JP7807777B2 - Manufacturing method for functional rice processed foods - Google Patents

Description

The present invention relates to a method for producing functional processed rice foods that imparts indigestibility and anti-dementia properties to processed rice foods.

Japan's annual national medical expenses exceed 40 trillion yen, approximately one-sixth of the population has diabetes or is at risk of developing it, and there are approximately 4.6 million people with dementia, a number that is expected to increase further in the future. While the development of treatment technologies and pharmaceuticals for diseases is currently necessary, it is also important to prevent disease through diet.

Rice is a staple food in Japan and is eaten at least once a day. While rice has traditionally been considered a source of calories as a staple food, it has been reported that it contains many functional components, such as gamma-oryzanol, phytic acid, ferulic acid, and dietary fiber, with brown rice being particularly rich in these compounds (Non-Patent Document 1). Brown rice is also known to be rich in vitamins. Traditionally, before the Edo period, rice was primarily eaten as brown rice, but with the advent of the Edo period, the consumption of white rice spread, primarily in Edo. While the appearance and taste of cooked rice improved, this also led to the onset of beriberi, a disease caused by vitamin deficiency that became known as "Edo disease" (Non-Patent Document 2).

Eating brown rice is said to be good for your health because it provides many functional ingredients, such as the aforementioned gamma-oryzanol, phytic acid, ferulic acid, and dietary fiber, and recent research has also shown that it may help prevent diabetes and dementia (Non-Patent Document 3).

However, brown rice has a surface covered with the seed coat, which means it has poor water absorption, and so it needs to be left to soak in water for a long time before cooking, necessitating techniques such as using a pressure cooker or cooking twice. Furthermore, the appearance and taste of the cooked rice are poor, so it has not yet become widely used.

Recent high-end electric rice cookers offer selectable rice cooking programs, such as a "brown rice course," which eliminates the need for special pressure treatment or pre-treatment, but they still have the drawbacks of taking a long time to cook and producing rice that is harder and less sticky than white rice.

Next, looking at types of rice, black rice and red rice are known to be rich in polyphenols. Black rice is brown rice that has a purple-black color due to the accumulation of polyphenols such as anthocyanins in the outer layer of the grain, while red rice is brown rice that has a red color due to the accumulation of polyphenols such as procyanidins in the outer layer of the grain. Both types are widely distributed in East Asian and Southeast Asian countries, including Japan, China, Korea, and Thailand, and have long been considered to be rich in nutrients in China and other countries, and are considered to be medicine and food for a long time (Non-Patent Document 4). Research at Niigata University has also reported the antioxidant properties of the pigments in black rice and red rice (Non-Patent Document 5).

However, when black rice or red rice is eaten as brown rice, it has the aforementioned poor water absorption properties, which can result in poor appearance and taste, and the strong astringent taste caused by polyphenols. Therefore, it is recommended to use black rice or red rice as 70% or 50% polished rice rather than brown rice (Non-Patent Document 6).

Furthermore, various functional foods with antioxidant properties have been developed to prevent lifestyle-related diseases. Among these, black soybeans, red cabbage, and black rice are considered promising ingredients for foods with antioxidant properties. Furthermore, the addition of indigestible dextrin and polyphenols is considered promising for preventing diabetes, and the intake of omega-3 fatty acids, vitamins, amino acids, polyphenols, and other nutrients is recommended for preventing dementia (Non-Patent Document 7).

Against this background, few brown rice foods have been reported to date that simultaneously prevent postprandial blood glucose elevation and amyloid-β production, apart from one by the present inventors (Non-Patent Document 1). Furthermore, it has been considered extremely difficult to achieve both the good taste desired by consumers and the multiple functionalities required by the medical field (Patent Document 1).

In addition, there has been a method for producing ingredient-enriched brown rice (Patent Document 2) in which brown rice is soaked in water that is at least 50% by mass of the amount of the brown rice and pressurized to cause the bran components to migrate from the bran to the endosperm, thereby enriching the endosperm with the bran components. This method includes a soaking step in which brown rice is soaked, and a draining step in which the brown rice is drained after the soaking step. In the soaking step, a fiber-degrading enzyme is added to the soaking water, and the soaking water is kept at a temperature within the range of 40°C to 60°C. Patent Document 3: "A method for processing brown rice into easy-to-eat brown rice in a short time without damaging functional ingredients such as gamma-aminobutyric acid contained in the bran layer" (Patent Document 3); "A method for manufacturing functional rice in which organic germinated brown rice is mixed with a 20 to 40% by mass ratio of naturally derived nutrients, and the rice is stirred by elevating and rotating to allow the nutrients to be absorbed into the rice grains, and then the rice is dried with hot air" (Patent Document 4); "A method for manufacturing functional rice in which organic germinated brown rice is mixed with a 20 to 40% by mass ratio of naturally derived nutrients, and the rice is stirred by elevating and rotating to allow the nutrients to be absorbed into the rice grains, and then the rice is dried with hot air" (Patent Document 5); Patent Document 5: a technology for producing a food product containing six raw materials, namely, glutamic acid peptide, purple sweet potato powder, and hawthorn extract, by premixing the raw materials, shaping them in a structured manner under high temperature and pressure in a twin-screw extruder, and then drying, removing dust, and packaging; a technology for converting gingerols in raw materials derived from Zingiberaceae plants into shogaols by heating the raw materials directly or after mixing them with a fermentation liquid at a temperature of 30°C to 90°C and a humidity of 50% to 90% for 120 to 500 hours, thereby enriching the shogaols; a technology for filtering or centrifuging treated water from pigmented rice to remove microorganisms and suspended solids, and then repeatedly using the treated water as treated water, which includes a washing step and a GABA accumulation step; a functional food characterized by containing γ-aminobutyric acid and polyphenols (Patent Document 8); a technology for enriching brown rice, polished rice, and rice bran rich in functional ingredients by using subcritical or supercritical ethanol; Patent Document 9: a completely novel and excellent antioxidant composition according to the present invention, extracted using a rice grain (polished rice, etc.) and arabinogalactan having antidiabetic activity imparted to the rice grain (Patent Document 10); a method for producing a functional material, characterized in that rice bran, defatted rice bran, or brown rice is treated with an enzyme system containing a hemicellulase enzyme, a liquefying enzyme, and a saccharifying enzyme, and then treated with yeast (Patent Document 11); brown rice, 1 to 9 A method for producing enriched rice in which water and fortified substances such as vitamins, amino acids, minerals, brown rice components, mushroom components, soybean components, and herbal components are added to rice heated to 50 to 100°C, such as partially milled rice, germ rice, polished rice, germinated brown rice, processed rice, and rinse-free rice, while rotating and/or stirring (Patent Document 12); a method for producing enriched rice in which starch such as polished non-glutinous rice flour, polished glutinous rice flour, white bran, wheat flour, corn flour, refined starch, and dextrin are added to brown rice and/or ground brown rice, and curdlan, glucomannan, A technology for producing artificial rice for enriching brown rice components by extruding a mixture of gelling agents such as gelatin gellan gum, gum arabic, guar gum, agar, alginic acid, locust bean gum, etc., and, if necessary, useful components derived from rice such as inositol, γ-aminobutyric acid, γ-oryzanol, and ceramide, using an extruder and cutting the mixture (Patent Document 13); a technology for enriching polished rice with ceramide by 0.0003 to 0.0015%; Published patent documents include processed rice enriched with brown rice skin-beautifying ingredients (Patent Document 14), processed glutinous rice in which inositol, gamma-aminobutyric acid, and gamma-oryzanol are added to polished glutinous rice and glutinous rice foods derived from it (Patent Document 15), and a brown rice ingredient enhancer containing inositol, gamma-aminobutyric acid, and gamma-oryzanol as active ingredients to be added to polished rice or processed foods thereof to make the nutritional value similar to that of brown rice (Patent Document 16).

Patent application 2020-150996 Japanese Patent Application Laid-Open No. 2017-217015 JP 2017-112881 A Patent No. 6067080 JP 2015-517298 A JP 2011-32248 A JP 2011-30481 A JP 2009-201383 A Japanese Patent Application Laid-Open No. 2007-223990 Japanese Patent Application Laid-Open No. 2006-182738 Japanese Patent Application Laid-Open No. 2005-263722 Japanese Patent Application Laid-Open No. 2005-095070 Japanese Patent Application Laid-Open No. 2002-233317 Japanese Patent Application Laid-Open No. 2002-125605 Japanese Patent Application Laid-Open No. 2002-010743 Japanese Patent Application Laid-Open No. 2001-352918

Kenichi Otsubo: Characteristics and Selection of Rice Depending on Use, Journal of the Japanese Society of Food Science and Technology, Vol. 51, No. 5, pp. 40-46, 2018. Edited by Tadao Kurata et al.: Nutrition in Japan, pp.22-25, Basic Nutrition (Tokyo Kagaku Dojin, 2004) Hiroaki Masuzaki et al.: Improvement of brain function and prevention of diabetes by functional components of brown rice, Biotechnology, Vol. 95, No. 5, 244-247, 2017 Tomio Igaya: Purple Black Rice, pp.132-134, Red Rice, Purple Black Rice, Fragrant Rice (Nobunkyo, 2000) Mitsutoshi Ito et al.: Measurement of antioxidant capacity and polyphenol content of pigmented rice, Journal of the Japanese Society for Food Science and Technology, Vol. 58, No. 12, 576-582, 2011 Takahashi Motoko: What is the origin of the color of red rice and purple-black rice?, pp.62-62, All Questions about Rice and Rice (Kodansha, 2004) Dementia and Functional Foods (Fuji Medical Publishing, edited by Toshikazu Yoshikawa, 2018)

The present invention aims to provide a new functional processed rice food that combines the ability to suppress postprandial blood glucose elevation due to its resistance to digestion with the ability to prevent dementia due to its antioxidant properties and β-secretase inhibitory activity.

After extensive research, the inventors discovered that by simultaneously extracting both water-soluble and fat-soluble functional components from rice bran, particularly from pigmented rice bran, using an aqueous solution containing a surfactant and adding the extracted components to rice, it is possible to obtain a processed rice food that is endowed with the combined functionality of indigestibility and anti-dementia properties, leading to the invention of the present invention.

In other words, the method for producing functional processed rice foods of the present invention is characterized by comprising an extraction step in which components contained in the rice bran of pigmented rice are extracted with an aqueous surfactant solution to obtain an extract, and a processing step in which the extract obtained from this extraction step is used to produce a processed rice food.

Furthermore, the pigmented rice is black rice or red rice.

Furthermore, the processed rice food is cooked rice, and the raw rice for the cooked rice is black rice and/or extra-hard rice.

Furthermore, the processed rice food is characterized in being one of cooked rice, bread, noodles, sweets, and beverages.

Furthermore, the processed rice food is characterized in that the raw material rice is brown rice, partially milled brown rice, or germinated brown rice.

The surfactant is also characterized in that it is any one of sucrose fatty acid ester, glycerin fatty acid ester, calcium stearoyl lactylate, sorbitan fatty acid ester, and propylene glycol fatty acid ester.

Furthermore, in the extraction process, rice bran obtained by polishing black rice or red rice to a polishing yield of 85 to 99% by mass is added to an aqueous surfactant solution with an HLB of 3 to 16 at a ratio of 1 to 20% by mass, and the solution is soaked at a temperature of 30 to 80°C for 10 minutes to 24 hours, after which the solids are removed to obtain the extract.

Furthermore, in the extraction step, rice bran obtained by polishing waxy black rice or waxy red rice to a polishing yield of 85-95% by mass is added at a ratio of 5-20% by mass to an aqueous sucrose fatty acid ester solution having an HLB of 6-13, and the solution is soaked at a temperature of 40-60°C for 30 minutes to 18 hours, after which the solids are removed to obtain the extract. In the processing step, 100-2000% by mass of the extract is added to raw rice blended with 20% or more by mass of pigmented brown rice or processed brown rice products and extra-hard brown rice or processed brown rice products, and the resulting rice is cooked.

Furthermore, in the extraction step, rice bran obtained by polishing waxy black rice or waxy red rice to a polishing yield of 85-95% by mass is added to an aqueous sucrose fatty acid ester solution with an HLB of 6-13 at a ratio of 5-20% by mass, and the solution is soaked at a temperature of 40-60°C for 30 minutes to 18 hours, after which the solids are removed to obtain an extract. In the processing step, the processed rice food is obtained using the extract and raw material rice blended with pigmented brown rice or processed brown rice products and extra-hard brown rice or processed brown rice products in proportions of 20% by mass or more each.

Furthermore, in the extraction step, rice bran obtained by polishing black rice or red rice to a polishing yield of 85-99% by mass is added at a ratio of 1-20% by mass to an aqueous surfactant solution with an HLB of 3-16, and the solution is soaked at a temperature of 30-80°C for 10 minutes to 24 hours, after which the solids are removed to obtain the extract; and in the processing step, 100-2000% by mass of the extract is added to raw rice blended with 5-60% by mass of pigmented brown rice or processed brown rice products, and the rice is subjected to high-pressure treatment at 200 MPa or higher and then cooked.

Furthermore, in the extraction step, rice bran obtained by polishing waxy black rice and/or waxy red rice to a polishing yield of 85-95% by mass is added to an aqueous sucrose fatty acid ester solution having an HLB of 6-13 in a ratio of 5-20% by mass, and the mixture is soaked at a temperature of 40-60°C for 30 minutes to 24 hours. The extract and solid matter are then obtained by filtration and/or centrifugation, and the processed rice food is obtained in the processing step using raw material rice blended with pigmented brown rice and/or processed brown rice products and extra-hard brown rice and/or processed brown rice products in a ratio of 20% by mass or more each, the extract, and the solid matter.

Furthermore, in the extraction step, rice bran obtained by polishing black rice or red rice to a polishing yield of 85-99% by mass is added at a ratio of 1-20% by mass to an aqueous surfactant solution with an HLB of 3-16, and the solution is soaked at a temperature of 30-80°C for 10 minutes to 24 hours, after which the solid matter is separated to obtain the extract and the solid matter; and in the processing step, 100-2000% by mass of the extract and 0.5-10% by mass of the solid matter are added to raw rice blended with 5%-60% by mass of pigmented rice, and the mixture is subjected to high-pressure treatment at 200 MPa or more before being cooked.

Furthermore, the processing step is characterized by using pigmented rice with a polishing yield of 95% or more.

Furthermore, the processed rice food obtained in the processing step is characterized by its ability to suppress postprandial blood glucose elevation due to its indigestibility, its antioxidant properties, and its ability to prevent dementia due to its β-secretase inhibitory activity.

This invention makes it possible to provide functional processed rice foods that are expected to have the combined function of preventing diabetes and dementia, and that have good taste and appearance. This is expected to contribute to maintaining and improving the health of the nation, preventing disease, and improving quality of life through food.

1 shows a photograph of cooked pigmented rice and a graph showing an example of measurement of the physical properties of cooked rice by an integrated load test using a tensipresser. This is a photo of various types of partially milled rice mixed together. 1 is a photograph showing the measurement of anthocyanin content by the pH differential method. Photographs showing the difference in appearance of cooked rice due to differences in raw rice and rice cooking liquid. This is a photograph showing the state of adding black rice bran directly during cooking. This is a photograph of bread made using cooked rice that has been added with black rice bran extract. This is a photograph of cooked rice with black rice bran extract added and then high-pressure treated, and the color extract. 1 is a photograph of bread made with the addition of red rice bran extract. These are photographs of the cross sections of various types of bread made with the addition of various types of pregelatinized rice flour and using aqueous solutions extracted from various types of rice bran as the hydration liquid during bread making. Photographs of packed rice prepared by mixing black rice, extra-hard rice, and regular rice in a ratio of 4:4:2, adding 2.5% by mass of black glutinous rice extract and extraction residue, and cooking the rice, as well as packed rice prepared by comparison using regular cooked white rice.

The method for producing functional processed rice foods of the present invention includes an extraction step in which components contained in the rice bran of pigmented rice are extracted with an aqueous surfactant solution to obtain an extract, and a processing step in which the extract obtained from this extraction step is used to produce a processed rice food.

Known examples of pigmented rice include black rice and red rice. Black rice refers to brown rice that contains an anthocyanin-based purple-black pigment in at least one of the seed coat or pericarp, and includes what is known as purple black rice or purple rice. The anthocyanin-based purple-black pigment found in pigmented rice, and particularly in black rice, is a type of polyphenol known to have strong antioxidant properties. Therefore, including pigmented rice in foods can be expected to have a preventative effect against dementia.

Pigmented rice bran can be obtained by polishing pigmented brown rice using a rice polisher or similar. There are no particular restrictions on the yield during polishing, but it is preferable to keep it between 85 and 99% in order to increase the concentration of functional ingredients contained in the rice bran.

The surfactant used to extract the components contained in the rice bran of pigmented rice is not limited to any particular type, as long as it is a food additive. For example, sucrose fatty acid esters, glycerin fatty acid esters, calcium stearoyl lactylate, sorbitan fatty acid esters, and propylene glycol fatty acid esters can be used as surfactants.

Processed rice foods that can be produced using this invention include, for example, cooked rice, bread, noodles, sweets, and beverages, but a wide variety of other foods can also be produced using this invention.

When the processed rice product is cooked rice, black rice or extra-hard rice can be used as an ingredient in processed rice foods.

Ultra-hard rice refers to rice with long-chain amylopectin, and is known to be difficult to digest. For this reason, adding ultra-hard rice, which has the effect of suppressing post-meal blood sugar rise, to foods can be expected to have a preventative effect on diabetes. In addition, because ultra-hard rice has strong antioxidant properties, adding ultra-hard rice to foods can also be expected to have a preventative effect on dementia.

When using rice as an ingredient in processed rice foods, brown rice, partially milled brown rice, or germinated brown rice can be used as the raw material. In particular, using pigmented rice with a milling yield of 95% or more is expected to have a high dementia prevention effect.

Next, we will explain the method for producing the functional processed rice food of the present invention.

In the extraction process, components contained in pigmented rice bran are extracted with an aqueous surfactant solution to obtain an extract. For example, rice bran obtained by polishing black rice or red rice to a polishing yield of 85-99% by mass can be added at a ratio of 1-20% by mass to an aqueous surfactant solution with an HLB of 3-16, soaked at a temperature of 30-80°C for 10 minutes to 24 hours, and then the solids are removed to obtain an extract. Alternatively, rice bran obtained by polishing waxy black rice or waxy red rice to a polishing yield of 85-95% by mass can be added at a ratio of 5-20% by mass to an aqueous sucrose fatty acid ester solution with an HLB of 6-13, soaked at a temperature of 40-60°C for 30 minutes to 18 hours, and then the solids are removed to obtain an extract. Solids can be removed by conventional methods such as filtration or centrifugation.

In the processing step, the extract obtained in the extraction step is used to produce processed rice foods. For example, cooked rice or rice porridge containing functional ingredients can be produced by adding 100 to 2,000% by mass of the extract to raw rice containing 20% or more by mass of pigmented brown rice or processed brown rice products, and extra-hard brown rice or processed brown rice products, and cooking the rice. Alternatively, various processed rice foods can be produced using raw rice containing 20% or more by mass of pigmented brown rice or processed brown rice products, and extra-hard brown rice or processed brown rice products, and the extract obtained in the extraction step. Furthermore, cooked rice or rice porridge containing functional ingredients can be produced by adding 100 to 2,000% by mass of the extract to raw rice containing 5 to 60% by mass of pigmented brown rice or processed brown rice products, subjecting the rice to high-pressure treatment at 200 MPa or higher, and cooking the rice.

The processed rice food obtained by this invention has the ability to suppress postprandial blood glucose elevation due to its indigestibility, antioxidant properties, and dementia prevention properties due to its β-secretase inhibitory activity.

Although brown rice and processed brown rice products such as partially milled brown rice are inferior in appearance and taste to polished rice, they are known to contain a variety of functional components, such as dietary fiber, vitamins, and minerals, which are abundant in the bran layer. In the present invention, brown rice can be used as the raw material rice, and the processing can include rice that retains a certain amount of the bran layer during the polishing process, such as 70% milled rice or 50% milled rice; brown rice that has had cracks created on the surface through physical treatments such as high-temperature treatment or drying; or brown rice that has been biologically treated to improve its water absorption and functionality, such as germinated brown rice. The present invention further enhances the functionality of rice processed foods by extracting various water-soluble and fat-soluble functional components contained in the bran layer of brown rice and adding them to brown rice or processed brown rice products.

Rice bran contains water-soluble functional ingredients such as B vitamins, enzyme-inhibiting proteins, and polyphenols, as well as fat-soluble functional ingredients such as vitamin E and gamma-oryzanol. Functional ingredients that are particularly important for the "rice processed food that combines the effects of suppressing postprandial blood glucose elevation and preventing dementia," which is the objective of this invention, include dietary fiber, amylose, polyphenols, and amylase inhibitors in terms of suppressing postprandial blood glucose elevation, and antioxidant ingredients such as polyphenols, gamma-oryzanol, ferulic acid, and vitamin E, as well as polyphenols and protease inhibitors that inhibit beta-secretase, which is involved in the production of amyloid beta peptide, in terms of preventing dementia.

One way to enhance the functionality of processed rice foods is to add rice bran directly, but it is impossible to add large amounts to the raw brown rice, and this poses a fundamental problem: it reduces the value of the processed food, particularly in terms of taste and appearance. In contrast, in this invention, both the water-soluble and fat-soluble functional components contained in rice bran are efficiently extracted using warm water containing a surfactant, and then added to brown rice or processed brown rice products during processing such as cooking or bread making, thereby imparting multiple functionalities without compromising appearance or taste.

If necessary, adding both the aforementioned rice bran extract and the solid matter separated from the extract as the extraction residue to the raw rice and cooking or processing it is also effective in enhancing the functionality of the resulting processed rice food.

In this case, compared to adding the same amount of rice bran directly, the extraction process results in an increase in free pigments, gamma-aminobutyric acid (GABA), free ferulic acid, and other substances due to enzymatic reactions during the extraction process.

By adding the extraction residue along with the extract, it becomes possible to add functional ingredients such as dietary fiber and polymeric pigment components that were not extracted to the product, further enhancing the functionality-enhancing effect of this invention.

The effectiveness of extracting functional components can be further enhanced by adding a surfactant to the extract, and by setting the extraction temperature at 30-80°C, more preferably 50-70°C, the extraction efficiency can be increased without thermal inactivation of functionality.

The effects of this invention are even more pronounced when black rice, which is rich in polyphenols, or resistant, extra-hard rice is used as the raw material rice. By blending multiple new rice traits as raw materials, such as black rice such as blackberry, red rice such as Benika, hard rice such as Indica rice, and extra-hard rice such as Goami-2 or EM10, which have long-chain amylopectin, the composite functionality of the processed product can be further enhanced.

The present invention can be applied to brown rice, but when applied to partially milled rice or germinated brown rice, where only a small portion of the outer layer of the brown rice has been removed, it can produce a functional processed rice food with good taste. Furthermore, the use of partially milled rice increases the penetration of the various functional components contained in the bran into the raw material brown rice processed product, further improving the functionality-imparting effect.

The effects of the present invention are further enhanced by subjecting the rice to high-pressure treatment at 200 MP or more before cooking. In addition to improving the taste of cooked rice by reducing its hardness and increasing its stickiness, the high-pressure treatment promotes the solubilization of functional components such as polyphenols and ferulic acid, further improving functionality such as antioxidant properties and β-secretase inhibitory activity.

Regular rice may be used as the type of rice bran used in the present invention, but black rice such as "Okunomurasaki," which is particularly rich in anthocyanins, and red rice such as "Benisarasa," which is rich in procyanidins, are particularly preferred. In view of the fatty acid composition of the oils and fats contained in the rice bran, glutinous, pigmented rice is most preferred, and suitable examples include "Asamurasaki," commercially available glutinous black rice from Toyama Prefecture, and Benika, commercially available glutinous red rice from Kumamoto Prefecture.

The present invention makes it possible to produce a variety of functional processed rice foods, such as cooked rice, bread, noodles, sweets, and beverages, that have good taste and also have the combined effect of preventing diabetes and dementia.

The present invention will be explained in more detail below based on examples. Note that the present invention is not limited to the following examples.

(Evaluation of physicochemical properties and functionality of red rice and black rice)
Three types of brown rice pigments, namely the red/glutinous "Benikoh" variety, the red/non-glutinous "Benikasa" variety, and the black/glutinous "Shiho" variety, were cooked in an electric rice cooker with a water ratio of 1:1.5 (brown rice:water, by mass). The physical properties of the cooked rice were measured using a tensipresser (Figure 1).

As shown in Table 1, the red rice/glutinous rice "Henko" tended to have slightly higher tenderness and toughness than the black rice/glutinous rice "Shiho."

Separately from the above measurements, the gelatinization properties of cooked rice from the three types of pigmented rice mentioned above, as well as cooked rice from the black rice "Oku no Murasaki" cooked under the same conditions, were also measured. "Benika" showed a slightly higher retrogradation tendency than "Shiho," while "Beni Sarasa" showed a retrogradation tendency that was approximately 2 to 3 times higher than "Benika" and "Shiho," similar to the black rice "Oku no Murasaki."

The antioxidant properties of cooked rice from the three types of pigmented rice mentioned above, as well as cooked rice from the black rice variety "Oku no Murasaki" and cooked rice from Koshihikari, cooked under the same conditions, were also measured.

As shown in Table 2, the H-ORAC values, an index of water-soluble antioxidant activity, were approximately 2 to 4 times higher for the red rice varieties "Benikoh" and "Benikarasa" than for the black rice varieties "Shiho" and "Okunomurasaki." The L-ORAC value, an index of fat-soluble antioxidant activity, was highest for "Okunomurasaki," with "Benikoh" showing a value approximately 1.2 times higher than "Shiho."

As mentioned above, antioxidant components are believed to be effective in preventing the onset of dementia (Non-Patent Document 7), and in that sense, pigmented rice such as black rice and red rice is thought to be promising for preventing the onset of dementia.

(Physical properties of cooked rice mixed with partially milled rice)
Based on a mixture of partially milled black rice (Okunomurasaki), partially milled extra-hard rice, and partially milled Koshihikari rice in a 4:4:2 ratio (by mass), various types of partially milled rice and unpolished brown rice were mixed and cooked to obtain partially milled rice mixed rice, as shown in Figure 2. The physicochemical properties and functionality of the resulting partially milled rice mixed rice were then evaluated.

As shown in Table 3, compared to the partially milled mixed cooked rice containing brown rice (black rice, brown rice, partially milled extra-hard rice, partially milled Koshihikari; 4:4:2), the partially milled mixed cooked rice without brown rice (partially milled black rice, partially milled extra-hard rice, partially milled Koshihikari; 4:4:2) had lower "hardness" and "firmness," and increased "adhesion" and "stickiness," resulting in improved physical properties.

In addition, when a mixture (by mass) of partially milled black rice, partially milled extra-hard rice, and partially milled Koshihikari rice was used, the physical properties of retort rice obtained by high-pressure cooking at 120°C were compared with those of aseptically cooked rice cooked at normal pressure. As shown in Table 3, the retort rice showed 1.2 to 1.6 times higher values for "hardness" and "firmness." Both showed roughly the same values for "adhesion." The retort rice showed 1.2 times higher values for "stickiness."

In this example, black rice with an 80% yield was prepared for comparison, but almost no pigment components remained, making it unsuitable for the purpose of achieving any expected functional effects.

In addition, when the free sugar content of partially milled rice was measured, it tended to be higher in the partially milled rice without brown rice compared to the partially milled rice with brown rice. However, it was found that the gamma-oryzanol, dietary fiber, and total ferulic acid content of the partially milled rice without brown rice was approximately 10% lower than that of the partially milled rice with brown rice. Furthermore, when rice was cooked with 1.8% unsalted miso added to the cooking water and when rice was cooked with 2.0% red onion added to the cooking water, these values were slightly lower in the partially milled rice without brown rice compared to the partially milled rice with brown rice.

In addition, when a mixture of partially milled black rice, partially milled extra-hard rice, and partially milled Koshihikari rice was used in a 4:4:2 ratio (by mass), the antioxidant properties of retort rice cooked under high pressure at 120°C and sterile cooked rice cooked at normal pressure were measured. The H-ORAC value was 1.2 times higher for the retort rice, while the L-ORAC values were nearly the same for both.

(β-secretase inhibitory activity of cooked rice mixed with partially milled rice)
The beta-secretase inhibitory activity of retort rice, which is believed to be effective in preventing the onset of dementia, was measured for the partially milled rice mixed rice obtained by high-pressure cooking at 120°C.

As a result, as shown in Table 4, when partly milled black rice, partly milled extra-hard rice, and partly milled Koshihikari rice were mixed in a 4:4:2 ratio (by mass), and when partly milled black glutinous rice and partly milled extra-hard rice were mixed in a 1:1 ratio (by mass), β-secretase inhibitory activity of 17.5% and 53.5%, respectively, was confirmed.

Alzheimer's disease, the most common form of dementia, is thought to be caused by β-secretase and γ-secretase cleaving amyloid precursor protein (APP) to produce Aβ, which forms senile plaques.

(Fatty acid composition of various types of brown rice bran)
Brown rice contains approximately 3% lipids, and rice bran oil has been reported to have antioxidant properties (ferulic acid, γ-oryzanol), immunostimulatory properties (phytic acid), and cholesterol-lowering properties (dietary fibers such as cellulose, hemicellulose, and pectin). Fatty acids include saturated fatty acids, unsaturated fatty acids, and highly unsaturated polyunsaturated fatty acids, and their reported functions include as components of biomembranes, energy sources, and lipid mediator precursors (ω-3 polyunsaturated fatty acids) (anti-inflammatory effects) (Non-Patent Document 7).

Therefore, the fatty acid composition of the bran from various types of brown rice, including "Koshihikari," "Black Rice Non-Glutinous," "Black Rice Glutinous," "Super Hard Rice," "Red Rice Non-Glutinous," and "Red Rice Mochi," was measured using gas chromatography. The results showed that "Koshihikari" and red rice had linoleic acid contents approximately 1.1 to 1.2 times higher than other varieties. Furthermore, black rice and super hard rice had oleic acid contents approximately 1.1 times higher than other varieties. "Black Rice Glutinous" and red rice had alpha-linolenic acid contents approximately 1.2 to 1.6 times higher than other varieties. Oleic acid, a representative omega-9 fatty acid, is synthesized in the body and has been reported to tend to lower LDL cholesterol levels. Linoleic acid, an omega-6 fatty acid, is an essential fatty acid that is not synthesized in the body and has been reported to tend to lower blood cholesterol levels. Additionally, alpha-linolenic acid, an omega-3 fatty acid, is also an essential fatty acid that, after entering the body, is metabolized to become EPA and DHA, and has been reported to help prevent lifestyle-related diseases, such as lowering blood triglycerides, preventing arteriosclerosis, and dementia. For this reason, it is estimated that mixing brown rice or bran from varieties with distinctive fatty acid compositions, such as black rice, red rice, extra-hard rice, and koshihikari, would further improve functionality.

(Investigation of methods for extracting functional components from rice bran)
A method for extracting functional components from rice bran was investigated using "black glutinous rice" bran. The bran was obtained by polishing brown black glutinous rice to a 90% yield using a grinding-type rice polisher (Satake TM-5). The extraction conditions were as follows:

A: Black rice glutinous rice bran distilled water extract (0.05 g/mL) for 1 hour
Black rice bran was extracted with distilled water at room temperature. The amount of bran in the extract was 0.05 g/ml, and the extraction time was 1 hour.

B: Black rice bran extract (0.05 g/mL) with distilled water at 50°C for 1 hour
Black rice bran was extracted with distilled water at 50° C. The amount of bran in the extract was 0.05 g/ml, and the extraction time was 1 hour.

C: Black rice glutinous rice bran extracted with distilled water at 90°C (0.05g/mL) for 1 hour
Black rice bran was extracted with distilled water at 90° C. The amount of bran in the extract was 0.05 g/ml, and the extraction time was 1 hour.

D: Black rice glutinous bran extract with distilled water at 50°C + 0.5% DK-ester (Dai-ichi Kogyo Seiyaku: F-10) (0.05 g/mL) for 1 hour
Black rice bran was extracted with a 0.5% DK-ester aqueous solution at 50° C. The amount of bran in the extract was 0.05 g/ml, and the extraction time was 1 hour.

E: Black rice glutinous rice bran methanol extraction (0.05 g/mL) for 1 hour
Black rice bran was extracted with room temperature methanol at a concentration of 0.05 g/ml for 1 hour.

F: Black rice bran 70% ethanol extraction (0.05 g/mL) for 1 hour
Black rice bran was extracted with 70% aqueous methanol solution at room temperature. The amount of bran in the extract was 0.05 g/ml, and the extraction time was 1 hour.

DK ester is a food-grade surfactant and was used to increase the extraction efficiency of fat-soluble functional components such as vitamin E and gamma-oryzanol from rice bran.

As a result, the absorbance at 520 nm for anthocyanins was A: 1.053, B: 1.266, C: 1.189, D: 1.394, E: 0.244, F: 1.456. The absorbance tended to decrease as the extraction temperature increased, and increased with the addition of the surfactant DK-ester, reaching its highest value with 70% ethanol extraction. For comparison, a surfactant with an HLB of 2 was also examined in this example, but it was found to be inappropriate due to its poor hydrophilicity and insufficient emulsifying properties. Furthermore, a surfactant with a highly hydrophilic HLB of 18 was found to be too water-soluble, resulting in poor emulsion stability and was also inappropriate.

(β-secretase inhibitory activity of fat-soluble components and 70% ethanol-soluble components)
We investigated whether the β-secretase inhibitory activity was due to anthocyanin, a type of polyphenol pigment found in black rice and brown rice (which suppresses the production of reactive oxygen species, prevents arteriosclerosis and thrombosis, and has preventive effects against ischemic heart disease and cerebrovascular disorders), or to rice oil (which contains ferulic acid, γ-oryzanol, and phytic acid) by changing the extraction solvent.

The β-secretase inhibitory activity of a 70% ethanol extract (pigment component) and a hexane extract (rice oil component) was measured for each of 5% black rice bran, 5% black rice non-glutinous bran, and 5% koshihikari bran. In the following explanation, "5% black rice bran," "5% black rice non-glutinous bran," and "5% koshihikari bran" refer to extractions containing 5% black rice bran by mass, 5% black rice non-glutinous bran by mass, and 5% koshihikari bran by mass, respectively.

As a result, as shown in Table 6, for each variety, 70% ethanol extracts exhibited inhibitory activity 1.6 to 7.4 times higher than hexane extracts, with 5% black rice bran (Oku no Murasaki) showing the highest value. Thus, for all samples, 70% ethanol extracts exhibited stronger inhibitory activity than hexane extracts, indicating that 70% ethanol-soluble polyphenols and other components contribute more than fat-soluble components such as gamma-oryzanol. Furthermore, when comparing fat-soluble components extracted with hexane, the hexane extract of 5% black rice bran exhibited values 5.2 times higher than 5% black rice bran and 1.3 times higher than 5% Koshihikari bran.

(β-Secretase inhibitory activity and antioxidant properties of black rice bran extract)
Black rice bran solutions containing 0.5%, 2.5%, 5.0%, 10%, and 30% black rice bran were extracted for 1 hour at 50°C using an aqueous solution containing 0.5% DK-ester as the solvent. These solutions were then freeze-dried and their β-secretase inhibitory activity was measured. In the following description, "0.5% black rice bran,""2.5% black rice bran,""5% black rice bran,""10% black rice bran," and "30% black rice bran" refer to extractions containing 0.5% by mass of black rice bran, 2.5% by mass of black rice bran, 5% by mass of black rice bran, 10% by mass of black rice bran, and 30% by mass of black rice bran, respectively. As a result, as shown in Table 7, the β-secretase inhibitory activity of 5% black rice bran was 1.06 times higher than that of 10% black rice bran, and 1.05 times higher than that of 2.5% black rice bran. A bran concentration of 0.5% was inappropriate because no inhibitory activity was detected, while a bran concentration of 30% was inappropriate because the concentration was too high and the mixture became clayey. Extraction temperatures below room temperature were inappropriate because of poor extraction efficiency, and temperatures above 90°C were inappropriate because of excessive evaporation.

In addition, 0.5% DK-ester was added to various 5% rice bran samples, and the antioxidant capacity (ORAC) of the extract obtained by extracting at 50°C for 1 hour was measured. For comparison, the antioxidant properties of rice bran were also measured.

As a result, as shown in Table 8, black rice bran (produced in Toyama) had a 3.3-fold higher H-ORAC value and an approximately 40% lower L-ORAC value than koshihikari bran (produced in Nagano). 5% black rice bran (produced in Toyama) extract had a 25% lower H-ORAC value and an approximately 8% lower L-ORAC value than black rice bran. 5% koshihikari bran (produced in Nagano) extract had a 23% lower H-ORAC value and an approximately 60% lower L-ORAC value than koshihikari bran. 5% black rice bran (produced in Toyama) had an approximately 3-fold higher H-ORAC value and an approximately 1.3-fold higher L-ORAC value than 5% koshihikari bran (produced in Nagano) extract. After examining the extraction time, it was determined that the extraction rate of pigment components was low after 5 minutes, and conversely, the extraction rate did not increase further even after 24 hours, making it unnecessary.

(Pigment content of cooked rice obtained by adding black rice bran extract)
5% black rice bran was extracted with an aqueous solution containing 0.5% DK-ester (50°C for 1 hour), and the extract was added to rice and cooked. The anthocyanin content of the cooked rice was measured using the pH differential method.

Figure 3 shows the pH differential method. In Figure 3, A represents a water extract of glutinous black rice bran, B represents glutinous black rice bran extracted with an aqueous solution containing DK-ester, C represents cooked rice made from a mixture of partially milled extra-hard brown rice, partially milled Okunomurasaki brown rice, and partially milled Koshihikari brown rice in a 4:4:2 ratio, D represents cooked rice made from the mixed brown rice of C, which was extracted (at 50°C for 1 hour) with an aqueous solution containing 5% glutinous black rice bran and 0.5% DK-ester, and then cooked, and E represents cooked rice under the same conditions as D, except that dietary fiber was added.

As a result, as shown in Table 9, the anthocyanin content of cooked rice (D), obtained by adding rice to an extract obtained by extracting (50°C for 1 hour) using an aqueous solution of 5% black rice bran and 0.5% DK-ester, was approximately three times higher than that of cooked rice (C) obtained by cooking in water.

(Antioxidative properties of cooked rice obtained by adding various bran extracts)
Various bran extracts were added to rice, and the cooked rice was then cooked, and the antioxidant capacity (ORAC) of the resulting cooked rice was measured.

For polished Koshihikari rice, various types of partially milled rice, and mixed partially milled rice, rice cooked with black rice (Okunomurasaki) glutinous rice bran extract (5% black rice bran) tended to have H-ORAC values 1.2 to 2.2 times higher than rice cooked with Koshihikari bran extract (5% Koshihikari bran). However, with the exception of polished Koshihikari rice and partially milled extra-hard rice, the L-ORAC values tended to be 0.6 to 0.84 times lower than rice cooked with Koshihikari bran extract (5% Koshihikari bran).

With the exception of polished Koshihikari rice, the total ORAC value of rice cooked with black rice (Okunomurasaki) bran extract (5% black rice bran) was approximately 1.8 to 2.4 times higher than rice cooked in water and soaked, and the total ORAC value of rice cooked with Koshihikari bran extract (5% Koshihikari bran) tended to be 1.1 to 1.5 times higher than rice cooked in water and soaked.

When the extract obtained by extracting 5% black rice bran with an aqueous solution containing 0.5% DK-ester (50°C for 1 hour) and adding it to partially milled mixed rice and cooking it, the resulting cooked rice had approximately twice the H-ORAC value and approximately 1.6 times the L-ORAC value compared to rice cooked in water. Furthermore, when the extract obtained by extracting 5% koshihikari bran with an aqueous solution containing 0.5% DK-ester (50°C for 1 hour) and adding it to partially milled mixed rice and cooking it, the H-ORAC value was approximately 5% higher and the L-ORAC value was approximately 1.9 times higher compared to rice cooked in water.

(Physical properties of cooked rice obtained by cooking mixed rice with various bran extracts)
Black rice bran extract (5% black rice bran) and Koshihikari bran extract (5% Koshihikari bran) were added at 150% by mass to partially milled mixed rice (ultra-hard rice (Goami-2): black rice (Okunomurasaki): Koshihikari = 4:4:2), and the rice was cooked. The physical properties of the resulting cooked rice were measured. As shown in Table 10, the physical properties of rice cooked with black rice bran extract (5% black rice bran) tended to be slightly higher in "hardness," slightly lower in "firmness," and 20 to 37% lower in "adhesion" and "stickiness" compared to rice cooked with water. Furthermore, the physical properties of rice cooked with Koshihikari bran extract (5% Koshihikari bran) were approximately 1.3 times higher in "hardness," slightly lower in "firmness," approximately 1.4 times higher in "adhesion," and slightly higher in "stickiness" compared to rice cooked with water. Furthermore, rice cooked with black rice bran extract (5% black rice bran) was approximately 20% lower in "hardness," had roughly the same "firmness," and was approximately 30-50% lower in "adhesion" and "stickiness" compared to rice cooked with Koshihikari bran extract (5% Koshihikari bran).

When the blending ratio of black rice and extra-hard rice in the raw rice was 10% or less, the effect of the blending on improving physical properties was insufficient and it was therefore inappropriate. Furthermore, when adding rice bran extract to the raw rice during cooking, if it was less than 100% by mass, the cooked rice would become hard and this was inappropriate, while if it exceeded 2000% by mass, it would be too thin even for use as porridge and was therefore also inappropriate.

(Differences in appearance, physical properties, and functionality of cooked rice due to differences in raw rice and cooking liquid)
As raw rice, 300 g of each of the following was used: (1) 100% Koshihikari brown rice, and (2) a mixed rice blend of black rice (Okunomurasaki), extra-hard rice (Goami-2), and Koshihikari brown rice in a mass ratio of 4:4:2.

15g of bran obtained by polishing brown rice (Okunomurasaki) to a 90% yield using a grinding rice polisher (Satake TM-5) was soaked in 450mL of a 0.1% DK-ester aqueous solution, and the liquid extracted at 70°C for 3 hours was filtered through gauze to serve as the rice cooking liquid.

Then, each type of raw rice was cooked in a rice to rice cooking liquid ratio of 1:1.5 using the white rice setting in an electric rice cooker (Panasonic SR-VSA180). For comparison, the mixed rice was also cooked under the same conditions using tap water as the rice cooking liquid.

The appearance of the three types of cooked rice obtained in this way is shown in Figure 4. As is clear from Figure 4, when cooked with tap water, the color of the cooked rice becomes lighter even when black rice is added (center of Figure 4), whereas even when the raw rice was 100% Koshihikari, the color of the cooked rice became darker when black rice bran extract was used as the cooking liquid (left side of Figure 4). Furthermore, when 40% black rice was added to the raw rice and black rice bran extract was used as the cooking liquid, the cooked rice had the darkest color (right side of Figure 4).

The physical properties of the cooked rice were also measured using the bulk method with a Taketomo Electric tensipresser, and the results are shown in Table 11. As is clear from Table 11, the hardness and firmness of the three types of cooked rice were roughly the same, but adhesion was strongest when Koshihikari brown rice was cooked with the extract, and stickiness was strongest when mixed rice was cooked with the extract. These results demonstrate that using black rice bran extract as a cooking liquid improves the adhesion and stickiness of cooked rice, resulting in a surprising improvement in taste.

Furthermore, these three types of cooked rice were dried with hot air at 60°C for five hours, then crushed, and the antioxidant properties of the liquid extracted with five times the amount of water or hexane were measured.

The results showed that the ORAC value of mixed rice cooked with the extract was the strongest at 217.3 (μmol TE/100g), followed by Koshihikari brown rice cooked with the extract at 112.4 (μmol TE/100g). The ORAC value of mixed rice cooked with tap water was the weakest of the three at 75.0 (μmol TE/100g). However, all three were significantly higher than the ORAC value of 1.1 for regular polished rice and 46 for regular brown rice, suggesting that the antioxidant properties may be effective in preventing the onset of various lifestyle-related diseases, including dementia. This demonstrates that using black rice bran extract as a cooking liquid can produce cooked rice with surprisingly strong antioxidant properties.

The reason for this is that when the anthocyanin content of the three types of dried cooked rice powder mentioned above was measured, the anthocyanin content was highest at 357 (μg/g) when mixed rice was cooked with the extract, followed by Koshihikari brown rice cooked with the extract at 103 (μg/g), and the value was 86 (μg/g) when mixed rice was cooked with tap water. Therefore, it is thought that the anthocyanin content in cooked rice increases significantly by using black rice bran extract instead of regular water as the cooking liquid.

(Difference in taste compared to rice cooked with direct addition of bran)
Black glutinous rice (commercially available) was used as the black rice. 300 g of a mixture of black rice, ultra-hard rice (Goami-2), and Koshihikari brown rice in a mass ratio of 4:4:2 was weighed out, and 450 mL of pure water was added and cooked. During cooking, 15 g of bran obtained by polishing the black glutinous brown rice to a 90% yield using a grinding rice polisher (TM-5 manufactured by Satake) was added directly to the 300 g of rice. The state of the black rice bran added before cooking is shown in Figure 5.

The rice obtained by directly adding black rice bran and cooking it was then subjected to a sensory test (based on six criteria: appearance, aroma, taste, hardness, stickiness, and overall evaluation) by five taste evaluation experts.

Here, cooked rice obtained by adding black rice bran extract and cooking it was assigned a score of 3 for all items and used as a control for comparison. The control rice was a 4:4:2 mixture of black rice (Okunomurasaki), extra-hard rice (Goami-2), and brown Koshihikari rice, weighed out at 300 g. Furthermore, 15 g of bran obtained by polishing brown black rice (Okunomurasaki) to a 90% yield using a grinding-type rice polisher (Satake TM-5) was immersed in 450 mL of a 0.1% aqueous solution of DK-Ester F-10, and the extract was left to extract for 3 hours at 70°C. The extract was then filtered through gauze and used as the cooking liquid.

The results are shown in Table 12. When black rice bran was added directly and cooked (direct bran addition), the bran remained as solid pieces on the surface of the cooked rice, resulting in a poor texture and lower ratings in appearance, stickiness, and overall evaluation, compared to when the extract was added and cooked (rice cooked with bran extract).

The physical properties of the two types of cooked rice were measured using a Taketomo Electric tensipresser, and the results are shown in Table 13. As with the sensory evaluation, it was shown that when cooked with black rice bran added directly, the rice was less sticky and sticky than when cooked with the extract added.

(Bread made using cooked rice cooked with black rice bran extract)
300 g of a mixture of black rice (Okunomurasaki), ultra-hard rice (Goami-2), and Koshihikari brown rice in a mass ratio of 4:4:2 was weighed and used as the raw rice. Furthermore, 15 g of bran obtained by polishing black rice (Okunomurasaki) brown rice to a 90% yield using a grinding rice polisher (Satake TM-5) was immersed in 450 mL of a 0.1% aqueous solution of DK-Ester F-160, and the resulting solution was extracted at 42 °C for 17 hours. The solution was filtered through gauze and used as the rice cooking liquid. The raw rice was then added with the cooking liquid and cooked to obtain black rice bran extract-cooked rice.

Next, 75g of cooked rice cooked with the black rice bran extract was added to 125g of strong wheat flour (Nisshin Flour Milling's Camellia), followed by 2.5 teaspoons of salt, 15g of butter, 15g of sugar, and 30g of skim milk. The mixture was then mixed for 15 minutes in a home bread machine (Panasonic SD-BH103), and 3g of dry yeast was added to make bread.

As a comparative example, bread was made under the same conditions as above, except that cooked rice was used in pure water as the rice cooking liquid.

A photograph of the resulting bread is shown in Figure 6. Compared to the comparative bread (right), the bread of the invention (left) was pale purple in color and was softer with a good texture. It was rich in antioxidants with a total ORAC value of 87.8 (μmol TE/100g FW), and had a high total dietary fiber content of 4.7% and a high total ferulic acid content of 27.0mg/100g, suggesting its potential for preventing the onset of lifestyle-related diseases.

(Noodles kneaded with black rice bran extract)
300 g of a mixture of black rice (Okunomurasaki), ultra-hard rice (EM10), and Koshihikari brown rice in a mass ratio of 4:4:2 was weighed and used as the raw rice. Furthermore, 15 g of bran obtained by polishing black rice (Okunomurasaki) brown rice to a 90% yield using a grinding rice polisher (Satake TM-5) was immersed in 450 mL of a 0.1% DK-ester aqueous solution, and the extract was left at 70°C for 3 hours. The extract was filtered through gauze and used as the rice cooking liquid. The rice cooking liquid was then added to the raw rice and cooked to obtain cooked rice containing the black rice bran extract.

Next, the cooked rice with the black rice bran extract was dried with hot air at 60°C for 5 hours and then pulverized. 125 g of the resulting powder was mixed with 100 g of commercially available strong flour (Nisshin Seifun Co., Ltd., Camellia), 25 g of gluten, and 2.5 g of salt, and 130 g of hot water was added. The mixture was then kneaded for 30 minutes using the "udon pasta mode" setting in a bread maker (Panasonic SD-BM151). The mixture was then placed in a plastic bag and placed in a household refrigerator and left overnight at 8°C. The next day, the mixture was rolled five times to a thickness of 3 mm using a pasta maker (Imperia), and a sheet was produced. 2.2 mm wide noodles were then cut using a cutting blade. The noodles were then boiled for 6 minutes in 5 L of hot water containing 2 g of salt and cooled for 1 minute in 20°C water.

The noodles retained their purple color even after boiling and had a good texture.

(Physical properties of partially milled black rice cooked after high-pressure treatment)
To determine the optimal high-pressure treatment, Koshihikari brown rice was treated at 100 MPa or 200 MPa, and the polyphenol content was measured using the Folin-Ciocalteu method. The results showed that without high-pressure treatment, the polyphenol content was 4.98 mg GAE/100 g FW, with 100 MPa it was 5.07 mg GAE/100 g FW, and with 200 MPa it was 5.36 mg GAE/100 g FW, indicating that high-pressure treatment of 200 MPa or higher was effective. Therefore, treatment at 200 MPa was performed from this point onward.

420 mL of black glutinous rice bran extract was added to 300 g of raw rice, which was a mixture of partially milled extra-hard rice, partially milled Okunomurasaki rice, and partially milled Koshihikari rice in a mass ratio of 4:4:2. The black glutinous rice bran extract was prepared by extracting black glutinous rice bran (0.05 g/mL) with a 0.5% DK-ester (Dai-ichi Kogyo Seiyaku: F-10) aqueous solution at 50°C for 1 hour.

Next, the rice was cooked under the following conditions:

A: Rice cooked with black glutinous rice bran extract B: Rice cooked with water C: Rice cooked with black glutinous rice bran extract and 6g of rice oil added D: Rice cooked with water after adding 15g of black glutinous rice bran and 6g of rice oil directly E: Rice cooked under the same conditions as A above after high-pressure treatment The high-pressure treatment was carried out by sealing the raw material rice and black glutinous rice bran extract in a plastic tray using a high-pressure treatment device manufactured by High Pressure Support Co., Ltd. at a treatment temperature of 50°C for 15 minutes of pressure increase, 10 minutes at a constant pressure of 200 MPa, and 15 minutes of pressure decrease. After high-pressure treatment, the tray was removed and the rice was cooked at normal pressure.

After cooking, all cooked rice samples were kept at 25°C for 2 hours, and then the physical properties of the cooked rice were measured using a tensipresser.

The results are shown in Table 14. Compared to Comparative Example B (rice cooked in water), Example A had the same hardness, but significantly more adhesion and stickiness, and had a better taste. In Example C, which was cooked under the same conditions as Example A but with rice oil added during cooking, the stickiness was even less than Comparative Example B. In Example D, in which the same amount of black rice bran was added directly during cooking instead of black rice bran extract, the stickiness was less than B, and the physical properties of the cooked rice were significantly inferior to Example A. In Example E, which was cooked with black rice bran extract like Example A and then subjected to high-pressure treatment before cooking, the hardness and firmness of the cooked rice were less than A, and the adhesion and stickiness were greater, resulting in cooked rice with the best taste.

Photographs of the cooked rice of Comparative Example B and Invention Example E, as well as the pigment extract (40% aqueous methanol solution containing 0.5% trifluoroacetic acid) from these cooked rice, are shown in Figure 7. As is clear from Figure 7, Example E, which was cooked after blending partially milled black rice and high-pressure treatment, showed that the high-pressure treatment penetrated more thoroughly from the surface to the interior of the partially milled brown rice, resulting in significantly darker colors for the cooked rice and extract.

(The health benefits of partially milled black rice cooked after high-pressure treatment)
Black rice-blended cooked rice treated in the same manner as in Example 15 was freeze-dried using a freeze dryer FD-1000 manufactured by Tokyo Rikakikai Co., Ltd., and the antioxidant activity and β-secretase inhibitory activity were measured. The antioxidant activity was measured using a microplate reader based on the ORAC value using Trolox, and the β-secretase inhibitory activity was measured using a SensoLyte 520 β-secretase assay kit (Cosmo Bio).

As a result, as shown in Table 15, invention examples A, C, and E had significantly stronger antioxidant and β-secretase inhibitory activity than comparative example B, and also had a higher resistant starch content.

(Bread made by adding rice flour to wheat flour and using red non-glutinous rice bran extract for water addition)
Koshihikari rice was used as the starting material. It was cooked under standard conditions in an electric rice cooker, dried at 60°C for 6 hours, coarsely crushed in a coffee mill, and finely pulverized in a UDY cyclone mill to prepare pregelatinized rice flour. 62.5 g of this rice flour was mixed with 187.5 g of strong wheat flour (Nisshin Seifun's Camellia brand), and then mixed with 10 g of commercially available rice oil, 17 g of sugar, 6 g of skim milk, and 5 g of salt. Bread was made using the straight method in a Panasonic home bread maker (SD-BH103). While 195 mL of water was added during bread making, bread was also made using pure water and rice bran extract for comparison. The rice bran extract was prepared by extracting commercially available waxy red rice bran (0.05 g/mL) from Nagano Prefecture with a 0.5% aqueous solution of DK-ester (Dai-ichi Kogyo Seiyaku: F-10) at 50°C for 1 hour.

As a result, as shown in Figure 8, bread-making properties were significantly better when red rice bran extract was added (right) than when pure water was added (left).

(Bread made with pregelatinized rice flour and water using rice bran extract for color)
Various types of bread A to M were produced using the same production method as in Example 17, except for the conditions below. Note that, as in Example 17, 25% pregelatinized Koshihikari rice flour was added to breads B to M, except for bread A.

A is a comparative example, in which 100% strong wheat flour (Nisshin Flour Milling's Camellia) was used without adding pregelatinized rice flour, and pure water was used for hydration.

B: 75% strong wheat flour with 25% pregelatinized rice flour added, and pure water was used for the hydration during bread making. The pregelatinized rice flour was prepared by cooking polished Koshihikari rice, freeze-drying it, and then grinding it.

As with B, C was made by adding 25% pregelatinized rice flour derived from the same Koshihikari cooked rice to 75% strong wheat flour, and the hydration used during bread making was a rice bran extract obtained by extracting Koshihikari rice bran (0.05 g/mL) with a 0.5% aqueous solution of DK-ester (Dai-ichi Kogyo Seiyaku: F-10) at 50°C for 1 hour.

As with B, D was made by adding 25% pregelatinized rice flour derived from the same Koshihikari cooked rice to 75% strong wheat flour, and the hydration used during bread making was a rice bran extract obtained by extracting non-glutinous red rice bran (0.05 g/mL) with a 0.5% aqueous solution of DK-ester (Dai-ichi Kogyo Seiyaku: F-10) at 50°C for 1 hour.

As with B, E was made by adding 25% pregelatinized rice flour derived from the same Koshihikari cooked rice to 75% strong wheat flour, and the hydration used during bread making was a rice bran extract obtained by extracting red rice glutinous rice bran (0.05 g/mL) with a 0.5% aqueous solution of DK-ester (Dai-ichi Kogyo Seiyaku: F-10) at 50°C for 1 hour.

F, like B, is made from 75% strong wheat flour and 25% pregelatinized rice flour derived from the same Koshihikari cooked rice. For hydration during bread-making, a rice bran extract was used, prepared by extracting non-glutinous black rice bran (0.05 g/mL) with a 0.5% aqueous solution of DK-ester (Dai-ichi Kogyo Seiyaku: F-10) at 50°C for 1 hour.

As with B, G was made with 75% strong wheat flour and 25% pregelatinized rice flour derived from the same Koshihikari cooked rice. The hydration used during bread-making was a rice bran extract obtained by extracting black rice bran (0.05 g/mL) with a 0.5% aqueous solution of DK-ester (Dai-ichi Kogyo Seiyaku: F-10) at 50°C for 1 hour.

As with B, H is made from 75% strong wheat flour and 25% pregelatinized rice flour derived from the same Koshihikari cooked rice. The water added during bread-making was a rice bran extract obtained by extracting ultra-hard rice bran (0.05 g/mL) with a 0.5% aqueous solution of DK-ester (Dai-ichi Kogyo Seiyaku: F-10) at 50°C for 1 hour.

I, like B, is a comparison example, where 75% strong wheat flour is mixed with a three-type partially milled rice blend (black non-glutinous rice: extra-hard rice: koshihikari = 4:4:2) and 5% black rice glutinous rice bran is added as pregelatinized rice flour, which is then cooked and freeze-dried to create a 25% powder, and bread is made using tap water for the hydration during the bread making process.

As with B, J was made from 75% strong wheat flour and a pregelatinized rice flour containing 5% black rice bran added to a three-type partially milled rice blend (black non-glutinous rice: extra-hard rice: koshihikari = 4:4:2). The mixture was cooked and then freeze-dried, followed by the addition of 25% of the powder. For hydration during bread making, a rice bran extract was used, prepared by extracting red rice bran (0.05 g/mL) with a 0.5% aqueous solution of DK-ester (Dai-ichi Kogyo Seiyaku: F-10) at 50°C for 1 hour.

As with B, K was made from 75% strong wheat flour and, as pregelatinized rice flour, 5% black rice glutinous rice bran was added to a three-type rice blend (black non-glutinous rice: extra-hard rice: koshihikari = 4:4:2) of regular brown rice (not partially milled), which was then mixed and cooked and freeze-dried, followed by 25% freeze-dried powder. For hydration during bread making, a rice bran extract was used, prepared by extracting red rice non-glutinous rice bran (0.05 g/mL) with a 0.5% aqueous solution of DK-ester (Dai-ichi Kogyo Seiyaku: F-10) at 50°C for 1 hour.

Like B, L was made from 75% strong wheat flour, a three-type rice blend (black non-glutinous rice: extra-hard rice: koshihikari = 4:4:2) of germinated brown rice, with 5% black rice glutinous rice bran added, cooked together, and then 25% freeze-dried powder was added to make bread. For hydration during bread making, a rice bran extract was used, prepared by extracting red rice non-glutinous rice bran (0.05 g/mL) with a 0.5% aqueous solution of DK-ester (Dai-ichi Kogyo Seiyaku: F-10) at 50°C for 1 hour.

M, like B, is made from 75% strong wheat flour and 25% pregelatinized rice flour, which is made by adding 5% black rice glutinous rice bran to germinated large-germ rice, cooking it, freeze-drying it, and powdering it. The hydration used during bread making was a rice bran extract obtained by extracting red rice non-glutinous rice bran (0.05 g/mL) with a 0.5% aqueous solution of DK-ester (Dai-ichi Kogyo Seiyaku: F-10) at 50°C for 1 hour.

Figure 9 shows cross-sectional photographs of the various types of bread obtained through bread making.

The crumbs from each type of bread were then cut into squares measuring 1 cm thick and 2 cm on each side, and the "hardness," "firmness," "adhesion," "stickiness," "adhesion/hardness," and "stickiness/firmness" were measured using a Taketomo Electric Tensipresser.

The results are shown in Table 16. C, E, F, G, and M were soft, B and D were medium, A, I, and J were relatively hard, A, C, F, H, and M were very sticky and sticky, and B, D, G, and I were weakly sticky. In terms of the physical properties of the bread, the breads of the various examples of the present invention were comparable to the breads of the comparative examples A and B, and were shown to be fully edible.

Next, the above types of bread were stored at 6°C for 24 hours, and the physical properties after aging were measured using a tensipressor.

The results are shown in Table 17. Normally, bread hardness increases due to staling, but compared to comparative example B, all of the inventive examples except J showed a lower rate of increase in hardness than B, demonstrating that staling during storage was suppressed.

Furthermore, to examine the antioxidant properties of the various types of bread mentioned above, the ORAC values were measured. The results are shown in Table 18. Compared to Comparative Examples A and B, Examples C to G, I, and J all showed increased H-ORAC values, except for H, for the inventive examples C to J, with J to M showing particularly significant increases. The L-ORAC values for all samples, including sample H, were either the same as or increased compared to the comparative examples, with L and M showing significant increases.

This demonstrates that the antioxidant properties of bread made using black rice bran extract or red rice bran extract are significantly enhanced.

(Rice cooked with both rice bran extract and rice bran extract residue added)
Black non-glutinous rice, extra-hard rice, and regular rice (99% yield) were mixed in a weight ratio of 4:4:2 to make 450 g, and a total of 13.5 g of freeze-dried powder of black rice bran extract prepared in the same manner as in Example 13 and powder obtained by drying the extraction residue at 60°C for 6 hours were added. The mixture was packed and sealed in a pressure-resistant plastic tray, and subjected to high-pressure treatment at 200 MPa as in Example 15-E. After adding water to an amount 1.4 times the weight of the rice (dry matter), the rice was cooked. As a comparative example, cooked rice was prepared using 100% regular rice as the raw material, but without adding the bran extract or extraction residue, and subjected to high-pressure treatment and cooking. Photographs of both samples are shown in Figure 10, and the ingredients of both samples are listed in Table 19. Compared to the comparative example, the inventive example had higher protein and mineral content, approximately 30 times more dietary fiber, 10.6 mg/100 g of anthocyanins, which were not present at all in the comparative example, and approximately 14 times more gamma-aminobutyric acid (GABA), which has been reported to have a psychiatric stabilizing effect, than the comparative example. From these points, the inventive example was considered to be extremely promising in terms of its indigestibility and dementia prevention effect.

All values indicate the content percentage (%) per 100g of sample unless units are specified.

The physical properties of cooked rice were measured using a tensipresser after cooking and then storing at 25°C for 2 hours. The results are shown in Table 20. The inventive example was significantly harder and less sticky than the comparative example, and was expected to have an effect of suppressing postprandial blood glucose rise.

The results of measuring antioxidant activity (ORAC value) are shown in Table 21. Compared to the comparative example, the inventive example had significantly stronger water-soluble and fat-soluble antioxidant activity, suggesting a preventive effect against lifestyle-related diseases, particularly anti-dementia effects.

(Antioxidant properties of rice bran and freeze-dried rice bran extract)
Koshihikari, black rice, and extra-hard rice brown rice were milled to a 90% yield using a grinding rice mill to prepare bran. The extracts (5% bran by mass) extracted from each type of bran at 42°C for 17 hours with the addition of 0.5% sucrose fatty acid ester (Dai-ichi Kogyo Seiyaku: DK Ester F-160) were freeze-dried. The antioxidant activity of the extracts is shown in Table 22. The H-ORAC value, an indicator of water-soluble antioxidant activity, was 1.3 to 3.8 times higher for the 5% bran extract from Koshihikari and the 5% bran extract from extra-hard rice compared to the original bran, while the 5% bran extract from black rice glutinous rice showed a value slightly higher than the original bran. The L-ORAC value, an index of fat-soluble antioxidant activity, was 1.7 times higher for the 5% Koshihikari bran extract than for the original bran, while the 5% extra-hard rice bran extract showed a slightly lower value than for the original bran, and the 5% black rice glutinous bran extract showed a slightly higher value than for the original bran. All three types also showed higher total ORAC values than for the original bran.

(Example of a beverage made from rice bran extract)
As shown in Figure 3 of Example 8, the black rice bran extract exhibited a good wine red color. Based on this, various beverages were produced as prototypes.

As an example, cooked rice, a mixture of three types of rice (black rice, extra-hard rice, and Koshihikari rice) (4:4:2) prepared in the same manner as Sample No. 1 in Example 2, was freeze-dried using a Tokyo Rikakikai FD1000 freeze dryer, and the resulting dried material was powdered using a coffee mill and a cyclone mill to prepare a dried sample, which was then subjected to enzyme treatment in the following steps.

100 ml of pure water was added to 10 g of dried sample, and the pH was adjusted to 2 with 1N hydrochloric acid. 100 mg of pepsin (Sigma-Aldrich) was then added and the mixture was allowed to react at 37°C for 4 hours. Next, the pH was adjusted to 8 with 1N NaOH, and 100 mg of pancreatin (Sigma-Aldrich) was added. The mixture was then allowed to react at 37°C for 18 hours. Finally, the reaction was terminated by boiling at 100°C for 10 minutes, and the mixture was filtered through a filter cloth to obtain a clear rice beverage.

Unless otherwise stated, the black rice polyphenols give the beverage an astringent taste, but by adding 5% or more of mandarin orange juice, which is primarily fructose and has a weak effect on raising blood sugar after meals, the astringency of the beverage is suppressed, and the sweetness and aroma are increased, resulting in a rice beverage that is expected to have multiple functions, including the postprandial blood sugar raising effect of the black rice pigment polyphenols and antioxidant properties.

To improve the astringency, it was possible to use a variety of fruit juices, not just mandarin orange juice, such as apple juice, grape juice, and pineapple juice.

[summary]
Brown rice contains about 3% lipids, and the reported functionality of rice oil includes antioxidant properties, immune-stimulating properties, and cholesterol-lowering effects. "Koshihikari" had about 1.2 times more linoleic acid than other varieties. "Okunomurasaki" and "Super Hard Rice" also had about 1.1 times more oleic acid than other varieties, and "Black Glutinous Rice" had about 1.2 to 1.6 times more alpha-linolenic acid than other varieties, and it was expected that these combinations would improve functionality.

Based on the evaluation of the physicochemical properties and functionality of partially milled mixed cooked rice, further investigations were conducted to enhance the functionality of the mixed cooked rice. Specifically, when 0.5% DK-ester was added to black rice glutinous rice and extracted at 50°C, high anthocyanin content, ORAC value, and β-secretase inhibitory activity were observed. Furthermore, partially milled brown rice "Oku no Murasaki" cooked with this extract and mixed cooked rice also showed high anthocyanin content and ORAC value. However, a decrease in the physical properties of "adhesion" and "stickiness" was observed, making improvement of these physical properties an issue. However, it was found that by blending three types of raw rice and cooking using black rice bran extract as the cooking liquid, the appearance and stickiness of the cooked rice were improved, and cooked rice with significantly improved antioxidant capacity was obtained.

Furthermore, when the researchers investigated whether the β-secretase inhibitory activity was due to the pigment components of black rice and brown rice, anthocyanins, or rice lipids, they found that the 70% ethanol extract exhibited inhibitory activity 1.6 to 7.4 times higher than the hexane extract, demonstrating that the inhibitory activity was due to pigments such as anthocyanins.

In this invention, it was discovered that using pigmented rice bran extract in processes such as rice cooking, bread making, and noodle making can result in improved taste and health functionality. However, it was also discovered that adding pigmented rice bran extract residue also adds insoluble dietary fiber and high molecular weight polyphenols, resulting in processed products with even improved functionality, although the taste is slightly inferior.

Since the Ministry of Agriculture, Forestry and Fisheries launched the New Trait Rice Project in 1989, a variety of new trait rice varieties with different shapes and characteristics have been developed, including high-amylose rice, low-amylose rice, giant germ rice, fragrant rice, and pigmented rice.

Rice bran also contains various functional ingredients such as dietary fiber, vitamin E, and gamma-oryzanol, and is also high in lipids, so rice bran and brown rice have been considered effective in maintaining and improving health functions.

Japan is currently facing an ultra-aging society, with lifestyle-related diseases such as diabetes, high blood pressure, and kidney disease on the rise, and national medical expenses exceeding 40 trillion yen per year. Furthermore, as the aging population progresses, the number of dementia patients, particularly Alzheimer's disease, is also increasing, and in addition to the development of treatments and drugs for lifestyle-related diseases and dementia, there are high hopes for dietary prevention.

Against the above background, this invention focuses on new trait rice that is expected to have functional properties, particularly pigmented rice such as black rice and red rice, and extra-hard rice. By adding pigmented rice bran extract to brown rice or processed brown rice products and cooking or processing them, we provide a technology for producing cooked rice or processed rice foods that have the combined functions of preventing diabetes by suppressing postprandial blood glucose increases, and preventing the onset of dementia by providing antioxidant properties and inhibiting β-secretase activity.

By putting this technology into practical use, it will be possible to develop cooked rice and processed rice foods that are expected to have the combined effect of preventing diabetes and dementia, and it is hoped that food will help maintain and improve health.

Claims (13)

This method for producing functional processed rice foods comprises an extraction step in which components contained in the rice bran of pigmented rice are extracted with an aqueous solution of sucrose fatty acid ester to obtain an extract, and a processing step in which the extract obtained by this extraction step is used to obtain a processed rice food. The method for producing a functional processed rice food according to claim 1, characterized in that the pigmented rice is black rice or red rice. The method for producing a functional processed rice food according to claim 1 or 2, characterized in that the processed rice food is cooked rice, and the raw rice for the cooked rice is black rice and/or extra-hard rice. The method for producing a functional processed rice food according to claim 1 or 2, characterized in that the processed rice food is one of cooked rice, bread, noodles, confectionery, and beverages. The method for producing a functional rice processed food according to claim 4, characterized in that the raw rice used in the processed rice food is brown rice, partially milled brown rice, or germinated brown rice. 6. The method for producing the functional processed rice food according to any one of claims 1 to 5, characterized in that in the extraction step, rice bran obtained by polishing black rice or red rice to a polishing yield of 85 to 99% by mass is added to an aqueous sucrose fatty acid ester solution having an HLB of 3 to 16 in a ratio of 1 to 20% by mass, and the solution is soaked at a temperature of 30 to 80°C for 10 minutes to 24 hours, after which solid matter is removed to obtain the extract. 6. The method for producing a functional processed rice food according to any one of claims 1 to 5, characterized in that in the extraction step, rice bran obtained by polishing waxy black rice or waxy red rice to a polishing yield of 85 to 95% by mass is added to an aqueous sucrose fatty acid ester solution having an HLB of 6 to 13 in a proportion of 5 to 20% by mass, and the solution is soaked at a temperature of 40 to 60°C for 30 minutes to 18 hours, after which solid matter is removed to obtain the extract, and in the processing step, 100 to 2000% by mass of the extract is added to raw rice blended with 20% or more by mass of pigmented brown rice or a processed brown rice product, and extra-hard brown rice or a processed brown rice product, and the resulting mixture is cooked. 6. The method for producing a functional processed rice food according to any one of claims 1 to 5, characterized in that in the extraction step, rice bran obtained by polishing waxy black rice or waxy red rice to a polishing yield of 85 to 95% by mass is added to an aqueous sucrose fatty acid ester solution having an HLB of 6 to 13 in a ratio of 5 to 20% by mass, and the solution is soaked at a temperature of 40 to 60°C for 30 minutes to 18 hours, after which solid matter is removed to obtain an extract, and in the processing step, the processed rice food is obtained using the extract and raw material rice blended with 20% or more by mass of pigmented brown rice or a processed brown rice product, and 20 % or more by mass of extra-hard brown rice or a processed brown rice product. 6. The method for producing a functional processed rice food according to any one of claims 1 to 5, characterized in that in the extraction step, rice bran obtained by polishing black rice or red rice to a polishing yield of 85 to 99% by mass is added to an aqueous sucrose fatty acid ester solution having an HLB of 3 to 16 in a proportion of 1 to 20% by mass, and the solution is soaked at a temperature of 30 to 80°C for 10 minutes to 24 hours, and then solid matter is removed to obtain the extract; and in the processing step, 100 to 2000% by mass of the extract is added to raw rice blended with 5 to 60% by mass of pigmented brown rice or a processed brown rice product, and the resulting mixture is subjected to a high-pressure treatment at 200 MPa or more, followed by cooking. 6. The method for producing a functional processed rice food according to any one of claims 1 to 5, wherein in the extraction step, rice bran obtained by polishing waxy black rice and/or waxy red rice to a polishing yield of 85 to 95% by mass is added to an aqueous sucrose fatty acid ester solution having an HLB of 6 to 13 in a ratio of 5 to 20% by mass, and the solution is soaked at a temperature of 40 to 60°C for 30 minutes to 24 hours, and then the extract and solid matter are obtained by filtration and/or centrifugation, and in the processing step, the processed rice food is obtained using raw material rice blended with pigmented brown rice and/or processed brown rice products and extra-hard brown rice and/or processed brown rice products in proportions of 20% by mass or more each, the extract, and the solid matter. 6. The method for producing the functional processed rice food according to any one of claims 1 to 5, characterized in that in the extraction step, rice bran obtained by polishing black rice or red rice to a polishing yield of 85 to 99% by mass is added to an aqueous sucrose fatty acid ester solution having an HLB of 3 to 16 in a proportion of 1 to 20% by mass, and the solution is soaked at a temperature of 30 to 80°C for 10 minutes to 24 hours, and the solid matter is separated to obtain the extract and the solid matter; and in the processing step, 100 to 2000% by mass of the extract and 0.5 to 10% by mass of the solid matter are added to raw rice blended with pigmented rice in a proportion of 5% to 60% by mass, and the mixture is subjected to a high-pressure treatment of 200 MPa or more, followed by cooking. The method for producing a functional processed rice food according to any one of claims 1 to 11 , characterized in that pigmented rice with a milling yield of 95% or more is used in the processing step. 13. The method for producing a functional processed rice food according to any one of claims 1 to 12 , wherein the processed rice food obtained in the processing step has a function of suppressing postprandial blood glucose elevation due to its indigestibility, antioxidant properties, and a function of preventing dementia due to its β-secretase inhibitory activity.