily sinks into the liquid and does not easily float to the surface of the liquid.

[0048] The dispersibility of soy milk powder can be evaluated by the method shown in the Examples.

[0049] In the present invention, the "solubility of soy milk powder" includes the fact that, when the soy milk powder is added to a liquid (water, etc.), the particle size distribution in the liquid is similar to the particle size distribution in the raw material soy milk.

[0050] The solubility of soy milk powder can be evaluated by the method shown in the Examples.

[0051] In the present invention, the "solid content concentration" refers to the ratio of solid content to liquid (soy milk, etc.) (unit: mass %), and can be measured using a microwave moisture analyzer.

[0052] In the present invention, "viscosity" refers to the viscosity coefficient of a substance (unit: Pa·s), which can be measured using a Brookfield viscometer. Unless otherwise specified, the viscosity in the present invention refers to a value at 20°C.

[0053] In the present invention, "granular powder" refers to aggregated particles formed by agglomeration of primary particles.

[0054] In one embodiment of the present invention, the granular soy milk powder is shaped like a bunch of grapes.

[0055] In the present invention, the "average particle size" is determined by laser diffraction methods using Fraunhofer diffraction theory and Mie scattering theory.

[0056] In the present invention, the average particle size has the same meaning as the particle size distribution D50 (median particle size).

[0057] In the present invention, "particle size distribution Dn is X μm" means that "n%" of the total particles have a particle size of "X μm or less".

[0058] For example, “D10 of the granular soymilk powder is 1 μm” means that 10% of the particles in the entire granular soymilk powder have a particle size of 1 μm or less.

[0059] In the present invention, the particle size distribution Dn is determined by laser diffraction methods using Fraunhofer diffraction theory and Mie scattering theory.

[0060] In the present invention, the "water content" refers to the amount of water contained in a substance (such as soy milk powder) (unit: mass %), and can be measured using an infrared moisture meter.

[0061] (2) Detailed description of the manufacturing method of the present invention

[0062] Hereinafter, each step of the production method of the present invention will be described in detail.

[0063] (2-1) Concentration process

[0064] The concentration process is a process of obtaining concentrated soy milk from raw soy milk.

[0065] (2-1-1) Raw material soy milk

[0066] The raw material soy milk is not particularly limited, and the same raw material soy milk as that used for conventional production of soy milk powder can be used.

[0067] However, in order to satisfy the viscosity requirement of concentrated soy milk described later, soy milk that has not been subjected to a process such as excessive heating to cause protein denaturation is used as the raw material.

[0068] From the viewpoint of easily exhibiting the effects of the present invention, the raw material soymilk is preferably soymilk whose solid content consists only of soybean-derived components, and more preferably unadjusted soymilk.

[0069] The solid content concentration of raw material soymilk is usually 9% by mass to 10% by mass.

[0070] The viscosity of raw soy milk is usually 2 to 3 mPa·s at 20°C.

[0071] (2-1-2) Conditions of the Concentration Process

[0072] In the concentration step, conditions are employed that can reduce the amount of water in the raw material soy milk and that are unlikely to cause denaturation of soy milk protein.

[0073] Whether or not soymilk protein has been denatured can be determined based on the appearance of the soymilk (gelation, etc.), the viscosity of the soymilk (whether or not it exceeds 500 mPa·s at 20° C., etc.), and the like.

[0074] From the viewpoint of easily suppressing denaturation of soymilk protein, the concentration step is preferably performed under vacuum conditions.

[0075] The degree of vacuum in the concentration step is not particularly limited as long as it can suppress denaturation of soymilk protein and achieve the desired solid content concentration of concentrated soymilk, but is generally 4 kPa to 20 kPa.

[0076] The temperature in the concentration step is adjusted according to the target solid content concentration of the concentrated soymilk and the degree of vacuum, and is usually 30°C to 70°C.

[0077] From the viewpoint of easily obtaining the desired concentrated soymilk, it is preferred to use a falling film evaporator in the concentration step.

[0078] The "falling film evaporator" is an apparatus that evaporates and concentrates a liquid substance (soy milk) while flowing down the heat transfer inner wall surface of a heat exchanger in the form of a liquid film.

[0079] When the concentration process is performed using a falling film evaporator, it is preferable to set the evaporation temperature of the raw soy milk under reduced pressure to be within the range of 40°C to 60°C, and the difference between the evaporation temperature and the heating steam side temperature to be within the range of 5°C to 15°C.

[0080] In the concentration step, the solid content concentration of the raw soy milk, the solid content concentration of the concentrated milk, and the viscosity are monitored, and the obtained concentrated soy milk is supplied to the drying step described below while maintaining the desired solid content concentration.

[0081] (2-1-3) Concentrated soy milk

[0082] The concentrated soymilk obtained after the concentration step has a solid content concentration of 18% by mass or more and a viscosity of 500 mPa·s or less at 20°C.

[0083] The lower limit of the solid content concentration of concentrated soymilk is 18% by mass or more, preferably 20% by mass or more.

[0084] From the viewpoint of suppressing an increase in viscosity, the upper limit of the solid content concentration of the concentrated soymilk is preferably 25% by mass or less, and more preferably 22% by mass or less.

[0085] The upper limit of the viscosity of concentrated soy milk is 500 mPa·s or less at 20°C, preferably 250 mPa·s or less, and more preferably 100 mPa·s or less.

[0086] The lower limit of the viscosity of concentrated soy milk is not particularly limited, but is usually 20 mPa·s or more at 20°C.

[0087] (2-2) Drying process

[0088] The drying step is a step of obtaining soymilk powder from concentrated soymilk by spray granulation drying.

[0089] The soymilk powder obtained after the drying step is the granular soymilk powder targeted by the present invention.

[0090] The spray granulation drying conditions may be any conditions that do not easily cause protein denaturation, can reduce the water content of the concentrated soymilk by spray drying, and can granulate the powder particles.

[0091] From the viewpoint of preventing protein denaturation, the drying conditions in the spray granulation drying are preferably such that the inlet temperature of the hot air used for drying is set to 120°C to 180°C, and the outlet temperature is set to 40°C to 90°C.

[0092] From the viewpoint of easiness in producing granular soymilk powder, it is preferable to use a fluidized granulation spray dryer for spray granulation drying.

[0093] The "fluidized bed granulation spray dryer" is a device that dries a liquid substance (soy milk) sprayed into a high-temperature airflow and granulates it using the fluidized bed granulation method.

[0094] The granular soymilk powder obtained after the drying process can be used directly, or can be stored, processed, etc.

[0095] (2-3) Other processes

[0096] Furthermore, the production method of the present invention may or may not include any steps that can be performed in a soymilk production method in addition to the above-mentioned steps, within a range that does not hinder the effects of the present invention.

[0097] The above steps can be performed at any time in the production method of the present invention depending on the purpose and the like.

[0098] Examples of the steps that may be included in the production method of the present invention include a heating step, a stirring step, a cooling step, an enzyme inactivation step of the raw soy milk, a soy milk powder packaging step, and a sterilization step.

[0099] (3) Granular soy milk powder

[0100] The present invention also includes granular soymilk powder obtained by the production method of the present invention.

[0101] The average particle size of the granulated soymilk powder of the present invention is 220 μm or more and 500 μm or less.

[0102] In conventional methods for producing soymilk powder, viscosity adjustment of concentrated soymilk before drying has not been sufficiently performed. Therefore, it has been difficult to obtain granular soymilk powder having the above-mentioned average particle size.

[0103] In the granulated soymilk powder of the present invention, the lower limit of the average particle size is 220 μm or more, preferably 250 μm or more.

[0104] In the granulated soymilk powder of the present invention, the upper limit of the average particle size is 500 μm or less, preferably 300 μm or less.

[0105] The particle size distribution (Dn) of the granular soymilk powder of the present invention is not particularly limited, and may satisfy any or all of the following conditions from the viewpoint of easily obtaining a uniform granular soymilk powder.

[0106] D10 is preferably 100 μm, more preferably 80 μm, and further preferably 50 μm.

[0107] D50 is preferably 500 μm, more preferably 300 μm, and further preferably 250 μm.

[0108] D90 is preferably 2000 μm, more preferably 1000 μm, and further preferably 500 μm.

[0109] The granular soymilk powder of the present invention has good dispersibility and solubility.

[0110] In a preferred embodiment of the present invention, the granular soymilk powder of the present invention has an average particle size of 0.5 μm or more and 1.5 μm or less when dissolved in water. Conventional soymilk powders tend to clump when added to water, making it difficult to achieve such a small average particle size in water.

[0111] In the above description, the temperature of the water in which the granular soymilk powder is dissolved is not particularly limited, but is preferably 20°C to 80°C, and more preferably 50°C to 60°C. The average particle size may be measured directly after dissolving the granular soymilk powder in water, or may be measured after cooling the water to approximately 4°C to 20°C.

[0112] The granular soymilk powder of the present invention is not particularly limited as long as it is in a sufficiently dry state.

[0113] The water content of the granulated soymilk powder of the present invention is preferably 5.0% by mass or less, more preferably 4.5% by mass or less.

[0114] The granular soymilk powder of the present invention is an aggregated granule formed by agglomeration of primary particles.

[0115] As described above, the average particle size of the aggregated particles is 220 μm or more and 500 μm or less.

[0116] The average particle size of the primary particles constituting the aggregated particles is not particularly limited, but is preferably 30 μm to 60 μm.

[0117] The granular soymilk powder of the present invention may or may not contain any of the components that are incorporated into conventional soymilk powders.

[0118] Examples of such components include excipients, stabilizers, emulsifiers, thickeners, etc. The types and amounts of these components can be appropriately adjusted depending on the desired effects.

[0119] Furthermore, the above-mentioned components may be components that are blended together with the raw material soy milk as raw materials when producing the granular soy milk powder.

[0120] Conventionally, to improve the dispersibility and solubility of soymilk powder, excipients have been added to soymilk powder raw materials, as described in Patent Documents 1 to 3. Examples of excipients include sugars (monosaccharides, oligosaccharides, and polysaccharides, as well as chemically treated products thereof) and proteins derived from sources other than soybeans (such as collagen).

[0121] On the other hand, the granulated soymilk powder according to the present invention has excellent dispersibility and solubility regardless of the presence or absence of excipients.

[0122] Therefore, in a preferred embodiment of the present invention, the granular soymilk powder does not contain an excipient. However, the present invention does not exclude the possibility that the granular soymilk powder contains an excipient.

[0123] When the granular soymilk powder of the present invention contains an excipient, the content thereof is preferably an amount that does not function as an excipient or an amount that does not impair the function of the granular soymilk powder as a protein source.

[0124] The amount of excipients permitted by the above viewpoint is preferably 5% by mass or less, and more preferably 1% by mass or less, relative to the raw material soy milk. In this case, the granulated soy milk powder obtained from the raw material soy milk can contain preferably 33.3% by mass or less, and more preferably 9.1% by mass or less of excipients.

[0125] The application of the granular soymilk powder of the present invention is not particularly limited, and the granular soymilk powder can be used in various applications similar to conventional soymilk powders.

[0126] Example

[0127] Hereinafter, the present invention will be described in further detail using examples, but the present invention is not limited to these examples.

[0128] <Production of Soy Milk Powder>

[0129] Granular soy milk powder (composed only of ingredients derived from raw soy milk) was prepared by the following method.

[0130] As a "reference example", commercially available soy milk powder was also prepared.

[0131] (1) Concentration process

[0132] As raw material soy milk, commercially available soy milk (solid content concentration = about 9 mass %) was prepared.

[0133] The raw soy milk was concentrated under vacuum conditions by a falling film evaporator.

[0134] The vacuum conditions are set so that the evaporation temperature of the raw soybean milk under reduced pressure is within the range of 40°C to 60°C, and the difference between the evaporation temperature and the heating steam side temperature is within the range of 5°C to 15°C.

[0135] During the concentration process, the solids concentration and viscosity of the raw soy milk were monitored. The concentration process was completed when the solids concentration of the raw soy milk reached 18% to 22% by mass. The resulting soy milk was recovered as concentrated soy milk and fed to the drying process. The viscosity of the concentrated soy milk (at 20°C) at the time of the drying process was 250 mPa·s.

[0136] Furthermore, as "Comparative Example-1", soymilk that had not been subjected to the concentration step (raw material soymilk itself) was also subjected to the drying step.

[0137] (2) Drying process

[0138] The concentrated soymilk was spray-granulated and dried using a fluidized granulation spray dryer, thereby drying and granulating the concentrated soymilk to obtain granular soymilk powder.

[0139] Furthermore, as "Comparative Example 2", a soymilk powder (commercially available, non-granular) dried using a single-stage spray dryer and a drum dryer was obtained.

[0140] <Evaluation of Granular Soymilk Powder>

[0141] The obtained soymilk powder was subjected to the following various evaluations.

[0142] (1) Average particle size and particle size distribution (Dn)

[0143] The average particle size of each soymilk powder was measured by laser diffraction / scattering methods using Fraunhofer diffraction theory and Mie scattering theory. "Mastersizer 3000" (manufactured by Malvern Panalytical) was used for the measurement.

[0144] The average particle size was measured at 20° C. for the following objects: a dry method was used when the object was a powder, and a wet method was used when the object was an aqueous solution.

[0145] ·Soy milk powder

[0146] 7% by mass aqueous solution of each soymilk powder

[0147] (2) Moisture content

[0148] The water content of each soymilk powder was measured using an infrared moisture meter "FD-720" (manufactured by Kettle Scientific Laboratory Co., Ltd.).

[0149] (3) Dispersibility

[0150] MilliQ water (300 g) was placed in a 500 ml stainless steel can and kept warm at 60°C.

[0151] Next, each soymilk powder (25 g) was added while stirring with a homomixer (5,000 rpm), and the dispersion time (unit: seconds) until the entire amount sank was measured.

[0152] The shorter the dispersion time, the better the dispersibility.

[0153] (4) Solubility

[0154] As in the above-mentioned "dispersibility" item, each soymilk powder was added to warm MilliQ water and stirred to obtain an aqueous solution of each soymilk powder.

[0155] The particle size distribution of each aqueous solution was determined, compared with the particle size distribution of the raw soy milk, and evaluated according to the following criteria. It should be noted that the similarity of the particle size distributions was determined based on the position and size of the peaks.

[0156] A: The particle size distribution is similar to that of the raw soy milk

[0157] B: The particle size distribution is different from that in the raw soy milk.

[0158] <Results>

[0159] The results are shown in the table.

[0160] The granular soymilk powder ("Example") obtained by the production method of the present invention has remarkably excellent dispersibility and solubility.

[0161] Furthermore, the average particle size of the granular soymilk powder obtained by the production method of the present invention is stably within the range of 220 μm to 300 μm.

[0162] It should be noted that, according to a particle size distribution analysis, it was confirmed that the average particle size of primary particles of the granular soymilk powder was approximately 50 μm.

[0163] On the other hand, when the concentration step was not performed (Comparative Example 1), granular soymilk powder could not be stably obtained. In addition, the obtained powder had extremely low dispersibility, formed large lumps (agglomerates) in aqueous solution, and had reduced solubility.

[0164] Although data are not shown, even with a high solids concentration, concentrated soymilk can be spray-granulated and dried satisfactorily as long as the viscosity (20°C) is 500 mPa·s or less. Furthermore, by satisfying all the requirements for the concentrated soymilk of the present invention, protein denaturation (which affects gelation, etc.) in the soymilk is suppressed, resulting in a granular soymilk powder with excellent dispersibility and solubility.

[0165] On the other hand, when the viscosity (20°C) exceeds 500 mPa·s, the protein in the soy milk is easily denatured regardless of the solid content concentration of the concentrated soy milk, making spray granulation drying difficult and only resulting in a powder with poor dispersibility and solubility.

[0166] This demonstrates that suppressing protein denaturation during the concentration process is crucial for obtaining granular soymilk powder with excellent dispersibility and solubility. Furthermore, the significance of the solids concentration and viscosity of concentrated soymilk as indicators of this denaturation suppression has become clear.

[0167] [Table 1]

[0168]

Claims

1. A method for producing granular soymilk powder, characterized in that: The manufacturing method comprises: A concentration step for obtaining concentrated soy milk from raw soy milk; a drying step of obtaining soy milk powder from the concentrated soy milk by spray granulation drying, The solid content concentration of the concentrated soy milk is 18% by mass or more, The concentrated soy milk has a viscosity of 500 mPa·s or less at 20°C.

2. A granular soy milk powder, wherein: The average particle size is 220 μm or more and 500 μm or less.

3. The granular soy milk powder according to claim 1, wherein The particle size distribution of the granular soy milk powder satisfies all of the following: D10 is 50 μm, D50 is 250μm, D90 is 500 μm.

4. The granular soy milk powder according to claim 2, wherein The granular soy milk powder does not contain excipients.

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