Frozen noodles designed for pre-thawing.

Abstract

To adjust the texture of frozen udon noodles to an optimal level even after two or more hours after thawed, and to boil boiled noodles while restraining surfaces of weakened boiled noodles from becoming rough by adding starch.SOLUTION: Provided is method of manufacturing udon noodles, including a kneading step of adding kneading water to a powdery raw material comprising wheat flour as a main material and containing either or both of etherified starch and acetylated starch and kneading to form noodle dough, a noodle-making step of forming the dough into noodle strips, and rolling and shredding the strips to make raw noodles, a boiling step of boiling the raw noodles at a temperature of 110°C to 130°C under pressure and cooling to make boiled noodles, a freezing step of freezing the boiled noodles, and a standing step of thawing the frozen noodles and then allowing them to stand for two hours or more at a temperature of 5 to 25°C.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to frozen udon that is pre-thawed and waiting for consumption in bento boxes, side dishes, banquets, catering, etc., and is suitable for eating after a lapse of time, a method for improving the texture of frozen udon, and a method for manufacturing udon. The above method for manufacturing udon relates to a technique in which aging-resistant starch is blended with wheat flour as the main raw material and boiled at a high temperature exceeding 100°C in a pressurized environment.

Background Art

[0002] It is known that boiling at a temperature exceeding 100°C in a pressure cooker increases the degree of gelatinization and improves the texture of the noodles. However, due to the unintentional decompression of the headspace, the noodles themselves may boil along with the boiling water, causing significant roughening of the surface. In addition, when boiling at a high temperature exceeding 100°C, the highly gelatinized and weakened noodle structure is likely to cause roughening of the surface due to physical impacts such as being kneaded by the water flow.

[0003] According to Patent Document 1, a technique has been proposed to improve roughening and disintegration by degassing and kneading noodle dough in a decompressed environment. In addition, according to Patent Document 2, a technique has been proposed to provide noodles with an elastic texture and less roughening and disintegration associated with a shortened boiling time by limiting the moisture content of the noodles during boiling to 55 to 68% by weight.

[0004] In Patent Document 3, in order to maintain the pressurized state of the pressurized boiling chamber, a pre-chamber is provided on the input side and a post-chamber is provided on the discharge side. Foods such as noodles are put into the pressurized boiling chamber and transferred with a reversing basket while潜行 in the boiling water, and a boiling processing apparatus has been proposed that can compensate for the pressure drop in the pressurized boiling chamber by the provided pressurizing means.

[0005] Furthermore, Patent Document 4 proposes a method for manufacturing boiled noodles, comprising: (1) a low-temperature boiling step of boiling raw noodle strands at 70°C or higher under atmospheric pressure; (2) a high-temperature boiling step of boiling the boiled noodle strands in parallel in units of one serving or less under a pressurized environment exceeding 100°C; and (3) a cooling step of moving the boiled unit noodle strands in parallel from a temperature exceeding 100°C to 70°C or lower, and then submerging the entire unit noodle strand in a cooling water tank to cool it down. The high-temperature boiling step (2) and the cooling step (3) are performed simultaneously under a common pressurized environment by moving the noodles through a high-temperature water tank and a cooling water tank, respectively, using a common circulating basket, and the noodles are added and removed using an input pipe and an output pipe equipped with internal and external pipe valves. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 60-176554 [Patent Document 2] Japanese Patent Publication No. 3-195466 [Patent Document 3] Japanese Patent Publication No. 2008-302119 [Patent Document 4] Japanese Patent Publication No. 2017-130 [Overview of the project] [Problems that the invention aims to solve]

[0007] In the commercial noodle market, there is a need for specialized frozen noodles suitable for consumption after a period of time following thawing, to meet the demands of various eating occasions such as bento boxes, prepared meals, banquets, and catering. Such products have already been commercialized. However, conventional methods of using raw materials and noodle-making techniques, which are based on boiling under atmospheric pressure, have been insufficient to compensate for the deterioration of noodle texture due to several hours of sogginess.

[0008] Even rapidly frozen boiled udon noodles will lose their texture if left for several hours after thawing due to the equalization of moisture and the so-called retrogradation of starch. To mitigate this deterioration in texture, retrogradation-resistant starch is generally added. However, excessively increasing the starch ratio can lead to problems such as the noodles not separating easily when broth is poured over them, and the relative decrease in the wheat flour ratio can impair the wheat-derived flavor of the noodles.

[0009] Furthermore, udon noodles boiled at temperatures exceeding 100°C under pressure are inherently fragile and prone to causing skin irritation, but the addition of etherified starch and acetylated starch further weakens them, making them even more susceptible to skin irritation.

[0010] In other words, the problem that this invention aims to solve is to optimize the texture of noodles such as udon after several hours have passed since thawing, while keeping the starch content within an appropriate range by boiling them at a temperature exceeding 100°C under a pressurized environment, and furthermore, to boil the noodles while suppressing the roughness of the surface that has been weakened by the starch content. [Means for solving the problem]

[0011] In order to solve these problems, the inventors explored various methods and discovered that when frozen udon noodles, which were boiled at 120°C under pressure and blended with retrogradation-resistant starch, were thawed and consumed after two hours, they retained an excellent texture that was not observed when boiled under atmospheric pressure, thus completing the present invention.

[0012] In other words, the present invention is defined by the following inventive features. (1) A method for producing udon noodles, characterized by comprising, in order: (1) a kneading step in which water is added to a powder raw material that mainly consists of wheat flour and contains either or both etherified starch and acetylated starch, and kneaded to make noodle dough; a noodle-making step in which the noodle dough is formed into a noodle sheet, rolled and cut to make fresh noodles; a boiling step in which the fresh noodles are boiled at a temperature of 110°C to 130°C under a pressurized environment and then cooled to make boiled noodles; a freezing step in which the boiled noodles are frozen; and a resting step in which the frozen noodles are thawed and left to rest at 5 to 25°C for 2 hours or more. (2) The method for producing udon noodles as described in (1) above, characterized in that in the kneading process, the proportion of etherified starch and acetylated starch in the powdered raw materials is 20 to 40% by weight. (3) The method for producing udon noodles according to (1) or (2) above, characterized in that, in the boiling process, the boiling temperature is 120°C to 130°C, the pressurized environment for boiling is maintained at a pressure 5% or more higher than the boiling pressure, the noodles boiled under the same pressurized environment are cooled to 100°C or below, and then discharged to atmospheric pressure. (4) A method for improving the texture of frozen udon noodles, characterized by sequentially comprising: a kneading step of adding water to a powder raw material mainly made of wheat flour and containing either or both of etherified starch and acetylated starch, and kneading to make noodle dough; a noodle-making step of shaping the noodle dough into a noodle sheet, rolling and cutting it to make fresh noodles; a boiling step of boiling the fresh noodles at a temperature of 110°C to 130°C under a pressurized environment and then cooling them to make boiled noodles; and a freezing step of freezing the boiled noodles, wherein the frozen noodles obtained are consumed after thawing at a temperature of 5 to 25°C for at least two hours. (5) Frozen udon noodles obtained by sequentially comprising the following steps: a kneading step in which water is added to a powder raw material containing either or both etherified starch and acetylated starch, which is mainly wheat flour, and kneaded to make noodle dough; a noodle making step in which the noodle dough is formed into a noodle sheet, rolled and cut into strips to make fresh noodles; a boiling step in which the fresh noodles are boiled at a temperature of 110°C to 130°C under a pressurized environment and then cooled to make boiled noodles; and a freezing step in which the boiled noodles are frozen, and which are to be consumed after thawing at a temperature of 5 to 25°C for at least 2 hours. Other embodiments of the present invention can be exemplified below. (6) The method for producing udon noodles according to (1) above, characterized in that the powder raw material further contains activated gluten. (7) The method for producing udon noodles as described in (1) above, characterized in that the powder raw material is used as a single type of domestic "Kitahonami" wheat flour. [Effects of the Invention]

[0013] According to the present invention, the gelatinization of wheat flour-derived starch is promoted, and the viscoelasticity after time can be increased through interaction with etherified starch or acetylated starch, which originally have high gelatinization viscosity and exhibit resistance to aging. Furthermore, the viscoelasticity, which is excessively high for consumption immediately after thawing, decreases appropriately over time after thawing, leaving a viscoelasticity that is suitable for consumption 2 to 4 hours later and has an improved texture. In addition, by incorporating etherified starch or acetylated starch, the boiling of the boiling water and the boiling of the noodles themselves, which can cause roughness, are prevented in the extremely fragile boiled state, thus preserving the appearance of the boiled udon noodles. As a result, the palatability of frozen udon and other noodles consumed several hours after thawing can be improved, contributing to the improvement of the quality of noodle menus in the bento and prepared food markets. [Brief explanation of the drawing]

[0014] [Figure 1] Perspective view showing the noodle cutting test. [Figure 2] Diagram explaining the "late compression 1 / 3 area ratio" [Figure 3] Example Study-1: Graph showing the change in the 1 / 3 area ratio during the later stages of compression. [Figure 4] Example Study-2: Graph showing the change in the 1 / 3 area ratio during the later stages of compression. [Modes for carrying out the invention]

[0015] As a method for manufacturing udon of the present invention, kneading water is added to a powder raw material containing either or both of etherified starch and acetylated starch, with wheat flour as the main raw material, and kneaded to form noodle dough through kneading. Then, the noodle dough is formed into noodle sheets, rolled, and cut into strips to make fresh noodles in the noodle-making process. When boiling the fresh noodles, they are boiled and cooled at a temperature of 110°C to 130°C in a pressurized environment to make cooked noodles in the boiling process. There is no particular limitation as long as it is a method that sequentially includes a freezing process for freezing the cooked noodles and a retting process for retting the frozen noodles at 5°C to 25°C for 2 hours or more after thawing. As a method for improving the texture of frozen udon of the present invention, kneading water is added to a powder raw material containing either or both of etherified starch and acetylated starch, with wheat flour as the main raw material, and kneaded to form noodle dough through kneading. Then, the noodle dough is formed into noodle sheets, rolled, and cut into strips to make fresh noodles in the noodle-making process. When boiling the fresh noodles, they are boiled and cooled at a temperature of 110°C to 130°C in a pressurized environment to make cooked noodles in the boiling process. There is no particular limitation as long as it is a method of eating the frozen noodles obtained by sequentially including a freezing process for freezing the cooked noodles at 5°C to 25°C for 2 hours or more after thawing. As frozen udon of the present invention, kneading water is added to a powder raw material containing either or both of etherified starch and acetylated starch, with wheat flour as the main raw material, and kneaded to form noodle dough through kneading. Then, the noodle dough is formed into noodle sheets, rolled, and cut into strips to make fresh noodles in the noodle-making process. When boiling the fresh noodles, they are boiled and cooled at a temperature of 110°C to 130°C in a pressurized environment to make cooked noodles in the boiling process. There is no particular limitation as long as it is frozen udon for which a cooking method of eating it at 5°C to 25°C for 2 hours or more after thawing is specified, obtained by sequentially including a freezing process for freezing the cooked noodles.

[0016] Wheat flour suitable for the main raw material powder of the present invention can be used as long as it is a product distributed and sold as noodle flour. For example, ASW produced in Australia, and more preferably, noodle flour with domestic Kitanohonami as a single raw material is suitable because it is difficult to break down during the boiling process. Also, wheat flour mainly composed of ASW produced in Australia or Kitanohonami and blended with other wheat may be used.

[0017] The aging-resistant starches suitable for the present invention are etherified starch (hydroxypropylated starch) and acetylated starch (acetic acid starch). More preferably, they are acetylated tapioca starch and etherified tapioca starch. In addition, by adjusting the degree of substitution of acetyl groups or hydroxypropyl groups to suitable gelatinization start temperatures and gelatinization viscosities, the raw materials can be potato, sweet potato, wheat or corn. Also, in addition to the substitution of hydroxyl groups by etherification and acetylation, acetylated phosphate-crosslinked starch or etherified phosphate-crosslinked starch lightly crosslinked with phosphate can also be used. However, the degree of phosphate crosslinking should be such that it does not harden the texture of udon. The proportion of these anti-aging starches in the powder raw material is preferably 20 to 40% by weight, more preferably 30 to 35% by weight.

[0018] In the powder raw material, active gluten may be added in addition to wheat flour and starch. Active gluten can supplement the gluten derived from wheat flour that is relatively lacking due to the blending of starch, and can prevent the deterioration of noodle-making properties and noodle texture. Active gluten is a powder fractionated and dried from wheat, and any that shows elasticity and binding properties by adding water and kneading to form the framework of noodle dough can be used, but preferably it is white and nearly odorless and does not impair the flavor of noodles such as udon.

[0019] In the kneading process, salt water is generally used as the kneading water. The water addition rate is adjusted according to the characteristics of the mixer or noodle-making machine and the water absorption rate of the powder raw material. A vacuum mixer is used for the mixer to knead under a reduced pressure environment, and the preferable reduced pressure is 80 kPa or more, more preferably 90 kPa or more. The kneaded product should be in a state of a moist, homogeneous dough with a size of 3 to 10 cm, deaerated and having a transparent appearance.

[0020] The noodle-making process follows standard procedures. For handmade udon noodles, a handmade noodle-making machine is used, and the dough is rolled lengthwise and widthwise. For hand-stretched udon noodles, the dough is formed into a string shape and then stretched lengthwise. If only the thickness and shape of the noodle strands are distinctive, for example, in the case of thin udon, hiyamugi, kishimen, and somen noodles included in the present invention, a flat-roll noodle-making machine is used to form the noodle sheet, and then it is rolled. In any noodle-making process, after forming the noodle sheet, an appropriate amount of time is allowed to restore the dough's extensibility, and then subsequent rolling is performed, and fresh noodles are obtained using a knife-cutting device or a rotary cutting blade.

[0021] In the boiling process of the present invention, the process from placing the raw noodles into boiling water to starting boiling, boiling, and cooling requires that the final boiling stage, including the later boiling stage, be performed at a temperature of 110°C to 130°C under pressurized conditions. Therefore, in the boiling process of the present invention, the entire process from the start of boiling, including the pre-boiling stage, to the final boiling stage may be performed at a temperature of 110°C to 130°C under pressurized conditions, or the start of boiling, including the pre-boiling stage, may be performed at 98°C under atmospheric pressure, and the final boiling stage, including the later boiling stage, may be performed at a temperature of 110°C to 130°C under pressurized conditions. By raising the temperature at the end of the boiling process when the water content is high and water has penetrated to the center of the noodle strands, gelatinization can be performed efficiently. Since the heat transfer time to the center differs depending on the thickness of the udon noodle strands, it is preferable to boil the noodles for at least 1 minute, preferably at least 2 minutes, at a temperature of 110°C to 130°C, preferably 120°C to 130°C under pressurized conditions.

[0022] Furthermore, it is preferable to maintain the pressurized environment for boiling at a pressure at least 5% higher than the boiling pressure. In this invention, the boiling pressure is defined as the water vapor pressure with the boiling point at the boiling temperature. For example, the water vapor pressure with a boiling point of 110°C is approximately 42 kPa in gauge pressure, the water vapor pressure with a boiling point of 120°C is approximately 97 kPa in gauge pressure, and the water vapor pressure with a boiling point of 130°C is approximately 169 kPa in gauge pressure. For example, when boiling at 120°C, if you try to maintain the boiling pressure of 97kPa, boiling is unavoidable due to the temperature difference caused by the cooling of the outer circumference of the pressure vessel and the relationship with the heat source. By pressurizing by 5% or more using high-pressure air, for example, and maintaining a pressure of 110kPa, a stable state can be maintained in which boiling is moderately suppressed.

[0023] Furthermore, the cooked noodles should be cooled to below 100°C under a pressure environment at least 5% higher than the boiling pressure. By cooling them to below 100°C at a pressure that suppresses boiling, the noodles themselves will not boil when removed under atmospheric pressure. Cooling them further before removal increases the strength of the noodle strands, allowing them to withstand the water flow and transfer shocks when removed from the pressurized boiling device.

[0024] The udon noodles, removed under atmospheric pressure, are immersed in cold water to cool to below 10°C, and then frozen to obtain frozen noodles. The water content of the frozen udon noodles is preferably 65-70%, more preferably 66-69%.

[0025] This invention relates to a method for producing frozen noodles specifically for consumption two hours or more after thawing. The frozen noodles obtained according to this invention may be thawed by running water, natural thawing, or hot water thawing. If thawed with hot water, cool to below room temperature with cooling water. In all cases, the thawed noodles should be drained of water as needed and divided into serving units. The viscoelasticity of the frozen noodles obtained according to this invention will gradually ease over time if left to rest at 5-25°C for two hours or more after thawing. The noodles will exhibit an appropriate texture after a resting process of two to six hours at 5-25°C after thawing. The timing of consumption can be determined according to the user's convenience. For example, if the noodles are sold at low temperatures under appropriate hygiene management and consumed after heating, they may be consumed six hours later, for example, eight hours, ten hours, or even twelve hours later. [Examples]

[0026] The effects of the present invention are shown in Examination-1 to 3, but the present invention is not limited to these contents.

[0027] <Consideration-1> In Study-1, a formulation model of etherified tapioca starch boiled at 98-99°C under atmospheric pressure was used as a control, and the effect of improving texture over time was confirmed in an example where the boiling conditions were 120°C under a pressurized environment.

[0028] Preparation of frozen boiled udon noodles The powder ingredients consist of 67% by weight of domestically produced "Kitahonami" single wheat flour, 33% by weight of etherified tapioca starch "Matsutani Yuri (Matsutani Chemical Industry Co., Ltd.)" and 3% by weight of activated gluten "A-Glu AS (Glico Nutrition Foods Co., Ltd.)". Furthermore, the starch content was set at 33% as a reasonable limit, because increasing the amount of starch significantly reduces noodle-making workability, flavor, and ease of separating noodles during consumption, particularly between 30% and 40%. Also, all units "%" listed in Table 1 refer to mass percent.

[0029] [Table 1]

[0030] In Study-1, 3 kg of the powdered raw materials listed in Table 1 were placed in a vacuum mixer, kneading water was added, and the mixture was kneaded at high speed for 2 minutes, then at low speed for 5 minutes under reduced pressure (gauge pressure) of 80-85 kPa, resulting in a homogeneous dough with particle sizes of 2-8 cm and a temperature of 30°C. The kneaded dough was then compounded after forming into a noodle sheet, and left to rest for 30 minutes as a 10 mm thick noodle sheet. After two stages of rolling, it was shredded with a rotary cutting blade equivalent to No. 9, yielding fresh noodles with a thickness of 3.0-3.3 mm and a length of 30 cm.

[0031] The boiling conditions involved using a pressurized kettle equipped with a steam stirring function and a jacket-type heating function, with cooling water supplied from both the bottom and top of the kettle as needed. The boiling times were set to 7 minutes and 10 minutes. In the 10-minute boiling experiment (1), the raw noodles were placed in a basket of hot water stirred with steam and loosened. They were boiled at 98°C under atmospheric pressure for 5 minutes, then heated for 3 minutes in a sealed, pressure-resistant state to reach 120°C, which was maintained for 1 minute. After that, cooling water was injected from the bottom of the kettle and stirred to cool to around 90°C. Then, cooling water was injected from the top, the pressure was restored in about 1 minute, and the noodles were removed. In the 7-minute boiling experiment (1), the procedure was the same as the 10-minute boiling experiment, except that the boiling time at 98°C under atmospheric pressure was changed from 5 minutes to 2 minutes, and the noodles were removed.

[0032] The control group was boiled for only 10 minutes. The control group used the same pot as in Experiment 1, and after adding and loosening the raw noodles, the noodles were removed while maintaining a temperature of 98-99°C under atmospheric pressure. In both trial groups, the boiled noodles were cooled in 5°C cold water, drained, and then frozen in 100g portions in freezing trays to produce frozen noodles.

[0033] Sensory evaluation test The prepared frozen noodles were thawed under running water at a later date, and sensory evaluation was conducted after 4 hours at 10°C following thawing. Scoring was done on a scale of 0 to 10 points, with the control udon noodles being set at a baseline of 5 points. The evaluation items were three: degree of hardness (higher scores for harder noodles), viscoelasticity (higher scores for chewy texture), and overall texture (higher scores for pleasant texture). Four panelists evaluated the noodles, and the average score was calculated.

[0034] [Table 2]

[0035] The "1-10 minute boiling" method showed no difference from the control in terms of firmness, an average score of 6.5 for viscoelasticity (degree of chewiness), and an average score of 6.8 for overall texture (pleasantness). Both viscoelasticity and overall texture were clearly superior, with all panelists scoring 6 or higher compared to the control's 5. The "1-7 minute boiling" method showed a high average score of 6.8 for firmness compared to the control's 5, an average score of 6.0 for viscoelasticity, and an average score of 6.3 for overall texture. While the scores for viscoelasticity and overall texture were close to those of the "1-10 minute boiling" method, there was variation in scoring among panelists, ranging from 4 to 8. From the results of the "1-10 minute boiling" trial, frozen noodles boiled under pressure at 120°C had superior texture 4 hours after thawing compared to those boiled at atmospheric pressure at 98-99°C. Furthermore, in terms of appearance, such as roughness of the noodle strands, there was no significant difference across all test categories.

[0036] Noodle cutting test The noodle cutting test was performed using a texture analyzer (manufactured by Shimadzu Corporation). Frozen noodles were placed in a container, tap water was poured in and blown over, and the amount of water was adjusted so that the entire noodle would thaw in 10 minutes. The noodles were measured five times each after thawing, when the noodle temperature had stabilized at 10°C, and again after draining the water using a sieve, transferring the noodles to a plate, covering with plastic wrap, and storing at 10°C, then adding 50 ml of water per 100 g of noodles to loosen them, and measuring the noodle temperature five times.

[0037] Measurements were taken by compressing the noodles using the pressure-sensitive axis shown in Figure 1. The noodles were cut into approximately 5 cm sections and placed on a sample stand perpendicular to the pressing part of the pressure-sensitive axis. The sample stand was raised at a rate of 1 mm per second, and stress was recorded at intervals of 0.1 seconds or less. The proportion of the area formed between the recorded stress-deformation curve and the horizontal axis at stress 0, which shows the compression process, occupied by the last 1 / 3 of the compression process was defined as the "late compression 1 / 3 area ratio" and used as an indicator of the quality of the texture.

[0038] The above-mentioned "1 / 3 area ratio in the late compression stage" is explained using the stress-deformation curve model in Figure 2. Point A is the starting point of the stress-deformation curve, where the noodle wire placed on the sample stand rises and makes contact with the pressure-sensitive axis, which is fixed in a vertically suspended state. The sample stand passes through A at a constant velocity, compressing the noodle wire. As a result, the stress increases, and when the strain reaches its limit, the stress-deformation curve forms a peak and the stress decreases. Subsequently, point C, where the sample stand makes contact with the pressure-sensitive axis, is the endpoint of the stress-deformation curve. The "1 / 3 area ratio in the late compression stage" is the ratio of the area formed in section BC (shown in shaded area) within the area formed in section AC, which is 1 / 3 of the late compression stage, by vertically dividing the area formed in section AC by section AC at position B, which is divided in a 2:1 ratio. Generally, in stress deformation curve models immediately after thawing, which result in a good texture, the "late 1 / 3 area ratio of compression" is high, while in stress deformation curve models after a period of time has passed since thawing, which generally result in a poorer texture, the "late 1 / 3 area ratio of compression" is low. A high "late 1 / 3 area ratio of compression" is an indicator of a good texture. The reason for adopting the "late 1 / 3 area ratio of compression" as a texture index from the stress deformation curve is that, because this invention evaluates noodles after a period of time has passed since thawing frozen noodles, the stress deformation curves for each compression become uneven and the peak coordinates tend to fluctuate due to the homogenization of moisture and aging of starch components that occur during storage for 4 to 6 hours. As a result, no significant difference could be obtained with an index based on peak coordinates, making statistical evaluation difficult.

[0039] Furthermore, in Study-1, in order to more fairly compare the time-dependent changes in the "late compression 1 / 3 area ratio" between the control and Experiment 1, we used the water content equivalent values ​​of the "late compression 1 / 3 area ratio" converted to the same water content as the control, based on the water content and values ​​of the 7-minute and 10-minute boiling times in Experiment 1. Furthermore, to test the difference between the mean values ​​of Experiment 1 and the control, the probability of following a T-distribution between each of the 7-minute and 10-minute boiling times in Experiment 1 and the control was calculated under the conditions of a "two-tailed distribution with unequal variances" and used as the judgment index.

[0040] [Table 3]

[0041] The results for the "late compression 1 / 3 area ratio" are shown in Table 3. In Table 3, under the "Implementation 1" trial category, the columns for 7-minute boiling and 10-minute boiling show the average value (n=5) obtained from 5 cutting tests, as well as the "probability of following a t-distribution" between each of the 7-minute and 10-minute boiling methods and the "control." The "moisture content equivalent value" column shows the "late compression 1 / 3 area ratio" converted to the same moisture content as the "control." In the "control" group, the moisture content decreased from 78.7% immediately after thawing to below 70% between 2 and 6 hours later, whereas in "test 1," the moisture content was 84.1% (moisture equivalent) immediately after thawing, and remained between 75.2% and 74.2% between 2 and 6 hours later, maintaining a value relatively close to the "control" group's value of 78.7% immediately after thawing. Furthermore, the "probability of following the t-distribution" was 5% or less at 2, 4, and 6 hours after boiling for both 7 minutes and 10 minutes, and a significant difference was observed between the "control" and "implementation 1".

[0042] Study-1 showed that frozen udon noodles boiled under pressure at 120°C had superior texture four hours after thawing compared to those boiled at 98-99°C under atmospheric pressure. The suppression of quality deterioration over time was supported by the "late compression 1 / 3 area ratio" from the stress deformation curve of the cutting test.

[0043] <Consideration-2> In Study-2, we confirmed the effect of maintaining texture when the proportion of etherified tapioca starch used in the formulation was reduced.

[0044] Preparation of frozen boiled noodles As shown in Table 4, frozen udon noodles were prepared by reducing the etherified tapioca starch content from Study-1 to 20% (Implementation 2) and 10% (Comparison 1). The noodle-making and boiling conditions were the same as in Study-1, "Implementation 1 - 10 minutes boiling."

[0045] [Table 4]

[0046] Sensory evaluation test The prepared frozen noodles were thawed under running water at a later date, and a sensory evaluation was conducted after 4 hours at 10°C following thawing. In the sensory evaluation of Study-2, "flavor preference" was added to the evaluation items of Study-1, and the "control" from Study-1 was used as the evaluation criterion, including the 10-minute boiled udon from "Implementation 1". The scoring method and panelists were the same as in Study-1.

[0047] [Table 5]

[0048] "Implementation 2" scored an average of 6.3 points for hardness, higher than "Implementation 1," while viscoelasticity and overall texture both averaged 4.8 points, and flavor preference was 5.3 points, roughly equivalent to "Control." "Comparison 1" scored an average of 7.5 points for hardness, higher than "Implementation 2," while viscoelasticity averaged 2.3 points, overall texture averaged 2.8 points, lower than "Control" and "Implementation 2," and flavor preference was high at 5.5 points, with half of the panelists giving it a score of 6. Furthermore, the scoring for "Implementation 1," which was re-evaluated, showed a generally similar trend to "Consideration-1." Based on the results of "Experiment 2," the texture of frozen udon noodles containing 20% ​​etherified tapioca starch, boiled under pressure at 120°C, was equivalent to that of frozen udon noodles containing 30% etherified tapioca starch, boiled normally at 98°C, in the evaluation conducted 4 hours after thawing.

[0049] Cutting test using a texture analyzer The noodle cutting test was conducted in the same manner as in Study-1, and the "1 / 3 area ratio after compression" was determined as a texture index from the obtained stress-deformation curve and compared.

[0050] [Table 6]

[0051] The results for the "1 / 3 area ratio in the later stages of compression" are shown in Table 6, and the graph is shown in Figure 4. For comparison, the values ​​for "Implementation 1 (10 minutes boiling)" are also shown in the graph. While the "control" group's percentage decreased to below 70% between 2 and 6 hours, "implementation 2" maintained a higher percentage than the "control" group from 81.4% immediately after thawing to 73.7% after 2 hours, 70.8% after 4 hours, and 69.7% after 6 hours. Furthermore, it showed a statistically significant difference between the two groups at 2 and 4 hours. "Comparison 1" showed a value of 80.8% immediately after thawing, similar to "Implementation 2," but decreased in the interval between 2 and 6 hours, and did not show a significant difference compared to the "Control" group.

[0052] Study 2 showed that in order to maintain the texture of the control frozen udon noodles, which were boiled at 98°C with 30% etherified tapioca starch added, 2-4 hours after thawing, it is possible to reduce the amount of etherified tapioca starch from 30% to 20% by boiling them at 120°C under pressure.

[0053] <Consideration-3> In Study-3, the etherified tapioca starch used in Study-1 was replaced with acetylated tapioca starch, bleached tapioca starch, and waxy corn starch, and the effect of maintaining texture was compared.

[0054] Preparation of frozen boiled noodles As shown in Table 7, in the trial production category "Implementation 3," which used acetylated tapioca starch "Sakura-2 (Matsutani Chemical Industry)," in "Comparison 2," bleached tapioca starch "MKK-100 (Matsutani Chemical Industry)" was used, and in "Comparison 3," waxy corn starch "Nisshoku Waxy Starch Y (Nippon Shokuhin Kako)" was used to prepare frozen udon noodles. The noodle-making conditions and boiling conditions were the same as in Study-1 "Implementation 1 - 10 minutes boiling."

[0055] [Table 7]

[0056] Sensory evaluation test The prepared frozen noodles were thawed under running water at a later date, and sensory evaluation was performed after 4 hours at 10°C following thawing. In the sensory evaluation of Study-3, two evaluation criteria were established: the "control" udon from Study-1 was given a base score of 0, and the "execution 1 (boiled for 10 minutes)" udon from Study-1 was given a base score of 5. The evaluation items were narrowed down to two items: viscoelasticity and overall texture, and scores were given for "execution 3," "comparison 2," and "comparison 3."

[0057] [Table 8]

[0058] "Implementation 3" scored an average of 4.8 points for viscoelasticity (degree of chewiness) and an average of 4.5 points for overall texture (likability), which was roughly equivalent to "Implementation 1". In "Comparison 2," the viscoelasticity score averaged 2 points and the overall texture score averaged 2.3 points. "Comparison 2" was clearly lower than "Implementation 1," and each panelist's score included the same 0 points as the control group. In "Comparison 3," the viscoelasticity score averaged 1.8 points and the overall texture score averaged 1.3 points. "Comparison 3" was clearly lower than Implementation 1 and also lower than Comparison 2.

[0059] Study 3 showed that frozen udon noodles containing acetylated tapioca starch, like those containing etherified tapioca starch, exhibited suppressed deterioration in texture after 4 hours of thawing when boiled under pressure at 120°C, compared to those boiled at atmospheric pressure at 98-99°C. On the other hand, bleached tapioca starch and waxy corn starch did not show such an effect, indicating that the effect of suppressing deterioration in texture over time is a common effect of etherified and acetylated starch, which are starches resistant to aging.

Claims

1. A method for producing udon noodles, characterized by comprising, in sequence, a kneading step in which water is added to a powder raw material containing either or both etherified starch and acetylated starch, which is mainly wheat flour, and kneaded to form noodle dough; a noodle-making step in which the noodle dough is formed into a noodle sheet, rolled and cut to form fresh noodles; a boiling step in which the fresh noodles are boiled at a temperature of 110°C to 130°C under a pressurized environment and then cooled to form boiled noodles; a freezing step in which the boiled noodles are frozen; and a resting step in which the frozen noodles are thawed under running water and then left to rest at 5 to 25°C for 2 to 6 hours, wherein in the kneading step, the proportion of etherified starch and acetylated starch in the powder raw material is 20 to 40% by weight, and the cooking method is specified to be for consumption after 2 to 6 hours have elapsed at 5 to 25°C after thawing.

2. The method for producing udon noodles according to claim 1, characterized in that, in the boiling process, the boiling temperature is 120°C to 130°C, the pressurized environment for boiling is maintained at a pressure 5% or more higher than the boiling pressure, the noodles boiled under the same pressurized environment are cooled to 100°C or below, and then discharged to atmospheric pressure.

3. A method for improving the texture of frozen udon noodles, comprising the following steps in sequence: a kneading step in which water is added to a powder raw material containing either or both etherified starch and acetylated starch, which is made from wheat flour as the main raw material, and kneaded to form noodle dough; a noodle-making step in which the noodle dough is formed into a noodle sheet, rolled and cut to form fresh noodles; a boiling step in which the fresh noodles are boiled at a temperature of 110°C to 130°C under a pressurized environment and then cooled to form boiled noodles; and a freezing step in which the boiled noodles are frozen, wherein in the kneading step the proportion of etherified starch and acetylated starch in the powder raw material is 20 to 40% by weight, and the frozen noodles are consumed after being thawed in running water and left at 5 to 25°C for 2 to 6 hours.

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