Modifier for cooked rice, method for modifying cooked rice, and method for producing cooked rice

Abstract

The purpose of the present invention is to provide a technique capable of achieving a modification of cooked rice suitable for an intended use of the cooked rice.　Provided is a modifier for cooked rice, the modifier comprising at least one enzyme selected from cyclodextrin-producing enzymes, lipases, cellulases, hemicellulases, proteases, α-glucosidase, maltotriose-producing enzymes, and α-amylase or a cyclodextrin-producing enzyme and 4-α-glucanotransferase. The modifier for cooked rice according to the present technology can modify at least one quality of cooked rice, wherein the quality is selected from flavor, a property of being loosened, fluffy and granular appearance, sweetness, hardness, softness, and stickiness.

Description

Cooked rice modifier, cooked rice modifier method, and cooked rice manufacturing method

[0001] The present technology relates to a modifier for cooked rice. More specifically, the present technology relates to a modifier for cooked rice that uses a specific enzyme, a method for modifying cooked rice, and a method for producing cooked rice.

[0002] In the food and beverage industry, technologies for improving the quality of food and beverage products using various enzymes have been developed. For example, Patent Document 1 proposes a technology for producing noodles that maintain the original appearance, shape, and flavor of the noodles and are soft enough to be crushed with the tongue and easy to swallow, by carrying out a step of placing noodles in a liquid in a tank, evacuating the container, and a step of heat-treating the noodles in a saturated steam pressure environment. The technology also proposes a further enzyme treatment step to reduce stickiness on the surface of the noodles, making them easier to eat.

[0003] Furthermore, for example, Patent Document 2 proposes a technique for maintaining the texture of cooked rice made from glutinous rice by using β-amylase, citric acid and / or a salt thereof, and a monoglycerin fatty acid ester in combination.

[0004] JP 2020-110146 A JP 2018-113872 A

[0005] As mentioned above, technologies for improving the quality of food and beverages are being developed. Among food and beverages, cooked rice, obtained by cooking rice, is used for a wide variety of purposes, such as being eaten as is, processed into rice balls, rice bowls, fried rice, etc., or frozen for long-term storage, and therefore there is a need for quality improvements suitable for each purpose.

[0006] Therefore, the main objective of this technology is to provide a technology that can modify cooked rice to suit its intended use.

[0007] The present technology first provides a cooked rice improver containing one or more enzymes selected from a cyclodextrin-forming enzyme, lipase, cellulase, hemicellulase, protease, α-glucosidase, maltotriose-forming enzyme, and α-amylase, or a cyclodextrin-forming enzyme and 4-α-glucanotransferase. The cooked rice improver according to the present technology can improve one or more qualities of cooked rice selected from aroma, loosening ability, graininess, sweetness, hardness, softness, and stickiness.

[0008] The present technology next provides a cooked rice modification method including an enzyme addition step of adding one or more enzymes selected from a cyclodextrin-forming enzyme, lipase, cellulase, hemicellulase, protease, α-glucosidase, maltotriose-forming enzyme, and α-amylase, or a cyclodextrin-forming enzyme and 4-α-glucanotransferase to rice.The present technology also provides a cooked rice modification method including a rice cooking step of cooking rice to which one or more enzymes selected from a cyclodextrin-forming enzyme, lipase, cellulase, hemicellulase, protease, α-glucosidase, maltotriose-forming enzyme, and α-amylase, or a cyclodextrin-forming enzyme and 4-α-glucanotransferase have been added. The cooked rice modification method according to the present technology can modify the quality of one or more cooked rice selected from aroma, loosening property, graininess, sweetness, hardness, softness, and stickiness.

[0009] The present technology further provides a method for producing cooked rice, which includes a rice cooking step of cooking rice to which a cyclodextrin-forming enzyme has been added. In this case, the rice may be rice to which a 4-α-glucanotransferase has been added.

[0010] Preferred embodiments for carrying out the present technology will be described below. Note that the embodiments described below are examples of typical embodiments of the present technology, and the scope of the present technology should not be construed as being narrow.

[0011] 1. Cooked rice modifier The cooked rice modifier according to the present technology contains one or more enzymes selected from cyclodextrin-forming enzymes, lipases, cellulases, hemicellulases, proteases, α-glucosidases, maltotriose-forming enzymes, and α-amylases, or contains cyclodextrin-forming enzymes and 4-α-glucanotransferases. Other enzymes and other components may also be included as needed. Each component that can be used in the present technology will be described in detail below.

[0012] (1) Cyclodextrin-forming enzyme The cyclodextrin-forming enzyme (EC 2.4.1.19) that can be used in the present technology is an enzyme that has the activity of producing cyclodextrin having a degree of polymerization of 6 to 8 using a polymer composed of α-1,4-linked glucose, such as starch, as a substrate. The cyclodextrin-forming enzyme that can be used in the present technology may also be an enzyme that has other functions as long as it has the activity of producing cyclodextrin.

[0013] In this technology, by producing cooked rice using a cyclodextrin-producing enzyme, the effects of retaining the aroma of cooked rice, improving loosening properties, and increasing stickiness can be achieved. Furthermore, producing cooked rice using a cyclodextrin-producing enzyme also has the effect of inhibiting the aging of cooked rice, so cooked rice produced using the cyclodextrin-producing enzyme can maintain the aroma retention effect, the loosening property improvement effect, and the stickiness increase effect even after storage. Furthermore, cooked rice produced using the cyclodextrin-producing enzyme can also enhance the sweetness of cooked rice by storing it for a predetermined period of time. In addition, cooked rice produced using the cyclodextrin-producing enzyme can also be expected to have a high dietary fiber content.

[0014] The origin of the cyclodextrin-forming enzyme that can be used in the present technology is not particularly limited. For example, the genus Bacillus includes Bacillus stearothermophilus, Bacillus megaterium, Bacillus circulans, Bacillus macerans, Bacillus ohbensis, and Bacillus clarkii; the genus Geobacillus includes Geobacillus stearothermophilus; the genus Paenibacillus includes Paenibacillus Examples of the genus Klebsiella include Klebsiella pneumoniae; examples of the genus Anoxybacillus include Anoxybacillus caldiproteolyticus, Anoxybacillus pushchinoensis, and Anoxybacillus flavithermus; and cyclodextrin-forming enzymes derived from microorganisms of the genera Thermoanaerobacter and Brevibacterium. These cyclodextrin-forming enzymes may be used alone or in combination. In particular, from the viewpoint of the effect of improving the quality of cooked rice, the cyclodextrin-forming enzyme is preferably a cyclodextrin glucanotransferase derived from a microorganism of the genus Anoxybacillus. In the present technology, Anoxybacillus caldiproteolyticus (including the one formerly known as Geobacillus stearothermophilus) is used.It is more preferable that the cyclodextrin glucanotransferase is derived from Bacillus subtilis.

[0015] Here, "cyclodextrin-forming enzyme derived from Anoxybacillus caldiproteolyticus" means a cyclodextrin-forming enzyme produced by a microorganism classified as Anoxybacillus caldiproteolyticus (whether a wild-type strain or a mutant strain), or a cyclodextrin-forming enzyme obtained by genetic engineering techniques using a cyclodextrin-forming enzyme gene. Therefore, a recombinant produced by a host microorganism into which a cyclodextrin-forming enzyme gene obtained from Anoxybacillus caldiproteolyticus (or a modified version of said gene) has been introduced also falls under the category of "cyclodextrin-forming enzyme derived from Anoxybacillus caldiproteolyticus."

[0016] The cyclodextrin-forming enzyme used in the present technology can be prepared from the culture medium of the microorganism from which the cyclodextrin-forming enzyme is derived. Specific preparation methods include methods in which the cyclodextrin-forming enzyme is recovered from the culture medium or cells of the microorganism. For example, when a cyclodextrin-forming enzyme-secreting microorganism is used, the cells can be recovered from the culture medium in advance by filtration, centrifugation, or the like, as necessary, and the enzyme can then be separated and / or purified. Furthermore, when a cyclodextrin-forming enzyme-nonsecreting microorganism is used, the cells can be recovered from the culture medium in advance by pressure treatment, ultrasonic treatment, or the like, and the enzyme can then be extracted and / or separated and / or purified. The enzyme separation and / or purification method can be any known protein separation and / or purification method, without any particular limitation, and examples thereof include centrifugation, UF concentration, salting out, and various chromatography methods using ion exchange resins, etc. The isolated and / or purified enzyme can be powdered by a drying method such as freeze-drying or vacuum drying, or can be powdered using an appropriate excipient and / or drying aid in the drying method. The isolated and / or purified enzyme can also be liquefied by adding an appropriate additive and sterilizing by filtration.

[0017] In the present technology, commercially available cyclodextrin-producing enzymes can also be used, and a preferred example of a commercially available product is cyclodextrin glucanotransferase derived from Anoxybacillus caldiproteolyticus (Geobacillus stearothermophilus) manufactured by Amano Enzyme Inc.

[0018] The content of the cyclodextrin-forming enzyme in the cooked rice modifying agent according to the present technology can be freely set as long as it does not impair the effects of the present technology. The content of the cyclodextrin-forming enzyme can be set to, for example, 0.002 U or more per gram of raw rice used to produce cooked rice, and from the viewpoint of further enhancing the cooked rice modifying effect, the content can be set to preferably 0.01 U or more, more preferably 0.02 U or more, even more preferably 0.2 U or more, and even more preferably 0.35 U or more.

[0019] The upper limit of the amount of cyclodextrin-forming enzyme contained is not particularly limited as long as it does not impair the effects of the present technology, and can be set to, for example, 400 U or less, 300 U or less, 200 U or less, 100 U or less, 80 U or less, 60 U or less, 40 U or less, 20 U or less, 10 U or less, 5 U or less, 1 U or less, 0.8 U or less, 0.6 U or less, 0.5 U or less, or 0.45 U or less per gram of raw rice used to produce cooked rice.

[0020] In the present technology, the activity of the cyclodextrin-forming enzyme is a value measured by the measurement method described in the Examples below.

[0021] (2) Lipase The lipase that can be used in the present technology is an enzyme that has the activity of hydrolyzing triglycerides to produce diglycerides, monoglycerides, and fatty acids. The lipase that can be used in the present technology may also be an enzyme that has other functions as long as it has the activity of hydrolyzing triglycerides to produce diglycerides, monoglycerides, and fatty acids.

[0022] In this technology, by producing cooked rice using lipase, it is possible to achieve the effects of enhancing the sweetness, softness, loosening, graininess, and stickiness of cooked rice. Generally, when the stickiness of cooked rice is improved, the loosening and graininess deteriorate. However, this technology has discovered that by adding lipase, cooked rice can be obtained that combines the contradictory properties of graininess and stickiness. Furthermore, producing cooked rice using lipase also has the effect of inhibiting the aging of cooked rice, so cooked rice produced using lipase can retain the effects of enhancing the sweetness, softness, loosening, graininess, and stickiness even after storage.

[0023] The origin of the lipase that can be used in the present technology is not particularly limited, but examples include lipases derived from microorganisms of the genus Aspergillus, Candida, Rhizopus, Mucor, and Penicillium. These lipases may be used alone or in combination. Among these lipases, it is preferable to select a lipase derived from the genus Penicillium, and it is more preferable to select a lipase derived from Rhizopus oryzae, from the viewpoint of further enhancing the cooked rice improving effect.

[0024] Here, "lipase derived from Rhizopus oryzae" means a lipase produced by a microorganism classified as Rhizopus oryzae (whether a wild-type strain or a mutant strain), or a lipase obtained by genetic engineering techniques using a lipase gene. Therefore, a recombinant produced by a host microorganism into which a lipase gene obtained from Rhizopus oryzae (or a gene obtained by modifying said gene) has been introduced also falls under the category of "lipase derived from Rhizopus oryzae."

[0025] The lipase used in the present technology can be prepared from a culture solution of a microorganism from which the lipase is derived. Specific preparation methods include recovering the lipase from the culture solution or cells of the microorganism. For example, when a lipase-secreting microorganism is used, the cells can be recovered from the culture solution, if necessary, by filtration, centrifugation, or the like, and the enzyme can then be separated and / or purified. When a lipase-nonsecreting microorganism is used, the cells can be recovered from the culture solution, if necessary, and then disrupted by pressure treatment, ultrasonication, or the like to extract the enzyme, after which the enzyme can be separated and / or purified. The enzyme separation and / or purification method can be any known protein separation and / or purification method, without any particular limitation. Examples include centrifugation, UF concentration, salting out, and various chromatography methods using ion exchange resins. The separated and / or purified enzyme can be powdered by drying methods such as lyophilization and vacuum drying, or by using appropriate excipients and / or drying aids in the drying methods. The isolated and / or purified enzyme can also be liquefied by adding an appropriate additive and sterilizing by filtration.

[0026] In the present technology, commercially available lipases can also be used, and a preferred example of a commercially available lipase is lipase derived from Rhizopus oryzae manufactured by Amano Enzyme Inc.

[0027] The lipase content in the cooked rice modifier according to the present technology can be freely set as long as it does not impair the effects of the present technology. The lipase content can be set to, for example, 0.00075 U or more per gram of raw rice used to produce cooked rice, and from the viewpoint of further enhancing the cooked rice modifying effect, it can be set to preferably 0.0037 U or more, more preferably 0.0075 U or more, even more preferably 0.075 U or more, and even more preferably 0.13 U or more.

[0028] The upper limit of the lipase content is not particularly limited as long as it does not impair the effects of the present technology, but can be set to, for example, 150 U or less, 130 U or less, 110 U or less, 100 U or less, 90 U or less, 70 U or less, 50 U or less, 30 U or less, 15 U or less, 10 U or less, 5 U or less, 1 U or less, 0.5 U or less, 0.3 U or less, 0.2 U or less, or 0.17 U or less per 1 g of raw rice used to produce cooked rice.

[0029] In the present technology, the lipase activity is a value measured by the measurement method described in the Examples below.

[0030] (3) Cellulase The cellulase that can be used in the present technology is an enzyme that hydrolyzes the glycosidic bond of β-1,4-glucan (e.g., cellulose). The cellulase that can be used in the present technology may also have other functions as long as it has cellulase activity.

[0031] In this technology, by producing cooked rice using cellulase, it is possible to achieve the effect of improving the hardness and graininess of the cooked rice. In other words, by producing cooked rice using cellulase, it is possible to obtain hard cooked rice with a good graininess. Furthermore, by storing cooked rice produced using cellulase for a predetermined period of time, it is possible to achieve the effect of enhancing the sweetness of the cooked rice.

[0032] The origin of cellulase that can be used in the present technology is not particularly limited, and examples thereof include basidiomycetes such as the genus Corticium, the genus Irpex, and Pycnoporus coccineus, and filamentous fungi such as Acremonium cellulolyticus, Aspergillus aculeatus, Aspergillus oryzae, Aspergillus sojae, Aspergillus saitoi, Aspergillus flavus, Aspergillus awamori, Aspergillus niger, Humicola insolens, and Penicillium funiculosum. Examples of cellulases that can be used include cellulases derived from Trichoderma funiculosum, Trichoderma harzianum, Trichoderma insolens, Trichoderma koningii, Trichoderma longibrachiatum, Trichoderma reesei, and Trichoderma viride; actinomycetes from the genus Actinomyces and Streptomyces; and bacteria from Bacillus circulans and Bacillus subtilis. Preferably, cellulases are derived from microorganisms of the genus Trichoderma. Examples of microorganisms of the genus Trichoderma include Trichoderma reesei and Trichoderma viride.These cellulases may be used alone or in combination. Among these cellulases, from the viewpoint of further enhancing the cooked rice improving effect, it is preferable to select a cellulase derived from a microorganism of the genus Trichoderma, and it is more preferable to select a cellulase derived from Trichoderma viride.

[0033] Here, "cellulase derived from Trichoderma viride" means cellulase produced by a microorganism classified as Trichoderma viride (whether a wild-type strain or a mutant strain), or cellulase obtained by genetic engineering techniques using a cellulase gene. Therefore, a recombinant produced by a host microorganism into which a cellulase gene obtained from Trichoderma viride (or a gene obtained by modifying said gene) has been introduced also falls under the category of "cellulase derived from Trichoderma viride."

[0034] The cellulase used in this technology can be prepared from the culture medium of the microorganism from which the cellulase is derived. Specific preparation methods include recovering cellulase from the culture medium or cells of the microorganism. For example, when using a cellulase-secreting microorganism, the cells can be recovered from the culture medium in advance by filtration, centrifugation, or the like, as necessary, and the enzyme can then be separated and / or purified. When using a non-cellulase-secreting microorganism, the cells can be recovered from the culture medium in advance by pressure treatment, ultrasonic treatment, or the like, and the enzyme can then be extracted and / or separated and / or purified. The enzyme can be separated and / or purified using any known protein separation and / or purification method, without any particular limitation. Examples of the enzyme separation and / or purification method include centrifugation, UF concentration, salting out, and various chromatography methods using ion exchange resins. The separated and / or purified enzyme can be powdered by drying methods such as freeze-drying and vacuum drying, and can also be powdered using appropriate excipients and / or drying aids in the drying methods. The isolated and / or purified enzyme can also be liquefied by adding an appropriate additive and sterilizing by filtration.

[0035] In the present technology, commercially available cellulases can also be used, and a preferred example of a commercially available cellulase is cellulase derived from a microorganism of the genus Trichoderma manufactured by Amano Enzyme Inc.

[0036] The content of cellulase in the cooked rice modifier according to the present technology can be freely set as long as it does not impair the effects of the present technology. The content of cellulase can be set to, for example, 0.0014 U or more per 1 g of raw rice used to produce cooked rice, and from the viewpoint of further enhancing the cooked rice modifying effect, it can be set to preferably 0.007 U or more, more preferably 0.014 U or more, even more preferably 0.07 U or more, 0.14 U or more, and even more preferably 0.25 U or more.

[0037] The upper limit of the cellulase content is not particularly limited as long as it does not impair the effects of the present technology, but can be set to, for example, 280 U or less, 250 U or less, 230 U or less, 200 U or less, 150 U or less, 130 U or less, 100 U or less, 90 U or less, 70 U or less, 60 U or less, 56 U or less, 50 U or less, 30 U or less, 28 U or less, 25 U or less, 23 U or less, 20 U or less, 10 U or less, 5 U or less, 3 U or less, 1 U or less, 0.56 U or less, 0.42 U or less, or 0.31 U or less per 1 g of raw rice used to produce cooked rice.

[0038] In the present technology, the cellulase activity is a value measured by the measurement method described in the Examples below.

[0039] (4) Hemicellulase The hemicellulase that can be used in the present technology is an enzyme that hydrolyzes hemicellulose. Hemicellulose is a heteropolysaccharide composed of multiple constituent sugars and generally has a branched structure in which other constituent sugars form side chains on the main chain from which the name is derived. Specific examples of hemicellulose include mannan, β-1,3-1,4-glucan, glucomannan, xylan, xyloglucan, and glucuronoxylan. Hemicellulase is an enzyme that decomposes these hemicelluloses.

[0040] In this technology, by producing cooked rice using hemicellulase, it is possible to achieve the effects of improving the graininess, softness, and stickiness of cooked rice. Generally, when the stickiness and softness of cooked rice are improved, the graininess decreases. However, this technology has discovered that by adding hemicellulase, cooked rice can be produced that combines the contradictory properties of graininess and stickiness and softness. Furthermore, producing cooked rice using hemicellulase also has the effect of inhibiting the aging of cooked rice, so cooked rice produced using hemicellulase can maintain the effects of improving softness and stickiness even after storage. Furthermore, producing cooked rice using hemicellulase can produce cooked rice with enhanced sweetness.

[0041] Specific examples of hemicellulases include xylanase, galactanase, mannanase, galactomannanase, arabinase, β-glucanase, etc., and these may be used alone or in combination of two or more.

[0042] The origin of the hemicellulase is not particularly limited, and may be hemicellulase derived from microorganisms such as basidiomycetes such as Corticium and Pycnoporus, filamentous fungi such as Aspergillus, Humicola, Penicillium, and Trichoderma, actinomycetes such as Streptomyces, or bacteria such as Bacillus, or may be artificially synthesized hemicellulase. These may be used alone or in combination of two or more. Among these, in the present technology, hemicellulase derived from filamentous fungi is preferred, hemicellulase derived from microorganisms of the genus Aspergillus is more preferred, and hemicellulase derived from Aspergillus niger is even more preferred.

[0043] Here, "hemicellulase derived from Aspergillus niger" means hemicellulase produced by a microorganism classified as Aspergillus niger (whether a wild-type strain or a mutant strain), or hemicellulase obtained by genetic engineering techniques using a hemicellulase gene. Therefore, a recombinant produced by a host microorganism into which a hemicellulase gene obtained from Aspergillus niger (or a gene obtained by modifying said gene) has been introduced also falls under the category of "hemicellulase derived from Aspergillus niger."

[0044] The hemicellulase used in the present technology can be prepared from the culture medium of the microorganism from which the hemicellulase is derived. Specific preparation methods include recovering hemicellulase from the culture medium or cells of the microorganism. For example, when using a hemicellulase-secreting microorganism, the cells can be recovered from the culture medium by filtration, centrifugation, or the like, as necessary, and the enzyme can then be separated and / or purified. When using a non-hemicellulase-secreting microorganism, the cells can be recovered from the culture medium by, as necessary, pre-disruption by pressure treatment, ultrasonication, or the like to extract the enzyme, and the enzyme can then be separated and / or purified. The enzyme can be separated and / or purified by any known protein separation and / or purification method, without any particular limitation. Examples of the enzyme separation and / or purification method include centrifugation, UF concentration, salting out, and various chromatography methods using ion exchange resins. The separated and / or purified enzyme can be powdered by drying methods such as freeze-drying and vacuum drying, or by using appropriate excipients and / or drying aids in the drying methods. The isolated and / or purified enzyme can also be liquefied by adding an appropriate additive and sterilizing by filtration.

[0045] In the present technology, commercially available hemicellulase can also be used, and a preferred example of a commercially available hemicellulase is hemicellulase derived from Aspergillus microorganisms manufactured by Amano Enzyme Inc.

[0046] The content of hemicellulase in the cooked rice modifying agent according to the present technology can be freely set as long as it does not impair the effects of the present technology. The content of hemicellulase can be set to, for example, 0.45 U or more per 1 g of raw rice used to produce cooked rice, and from the viewpoint of further enhancing the cooked rice modifying effect, the content can be set to preferably 2.25 U or more, more preferably 4.5 U or more, 5 U or more, 7 U or more, 9 U or more, 10 U or more, 20 U or more, 30 U or more, 40 U or more, even more preferably 45 U or more, 60 U or more, and even more preferably 81 U or more.

[0047] The upper limit of the hemicellulase content is not particularly limited as long as it does not impair the effects of the present technology, but can be set to, for example, 90,000 U or less, 70,000 U or less, 50,000 U or less, 30,000 U or less, 20,000 U or less, 18,000 U or less, 15,000 U or less, 13,000 U or less, 10,000 U or less, 9,000 U or less, 7,000 U or less, 5,000 U or less, 3,000 U or less, 1,000 U or less, 800 U or less, 600 U or less, 400 U or less, 200 U or less, 180 U or less, 135 U or less, 110 U or less, or 99 U or less per 1 g of raw rice used to produce cooked rice.

[0048] In the present technology, the hemicellulase activity is a value measured by the measurement method described in the Examples below.

[0049] (5) Protease The protease that can be used in the present technology is an enzyme that catalyzes the hydrolysis of peptide bonds. The protease that can be used in the present technology may also have other functions as long as it has protease activity.

[0050] In this technology, the use of proteases in the production of cooked rice can improve the softness and viscosity of cooked rice. Furthermore, the use of proteases in the production of cooked rice also has the effect of inhibiting the aging of cooked rice, so cooked rice produced using proteases can maintain its softness and viscosity even after storage. Furthermore, it has been found that the use of proteases in the production of cooked rice reduces the aroma and sweetness characteristic of cooked rice. In other words, it has been found that the use of proteases in the production of cooked rice can modify the flavor of cooked rice. This flavor modification effect can be maintained even after storage. By reducing the aroma and sweetness characteristic of cooked rice, the impact on other seasonings and aromas can be reduced, making it possible to anticipate applications in a variety of applications.

[0051] The origin of the protease that can be used in the present technology is not particularly limited. For example, proteases derived from filamentous fungi are not particularly limited, and examples thereof include proteases derived from the genera Aspergillus, Rhizopus, Mucor, Neurospora, Penicillium, Rhizomucor, and Sclerotinia. Specific examples of proteases derived from the genus Aspergillus include Aspergillus oryzae, Aspergillus niger, Aspergillus melleus, Aspergillus japonicus, Aspergillus awamori, Aspergillus kawachii, Aspergillus sojae, Aspergillus tamarii, Aspergillus foetidus, Aspergillus fumigatus, Aspergillus nidulans, and Aspergillus aculetus. aculeatus, Aspergillus candidus, Aspergillus flavus, Aspergillus saitoi, Aspergillus inuii, Aspergillus glaucus, Aspergillus caesiellus, Aspergillus clavatus, Aspergillus deflectus, Aspergillus fischarianusSpecific examples of proteases derived from the genus Rhizopus include proteases derived from Rhizopus chinensis, Rhizopus delemar, Rhizopus niveus, and Rhizopus oryzae. Examples of bacterial proteases include proteases derived from the genus Bacillus and Geobacillus. Specific examples of proteases derived from the genus Bacillus (or Geobacillus) include proteases derived from Bacillus amyloliquefaciens, Bacillus cereus, Bacillus clausii, Bacillus intermedius, Bacillus lentus, Bacillus licheniformis, Bacillus stearothermophilus, Bacillus subtilis, and Bacillus thermoproteolyticus.Examples of proteases include proteases derived from the genus Geobacillus (Geobacillus thermoproteolyticus), and proteases derived from these genus Geobacillus. These proteases may be used singly or in combination of two or more. Among these proteases, from the viewpoint of further enhancing the cooked rice improving effect, it is preferable to select a protease derived from a microorganism of the genus Bacillus, and it is more preferable to select a protease derived from Bacillus amyloliquefaciens.

[0052] Here, "protease derived from Bacillus amyloliquefaciens" means a protease produced by a microorganism classified as Bacillus amyloliquefaciens (whether a wild-type strain or a mutant strain), or a protease obtained by genetic engineering techniques using a protease gene. Therefore, a recombinant produced by a host microorganism into which a protease gene obtained from a Bacillus amyloliquefaciens organism (or a gene obtained by modifying said gene) has been introduced also falls under the category of "protease derived from Bacillus amyloliquefaciens."

[0053] The protease used in the present technology can be prepared from the culture medium of the microorganism from which the protease is derived. Specific preparation methods include recovering the protease from the culture medium or cells of the microorganism. For example, when a protease-secreting microorganism is used, the cells can be recovered from the culture medium by filtration, centrifugation, or the like, as necessary, and the enzyme can then be separated and / or purified. When a protease-nonsecreting microorganism is used, the cells can be recovered from the culture medium by, as necessary, pre-disruption by pressure treatment, ultrasonication, or the like to extract the enzyme, and the enzyme can then be separated and / or purified. The enzyme separation and / or purification method can be any known protein separation and / or purification method, without any particular limitation. Examples include centrifugation, UF concentration, salting out, and various chromatography methods using ion exchange resins. The separated and / or purified enzyme can be powdered by drying methods such as lyophilization and vacuum drying, or by using appropriate excipients and / or drying aids in the drying methods. The isolated and / or purified enzyme can also be liquefied by adding an appropriate additive and sterilizing by filtration.

[0054] In the present technology, commercially available proteases can also be used, and a preferred example of a commercially available protease is a protease derived from a microorganism of the genus Bacillus manufactured by Amano Enzyme Inc.

[0055] The protease content in the cooked rice modifier according to the present technology can be freely set as long as it does not impair the effects of the present technology. The protease content can be set to, for example, 0.35 U or more per gram of raw rice used to produce cooked rice, and from the viewpoint of further enhancing the cooked rice modifying effect, it can be set to preferably 1.75 U or more, more preferably 3.5 U or more, 4 U or more, 6 U or more, 8 U or more, 10 U or more, 20 U or more, 30 U or more, even more preferably 35 U or more, 50 U or more, 60 U or more, and even more preferably 63 U or more.

[0056] The upper limit of the protease content is not particularly limited as long as it does not impair the effects of the present technology, and can be set to, for example, 70,000 U or less, 50,000 U or less, 30,000 U or less, 20,000 U or less, 14,000 U or less, 12,000 U or less, 10,000 U or less, 9,000 U or less, 7,000 U or less, 5,000 U or less, 3,000 U or less, 1,000 U or less, 900 U or less, 700 U or less, 500 U or less, 300 U or less, 200 U or less, 140 U or less, 105 U or less, 90 U or less, 80 U or less, or 77 U or less per 1 g of raw rice used to produce cooked rice.

[0057] In the present technology, the protease activity is a value measured by the measurement method described in the Examples below.

[0058] (6) α-Glucosidase The α-glucosidase that can be used in the present technology is an enzyme that catalyzes the hydrolysis of α-1,4-glucosidic bonds. The α-glucosidase that can be used in the present technology may also have other functions as long as it has α-glucosidase activity.

[0059] In this technology, by producing cooked rice using α-glucosidase, it is possible to achieve the effects of preserving the aroma of cooked rice, enhancing sweetness, improving softness, and increasing stickiness. Furthermore, producing cooked rice using α-glucosidase also has the effect of inhibiting the aging of cooked rice, so cooked rice produced using α-glucosidase can maintain its effects of enhancing sweetness, softness, and stickiness even after storage. Furthermore, cooked rice produced using α-glucosidase can also achieve the effect of improving the graininess by storing it for a predetermined period of time.

[0060] The origin of the α-glucosidase that can be used in the present technology is not particularly limited, but examples include α-glucosidases derived from plants (rice, millet, green onion, mung bean, buckwheat, etc.), and α-glucosidases derived from microorganisms such as Aspergillus genus filamentous fungi, Saccharomyces genus yeasts, and Bacillus genus bacteria. These α-glucosidases may be used alone or in combination. Among these α-glucosidases, it is preferable to select α-glucosidases derived from microorganisms of the genus Apergillus in order to further enhance the cooked rice improving effect.

[0061] Here, "α-glucosidase derived from a microorganism of the genus Aspergillus" means an α-glucosidase produced by a microorganism classified into the genus Aspergillus (whether a wild-type strain or a mutant strain), or an α-glucosidase obtained by genetic engineering techniques using an α-glucosidase gene. Therefore, a recombinant produced by a host microorganism into which an α-glucosidase gene obtained from a microorganism of the genus Aspergillus (or a gene obtained by modifying said gene) has been introduced also falls under the category of "α-glucosidase derived from a microorganism of the genus Aspergillus."

[0062] The α-glucosidase used in the present technology can be prepared from the culture medium of the microorganism from which the α-glucosidase is derived. Specific preparation methods include methods of recovering α-glucosidase from the culture medium or cells of the microorganism. For example, when an α-glucosidase-secreting microorganism is used, the cells can be recovered from the culture medium in advance by filtration, centrifugation, or the like, as necessary, and the enzyme can then be separated and / or purified. Furthermore, when an α-glucosidase-non-secreting microorganism is used, the cells can be recovered from the culture medium in advance by pressure treatment, ultrasonic treatment, or the like, and the enzyme can then be extracted and / or separated and / or purified. The enzyme separation and / or purification method can be any known protein separation and / or purification method, without any particular limitation. Examples of such methods include centrifugation, UF concentration, salting out, and various chromatography methods using ion exchange resins, etc. The isolated and / or purified enzyme can be powdered by a drying method such as freeze-drying or vacuum drying, or can be powdered using an appropriate excipient and / or drying aid in the drying method. The isolated and / or purified enzyme can also be liquefied by adding an appropriate additive and sterilizing by filtration.

[0063] In the present technology, commercially available α-glucosidase can also be used, and a preferred example of a commercially available α-glucosidase is α-glucosidase derived from Aspergillus microorganisms manufactured by Amano Enzyme Inc.

[0064] The content of α-glucosidase in the cooked rice improver according to the present technology can be freely set as long as it does not impair the effects of the present technology. The content of α-glucosidase can be set to, for example, 0.00055 U or more per gram of raw rice used to produce cooked rice. From the viewpoint of further enhancing the cooked rice improving effect, the content can be set to preferably 0.0027 U or more, more preferably 0.0055 U or more, even more preferably 0.055 U or more, and even more preferably 0.099 U or more.

[0065] The upper limit of the α-glucosidase content is not particularly limited as long as it does not impair the effects of the present technology, and can be set to, for example, 110 U or less, 100 U or less, 80 U or less, 70 U or less, 50 U or less, 30 U or less, 22 U or less, 11 U or less, 9 U or less, 5 U or less, 3 U or less, 1 U or less, 0.5 U or less, 0.3 U or less, 0.22 U or less, 0.17 U or less, or 0.13 U or less per 1 g of raw rice used to produce cooked rice.

[0066] In the present technology, the activity of α-glucosidase is a value measured by the measurement method described in the Examples below.

[0067] (7) Maltotriose-forming enzyme The maltotriose-forming enzyme that can be used in the present technology is an enzyme that acts on starch and has the activity of mainly producing maltotriose. The maltotriose-forming enzyme that can be used in the present technology may also have other functions as long as it has the activity of producing maltotriose.

[0068] In this technology, the use of maltotriose-producing enzymes in the production of cooked rice can achieve the effects of retaining the aroma of cooked rice, improving loosening properties, enhancing graininess, enhancing sweetness, improving hardness, and enhancing stickiness. In other words, the use of maltotriose-producing enzymes can produce well-balanced cooked rice.

[0069] The origin of the maltotriose-producing enzyme that can be used in the present technology is not particularly limited, and examples thereof include maltotriose-producing enzymes derived from microorganisms of the genera Streptomyces, Bacillus, Microbacterium, and Cellulosimicrobium. These maltotriose-producing enzymes may be used alone or in combination. Among these maltotriose-producing enzymes, maltotriose-producing enzymes derived from microorganisms of the genus Microbacterium are preferred, and maltotriose-producing enzymes derived from Microbacterium sp. are more preferred. Specifically, enzymes that exhibit substrate specificity acting on amylose, amylopectin, glycogen, and starch can be used.

[0070] Here, "maltotriose synthase derived from Microbacterium sp." means a maltotriose synthase produced by a microorganism classified as Microbacterium sp. (which may be a wild-type strain or a mutant strain), or a maltotriose synthase obtained by genetic engineering techniques using a maltotriose synthase gene. Therefore, a recombinant produced by a host microorganism into which a maltotriose synthase gene obtained from Microbacterium sp. (or a gene obtained by modifying said gene) has been introduced also falls under the category of "maltotriose synthase derived from Microbacterium sp."

[0071] The maltotriose-forming enzyme used in the present technology can be prepared from a culture solution of a microorganism from which the maltotriose-forming enzyme is derived. Specific preparation methods include recovering the maltotriose-forming enzyme from the culture solution or cells of the microorganism. For example, when a maltotriose-forming enzyme-secreting microorganism is used, the cells can be recovered from the culture solution in advance by filtration, centrifugation, or the like, as necessary, and the enzyme can then be separated and / or purified. Furthermore, when a maltotriose-forming enzyme-nonsecreting microorganism is used, the cells can be recovered from the culture solution in advance by pressure treatment, ultrasonic treatment, or the like, as necessary, and the enzyme can then be extracted and / or separated and / or purified. The enzyme separation and / or purification method can be any known protein separation and / or purification method, without any particular limitation, and examples thereof include centrifugation, UF concentration, salting out, and various chromatography methods using ion exchange resins, etc. The isolated and / or purified enzyme can be powdered by a drying method such as freeze-drying or vacuum drying, or can be powdered using an appropriate excipient and / or drying aid in the drying method. The isolated and / or purified enzyme can also be liquefied by adding an appropriate additive and sterilizing by filtration.

[0072] In the present technology, commercially available products can also be used as the maltotriose-producing enzyme, and a preferred example of a commercially available product is the maltotriose-producing enzyme derived from Microbacterium sp. manufactured by Amano Enzyme Inc.

[0073] The content of the maltotriose-forming enzyme in the cooked rice modifier according to the present technology can be freely set as long as it does not impair the effects of the present technology. The content of the maltotriose-forming enzyme can be set to, for example, 0.006 U or more per 1 g of raw rice used to produce cooked rice, and from the viewpoint of further enhancing the cooked rice modifying effect, it can be set to preferably 0.03 U or more, more preferably 0.06 U or more, even more preferably 0.6 U or more, and even more preferably 1.08 U or more.

[0074] The upper limit of the content of maltotriose-forming enzyme is not particularly limited as long as it does not impair the effects of the present technology, but can be set to, for example, 1200 U or less, 1000 U or less, 800 U or less, 600 U or less, 400 U or less, 300 U or less, 240 U or less, 150 U or less, 120 U or less, 100 U or less, 80 U or less, 50 U or less, 30 U or less, 10 U or less, 5 U or less, 3 U or less, 2.4 U or less, 1.8 U or less, or 1.32 U or less per 1 g of raw rice used to produce cooked rice.

[0075] In the present technology, the activity of the maltotriose synthase is a value measured by the measurement method described in the Examples below.

[0076] (8) α-Amylase The α-amylase that can be used in the present technology is an enzyme that acts on starch and mainly hydrolyzes α-1,4 glycosidic bonds. The α-amylase that can be used in the present technology may also have other functions as long as it has α-amylase activity.

[0077] This technology uses α-amylase to produce cooked rice, which can improve the loosening properties and increase stickiness of cooked rice. Generally, when the stickiness of cooked rice increases, the loosening properties decrease, but this technology has found that adding α-amylase makes it possible to obtain cooked rice that achieves both the contradictory properties of loosening and stickiness.

[0078] The origin of the α-amylase that can be used in the present technology is not particularly limited, and examples thereof include α-amylases derived from microorganisms of the genus Aspergillus (e.g., Aspergillus oryzae, Aspergillus niger, etc.) and the genus Bacillus (e.g., Bacillus amyloliquefaciens, Bacillus subtilis, Bacillus licheniformis, etc.), preferably α-amylases derived from microorganisms of the genus Bacillus, more preferably α-amylases derived from Bacillus amyloliquefaciens.

[0079] Here, "α-amylase derived from Bacillus amyloliquefaciens" means an α-amylase produced by a microorganism classified as Bacillus amyloliquefaciens (whether a wild-type strain or a mutant strain), or an α-amylase obtained by genetic engineering techniques using an α-amylase gene. Therefore, a recombinant produced by a host microorganism into which an α-amylase gene obtained from Bacillus amyloliquefaciens (or a modified version of said gene) has been introduced also falls under the category of "α-amylase derived from Bacillus amyloliquefaciens."

[0080] The α-amylase used in the present technology can be prepared from a culture medium of a microorganism from which the α-amylase is derived. Specific preparation methods include recovering the α-amylase from the culture medium or cells of the microorganism. For example, when an α-amylase-secreting microorganism is used, the cells can be recovered from the culture medium in advance by filtration, centrifugation, or the like, as necessary, and the enzyme can then be separated and / or purified. When an α-amylase-nonsecreting microorganism is used, the cells can be recovered from the culture medium in advance by pressure treatment, ultrasonic treatment, or the like, and the enzyme can then be extracted and / or separated and / or purified. The enzyme can be separated and / or purified by any known protein separation and / or purification method, without any particular limitation. Examples of the enzyme separation and / or purification method include centrifugation, UF concentration, salting out, and various chromatography methods using ion exchange resins, etc. The separated and / or purified enzyme can be powdered by drying methods such as freeze-drying and vacuum drying, or by using an appropriate excipient and / or drying aid in the drying method. The isolated and / or purified enzyme can also be liquefied by adding an appropriate additive and sterilizing by filtration.

[0081] In the present technology, commercially available α-amylase can also be used, and a preferred example of a commercially available α-amylase is α-amylase (derived from Bacillus amyloliquefaciens) manufactured by Amano Enzyme Inc.

[0082] The content of α-amylase in the cooked rice improver according to the present technology can be freely set as long as it does not impair the effects of the present technology. The content of α-amylase can be set to, for example, 0.022 U or more per gram of raw rice used to produce cooked rice, and from the viewpoint of further enhancing the cooked rice improving effect, it can be set to preferably 0.11 U or more, more preferably 0.22 U or more, even more preferably 2.25 U or more, and even more preferably 4.05 U or more.

[0083] The upper limit of the α-amylase content is not particularly limited as long as it does not impair the effects of the present technology, and can be set to, for example, 4500 U or less, 4000 U or less, 3000 U or less, 1000 U or less, 900 U or less, 700 U or less, 500 U or less, 450 U or less, 350 U or less, 200 U or less, 100 U or less, 80 U or less, 60 U or less, 40 U or less, 20 U or less, 10 U or less, 9 U or less, 7 U or less, 6.75 U or less, or 4.95 U or less per 1 g of raw rice used to produce cooked rice.

[0084] In the present technology, the α-amylase activity is a value measured by the measurement method described in the Examples below.

[0085] (9) 4-α-Glucanotransferase The 4-α-glucanotransferase (EC 2.4.1.25) used in the present technology is an enzyme that catalyzes a chemical reaction in which a portion of 1,4-α-glucan is transferred to another portion of a carbohydrate such as glucose or 1,4-α-D-glucan. The 4-α-glucanotransferase used in the present technology may also be an enzyme that has other functions as long as it acts on polysaccharides and oligosaccharides having α-1,4 glycosidic bonds and has the activity of transferring maltotriose units to saccharides.

[0086] In this technology, cooked rice is produced using the above-mentioned cyclodextrin-forming enzyme and 4-α-glucanotransferase in combination, thereby making it possible to obtain firm cooked rice with a good grainy texture.

[0087] The 4-α-glucanotransferase may be derived from either a plant or a microorganism. Examples of plant-derived 4-α-glucanotransferase include 4-α-glucanotransferase derived from potato (Solanum tuberosum L.) tubers. Examples of microorganism-derived 4-α-glucanotransferase include 4-α-glucanotransferase derived from actinomycetes (Streptomyces avermitilis, Streptomyces cinnamoneus, Streptomyces griseus, Streptomyces thermoviolaceus, and Streptomyces violaceoruber) or bacteria (Agrobacterium radiobacter). radiobacter), Arthrobacter spp., Bacillus spp., Erwinia spp., Geobacillus pallidus, Geobacillus stearothermophilus, Gluconobacter oxydans, Leuconostoc mesenteroides, Paenibacillus alginolyticus, Pimelobacter spp., Protaminobacter spp., Pseudomonas spp., Serratia spp., Sporosarcina globispora Examples of 4-α-glucanotransferases include 4-α-glucanotransferases derived from the genera Bacillus globispora and Thermus, and Aeribacillus pallidus. These 4-α-glucanotransferases may be used alone or in combination.Among these, from the viewpoint of the effect of improving the quality of cooked rice, it is preferable to use a 4-α-glucanotransferase derived from a microorganism, it is more preferable to use a 4-α-glucanotransferase derived from Aeribacillus, and it is even more preferable to use a 4-α-glucanotransferase derived from Aeribacillus pallidus (including the species formerly known as Geobacillus pallidus).

[0088] Here, "4-α-glucanotransferase derived from Aeribacillus pallidus" means a 4-α-glucanotransferase produced by a microorganism classified as Aeribacillus pallidus (whether a wild-type strain or a mutant strain), or a 4-α-glucanotransferase obtained by genetic engineering techniques using a 4-α-glucanotransferase gene. Therefore, a recombinant produced by a host microorganism into which a 4-α-glucanotransferase gene obtained from Aeribacillus pallidus (or a gene obtained by modifying said gene) has been introduced also falls under the category of "4-α-glucanotransferase derived from Aeribacillus pallidus."

[0089] The 4-α-glucanotransferase used in the present technology can be prepared from the culture medium of a microorganism from which the above-mentioned 4-α-glucanotransferase is derived. Specific preparation methods include methods in which 4-α-glucanotransferase is recovered from the culture medium or cells of the above-mentioned microorganism. For example, when a 4-α-glucanotransferase-secreting microorganism is used, the cells can be recovered from the culture medium in advance by filtration, centrifugation, or the like, as necessary, and the enzyme can then be separated and / or purified. Furthermore, when a 4-α-glucanotransferase-nonsecreting microorganism is used, the cells can be recovered from the culture medium in advance by pressure treatment, ultrasonic treatment, or the like, and the enzyme can then be extracted and / or separated and / or purified. The enzyme separation and / or purification method can be any known protein separation and / or purification method, without any particular limitation. Examples include centrifugation, UF concentration, salting out, and various chromatography methods using ion exchange resins, etc. The isolated and / or purified enzyme can be powdered by a drying method such as freeze-drying or vacuum drying, or can be powdered using an appropriate excipient and / or drying aid in the drying method. The isolated and / or purified enzyme can also be liquefied by adding an appropriate additive and sterilizing by filtration.

[0090] In the present technology, commercially available 4-α-glucanotransferases can also be used, and preferred examples of commercially available products include 4-α-glucanotransferase derived from Aeribacillus pallidus (Geobacillus pallidus) manufactured by Amano Enzyme Inc.

[0091] The content of 4-α-glucanotransferase in the cooked rice modifying agent according to the present technology can be freely set as long as it does not impair the effects of the present technology. The content of 4-α-glucanotransferase can be set to, for example, 0.015 U or more per gram of raw rice used to produce cooked rice, and from the viewpoint of further enhancing the cooked rice modifying effect, it can be set to preferably 0.05 U or more, 0.075 U or more, more preferably 0.15 U or more, even more preferably 1.5 U or more, and even more preferably 2.7 U or more.

[0092] The upper limit of the content of 4-α-glucanotransferase is not particularly limited as long as it does not impair the effects of the present technology, but can be set to, for example, 3000 U or less, 1000 U or less, 800 U or less, 600 U or less, 300 U or less, 100 U or less, 50 U or less, 10 U or less, 5 U or less, 4 U or less, or 3 U or less per 1 g of raw rice used to produce cooked rice.

[0093] In the present technology, the activity of 4-α-glucanotransferase is a value measured by the measurement method described in the Examples below.

[0094] (10) Other Components The cooked rice modifier according to the present technology can be used in combination with other components as long as the action and effect of the present technology are not impaired. Examples of other components that can be used include excipients, pH adjusters, colorants, flavoring agents, disintegrants, lubricants, stabilizers, enzymes, and other components that are commonly used in formulations. Furthermore, components with known or future functions can also be used in combination as appropriate depending on the purpose.

[0095] 2. Cooked Rice Modification Method The cooked rice modification method according to the present technology is a method including an enzyme addition step of adding one or more enzymes selected from a cyclodextrin-forming enzyme, lipase, cellulase, hemicellulase, protease, α-glucosidase, maltotriose-forming enzyme, and α-amylase, or a cyclodextrin-forming enzyme and 4-α-glucanotransferase, to rice, and / or a rice cooking step of cooking rice to which one or more enzymes selected from a cyclodextrin-forming enzyme, lipase, cellulase, hemicellulase, protease, α-glucosidase, maltotriose-forming enzyme, and α-amylase, or a cyclodextrin-forming enzyme and 4-α-glucanotransferase have been added.

[0096] The enzyme addition step and the rice cooking step may be carried out at the same facility or at different facilities. For example, one facility may carry out the enzyme addition step and cook the enzyme-added rice obtained, or one facility may carry out the enzyme addition step and distribute the enzyme-added rice obtained, and another facility may carry out the step of cooking the enzyme-added rice.

[0097] In the cooked rice modification method according to the present technology, in addition to the enzyme addition step and / or rice cooking step, it is also possible to appropriately select and perform a soaking step, a preserving step, a freezing step, a thawing step, a processing step, a recovery step, and other steps commonly used in the production of cooked rice. Below, the raw materials used in the present technology and each step will be described in detail.

[0098] (1) Raw materials In the present technology, rice is used as a raw material. The type of rice is not particularly limited, and for example, one or more types of rice such as Japonica rice, Indica rice, Javanica rice, etc. can be used. In addition, either non-glutinous rice or glutinous rice can be used, or a blend of non-glutinous rice and glutinous rice can also be used. Furthermore, the degree of rice polishing is not particularly limited, and one or more types of rice, such as brown rice, polished rice with germ, half-polished rice, seven-part polished rice, polished rice, and no-wash rice, can be used in combination. In addition, new rice, old rice, very old rice, or a blend of these may be used.

[0099] If necessary, the rice can be made into a multigrain rice blended with grains other than rice (for example, barley, germinated brown rice, adzuki beans, black beans, glutinous millet, sorghum, glutinous foxtail millet, amaranth, quinoa, pearl oats, barnyard millet, corn, black sesame, white sesame, etc.), and various ingredients and seasonings can be used depending on the purpose and use.

[0100] (2) Enzyme Addition Step The enzyme addition step is a step of adding one or more enzymes selected from cyclodextrin-forming enzymes, lipases, cellulases, hemicellulases, proteases, α-glucosidases, maltotriose-forming enzymes, α-amylases, and 4-α-glucanotransferases to rice. These enzymes may be used alone or in combination of two or more. When using a combination of two or more enzymes, the two or more enzymes may be added to the starch-containing material simultaneously or separately. When adding two or more enzymes separately, the order in which they are added is not particularly limited. Note that the details and amounts of each enzyme are the same as those of the enzymes used in the cooked rice modifier described above, and therefore will not be described here.

[0101] The specific method for adding the enzyme is not particularly limited, and as long as the enzyme can be added to rice before the rice cooking step described below, it can be added by any method and at any timing. Examples include a method of adding the enzyme to raw rice, a method of adding the enzyme to washed rice, a method of adding the enzyme when the rice is soaked in water, and a method of adding the enzyme to the rice immediately before cooking, and the enzyme can also be added in two or more separate steps.

[0102] (3) Soaking Step The soaking step is a step of soaking rice in water. The soaking step is not an essential step in the present technology, but is preferably performed from the viewpoint of smoothly proceeding with the enzyme treatment of the rice. The timing of the enzyme treatment on the rice may be during the soaking step, during the rice cooking step described below, or during both the soaking step and the rice cooking step.

[0103] The soaking step may be performed simultaneously with the enzyme addition step or in any order. That is, rice to which enzymes have been added may be soaked in water, or the enzymes may be added to rice soaked in water. Further enzymes may be added when the rice to which enzymes have been added is soaked in water. Furthermore, the same or different enzymes may be added in multiple batches to the rice soaked in water.

[0104] The various conditions in the soaking process can be freely set as long as they do not impair the effects of the present technology. For example, when an enzyme is used in the soaking process, the pH, temperature, and reaction time can be set according to the physicochemical properties of the enzyme used, such as the optimal pH, stable pH range, optimal temperature, and temperature stability. The optimal conditions can be determined through preliminary experiments. Below, examples of soaking conditions when using each enzyme are shown.

[0105] [Cyclodextrin-forming enzyme] When rice to which a cyclodextrin-forming enzyme has been added is soaked in water, the pH can be set, for example, to 3.0 to 11.0, preferably 4.0 to 9.0, and more preferably 5.0 to 7.0. The temperature can be set, for example, to 30°C to 90°C, preferably 30°C to 80°C, and more preferably 30°C to 50°C. The incubation time can be set, for example, to 10 minutes to 48 hours, preferably 15 minutes to 24 hours, and more preferably 30 minutes to 4 hours.

[0106] [Lipase] When lipase-added rice is soaked in water, the pH can be set, for example, to 3.0 to 9.0, preferably 4.0 to 8.0, and more preferably 5.0 to 7.0. The temperature can be set, for example, to 25°C to 60°C, preferably 25°C to 50°C, and more preferably 25°C to 40°C. The reaction time can be set, for example, to 10 minutes to 48 hours, preferably 30 minutes to 24 hours, and more preferably 1 hour to 4 hours.

[0107] [Cellulase] When rice to which cellulase has been added is soaked in water, the pH can be set, for example, to 2.0 to 9.0, preferably 4.0 to 8.0, and more preferably 5.0 to 7.0. The temperature can be set, for example, to 20°C to 70°C, preferably 25°C to 60°C, and more preferably 25°C to 50°C. The reaction time can be set, for example, to 10 minutes to 48 hours, preferably 30 minutes to 24 hours, and more preferably 1 hour to 4 hours.

[0108] [Hemicellulase] When rice to which hemicellulase has been added is soaked in water, the pH can be set, for example, to 2.0 to 11.0, preferably 3.0 to 10.0, 4.0 to 8.0, and more preferably 5.0 to 7.0. The temperature can be set, for example, to 20°C to 60°C, preferably 25°C to 50°C, and more preferably 25°C to 40°C. The reaction time can be set, for example, to 1 to 30 hours, preferably 30 minutes to 20 hours, and more preferably 1 to 4 hours.

[0109] [Protease] When rice to which protease has been added is soaked in water, the pH can be set, for example, to 4.0 to 11.0, preferably 4.5 to 8.0, and more preferably 5.0 to 7.0. The temperature can be set, for example, to 20°C to 70°C, preferably 25°C to 60°C, and more preferably 25°C to 50°C. The incubation time can be set, for example, to 1 to 30 hours, preferably 30 minutes to 20 hours, and more preferably 1 to 4 hours.

[0110] [α-Glucosidase] When rice to which α-glucosidase has been added is soaked in water, the pH can be set, for example, to 3.0 to 8.0, preferably 4.0 to 7.5, and more preferably 5.0 to 7.0. The temperature can be set, for example, to 20°C to 70°C, preferably 25°C to 60°C, and more preferably 25°C to 50°C. The incubation time can be set, for example, to 1 to 30 hours, preferably 30 minutes to 20 hours, and more preferably 1 to 4 hours.

[0111] [Maltotriose-forming enzyme] When rice to which a maltotriose-forming enzyme has been added is soaked in water, the pH can be set, for example, to 4.0 to 10.0, preferably 4.5 to 9.0, and more preferably 5.0 to 7.0. The temperature can be set, for example, to 20°C to 70°C, preferably 25°C to 60°C, and more preferably 25°C to 50°C. The reaction time can be set, for example, to 10 minutes to 12 hours, preferably 30 minutes to 6 hours, and more preferably 1 hour to 4 hours.

[0112] [α-Amylase] When rice to which α-amylase has been added is soaked in water, the pH can be set, for example, to 3.0 to 10.0, preferably 4.5 to 8.0, and more preferably 5.0 to 7.0. The temperature can be set, for example, to 10°C to 80°C, preferably 20°C to 70°C, and more preferably 30°C to 50°C. The incubation time can be set, for example, to 10 minutes to 12 hours, preferably 30 minutes to 6 hours, and more preferably 1 hour to 4 hours.

[0113] [4-α-Glucanotransferase] When rice to which 4-α-glucanotransferase has been added is soaked in water, the pH can be set, for example, to 3.0 to 11.0, preferably 4.0 to 9.0, and more preferably 5.0 to 7.0. The temperature can be set, for example, to 20°C to 80°C, preferably 25°C to 70°C, and more preferably 25°C to 60°C. The incubation time can be set, for example, to 10 minutes to 48 hours, preferably 15 minutes to 24 hours, and more preferably 30 minutes to 4 hours.

[0114] Other ingredients can be added to the water used in the soaking process as long as they do not impair the function and effect of the present technology. Examples of other ingredients that can be used include various seasonings, various ingredients, pH adjusters, colorants, flavoring agents, stabilizers, enzymes, etc. Furthermore, ingredients with known or future functions can also be added as appropriate depending on the purpose.

[0115] (4) Rice Cooking Step The rice cooking step is a step of cooking rice to which one or more enzymes selected from a cyclodextrin-forming enzyme, lipase, cellulase, hemicellulase, protease, α-glucosidase, maltotriose-forming enzyme, and α-amylase, or a cyclodextrin-forming enzyme and 4-α-glucanotransferase have been added.

[0116] In the present technology, rice cooking refers to heating rice while adding water. The heating method is not particularly limited, and examples include boiling, steaming, baking, microwave heating, etc., and a combination of these methods can also be used. Rice can also be cooked using a rice cooker or rice cooker pot.

[0117] The rice cooking conditions can be freely set as long as they do not impair the effects of the present technology, for example, depending on the type and amount of rice used, the type and amount of ingredients used together, the purpose of the cooked rice, etc.

[0118] (5) Storage Step The storage step is a step of storing cooked rice after cooking. The storage step is not an essential step in the present technology, but as described above, for example, cooked rice produced using a cyclodextrin-forming enzyme or cellulase can exhibit the effect of enhancing the sweetness of the cooked rice by storing it for a predetermined period of time, and cooked rice produced using α-glucosidase can exhibit the effect of improving the graininess by storing it for a predetermined period of time. Therefore, by performing the storage step, further improvement of the cooked rice can be achieved.

[0119] Various conditions in the storage step can be freely set as long as they do not impair the effects of the present technology. The storage temperature can be set, for example, to -40°C to 40°C, preferably -30°C to 30°C, and more preferably -25°C to 25°C. The storage time can be set, for example, to 1 hour or more, preferably 6 hours or more, more preferably 12 hours or more, and even more preferably 20 hours or more. The upper limit of the storage time can be set appropriately depending on the storage temperature and storage method. For example, the upper limit can be set freely to 1 year or less, 6 months or less, or 3 months or less when stored in a freezing temperature range; to 7 days or less, 5 days or less, or 3 days or less when stored in a chilled temperature range; and to 3 days or less, 2 days or less when stored in a refrigerated temperature range.

[0120] Furthermore, in the processing step described below, when processing the cooked rice into vacuum-packed cooked rice, retort-packed cooked rice, or the like, the storage time can be freely set depending on the processing method.

[0121] The preservation step may be performed by the same institution as the institution that performs the enzyme addition step and the rice cooking step, or may be performed by a different institution. For example, one institution may cook and preserve cooked rice, or one institution may distribute cooked rice and another institution may preserve the cooked rice.

[0122] (6) Freezing step The freezing step is a step of freezing cooked rice after cooking. The freezing step is not an essential step in the present technology, but can be carried out, for example, when storing cooked rice in a freezing temperature range in the storage step.

[0123] The timing of the freezing step is not particularly limited as long as it is performed after the rice cooking step, as long as it does not impair the functions and effects of the present technology. The freezing step can be performed after the storage step, or the freezing step can be performed after the storage step in a freezing temperature range. Furthermore, the freezing step can be performed after the storage step in a chilled temperature range or refrigerated temperature range, and then the freezing step can be performed again in a freezing temperature range.

[0124] The conditions for the freezing step are not particularly limited as long as they do not impair the functions and effects of the present technology, and any general freezing method can be freely adopted, for example, a method of freezing at around −20° C.

[0125] The freezing step may be performed by the same institution as the institution that performs the enzyme addition step, the rice cooking step, and the preservation step, or may be performed by a different institution. For example, one institution may freeze cooked rice and then preserve it, or one institution may freeze cooked rice and distribute it as frozen rice, and another institution may preserve the frozen rice.

[0126] (7) Thawing Step The thawing step is a step of thawing frozen cooked rice. The thawing step is not an essential step in the present technology, but for example, when a freezing step is performed, thawing can be performed before eating.

[0127] The specific method for the thawing step is not particularly limited as long as it does not impair the action and effect of the present technology, and any common thawing method can be freely adopted, such as thawing at room temperature, thawing at refrigeration temperature, thawing in running water, microwave heating, thawing in a hot water bath, steaming, boiling, baking, or other heating methods.

[0128] The thawing step may be performed by the same institution as the enzyme addition step, the rice cooking step, the storage step, and the freezing step, or may be performed by a different institution. For example, one institution may freeze and store cooked cooked rice and then thaw it, or one institution may distribute the cooked rice, another institution may perform a step of freezing the cooked rice and distribute the frozen cooked rice, and yet another institution may thaw the frozen cooked rice. It is also possible for a consumer who purchases distributed frozen cooked rice to thaw it.

[0129] (8) Processing step The processing step is a step in which cooked rice obtained through the rice cooking step is processed according to the purpose or use. The processing step is not an essential step in the present technology, but can be performed as needed.

[0130] As a specific method for the processing step, one or more common cooked rice processing methods can be selected and used as long as the action and effect of the present technology are not impaired. Examples include methods for processing cooked rice into vacuum-packed cooked rice, retort-packed cooked rice, dried cooked rice, etc., and methods for cooking and processing cooked rice into seasoned rice, fried rice, pilaf, doria, paella, porridge, rice balls, sushi, etc.

[0131] The timing of the processing step is not particularly limited as long as it is performed after the enzyme addition step, as long as it does not impair the action and effect of the present technology. For example, cooked rice obtained by performing the rice cooking step can be processed, or, for example, when using the rice in seasoned rice, pilaf, paella, etc., the rice cooking step and the processing step can be performed simultaneously. Furthermore, the processing step can be performed after thawing cooked rice that has been frozen and stored, or the cooked rice that has been processed by performing the processing step can be frozen and stored.

[0132] The processing steps, including the enzyme addition step, rice cooking step, storage step, freezing step, and thawing step, may be performed at the same facility or at different facilities. For example, one facility may process cooked rice obtained by cooking, or one facility may distribute cooked rice obtained by cooking, and another facility may process the cooked rice. It is also possible for consumers who purchase distributed cooked rice to process it.

[0133] (9) Recovery Step The recovery step is a step of recovering cooked rice or processed cooked rice obtained through an enzyme addition step and / or a rice cooking step, and, as necessary, a soaking step, a preserving step, a freezing step, a thawing step, a processing step, etc. As for the specific recovery method, one or a combination of two or more recovery methods generally used in the production of cooked rice can be used depending on the state and type of the obtained cooked rice.

[0134] The method according to the present technology described above can be embodied as including the following steps A to K. A: A step of preparing rice and, if necessary, other raw materials; B: A step of adding one or more enzymes selected from cyclodextrin-forming enzyme, lipase, cellulase, hemicellulase, protease, α-glucosidase, maltotriose-forming enzyme, and α-amylase, or a cyclodextrin-forming enzyme and 4-α-glucanotransferase, to the prepared rice, etc.; C: A step of adding water; D: A step of soaking rice in water; E: A step of cooking rice to which one or more enzymes selected from cyclodextrin-forming enzyme, lipase, cellulase, hemicellulase, protease, α-glucosidase, maltotriose-forming enzyme, and α-amylase, or a cyclodextrin-forming enzyme and 4-α-glucanotransferase have been added; F: A step of storing the cooked rice obtained; G: A step of inactivating the enzymes; H: A step of freezing the cooked rice obtained. I: A process for thawing frozen cooked rice J: A process for processing cooked rice K: A process for recovering cooked rice

[0135] Step C may be performed before, after, or simultaneously with one or more steps selected from step A, step B, and step D, and step C can be performed multiple times. Either one of steps B and E or both may be performed. Steps D, F, G, H, I, J, and K are not essential and can be performed as needed. Furthermore, step G can be performed multiple times as needed after step D, during step D, before or after step E, simultaneously with step E, or before or after step F. Furthermore, when steps E and G are performed simultaneously, the enzyme can also be inactivated by heating in the rice cooking process. That is, step E can be performed instead of step G. In addition, when multiple enzymes are used, enzyme inactivation can also be performed between the actions of the enzymes. For example, when multiple enzymes are acted on in the soaking step D, the enzyme inactivation step G can be appropriately performed during the soaking step D.

[0136] 3. Cooked Rice Production Method The cooked rice production method according to the present technology includes a rice cooking step in which rice to which a cyclodextrin-forming enzyme has been added is cooked. In the rice cooking step, rice to which 4-α-glucanotransferase has been added in addition to the cyclodextrin-forming enzyme can also be cooked. Furthermore, in addition to the rice cooking step, the cooked rice production method according to the present technology can also include an appropriate selection of steps commonly used in the production of cooked rice, such as a cyclodextrin-forming enzyme addition step, a soaking step, a storage step, a freezing step, a thawing step, a processing step, a recovery step, and other steps. The details and amounts of the cyclodextrin-forming enzyme and 4-α-glucanotransferase to be added are the same as those used in the cooked rice modifier described above, and therefore will not be described here. The details of each step are also the same as those in the cooked rice modification method described above, and therefore will not be described here.

[0137] The form of distribution of cooked rice modified by the cooked rice modification method according to the present technology or cooked rice obtained by the cooked rice manufacturing method according to the present technology is not particularly limited. For example, it can be distributed in a frozen state, a refrigerated state, a chilled state, or at room temperature. Furthermore, cooked rice that has been stored frozen, refrigerated, chilled, or at room temperature may be cooked in a store or the like and distributed as cooked processed cooked rice.

[0138] The present invention will be described in more detail below with reference to examples. Note that the examples described below are representative examples of the present invention and should not be construed as narrowing the scope of the present invention.

[0139] 1. Raw Materials The raw materials and enzymes used in the examples are shown in Table 1 below.

[0140]

[0141] 2. Enzyme Activity Measurement Method [Cyclodextrin-forming Enzyme] Cyclodextrin-forming enzyme activity can be measured using a method based on the cyclodextrin-forming enzyme activity test method in the 9th edition of the Japanese Standards for Food Additives. 20 mL of water was added to 1.0 g of potato starch, and 5 mL of sodium hydroxide TS (1 mol / L) was gradually added with stirring to form a paste. After heating in a boiling water bath for 3 minutes with stirring, 25 mL of water was added, cooled under running water, and the pH was adjusted to 5.5 with acetic acid TS (1 mol / L). Further water was added to make a 100 mL solution, which was used as the substrate solution. 10 mL of the substrate solution was measured and heated at 40°C for 10 minutes, followed by the addition and mixing of 1 mL of enzyme solution. After incubation at 40°C for 10 minutes, the reaction was stopped by adding 10 mL of hydrochloric acid TS (0.1 mol / L). To 1 mL of this reaction solution, 10 mL of iodine-potassium iodide test solution (0.4 mmol / L) was added and mixed to prepare a test solution. The iodine-potassium iodide test solution was prepared by dissolving 10.0 g of potassium iodide and 1.0 g of iodine in water to make 100 mL, and then diluting 200 times with water. A control solution was prepared using water instead of the reaction solution, and the absorbance at 660 nm of the test solution and the control solution was measured. The amount of enzyme that reduces the blue iodine coloration of starch by 1% in 1 minute was defined as 1 unit (U).

[0142] Lipase activity can be measured using a method based on the lipase activity test method in the 9th edition of the Japanese Standards for Food Additives. First, 45 g of olive oil was mixed with 150 mL of emulsion (18.5 g / L polyvinyl alcohol (fully saponified, saponification degree 98.8 ± 0.2), 1.5 g / L polyvinyl alcohol (partially saponified, saponification degree 88.8 ± 1.0)) and emulsified using a homogenizer to prepare a substrate solution. 1 mL of lipase enzyme solution was added to 5 mL of the prepared substrate solution and 4 mL of 0.1 mol / L phosphate buffer (pH 7.0), and the reaction was carried out at 37°C. After 30 minutes, 10 mL of an ethanol-acetone mixture was added to terminate the enzyme reaction. Next, 10 mL of 0.05 mol / L sodium hydroxide solution and 10 mL of an ethanol-acetone mixture were added, and the mixture was titrated to pH 10 with 0.05 mol / L hydrochloric acid. The amount of enzyme that increases 1 μmol of fatty acid per minute is defined as 1 unit (1 U).

[0143] [Cellulase] Cellulase activity can be measured using a method based on the cellulase activity test method in the 9th edition of the Japanese Standards for Food Additives. Approximately 1 g of carmellose sodium (also known as carboxymethylcellulose sodium) (degree of etherification: 0.62-0.68) was accurately weighed and dried at 105°C for 4 hours, and the weight loss was measured. Carmellose sodium equivalent to 0.625 g of the dried product was accurately weighed and placed in a 100 mL Erlenmeyer flask. 50 mL of water was added and heated to dissolve. After cooling, 10 mL of 1 mol / L acetic acid / sodium acetate buffer (pH 4.5) and water were added to make a total volume of exactly 100 mL, which served as the substrate solution. 4 mL of the substrate solution was accurately weighed and placed in a 50 mL Nessler tube. After allowing to stand at 37±0.5°C for at least 10 minutes, 1 mL of the sample solution was accurately measured and added, and the mixture was immediately shaken. This solution was left at 37±0.5°C for exactly 30 minutes, then 2 mL of alkaline copper test solution was added and shaken. The Nessler tube was then stoppered and heated in a water bath for exactly 30 minutes. After cooling with water, 2 mL of Nelson's solution was added and shaken thoroughly. 3 mL of 0.5 mol / L sodium hydroxide test solution was added and shaken to dissolve the precipitate. After leaving the solution for 20 minutes, 13 mL of 1 mol / L acetic acid / sodium acetate buffer (pH 4.5) was added. 1 mL of this solution was accurately measured, and 9 mL of 1 mol / L acetic acid / sodium acetate buffer (pH 4.5) was added and shaken thoroughly. The absorbance (A1) of this solution at a wavelength of 750 nm was measured using water as a control. Separately, 1 mL of sample solution was accurately measured and placed in a 50 mL Nessler tube. 2 mL of alkaline copper test solution was added and shaken. 4 mL of substrate solution was then accurately measured and shaken. The absorbance (A2) was measured in the same manner. Under these conditions, the amount of enzyme that increases the reducing power equivalent to 1 μmole of glucose per minute was defined as one unit of cellulase activity, and the cellulase activity (U / g, U / mL) per 1 g or 1 mL of sample was calculated using the following formula: Cellulase activity (U / g, U / mL) = G × (1 / 30) × (1 / 0.180) × n G: Amount of glucose produced (mg) calculated from the glucose calibration curve using the (A1-A2 / a) value 1 / 30: Conversion coefficient per minute 1 / 0.180: 1 μmole of glucose = 0.180 mg a: Slope of the glucose calibration curve n: Dilution factor per 1 g or 1 mL of sample

[0144] [Hemicellulase] Hemicellulase activity can be measured using a method based on the hemicellulase activity test method in the 9th edition of the Japanese Standards for Food Additives. An appropriate amount of enzyme was weighed, dissolved or uniformly dispersed in water, and appropriately diluted to prepare a sample solution. 0.50 g of xylan was weighed, approximately 30 mL of water was added, and the mixture was heated while stirring. After boiling, the mixture was boiled for 3 minutes. After cooling, water was added to this solution to make a 50 mL solution, which served as a substrate solution. 1 mL of the substrate solution was weighed into a test tube, 3 mL of 0.1 mol / L acetate buffer (pH 4.5) was added, and the mixture was heated at 40°C for 10 minutes. Then, 1 mL of the sample solution was added, shaken, and heated at 40°C for 30 minutes. 2 mL of Somogyi test solution (III) was added to this solution, mixed, and the test tube was stoppered and heated in a boiling water bath for 20 minutes, followed by immediate cooling. After cooling, 1 mL of Nelson's test solution was added to this solution, and the mixture was shaken thoroughly until the red precipitate was completely dissolved. The mixture was then left at room temperature for approximately 20 minutes, after which water was added to make a 25 mL solution. This solution was centrifuged at 3,000 rpm for 10 minutes at 25°C, and the supernatant was used as the test solution. Separately, 1 mL of the substrate solution was measured in a test tube, and 3 mL of 0.1 mol / L acetate buffer (pH 4.5) and 2 mL of Somogyi test solution (III) were added and shaken. Then, 1 mL of the sample solution was added, the test tube was stoppered, heated in a boiling water bath for 20 minutes, and immediately cooled. The following procedure was repeated to prepare the control solution. The absorbance of the test solution and the control solution was measured at a wavelength of 500 nm using water as a control. Enzyme activity was calculated by defining the amount of enzyme required to produce reducing sugar equivalent to 1 mg of xylose per minute under these conditions as 100 units.

[0145] [Protease] Protease activity can be measured using a method based on the protease activity test method in the 9th edition of the Japanese Standards for Food Additives. 5 mL of 0.6% (w / v) casein solution (0.05 mol / L sodium hydrogen phosphate, pH 8.0) was heated at 37°C for 10 minutes, after which 1 mL of a sample solution containing protease was added and immediately shaken. This solution was then allowed to stand at 37°C for 10 minutes, followed by the addition of 5 mL of trichloroacetic acid test solution (1.8% (w / v) trichloroacetic acid, 1.8% (w / v) sodium acetate, and 0.33 mol / L acetic acid), shaking, and again at 37°C for 30 minutes, followed by filtration. The first 3 mL of filtrate was discarded, and 2 mL of the next filtrate was measured, to which 5 mL of 0.55 mol / L sodium carbonate test solution and 1 mL of Folin's test solution (1→3) were added, shaken well, and allowed to stand at 37°C for 30 minutes. The absorbance AT of this solution (enzyme reaction solution) at a wavelength of 660 nm was measured, using water as a control. Separately, 1 mL of sample solution containing protease was measured, and 5 mL of trichloroacetic acid test solution (1.8% (w / v) trichloroacetic acid, 1.8% (w / v) sodium acetate, and 0.33 mol / L acetic acid) was added and shaken. 5 mL of 0.6% (w / v) casein solution (0.05 mol / L sodium hydrogen phosphate, pH 8.0) was added, immediately shaken, and left at 37°C for 30 minutes. The absorbance AB of a blank solution was measured in the same manner as the enzyme reaction solution described above, except that the blank was left at 37°C for 30 minutes. The amount of enzyme that increases the Folin test solution color product equivalent to 1 μg of tyrosine per minute was defined as 1 unit (1 U). 1 mL, 2 mL, 3 mL, and 4 mL of a 1 mg / mL tyrosine standard stock solution (0.2 mol / L hydrochloric acid) were measured, and 0.2 mol / L hydrochloric acid test solution was added to each to make a 100 mL solution. 2 mL of each solution was measured, and 5 mL of 0.55 mol / L sodium carbonate test solution and 1 mL of Folin test solution (1 → 3) were added. The mixture was immediately shaken and left at 37°C for 30 minutes. For each of these solutions, 2 mL of 0.2 mol / L hydrochloric acid test solution was measured and the resulting solution was used as a control. Absorbances A1, A2, A3, and A4 at a wavelength of 660 nm were measured. A calibration curve was created, plotting absorbances A1, A2, A3, and A4 on the vertical axis and the amount of tyrosine (μg) in 2 mL of each solution on the horizontal axis, and the amount of tyrosine (μg) per 2 mL of each solution was calculated.Protease activity (U / g, U / mL) = (AT - AB) x F x 11 / 2 x 1 / 10 x 1 / M AT: absorbance of enzyme reaction solution AB: absorbance of blank F: amount of tyrosine (µg) when the difference in absorbance obtained from the tyrosine calibration curve is 1 1 / 2: conversion coefficient to total liquid volume after reaction has stopped 1 / 10: conversion coefficient per minute of reaction time M: amount of sample (g or mL) in 1 mL of sample solution.

[0146] [α-Glucosidase] α-Glucosidase activity can be measured using a method based on Method 2 of the α-Glucosidase Activity Test in the 9th Edition of the Japanese Standards for Food Additives. (1) 2.0 g of α-methyl-D-glucoside was weighed out and dissolved in water to make 100 mL, to prepare an α-methyl-D-glucoside solution. 1 mL of the α-methyl-D-glucoside solution and 1 mL of 0.02 mol / L acetic acid / sodium acetate buffer (pH 5.0) were weighed into a test tube and left at 40°C for 10-15 minutes. Then, 0.5 mL of an aqueous solution containing transglucosidase (enzyme solution) was added and shook well. This was left at 40°C for exactly 60 minutes. After exactly 60 minutes, the tube was placed in a boiling water bath, heated for exactly 5 minutes, and cooled under running water. (2) 3 mL of the color-developing solution from Glucose CII-Test Wako (Fujifilm Wako Pure Chemical Industries, Ltd.) was weighed into a test tube, and 0.2 mL of the reaction solution obtained in (1) was added. The mixture was shaken well and then allowed to stand at 40°C for exactly 5 minutes. The absorbance (E60) of this solution at 505 nm was measured using water as a control. Separately, as a blank, 1 mL of 0.02 mol / L acetic acid / sodium acetate buffer (pH 5.0) and 0.5 mL of an aqueous solution containing transglucosidase (enzyme solution) were weighed into a test tube, heated in a boiling water bath for exactly 5 minutes, and then cooled under running water. After cooling, 1 mL of α-methyl-D-glucoside solution was added, and the absorbance (E0) was measured in the same manner as above. (3) Glucose standard solution I or II from Glucose CII-Test Wako was diluted with water to the specified concentration (20 mg / dL or 40 mg / dL). Three mL of Glucose CII Test Wako coloring solution was weighed into a test tube, and 0.2 mL of the above glucose solution was added. The mixture was shaken well and then allowed to stand at 40°C for exactly 5 minutes. The absorbance (ES) of this solution was measured at a wavelength of 505 nm using water as a control. Separately, the absorbance (EB) was measured in the same manner as above using 0.2 mL of water instead of the glucose solution as a blank. A glucose calibration curve was created from the obtained absorbances, and the amount of glucose (μg) (G) at an absorbance difference of 1.000 was calculated. Under these conditions, the amount of enzyme required to produce 1 μg of glucose in 2.5 mL of reaction solution in 60 minutes was defined as one unit (1 U), and calculated using the following formula:α-Glucosidase activity (U / g, U / mL) = (E60 - E0) x G x 2.5 / 0.1 x n / 0.5 E60: absorbance of reaction solution E0: absorbance of blank solution G: amount of glucose (μg) when the absorbance difference is 1.000 2.5: volume of reaction system solution (mL) 0.1: volume of reaction solution collected (mL) 0.5: volume of enzyme solution collected (mL) n: dilution factor per 1 g or 1 mL of sample.

[0147] [Maltotriose-forming enzyme] The activity of maltotriose-forming enzyme can be measured by a method based on the maltotriohydrolase activity test method in the 9th edition of the Japanese Standards for Food Additives. The enzyme was allowed to act on soluble starch as a substrate, and the resulting reducing sugars were colorimetrically quantified by the Somogyi-Nelson method. 0.5 mL of soluble starch solution and 0.1 mol / L acetic acid / sodium acetate buffer (pH 6.0) (0.05 mol / L CaCl) were added to a 50 mL Nessler tube. ２ 0.4 mL of the solution (containing 100% ethanol) was weighed, shaken well, and left at 40±0.5°C for 10-15 minutes, after which 0.1 mL of the sample solution was added and immediately shaken. This solution was left at 40±0.5°C for exactly 15 minutes, after which 1 mL of alkaline copper test solution was added, shaken, the container was capped, and the solution was heated in a boiling water bath for exactly 20 minutes and immediately cooled. After cooling, 1 mL of Nelson's solution was added, and the solution was shaken well until the red precipitate of cuprous oxide was completely dissolved. After leaving the solution at room temperature for 20 minutes, 22 mL of water was added and shaken well. The absorbance of this solution was measured at a wavelength of 520 nm using water as a control. One unit was defined as the production of reducing sugar equivalent to 1 μmol of glucose per minute.

[0148] [Method for measuring α-amylase activity] 10 mL of a 1% potato starch substrate solution (0.1 mol / L acetic acid (pH 5.0)) was heated at 37°C for 10 minutes, after which 1 mL of a sample solution containing α-amylase was added and immediately shaken. This solution was left to stand at 37°C for 10 minutes, after which 1 mL of this solution was added to 10 mL of 0.1 mol / L hydrochloric acid test solution and immediately shaken. Next, 0.5 mL of this solution was measured, and 10 mL of 0.0002 mol / L iodine test solution (Japanese Pharmacopoeia) was added. After shaking, the absorbance (AT) at a wavelength of 660 nm was measured using water as a control. Separately, 1 mL of water was added instead of the sample solution, and the procedure was repeated to measure the absorbance (AB). The 0.0002 mol / L iodine test solution (Japanese Pharmacopoeia) was prepared by adding 10 mL of water to 12.7 g of iodine and 25 g of potassium iodide, mixing well, adding water to make 100 mL, and then diluting 2500 times with water. α-Amylase activity was calculated using the following formula. The amount of enzyme that reduces the color of potato starch caused by iodine by 10% in 1 minute is defined as 1 unit (1 U). α-Amylase activity (U / g, U / mL) = {(AB - AT) / AB} x 1 / W AT: absorbance of reaction solution AB: absorbance of blank solution W: amount of sample (g or mL) in 1 mL of sample solution

[0149] [Method for Measuring 4-α-Glucanotransferase Activity] 180 mg of maltotetraose (Nagasevita Co., Ltd.) was weighed and placed in a 20 mL volumetric flask. Approximately 15 mL of 10 mmol / L MES buffer (pH 6.5) was added to dissolve the maltotetraose. Once dissolved, 10 mmol / L MES buffer (pH 6.5) was added to the solution, and the resulting volume was adjusted to 20 mL. This was used as the substrate solution. 2 mL of the substrate solution was weighed into a test tube and allowed to stand at 40 ± 0.5 °C for 10-15 minutes. 0.5 mL of the sample solution was then added, shaken well, and allowed to stand at 40 ± 0.5 °C for exactly 60 minutes. After standing, the tube was placed in a boiling water bath, heated for exactly 5 minutes, and then cooled under running water. The glucose produced was quantified using a Labo Assay Glucose (Fujifilm Wako Pure Chemical Corporation). The Lab Assay Glucose kit consists of a coloring agent containing mutarotase, glucose oxidase, peroxidase, 4-aminoantipyrine, and ascorbic acid oxidase, and a buffer containing phosphate buffer (pH 7.1) and phenol. It can determine glucose concentration by measuring the red pigment produced by the oxidative condensation of phenol and 4-aminoantipyrine. Under these conditions, one unit of enzyme is defined as the amount of enzyme that produces 1 μmol of glucose per minute.

[0150] 3. Experimental Example [Experimental Example 1] (1) Method 375 g of pre-washed Koshihikari rice produced in Niigata Prefecture in 2022 was weighed and placed in a rice cooker. The enzymes shown in Table 1 were dissolved in 525 g of water and added to the rice cooker. The rice cooker was then set in the rice cooker and soaked for 2 hours. The temperature of the water used during soaking was set to 30°C. After soaking, the rice was cooked in the usual manner using a rice cooker ("HOMESWAN SRC-35" manufactured by Niitsu Koki Co., Ltd.). After steaming for 10 minutes, the cooked rice was loosened with a rice paddle, wrapped in double-layered paper towels, and allowed to cool to room temperature for 1 hour.

[0151] (2) Sensory Evaluation 20 g of the untreated (control) and cooled cooked rice from Examples 1 to 8 was weighed out and made into onigiri using a commercially available mini-sized rice ball mold. Sensory evaluation was performed. The rice balls produced as described above were evaluated for aroma, whiteness, loosening, graininess, sweetness, hardness / softness, and stickiness immediately after completion and after storage at 10°C for one day according to the evaluation criteria shown in Table 2 below. Five panelists evaluated the rice using a scoring system ranging from -3 to 3 points, with the control example being given a score of 0.

[0152]

[0153] (3) The results after cooling and before storage are shown in Table 3 below.

[0154]

[0155] (4) Discussion As shown in Table 3, the following points were confirmed for each enzyme.

[0156] [Cyclodextrin-forming enzyme] (Example 1) The addition of cyclodextrin-forming enzyme improved the aroma, loosening, and stickiness of cooked rice after cooling and before storage. In other words, the addition of cyclodextrin-forming enzyme was effective in maintaining the aroma of cooked rice, improving loosening, and increasing stickiness. Furthermore, after storage at 10°C for 1 day, Example 1 was able to maintain the aroma, loosening, graininess, hardness, and stickiness compared to the untreated rice (control example) by adding cyclodextrin-forming enzyme. In other words, it was effective in inhibiting aging of cooked rice when stored at 10°C. Furthermore, the cooked rice to which cyclodextrin-forming enzyme was added was confirmed to have the effect of enhancing the sweetness of cooked rice after storage at 10°C for 1 day. Furthermore, the action of cyclodextrin-forming enzyme can also be expected to have a high dietary fiber effect.

[0157] [Lipase] (Example 2) The addition of lipase improved the sweetness, softness, graininess, and stickiness of cooked rice after cooling and before storage. Generally, improving stickiness leads to a decrease in graininess, but with this technology, it was confirmed that adding lipase can produce cooked rice that combines the contradictory properties of graininess and stickiness. Furthermore, after storage at 10°C for 1 day, compared to the untreated (control) example, the addition of lipase in Example 2 was able to maintain and enhance the sweetness, aroma, softness, loosening, graininess, and stickiness, thereby demonstrating a staling inhibitory effect.

[0158] [Cellulase] (Example 3) By adding cellulase, the hardness of cooked rice after cooling and before storage increased, improving the graininess. It was found that adding cellulase resulted in harder cooked rice with a good graininess. Furthermore, the cooked rice to which cellulase was added was confirmed to have the effect of enhancing the sweetness of cooked rice by storing it at 10 ° C for 1 day.

[0159] [Hemicellulase] (Example 4) The addition of hemicellulase improved the graininess, softness, and stickiness of cooked rice after cooling and before storage. Generally, improving stickiness and softness reduces graininess, but with this technology, it was confirmed that adding hemicellulase can produce cooked rice that combines the contradictory properties of graininess with stickiness and softness. It was also confirmed that adding hemicellulase enhanced the sweetness of cooked rice. Furthermore, after storage at 10°C for 1 day, it was confirmed that adding hemicellulase in Example 4 maintained stickiness and softness compared to the untreated control. In other words, the addition of hemicellulase also confirmed an anti-aging effect.

[0160] [Protease] (Example 5) The addition of protease improved the softness and stickiness of cooked rice after cooling and before storage. It was shown that adding protease resulted in softer cooked rice. Furthermore, after storage at 10°C for 1 day, Example 5 was able to maintain softness and stickiness by adding protease compared to the untreated (control) rice, demonstrating anti-aging effects. Furthermore, it was found that this technology reduces the aroma and sweetness unique to cooked rice by adding protease. In other words, it was confirmed that the flavor of cooked rice can be modified by adding protease. This flavor modification effect persisted even after storage at 10°C for 1 day. Reducing the aroma and sweetness unique to cooked rice can reduce the impact on other seasonings and aromas, making it promising for a variety of applications.

[0161] [α-Glucosidase] (Example 6) The addition of α-glucosidase improved the aroma, sweetness, softness, and stickiness of cooked rice after cooling and before storage. This indicates that the addition of α-glucosidase enhances the aroma and sweetness, and softens cooked rice. This technology, in particular, confirmed the effect of enhancing the sweetness of cooked rice by adding α-glucosidase. Furthermore, after storage at 10°C for 1 day, Example 6 was able to maintain the aroma, graininess, sweetness, softness, and stickiness compared to the untreated rice (control), demonstrating an anti-aging effect. In particular, the sweetness-enhancing effect was maintained even after storage at 10°C for 1 day.

[0162] [Maltotriose-forming enzyme] (Example 7) The addition of maltotriose-forming enzyme improved the aroma, loosening properties, graininess, sweetness, hardness, and stickiness of cooked rice after cooling and before storage. It was shown that the addition of maltotriose-forming enzyme can produce better-balanced cooked rice.

[0163] [α-Amylase] (Example 8) The addition of α-amylase improved the loosening and stickiness of cooked rice after cooling and before storage. Generally, improving stickiness leads to poor loosening, but with this technology, it was confirmed that adding α-amylase could produce cooked rice that achieved both the contradictory properties of loosening and stickiness.

[0164] [Experimental Example 2] (1) Method: 100 g of 2023 Niigata Prefecture-grown Koshihikari polished rice (raw rice) was weighed and placed in a colander. The polished rice was gently stirred clockwise by hand 10 times in a bowl containing purified water that had been brought to room temperature. The purified water was replaced and the same process was repeated four times. After washing, the rice was drained and transferred to a rice cooker. The enzymes shown in Table 4 were dissolved in 160 g of water and added to the rice cooker. The rice cooker was then set in the rice cooker and soaked at room temperature for 1 hour. After soaking, the rice was cooked in the usual manner using a rice cooker (Panasonic: SR-03GP). After steaming for 10 minutes, the cooked rice was placed in a Tupperware container, spread out, and allowed to cool to room temperature.

[0165] (2) Sensory Evaluation Using the same methods as in Experimental Example 1, the loosening properties, graininess, and hardness / softness of the dough after cooling and before storage were evaluated.

[0166] (3) The results are shown in Table 4 below.

[0167]

[0168] (4) Discussion The addition of cyclodextrin-forming enzyme and 4-α-glucanotransferase increased the hardness of cooked rice after cooling and before storage, improving the graininess. It was found that the combined use of cyclodextrin-forming enzyme and 4-α-glucanotransferase produced hard cooked rice with a good graininess.

Claims

1. A cooked rice improver comprising one or more enzymes selected from a cyclodextrin-forming enzyme, a lipase, a cellulase, a hemicellulase, a protease, an α-glucosidase, a maltotriose-forming enzyme, and an α-amylase, or a cyclodextrin-forming enzyme and a 4-α-glucanotransferase.

2. The cooked rice improver according to claim 1, which improves one or more qualities of cooked rice selected from aroma, loosening properties, graininess, sweetness, hardness, softness, and stickiness.

3. A method for improving cooked rice, comprising an enzyme addition step of adding to rice one or more enzymes selected from cyclodextrin-forming enzyme, lipase, cellulase, hemicellulase, protease, α-glucosidase, maltotriose-forming enzyme, and α-amylase, or a cyclodextrin-forming enzyme and 4-α-glucanotransferase.

4. A method for improving cooked rice, comprising a rice cooking step of cooking rice to which one or more enzymes selected from a cyclodextrin-forming enzyme, lipase, cellulase, hemicellulase, protease, α-glucosidase, maltotriose-forming enzyme, and α-amylase, or a cyclodextrin-forming enzyme and 4-α-glucanotransferase have been added.

5. A method for improving cooked rice according to claim 3 or 4, which improves one or more qualities of cooked rice selected from aroma, loosening properties, graininess, sweetness, hardness, softness, and stickiness.

6. A method for producing cooked rice, comprising a rice cooking step of cooking rice to which a cyclodextrin-forming enzyme has been added.

7. The method for producing cooked rice according to claim 6, wherein the rice is rice to which 4-α-glucanotransferase has been added.

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