Composition and method for improving the loosening, flaky texture, graininess, hardness and / or oiliness of cooked rice, and method for producing cooked rice

Abstract

To provide a technique to improve looseness of cooked rice, and a technique to improve unstickiness, granularity, hardness and oiliness of cooked rice.SOLUTION: A composition for improving looseness of cooked rice includes lipase and / or a reduced starch syrup selected from the following (a)-(c) as an active ingredient: (a) a reduced starch syrup with its saccharide composition consisting of less than 30 mass% of monosaccharides and less than 50 mass% of polysaccharides with five or more sugar units, (b) a reduced starch syrup with its saccharide composition consisting of 50 mass% or more of polysaccharides with five or more sugar units, and (c) a reduced starch syrup prepared by reducing a starch syrup with a dextrose equivalent of 10 or more and 50 or less. This can improve looseness of cooked rice and also improve unstickiness, granularity, hardness and oiliness of cooked rice.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a composition for improving the loosening, flaky texture, graininess, hardness, and oiliness of cooked rice, which contains lipase and / or a specified reduced starch syrup as the active ingredient, and to a method for producing cooked rice using the composition. [Background technology]

[0002] When cooked rice is eaten as white rice with side dishes or in Japanese cuisine, a sticky or soft and fluffy texture is generally preferred. On the other hand, depending on the dish, particularly in Chinese and Western cuisine such as fried rice, pilaf, and risotto, a flaky or easy-to-break texture, a firm texture, or a firm grain texture may be preferred.

[0003] For example, fried rice served in restaurants has a light, flaky texture and the cooked rice separates easily. This texture is typically achieved by first heating oil and eggs in a pan, then using the eggs to create a thin film on the surface of the cooked rice, preventing the rice from sticking together. However, fried rice served in boxed lunches, chilled products, frozen foods, and the like is mass-produced in factories, where such cooking methods result in uneven heating, making it difficult to separate the cooked rice evenly. As a result, the light, flaky texture cannot be achieved, and clumps of rice that stick together reduce the heating efficiency during cooking and the cooling efficiency during the freezing process.

[0004] Therefore, research and development has been conducted into technologies for improving the loosening of cooked rice. For example, Patent Document 1 discloses a technology for making fried rice with a light and fluffy texture using a fried rice seasoning liquid containing salt, ethanol, and gelatin. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2011-120480 Summary of the Invention [Problem to be solved by the invention]

[0006] However, the technology described in Patent Document 1 requires procedures such as swelling of gelatin and heating and stirring, making the process complicated. Furthermore, the effects on graininess, hardness, and oiliness are unclear. In other words, even in light of the prior art, it cannot be said that there is a sufficient supply of simple technologies that can improve the loosening of cooked rice or the flaky texture, graininess, hardness, and oiliness of cooked rice. The present invention has been made to solve these problems, and aims to provide a technology that improves the loosening of cooked rice, and a technology that improves the loosening, graininess, hardness, and oiliness of cooked rice. [Means for solving the problem]

[0007] As a result of extensive research, the present inventors have found that lipase, low-sugar reduced starch syrup, and medium-sugar reduced starch syrup can improve the loosening, flaky texture, graininess, hardness, and oily texture of cooked rice. Based on this knowledge, the present inventors have completed the following inventions.

[0008] (1) The composition for improving the loosening properties of cooked rice according to the present invention contains, as an active ingredient, lipase and / or reduced starch syrup selected from the following (A) to (C): (A) Reduced starch syrup having a sugar composition of less than 30% by mass of monosaccharides and less than 50% by mass of 5 or more sugars (medium sugar content reduced starch syrup); (A) Reduced starch syrup having a sugar composition of 50% by mass or more of five sugars or more (low-sugar reduced starch syrup); (c) Reduced starch syrup (medium to low sugar content reduced starch syrup) obtained by reducing starch syrup with a dextrose equivalent of 10 to 50.

[0009] (2) The composition for improving the dryness, graininess, and / or hardness of cooked rice according to the present invention contains, as an active ingredient, lipase and / or reduced starch syrup selected from the following (A) to (C): (A) Reduced starch syrup having a sugar composition of less than 30% by mass of monosaccharides and less than 50% by mass of 5 or more sugars (medium sugar content reduced starch syrup); (A) Reduced starch syrup having a sugar composition of 50% by mass or more of five sugars or more (low-sugar reduced starch syrup); (c) Reduced starch syrup (medium to low sugar content reduced starch syrup) obtained by reducing starch syrup with a dextrose equivalent of 10 to 50.

[0010] (3) The composition for improving the oily texture of cooked rice cooked with oil according to the present invention contains, as an active ingredient, lipase and / or reduced starch syrup selected from the following (A) to (C): (A) Reduced starch syrup having a sugar composition of less than 30% by mass of monosaccharides and less than 50% by mass of 5 or more sugars (medium sugar content reduced starch syrup); (A) Reduced starch syrup having a sugar composition of 50% by mass or more of five sugars or more (low-sugar reduced starch syrup); (c) Reduced starch syrup (medium to low sugar content reduced starch syrup) obtained by reducing starch syrup with a dextrose equivalent of 10 to 50.

[0011] (4) In the present invention, the lipase may be a lipase having the following amino acid sequence (a) or (b): (a) an amino acid sequence in which any one of the amino acid mutations selected from those listed in Tables 1 to 5 below has been introduced into the amino acid sequence of SEQ ID NO: 1 (total length 269 amino acids); (b) An amino acid sequence having 90% or more sequence identity with (a), containing amino acid mutations corresponding to the amino acid mutations introduced in (a), and having lipase activity. [Table 1] [Table 2] [Table 3] [Table 4] [Table 5]

[0012] (5) The method for producing cooked rice according to the present invention comprises the step of adding the composition to rice before or during cooking, or to cooked rice after cooking. [Effects of the Invention]

[0013] According to the present invention, by the simple operation of adding an active ingredient before, during, or after cooking cooked rice, it is possible to improve the loosening of cooked rice, or to improve the flaky texture, graininess, hardness, and oiliness of cooked rice.

[0014] According to the present invention, the loosening of cooked rice can be improved, and cooked rice having a loose (crumbly) texture that crumbles easily when scooped with a spoon or put in the mouth can be obtained. As a result, cooked rice suitable for dishes where a loose texture is preferred, such as fried rice, fried rice, chicken rice, pilaf, paella, risotto, and curry rice, can be obtained.

[0015] According to the present invention, the graininess and hardness of cooked rice can be improved, and cooked rice with a firm texture in which the rice grains can be felt can be obtained. Therefore, cooked rice suitable for dishes in which a strong graininess and a hard texture are preferred, such as fried rice, fried rice, chicken rice, pilaf, paella, risotto, curry rice, and doria, can be obtained.

[0016] According to the present invention, the oily texture of cooked rice can be improved. As a result, cooked rice can be obtained that is tasty even when cooled, has little dryness when reheated, and is full of flavor and richness. Therefore, the taste of cooked rice dishes such as fried rice, fried rice, chicken rice, pilaf, paella, risotto, and butter rice can be improved or maintained. Furthermore, according to the present invention, it can be said that sufficient flavor and richness can be imparted to cooked rice dishes using oil with less oil. This can contribute to the production of healthy cooked rice foods that require less oil for cooking and have fewer calories. [Brief explanation of the drawings]

[0017] [Figure 1] Photographs showing the truncated cone shape and scattering of rice grains of fried rice containing low-sugar reduced starch syrup and / or lipase before and after dropping. [Figure 2] 1(I) shows the evaluation items and evaluation criteria of the sensory test, and FIG. 1(II) shows the evaluation sheet used in the sensory test. [Figure 3] 1 is a bar graph showing the evaluation score (average score) for each evaluation item in the sensory test. [Figure 4] 1 is a table showing the scores given by each panel in a sensory test. [Figure 5] This figure shows photographs of the cone-shaped state and scattered rice grains before and after dropping fried rice that was mixed with various types of reduced starch syrup or lipase and stored in a refrigerator, as well as the results of measuring the number of scattered grains and the evaluation results (comments) based on observation and tasting. [Figure 6] This figure shows photographs of the truncated cone shape and scattered rice grains before and after dropping fried rice that was mixed with various types of reduced starch syrup or lipase and stored frozen, as well as the results of measuring the number of scattered grains. DETAILED DESCRIPTION OF THE INVENTION

[0018] The present invention provides a "composition for improving the loosening properties of cooked rice," a "composition for improving the light and fluffy texture of cooked rice," a "composition for improving the graininess of cooked rice," a "composition for improving the hardness of cooked rice," and a "composition for improving the oily texture of cooked rice cooked with oil" (in the present invention, these compositions may be collectively referred to as "the composition," or any one of these compositions may be referred to as "the composition"), as well as a method for producing cooked rice (in the present invention, this may be referred to as "the method").

[0019] "Cooked rice" refers to cooked raw rice. Cooked rice may be unseasoned or may be seasoned in some way. Examples of seasoned cooked rice include fried rice, fried rice, chicken rice, pilaf, paella, risotto, butter rice, omelet rice, cooked rice, sushi, etc.

[0020] "Rice cooked with oil" refers to rice (including rice dishes, so-called "rice dishes") that has been prepared using edible oils and fats (including ingredients containing a lot of oils and fats) in the cooking process. Specific examples include pilaf, paella, risotto (usually prepared by frying raw rice in oil and fats and then cooking it, or by cooking rice in water containing oil and fats), butter rice (usually prepared by adding or mixing butter into cooked rice), fried rice, fried rice, and chicken rice (usually prepared by frying cooked rice in oil and fats).

[0021] "Rice cooking" refers to cooking raw rice, that is, the process of heating raw rice together with water until it is edible. In the present invention, the degree of polishing of the rice is not particularly limited, and it may be brown rice, white rice (polished rice), or polished rice such as 30-minute polished, 50-minute polished, or 70-minute polished rice.

[0022] "Fragmentation of cooked rice" refers to the degree to which rice grains adhere to each other in cooked rice. In other words, "cooked rice that is easy to disintegrate" means that the degree to which rice grains adhere to each other is small, making the rice grains easy to separate, or that the external force required to separate the rice grains is small. Also, "improving the fragility of cooked rice" means reducing the degree to which rice grains adhere to each other, making them easy to separate.

[0023] Whether or not the loosening of cooked rice has improved can be confirmed, for example, by filling a cup with cooked rice X using the present composition and cooked rice Y not using the present composition, molding them under pressure, then removing the cup and subjecting it to a drop test as shown in the Examples below. If the comparison results show that cooked rice X loses its shape to a greater extent or that more rice grains are scattered than cooked rice Y, it can be determined that the loosening of cooked rice has been improved by the present composition.

[0024] The "crunchy texture of cooked rice" refers to the sensation of rice grains coming apart (loosening) when external force is applied to cooked rice (a collection of rice grains) (for example, when scooping cooked rice with chopsticks, a spoon or other utensil, when putting cooked rice in the mouth, when chewing cooked rice, etc.). In other words, "a strong crunchy texture" refers to the sensation that the rice grains easily come apart and fall apart when external force is applied. Furthermore, "improving the crunchiness of cooked rice" means making the rice grains easily come apart when external force is applied to the cooked rice. Therefore, it can be said that the crunchiness can be improved by improving the loosening of cooked rice. In the present invention, the crunchiness that is particularly felt in the mouth is referred to as the "crunchy texture."

[0025] "Rice grain texture" refers to the sensation of rice grains felt when putting cooked rice in the mouth or chewing. When the grain texture is felt, the rice is less likely to be crushed in the mouth and each grain can be felt clearly. "Improving the grain texture" means making the sensation of rice grains felt in the mouth stronger (making the sensation of the grains more clearly felt).

[0026] "Oily feel of cooked rice" refers to the sense of oily taste (richness and flavor) and aroma felt when putting cooked rice in the mouth or chewing it. In other words, "improving the oily feel" means making the oily taste and aroma felt in the mouth stronger (making the oily taste and aroma more clearly felt).

[0027] In the present invention, whether or not the "dried texture," "grainy texture," "hardness," or "oily texture" of cooked rice has been improved can be confirmed, for example, by conducting a sensory test using texture or oily texture as an evaluation item for cooked rice X prepared using the present composition and cooked rice Y not prepared using the present composition, and comparing the results. If the comparison results show that cooked rice X has a "stronger dried texture," "a more grainy texture," "harder," or "stronger oiliness" than cooked rice Y, it can be determined that the composition has improved the texture or oily texture.

[0028] This composition contains lipase, medium-sugar reduced starch syrup, and / or low-sugar reduced starch syrup as active ingredients. Lipase is an enzyme that catalyzes the reaction of hydrolyzing glycerol esters (neutral fats, triglycerides) into fatty acids and glycerol. In the present invention, the lipase may be a commercially available lipase preparation, and examples of such commercially available products include "Lipase AY Amano 30SD," "Lipase A Amano 6," "Lipase GS Amano 250G," "Lipase R Amano," "Lipase MHA Amano 10SD," "Lipase DF Amano 15," "Lipase MER Amano," and "Neurase F3G" (all Amano Enzyme), "Sumiteam NLS," and "Sumiteam MML-G" (all Shin Nippon Chemical Industry), "Lipase-MY," "Lipase-OF," "Lipase-PL," and "Lipase-QLM" (all Meito Sangyo), "Lipase A-10D" (Nagase ChemteX), "SpicelT AC" (Christian Hansen), "Paratase," "Lipozyme," "Lipopan," "Lipopan Prime," and "Lecitase" (all Novozymes), "BAKEZYME L80000," and "PICCANTASE." Examples include "R800", "PICCANTASE A" (both DSM Food Specialties), "Biolopase" and "Biobake CRUMB" (both Kerry I&F Cork / Ireland).

[0029] It is also known that some lipases have not only triglyceride decomposition activity (lipase activity) but also phospholipid decomposition activity (phospholipase activity) and digalactosyldiglyceride decomposition activity (DGDG decomposition activity) (Japanese Patent No. 4723087; Examples 5 and 13). 16 ~C 20 It is known that there are lipases that have high decomposition activity for long-chain triglycerides, which are long-chain fatty acid esters of DGDG (Japanese Patent No. 4723087; Examples 5 and 7). In the present invention, such lipases having phospholipase activity, lipases having DGDG decomposition activity, or lipases having high decomposition activity for long-chain triglycerides can be preferably used.

[0030] Specific examples of lipases having phospholipase activity include those having the following amino acid sequence (a) or (b): (a) an amino acid sequence in which any one of the amino acid mutations selected from those listed in Tables 1 to 5 above has been introduced into the amino acid sequence of SEQ ID NO: 1 (total length 269 amino acids); (b) An amino acid sequence having 90% or more sequence identity with (a), containing amino acid mutations corresponding to the amino acid mutations introduced in (a), and having lipase activity.

[0031] Here, SEQ ID NO: 1 is the amino acid sequence of a lipase from the filamentous fungus Humicola lanuginosa strain DSM 4109 (hereinafter, sometimes referred to as "DSM4109 lipase"). Therefore, a lipase having the amino acid sequence (a) refers to a mutant lipase in which any one of the 129 amino acid mutations listed in Tables 1 to 5 has been introduced into DSM4109 lipase. Furthermore, a lipase having the amino acid sequence (b) refers to a mutant lipase that is highly similar to (a) in terms of amino acid sequence and enzymatic activity.

[0032] SEQ ID NO: 1 is equivalent to the amino acid sequence from positions 1 to 269 of SEQ ID NO: 2 described in U.S. Patent No. 5,869,438. The 129 types of amino acid mutations described in Tables 1 to 5 are equivalent to the amino acid mutations described in Tables 1 to 5 described in the Claims section of Japanese Patent No. 4,723,087 or Tables 6 to 11 described in the Detailed Description of the Invention of the same patent.

[0033] In the present invention, the lipase activity and phospholipase activity can be confirmed by a conventional method, for example, by the following method. Lipase activity The substrate is prepared by emulsifying tributyrin (glycerol tributyrate) with gum arabic (emulsifier). Hydrolysis of this substrate is carried out at 30°C and pH 7, and the release of butyric acid is followed by pH-stat titration. One unit of lipase activity (1 LU) is the amount of enzyme that will liberate 1 μmole of butyric acid per minute under these conditions. One KLU is the amount of enzyme that will liberate 1 mmol of butyric acid per minute under these conditions.

[0034] <Phospholipase activity> Phospholipase activity (PHLU) was measured using lecithin as a substrate. 50 μL of diluted lipase sample was added to 50 μL of a buffer solution (50 mM HEPES buffer containing 4% Triton X-100 and 5 mM calcium chloride) containing 4% L-alpha-phosphatidylcholine (vegetable lecithin, Avanti) as a substrate. Hydrolysis of the substrate was carried out at 30°C, pH 7 for 10 minutes. The reaction was stopped by incubation at 95°C for 5 minutes and then centrifuged at 7000 rpm for 5 minutes. Subsequently, after reaction with Reagent A and Reagent B of the NEFA C kit (Wako Chemicals), free fatty acids were measured by measuring the absorbance at 550 nm using an HP 8452A diode array spectrophotometer. Oleic acid was used as a standard sample. One PHLU is the amount of enzyme that liberates 1 μmole of fatty acid per minute under these conditions.

[0035] The definitions of the amino acid mutations listed in Tables 1 to 5 are as follows. Amino acids are represented by single-letter abbreviations. For example, G91A indicates a substitution of A (alanine) for G (glycine) at position 91. For example, T267A,Q indicates a substitution of A or Q (glutamine) for T (threonine) at position 267. E1E,D,A indicates that E (glutamic acid) at position 1 is either retained or substituted with D (aspartic acid) or A. T267stop indicates a stop codon. This indicates the deletion of all amino acids downstream of position 267 (toward the carboxyl terminus) (i.e., T267, C268, and L269). 270P,271V indicates an extension of PV toward the carboxyl terminus (i.e., at new positions 270 and 271). -G266 indicates the deletion of G at position 266. Parentheses indicate that the change is optional. SPIRR indicates an N-terminal extension. D266 indicates a substitution of any amino acid except D at position 266. E1SPPCGRRP indicates a substitution of SPPCGRRP for E at position 1, i.e., a peptide addition at the amino terminus. T267GS indicates a substitution of GS for T at position 267, or in other words, the substitution T267G and the insertion of S between G267 and G268.

[0036] 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). Note that "identity" refers to consistency and is used interchangeably with "identity."

[0037] The mutant lipase can be obtained by a conventional method, such as chemical synthesis or genetic recombination. For example, the mutant lipase can be synthesized based on the amino acid sequence information (a) or (b) above by chemical synthesis methods such as the Fmoc method (fluorenylmethyloxycarbonyl method) or the tBoc method (t-butyloxycarbonyl method), or can also be synthesized using various commercially available peptide synthesizers.

[0038] Alternatively, in a method using genetic recombination technology, the variant lipase may be expressed in a suitable expression system. Specifically, DNA encoding the amino acid sequence of the variant lipase is inserted into an appropriate vector to obtain a recombinant vector, which is then introduced into a suitable host to obtain a transformant. The resulting transformant is then cultured to express the variant lipase. The DNA encoding the amino acid sequence of the variant lipase can be synthesized using various commercially available DNA synthesizers based on the nucleotide sequence information, or it can be obtained by polymerase chain reaction (PCR) using DNA encoding DSM4109 lipase as a template.

[0039] In the present invention, the unit of enzymatic activity of lipase is defined as 10 U, which is the amount of enzyme that liberates 1 μmole of fatty acid per minute when allowed to act on olive oil emulsion as a substrate for 30 minutes at 37°C and pH 6.0.

[0040] Reduced starch syrup is a type of sugar alcohol obtained by reducing starch syrup. Here, starch syrup is a substance obtained by saccharifying starch with acids or enzymes, and is a mixture of monosaccharides (glucose) and polysaccharides (oligosaccharides, dextrin, 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 than pentasaccharides).

[0041] Reduced starch syrup can be divided into high saccharification reduced starch syrup, medium saccharification reduced starch syrup, and low saccharification reduced starch syrup depending on the degree of saccharification. Of these, it is preferable to use medium saccharification reduced starch syrup and / or low saccharification reduced starch syrup in the present invention.

[0042] Specific examples of the sugar composition of medium-sugar reduced starch syrup include (a) a sugar composition containing less than 30% by mass of monosaccharides and less than 50% by mass of pentasaccharides or more, or (d) a sugar composition containing 2 to 10% by mass of monosaccharides, 15 to 55% by mass of disaccharides, 15 to 65% by mass of trisaccharides, 1 to 15% by mass of tetrasaccharides, and 1 to 38% by mass of pentasaccharides or more.

[0043] Specific examples of the sugar composition of low-saccharification reduced starch syrup include (i) a sugar composition containing 50% by mass or more of pentasaccharides, or (e) a sugar composition containing 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.

[0044] 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.

[0045] The sugar composition can be confirmed using high performance liquid chromatography (HPLC). That is, reduced starch syrup 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: MCI GEL CK04S (10mm ID x 200mm) Eluent; high purity water Flow rate; 0.4mL / min Injection volume: 20μL Column temperature: 65°C Detection: Differential refractive index detector RI-10A (Shimadzu Corporation)

[0046] Since 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. The 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 solids when the reducing sugars in the sample are measured as glucose. The maximum DE value is 100, which means that all of the solids are glucose, and the lower the DE, the more oligosaccharides and polysaccharides there are.

[0047] That is, the DE of the raw material starch syrup for medium sugar content reduced starch syrup can be exemplified as more than 30, 31 or more, 32 or more, 45 or less, 46 or less, 47 or less, 48 ​​or less, 49 or less, and 50 or less.

[0048] Furthermore, examples of the DE of the raw material starch syrup for low sugar reduced starch syrup include 10 or more, 11 or more, 12 or more, 13 or more, 14 or more, and 30 or less.

[0049] Furthermore, examples of the DE of the raw material starch syrup for medium to low sugar reduced starch syrup include (c) 10 or more and 50 or less.

[0050] 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.

[0051] In the present invention, commercially available reduced starch syrup may be used as is, or may be produced according to methods known to those skilled in the art. Examples of commercially available medium-sugar reduced starch syrup include "Sweet OL," "Sweet G3," "SE 57," and "SE 58" (all from Bussan Food Science), and examples of commercially available low-sugar reduced starch syrup include "Sweet NT," "SE 30," and "SE 100" (all from Bussan Food Science).

[0052] A known method for producing reduced starch syrup is a reduction reaction in which hydrogen is added to starch syrup (raw material sugar). The reduction reaction by hydrogen addition can be carried out, for example, by charging a 40 to 75% by mass aqueous solution of raw material 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, and the reaction solution temperature to 70 to 180°C, while mixing and stirring, until hydrogen absorption is no longer observed. The reduction catalyst is then separated, and the resulting 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.

[0053] Lipase and / or reduced starch syrup can be used as a single ingredient in the process of producing cooked rice, similar to other seasonings and additives. For example, it can be used in the following ways: (i) by adding it to rice or the water in which the rice is soaked before or during cooking, (ii) by adding it together with other seasonings when seasoning the cooked rice, or (iii) by adding it when cooking the cooked rice, such as by frying. When lipase and reduced starch syrup are used together, they may be added at the same time or at different times.

[0054] That is, the method for producing cooked rice according to the present invention comprises a step of adding the composition to rice before or during cooking, or to cooked rice after cooking. The method may include other steps as long as the features of the present invention are not impaired. Examples of such steps include a step of mixing food ingredients, a step of frying, a step of seasoning, a step of forming, a step of cooling, a step of packaging, a step of sterilizing, a step of freezing, etc.

[0055] The amount of lipase to be added (amount added) can be determined appropriately depending on the type of rice, the desired texture, the dish, the flavor, the presence, type, and amount of secondary ingredients, etc. A specific amount to be added can be, for example, 0.1 to 50 kilolipase units (KLU) of lipase per 100 parts by weight of rice.

[0056] The amount of reduced starch syrup added (amount added) can also be set appropriately depending on the type of rice, desired texture, dish item, flavor, the presence / absence, type, and amount of secondary ingredients, etc. Specific examples of the amount added include a lower limit of 0.1 parts by weight or more, 0.15 parts by weight or more, 0.2 parts by weight or more, 0.25 parts by weight or more, 0.3 parts by weight or more, and 0.35 parts by weight or more per 100 parts by weight of rice. Examples of the upper limit of reduced starch syrup include 10 parts by weight or less, 9.5 parts by weight or less, 9 parts by weight or less, 8.5 parts by weight or less, 8 parts by weight or less, 7.5 parts by weight or less, and 7 parts by weight or less per 100 parts by weight of rice.

[0057] The present invention will be described below based on examples, but the technical scope of the present invention is not limited to the features shown in these examples. [Example]

[0058] <Test Method> (1) Improver Lipase and reduced starch syrup were used as improvers. The lipase used was a mutant lipase (commercial product: 10 KLU / g) in which one of the 129 amino acid mutations listed in Tables 1 to 5 was introduced into DSM4109 lipase. The reduced starch syrup used was a commercially available product listed in Table 6. [Table 6]

[0059] (2) Making fried rice To make fried rice, follow these steps: <1> ~ <4> It was produced by <1> Water, lipase and / or reduced starch syrup were added to washed rice and the rice was soaked for 1 hour. The amount of each substance added (the amount of soaking water) is shown in each example. <2> The rice was cooked in a rice cooker to make cooked rice. <3> 250g of cooked rice was mixed with 50g of beaten egg and fried for 1 minute in a frying pan with 15g of salad oil at 150°C. <4> 8g of powdered seasoning for fried rice (commercially available) <3> In addition, stir-fry for another 2 minutes and 30 seconds to make fried rice.

[0060] (3) Drop test 50g of fried rice filled in a round cup was placed on a paper plate placed on a tray, with the lid removed and the cup turned upside down. The cup was then removed, and the paper plate with the truncated cone-shaped fried rice, along with the tray, was dropped once from a height of approximately 10cm or five times from a height of approximately 30cm while held horizontally. Photographs were taken before and after the drop, and the extent to which the truncated cone had collapsed and the state of scattered rice grains were observed after the drop. In addition, rice grains or clusters of rice grains located away from the cluster of rice grains where the cup was removed were considered "scattered rice grains," and the number of such grains (scattered rice count) was counted. Three samples were set up for each test plot, and the average number of scattered rice grains was calculated.

[0061] Example 1: Evaluation of ease of loosening Fried rice (samples 1 to 4) was prepared using the soaking water composition shown in Table 7 according to test method (2). Low-sugar reduced starch syrup (SE 30) was used as the reduced starch syrup. The prepared fried rice was spread on a tray and left at room temperature for 1 hour to cool. Then, 50 g of fried rice was filled into round cups, which were then covered and left at room temperature for 5 hours. The samples were then subjected to the drop test according to test method (3), and the scattering of rice grains was observed. The drop condition was "one drop from a height of approximately 10 cm." The results are shown in Figure 1. [Table 7]

[0062] As shown in Figure 1, Sample 2 (low-glycerol reduced starch syrup), Sample 3 (lipase), and Sample 4 (lipase + low-glycerol reduced starch syrup) all showed a greater degree of crumbling into a truncated cone shape than Sample 1 (no improver). In other words, fried rice made with cooked rice that had been mixed with low-glycerol reduced starch syrup and / or lipase had rice grains that were easier to separate than rice that had not been mixed with these improvers. These results demonstrate that low-glycerol reduced starch syrup and lipase can improve the ease of separating cooked rice.

[0063] Example 2: Evaluation of texture and taste A sensory test of texture and taste was conducted by three analytical panelists (Classes A to C) who ate the fried rice from Samples 1 to 4 used in the drop test in Example 1. The evaluation items, evaluation criteria, and evaluation sheet used in the sensory test are shown in Figure 2.

[0064] As shown in Figure 2, the evaluation items were "crispy texture," "grainy texture," "hardness," "oily texture," and "overall evaluation." The evaluation criteria were as follows: Sample 1 (without improver) was given a score of 3, and each panelist scored the samples in 0.5-point increments between 1 and 5 points according to the following criteria. "Crispy texture" 5 points: very strong (prominent) crunchiness, 4 points: strong crunchiness, 3 points: same as sample 1, 2 points: weak crunchiness, 1 point: no crunchiness felt. "Graininess" 5 points: graininess is clearly felt, 4 points: graininess is felt, 3 points: same as sample 1, 2 points: graininess is weak, 1 point: graininess is not felt. "Hardness" 5 points: obviously hard, 4 points: somewhat hard, 3 points: equivalent to sample 1, 2 points: somewhat soft, 1 point: obviously soft. "Oily feeling" 5 points: very oily feeling, 4 points: very oily feeling, 3 points: same as sample 1, 2 points: weak oily feeling, 1 point: very weak oily feeling. "Overall rating" 5 points: very good fried rice, 4 points: good fried rice, 3 points: same as sample 1, 2 points: not good fried rice, 1 point: not good fried rice.

[0065] In other words, the higher the score for each evaluation item, the better. The scoring results were calculated by calculating the average score for each sample from all panels and rounding off to the nearest tenth. The scores (average scores) are shown in Figure 3, and the scores for each panel are shown in Figure 4.

[0066] As shown in Figures 3 and 4, Sample 2 (low-sugar reduced starch syrup) received higher scores for "crispy texture," "grainy texture," "hardness," and "overall evaluation" compared to Sample 1 (no improving agent), and the "oily texture" was comparable. In other words, it was revealed that fried rice made with cooked rice that had been blended with low-sugar reduced starch syrup had a better texture (crispy texture, grainy texture, and hardness) and was superior in taste compared to fried rice that had not been blended with low-sugar reduced starch syrup.

[0067] Next, sample 3 (lipase) received higher scores for "crispy texture," "grainy texture," "hardness," "oily texture," and "overall evaluation" compared to sample 1. In other words, it was revealed that fried rice made with cooked rice that had been blended with lipase had a better texture (crispy texture, grainy texture, and hardness), a stronger oily texture, and an excellent taste compared to fried rice made without lipase.

[0068] Furthermore, sample 4 (low-glycerol reduced starch syrup and lipase) received higher scores for "crispy texture," "grainy texture," "hardness," "oily texture," and "overall evaluation" compared to sample 1. In other words, it was revealed that fried rice made with cooked rice that had been blended with low-glycerol reduced starch syrup and lipase had a better texture (crispy texture, grainy texture, and hardness), a stronger oily texture, and excellent taste compared to fried rice made without these improvers.

[0069] These results demonstrate that low-glycemic reduced starch syrup and lipase can improve the texture of cooked rice (crumbly texture, granular or grainy texture, hardness). They also demonstrate that low-glycemic reduced starch syrup and lipase can improve the oily texture of cooked rice with oil.

[0070] Example 3: Evaluation of the ease of loosening of refrigerated fried rice Fried rice samples (samples 1 to 5) were prepared using the soaking water composition shown in Table 8 according to test method (2). High-sugar reduced starch syrup, low-sugar reduced starch syrup (SE 30), and low-sugar reduced starch syrup (SE 100) were used as reduced starch syrup. 50 g of the prepared fried rice was filled into round cups, covered, and placed in a refrigerator at approximately 4°C for overnight storage. The samples were then subjected to the drop test according to test method (3), and the degree of crumbling of the truncated cone and the state of scattered rice grains were observed, along with the number of scattered grains. The drop condition was "five times from a height of approximately 30 cm." Each sample was also tasted to confirm its texture. The results are shown in Figure 5. [Table 8]

[0071] As shown in Figure 5, sample 2 (highly saccharified reduced starch syrup) had a harder texture than sample 1 (no improver), but the degree of crumbling into the truncated cone shape was small and the number of scattered grains was also small. In contrast, samples 3 and 4 (lowly saccharified reduced starch syrup) had a slightly greater degree of crumbling into the truncated cone shape and a greater number of scattered grains than sample 1. Furthermore, samples 3 and 4 had a hard texture, good grain structure, and the rice grains easily separated in the mouth. Sample 5 (lipase) also had a greater degree of crumbling into the truncated cone shape and a greater number of scattered grains than sample 1. The texture of sample 5 was the hardest of samples 1 to 5, with a more granular feel and the rice grains most easily separated in the mouth.

[0072] That is, fried rice made with cooked rice that had been blended with low-sugar reduced starch syrup and / or lipase had rice grains that were easier to separate, had a harder texture, and felt more granular, even when stored refrigerated, compared to rice that had not been blended with these improving agents. These results demonstrate that low-sugar reduced starch syrup and lipase can improve the separation of cooked rice, as well as the texture of cooked rice (crumbly texture, granularity or graininess, and hardness).

[0073] Example 4: Evaluation of the ease of loosening of frozen fried rice Fried rice samples (samples 1 to 6) were prepared using the soaking water formulations shown in Table 9 according to test method (2). The reduced starch syrup used was medium-sugar reduced starch syrup, low-sugar reduced starch syrup (Sweet NT), low-sugar reduced starch syrup (SE 30), and low-sugar reduced starch syrup (SE 100). Each 100g portion of the prepared fried rice was wrapped in plastic wrap and frozen at -20°C for 5 days. The frozen fried rice was then heated in a 600-watt microwave oven for 2 minutes. 50g portions of the fried rice were filled into round cups, covered, and refrigerated overnight at approximately 4°C. The samples were then subjected to the drop test according to test method (3). The degree of collapse of the truncated cone and the degree of scattered rice grains were observed, and the number of scattered grains was counted. The results are shown in Figure 6. [Table 9]

[0074] As shown in Figure 6, Sample 2 (medium-sugar reduced starch syrup) showed a slightly greater degree of cone-shaped crumbling and a greater number of scattered grains than Sample 1. Samples 3 (low-sugar reduced starch syrup: Sweet NT), 4 (low-sugar reduced starch syrup: SE 30), 5 (low-sugar reduced starch syrup: SE 100), and 6 (lipase) all showed a greater degree of cone-shaped crumbling and a significantly greater number of scattered grains than Sample 1. In other words, fried rice made with cooked rice containing medium-sugar reduced starch syrup, low-sugar reduced starch syrup, and / or lipase had rice grains that were easier to separate than rice without these improving agents, even when frozen. These results demonstrate that medium-sugar reduced starch syrup, low-sugar reduced starch syrup, and lipase can improve the ease of separating cooked rice.

[0075] From the results of Examples 1, 3 and 4 above, it was revealed that medium-sugar reduced starch syrup, low-sugar reduced starch syrup and lipase can improve the loosening of cooked rice after cooking, refrigerated storage and frozen storage.

Claims

1. A composition for improving the loosening properties of cooked rice, the composition comprising one or more active ingredients selected from the following (A) to (E): (A) reduced starch syrup having a sugar composition of 50% by mass or more of five sugars; (B) reduced starch syrup obtained by reducing starch syrup having a dextrose equivalent of 10 to 30; (C) reduced starch syrup having a sugar composition of less than 30% by mass of monosaccharides and less than 50% by mass of pentasaccharides or more; (D) reduced starch syrup obtained by reducing starch syrup having a dextrose equivalent of more than 30 and less than 50; (E) Lipase.

2. A composition for improving the dryness, graininess and / or hardness of cooked rice, the composition comprising one or more active ingredients selected from the following (A) to (E): (A) reduced starch syrup having a sugar composition of 50% by mass or more of five sugars; (B) reduced starch syrup obtained by reducing starch syrup having a dextrose equivalent of 10 to 30; (C) reduced starch syrup having a sugar composition of less than 30% by mass of monosaccharides and less than 50% by mass of pentasaccharides or more; (D) reduced starch syrup obtained by reducing starch syrup having a dextrose equivalent of more than 30 and less than 50; (E) Lipase.

3. A composition for improving the oily texture of cooked rice, the composition comprising one or more active ingredients selected from the following (A) to (E): (A) reduced starch syrup having a sugar composition of 50% by mass or more of five sugars; (B) reduced starch syrup obtained by reducing starch syrup having a dextrose equivalent of 10 to 30; (C) reduced starch syrup having a sugar composition of less than 30% by mass of monosaccharides and less than 50% by mass of pentasaccharides or more; (D) reduced starch syrup obtained by reducing starch syrup having a dextrose equivalent of more than 30 and less than 50; (E) Lipase.

4. The composition according to any one of claims 1 to 3, wherein the lipase has the following amino acid sequence (a) or (b): (a) an amino acid sequence in which any one of the amino acid mutations selected from those listed in Tables 1 to 5 below has been introduced into the amino acid sequence of SEQ ID NO: 1 (total length 269 amino acids); (b) An amino acid sequence having 90% or more sequence identity with (a), having amino acid mutations corresponding to the amino acid mutations introduced in (a), and having lipase activity. 【Table 1】 【Table 2】 【Table 3】 【Table 4】 【Table 5】

5. A composition described in any one of claims 1 to 3, characterized in that it uses one or more reduced starch syrups selected from (A) to (D) in combination with (E) lipase.

6. A method for improving the loosening of cooked rice, comprising the step of adding one or more selected from the following (A) to (E) to rice before or during cooking, or to cooked rice after cooking: (A) reduced starch syrup having a sugar composition of 50% by mass or more of five sugars; (B) reduced starch syrup obtained by reducing starch syrup having a dextrose equivalent of 10 to 30; (C) reduced starch syrup having a sugar composition of less than 30% by mass of monosaccharides and less than 50% by mass of pentasaccharides or more; (D) reduced starch syrup obtained by reducing starch syrup having a dextrose equivalent of more than 30 and less than 50; (E) Lipase.

7. A method for improving the fluffiness, graininess, and / or hardness of cooked rice, comprising the step of adding one or more selected from the following (A) to (E) to rice before or during cooking, or to cooked rice after cooking: (A) reduced starch syrup having a sugar composition of 50% by mass or more of five sugars; (B) reduced starch syrup obtained by reducing starch syrup having a dextrose equivalent of 10 to 30; (C) reduced starch syrup having a sugar composition of less than 30% by mass of monosaccharides and less than 50% by mass of pentasaccharides or more; (D) reduced starch syrup obtained by reducing starch syrup having a dextrose equivalent of more than 30 and less than 50; (E) Lipase.

8. A method for improving the oily texture of cooked rice using oil, comprising the step of adding one or more selected from the following (A) to (E) to rice before or during cooking, or to cooked rice after cooking: (A) reduced starch syrup having a sugar composition of 50% by mass or more of five sugars; (B) reduced starch syrup obtained by reducing starch syrup having a dextrose equivalent of 10 to 30; (C) reduced starch syrup having a sugar composition of less than 30% by mass of monosaccharides and less than 50% by mass of pentasaccharides or more; (D) reduced starch syrup obtained by reducing starch syrup having a dextrose equivalent of more than 30 and less than 50; (E) Lipase.

9. A method for producing cooked rice, comprising the step of adding the composition according to any one of claims 1 to 5 to rice before or during cooking, or to cooked rice after cooking.

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