Composition and method for improving the texture of cooked rice, composition for improving the stickiness of cooked rice, composition for improving the graininess and graininess of cooked rice, composition for improving the plumpness of cooked rice, and method for producing cooked rice

Abstract

To provide an effective composition for improving the texture of cooked rice, composition for improving the stickiness of cooked rice, composition for improving the particulate appearance of cooked rice, and composition for improving the soft feeling of cooked rice, and a method for producing cooked rice by using the composition for improving the texture.SOLUTION: A composition for improving the texture of cooked rice contains reduced starch syrup and branching enzyme as an active ingredient.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a composition for improving the texture of cooked rice, a composition for improving the stickiness of cooked rice, a composition for improving the graininess and granularity of cooked rice, a composition for improving the plumpness of cooked rice, and a method for producing cooked rice. [Background technology]

[0002] Processed rice products come in a variety of forms, including packaged rice, retort rice, chilled and room temperature lunch boxes, rice balls, frozen fried rice, etc. In recent years, the ready-meal market at convenience stores and mass retailers has expanded, and within that, demand for processed rice products such as rice balls and lunch boxes has increased.

[0003] In processed cooked rice products for ready-to-eat meals, deterioration of texture due to starch aging during the manufacturing to sales process has been an issue. In particular, in chilled products, texture deterioration tends to be more pronounced, so maintaining a texture close to that of cooked rice has been an important point.

[0004] Several technologies have been proposed to prevent deterioration in the texture of cooked rice. Patent Document 1 discloses a method for increasing the stickiness, flavor, and umami of cooked rice by using a reduced starch hydrolysate. Patent Document 2 discloses a method for imparting hardness and elasticity to starch-containing foods by using a branching enzyme and α-glucosidase in combination. Patent Document 3 discloses a method for producing a cooked rice product that deteriorates slowly, which includes a step of contacting rice with an aqueous enzyme solution containing amylase and a branching enzyme. Patent Document 4 discloses a method for producing cooked rice, which is characterized by adding a sugar alcohol to cooked rice. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 7-236435 [Patent Document 2] Re-tabled publication No. 2014-115894 [Patent Document 3] Special Publication No. 2015-525564 [Patent Document 4] Japanese Patent Application Publication No. 1-60341 Summary of the Invention [Problem to be solved by the invention]

[0006] Processed cooked rice products for ready-to-eat meals have been well-received in the market, and by effectively preventing deterioration in the texture of cooked rice, it will be possible to provide the ready-to-eat market with processed cooked rice products that better meet consumer needs. For this reason, the development of a new method for improving the texture of cooked rice has been eagerly awaited.

[0007] Under these circumstances, the present inventors conducted extensive research and discovered a method for improving the texture of cooked rice by using reduced starch syrup in combination with a branching enzyme, and completed the present invention. The present invention aims to provide effective compositions for improving the texture of cooked rice, compositions for improving stickiness, compositions for improving graininess and granularity, and compositions for improving plumpness, as well as a method for producing cooked rice using the texture-improving compositions. [Means for solving the problem]

[0008] In order to achieve the above object, the composition for improving texture according to the first aspect of the present invention comprises: It contains reduced starch syrup and branching enzymes as active ingredients.

[0009] For example, the reduced starch syrup is the following (a) or (b): The composition according to claim 1 ; (a) reduced starch syrup having a sugar composition containing 1 to 50% by mass of monosaccharides, 6 to 55% by mass of disaccharides, 1 to 35% by mass of trisaccharides, 0 to 13% by mass of tetrasaccharides, and 0 to 82% by mass of pentasaccharides or more; (b) Reduced starch syrup obtained by reducing starch syrup having a dextrose equivalent of 26 or more and 70 or less.

[0010] The composition for improving the stickiness of cooked rice according to the second aspect of the present invention comprises: It contains reduced starch syrup and branching enzymes as active ingredients.

[0011] For example, the reduced starch syrup is the following (a) or (b): The composition according to claim 1 ; (a) reduced starch syrup having a sugar composition containing 1 to 50% by mass of monosaccharides, 6 to 55% by mass of disaccharides, 1 to 35% by mass of trisaccharides, 0 to 13% by mass of tetrasaccharides, and 0 to 82% by mass of pentasaccharides or more; (b) Reduced starch syrup obtained by reducing starch syrup having a dextrose equivalent of 26 or more and 70 or less.

[0012] A composition for improving the graininess and granularity of cooked rice according to a third aspect of the present invention comprises: It contains reduced starch syrup and branching enzymes as active ingredients.

[0013] For example, the reduced starch syrup is the following (a) or (b): The composition according to claim 1 ; (a) reduced starch syrup having a sugar composition containing 1 to 50% by mass of monosaccharides, 6 to 55% by mass of disaccharides, 1 to 35% by mass of trisaccharides, 0 to 13% by mass of tetrasaccharides, and 0 to 82% by mass of pentasaccharides or more; (b) Reduced starch syrup obtained by reducing starch syrup having a dextrose equivalent of 26 or more and 70 or less.

[0014] A composition for improving the fluffyness of cooked rice according to a fourth aspect of the present invention comprises: It contains reduced starch syrup and branching enzymes as active ingredients.

[0015] For example, the reduced starch syrup is the following (a) or (b): The composition according to claim 1 ; (a) reduced starch syrup having a sugar composition containing 1 to 50% by mass of monosaccharides, 6 to 55% by mass of disaccharides, 1 to 35% by mass of trisaccharides, 0 to 13% by mass of tetrasaccharides, and 0 to 82% by mass of pentasaccharides or more; (b) Reduced starch syrup obtained by reducing starch syrup having a dextrose equivalent of 26 or more and 70 or less.

[0016] A method for producing cooked rice according to a fifth aspect of the present invention is as follows: The method includes a step of adding the texture improving composition according to the first aspect of the present invention and cooking the rice. [Effects of the Invention]

[0017] According to the present invention, it is possible to provide an effective composition for improving the texture of cooked rice, a composition for improving stickiness, a composition for improving graininess and granularity, and a composition for improving plumpness, as well as a method for producing cooked rice using the texture-improving composition. [Brief explanation of the drawings]

[0018] [Figure 1] FIG. 1 shows the results of measuring the texture of cooked rice. DETAILED DESCRIPTION OF THE INVENTION

[0019] First, the composition for improving the texture of cooked rice according to the present invention will be described in detail.

[0020] The composition for improving the texture of cooked rice of the present invention contains reduced starch syrup and a branching enzyme as active ingredients. Cooked rice cooked with the addition of this composition has a plump and soft texture, excellent graininess and distinct grains, is made sticky and less dry, and changes over time after cooking (increased hardness, reduced stickiness, and reduced plumpness) are also reduced.

[0021] Reduced starch syrup is a type of sugar alcohol obtained by reducing starch syrup. Sugar alcohols are compounds obtained by reducing sugars with an aldehyde group (-CHO) and converting the terminal to an alcohol (-CH2OH). Sugar alcohols are generally obtained by reducing (hydrogenating) sugars using a catalyst under high pressure. Starch syrup is obtained by saccharifying starch with acids or enzymes, and is a mixture of monosaccharides (glucose) and polysaccharides (oligosaccharides, dextrins, etc.). Therefore, reduced starch syrup is also a mixture containing two or more sugar alcohols, including monosaccharide sugar alcohols and polysaccharide sugar alcohols (disaccharides, trisaccharides, tetrasaccharides, or more).

[0022] Depending on the degree of saccharification, reduced starch syrup may be divided into highly saccharified reduced starch syrup (30 to 50% by mass of monosaccharide alcohols, 20 to 50% by mass of disaccharide alcohols, and 25% by mass or less of sugar alcohols of three or more sugars when the total weight of sugars is 100%), medium saccharified reduced starch syrup (less than 30% by mass of monosaccharide alcohols and less than 50% by mass of sugar alcohols of five or more sugars when the total weight of sugars is 100%), and low saccharified reduced starch syrup (50% by mass or more of sugar alcohols of five or more sugars when the total weight of sugars is 100%), but any of these can be used in the present invention.

[0023] As the reduced starch syrup, for example, (i) reduced starch syrup having a sugar composition of 1 to 50 mass% monosaccharides, 6 to 55 mass% disaccharides, 1 to 35 mass% trisaccharides, 0 to 13 mass% tetrasaccharides, and 0 to 82 mass% pentasaccharides or more sugars is used, and preferably, (i) highly saccharified reduced starch syrup having a sugar composition of 37 to 50 mass% monosaccharides, 26 to 55 mass% disaccharides, 1 to 21 mass% trisaccharides, 0 to 10 mass% tetrasaccharides, and 0 to 8 mass% pentasaccharides or more sugars is used. The following can be used: (i) original starch syrup; (ii) medium-sugar reduced starch syrup with a sugar composition of 2 to 10% by mass of monosaccharides, 43 to 55% by mass of disaccharides, 15 to 35% by mass of trisaccharides, 1 to 5% by mass of tetrasaccharides, and 1 to 38% by mass of pentasaccharides or more; or (iii) low-sugar reduced starch syrup with a sugar composition of 1 to 10% by mass of monosaccharides, 6 to 21% by mass of disaccharides, 7 to 23% by mass of trisaccharides, 5 to 13% by mass of tetrasaccharides, and 50 to 82% by mass of pentasaccharides or more.

[0024] In the present invention, the sugar composition refers to the mass percentage of each sugar relative to the total mass of sugars, i.e., the mass percentage of each sugar when the total mass of sugars is taken as 100.

[0025] The sugar composition can be confirmed using high-performance liquid chromatography (HPLC). That is, reduced starch syrup or water is subjected to HPLC as a sample to obtain a chromatogram. In the chromatogram, the sum of the areas of all peaks corresponds to the "total mass of sugars," and the area of ​​each peak corresponds to the "mass of each sugar." Therefore, the mass percentage of each sugar in the sample can be calculated as the ratio of the area of ​​each peak to the sum of the areas of all detected peaks. HPLC conditions can be set appropriately according to standard methods, but the following conditions can be exemplified. (HPLC conditions) Column: Shodex SUGAR KS-802 HQ (8.0 mm ID x 300 mm) x 2 Eluent: High purity water Flow rate: 1.0mL / min Injection volume: 200μL Column temperature: 50℃ Detection: Differential refractive index detector Shodex RI

[0026] In the present invention, commercially available reduced starch syrup may be used as is, or may be produced according to a method known to those skilled in the art. Known methods for producing reduced starch syrup include a reduction reaction in which hydrogen is added to starch syrup (raw material sugar) as a raw material.

[0027] The reduction reaction by hydrogenation can be carried out, for example, by charging a 40 to 75% by mass aqueous solution of raw sugar together with a reduction catalyst into a high-pressure reactor, adjusting the hydrogen pressure in the reactor to 4.9 to 19.6 MPa, the reaction solution temperature to 70 to 180°C, and mixing and stirring until no more hydrogen is absorbed. The reduction catalyst is then separated, and the mixture is decolorized and desalted by ion exchange resin treatment, and if necessary, activated carbon treatment, etc., and then concentrated to a predetermined concentration to produce a highly concentrated reduced starch syrup.

[0028] In another aspect, the reduced starch syrup used in the present invention may be reduced starch syrup obtained by reducing starch syrup having a dextrose equivalent of 26 or more and 70 or less.

[0029] Now, let's explain about dextrose equivalent. Because reduced starch syrup is produced by reducing starch syrup, the degree of saccharification of reduced starch syrup corresponds to the degree of saccharification of the starch syrup. In other words, the higher the degree of saccharification of the raw starch syrup, the higher the degree of saccharification of the reduced starch syrup, and the lower the degree of saccharification of the raw starch syrup, the lower the degree of saccharification of the reduced starch syrup. Dextrose equivalent (DE) is generally used as an indicator of the degree of saccharification of starch syrup. DE is the ratio (percentage) of reducing sugars in a sample to the total solid content when the reducing sugars are measured as glucose. The maximum DE value is 100, which means that all of the solid content is glucose, and the lower the DE, the more oligosaccharides and polysaccharides there are.

[0030] The DE of starch syrup can be measured by the following method. <<DE measurement method>> Accurately weigh 2.5 g of sample and dissolve in water to make 200 mL. Measure 10 mL of this solution, add 10 mL of 1 / 25 mol / L iodine solution (Note 1) and 15 mL of 1 / 25 mol / L sodium hydroxide solution (Note 2), and leave in the dark for 20 minutes. Next, add 5 mL of 2 mol / L hydrochloric acid (Note 3), mix, and then titrate with 1 / 25 mol / L sodium thiosulfate solution (Note 4). When the solution turns slightly yellow near the end of the titration, add 2 drops of starch indicator (Note 5) and continue titrating. The end point is when the solution's color disappears. Determine the blank value using water, and calculate DE using the following equation 1. (Note 1) 1 / 25 mol / L iodine solution: Place 20.4 g of potassium iodide and 10.2 g of iodine in a 2 L measuring flask, dissolve in a small amount of water, and then add water up to the marked line. (Note 2) 1 / 25 mol / L sodium hydroxide solution: Place 3.2 g of sodium hydroxide in a 2 L measuring flask, dissolve it in a small amount of water, and then add water up to the marked line. (Note 3) 2 mol / L hydrochloric acid: Gradually add 150 mL of hydrochloric acid to 750 mL of water while stirring. (Note 4) 1 / 25 mol / L sodium thiosulfate solution: Place 20 g of sodium thiosulfate in a 2 L measuring flask, dissolve it in a small amount of water, and then add water up to the marked line. (Note 5) Starch indicator: Dissolve 5 g of soluble starch in 500 mL of water, and dissolve 100 g of sodium chloride in this.

[0031]

number

[0032] Branching enzymes (EC 2.4.1.18) are transferases (6-α-glucanotransferases) that act on glucose-based polysaccharides such as starch and glycogen. These enzymes catalyze the cleavage of α-1,4 bonds and the transfer of α-1,6 bonds to another site. In this specification, branching enzymes may also be referred to simply as "enzymes."

[0033] In the present invention, branching enzyme activity can be confirmed according to a modified version of the method described in Takata et al., Applied and Environmental Microbiology (1994), p. 3097 (assay A). Specifically, 50 μL of enzyme solution and 50 μL of substrate solution (type III amylose dissolved in 0.1 M Tris buffer to a concentration of 0.1%) are mixed and incubated at 60°C for 30 minutes. 2 mL of iodine reagent is then added and incubated at room temperature for 15 minutes to form an amylose-iodine complex. The iodine reagent is prepared by mixing 0.5 mL of 1N HCl with 0.5 mL of a stock solution (0.26 g of I2 and 2.6 g of KI dissolved in 10 mL of water), followed by dilution with water to a total volume of 130 mL. The absorbance at 660 nm (A 660 The control sample is prepared by replacing the enzyme solution with water. The branching enzyme activity is measured by the difference in A between the test sample and the control sample. 660 One unit (U) of branching enzyme activity is measured as the difference in A at 60°C and pH 7.0 by 1% per minute. 660 is defined as the amount of enzyme that can reduce

[0034] The branching enzyme has an optimum temperature in the range of 60° C. to 120° C., preferably 60° C. to 100° C., more preferably 60° C. to 80° C., and even more preferably 60° C. to 70° C. In addition, it preferably has an optimum pH in the range of 6 to 8 (relative activity of 70% or more).

[0035] The branching enzyme can be a commercially available food-grade branching enzyme preparation, such as "Denazyme BBR LIGHT" (Nagase ChemteX) or glycotransferase "Amano" L (Amano Enzyme).

[0036] Alternatively, the branching enzyme may be extracted and purified from naturally occurring organisms such as plants and microorganisms according to standard methods. Examples of organisms that possess branching enzymes include Rhodothermus obamensis, Rhodothermus marinus, Arthrobacter globiformis, Bacillus megaterium, Streptococcus mitis, Salmonella typhimurium, the alga Cyanidium caldarium, Escherichia coli, Bacillus caldolyticus, Geobacillus stearothermophilus, and Synechococcus.

[0037] Methods for preparing branching enzymes from naturally occurring organisms include, for example, culturing a microorganism that produces the branching enzyme (culturing step), isolating microbial cells from the culture medium (microbial cell isolation step), and extracting and purifying the branching enzyme from the microbial cells (extraction and purification step). In the culturing step, the microorganism is cultured in a medium containing nutrient sources that can be utilized by the microorganism. The medium may be in either liquid or solid form as long as it promotes the production of the branching enzyme. However, a liquid medium is preferred because it is easy to prepare and allows for culturing to a high bacterial concentration. Examples of nutrient sources include carbon sources, nitrogen sources, and inorganic salts. Examples of carbon sources include glucose, glycerin, dextrin, starch, molasses, and animal and vegetable oils. Examples of nitrogen sources include soybean flour, corn steep liquor, cottonseed meal, meat extract, peptone, yeast extract, ammonium sulfate, sodium nitrate, and urea. Examples of inorganic salts include sodium, potassium, calcium, magnesium, manganese, iron, cobalt, zinc, and phosphate. The culture method may be static culture, shaking culture, or aerated culture. However, aerated culture is preferred because it allows efficient supply of air and nutrients to the fungal cells. The culture temperature may be, for example, 25°C to 70°C, preferably 30°C to 60°C. The pH of the medium may be, for example, pH 5 to pH 8. The culture time may be, for example, 1 to 7 days, and the culture is stopped when the amount of branching enzyme accumulated within the fungal cells reaches a maximum. The fungal cell isolation step may be carried out by, for example, centrifugation, filtration, or vacuum distillation. Examples of extraction methods used in the extraction and purification step include physical methods such as freeze-thawing, high-pressure homogenization, and bead treatment; and chemical methods such as treatment with agents that damage cell membranes, methods that involve a sudden change in osmotic pressure, and alkali and enzyme treatment. The purification method in the extraction and purification step can be an appropriate combination of known methods depending on the degree of purification of the target branching enzyme, such as ultrafiltration using a filter membrane with a molecular weight exclusion of 5,000 or 10,000, fractionation using ammonium sulfate or ethanol, and purification by chromatography. The branching enzyme may be used as a liquid solution containing the branching enzyme, or may be used as a powdered enzyme obtained by vacuum drying or freeze-drying.

[0038] An example of a branching enzyme that can be suitably used in the present invention is a polypeptide having the amino acid sequence (a) or (b) below (hereinafter, sometimes referred to as "the polypeptide"): (a) an amino acid sequence having 90% or more sequence identity with SEQ ID NO: 2; (b) an amino acid sequence encoded by any one of the following nucleic acid sequences (a) to (c): (A) the nucleic acid sequence of SEQ ID NO: 1; (a) a nucleic acid sequence complementary to SEQ ID NO: 1 (SEQ ID NO: 3); (c) A nucleic acid sequence that hybridizes with (a) or (b) under stringent conditions.

[0039] Here, SEQ ID NO: 2 is equal to the amino acid sequence of SEQ ID NO: 2 described in Japanese Patent No. 4732591, and SEQ ID NO: 1 is equal to the nucleic acid sequence of SEQ ID NO: 1 described in the same publication. SEQ ID NO: 2 is the amino acid sequence of the branching enzyme of Rhodothermus ovamensis strain JCM 9785 (hereinafter sometimes referred to as the "JCM9785 branching enzyme"). SEQ ID NO: 1 is the nucleic acid sequence encoding the amino acid sequence of SEQ ID NO: 2. SEQ ID NO: 3 is a nucleic acid sequence complementary to SEQ ID NO: 1. In other words, the present polypeptide refers to a branching enzyme that is identical to or highly similar to the JCM9785 branching enzyme in terms of amino acid sequence and enzymatic activity.

[0040] The polypeptide can be extracted and purified from Rhodothermus ovamensis strain JCM 9785 (RIKEN Microbial Culture Collection) by the above-mentioned method. Alternatively, it can be chemically synthesized based on the amino acid sequence information (a) or (b) above, using chemical synthesis methods such as the Fmoc method (fluorenylmethyloxycarbonyl method) or the tBoc method (t-butyloxycarbonyl method), or using various commercially available peptide synthesizers.

[0041] The present polypeptide can also be obtained by genetic recombination techniques. In this method, the present polypeptide is expressed in a suitable expression system. Specifically, the nucleic acid sequences (A) to (C) are inserted into an appropriate vector to obtain a recombinant vector, and the recombinant vector is then introduced into an appropriate host to obtain a transformant. The obtained transformant is then cultured to express the present polypeptide. Here, the nucleic acid sequences (A) to (C) can be synthesized based on the sequence information using various commercially available DNA synthesizers, or can be obtained by polymerase chain reaction (PCR) using DNA encoding the JCM9785 branching enzyme as a template. Furthermore, the Escherichia coli clone described in Japanese Patent Publication No. 4732591 (NMO049443, Accession No. DSM12607) can also be used as such a transformant.

[0042] The identity of amino acid sequences can be confirmed by standard methods, for example, using programs such as FASTA (http: / / www.genome.JP / tools / fasta / ), Basic local alignment search tool (BLAST; http: / / www.ncbi.nlm.nih.gov), and Position-Specific Iterated BLAST (PSI-BLAST; http: / / www.ncbi.nlm.nih.gov). The term "identity" refers to consistency and is used interchangeably with "identity."

[0043] Stringent hybridization conditions include prehybridization and hybridization in 5x SSPE, 0.3% SDS, 200 μg / mL sheared and denatured salmon sperm DNA, 50% formamide at 42°C according to standard Southern blotting procedures, followed by three washes in 2x SSC, 0.2% SDS at 65°C or 70°C for 15 minutes each.

[0044] The type of rice to which the texture-improving composition of the present invention is applied is not particularly limited, and for example, both non-glutinous rice and glutinous rice can be used.Furthermore, the type of cooked rice in the present invention is not particularly limited, and in addition to plain rice, seasoned cooked rice or cooked rice with ingredients such as red rice, steamed sticky rice, seasoned rice, and mixed rice can be included.

[0045] In the present invention, cooked rice can be obtained, for example, by washing rice, draining the water, adding a predetermined amount of water and a predetermined amount of reduced starch syrup and branching enzyme to the rice, soaking the rice for a predetermined time, and then cooking the rice in a known rice cooker.

[0046] In the texture-improving composition of the present invention, the content of reduced starch syrup is, for example, 0.2 to 10% (solids weight) of raw rice. The content of branching enzyme is, for example, 0.001 to 1.0% of the amount of raw rice, or 25 to 25,000 U per 100 g of raw rice. The contents of reduced starch syrup and branching enzyme can be increased or decreased as appropriate, as long as the effects of the present invention are achieved.

[0047] The form of the texture-improving composition of the present invention is not particularly limited and may be a solid, semi-solid, slurry, liquid, gel, etc. Furthermore, the texture-improving composition of the present invention may contain other ingredients suitable for rice cooking in addition to the reduced starch syrup and branching enzyme.

[0048] In the present invention, the texture-improving effect of cooked rice can be evaluated, for example, by items such as (i) hardness, (ii) stickiness, (iii) graininess / grain structure, and (iv) plumpness. For example, the texture of cooked rice obtained by applying the texture-improving composition of the present invention can be determined to be improved if it is (i) less hard (softer), (ii) more sticky (sticky), (iii) more graininess / grain structure (a grainy texture is perceived), or (iv) more plump (plump) than cooked rice obtained without the texture-improving composition of the present invention. Examples of methods for evaluating these items include sensory evaluation of cooked rice by eating or visually observing it, and methods using known rheometers, hardness / viscosity meters, texture analyzers, etc. The texture-improving effect of cooked rice can be obtained by cooking rice using the texture-improving composition of the present invention immediately after cooking, several hours after cooking, or several days after cooking. For example, cooked rice that has been stored in a refrigerator for several days after cooking generally becomes hard and loses stickiness, but by cooking rice using the texture-improving composition of the present invention, the rice can maintain its texture, such as softness and stickiness, even when stored in a refrigerator for several days after cooking.

[0049] In other aspects of the present invention, there are provided a composition for improving the hardness of cooked rice, which contains reduced starch syrup and a branching enzyme as active ingredients; a composition for improving the stickiness of cooked rice, which contains reduced starch syrup and a branching enzyme as active ingredients; a composition for improving the graininess and granularity of cooked rice, which contains reduced starch syrup and a branching enzyme as active ingredients; or a composition for improving the plumpness of cooked rice, which contains reduced starch syrup and a branching enzyme as active ingredients.

[0050] In the composition for improving the hardness of cooked rice described above, for example, (i) reduced starch syrup having a sugar composition of 1 to 50 mass% monosaccharides, 6 to 55 mass% disaccharides, 1 to 35 mass% trisaccharides, 0 to 13 mass% tetrasaccharides, and 0 to 82 mass% pentasaccharides or more sugars is used.

[0051] In the above-mentioned composition for improving the stickiness of cooked rice, for example, (i) reduced starch syrup having a sugar composition of 1 to 50% by mass of monosaccharides, 6 to 55% by mass of disaccharides, 1 to 35% by mass of trisaccharides, 0 to 13% by mass of tetrasaccharides, and 0 to 82% by mass of pentasaccharides or more is used, and from the viewpoint of the stickiness improving effect, preferably, a medium-sugar reduced starch syrup having a sugar composition of 2 to 10% by mass of monosaccharides, 43 to 55% by mass of disaccharides, 15 to 35% by mass of trisaccharides, 1 to 5% by mass of tetrasaccharides, and 1 to 38% by mass of pentasaccharides or more; or a low-sugar reduced starch syrup having a sugar composition of 1 to 10% by mass of monosaccharides, 6 to 21% by mass of disaccharides, 7 to 23% by mass of trisaccharides, 5 to 13% by mass of tetrasaccharides, and 50 to 82% by mass of pentasaccharides or more can be used. Regarding the stickiness-improving effect of cooked rice, for example, if cooked rice obtained by applying the stickiness-improving composition of the present invention has enhanced stickiness (stickiness) as determined by sensory evaluation after eating compared to cooked rice obtained without the addition of the stickiness-improving composition of the present invention, it can be determined that the stickiness-improving effect is present. The stickiness-improving effect can also be evaluated by measuring the "adhesiveness" of cooked rice using a rheometer (a viscoelasticity measuring device).

[0052] In the composition for improving the granular texture and graininess of cooked rice described above, for example, (i) reduced starch syrup having a sugar composition of 1 to 50% by mass of monosaccharides, 6 to 55% by mass of disaccharides, 1 to 35% by mass of trisaccharides, 0 to 13% by mass of tetrasaccharides, and 0 to 82% by mass of pentasaccharides or more sugars may be used. From the viewpoint of the effect of improving the granular texture and graininess, preferably, (i) highly saccharified reduced starch syrup having a sugar composition of 37 to 50% by mass of monosaccharides, 26 to 55% by mass of disaccharides, 1 to 21% by mass of trisaccharides, 0 to 10% by mass of tetrasaccharides, and 0 to 8% by mass of pentasaccharides or more sugars may be used; or (ii) medium-saccharified reduced starch syrup having a sugar composition of 2 to 10% by mass of monosaccharides, 43 to 55% by mass of disaccharides, 15 to 35% by mass of trisaccharides, 1 to 5% by mass of tetrasaccharides, and 1 to 38% by mass of pentasaccharides or more sugars may be used. Regarding the effect of improving the graininess and granularity of cooked rice, for example, if cooked rice obtained by applying the composition for improving graininess and granularity of the present invention has an enhanced graininess and granularity (a more perceptible graininess) as determined by sensory evaluation through visual observation, compared to cooked rice obtained without adding the composition for improving graininess and granularity of the present invention, it can be determined that the effect of improving graininess and granularity is achieved.

[0053] In the above-mentioned composition for improving the plumpness of cooked rice, for example, (i) reduced starch syrup having a sugar composition of 1 to 50% by mass of monosaccharides, 6 to 55% by mass of disaccharides, 1 to 35% by mass of trisaccharides, 0 to 13% by mass of tetrasaccharides, and 0 to 82% by mass of pentasaccharides or more is used, and from the viewpoint of the plumpness improving effect, preferably, reduced starch syrup having a sugar composition of 2 to 10% by mass of monosaccharides, 43 to 55% by mass of disaccharides, 15 to 35% by mass of trisaccharides, 1 to 5% by mass of tetrasaccharides, and 1 to 38% by mass of pentasaccharides or more can be used. Regarding the plumpness improving effect of cooked rice, for example, if cooked rice obtained by applying the plumpness improving composition of the present invention has an enhanced plumpness (plumper) in a sensory evaluation by eating compared to cooked rice obtained without the addition of the plumpness improving composition of the present invention, it can be determined that the plumpness improving effect is exhibited. The plumpness improving effect can also be evaluated by sensory evaluation through visual observation or by a texture analyzer or the like.

[0054] Next, a method for producing cooked rice according to the present invention will be described.

[0055] The method for producing cooked rice according to the present invention comprises the step of adding the texture-improving composition of the present invention and cooking the rice.

[0056] An example of a method for producing cooked rice according to the present invention is shown below. For example, rice is washed and drained, and a predetermined amount of water and a predetermined amount of reduced starch syrup and branching enzyme are added to the rice, and the rice is soaked for a predetermined time, and then cooked in a known rice cooker. The reduced starch syrup, branching enzyme, rice, cooked rice, etc. are the same as those described above.

[0057] The cooked rice obtained by the production method of the present invention has an improved texture, for example, improved (i) hardness, (ii) stickiness, (iii) graininess and granularity, and (iv) plumpness. Details of the texture improvement effects including (i) to (iv) and the method for evaluating them are the same as those described above.

[0058] As described above, the cooked rice texture-improving composition and production method according to the present invention can provide cooked rice that has a plump and soft texture, excellent graininess and distinct grains, is imparted with stickiness to reduce dryness, and undergoes reduced changes over time after cooking (increased hardness, reduced stickiness, and reduced plumpness). While texture deterioration due to starch aging during the manufacturing and sales process has been an issue for processed cooked rice products for home-cooked meals, the texture-improving composition and production method according to the present invention can provide cooked rice with improved texture. Furthermore, texture deterioration over time has been a particular problem for chilled products in the home-cooked meal market. However, the texture-improving composition and production method according to the present invention can maintain texture, such as softness and stickiness, even when stored in a refrigerator for several days after cooking, thereby providing cooked rice that meets market needs. [Example]

[0059] The present invention will be specifically described below with reference to examples, although the present invention is not limited to these examples.

[0060] In the following examples, percentages (%) refer to mass % unless otherwise specified. In addition, in the examples, the high saccharification reduced starch syrup, medium saccharification reduced starch syrup, and low saccharification reduced starch syrup were commercially available products (manufactured by Bussan Food Science Co., Ltd.) listed in Table 1.

[0061] [Table 1]

[0062] In the following examples, a polypeptide consisting of an amino acid sequence having 90% or more sequence identity with SEQ ID NO: 2 was used as the branching enzyme (hereinafter referred to as "enzyme").

[0063] Example 1 The texture of rice cooked with reduced starch syrup and enzymes was examined.

[0064] Reduced starch syrup and enzymes were added to raw rice, which was then cooked, and a sensory evaluation was conducted on the texture of the cooked rice. As comparative examples, the same experiment was conducted with raw rice only (control), reduced starch syrup alone, and enzyme alone. The composition of each sample is shown in Table 2.

[0065] [Table 2]

[0066] (Cooking method) (1) Each reduced starch syrup, enzyme, and water were added to washed raw rice and soaked for 1 hour. (2) Rice was cooked normally in a rice cooker. (3) After loosening the cooked rice, it was wrapped in Rice Guard and left to cool at room temperature for 15 minutes. (4) The mixture was divided into approximately 150g portions in lidded containers and stored in the refrigerator for 3 days. (5) The range was increased to prepare each sample.

[0067] (Evaluation method) A sensory evaluation was conducted by six panelists (A-F) on four items: hardness, stickiness, graininess / particle size, and plumpness. The evaluation method involved scoring using the following indicators, and the average of the responses was calculated. For the "overall evaluation," each panelist scored the product on a scale from "favorable (5 points)" to "unfavorable (1 point)." "5 points" = obviously strong / hard "4 points" = slightly strong / hard "3 points" = control equivalent "2 points" = slightly weak / soft "1 point" = obviously weak / soft

[0068] (result) The results of the sensory evaluation are shown in Table 3. The individual scores of six panelists (A-F) are shown in Table 4. Compared to enzyme alone, the combined use of reduced starch syrup and enzyme resulted in a higher overall score for all reduced starch syrup test groups, with particularly significant improvements observed in the categories of stickiness, granular texture, and plumpness. Furthermore, when looking at the reduced starch syrup by type, SE600 demonstrated a significant improvement in the category of "granular texture" compared to the control, SE600 alone, and enzyme alone. Furthermore, Sweet OL demonstrated a higher "overall score" compared to the control, sweet OL alone, and enzyme alone, as well as significant improvements in the categories of "stickiness," "granular texture," and "plumpness" compared to the control, sweet OL alone, and enzyme alone. Furthermore, SE30 demonstrated a higher "overall score" compared to the control, SE30 alone, and enzyme alone, as well as significant improvements in the category of "stickiness" compared to the control, SE30 alone, and enzyme alone.

[0069] [Table 3]

[0070] [Table 4]

[0071] Example 2 The stickiness of cooked rice was investigated by measuring the texture of rice cooked with the addition of reduced starch syrup (sweet OL) and enzymes.

[0072] The stickiness of cooked rice was examined by measuring the "adhesion" of samples of cooked rice prepared using a combination of sweet OL and enzymes on the day of cooking and after 3 days of refrigerated storage. The cooking method was the same as in Example 1, including the amount of enzyme added, except that sweet OL was used in an amount of 3% (solids weight) of raw rice. As a comparative example, a similar experiment was also conducted using raw rice alone (control).

[0073] The measurement method was to weigh approximately 15 g of cooked rice into a cup and measure its compression with a circular plunger using a Yamaden rheometer. More specifically, the rice was compressed to a strain rate of 50%, and the "adhesion" (J / m 3 ) was measured. The samples stored in the refrigerator for 3 days were removed from the microwave and allowed to cool for 10 minutes before measurement.

[0074] The measurement results of "adhesion" are shown in Figure 1. In Figure 1, the vertical axis represents adhesion (J / m 3 ) on the horizontal axis, "Day 0" represents the day of cooking, and "Day 3" represents the results after three days of refrigerated storage. On Day 0, it was shown that the combination of enzymes and sweet OL increased adhesiveness compared to the control. Furthermore, with the control, adhesiveness decreased over time from Day 0 to Day 3, whereas with the combination of enzymes and sweet OL, no decrease in adhesiveness was observed, demonstrating that quality (stickiness) was maintained even three days after refrigerated storage after cooking.

[0075] From the above, it was shown that adding reduced starch syrup and enzymes together during cooking improves the texture of cooked rice, such as stickiness, graininess, and plumpness, and that these textures are maintained even after cooking, preventing deterioration of texture over time.

Claims

1. The present invention contains the following reduced starch syrup and branching enzyme (C) or (D) as active ingredients: a composition for improving the texture of cooked rice, (C) reduced starch syrup having a sugar composition in which monosaccharide alcohols account for less than 30% by mass and sugar alcohols of five or more sugars account for less than 50% by mass, when the total weight of sugars is taken as 100%; (D) Reduced starch syrup obtained by reducing starch syrup having a dextrose equivalent of 45 or more but less than 70.

2. The reduced starch syrup and branching enzyme of (E) or (F) below are comprised: a composition for improving the texture of cooked rice, (E) reduced starch syrup having a sugar composition in which sugar alcohols of five or more sugars account for 50% by mass or more when the total weight of sugars is 100%; (F) Reduced starch syrup obtained by reducing starch syrup having a dextrose equivalent of 26 to 30.

3. A method of treating a skin condition comprising the following reduced starch syrup and branching enzyme (C), (D), (E), or (F) as active ingredients: A composition for improving the stickiness of cooked rice, (C) reduced starch syrup having a sugar composition in which monosaccharide alcohols account for less than 30% by mass and sugar alcohols of five or more sugars account for less than 50% by mass, when the total weight of sugars is taken as 100%; (D) reduced starch syrup obtained by reducing starch syrup having a dextrose equivalent of 45 or more but less than 70; (E) reduced starch syrup having a sugar composition in which sugar alcohols of five or more sugars account for 50% by mass or more when the total weight of sugars is 100%; (F) Reduced starch syrup obtained by reducing starch syrup having a dextrose equivalent of 26 to 30.

4. Contains reduced starch syrup and branching enzymes as active ingredients. A composition for improving the graininess and granularity of cooked rice.

5. The reduced starch syrup is the following (a) or (b):

7. The composition according to claim 6 ; (a) reduced starch syrup having a sugar composition containing 1 to 50% by mass of monosaccharides, 6 to 55% by mass of disaccharides, 1 to 35% by mass of trisaccharides, 0 to 13% by mass of tetrasaccharides, and 0 to 82% by mass of pentasaccharides or more; (b) Reduced starch syrup obtained by reducing starch syrup having a dextrose equivalent of 26 or more and 70 or less.

6. A method of treating a skin condition comprising the following reduced starch syrup and branching enzyme (A), (B), (C), or (D) as active ingredients: A composition for improving the fluffy feeling of cooked rice, characterized by: (A) reduced starch syrup having a sugar composition of 30 to 50% by mass of monosaccharide alcohols, 20 to 50% by mass of disaccharide alcohols, and 25% by mass or less of trisaccharide or higher sugar alcohols, when the total weight of sugars is 100%; (B) reduced starch syrup obtained by reducing starch syrup having a dextrose equivalent of 70 or more; (C) reduced starch syrup having a sugar composition in which monosaccharide alcohols account for less than 30% by mass and sugar alcohols of five or more sugars account for less than 50% by mass, when the total weight of sugars is taken as 100%; (D) Reduced starch syrup obtained by reducing starch syrup having a dextrose equivalent of 45 or more but less than 70.

7. A method for producing cooked rice, comprising the step of adding the composition according to any one of claims 1 to 6 and cooking the rice.

8. A method for improving the texture of cooked rice, comprising the step of adding the texture-improving composition according to claim 1 or 2 and cooking the rice.

9. A method for improving the stickiness of cooked rice, comprising the step of adding the stickiness improving composition described in claim 3 and cooking the rice.

10. A method for improving the graininess and granularity of cooked rice, comprising the step of adding a composition for improving graininess and granularity described in claim 4 and cooking the rice.

11. A method for improving the fluffiness of cooked rice, comprising the step of adding the fluffiness improving composition described in claim 6 and cooking the rice.

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