Method for producing buckwheat flour that retains or enhances the green color, or reduces the redness.

Abstract

To provide buckwheat flour and a buckwheat processed product having high evaluation on a taste thereof, in which a green color of husked buckwheat or wholegrain buckwheat is held or enhanced, or redness is mitigated.SOLUTION: Husked buckwheat or wholegrain buckwheat is treated with processes including a blanching step of immersion in water at 50 to 100°C for 1 to 180 seconds so as to manufacture buckwheat flour with a green color held or enhanced, or redness mitigated.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a method for producing buckwheat flour in which green color is retained or enhanced, or redness is reduced, to buckwheat flour and processed buckwheat products in which green color is retained or enhanced, or redness is reduced, to a method for retaining or enhancing green color, or reducing redness, of buckwheat flour, to a method for preventing color tone change during storage of peeled buckwheat kernels, unhulled buckwheat or buckwheat flour, and to a method for removing off-flavor from buckwheat flour and improving the taste of buckwheat flour. [Background Art]

[0002] Buckwheat is an annual plant of the genus *Fagopyrum* in the family Polygonaceae, believed to have originated in Yunnan Province, southern China. In Japan, buckwheat noodles (hereinafter referred to as "soba") made from buckwheat flour obtained by milling buckwheat seeds are widely popular. In addition to their unique taste and aroma, the texture and appearance of soba are important factors that determine the quality of soba. In particular, high-quality soba is considered to have no redness and exhibit a greenish hue. Peeled kernels obtained by dehulling harvested buckwheat seeds have a green color derived from chlorophyll contained in the seed coat, and the intensity of this green color serves as an indicator of freshness. Peeled kernels obtained by dehulling seeds of so-called new buckwheat harvested immediately after harvest have particularly vivid green color, and buckwheat flour obtained by milling such peeled kernels is greenish and is highly evaluated by processors and consumers. However, depending on the post-harvest storage conditions, storage period, and processing method for buckwheat seeds, the green color derived from chlorophyll is lost due to deterioration of the peeled kernels. Such peeled kernels and buckwheat flour obtained by milling them lose their green color, become reddish, and receive lower evaluations from processors and consumers. Furthermore, soba produced from buckwheat flour with low appearance evaluation tends to have lower evaluations for taste, aroma and texture due to the influence of the appearance evaluation, and there has been a demand for a method for improving the appearance of soba.

[0003] Regarding prior art relating to the appearance of food, particularly its green color, Patent Document 1 describes a method for processing and mass-producing green whole grains, characterized by a blanching process in which green whole grains, before the yellow ripening stage, are steamed in water or steam at a temperature range of 88-102°C for 30-120 seconds, followed by a drying process. This document targets grains other than buckwheat as green whole grains, such as glutinous hulless barley, two-row barley, and gungan wheat, and the method is a processing method for making green whole grains, before the yellow ripening stage, edible, and is not intended to improve the color of the grains. That's not the case.

[0004] Regarding buckwheat, prior art using a blanching process is disclosed in Patent Document 2, which describes a method for producing buckwheat flour by treating hulled buckwheat with saturated steam and then milling it. However, this method is intended to reduce the number of bacteria, and not to improve color, prevent deterioration of color over time, or enhance taste. Furthermore, Patent Document 3 discloses buckwheat flour and a method for producing buckwheat flour that can prepare boiled buckwheat noodles and cooked buckwheat noodles that maintain the texture of freshly boiled noodles as much as possible, including a heating step. However, this method is not intended to improve color, prevent deterioration of color over time, or enhance taste. In Patent Document 3, "water bath" is given as an example of a heating method, but the conditions are described as a temperature of 70 degrees Celsius for 2 hours.

[0005] Regarding the maintenance of the green color of vegetable and plant leaves through blanching, Patent Documents 4, 5, and 6 describe the process. However, all of these documents concern methods for maintaining the green color of green vegetables and plant leaves, and it was not known that blanching of hulled buckwheat or buckwheat groats is also effective in improving the color of buckwheat flour. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2012-200726 (Japanese Patent Application No. 2011-256268) [Patent Document 2] Japanese Patent Application Publication No. 7-834 (Patent Application No. 5-170926) [Patent Document 3] Japanese Patent Publication No. 2019-118269 (Japanese Patent Application No. 2017-253011) [Patent Document 4] Japanese Patent Publication No. 2018-7588 (Japanese Patent Application No. 2016-137130) [Patent Document 5] Japanese Patent Publication No. 2007-252340 (Japanese Patent Application No. 2006-84235) [Patent Document 6] Japanese Patent Publication No. 2009-131201 (Japanese Patent Application No. 2007-310158) [Overview of the project] [Problems that the invention aims to solve]

[0007] The present invention provides buckwheat flour and buckwheat processed products that maintain or enhance the green color, reduce the redness, and have a high taste rating, using hulled buckwheat or buckwheat with a green surface, which is an indicator of fresh buckwheat seeds, or hulled buckwheat or buckwheat that has turned reddish due to deterioration. [Means for solving the problem]

[0008] As a result of their research to solve the above problems, the present inventors have found that by blanching hulled buckwheat seeds or buckwheat hulls, the green color of the hulled seeds is maintained or enhanced, or the reddish color of the hulled seeds is improved. By using buckwheat flour made from these hulled seeds, it is possible to provide buckwheat flour and buckwheat processed products that are highly rated in appearance and taste, thus completing the present invention.

[0009] The present invention is defined by the following: [1] A method for producing buckwheat flour that retains or enhances the green color or reduces the redness, characterized by processing hulled buckwheat or unhulled buckwheat including at least a blanching step. [2] The manufacturing method according to [1], wherein the blanching step is a step of immersing in water at 50 to 100°C for 1 to 180 seconds. [3] The manufacturing method according to [2], wherein the blanching step is a step of immersing in water at 80 to 100°C. [4] The manufacturing method according to [2] or [3], wherein the blanching step is a step of immersing in water for 1 to 120 seconds. [5] The manufacturing method according to [1] to [4], further comprising a cooling step and a drying step. [6] The manufacturing method according to [5], wherein the cooling temperature in the cooling step is 30°C or less. [7] The buckwheat flour having a dry color a* value that is at least 0.1 smaller than the dry color a* value of untreated buckwheat flour. [8] Buckwheat flour, wherein the change between the dry color a*1 value of buckwheat flour and the dry color a*2 value after storing the buckwheat flour at room temperature for 60 days is as follows. a*2 value - a*1 value < 0.20 Buckwheat products made using buckwheat flour as described in [9], [7], or [8].

[10] A method for maintaining or enhancing the green color of buckwheat flour obtained from hulled buckwheat or buckwheat, characterized by processing the hulled buckwheat or buckwheat including at least a blanching step.

[11] A method for preventing discoloration of hulled buckwheat or buckwheat flour obtained from hulled buckwheat or buckwheat flour during storage, characterized by processing the hulled buckwheat or buckwheat including at least a blanching step.

[12] A method for removing off-flavors from buckwheat flour obtained from hulled buckwheat or buckwheat, and improving the taste, characterized by processing the hulled buckwheat or buckwheat including at least a blanching step. [Effects of the Invention]

[0010] According to the present invention, by processing hulled buckwheat or buckwheat including at least a blanching step, it is possible to maintain or enhance the green color of the hulled buckwheat, which is a characteristic of fresh buckwheat seeds, or reduce the redness of the hulled buckwheat, which is a characteristic of deteriorated buckwheat seeds, thereby providing buckwheat flour and buckwheat processed products with a highly desirable appearance obtained by milling such hulled buckwheat. Furthermore, by processing hulled buckwheat or buckwheat including at least a blanching step, it is also possible to simultaneously prevent changes in the color of the buckwheat flour during storage and to remove off-flavors, thereby improving the taste. [Modes for carrying out the invention]

[0011] One aspect of the present invention provides a method for improving the color tone of buckwheat flour obtained by milling hulled buckwheat seeds, by maintaining or enhancing the green color of the surface of hulled buckwheat seeds, which is an indicator of fresh buckwheat seeds, or by reducing the redness of deteriorated hulled buckwheat seeds, characterized by a process that includes a blanching step of immersing the hulled buckwheat seeds in hot water at 50 to 100°C for 1 to 180 seconds. The aspects will be described in detail below.

[0012] There are no particular restrictions on the buckwheat seed variety or origin used in this invention. For example, possible raw material varieties include Shinano No. 1 and Kitawase buckwheat. Possible raw material origins include Nagano Prefecture, Hokkaido, the United States, Russia, and China. Furthermore, there is no problem if raw materials of different varieties and origins are mixed together.

[0013] The blanching step refers to short-time heating, and generally any heating means may be used. However, in the present invention, the heating means is "blanching" with heated water, which refers to immersing or passing the material in heated water. In the present invention, the heating temperature is in the range of 50 to 100°C, more preferably in the range of 80 to 100°C. The heating time is in the range of 1 to 180 seconds, preferably 1 to 120 seconds, more preferably 1 to 60 seconds, and still more preferably 1 to 30 seconds. If the heating temperature is lower than the above range, there is a risk that the green color retention and enhancement effects and the red tone improvement effect are less likely to be obtained. Further, even if the heating time is set longer than the above range, the green color retention and enhancement effects and the red tone improvement effect can still be obtained, but in addition to incurring extra cost and time, the peeled grains swell and change shape, and starch in the peeled grains gelatinizes to increase the viscosity of the peeled grains, which degrades operability after the heating step and may cause problems from the perspective of productivity.

[0014] The cooling step after heating in the blanching step of the present invention is intended to prevent the green pigment from turning brown due to residual heat after heating. The cooling temperature is preferably 30°C or lower, more preferably 16°C or lower. There are no particular limitations on the cooling means, and examples include cooling by immersion in a cooling water tank equipped with a chiller unit.

[0015] The drying step in the present invention aims to dry buckwheat peeled grains or unhulled buckwheat, whose color tone has been improved by the above treatment, to a predetermined moisture content, so that the product is brought into a state suitable for the subsequent milling step and other processing. There are no particular limitations on the drying means, and examples include a hot air dryer.

[0016] It has been confirmed that the treatment including the blanching step of the present invention not only improves the color tone of peeled buckwheat grains or unhulled buckwheat, but also improves the color tone of buckwheat flour obtained by milling the buckwheat grains or unhulled buckwheat treated in this way. Although the improvement in the color tone of buckwheat flour varies depending on the color tone of peeled buckwheat grains or unhulled buckwheat, the dry color a* value of buckwheat flour obtained by milling peeled buckwheat grains or unhulled buckwheat treated through the treatment including the blanching step of the present invention is at least 0.1 lower than the dry color a* value of buckwheat flour obtained by milling peeled buckwheat grains or unhulled buckwheat not subjected to the treatment including the blanching step of the present invention. Here, the dry color a* value of buckwheat flour refers to the value of the a* coordinate in the CIE1976 (L*, a*, b*) color space. Negative values are closer to green, and positive values are closer to red (magenta). Therefore, a smaller dry color a* value of buckwheat flour means stronger greenness and weaker redness.

[0017] Furthermore, it has been confirmed that the improved color tone of buckwheat flour obtained by milling peeled buckwheat grains treated by the treatment including the blanching step of the present invention is maintained even during storage of the buckwheat flour. In terms of maintaining the improved color tone, the change in dry color a* was less than 0.20 even after 60 days of storage under the storage condition of 30°C. Since the improved color tone is maintained during storage of buckwheat flour, there is sufficient flexibility in selecting the timing for processing buckwheat flour.

[0018] The peeled buckwheat grains or unhulled buckwheat obtained according to the present invention can be processed without particular limitations as equivalent to peeled buckwheat grains or unhulled buckwheat not subjected to the treatment according to the present invention. For example, compared with buckwheat flour obtained by milling untreated peeled buckwheat grains or unhulled buckwheat, the buckwheat flour obtained through a milling process retains or enhances greenness, reduces redness, has less color tone deterioration during storage, and has reduced off-flavors. There are no particular limitations on the milling method, and milling can be performed using commonly used equipment for buckwheat milling, such as roller mills, stone mills, impact crushers, and the like. The obtained buckwheat flour can be processed into buckwheat processed products without any particular limitations, for example, it can be processed into noodles, buckwheat cakes, and other buckwheat products.

[0019] The present invention will be described below with reference to examples, but the present invention is not limited in any way by the following examples. [Examples]

[0020] [Experiment 1] (Investigation of heating time) Hulled buckwheat (from China) and unhulled buckwheat (from China) were immersed in boiling water for a specified time, then cooled in 16°C running water for approximately 10 seconds, and dried until the moisture content was equivalent to that before treatment. The obtained hulled buckwheat and unhulled buckwheat were ground using an ultracentrifugal mill (Lech ZM200) under specified conditions to obtain buckwheat flour. For unhulled buckwheat, the hulls were removed, the grains were hulled, and then ground under specified conditions to obtain buckwheat flour. The color tone of the obtained buckwheat flour was measured using a colorimeter (Nippon Denshoku SE7700). The test conditions for the examples and comparative examples in Test 1, and the color tone data of the obtained buckwheat flour are shown in Table 1 below.

[0021] [Table 1]

[0022] In the table, the dry color a* value is the value obtained by packing the granulated buckwheat flour into a predetermined container and measuring it, while the wet color a* value is the value obtained by packing the buckwheat flour into a predetermined container, immersing it in water for 30 seconds, and measuring it in a moistened state. When the color tone of buckwheat flour obtained by grinding dried hulled buckwheat and unhulled buckwheat under predetermined conditions was measured, it was observed that in all examples, the a* value decreased, the green color increased, and the redness decreased compared to buckwheat flour obtained by grinding untreated hulled buckwheat and unhulled buckwheat, and the effect was more pronounced with longer heating times. The heating temperature is listed as 98°C as an actual measured value, but this result was obtained using boiling water.

[0023] [Experiment 2] (Investigation of heating temperature) Hulled buckwheat (from China) and whole buckwheat (from China) were immersed in water adjusted to a predetermined temperature for 60 seconds for the hulled buckwheat and 90 seconds for the whole buckwheat. After immersion, they were cooled in 16°C running water for approximately 10 seconds and dried until their moisture content was equivalent to that before processing. The obtained hulled buckwheat and whole buckwheat were then ground using an ultracentrifugal mill (Lech ZM200) under predetermined conditions to obtain buckwheat flour. For the whole buckwheat, the hulls were removed, and the grains were hulled before being ground under predetermined conditions to obtain buckwheat flour. The color tone of the obtained buckwheat flour was measured using a colorimeter (Nippon Denshoku SE7700). The test conditions for the examples and comparative examples in Test 2, and the color tone data of the obtained buckwheat flour are shown in Table 2 below.

[0024] [Table 2]

[0025] The color of buckwheat flour obtained by grinding dried hulled buckwheat and unhulled buckwheat under predetermined conditions was measured. For unhulled buckwheat, the hulls were removed and the grains were ground. As a result, compared to buckwheat flour obtained by grinding untreated hulled buckwheat and unhulled buckwheat, all examples showed a decrease in the a* value, an increase in green color, and a decrease in redness. In both cases of hulled buckwheat and unhulled buckwheat, the effect was more pronounced with higher heating temperatures.

[0026] [Experiment 3] (Investigation of cooling temperature) Hulled buckwheat (from China) and whole buckwheat (from China) were immersed in boiling water for a predetermined time, then cooled to a predetermined temperature and dried until the moisture content was equivalent to that before processing. The obtained hulled buckwheat and whole buckwheat were ground using an ultracentrifugal mill (Lech ZM200) under predetermined conditions to obtain buckwheat flour. For whole buckwheat, the hulls were removed, and the buckwheat was ground after being hulled. The color tone of the obtained buckwheat flour was measured using a colorimeter (Nippon Denshoku Kogyo SE7700). The test conditions for the examples and comparative examples in Test 3, and the color tone data of the obtained buckwheat flour are shown in Table 3 below.

[0027] [Table 3]

[0028] The color of buckwheat flour obtained by grinding dried hulled buckwheat and unhulled buckwheat under predetermined conditions was measured. Compared to buckwheat flour obtained by grinding untreated hulled buckwheat and unhulled buckwheat, the a* value decreased in all examples. Furthermore, a tendency was observed for the a* value to decrease as the cooling temperature decreased, the green color to intensified, and the redness to decrease. However, at cooling temperatures of 30°C or below, the effect did not change significantly, especially in terms of the wet color a* value.

[0029] [Test 4] (Examination of changes in color tone over time) Hulled buckwheat groats (from China) were immersed in boiling water for a predetermined time, then cooled to a predetermined temperature and dried until their moisture content was equivalent to that before processing. The obtained hulled groats were ground using an ultracentrifuge (Lech ZM200) under predetermined conditions to obtain buckwheat flour. The color of the obtained buckwheat flour was measured using a colorimeter (Nippon Denshoku SE7700) at 0, 60, and 90 days to evaluate the change in color during storage. Each batch of buckwheat flour was stored at room temperature. The test conditions for the examples and comparative examples in Test 4, as well as the color data of the obtained buckwheat flour, are shown in Table 4 below.

[0030] [Table 4]

[0031] The color changes of buckwheat flour obtained by grinding dried hulled buckwheat under predetermined conditions were measured during storage. The results showed that, compared to buckwheat flour obtained by grinding untreated hulled buckwheat, the change in a* value was smaller in all examples, and the enhanced green color and reduced redness tended to be maintained. This tendency was maintained for at least 90 days of storage. In the buckwheat flour obtained from the treated hulled buckwheat of the present invention, the change in the dry color a* value was 0 after 30 days of storage, 0.11 after 60 days of storage, and 0.28 after 90 days of storage. On the other hand, in the case of buckwheat flour obtained from untreated hulled buckwheat, the change in the dry color a* value was 0.20 after 30 days of storage, 0.31 after 60 days of storage, and 0.49 after 90 days of storage.

[0032] [Test 5] (Examination of taste improvement) Hulled buckwheat (from China) and whole buckwheat (from China) were immersed in boiling water for a specified time, then cooled to a specified temperature and dried until the moisture content was equivalent to that before processing. The obtained hulled buckwheat and whole buckwheat were then ground using an ultracentrifugal mill (Lech ZM200) under specified conditions to obtain buckwheat flour. For whole buckwheat, the hulls were removed, and the buckwheat was ground after being hulled. Using the obtained buckwheat flour, raw soba noodles were made under the following noodle-making conditions, and sensory evaluation was conducted by 10 panelists. The sensory evaluation items were taste, texture, and overall evaluation, with the untreated product set as standard (3 points), slightly better (4 points), good (5 points), slightly worse (2 points), and worse (1 point). The results are shown in Table 5 below. Noodle making conditions: 50% buckwheat flour, 50% wheat flour (medium-strength flour), 32% water.

[0033] [Table 5]

[0034] Buckwheat flour obtained by grinding dried hulled buckwheat and unhulled buckwheat under specified conditions showed not only improved color compared to buckwheat flour obtained from untreated hulled buckwheat and unhulled buckwheat, but also demonstrated remarkable improvements in taste, texture, and overall sensory evaluation. [Industrial applicability]

[0035] The present invention provides buckwheat flour that retains or enhances the green color, or reduces redness, and a method for producing the same, which makes it possible to provide buckwheat flour and buckwheat processed products that are highly regarded in terms of appearance. In addition, it is possible to provide buckwheat processed products that suppress changes in color over time during storage, have less off-flavors, and have a superior taste.

Claims

1. A method for producing buckwheat flour that retains or enhances the green color, reduces the redness, or improves the taste, characterized by a blanching step in which hulled buckwheat or unhulled buckwheat is immersed in water at least 50 to 100°C for 1 to 180 seconds.

2. The manufacturing method according to claim 1, wherein the blanching step is a step of immersing in water at 80 to 100°C.

3. The manufacturing method according to claim 1 or 2, wherein the blanching step is a step of immersing in water for 1 to 120 seconds.

4. Furthermore, the manufacturing method according to any one of claims 1 to 3, further comprising a cooling step and a drying step.

5. The manufacturing method according to claim 4, wherein the cooling temperature in the cooling step is 30°C or lower.

6. Buckwheat flour having a dry color a* value at least 0.1 lower than the dry color a* value of buckwheat flour before the blanching process, which includes a blanching step of immersing hulled buckwheat or unhulled buckwheat in water at least 50 to 100°C for 1 to 180 seconds, thereby retaining or enhancing the green color, reducing the redness, or improving the taste of buckwheat flour.

7. The buckwheat flour according to claim 6, wherein the change between the dry color a*1 value of the buckwheat flour and the dry color a*2 value after storing the buckwheat flour at room temperature for 60 days has the following relationship. a*2 value - a*1 value < 0.20

8. A soba noodle product using the soba flour described in Claim 6 or 7.

9. A method for maintaining or enhancing the green color of buckwheat flour obtained from hulled buckwheat or buckwheat, characterized by a blanching step in which the hulled buckwheat or buckwheat is immersed in water at a temperature of at least 50 to 100°C for 1 to 180 seconds, thereby reducing the reddish color.

10. A method for preventing discoloration of hulled buckwheat or buckwheat flour obtained from hulled buckwheat or buckwheat flour during storage, characterized by a blanching step in which the hulled buckwheat or buckwheat is immersed in water at a temperature of at least 50 to 100°C for 1 to 180 seconds.

11. A method for improving the taste of buckwheat flour obtained from hulled buckwheat or buckwheat, characterized by a blanching step in which the hulled buckwheat or buckwheat is immersed in water at a temperature of at least 50 to 100°C for 1 to 180 seconds.

Images