Method for manufacturing processed rice flour having improved dispersion stability

Abstract

The present invention relates to a method for manufacturing processed rice flour having improved dispersion stability and a low degree of sedimentation. Particularly, an aqueous solution obtained by hydrating processed rice flour manufactured by the manufacturing method maintains turbidity and dispersion stability, and does not form precipitates, even with prolonged storage time. Therefore, the processed rice flour manufactured by the present invention can be usefully used as a material for foods, including rice beverages.

Description

Method for manufacturing rice flour with improved dispersion stability

[0001] Cross-reference to related applications

[0002] This disclosure claims priority to patent application Ser. No. 10-2023-0166127, filed November 24, 2023, the entire contents of which are incorporated herein by reference.

[0003] Technology field

[0004] The present invention relates to a method for producing rice flour for use as a food raw material, and more particularly, to a method for producing rice flour, which includes improving the dispersion stability of rice flour by performing ultrasonic treatment so as to exhibit low viscosity and prevent sedimentation when rice flour is hydrated.

[0005] Rice is a staple food passed down through generations, forming the foundation of our diet. The edible portion of rice is mostly starch, accounting for approximately 75% to 80%, with protein accounting for 6% to 8%, and fat, fiber, and ash each accounting for 1% to 3%. It also contains minerals such as phosphorus, potassium, calcium, magnesium, sodium, and iron. It is also rich in the B complex vitamins, including vitamins B1 and B2, and the essential amino acid lysine, making it highly nutritionally valuable.

[0006] Recently, various functional ingredients contained in rice have been receiving attention. Hemicellulose and beta-glucan, which make up the dietary fiber of rice, have been reported to lower cholesterol and suppress the incidence of colon cancer. Tocopherol and tocotrienol have antioxidant, anti-aging, and anti-inflammatory effects. Gamma-oryzanol is known to promote growth, regulate liver function, and improve menopausal disorders.

[0007] Therefore, in order to make rice consumption easier and increase consumption, in the past, processed foods such as rice cakes, instant rice, porridge, noodles, or rice crackers or rice flour as a substitute for wheat flour were mainly developed, and alcoholic beverages such as makgeolli and cheongju were the mainstream.

[0008] While beverages made from rice are available on the market, they suffer from problems such as poor dispersion stability of the rice flour and sedimentation. Rice flour is insoluble, and when gelatinized in water, it forms a gel and tends to settle, limiting its use as a beverage ingredient. Therefore, further processing is essential for rice flour to be used in beverages.

[0009] As a prior art document on a beverage containing rice flour, Korean Patent No. 10-1045100 discloses a method for manufacturing a rice beverage including the processes of washing, steaming and liquefying rice, saccharification, enzyme inactivation, homogenization, ultrafine particle formation, and sterilization, and provides a method for manufacturing a rice beverage formulation that allows consumption of all the nutritional components of rice, including nutrient-rich rice bran (rice germ) components, without separately adding other ingredients such as emulsifiers or emulsification stabilizers other than rice. In addition, Korean Patent No. 10-0294821 discloses a process for manufacturing a rice beverage by roasting and pulverizing white rice or brown rice to impart flavor, then liquefying and saccharifying the rice using an enzyme, filtering the rice to obtain a clear and clean purified liquid, and adding sucrose fatty acid ester to the purified liquid to emulsify and homogenize the rice. In addition, Korean Patent No. 10-2131710 discloses a method for producing blended tea using rice milk, specifically, preparing rice milk and tea syrup separately and then mixing them by stirring, preparing the rice milk by soaking rice in purified water, and then adding salt, maple syrup, and natural vanilla extract to the soaked rice to form a first mixture, which is then ground and mixed using a mixer, and in the above-described grinding and mixing step, brown rice oil and rice bran extract powder as an emulsifier are further added to the first mixture, and ultrasonic waves are focused to disperse the particles of the first mixture.

[0010] As described above, in order to maintain the dispersion stability of rice beverages containing rice flour and prevent the rice flour from settling, methods such as performing complex processes or treating emulsifiers have been reported. In order to supplement the above-mentioned problems and to materialize rice flour for application to rice beverages, the inventors of the present invention have devised a method for producing rice flour that can reduce costs through a simple process and improve the dispersion stability of a gelatinized rice flour aqueous solution without treating an emulsifier, thereby achieving a high recovery rate of dispersibility upon rehydration.

[0011] The purpose of the present invention is to provide a method for producing rice flour having improved dispersion stability and low sedimentation rate in an aqueous solution.

[0012] Another object of the present invention is to provide rice flour having improved dispersion stability and low sedimentation rate in an aqueous solution manufactured by the above manufacturing method.

[0013] Another object of the present invention is to provide a rice beverage manufactured using rice flour having improved dispersion stability and a high degree of rehydration.

[0014] To achieve the above purpose,

[0015] The present invention

[0016] (1) A step of preparing a slurry by mixing rice flour into water;

[0017] (2) A step of preparing a rice flour gelatin solution by stirring the prepared slurry while applying heat;

[0018] (3) Step of cooling the manufactured rice flour gelatin solution;

[0019] (4) Step of ultrasonic treatment of the cooled rice flour gelatin solution; and

[0020] (5) A method for manufacturing rice flour with improved dispersion stability and low sedimentation rate is provided, including a step of homogenizing and drying a rice flour gelatin solution treated with ultrasound.

[0021] In addition, the present invention provides a food product including rice flour with improved dispersion stability and low sedimentation rate manufactured through the above-described method for manufacturing rice flour, and a rice beverage using the same.

[0022] The present invention provides a method for producing rice flour with improved dispersion stability and low sedimentation, and specifically, an aqueous solution of rice flour produced by the above-described method has the effect of maintaining turbidity and dispersion stability and preventing sedimentation even after a long storage period, so that the rice flour produced by the present invention can be usefully used as a material for food products including rice beverages.

[0023] Figure 1 is a photograph showing the flow characteristics when the regular rice flour of Comparative Example 1 or the gelatinized rice flour of Comparative Example 2 was mixed in water and then stored.

[0024] Figure 2 is a diagram showing the cumulative particle size distribution, density distribution, and major indices of general rice flour ground by the air-flow grinder of Comparative Example 1.

[0025] Figure 3a is a photograph showing the appearance of a rice flour suspension of Comparative Example 1 having a particle size of more than 150 ㎛, more than 125 ㎛, more than 100 ㎛, more than 75 ㎛, more than 50 ㎛, and less than 50 ㎛ (U) after being stored for one day.

[0026] Figure 3b is a diagram showing the normalized absorption (abs) of the rice flour suspension according to the rice flour particle size of Comparative Example 1.

[0027] Figure 4 is a diagram showing a rapid viscoanalyzer (RVA) curve according to the particle size of the luxurious rice flour of Comparative Example 2.

[0028] Figure 5 is a diagram showing the composite viscosity according to the particle size of the luxurious rice flour of Comparative Example 2.

[0029] Figure 6 is a photograph showing the flow characteristics of an ultrasonically treated rice flour aqueous solution (Example 1) and an ultrasonically untreated rice flour aqueous solution (Comparative Example 2).

[0030] Figure 7a is a photograph comparing the dispersion stability of a suspension of gelatinized rice flour when stored for 7 days for regular rice flour (F, Comparative Example 1), gelatinized rice flour (0T), and gelatinized rice flour (Example 1) treated with ultrasound for 3 minutes (3T), 6 minutes (6T), 9 minutes (9T), 12 minutes (12T), and 15 minutes (15T).

[0031] Figure 7b is a diagram showing the normalized absorption (abs) of suspensions of regular rice flour (F, Comparative Example 1) and gelatinized rice flour (Example 1) treated with ultrasonic treatment times (3T, 6T, 9T, 12T, and 15T).

[0032] Figure 8a is a diagram showing the Rapid Visco Analyzer (RVA) curves for rice flour suspensions according to the sonication time (3T, 6T, 9T, 12T, and 15T), without sonication (F, Comparative Example 1), and without sonication (0T, Comparative Example 2).

[0033] Figure 8b is an enlarged view of the Rapid Visco Analyzer (RVA) curves for the rice flour suspension according to the sonication time (3T, 6T, 9T, 12T, and 15T) in Figure 8a.

[0034] Figure 9a is a diagram showing the storage modulus-loss modulus of rice flour according to the time of normal rice flour (F, Comparative Example 1), no ultrasonic treatment (0T, Comparative Example 2), and ultrasonic treatment (3T, 6T, 9T, 12T, and 15T).

[0035] Figure 9b is a diagram showing the complex viscosity of rice flour according to the time of normal rice flour (F, Comparative Example 1), no ultrasonic treatment (0T, Comparative Example 2), and ultrasonic treatment (3T, 6T, 9T, 12T, and 15T).

[0036] Figure 10 is a diagram showing SEM images (X 2,500) of ultrasonic-treated gelatinized rice flour powder. a: gelatinized rice flour, b to f: ultrasonic-treated gelatinized rice flour (b: 3 minutes, c: 6 minutes, d: 9 minutes, e: 12 minutes, f: 15 minutes)

[0037] Hereinafter, the present invention will be described in detail.

[0038] The present invention

[0039] (1) A step of preparing a slurry by mixing rice flour into water;

[0040] (2) A step of preparing a rice flour gelatin solution by stirring the prepared slurry while applying heat;

[0041] (3) Step of cooling the manufactured rice flour gelatin solution;

[0042] (4) Step of ultrasonic treatment of the cooled rice flour gelatin solution; and

[0043] (5) A method for producing rice flour with improved dispersion stability is provided, including a step of homogenizing and drying a rice flour gelatin solution treated with ultrasound.

[0044] The term "dispersion stability" as used herein means that the rice flour aqueous solution or suspension obtained by hydrating rice flour in water exhibits no change in turbidity and no sedimentation, with rice flour particles being uniformly distributed throughout the aqueous solution. Furthermore, it means that the manufactured rice flour, when rehydrated, has a high degree of rehydration, a high rate of recovery in dispersibility, and a low rate of sedimentation of the rice flour in the aqueous solution.

[0045] In a specific embodiment of the present invention, the mixing ratio of water and rice flour in step (1) may be 3:1 (25%) to 19:1 (5%) based on weight, and may be 4:1 to 18:1, 5:1 to 16:1, 6:1 to 14:1, or 7:1 to 12:1, but preferably, may be 8:1 to 10:1.

[0046] A mixing ratio of water and rice flour of the above step (1) of less than 3:1 results in too high a ratio of rice flour, forming a slurry with high viscosity, making it difficult to apply to subsequent processes. A ratio of more than 19:1 is not suitable because the yield of rice flour after the final step is low.

[0047] In addition, in a specific embodiment of the present invention, a completely gelatinized rice flour gelatin solution can be prepared by applying heat and stirring in the step (2). There is no limitation on the method for completely gelatinizing the rice flour gelatin solution, and preferably, heating can be performed at a temperature of 70 to 100°C for 30 to 120 minutes. Specifically, the temperature can be 70°C or higher, 72°C or higher, 74°C or higher, 76°C or higher, 78°C or higher, 80°C or higher, 82°C or higher, 84°C or higher, 86°C or higher, 87°C or higher, 88°C or higher, 89°C or higher, 90°C or higher, 91°C or higher, 92°C or higher, 93°C or higher, 94°C or higher, 95°C or higher, 96°C or higher, 97°C or higher, 98°C or higher, or 99°C or higher. Additionally, the temperature may be 100°C or less, 98°C or less, 96°C or less, 94°C or less, 92°C or less, 90°C or less, 88°C or less, 86°C or less, 84°C or less, 83°C or less, 82°C or less, 81°C or less, 80°C or less, 79°C or less, 78°C or less, 77°C or less, 76°C or less, 75°C or less, 74°C or less, 73°C or less, 72°C or less, or 71°C or less.

[0048] Specifically, the time may be 30 minutes or more, 33 minutes or more, 36 minutes or more, 39 minutes or more, 42 minutes or more, 45 minutes or more, 48 minutes or more, 51 minutes or more, 54 minutes or more, 57 minutes or more, 60 minutes or more, 63 minutes or more, 66 minutes or more, 69 minutes or more, 72 minutes or more, 75 minutes or more, 78 minutes or more, 81 minutes or more, 84 minutes or more, 87 minutes or more, 90 minutes or more, 93 minutes or more, 96 minutes or more, 99 minutes or more, 102 minutes or more, 105 minutes or more, 108 minutes or more, 111 minutes or more, 114 minutes or more, 117 minutes or more, or 119 minutes or more. Additionally, the time may be 120 minutes or less, 117 minutes or less, 113 minutes or less, 110 minutes or less, 107 minutes or less, 104 minutes or less, 101 minutes or less, 98 minutes or less, 95 minutes or less, 92 minutes or less, 89 minutes or less, 86 minutes or less, 83 minutes or less, 80 minutes or less, 77 minutes or less, 74 minutes or less, 71 minutes or less, 68 minutes or less, 65 minutes or less, 62 minutes or less, 59 minutes or less, 56 minutes or less, 53 minutes or less, 50 minutes or less, 47 minutes or less, 44 minutes or less, 41 minutes or less, 38 minutes or less, 36 minutes or less, 33 minutes or less, or 31 minutes or less.

[0049] In the above step (2), at temperatures below 70°C, the rice flour does not gelatinize properly, and at temperatures above 100°C, excessive heat is applied, resulting in no energy benefit. At times below 30 minutes, the rice flour does not gelatinize properly, and at times above 120 minutes, there is no energy benefit.

[0050] In addition, in a specific embodiment of the present invention, cooling may be performed at a temperature of 15 to 35°C in step (3). Specifically, the temperature may be 15°C or higher, 16°C or higher, 17°C or higher, 18°C ​​or higher, 19°C or higher, 20°C or higher, 21°C or higher, 22°C or higher, 23°C or higher, 24°C or higher, 25°C or higher, 26°C or higher, 27°C or higher, 28°C or higher, 29°C or higher, 30°C or higher, 31°C or higher, 32°C or higher, 33°C or higher, or 34°C or higher. Additionally, the temperature may be 35°C or less, 34°C or less, 33°C or less, 32°C or less, 31°C or less, 30°C or less, 29°C or less, 28°C or less, 27°C or less, 26°C or less, 25°C or less, 24°C or less, 23°C or less, 22°C or less, 21°C or less, 20°C or less, 19°C or less, 18°C ​​or less, 17°C or less, or 16°C or less.

[0051] In the above step (3), at a temperature below 15°C, the viscosity of the rice gelatinization gel becomes too high, making it difficult to apply subsequent processes, and at a temperature above 35°C, there is a possibility that the sample will reach a temperature at which a thermal change occurs due to the heat generated by the subsequent ultrasonic treatment.

[0052] In addition, in a specific embodiment of the present invention, the ultrasonic treatment in step (4) may be performed for 1 to 60 minutes. Specifically, the time may be 1 minute or more, 2 minutes or more, 3 minutes or more, 4 minutes or more, 5 minutes or more, 6 minutes or more, 7 minutes or more, 8 minutes or more, 9 minutes or more, 10 minutes or more, 11 minutes or more, 12 minutes or more, 13 minutes or more, 14 minutes or more, 15 minutes or more, 16 minutes or more, 17 minutes or more, 18 minutes or more, 19 minutes or more, 20 minutes or more, 22 minutes or more, 24 minutes or more, 26 minutes or more, 28 minutes or more, 29 minutes or more, 32 minutes or more, 35 minutes or more, 38 minutes or more, 41 minutes or more, 44 minutes or more, 47 minutes or more, 50 minutes or more, 53 minutes or more, 56 minutes or more, or 59 minutes or more. Additionally, the time may be 60 minutes or less, 57 minutes or less, 54 minutes or less, 51 minutes or less, 48 ​​minutes or less, 45 minutes or less, 42 minutes or less, 39 minutes or less, 36 minutes or less, 33 minutes or less, 30 minutes or less, 29 minutes or less, 28 minutes or less, 27 minutes or less, 26 minutes or less, 25 minutes or less, 24 minutes or less, 23 minutes or less, 22 minutes or less, 21 minutes or less, 20 minutes or less, 19 minutes or less, 18 minutes or less, 17 minutes or less, 16 minutes or less, 15 minutes or less, 14 minutes or less, 13 minutes or less, 12 minutes or less, 11 minutes or less, 10 minutes or less, 9 minutes or less, 8 minutes or less, 7 minutes or less, 6 minutes or less, 5 minutes or less, 4 minutes or less, 3 minutes or less, or 2 minutes or less.

[0053] In the above step (4), ultrasonic treatment can be performed for 1 to 60 minutes. If the ultrasonic treatment is performed for less than 1 minute, the effect of ultrasonic treatment is weak and the desired properties of the rice gelatinized gel cannot be obtained, and if the ultrasonic treatment is performed for more than 60 minutes, there is no energy efficiency compared to the effect.

[0054] In addition, in a specific embodiment of the present invention, the drying method in the step (5) is not particularly limited, and a drying method commonly used in the technical field to which the present invention belongs can be used, and specifically, any method applicable to food such as hot air drying, freeze drying, spray drying, vacuum drying, drum drying, low-temperature drying, freeze drying, vacuum freeze drying, microwave drying, or pressure drying can be used.

[0055] The rice flour obtained through the above step (5) of the present invention has the characteristic that no sedimentation or change in turbidity occurs with increasing storage period after hydration in water (Experimental Example 2-2).

[0056] It was confirmed that the rice flour obtained through step (5) of the present invention maintained dispersion stability and had low sedimentation when hydrated in water (Experimental Example 2-2).

[0057] In addition, it was confirmed that the starch solubility (water solubility, WS%) of the rice flour solution obtained through step (5) increased compared to that of the unultrasonic-treated rice flour, and that the starch solubility was very high (Experimental Example 2-3).

[0058] The rice flour obtained through step (5) of the present invention had a reduced viscosity when hydrated in water compared to rice flour not treated with ultrasound. Specifically, the final viscosity of the non-ultrasonic treatment group was recorded at 154.66 RVU, but when ultrasonic treatment was performed for 3, 6, 9, 12, and 15 minutes, it showed a very low value of 4.42 to 13.28 RVU (Experimental Example 2-4).

[0059] The viscosity characteristics of the rice flour gelatin solution were measured using a Rapid Visco Analyzer (RVA), and the peak viscosity, final viscosity, trough viscosity, breakdown viscosity, and setback values ​​were obtained. The viscosity unit was expressed as Rapid Visco Unit (RVA).

[0060] The rice flour obtained through step (5) of the present invention has a characteristic in which the loss modulus (G″) is higher than the storage modulus (G′) when hydrated in water (Experimental Example 2-5).

[0061] Viscoelasticity is a phenomenon in which, when force is applied to an object, it exhibits properties of both solid and liquid, and it simultaneously exhibits elasticity and viscosity, which are properties that try to return to their original state.

[0062] The storage modulus (G′) is the component in which deformation energy is stored as stress inside the material, and quantifies the elastic component of the material, that is, the behavior of a solid. The loss modulus (G″) is the component in which the energy given to the material is converted into other energy such as heat and lost, and quantifies the viscous component of the material, that is, the behavior of a liquid. Materials that behave like flowing liquids have the characteristic of having a loss modulus (G″) that is much higher than the storage modulus (G′).

[0063] It was confirmed that the rice flour obtained through step (5) of the present invention had a reduced surface roughness of the rice flour when hydrated in water, and specifically, as the ultrasonic treatment time increased, the network structure of the starch chains of the rice flour was destroyed, so that the viscosity of the suspension of the gelatinized rice flour was reduced, and the dispersibility recovery rate was increased when rehydrated in an aqueous solution, so that rice flour with improved dispersion stability was manufactured (Experimental Example 2-6).

[0064] Another aspect provides rice flour with improved dispersion stability and low sedimentation rate obtained by the rice flour manufacturing method of the present invention, and a rice beverage composition including the rice flour.

[0065] The term "rice drink" of the present invention refers to a food product in the form of a beverage containing rice, which may include a liquid, solid, or an intermediate form between a liquid and a solid. Specifically, the rice drink may be a beverage, a frozen dessert, a shake, or a snack, and more specifically, as a beverage, it may be a tea drink, an energy drink, a carbonated drink, a drink, an alcoholic beverage, a vitamin complex, etc., and as a frozen dessert, it may be a smoothie, a slush, an ice cream, etc., but is not limited thereto.

[0066] The term "rice beverage composition" of the present invention means a material that can be used in the production of the rice beverage, and the amount of the rice beverage composition included in the rice beverage is not particularly limited and can be easily determined by a person skilled in the art depending on the purpose.

[0067] In this specification, the rice beverage composition may be used interchangeably with the term ‘rice beverage base’.

[0068] Another aspect provides a food comprising the above rice beverage composition.

[0069] Another aspect provides a rice beverage comprising the above rice flour or the above rice beverage composition.

[0070] The food composition of the present invention can be manufactured using methods commonly used in the art, and can be manufactured by adding raw materials and ingredients commonly added in the art. Furthermore, the food composition can be manufactured in a variety of formulations without limitation, as long as it is a formulation recognized as a food.

[0071] In addition, the food composition may additionally include a physiologically acceptable carrier, and the type of the carrier is not particularly limited, and any carrier commonly used in the relevant technical field may be used.

[0072] In addition, the food composition may include additional ingredients commonly used in food compositions to improve odor, taste, sight, etc. For example, it may include vitamins A, C, D, E, B1, B2, B6, B12, niacin, biotin, folate, pantothenic acid, etc. In addition, it may include minerals such as zinc (Zn), iron (Fe), calcium (Ca), chromium (Cr), magnesium (Mg), manganese (Mn), copper (Cu), chromium (Cr), etc.; and amino acids such as lysine, tryptophan, cysteine, etc.

[0073] In addition, the food composition may include food additives such as preservatives (potassium sorbate, sodium benzoate, salicylic acid, sodium dehydroacetate, etc.), sterilizers (bleaching powder and high-purity bleaching powder, sodium hypochlorite, etc.), antioxidants (butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT), etc.), colorants (tar colorants, etc.), colorants (sodium nitrite, sodium nitrite, etc.), bleaching agents (sodium sulfite), seasonings (MSG, monosodium glutamate, etc.), sweeteners (dulcin, cyclamate, saccharin, sodium, etc.), flavorings (vanillin, lactones, etc.), leavening agents (alum, D-potassium hydrogen tartrate, etc.), reinforcing agents, emulsifiers, thickeners (glucose fillers), film-forming agents, gum-forming agents, foam suppressants, solvents, and improvers. The above additives can be selected according to the type of food and used in an appropriate amount.

[0074] According to specific embodiments and experimental examples of the present invention, the inventors of the present invention manufactured ultrasonically treated rice powder having improved dispersion stability through ultrasonic treatment (3 minutes (3T), 6 minutes (6T), 9 minutes (9T), 12 minutes (12T), or 15 minutes (15T)) and thus suitable for use as a beverage material (Example 1). In addition, as a comparative example, dry-ground rice powder was sieved through a sieve (150 μm, 125 μm, 100 μm, 75 μm, and 50 μm sieve) to prepare selected rice powder (Comparative Example 1). In addition, using the selected rice powder of Comparative Example 1, a rice powder gelatinization solution and gelatinized rice powder were manufactured under the same conditions and methods as in Example 1, but gelatinized rice powder (0T) was prepared without ultrasonic treatment (Comparative Example 2). The flow characteristics of the untreated ultrasonic wave were confirmed in an aqueous solution. In Comparative Example 1, which is an untreated ultrasonic wave, insoluble rice was confirmed to have formed sediment in the rice flour aqueous solution mixed with water, and the dispersibility was not excellent (Comparative Example 1 and Fig. 1). In addition, it was confirmed that the untreated ultrasonic wave gelatinized rice flour aqueous solution formed a high viscosity gel and could not be used as an ingredient in a beverage (Comparative Example 1 and Fig. 1). The particle size distribution of the selected rice flour of Comparative Example 1 was plotted as a curve, and the median D50 of the rice flour particle size was 31.69 μm, the maximum D99 of the rice flour particle size was 221.24 μm, and 63.65% of the total rice flour had a particle size exceeding 50 μm (Fig. 2). In addition, the inventors confirmed the dispersion stability of the rice flour suspension of Comparative Example 1 that was not ultrasonically treated, and confirmed that sedimentation occurred in the rice flour suspension after 1 day regardless of the rice flour particle size (Fig. 3a). In addition, as the storage time of the rice flour suspension increased, the normalized absorption (abs) decreased regardless of the rice flour particle size, indicating that the rice flour sedimented and the solution became transparent (Fig. 3b).In addition, the hydration characteristics of the non-ultrasonicated rice flour of Comparative Example 1 showed no significant difference in water absorption index (WAI) and swelling power (SP), but starch solubility (WS) tended to increase as the rice flour particle size decreased, but did not show a significant difference (Table 1). Except for the rice flour (U) with a particle size of less than 50 ㎛, the non-ultrasonicated rice flour of Comparative Example 1 showed a higher yellowness (b) than the whole rice flour (F), and the color difference value (ΔE) could be distinguished with the naked eye compared to the whole rice flour (F) (Table 1). In addition, the inventors measured the viscosity of the rice flour gelatinization solution according to the particle size of the rice flour of Comparative Example 2, and as a result, the peak viscosity and final viscosity tended to increase significantly as the particle size of the rice flour decreased (Table 2 and Fig. 4). The complex viscosity according to particle size was the highest for rice flour (U) less than 50㎛, followed by the entire rice flour sample (F), and the complex viscosity values ​​of the remaining medium-sized rice flours did not show a significant difference (Fig. 5). As described above, the inventors of the present invention confirmed that Comparative Examples 1 and 2, which were not ultrasonicated, were not suitable for use as materials for making beverages because sediment was generated, dispersion stability was not excellent, and the gelatinized rice flour had high viscosity. The inventors analyzed the flow characteristics of the ultrasonicated rice flour of Example 1, and found that the unsonicated group (Comparative Example 2) formed a hard gel and the rice flour gelatin solution did not flow out when the container was turned over, but the ultrasonicated group (Example 1) had a flow-out characteristic, which was confirmed with the naked eye that the ultrasonic treatment gave it the characteristics of a liquid (Fig. 6). In addition, when the inventors of the present invention rehydrated the ultrasonically treated gelatinized rice flour of Example 1, the turbidity did not change even when the rice flour suspension was left for 12 hours (Fig. 7a).In addition, it was confirmed that the dispersion stability of the gelatinized rice flour suspension was continuously maintained because there was no change in the normalized absorption (abs) even when left as is for 12 hours after the sonication regardless of the sonication time (Fig. 7b). The inventors of the present invention measured the water retention capacity (WAI), swelling power (SP), and starch solubility (WS%) of the sonicated rice flour to confirm the hydration characteristics. The water retention capacity (WAI) and swelling power (SP) of the sonicated group were lower than those of the unsonicated gelatinized rice flour (0T, Comparative Example 2), but the starch solubility (WS%) of the sonicated group was confirmed to be significantly increased compared to the unsonicated group, proving that the solubility increased due to the sonication (Table 3). In addition, the ultrasonic treatment group was measured to have a much lower viscosity than the general rice flour (F) and the ultrasonic non-treated gelatinized rice flour (0T) (Table 4 and Fig. 8a and), and it was confirmed that the final viscosity showed a very low value, especially when ultrasonic treatment was performed for 12 minutes and 15 minutes (Table 4 and Fig. 8b). In addition, the inventors of the present invention found that the loss modulus (G″, green line), which is a viscous (liquid) characteristic, was higher than the storage modulus (G′, blue line), which is an elastic (solid) characteristic, in the diagram showing the storage modulus (G′, blue line) and the loss modulus (G″, green line) of the ultrasonic-treated rice flour, thereby confirming that the ultrasonic-treated rice flour had liquid properties (Fig. 9a), and the complex viscosity (η*, Pa·s) of the ultrasonic-treated rice flour decreased with the ultrasonic treatment time (Fig. 9b), confirming that the ultrasonic-treated gelatinized rice flour suspension showed liquid properties and was therefore suitable for use as a beverage material.Finally, the structure of the gelatinized rice flour powder was confirmed using scanning electron microscopy (SEM) images of the unsonicated (a) and the sonicated (3 min (b), 6 min (c), 9 min (d), 12 min (d), and 15 min (f) sonicated. It was structurally confirmed that the surface roughness of the rice flour disappeared as the sonication time increased. Compared to the unsonicated (unsonicated) sample, it can be predicted that the viscosity of the gelatinized rice flour suspension decreased and the dispersion stability improved due to this structural difference.

[0075] Hereinafter, the present invention will be described in detail through examples and experimental examples.

[0076] However, the following examples and experimental examples are only illustrative of the present invention, and the content of the present invention is not limited by the following examples and experimental examples.

[0077] <Example 1> Preparation of ultrasonic-treated rice flour

[0078] Through trial and error, the inventors of the present invention have produced rice flour with improved dispersion stability, making it suitable for use as an ingredient in foods such as rice beverages. Specifically, rice was ground, mixed with water and rice flour in a ratio of about 9:1 to produce a rice flour slurry containing about 10 wt% of the mixture, and then a gelatinized solution was produced by stirring at 90°C for more than 1 hour. The resulting gelatinized solution was cooled to about 25°C, then ultrasonicated for 3 minutes (3T), 6 minutes (6T), 9 minutes (9T), 12 minutes (12T), or 15 minutes (15T), followed by homogenization, cooling to about -20°C, and freeze-drying to obtain the desired rice flour.

[0079] <Comparative Example 1> Preparation of ground rice flour without ultrasonic treatment

[0080] We obtained dry-ground rice flour (2022) using an air-flow grinder commonly used in flour mills, and prepared whole rice flour (F) with a wide particle size distribution without sieving, and rice flour with particle size selected using sieves of 150 ㎛, 125 ㎛, 100 ㎛, 75 ㎛, and 50 ㎛.

[0081] <Comparative Example 2> Preparation of non-ultrasonic-treated gelatinized rice flour

[0082] Using the selected rice flour of Comparative Example 1, a rice flour gelatin solution was made under the same conditions and method as Example 1, and gelatinized rice flour was prepared therefrom, but gelatinized rice flour (0T) was obtained without ultrasonic treatment.

[0083] <Experimental Example 1> Analysis of Physical Properties of Untreated Rice Flour

[0084] <Experimental Example 1-1> Flow characteristics of rice flour aqueous solution

[0085] The inventors of the present invention confirmed the flow characteristics of the solution when 0.5 wt% of the general rice flour of Comparative Example 1 was mixed with 100 wt% of water and stored at room temperature for 1 day, 10 wt% of the general rice flour of Comparative Example 1 was mixed with 100 wt% of water and stored at room temperature for 1 day, 10 wt% of the gelatinized rice flour of Comparative Example 2 was mixed with 10 wt% of water and stored at room temperature for 1 day, and 10 wt% of the gelatinized rice flour of Comparative Example 2 was mixed with 10 wt% of water and heat-treated, and then stored at 4°C for 1 day.

[0086] As a result, when mixed and stored with 0.5 wt% of the general rice flour of Comparative Example 1, the aqueous solution was more transparent than when mixed with 10 wt% of the general rice flour, but when mixed with water with 0.5 wt% and 10 wt% of the general rice flour and stored, it was confirmed that insoluble rice precipitated (Fig. 1). When the gelatinized rice flour of Comparative Example 1 was mixed with water at 10 wt% and stored at room temperature for 1 day, it was separated into a gel layer and a water layer, and when the gelatinized rice flour of Comparative Example 1 was mixed at 10 wt% and then heat-treated and stored at 4°C for 1 day, a high-viscosity gel was formed and hardened, and it was confirmed that it did not flow out even when the container was turned over (Fig. 1).

[0087] Accordingly, regular rice flour, which is inherently insoluble, sank when mixed with water and stored, resulting in poor dispersibility of rice flour aqueous solutions. Furthermore, it was confirmed that gelatinized rice flour formed a high-viscosity gel, limiting its use as a beverage ingredient.

[0088] <Experimental Example 1-2> Analysis of particle size distribution of rice flour

[0089] The rice flour selected using the sieve of Comparative Example 1 was measured for particle size using a particle size analyzer and the particle size distribution was analyzed. The particle size distribution curve, which represents the relative cumulative distribution and density distribution curves for each particle size of the entire rice flour powder, was diagrammed. Specifically, the values ​​corresponding to 10%, 50%, 90%, and 99% of the largest particle size in the cumulative distribution were represented as D10, D50, D90, and D99, respectively, and the distribution curve was diagrammed using the measured values.

[0090] The particle size of rice flour was 5.44㎛ for D10, 31.69㎛ for D50, 136.58㎛ for D90, and 221.24㎛ for D99, the maximum particle size of rice flour (Fig. 2). In addition, among the total particles of rice flour, 7.46% had a particle size exceeding 150㎛, 19.12% had a particle size exceeding 100㎛, and 63.65% had a particle size exceeding 50㎛ (Fig. 2).

[0091] <Experimental Example 1-3> Analysis of dispersion stability according to particle size of rice flour

[0092] The inventor of the present invention analyzed the dispersion stability of a rice flour suspension according to the particle size of the rice flour by mixing the rice flour of Comparative Example 1 with water. Specifically, whole rice flour (F) which is dry-ground and not sieved and thus has a variety of particle sizes, rice flour whose particle size was selected using sieves of 150 ㎛, 125 ㎛, 100 ㎛, 75 ㎛, and 50 ㎛, and rice flour (U) having a particle size of less than 50 ㎛ were mixed in water at 10 wt% each, and the sedimentation of the rice flour suspension stored for 1 day was visually confirmed and the normalized absorption (abs) value was plotted.

[0093] As a result, regardless of particle size, it was confirmed that sedimentation occurred after 1 day in rice flour suspensions with particle sizes exceeding 150㎛, exceeding 100㎛, and less than 50㎛ (U) (Fig. 3a). Normalized absorption (abs) means that the solution becomes more transparent as the value decreases. Regardless of the particle size of the rice flour, the absorbance decreased as the storage time after making the rice flour suspension increased, and it was confirmed that sedimentation was complete in all groups after 7 hours (420 minutes) to 8 hours (560 minutes). However, it was confirmed that the sedimentation occurred the slowest in the whole rice flour (F) that was not sieved with a wide particle size distribution and in the rice flour with a particle size of less than 50㎛ (U) (Fig. 3b).

[0094] In summary, it was confirmed that the untreated general rice flour suspension was not suitable for use as a beverage material because the rice flour settled and formed sediment regardless of the size of the rice flour particles during storage.

[0095] <Experimental Example 1-4> Analysis of hydration and color characteristics according to particle size of rice flour

[0096] The inventors of the present invention analyzed the hydration and color characteristics according to particle size of the whole rice flour (F) of Comparative Example 1, rice flour selected by particle size using sieves of 150㎛, 125㎛, 100㎛, 75㎛ and 50㎛, and rice flour (U) having a particle size of less than 50㎛. Specifically, the hydration characteristics of the rice flour were measured by centrifuging 25 mL of a 2% (w / v) rice flour solution at a speed of 3000×g using the AACC Method, and measuring the water absorption index (WAI), swelling power (SP) and water solubility (WS%) from the sediment and supernatant residue. The water absorption index represents the water retention capacity. The color characteristics were measured by pressing the powder into a petri dish with a diameter of 30 mm, sealing it, and using a colorimeter (Ultrascan pro, Hunterlab, VA, USA) to measure the lightness (L), redness (a), yellowness (b), and color difference value (ΔE).

[0097] The water absorption index (WAI) and swelling power (SP) of rice flour did not show significant differences according to particle size. Starch solubility (WS) tended to increase with decreasing rice flour particle size, but the increase was only about 1-2%, showing no significant difference (Table 1).

[0098] In terms of color characteristics, the yellowness (b) value of rice flour with particle sizes less than 50㎛ (U) was higher than the yellowness (b) of 4.85 of the whole rice flour (F), and the color difference value (ΔE) was in the range of 2.06 to 4.32 compared to the whole rice flour (F), which was a level that could be distinguished with the naked eye (Table 1).

[0099] Particle size, water absorption index (WAI), swelling power (SP), starch solubility (WS%), lightness (L), redness (a), yellowness (b), color difference value (ΔE), total rice flour (F) 2.65 ± 0.06 9.25 ± 1.0 18.59 ± 1.56 a 94.47±0.02 b -0.24±0.01 e 4.85±0.01 f ->150㎛2.58±0.088.57±0.186.15±0.82 c 92.67±0.01 d -0.29±0.02 f 6.86±0.02 d 2.70±0.01 d >125㎛2.60±0.108.93±0.087.03±0.12 bc 91.83±0.02 g 0.02±0.01 a 8.26±0.04 a 4.32±0.05 a >100㎛2.66±0.088.94±0.187.03±0.19 bc 92.37±0.01 e -0.02±0.00 b 7.87±0.01 b 3.69±0.01 b >75㎛2.56±0.059.00±0.137.15±0.09 bc 92.23±0.02 f -0.13±0.01 c 7.45±0.02 c 3.44±0.02 c >50㎛2.73±0.139.30±0.087.81±0.10 ab 93.40±0.01 c -0.02±0.00 b6.59±0.01 e 2.06±0.01 e <50㎛2.73±0.059.10±0.277.50±0.91 abc 94.52±0.01 a -0.16±0.01 d 3.98±0.01 g 0.87±0.01 f

[0100] <Experimental Example 1-5> Analysis of gelatinization and viscosity characteristics of rice flour gelatin solution according to rice flour particle size

[0101] The viscosity of the rice flour gelatinization solution of Comparative Example 2 was measured using a Rapid Visco Analyzer (RVA). The viscosity of the gelatinization solution of whole rice flour (F), rice flour selected by particle size using sieves of 150㎛, 125㎛, 100㎛, 75㎛, and 50㎛, and rice flour with a particle size of less than 50㎛ (U) was measured. The viscosity was investigated in terms of peak viscosity, trough viscosity, final viscosity, breakdown viscosity, and setback viscosity. Breakdown viscosity represents the difference between the trough viscosity and the peak viscosity, and setback viscosity represents the difference between the final viscosity and the peak viscosity.

[0102] As a result of investigating the difference in gelatinization characteristics according to particle size, it was shown that the smaller the particle size of rice flour, the more significantly the peak viscosity and final viscosity increased (Table 2 and Fig. 4).

[0103] As a result of measuring the complex viscosity according to particle size, the rice flour (U) with a particle size of less than 50㎛ that passed the 50㎛ sieve showed the highest viscosity, followed by the entire rice flour sample (F), and the complex viscosity values ​​of the remaining medium-sized rice flours did not show a significant difference (Fig. 5).

[0104] In summary, we confirmed that the smaller the particle size of rice flour, the higher the viscosity during gelatinization. Therefore, we confirmed that rice flour with smaller particles actually exhibits increased viscosity during gelatinization, making it unsuitable for use as a beverage ingredient.

[0105] Particle size Peak viscosity (RVU) Drop viscosity (RVU) Final viscosity (RVU) Set point viscosity (RVU) Whole rice flour (F) 127.39±1.38 e 59.78±0.97d e 142.19±0.70 e 14.81±0.83 ab >150㎛132.58±2.05 e 53.17±1.00 e 153.00±1.67 d 20.41±0.63 a >125㎛148.50±1.21 d 63.72±1.08 cd 162.92±1.09 c 14.42±0.42 ab >100㎛159.94±5.34 c 69.33±2.39 c 172.56±4.20 b 12.61±1.29 bc >75㎛166.83±12.39 c 80.28±10.84 b 172.20±9.76 b 5.36±7.73 bc >50㎛179.08±0.88 b 82.22±2.22 b 187.86±1.07 a 8.78±0.19 c <50㎛189.89±5.35 a 101.89±4.04 a 183.89±1.04 a -6.00±4.51 d

[0106] <Experimental Example 2> Analysis of physical properties of ultrasonic-treated rice flour

[0107] <Experimental Example 2-1> Analysis of the flow characteristics of ultrasonically treated rice flour aqueous solution

[0108] The inventor of the present invention confirmed the flow characteristics of the ultrasonic-treated rice flour gelatin solution of Example 1 and the ultrasonic-untreated gelatin solution (Comparative Example 2).

[0109] As a result, based on the storage standard at 4℃, the unultrasonic treated group (Comparative Example 2) maintained a solid gel form and the rice flour gelatin solution, which had a solid nature, did not flow out even when the container was turned over, whereas the ultrasonic treated group (Example 1) had a characteristic of flowing out immediately when the container was turned over, confirming that the rice flour gelatin solution changed into a liquid state due to ultrasonic treatment (Fig. 6).

[0110] <Experimental Example 2-2> Analysis of the dispersion stability of rice flour according to ultrasonic treatment time

[0111] The inventors of the present invention investigated the dispersion stability of a suspension of gelatinized rice flour by rehydrating the powdered gelatinized rice flour of Example 1 with 10 wt% of the water weight. Specifically, the dispersion stability of regular rice flour (F, Comparative Example 1) and the ultrasonic-treated groups (3T, 6T, 9T, 12T, 15T) of Example 1 was investigated.

[0112] When all ultrasonic treatment groups were left at room temperature for 7 days, all ultrasonic treatment groups maintained a dispersed state, whereas sedimentation occurred in the regular rice flour (F, Comparative Example 1), which was visually confirmed (Fig. 7a). In addition, compared to regular rice flour (F, Comparative Example 1) and gelatinized rice flour (0T, Comparative Example 2), all ultrasonic treatment groups treated with 3T, 6T, 9T, 12T, and 15T did not show any change in turbidity until the rice flour suspension was left as is for 7 days (Fig. 7a). In addition, when the normalized absorption (abs) of the gelatinized rice flour suspension was checked, all ultrasonic treatment groups showed no change in absorbance even after 12 hours (720 minutes) of storage, confirming that the dispersion stability was continuously maintained (Fig. 7b). On the other hand, the absorbance of general rice flour (F, Comparative Example 1) tended to decrease as the storage time increased, and the absorbance decreased rapidly from 7 hours (420 minutes) and maintained a very low absorbance after 9 hours (540 minutes), confirming that the rice flour had settled and the absorbance of the aqueous solution had decreased, and that the dispersion stability had decreased (Fig. 7b).

[0113] In summary, the ultrasonic treatment group showed the characteristics of gelatinized rice flour that maintained dispersion stability regardless of the treatment time of 3 to 15 minutes, making it suitable for use as a beverage material.

[0114] <Experimental Example 2-3> Analysis of hydration characteristics of rice flour according to ultrasonic treatment time

[0115] The inventors of the present invention analyzed the hydration characteristics of general rice flour (F, Comparative Example 1), ultrasonically untreated gelatinized rice flour (0T, Comparative Example 2), and ultrasonically treated groups (3T, 6T, 9T, 12T, 15T) of Example 1, and specifically confirmed the water retention capacity (WAI), swelling power (SP), and starch solubility (WS%).

[0116] The ultrasonic treatment group showed lower water retention capacity (WAI) and swelling power (SP) than the untreated ultrasonic gelatinized rice flour (0T, Comparative Example 2), but the starch solubility (WS%) was confirmed to increase rapidly from 13.06 WS% in the untreated group to 70.84 to 85.70 WS% in the ultrasonic treatment group (Table 3). The regular rice flour (F, Comparative Example 1) showed lower water retention capacity than the ultrasonic treatment group of Example 1, but its swelling power (SP) tended to be higher. In addition, the starch solubility (WS%) was confirmed to be very high in the ultrasonic treatment group, at 70.84 to 85.70 WS%, while the regular rice flour (F, Comparative Example 1) showed a very low value of 8.59 WS%, at 8.59 WS% in the ultrasonic treatment group (Table 3).

[0117] In summary, the ultrasonic treatment Example 1 of the present invention showed high starch solubility for all ultrasonic treatment times (3T, 6T, 9T, 12T, 15T), confirming that the solubility increased due to better penetration of water particles through structural changes in the gelatinized rice flour gelatinized by ultrasonic treatment.

[0118] Ultrasonic treatment time Water retention capacity (WAI) Swelling power (SP) Water solubility (WS%) Regular rice flour (F) 2.73±0.05e9.25±1.01b8.59±1.56f Unultrasonic treatment Luxury rice flour (0T) 10.47±0.46a 13.08±0.06a 13.06±0.31e 3T 6.76±0.71b 3.94±0.12d 70.84±0.72d 6T 4.88±0.12c 2.53±0.03c 77.37±0.20c 9T 3.59±0.44d 1.53±0.04e 82.80±0.41b 12T 2.65±0.41e 1.12±0.04e 85.95±0.04a 15T 3.06±0.17de 1.16±0.09e 85.70±0.63a

[0119] *F: regular rice flour, 0T: non-ultrasonic gelatinized rice flour, 3T, 6T, 9T, 12T, 15T: ultrasonic gelatinized rice flour (3, 6, 9, 12, 15 minutes)

[0120] <Experimental Example 2-4> Analysis of the gelatinization characteristics of rice flour according to ultrasonic treatment time

[0121] The inventors of the present invention analyzed the gelatinization characteristics of general rice flour (F, Comparative Example 1), ultrasonically untreated gelatinized rice flour (0T, Comparative Example 2), and ultrasonically treated rice flours of Example 1 (3T, 6T, 9T, 12T, 15T).

[0122] As a result, it was confirmed that the ultrasonic treatment groups (3T, 6T, 9T, 12T, 15T) had very low viscosity compared to regular rice flour (F) and untreated ultrasonic gelatinized rice flour (0T) (Table 4 and Fig. 8a and). After 9 minutes (9T) of ultrasonic treatment, the peak viscosity was 7.14±0.13 to 8.06±0.17 RVU, showing no significant difference, and the final viscosity was 4.59±0.14 and 4.42±0.25 RVU after 12 minutes (12T) of treatment, i.e., 12 minutes and 15 minutes of treatment, respectively, showing no significant difference, indicating that the viscosity was measured as a very low value (Table 4 and Fig. 8b).

[0123] Ultrasonic treatment time Peak viscosity (RVU) Viscosity drop (RVU) Final viscosity (RVU) Setting viscosity (RVU) Regular rice flour (F) 144.33±7.37 b 69.45±4.11 b 154.66±5.78 a 10.33±1.72 a Ultrasonic untreated glutinous rice flour (0T) 223.19±3.92 a 147.89±2.14 a 154.94±5.29 a -68.25±2.73 d 3T20.22±1.55 c 13.28±1.30 c 13.28±0.39 b -6.95±1.18 c 6T11.89±0.13 d 7.56±0.17 d 7.56±0.17 c -4.33±0.22 b9T7.95±0.25 d 5.11±0.19 d 5.39±0.53 c -2.56±0.77 b 12T8.06±0.17 d 5.69±0.13 d 4.59±0.14 c -3.39±0.17 b 15T7.14±0.13 d 4.97±0.13 d 4.42±0.25 c -2.80±0.21 b

[0124] *F: regular rice flour, 0T: non-ultrasonic gelatinized rice flour, 3T, 6T, 9T, 12T, 15T: ultrasonic gelatinized rice flour (3, 6, 9, 12, 15 minutes)

[0125] According to the above results, it was confirmed that the suspension of rice flour gelatinized by ultrasonic treatment exhibited the characteristic of very low viscosity.

[0126] <Experimental Example 2-5> Analysis of Viscoelastic Properties of Rice Flour According to Ultrasonic Treatment Time

[0127] The inventors of the present invention analyzed the viscoelastic properties of rice flour according to the ultrasonic treatment time of Example 1, and specifically confirmed the storage modulus ((G′, Pa) blue line), loss modulus ((G″, Pa) green line), and viscosity (η*, Pa·s). The ultrasonic treatment group of the present invention was compared with the results of the general rice flour (F) of Comparative Example 1. In the diagram showing the loss modulus-storage modulus, if the loss modulus is located above the storage modulus, it exhibits the characteristics of a liquid, and if the storage modulus is located above the loss modulus, it exhibits the characteristics of a solid.

[0128] As a result, the storage modulus (G′, blue line) and loss modulus (G″, green line) tended to decrease with the ultrasonic treatment time, and did not show a significant difference when treated for more than 9 minutes (Fig. 9a). When the storage modulus and loss modulus were compared, the loss modulus (G″, green line) was higher than the storage modulus (G′, blue line) in all ultrasonic treatment groups, which means that the ultrasonic-treated rice flour gel has more viscous characteristics than elasticity, so it has properties closer to a liquid (Fig. 9a).

[0129] On the other hand, the general rice flour (F) of Comparative Example 1, which was not ultrasonic treated, showed a storage modulus (G′, blue line) higher than the loss modulus (G″, green line), indicating that elasticity was higher than viscosity, confirming that the rice flour exhibited solid properties (Fig. 9a). The complex viscosity (η*, Pa·s) tended to decrease with the ultrasonic treatment time, and when treated for 9 minutes or longer, there was no significant difference from the 12-minute and 15-minute ultrasonic treatment groups (Fig. 9b).

[0130] In summary, the relationship between the storage modulus and the loss modulus and the complex viscosity were analyzed, and it was experimentally confirmed that the suspension of ultrasonically treated gelatinized rice flour has liquid properties when hydrated in water. It was also confirmed that ultrasonically treated gelatinized rice flour powder can be usefully used as a beverage material.

[0131] <Experimental Example 2-6> Structural Analysis of Rice Flour Using SEM Photography

[0132] The inventors analyzed the structure of the gelatinized rice flour powder treated with ultrasound for 3 minutes (b), 6 minutes (c), 9 minutes (d), 12 minutes (d), and 15 minutes (f) using scanning electron microscope (SEM) images.

[0133] As a result, it was confirmed that the surface roughness of the ultrasonic-treated gelatinized rice flour powder gradually disappeared as the ultrasonic treatment time increased from 3 minutes (b), 6 minutes (c), 9 minutes (d), 12 minutes (d), and 15 minutes (f) compared to the untreated group (a) (Fig. 10). Before ultrasonic treatment, the network structure by the starch chains was maintained, but it was confirmed that the network structure was destroyed by ultrasonic treatment, reducing the surface roughness of the rice flour powder. It is presumed that the change in structure reduced the viscosity of the gelatinized rice flour suspension and improved the dispersion stability in an aqueous solution.

Claims

1. (1) A step of preparing a slurry by mixing rice flour into water; (2) A step of producing a rice flour gelatin solution by stirring the produced slurry while applying heat; (3) Step of cooling the manufactured rice flour gelatin solution; (4) Step of ultrasonic treatment of the cooled rice flour gelatin solution; and (5) A method for producing rice flour with improved dispersion stability, comprising the step of homogenizing and drying a rice flour gelatin solution treated with ultrasound.

2. In paragraph 1, A manufacturing method in which, in the above step (1), the mixing ratio of water and rice flour is 3:1 to 19:1 based on weight.

3. In paragraph 1, A manufacturing method wherein in the above step (2), the rice flour gelatinization solution is a completely gelatinized rice flour gelatinization solution.

4. In paragraph 1, A manufacturing method comprising cooling to a temperature of 10 to 35°C in the above step (3).

5. In paragraph 1, A manufacturing method, wherein ultrasonic treatment is performed for 1 to 60 minutes in the above step (4).

6. In paragraph 1, A manufacturing method in which rice flour obtained through the above step (5) does not undergo sedimentation or change in turbidity with an increase in storage period after being hydrated in water.

7. In paragraph 1, A manufacturing method wherein the rice flour obtained through the above step (5) exhibits increased starch solubility (water solubility, WS%) when measuring the starch solubility of a rice flour solution made by hydrating it in water compared to unultrasonicated rice flour.

8. In paragraph 1, A manufacturing method wherein rice flour obtained through the above step (5) exhibits reduced viscosity when measured for viscosity by hydrating it in water compared to rice flour not treated with ultrasonic waves.

9. In paragraph 1, A manufacturing method wherein rice flour obtained through the above step (5) exhibits a higher loss modulus (G″) than the storage modulus (G′) when hydrated in water.

10. In paragraph 1, A manufacturing method in which the surface roughness of the rice flour obtained through the above step (5) is reduced when the rice flour is hydrated in water.

11. Rice flour with improved dispersion stability and low sedimentation rate manufactured by the manufacturing method of Article 1.

12. A food composition comprising rice flour of Article 11.

13. Food containing the composition of Article 12.

14. A rice beverage comprising the rice flour of clause 11 or the composition of clause 12.

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