Polished rice

Abstract

To provide polished rice that has high nutritional value and exhibits favorable taste quality.SOLUTION: A polished rice characterized in that substantially the entire surface of the rice grain has the aleurone layer exposed, (1) the exposed aleurone layer being the lowermost one layer or its basal part among the aleurone layer that existed as a single layer or plural layers in the rice grain before polishing, and (2) the α-amylase activity being 0.3 CU / g or higher in a 1 wt.% yield portion of the rice grain surface.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a novel milled rice. [Background technology]

[0002] Brown rice is rice seed from which the husk has been removed, and has long been used as food, feed, brewing, etc. As shown in Figure 1, the layer structure of brown rice is known to consist of, from the surface, the epidermis 21, pericarp 22, seed coat 23, aleurone cell layer 24 (hereinafter referred to as the "aleurone layer"), and subaleurone cell layer 25 (hereinafter referred to as the "subaleurone layer"), with the center consisting of endosperm (starch-storing cell layer) 26. The layers from the epidermis 21 to the aleurone layer 24 are also called the bran layer. The epidermis 21 also has a layer known as the waxy layer, which is a waxy, waterproof layer that prevents germination.

[0003] 2 shows the layer structure of the germ region of brown rice. The germ 50 present in the head H of brown rice is composed of, from the surface, a germ surface layer 52, a germ main portion 53, and a germ base portion 54 including the germ scutellum 54a. The scutellum 54a is attached to a group of broken cells 55 of the endosperm 26.

[0004] Brown rice is more nutritious than polished rice. According to the Standard Tables of Food Composition in Japan (8th Edition) Supplement 2023 (hereinafter referred to as "8th Edition"), for example, the total dietary fiber content of polished rice is 0.5g / 100g, while that of brown rice is 3.0g / 100g. Also, for example, the vitamin E content of polished rice is 0.1mg / 100g, while that of brown rice is 1.4mg / 100g.

[0005] However, despite its high nutritional value, consumers tend to avoid brown rice. The main reasons for this are that it is somewhat hard and not very palatable, and the bran remains in the mouth, making it less palatable.

[0006] In order to solve these problems related to the taste of brown rice and to develop rice that allows the effective intake of the nutrients of brown rice, the applicant of the present application has developed and already commercialized no-wash rice (Patent Document 1) in which the subaleurone layer is exposed on the surface of the rice grain. This no-wash rice not only allows the intake of the nutrients contained in the subaleurone layer, but also has a better taste than brown rice.

[0007] In this regard, the aleurone layer above the subaleurone layer is relatively rich in nutrients, just like the subaleurone layer, so if the aleurone layer could be left on the surface of the rice grain along with the subaleurone layer, it would be possible to provide rice with higher nutritional value. Several proposals have been made to leave the aleurone layer on the surface of the rice grain.

[0008] For example, instant brown rice has been proposed, which has a single grain with the aleurone layer and surrounding tissue remaining on at least a portion of the grain surface and has a bulk density of 0.10 to 0.30 g / ml (Patent Document 2).

[0009] For example, it has been proposed to produce polished rice by removing the pericarp and seed coat of brown rice using a specific polishing method, leaving part of the aleurone layer and part of the germ remaining (Patent Document 3).

[0010] Furthermore, a rice milling method is known in which untreated brown rice is heated for 2 to 10 seconds using superheated steam at normal pressure and 180°C to 250°C, causing condensation water to form on the surface of the brown rice in the initial stage of heating, and the condensation water is removed by heating the brown rice with the superheated steam; a steam separation process, immediately after the superheated steam treatment, separating the superheated steam from the brown rice; and a cooling process, immediately after the steam separation treatment, cooling the brown rice, and the brown rice is milled so as to leave the boundary portion of the aleurone layer of the brown rice that contacts the endosperm (Patent Document 4). [Prior art documents] [Patent documents]

[0011] [Patent Document 1] Patent No. 4708059 [Patent Document 2] Patent Publication No. 9-299048 [Patent Document 3] Patent Publication No. 2016-120459 [Patent Document 4] Patent No. 4746706 Summary of the Invention [Problem to be solved by the invention]

[0012] However, although these conventional techniques produce an aleurone layer on the surface of rice grains, it is difficult to say that the nutrients contained in the aleurone layer are fully utilized, and there is also room for improvement in terms of taste.

[0013] Therefore, a primary object of the present invention is to provide milled rice that is more nutritious and has a good taste. [Means for solving the problem]

[0014] The inventors of the present invention have conducted extensive research in light of these problems with the prior art and have discovered that the above-mentioned objectives can be achieved by rice having a specific layer structure in which a specific layer above (on the surface side of) the endosperm, which is the boundary between the bran layer and the endosperm in brown rice, is selectively left on the surface of the rice grain, thereby completing the present invention.

[0015] That is, the present invention relates to the following polished rice. 1. Rice in which the aleurone layer is exposed over substantially the entire surface of the grain, (1) The exposed aleurone layer is the bottom layer or the lowermost layer of the single or multiple layers of aleurone layers present in the rice grain before milling. (2) The α-amylase activity is 0.3 CU / g or more in the 1% by weight yield portion of the rice grain surface. This is a characteristic of milled rice. 2. Milled rice as described in paragraph 1 above, in which 90% or more of the rice grains have "germs with the surface portion of the germ scraped off," "scutellum, which is the basal portion of the germ that remains after the surface or protruding portion has been scraped off," or "groups of crushed cells" remaining. 3. The polished rice according to item 1, wherein the ash content is 2 g / 100 g or more in the 1% by weight yield portion of the surface of the rice grain. 4. The polished rice according to item 1, having a whiteness of 33 to 43. 5. The milled rice according to item 1, wherein the yellowness of the cooked rice when the milled rice is cooked is 15 to 22. 6. The polished rice described in item 1 above, which has a yield rate of 91% or more and 94% or less. [Effects of the Invention]

[0016] According to the present invention, it is possible to provide milled rice that has higher nutritional value and good taste.

[0017] In particular, the polished rice of the present invention has a structure in which one of the lowest layers of the aleurone layer or its lower base is exposed over substantially the entire rice grain, allowing the nutrients contained in brown rice to be ingested at a high concentration. In particular, the cell outlines (cell walls / cell membranes) of the aleurone layer or the boundary between the aleurone layer and the subaleurone layer remain, which suppresses or prevents the loss of sweet and umami components of the subaleurone layer below the aleurone layer, for example, during rice washing before cooking or during no-rinse processing, thereby maintaining high nutritional value. In other words, not only the nutrients contained in the aleurone layer but also the sweet and umami components of the nutrients in the subaleurone layer can be reliably retained, resulting in high nutritional value and good taste at the same time. Furthermore, the polished rice (or cooked rice thereof) of the present invention has a taste and appearance similar to white rice, and can be provided as a rice product that is easier to eat than brown rice or the like. [Brief explanation of the drawings]

[0018] [Figure 1] FIG. 1 is a schematic cross-sectional view showing the layer structure from the surface to the deep layer of a grain of brown rice. [Figure 2] FIG. 2 is a schematic cross-sectional view showing the layer structure of each part of the germ and the surface to the deep layer of the brown rice in the germ region of brown rice. [Figure 3]Fig. 3A is a schematic diagram showing the state in which the lowest aleurone layer remains, and Fig. 3B is a schematic diagram showing the state after a portion (surface portion) of the lowest aleurone layer has been scraped off. [Figure 4] FIG. 1 is a schematic diagram showing the state in which the lower bottom of the aleurone layer is exposed. [Figure 5] FIG. 1 is a diagram showing the names of the external parts of a rice grain. [Figure 6] 6A and 6B are conceptual diagrams illustrating the process of scraping off the aleurone layer so that it remains at a substantially uniform thickness. Fig. 6A shows the state before a portion of the aleurone layer has been scraped off. Fig. 6B shows the state after a portion of the aleurone layer has been scraped off. [Figure 7] 7(a) is a schematic diagram showing the structure of a rice polishing machine used in the present invention, and FIG. 7(b) is a cross-sectional view taken along line II of FIG. 7(a). [Figure 8] This shows the results of observation under an optical microscope using toluidine blue staining of the no-wash rice obtained in Example 1. The central figure (1) shows the results of observation of the entire rice grain (overall observation figure), and the surrounding figures (4) show the results of observation of parts of the rice grain (partial observation figure). [Figure 9] These are magnified images of brown rice stained with toluidine blue observed under an optical microscope. The central image (1) shows the results of observing the entire grain of rice, and the surrounding images (4) show the results of observing parts of the grain. [Figure 10] This is an enlarged view of the overall observation of the rinse-free rice observed in Figure 8. [Figure 11] FIG. 9 is an enlarged view of a portion of the rinse-free rice observed in FIG. 8. [Figure 12] FIG. 9 is an enlarged view of a portion of the rinse-free rice observed in FIG. 8. [Figure 13] FIG. 9 is an enlarged view of a portion of the rinse-free rice observed in FIG. 8. [Figure 14] FIG. 9 is an enlarged view of a portion of the rinse-free rice observed in FIG. 8. [Figure 15] 1 shows the results of observing the vicinity of the boundary between the endosperm and the scutellum of the germ in the wash-free rice obtained in Example 1 under an optical microscope. [Figure 16]FIG. 1 shows the results of appearance observation of the rinse-free rice obtained in Example 1 by rhodamine 6G staining. [Figure 17] FIG. 1 is a diagram showing the results of appearance observation of the rinse-free rice obtained in Example 1 by staining with Prussian blue. [Figure 18] FIG. 1 is a schematic diagram showing the shape of protrusions formed on the polishing tube of a rice polishing machine used in the production of milled rice of the present invention. [Figure 19] FIG. 1 is a schematic diagram showing the shape of protrusions formed on the polishing tube of a rice polishing machine used in the production of milled rice of the present invention. [Figure 20] This is a partially enlarged image (700x) of brown rice stained with toluidine blue and observed under an optical microscope. [Figure 21] This is a partially enlarged observation image (700x) of another part of the unwashed rice observed in Figure 8. DETAILED DESCRIPTION OF THE INVENTION

[0019] 1. Milled rice of the present invention The polished rice of the present invention (polished rice of the present invention) is rice in which the aleurone layer is exposed over substantially the entire surface of the rice grain, (1) The exposed aleurone layer is the bottom layer or the lowermost layer of the single or multiple layers of aleurone layers present in the rice grain before milling. (2) α-amylase activity of 0.3 CU / g or more in the 1% by weight yield portion of the surface of the rice grain; It is characterized by:

[0020] (1) Structure of the milled rice of the present invention In the polished rice of the present invention, the aleurone layer is exposed over substantially the entire surface of the rice grain. That is, as shown in Figure 1, the layer structure of ordinary brown rice is, from the surface layer (outermost layer), epidermis 21 (waxy layer), pericarp 22, seed coat 23, aleurone layer 24, and subaleurone layer 25, and the underlying central part of the rice grain is composed of endosperm (starch-storing cell layer) 26. However, in the polished rice of the present invention, at least the epidermis 21, pericarp 22, and seed coat 23 have been almost completely removed from the brown rice.

[0021] Here, the term "substantially" means that within a single grain of milled rice of the present invention, there may be unavoidable portions where part of the aleurone layer covering the surface is missing (i.e., portions where the underlying sub-aleurone layer, etc., is exposed), as long as the effects of the present invention are not impaired. For example, some brown rice grains have a condition known as "skin rubbing," which occurs mainly during harvesting or during the drying and hulling processes after harvesting, and refers to a state in which the surface of the brown rice grains is damaged. Other examples include cases where the aleurone layer is congenitally missing, or where the aleurone layer has been partially scraped off artificially or accidentally during the manufacturing process.

[0022] The exposed aleurone layer in the polished rice of the present invention is the lowest layer or its lower bottom portion of the single or multiple aleurone layers present in the rice grain before polishing. Generally, the aleurone layer in brown rice is present in parts of the rice grain that are a single layer (single layer) and parts that are multiple layers of two or more layers, depending on the part of the rice grain. In the polished rice of the present invention, the aleurone layer is scraped from the surface side, leaving the lowest layer or its lower bottom portion of the aleurone layer. This lowest layer of the aleurone layer is in contact with the subaleurone layer.

[0023] One layer of the aleurone layer is a layer formed by arranging each cell constituting the individual aleurone layers in a horizontal row. The lower base is a layer from which a portion (particularly the upper portion) of each cell constituting that layer (the bottom layer) has been removed. For example, FIG. 3A shows a schematic diagram of one layer of the aleurone layer. The lowermost layer 24a of the aleurone layer remains, with each cell A arranged in a horizontal row. In FIG. 3B, the upper portion R of each cell A has been removed, but a portion of the cell remains, forming the lower base 24a'. The remaining portion of the lower base 24a' is not particularly limited as long as it does not impede the effects of the present invention, but is usually the cytoplasm, cell membrane, cell wall, etc. of the aleurone layer. In particular, in the present invention, from the viewpoint of effectively suppressing or preventing the outflow of sweet and umami components from the subaleurone layer, it is preferable that (a) the outline portions (cell walls and cell membranes) of the cells of the aleurone layer and / or (b) the boundary portion between the aleurone layer and the subaleurone layer remain as the lower base. The presence of such a lower base 24a' can be confirmed by observing the thickened portion of the rice grain outline (outermost portion) among the four sides of the approximately square cell, as shown in FIG. 4, for example.

[0024] In this way, the milled rice of the present invention has the aleurone layer, which is the softest in the rice grain structure, present on the surface of the rice grain in a nearly uniform thickness. By adopting this structure, it is possible to obtain a higher concentration of nutrients and provide milled rice with a good taste, as will be described later. In other words, by adopting a structure in which the surface of the milled rice is covered with the lowest layer or the lower bottom part of the aleurone layer in a nearly uniform thickness, it is possible to provide cooked rice that swells and becomes whiter than conventional partially milled rice during cooking, is delicious, and contains a higher concentration of brown rice components than the golden germ rice described below.

[0025] The structure in which the surface of milled rice is covered with the lowest layer or the bottom portion of the aleurone layer in a substantially uniform thickness can be confirmed by staining the milled rice with toluidine blue and observing it with an optical microscope, for example, as shown in the Examples below. Figure 5 shows a schematic diagram of the appearance of a rice grain. Figure 5A is a view of the rice grain viewed with the ventral side facing forward. Figure 5B is a view of the rice grain viewed with the ventral side facing side. For example, after observing the entire rice grain, the thickness and cells of the aleurone layer can be examined at four points, for example, the central part of the ventral side, the central part of the dorsal side, and the two boundary areas between the ventral and dorsal sides, as shown in the area surrounded by the dotted circle a in Figure 5. The layer structure of the aleurone layer at each observation point can be compared with the layer structure of brown rice, thereby identifying the above structure.

[0026] Although toluidine blue was used as the staining solution in the examples, any solution that allows observation of the lowest layer or bottom portion of the aleurone layer is not particularly limited, as long as it allows observation of the lowest layer or bottom portion of the aleurone layer. For example, the cell outlines (cell walls and cell membranes) of the aleurone layer or the boundary between the aleurone layer and the subaleurone layer have a certain thickness, and the presence or absence of the remaining outlines or boundaries can be confirmed using toluidine blue, which can stain polysaccharides such as cell walls. Other examples that can be used include methylene blue or safranin, which stain cell walls, and Sudan IV, which stains lipids. These can be used alone or in combination of two or more.

[0027] The term "milled rice" as used herein includes, for example, what is called "wash-free rice," "germ-milled rice," and "partially milled rice," as long as it does not interfere with the effects of the present invention. In contrast, milled rice that does not meet the requirements of the present invention, particularly milled rice from which the aleurone layer has been completely removed, is excluded. Therefore, for example, milled rice in which the subaleurone layer and / or endosperm (starch-storing cell layer) is exposed over the entire surface of the rice grain, is excluded from the present invention.

[0028] Furthermore, it is desirable that the polished rice of the present invention has a remaining "germ with the surface portion of the germ scraped away," or a "scutellum, which is the basal portion of the germ (which has an unpleasant texture) after the surface or protruding portion has been scraped away," or a "group of crushed cells" in 90% or more of the rice grains by number. In the present invention, the above number percentage means that, for example, when observing 100 randomly selected rice grains, 90 or more grains have one of the above three portions.

[0029] The crushed cells are an accumulation of powdery material present at the bottom of the base of the germ (the scutellum) (at the boundary between the endosperm and the germ scutellum). In conventional technology, the crushed cells are removed when the germ scutellum falls off, whereas in the present invention, the crushed cells can be left in the rice grain even if the germ scutellum is removed. The crushed cells, especially along with the germ scutellum, are rich in iron, so by effectively retaining them, it is possible to provide milled rice with higher nutritional value.

[0030] The whiteness of the milled rice of the present invention is preferably in the range of 33 to 43, and particularly preferably 38 to 43 (for example, milled rice that has been processed to remove the bran adhering to the surface of the rice grains). The whiteness of ordinary white rice is about 45 to 50, so although the milled rice of the present invention appears slightly yellowish compared to white rice when observed with the naked eye, when the milled rice of the present invention is observed alone it appears to have an appearance similar to white rice.

[0031] Furthermore, when the polished rice of the present invention is cooked, it is preferable that the yellowness index is 15 to 22. Since the yellowness index of ordinary cooked rice made with germ rice is 22 or more, the cooked rice looks the same as or whiter than cooked rice made with germ rice.

[0032] The retention rate of the polished rice of the present invention is not limited, but is preferably about 91 to 94% by weight. This makes it possible to more efficiently provide rice grains in which the aleurone layer remains at a substantially uniform thickness. Therefore, it is possible to set the retention rate at, for example, 91.5 to 93.5% by weight.

[0033] (2) Components contained in the milled rice of the present invention The polished rice of the present invention is characterized by an α-amylase activity of 0.3 CU / g or more in a 1% weight yield portion of the rice grain surface. In this invention, "1% weight yield portion of the rice grain surface" refers to 1% weight of the surface of the polished rice of the present invention obtained by uniformly polishing the surface (the same applies hereinafter). The upper limit of α-amylase activity varies depending on, for example, the brown rice used, and can be, for example, about 0.4 CU / g or about 0.6 CU / g, but is not limited to this.

[0034] α-Amylase is a saccharifying enzyme (a component that can break down starch into sugar) and is a type of enzyme found in rice. Its action is to produce sugar during the soaking process of rice cooking. This sugar is released during cooking, but as the water evaporates during cooking, it reattaches to the surface of the rice grain as reducing sugars, contributing to the sweetness of the rice surface (the sweet taste when eaten), its luster, or the so-called "stickiness" (a viscous film that forms on the surface of cooked rice, which is the true essence of rice's deliciousness and improves its texture). Therefore, a high level of α-amylase on the surface of rice grains is an indicator of the ability to provide rice that is more delicious and smoother to the touch.

[0035] The applicant has already developed and marketed highly nutritious rice products, including no-wash rice with the subaleurone layer remaining on the surface of the grain (hereinafter referred to as "kinmemai"; "kinmemai" is a registered trademark) (Patent No. 4708059), and rice with the wax layer removed (excluding rice with the pericarp completely removed) (hereinafter referred to as "wax-cut brown rice"; "wax-cut brown rice" is a registered trademark) (Patent No. 6850526). The polished rice of the present invention surpasses these earlier products in both high nutritional value and good taste. In fact, a comparison of the α-amylase activity in the 1% weight percent retention portion of the surface of the rice grain for the present invention, kinmemai, and wax-cut brown rice yields the results shown in Table 1. Table 1 also shows the values ​​for commercially available polished rice.

[0036] [Table 1]

[0037] As shown in Table 1, wax-cut brown rice in particular has the entire aleurone layer remaining intact, but the pericarp and seed coat remain on the surface of the rice grain. For this reason, it can be seen that the milled rice of the present invention, in which the lowest layer of the aleurone layer or the bottom layer thereof remains, has higher α-amylase activity on the surface of the rice grain.

[0038] Furthermore, the polished rice of the present invention preferably contains an ash content of 2 g / 100 g or more in a 1% weight yield portion of the surface of the rice grain. Ash content is an indicator of mineral content. The upper limit of ash content varies depending on, for example, the brown rice used, and can be, for example, about 3 g / 100 g, or about 4 g / 100 g, or even about 5 g / 100 g, but is not limited to these. Table 2 shows the results of a comparison of ash content with golden germ rice and other varieties.

[0039] [Table 2]

[0040] As shown in Table 2, in terms of ash content, the milled rice of the present invention is found to be richer in minerals than highly nutritious rinse-free rice such as golden germ rice.

[0041] Furthermore, the polished rice of the present invention is relatively rich in γ-oryzanol, ferulic acid, and phytic acid, which are found in large amounts in brown rice (especially the bran portion). More specifically, the γ-oryzanol content is usually 3 mg / 100 g or more, preferably 3.5 mg / 100 g or more, and more preferably 4 mg / 100 g or more. The total ferulic acid content is usually 10 mg / 100 g or more, preferably 12 mg / 100 g or more, and more preferably 13 mg / 100 g or more. The phytic acid content is usually 90 mg / 100 g or more, preferably 120 mg / 100 g or more, and more preferably 140 mg / 100 g or more. The contents of these components are compared with those of golden germ rice and other varieties, as shown in Table 3.

[0042] [Table 3]

[0043] As shown in Table 3, the polished rice of the present invention has a lower nutritional content than wax-cut brown rice and golden germ rice, but retains a higher concentration of the nutritional components of brown rice than golden germ rice.

[0044] The polished rice of the present invention can be used to obtain cooked rice in the same manner as ordinary rice (commercially available products). Therefore, for example, the same conditions as for commercially available products can be used for soaking, which is a pre-cooking step. If the polished rice of the present invention is no-wash rice, the rice washing step before cooking can be omitted. Furthermore, there are no limitations on the equipment used for cooking the rice, and it can be cooked using, for example, a commercially available rice cooker.

[0045] 2. Method for producing polished rice of the present invention The method for producing polished rice of the present invention basically employs a method that includes a step of polishing brown rice so that the aleurone layer remains at a substantially uniform thickness. For example, the following production method can be suitably employed.

[0046] A method for producing milled rice in which the aleurone layer is exposed over substantially the entire surface of the rice grain, comprising: The rice milling machine uses a milling chamber, which is a space between a milling cylinder having a rice inlet and a rice outlet and no wart-like or linear protrusions on the inner surface, and a milling roll disposed inside the milling cylinder and having ridges and rice-feeding spirals on the outer surface, where brown rice grains rub against each other to mill the rice. The method includes a step of applying an appropriate pressure to the discharged brown rice grains by a pressing means provided at the discharge port while increasing the rotation speed of the polishing roll, agitating the brown rice grains continuously flowing into the polishing chamber from the rice supply port with the action of the polishing roll rotating at high speed at an appropriate degree of filling, and discharging the rice grains from the discharge port after peeling the surface layer of each brown rice grain very thinly over the entire surface. By using the above-mentioned production method, the polished rice of the present invention can be produced more reliably.

[0047] In the manufacturing method of the present invention, brown rice is used as the starting material. As mentioned above, the number of aleurone layers in brown rice varies depending on the part of the rice grain. Figure 5 shows the ventral and dorsal parts of a rice grain. Figure 5A is a front view of the ventral side. Figure 5B is a side view of the ventral side. Generally, there are one to two layers on the ventral side of a rice grain, while there are four to five layers on the dorsal side. For this reason, if brown rice is peeled evenly from the surface, even if the dorsal aleurone layer can be peeled to some extent, the ventral aleurone layer will be completely lost. On the other hand, if an attempt is made to maintain the ventral aleurone layer, the dorsal aleurone layer will be barely peeled at all.

[0048] Therefore, in the present invention, a method is adopted in which less aleurone layers are scraped off from areas with fewer layers and more aleurone layers are scraped off from areas with more layers, thereby achieving uneven peeling.

[0049] For example, Figure 6 shows an image of scraping off the aleurone layer so that it remains at a substantially uniform thickness. In reality, the aleurone layer is formed on the surface of the rice grain and therefore has a curved surface, but for convenience, it is depicted as a flat surface in Figure 6. Furthermore, in Figure 6, the layers above the aleurone layer are not shown. As shown in Figure 6A, before milling, aleurone layers 24, each with a different number of layers, are stacked on top of sub-aleurone layers 25.

[0050] After milling by the method of the present invention, only the bottom layer 24a of the aleurone layer remains, as shown in Figure 6B. That is, in the manufacturing method of the present invention, in the multi-layer portion (portion A) consisting of four single layers 24a, 24b, 24c, and 24d of the aleurone layer present in Figure 6A, three layers (single layers 24b, 24c, and 24d) are scraped off. On the other hand, in the multi-layer portion (portion B) consisting of two single layers 24a and 24b, only single layer 24b is scraped off. In other words, the thickness of the aleurone layer scraped off varies depending on the region of the aleurone layer. As a result, the thickness of the remaining aleurone layer 24a is approximately uniform in every portion.

[0051] As described above, the basic technology of the manufacturing method of the present invention is a new equal-pressure rice-milling technology that makes the "thickness of the part that is left behind" uniform, as opposed to the wax-cut brown rice-milling technology that makes the "thickness of the part that is scraped off" uniform. By peeling while controlling the number of aleurone layers that exist in different parts of the brown rice grain (i.e., by controlling the thickness of the aleurone layers that remain after scraping off), it is possible to provide the milled rice of the present invention with the unique structure described above.

[0052] Furthermore, the basic technology of the manufacturing method of the present invention utilizes the "differences in the properties of the layers constituting brown rice grains." Unlike the golden germ rice milling technique, which leaves the subaleurone layer on the surface of the rice grain, this new equal-pressure milling technique leaves identical layers with identical properties uniformly. The difference between the aleurone layer, the subaleurone layer, and the endosperm is whether or not they contain starch, which has rock-hard properties. While the subaleurone layer and endosperm contain starch to varying degrees, conventional golden germ rice milling techniques utilize the difference in properties between the aleurone layer, which does not contain starch and is very soft, and mill the rice with a force that allows the aleurone layer to be peeled but not the subaleurone layer. Even if the subaleurone layer is partially exposed on the surface of the rice grain early in the milling process, the subaleurone layer remains and is not removed thereafter. The aleurone layer is gradually removed over the entire surface of the rice grain, exposing the subaleurone layer. In contrast, the manufacturing method of the present invention can be said to be a technique for peeling the aleurone layer, which is an identical layer with identical properties, while controlling the thickness of the aleurone layer.

[0053] One of the important features of the production of the milled rice of the present invention is that, in particular, the entire surface of the brown rice grain is shaved extremely thinly, and uneven peeling is avoided, of course, but the rice grains are also rotated around their long axes while maintaining a constant level of rice grain density in the milling chamber without erratic rotation. This ensures that the long parts of the rice grain are not shaved more first, and that the thick part, or the shortest axis, is shaved evenly. The outer layer of the aleurone layer, which is the softer layer, is shaved first. Even if the number of layers of aleurone layer stacked varies depending on the part of the brown rice grain, the aleurone layer can remain at approximately the same thickness on all parts of the milled rice surface. As long as this process can be achieved, the milled rice of the present invention can be produced by various means and devices. Therefore, for example, existing or commercially available rice mills or polishers may be modified as appropriate and used.

[0054] As described above, in the manufacturing method of the present invention, a rice milling machine can be suitably used in which rice is milled by friction between brown rice grains in a milling chamber, which is the space between a milling cylinder that has a rice inlet and a discharge outlet and has no wart-like or linear protrusions (resistance-type protrusions) on its inner surface and a milling roll that is disposed inside the milling cylinder and has ridges and rice-feeding spirals on its outer surface.

[0055] A schematic diagram of this rice milling machine is shown in Figure 7. The rice milling machine shown in Figure 7(a) is basically comprised of a polishing tube 1 with a rice inlet 6, a polishing roll 3 arranged inside the polishing tube, and a pressure plate 8 arranged on the tip end of the polishing roll in an extension line. A rice feed spiral 5 is formed on the side surface of the polishing roll 3 in an area below the rice inlet 6. Furthermore, as shown in Figure 7(b), two ridges 4, 4' are formed on the side surface of the polishing roll 3 at the tip end. The polishing tube 1 is made of a mesh-like body, and its side surface is formed with meshes (through holes) 2', 2'', 2''', ... The polished rice grains are removed from a discharge opening 7 at the tip of the polishing tube 1. In particular, in the above-mentioned device, protrusions p are formed on the inner surface of the polishing tube 1 to facilitate rotation of the rice grains.

[0056] In particular, the device used in the present invention is characterized by the use of (1) a polishing tube that does not have the wart-like or linear protrusions (resistance-type protrusions) that are provided on the inner surface of the polishing tube of a conventional rice polisher to hook and immobilize rice grains, thereby increasing resistance and thereby increasing the polishing pressure (bran removal effect), or (2) a polishing tube that, instead of the resistance-type protrusions, has protrusions on the inner surface that facilitate the rotation of rice grains (non-resistance-type protrusions: the protrusions of the present invention). The preferred method is to use a polishing tube of type (2). That is, this method provides protrusions that facilitate the rotation and agitation of rice grains, rather than the function of hooking and immobilizing rice grains. This prevents rice grains from remaining in the polishing tube for long periods of time, thereby reducing the pressure on the rice grains and enabling the desired polishing to be performed efficiently. In other words, by forming protrusions that can promote the sliding movement of rice grains when viewed from a longitudinal cross section of the polishing cylinder, and that can promote the movement of rice grains so that they approach the polishing rolls when viewed from a cross section perpendicular to the longitudinal direction of the polishing cylinder, the polished rice of the present invention can be obtained more reliably.

[0057] A specific example of such a protrusion of the present invention is shown in Figure 18. Figure 18A is a view of cross section II of the polishing cylinder in Figure 7 (a cross section seen from the bottom side of the polishing cylinder). Figure 18B is a cross section of the polishing cylinder seen from the side. The polishing rolls are not shown in these drawings. In this case, the protrusions p of the present invention are shaped or arranged to move rice grains moving around the polishing roll in a direction (arrow A) that brings them closer to the polishing roll in the cross section of Figure 18A. In the cross section of Figure 18B, the protrusions are shaped or arranged to slide rice grains coming down from above downward (arrow B) in the direction of travel (the direction in which the rice grains move to be discharged from the rice mill).

[0058] Here, the "shape" in the above "shape or arrangement" refers to a protrusion shape that can direct rice grains in the direction of arrow A or arrow B with just one protrusion. Also, the "arrangement" in the above "shape or arrangement" refers to an installation form that can direct rice grains in the direction of arrow A or arrow B with multiple protrusions.

[0059] The above-mentioned shapes are not limited, and the three-dimensional shape of the projections p of the present invention is not particularly limited, and examples thereof include a substantially rectangular parallelepiped (substantially plate-like), a substantially cube, a substantially cylindrical, a substantially conical, a substantially triangular pyramid, a substantially square pyramid, a substantially truncated cone (frustum cone), and a substantially truncated pyramid. For example, as shown in Figure 18A, when viewed from a cross section perpendicular to the longitudinal direction of the polishing roll, the projections p may have a shape that makes rice grains climb uphill. Furthermore, as shown in Figure 18B, when viewed from a cross section in the longitudinal direction of the polishing roll, the projections p may have a shape that makes rice grains falling from above slide down in the direction of travel.

[0060] Furthermore, conventional rice milling machines have protrusions, as shown by the dotted lines in Figure 18B, which increase the pressure caused by friction between the brown rice grains and push the rice grains back to efficiently peel off more of the bran layer, thereby increasing the pressure inside the milling cylinder. This makes it easier for the rice grains to remain in the rice milling machine for a relatively long time, and all of the aleurone layer is scraped off. Therefore, it is difficult to obtain the milled rice of the present invention using conventional rice milling machines.

[0061] The above arrangement is not limited, and multiple protrusions can be appropriately arranged so as to move the rice grains in the direction of arrow A or arrow B. For example, in FIG. 19A, an arrangement of three protrusions p1 to p3 is configured to move the rice grains in the direction of arrow A. In FIG. 19B, an arrangement of four protrusions p1 to p4 is configured to more effectively move the rice grains in the direction of arrow B.

[0062] In Figure 18, one protrusion p has both the function of moving rice grains in the direction of arrow A (function A) and the function of moving rice grains in the direction of arrow B (function B), but any protrusion that has at least one of function A and function B will suffice. In particular, in the present invention, a protrusion that combines both function A and function B is desirable. This makes it possible to more effectively impart the effect of making it easier for rice grains to rotate and stir with a smaller number of protrusions.

[0063] The size of the protrusions of the present invention is not limited, but can be set appropriately within the range of, for example, a length (perpendicular to the rice polisher) of 5 to 10 mm, a width (horizontal to the rice polisher) of 50 to the length of the polishing cylinder mm, and a height of 1 to 2 mm.

[0064] The number of protrusions of the present invention can be appropriately set depending on the size of the rice grains, the size and length of the polishing cylinder, etc., but for example, 1 protrusion per 5 cm 2 In the case of a line, it may be installed horizontally to the rice milling machine, but it is preferable to tilt it at an angle that does not oppose the rotation direction of the rice milling rolls (the angle direction in which the rice is sent out).

[0065] Furthermore, the apparatus used in the present invention is configured to increase the rotation speed of the rotating roll (whitening roll), reduce the workload of the rotating roll per rotation, and apply only slight pressure to the rice grains in the whitening chamber (the space between the whitening cylinder and the rotating roll) during operation, thereby maintaining a constant degree of filling. Specifically, the workload of the rotating roll per rotation is approximately 3 A (amperes) per horsepower (0.75 kW) of an electric motor (three-phase 200 V (volts)) for normal white rice, whereas in the present invention it can be set to approximately 1.8 A to 2.3 A, but is not limited to this. In this way, by adopting relatively mild conditions, a constant degree of filling can be maintained and the degree of removal of the aleurone layer of the rice grains can be controlled, resulting in the aleurone layer remaining at a nearly uniform thickness.

[0066] By using a rice milling machine having the protrusions of the present invention as described above and milling to a yield range of approximately 91 to 94%, rice grains in which the aleurone layer remains at a nearly uniform thickness can be obtained more efficiently.

[0067] The obtained rice grains have a small amount of skin bran attached to the surface of the rice grain, sticking to the rice skin. Skin bran is easily oxidized when exposed to air, which leads to a deterioration in taste, so it is desirable to remove the skin bran. Therefore, the obtained rice grains can be further placed in a no-wash rice machine to remove the skin bran attached to the surface of the rice grains, thereby obtaining no-wash rice, which is one type of milled rice of the present invention.

[0068] The no-wash rice machine is not limited as long as it can remove rice bran, and may be, for example, one disclosed in JP 2-242647 A and JP 2004-321001 A, which are inventions of the present inventors. Alternatively, commercially available no-wash rice machines can be used. The removal of rice bran can be confirmed by measuring the turbidity in accordance with the Japan Industrial Standards (JIS K0101 Industrial Water Testing Method) in accordance with the National No-Wash Rice Association method and determining whether it is below the standard value. Turbidity is expressed in "ppm," which corresponds to "mg / L" or "degrees" in the Japan Industrial Standards (JIS K0101).

[0069] In the polished rice or no-wash rice produced in this way, the exposed aleurone layer is the single or multiple layer of aleurone present in the rice grain before polishing, and the bottom layer or the lower part of that layer remains. At the same time, because this polished rice (especially no-wash rice) is produced by the special method described above, it is possible to leave the crushed cell group in the rice grain even if the scutellum of the germ has been removed. [Example]

[0070] The features of the present invention will be described in more detail below with reference to examples and comparative examples, but the scope of the present invention is not limited to these examples.

[0071] [Example 1] 30 kg of brown rice (Koshihikari produced in Nagano Prefecture in 2022) was polished using the following rice polishing machine to produce polished rice (wash-free rice). The rice mill used was a modified MC-2 rice mill manufactured by Toyo Rice Co., Ltd. The width of the numerous rectangular meshes 2, 2', 2"... on the polishing cylinder 1 of the rice polishing machine shown in Figure 7(a) is narrowed to 0.7 mm to make it less likely that rice grains moving in contact with the cylinder 1 will get caught in the meshes 2, 2', 2"... and slight linear protrusions p with a tapered shape and a height of 1 mm are provided. Furthermore, the rotation speed of the polishing roll 3 is increased to 1,500 rpm. To enable the rice grains to be discharged from the polishing chamber between the polishing cylinder 1 and the polishing roll 3 without applying excessive pressure to the mass of rice grains inside, the two ridges 4, 4' on the outer surface of the polishing roll 3 are twisted at an angle of approximately 27 degrees from the tip of the rice feed screw 5 to the central part 3' of the polishing roll 3, as shown in Figure 7(a), in the same twist direction as the rice feed screw 5, and from the central part 3' to the tip 3" of the polishing roll 3, the twist angle is set to approximately 0 degrees, so that the rice grains are aligned horizontally (longitudinal direction).

[0072] The operation of the rice milling machine modified as described above is that after foreign objects and grains of different colors have been sorted and removed using a stone remover, color sorter, etc. (neither of which are shown), a group of brown rice grains falls from the rice inlet 6 of the rice milling machine and is transported to the left in Figure 7(a) by the rice feed spiral 5, which is rotating at high speed, until it approaches the polishing roll 3. Here, from the tip of the rice feed spiral 5 to the center 3' of the polishing roll 3, two ridges 4, 4' formed integrally with the polishing roll 3 have a twist angle of 27 degrees. Therefore, the brown rice grains are agitated by these two ridges 4, 4', and the rice grains are aligned horizontally (in the longitudinal direction) by the tapered linear projections p of the polishing cylinder 1, which are 1 mm high. The rice grains are then discharged from the discharge outlet 7 with almost no load due to the transport action of the rice feed spiral 5 and the ridges 4, 4' at the rear part of the polishing roll 3, which are twisted in the same direction as the rice feed spiral 5, although they are somewhat straight.

[0073] However, this alone does not change the brown rice grains, so an appropriate pressure is applied to the group of brown rice grains by operating the adjustment screw 9 with the pressure plate 8. As a result, the brown rice grains that continuously flow into the milling chamber from the rice supply port 6 are discharged from the discharge port 7 while resisting the pressure of the pressure plate 8, while maintaining a constant, moderate level of fullness. Meanwhile, the brown rice grains sent from the rice delivery spiral 5 are stirred by the action of the milling roll 3, which rotates at a speed of 1,500 rpm, as they move from right to left in the milling chamber, at a constant, moderate level of fullness, as shown in Figure 7(a). At this time, because the mesh 2, 2', 2''... of the peripheral surface of the polishing cylinder 1 is extremely thin, with a width of about 0.7 mm, the brown rice grains hardly get caught in the mesh 2, 2', 2''... Instead, the rice grains are aligned horizontally (in the direction of their long axis) by small, tapered, linear protrusions p with a height of 1 mm as shown in Figure 7(b), and the rice grains rotate around their long axis as they pass through the polishing chamber while being agitated at high speed.

[0074] According to this embodiment, compared to conventional rice milling machines, (1) the pressure is not high but just right, (2) the rice grains in contact with the inside of the milling can rotate sufficiently, rotating around their long axes, and (3) the frequency and points at which rice grains rub against each other are significantly higher. As a result, the surface layer of each brown rice grain is peeled off so that an extremely thin layer remains evenly over the entire surface, and the long part of the rice grain is not shaved off more first than the other part. The thick part, which is the shortest axis, is also shaved off evenly. The outer layer of the aleurone layer, which is the softer layer, is shaved off first. Even though the number of layers of aleurone layer stacked on top of each other varies depending on the part of the brown rice grain, the aleurone layer remains at approximately the same thickness on all parts of the surface of the milled rice. The bran generated during this process is released to the outside of the milling can through the mesh groups 2, 2', 2''... of the milling can 1, and the rice grains discharged from the discharge outlet 7 are milled rice with less than one layer of aleurone remaining.

[0075] After the rice was polished using the rice polisher, the resulting rice was further processed in a rice-polishing machine to produce the desired rice. The resulting rice was then evaluated in the following test examples.

[0076] Here, the yield of the rinse-free rice in this example was 92.1% by weight when compared with the raw material brown rice in terms of thousand kernel weight (weight of 1,000 refined kernels). The whiteness of the rice was measured using a brown rice and polished rice whiteness meter (C-600, Kett Electrical Research Institute Co., Ltd.), and the average value of three measurements was 36.6 for the polished rice and 41.5 for the no-wash rice. The yellowness of the cooked rice was measured using a spectrophotometer / colorimeter (SE7700, Nippon Denshoku Industries Co., Ltd.), and the average value of three measurements was 16.2. The cooked rice was obtained using a rice cooker (RC-MF15, Iris Ohyama Co., Ltd.), with water added according to the 1-go (1-cup) scale line on the rice cooker per one level cup of the attached measuring cup, and cooked on the normal mode (not the quick-cook mode).

[0077] [Test Example 1] The layer structure of the rice grains of the wash-free rice obtained in Example 1 was observed and the components were analyzed. More specifically, the following was carried out.

[0078] (1) Observation of the structure of rice grain surfaces The resulting no-wash rice and its raw material, brown rice, were cut at both ends of the rice grains using a simple slicer (Kenis Co., Ltd.). The cutting method used was manual sectioning. Any method that does not change the state of the rice grain surface (the outline on the cut surface) or cause collapse or deformation can be used. For example, the method is not limited to manual sectioning; other methods can be used, such as fixing rice grains to a plate that can hold the grains, soaking them in distilled water (DW) overnight at room temperature, cutting the softened grains horizontally on the plate surface, and staining the cut surface after it has been created. Next, the cut surface was stained with 0.05% toluidine blue solution (pH 7.0) (Fujifilm Wako Pure Chemical Industries, Ltd. 206-14555) for 1 minute, toluidine blue staining was performed, and then washed with distilled water (DW). The stained rice grains were observed under an optical microscope. Figure 8 shows the results of observation of the entire unwashed rice. For comparison, Figure 9 shows the results of similar observation of brown rice. Figure 10 shows an enlarged view of the center of Figure 8. Furthermore, Figures 11 to 14 each show an enlarged view (150x magnification) of the portion of Figure 10 corresponding to the dotted circle a in Figure 5. 11 to 14, it can be seen that two membranes exist on the outside of the cell wall. Taking into account the results of observing these layer structures and comparing them with the layer structure of brown rice, it can be determined that these two membranes have an aleurone layer on the outermost surface, and a subaleurone layer that remains almost evenly underneath. Therefore, it can be seen that one aleurone layer remains on the outermost surface (the outline of the cut surface) of the no-wash rice obtained in Example 1, and a subaleurone layer exists underneath. To be sure, we also examined and compared the brown rice stained with toluidine blue and the previously described no-wash rice stained with toluidine blue under an optical microscope (700x magnification) for more detailed observation. The results (optical microscope photographs) are shown in Figures 20 and 21. As is clear from these photographs (arrowed areas), in the brown rice grain shown in Figure 20, the thick cell wall of the aleurone layer, which has undergone secondary thickening and is a known characteristic of the aleurone layer, is confirmed to surround each aleurone layer cell, as indicated by the arrow. In the previously described no-wash rice stained with toluidine blue shown in Figure 21, the thick aleurone cell wall in the area adjacent to the subaleurone layer inside the aleurone layer and a portion of the thick aleurone cell wall surrounding the surrounding aleurone layer cells remain, as indicated by the arrow. It can also be confirmed that the outermost surface of the rice grain clearly shows the presence of one or more layers of the aleurone layer, particularly the outlines (cell walls and cell membranes) of the aleurone layer after the interior of the cell has been removed.

[0079] (2) Observation of the disrupted cell population The rice grains were observed under an optical microscope. The results are shown in Figure 15. The upper part of Figure 15 shows the observation results of the wash-free rice of the present invention. The lower part of Figure 15 shows the comparative observation results of the wash-free rice of the present invention (left) and rice in which the subaleurone layer is exposed over the entire surface of the grain (right). As can be seen from Figure 15, in the wash-free rice of the present invention, a cloudy area is clearly observed near the boundary between the endosperm and the germ's scutellum. This result indicates that in wash-free rice, a group of crushed cells is present in most of the bottom of the base of the germ of the rice grain. For example, the literature "Rice Science Complete Works, Volume 2, Physiology" describes crushed cell groups and indicates the location of the crushed cells at the interface between the germ tissue (germ) and the endosperm starch portion (starch-storing cell layer). Furthermore, the literature "Rice Science Complete Works, Volume 2, Morphology" indicates that the endosperm cells in the area in contact with the scutellum are in a collapsed (spongy) state. Therefore, the cloudy area near the boundary between the endosperm and the germ's scutellum is recognized as a group of crushed cells.

[0080] (3) Confirmation of the aleurone layer by staining The surface of rinse-free rice grains was stained with rhodamine 6G, and the degree of discoloration was visually observed. The results are shown in Figure 16. Rice grains with the aleurone layer remaining on the surface were darker in color than rice grains with the subaleurone layer remaining on the surface.

[0081] (4) Observation of iron content on the surface of rice grains and in crushed cell groups The surface of rinse-free rice grains was stained with Prussian blue, and the degree of discoloration was visually observed. Specifically, the grains were stained with a staining solution consisting of equal parts 2% hydrochloric acid and 2% potassium ferrocyanide. The results are shown in Figure 17. Rice grains with the aleurone layer remaining on the surface were darker in color than rice grains with the subaleurone layer remaining on the surface. In particular, rice grains containing the broken cell group and scutellum were stained a deep blue-green, as both the broken cell group and the scutellum contained a high iron content.

[0082] [Test Example 2] The components of the rice grains of the rinse-free rice obtained in Example 1 were analyzed.

[0083] (1) α-amylase activity The surface of the rinse-free rice was uniformly scraped off by 1% by weight and used as a sample. As a result, the α-amylase activity of the rinse-free rice of Example 1 was 0.32 CU / g. α-Amylase activity was measured using the Megazyme "α-Amylase Assay Kit (Ceralpha Method)" (catalog number K-CERA). Specifically, 19 mL of extraction buffer (Buffer A) was added to 1 g of sample, stirred (room temperature for 20 minutes), and then filtered through Whatman GF / A glass fiber filter paper to obtain the extract. 0.2 mL of the extract, preheated at 40°C for 5 minutes, was added to 0.2 mL of substrate-blocked paranitrophenyl maltoheptaoside (BPNPG7), preheated at 40°C for 5 minutes. After incubation at 40°C for 20 minutes, 3.0 mL of stop solution was added, stirred, and the absorbance at 400 nm was measured. α-Amylase activity was calculated using the following formula (1), which substitutes all values ​​except absorbance into the formula provided in the "α-Amylase Assay Kit (Ceralpha Method)" instruction manual. The blank absorbance was measured by adding 0.2 ml of extraction buffer (Buffer A) instead of the substrate block paranitrophenyl maltoheptaoside (BPNPG7). α-Amylase activity (CU / g) = (sample absorbance - blank absorbance) × 0.94 (1)

[0084] (2) Ash content The surface of the rinse-free rice was uniformly scraped off by 1% by weight and used as a sample. As a result, the ash content of the rinse-free rice of Example 1 was 2.6 g / 100 g. The ash content was measured by the Japan Food Analysis Center, a general incorporated foundation, using the direct ashing method.

[0085] [Test Example 3] The taste of the resulting rinse-free rice was investigated. Table 4 shows the results of comparing the taste with that of golden germ rice. The taste was measured using a commercially available multi-taste meter "MA-90SYSTEM" (model: MA-90R2, manufactured by Toyo Rice Co., Ltd.). The "Ajido Meter" uses electromagnetic waves to measure the thickness of the "water-retaining film," calculating a taste evaluation value out of 100 points, which is called "Ajido." The water-retaining film is a sticky, almost transparent, semi-cloudy substance that covers the surface of rice grains when cooked, and this is thought to be related to deliciousness. There are reports that the "Ajido Meter's" measurement value, "Ajido," shows a high correlation with the taste value.

[0086] [Table 4]

[0087] As is clear from the results in Table 4, the taste index of the wash-free rice of the present invention in Example 1 was 77.9. Thus, rice grains with the aleurone layer remaining on the surface of the grain clearly had a higher taste index than polished rice or brown rice from which the wax layer has been removed (wax-cut brown rice), and was almost the same as rice grains with the sub-aleurone layer remaining on the surface of the grain (kinmemai).

[0088] [Test Example 4] The resulting no-wash rice was examined for digestibility. Table 5 shows the results of comparing digestibility with that of golden germ rice and other varieties. The measurement method was a simulated gastric digestion test. 30 mL of 37°C artificial saliva (α-amylase 2.0 g / L, NaCl 0.117 g / L, KCl 0.14 g / L, NaHCO3 2.1 g / L) was added to 10 g of cooked rice and mixed for 2 minutes. After that, 150 mL of 37°C artificial gastric juice (Pepsin 1.0 g / L, NaCl 8.775 g / L, pH adjusted to 1.3 with sulfuric acid) was added and the mixture was shaken at 37°C for 180 minutes (stroke 40 mm, 120 rpm). The amount of residue was determined by draining the water through a tea strainer after the digestion test and weighing the residue remaining on the strainer. The rice was cooked in a rice cooker (RC-MF15, manufactured by Iris Ohyama Co., Ltd.), with water added according to the 1-go (1 cup) scale line on the rice cooker for every level cup of polished rice in the measuring cup provided, and cooked on the normal mode (not the quick cook mode). In terms of digestibility, it can be said that the smaller the amount of residue, the faster the digestion, and that the more residue there is, the more filling it will be. However, if the food is too poorly digestible, like brown rice (unprocessed), it can easily cause indigestion.

[0089] [Table 5]

[0090] As is clear from the results in Table 5, the residue amount for the wash-free rice of the present invention in Example 1 was 8.2 g. Thus, rice grains with the aleurone layer remaining on the surface of the grain are digested more slowly than polished rice and golden germ rice, but are more digestible than brown rice from which the wax layer has been removed (wax-cut brown rice), demonstrating that this rice is both digestible and filling.

[0091] [Test Example 5] The contents of γ-oryzanol, ferulic acid, and phytic acid in the wash-free rice of the present invention obtained in Example 1 were measured. The results are shown in Table 6. Table 6 also shows the contents in commercially available golden germ rice and wax-cut brown rice. These components were measured as follows. The γ-oryzanol content was measured by high-performance liquid chromatography at the Japan Food Fats and Oils Inspection Association, which was the client of the measurement. The total ferulic acid content was measured by high-performance liquid chromatography after hydrolysis using an alkaline solution at the Japan Food Research Laboratories. The phytic acid content was measured by high-performance liquid chromatography at Vegetec Co., Ltd.

[0092] [Table 6]

[0093] As shown in Table 6, the rinse-free rice of the present invention has a lower nutritional content than wax-cut brown rice and golden germ rice, but retains a higher concentration of the nutritional components of brown rice than golden germ rice.

Claims

1. Rice in which the aleurone layer is exposed over substantially the entire surface of the rice grain, (1) The exposed aleurone layer is the lowest layer or the lowermost part of the single or multiple layers of aleurone layers present in the rice grain before milling. (2) The α-amylase activity is 0.3 CU / g or more in a 1% by weight yield portion of the rice grain surface; This is a characteristic of milled rice.

2. 2. The polished rice according to claim 1, wherein 90% or more of the rice grains, by number, contain "germs with the surface portion of the germ scraped away," "scutellum, which is the basal portion of the germ left after the surface or protruding portion has been scraped away," or "groups of crushed cells."

3. 2. The polished rice according to claim 1, wherein the ash content is 2 g / 100 g or more in a 1% by weight yield portion of the surface of the rice grain.

4. The polished rice according to claim 1, having a whiteness of 33 to 43.

5. The milled rice according to claim 1, wherein the yellowness of the cooked rice when the milled rice is cooked is 15 to 22.

6. The polished rice according to claim 1, wherein the yield rate is 91% or more and 94% or less.

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