Rice cooking method and the flavor-enhancing and preservative agent used for cooked rice.

Abstract

To obtain a production method of cooked rice which has excellent flavor and no acetic acid odor or acid taste when just being cooked, has a high yield and good preservability, and revives flavor not inferior to flavor when just being cooked due to microwaving with a microwave oven after preservation in a cold place, including adding special preparation for flavor improvement deterioration prevention for cooked rice to raw rice followed by cooking, and to obtain the preparation for flavor improvement deterioration prevention for cooked rice.SOLUTION: A rice cooking method includes adding to raw rice, 1-3.5 wt.% of preparation for flavor improvement deterioration prevention for cooked rice, containing 1.0-18.2 wt.% of acetic acid, 3.3-45.0 wt.% of reduced starch hydrolyzate, 3.3-45.0 wt.% of reducing sugar, and 0-17 wt.% of salt to 130-185 wt.% of water of the raw rice when cooking rice.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a method for producing cooked rice, in which a flavor improvement and deterioration prevention agent is added to raw rice among foods, and the cooked rice has a good flavor when cooked, a high water yield, good storage stability, and can restore a flavor comparable to that at the time of cooking immediately by range-up after cold storage, and to a flavor improvement and deterioration prevention agent for the cooked rice.

Background Art

[0002] Many additives are used in bento boxes, rice balls, etc. sold in supermarkets, convenience stores, etc. for the purpose of improving shelf life and texture. Among them, the recent needs for cooked rice are to have a long shelf life without affecting the taste, be difficult to age even at low temperatures, have a good water yield and be economical, maintain a deliciousness close to that of freshly cooked rice for a long time after range-up, and not inhibit the original taste of the original recipe.

[0003] Among these, a method for producing cooked rice that can impart a flavor equivalent to that of conventional cooked rice flavored after cooking and suppress the generation of cores, a seasoning liquid used in the method, and a method for suppressing the cores of cooked rice (Patent Document 1), or a mixture obtained by mixing a low-decomposed starch having a specific molecular weight and a dextrin having a specific DE value at a specific mass ratio and adding it to cooked rice, resulting in cooked rice with significantly improved flavor and / or its persistence (Patent Document 2), a combined vinegar mainly composed of vinegar, saccharides, salt, and a high-intensity sweetener, which has a lower calorie and can reduce costs compared to conventional ones, and does not impair the flavor and texture when mixed with cooked rice to make sushi rice (Patent Document 3), etc. Although the descriptions in the prior art documents are all for sushi rice, the cooked rice of the present application is targeted at plain rice or colored rice without a sour taste or vinegar smell. The preparations for sushi rice have a strong sour taste and sweetness in the cooked rice, which are too strong in sourness and sweetness for other cooked rice except sushi rice.

Prior Art Documents

Patent Documents

[0004] [Patent Document 1] Patent No. 6842075 [Patent Document 2] Japanese Patent Publication No. 2017-077223 [Patent Document 3] Japanese Patent Publication No. 2010-29175 [Disclosure of the Invention] [Problems that the invention aims to solve]

[0005] The object of the present invention is to provide a method for producing cooked rice in which, by adding a rice flavor-improving and deterioration-preventing agent during cooking, the cooked rice has a good flavor, is free from acetic acid odor and sourness, has a high moisture yield (even when using more cooking water than the standard amount, the cooked rice does not become sticky and has a good texture), has good shelf life, and when reheated in a microwave oven after being stored in a cool place, the flavor is restored to a level comparable to that of freshly cooked rice, and to provide a rice flavor-improving and deterioration-preventing agent. [Means for solving the problem]

[0006] As a result of diligent research, the inventors have discovered that by adding or incorporating 1 to 3.5% by weight of a rice flavor-improving and preservative agent, which contains 1.0 to 18.2% by weight of acetic acid, 3.3 to 45.0% by weight of reduced starch hydrolysate, and 3.3 to 45.0% by weight of reducing sugar, and optionally salt, to 130 to 185% by weight of water relative to the raw rice during cooking, it is possible to obtain cooked rice that is free from acetic acid odor and sourness, has good flavor, high shelf life, high yield, is less susceptible to aging during storage, and exhibits excellent texture reproduction after microwave heating. This invention was completed based on this finding. In other words, the present invention is 1. A method for producing cooked rice, in which, during cooking, 1.0 to 3.5% by weight of a rice flavor enhancer and preservative, comprising 1.0 to 18.2% by weight of acetic acid, 3.3 to 45.0% by weight of reduced starch hydrolysate, 3.3 to 45.0% by weight of reducing sugar, and 0 to 17.0% by weight of salt, is added to 130 to 185% by weight of water relative to the raw rice, and the rice is then cooked. 2. The method for producing cooked rice according to claim 1, wherein the flavor-improving and spoilage-preventing agent for cooked rice contains 1.4 to 15.6% by weight of acetic acid, 6.6 to 40.0% by weight of reduced starch hydrolysate, 6.6 to 40.0% by weight of reducing sugar, and 5 to 14% by weight of salt. 3. A flavor enhancer and spoilage inhibitor for cooked rice, containing 1.0-18.2% by weight of acetic acid, 3.3-45.0% by weight of hydrolyzed reduced starch, 3.3-45.0% by weight of reducing sugar, and 0-17% by weight of salt. 4. The flavor-improving and spoilage-preventing agent for cooked rice according to claim 3, comprising 1.4 to 15.6% by weight of acetic acid, 6.6 to 40.0% by weight of reduced starch hydrolysate, 6.6 to 40.0% by weight of reducing sugar, and 5 to 14% by weight of salt. That is the case. [Effects of the Invention]

[0007] The acetic acid used in this invention can be any edible vinegar, and can be either brewed vinegar or synthetic vinegar. Examples of brewed vinegars include black vinegar, rice vinegar, grain vinegar, apple vinegar, grape vinegar, fruit vinegar, and brewed vinegar. Among these, synthetic vinegar or brewed vinegar (brewed vinegar that is neither grain vinegar nor fruit vinegar) with less sweetness and a stronger flavor are preferred, and natural brewed vinegar (brewed vinegar that is neither grain vinegar nor fruit vinegar) is even more preferred. It can also be used in liquid or powder form. In this invention, powdered vinegar can also be used, which is prepared by dissolving reduced starch hydrolysate in water with brewed vinegar and then adjusting the acidity to the desired level by spray drying.

[0008] The proportion of acetic acid in the flavor-improving and preservative agent for cooked rice used in the present invention (sometimes referred to as a formulation) is 1.0 to 18.2% by weight, preferably 1.4 to 15.6% by weight, relative to the total amount of formulation components. The range of acetic acid added to raw rice during cooking is 0.036 to 0.182% by weight, preferably 0.044 to 0.156% by weight.

[0009] The reduced starch hydrolysates used in this invention are classified into high-saccharification reduced starch syrup, medium-saccharification reduced starch syrup, low-saccharification reduced starch syrup, etc., depending on their degree of saccharification, and any of them can be used, but for cooked rice, it is preferable to use one with as little sweetness as possible. That is, medium-saccharification reduced starch syrup and low-saccharification reduced starch syrup are preferred, and low-saccharification reduced starch syrup is more preferred.

[0010] In the present invention, the proportion of reduced starch hydrolysate in the total formulation is 3.3 to 45.0% by weight, preferably 6.6 to 40.0% by weight, and more preferably 11.0 to 33.3% by weight, in the case of a liquid formulation. The proportion of reduced starch hydrolysate to raw rice during cooking is 0.033 to 1.575% by weight, preferably 0.066 to 1.400% by weight, and more preferably 0.11 to 1.166% by weight.

[0011] In the present invention, the sweetness levels of reduced starch hydrolysates are as follows, with sugar set to 1: high-saccharification reduced starch syrup is 0.6-0.7, medium-saccharification reduced starch syrup is 0.4-0.5, and low-saccharification reduced starch syrup is 0.1-0.3. However, the sweetness level of "H-Pinedix" manufactured by Matsutani Chemical Industry Co., Ltd., used in the examples is 0.17.

[0012] The reducing sugars used in the present invention are specifically palatinite, erythritol, lactitol, sorbitol, maltitol, etc., but palatinite, erythritol, and more preferably palatinite.

[0013] In the present invention, the proportion of reducing sugar in the formulation is 3.3 to 45.0% by weight, preferably 6.6 to 40.0% by weight, and more preferably 11.0 to 33.3% by weight, relative to the total formulation in the case of a liquid formulation. The proportion of reducing sugar relative to raw rice is 0.033 to 1.575% by weight, preferably 0.066 to 1.400% by weight, and more preferably 0.11 to 1.166% by weight.

[0014] In this invention, the sweetness levels of reducing sugars, with sugar set to 1, are as follows: palatinite 0.45, erythritol 0.85, lactitol 0.35, sorbitol 0.54, and maltitol 0.95.

[0015] In the present invention, the total amount of reduced starch hydrolysate and reducing sugar (total amount of sweetening components) is 33.0 to 50.0% by weight of the entire formulation, preferably 33.0 to 40.0% by weight.

[0016] In the rice flavor-improving and deterioration-preventing agent of the present invention, the ratio of reduced starch hydrolysate to reducing sugar is 5:45 to 45:5 by weight, preferably 1:4 to 4:1, and more preferably 1:2 to 2:1.

[0017] In this invention, to incorporate the rice flavor-improving and preservative agent into cooked rice, the preparation is added to raw rice before cooking in water (added water) or a seasoning liquid containing it, and then cooked, allowing the preparation to penetrate the rice sufficiently. The rice cooking method in this invention can be carried out using conventionally known general methods and is not particularly limited. As a pretreatment before cooking, it is sufficient to wash the raw rice and soak it in water; in the case of pre-washed rice, washing is not necessary. In the embodiments of the present invention, a rice cooker (JAI-H) manufactured by Tiger Corporation was used as the rice cooker pot, but the invention is not particularly limited to this. In normal rice cooking, the amount of water added is typically 120-160% by weight (standard amount) of water relative to the weight of the raw rice (including the weight absorbed during washing) after quickly washing and draining the rice before cooking. However, when cooking rice with the formulation of the present invention, 130-185% by weight, preferably 140-180% by weight, of the water added relative to the weight of the raw rice is used. Since people have preferences regarding the texture of rice (hardness, softness, etc.), in this test, a water addition amount of 150% by weight relative to the weight of the raw rice was used as the main standard amount.

[0018] In the present invention, the amount (X) of the rice flavor improving and deterioration prevention agent added is 1.0 to 3.5% by weight (0.6 to 2.1% by weight in the case of a powder formulation) relative to raw rice, preferably 1.2 to 3.0% by weight (0.7 to 1.8% by weight in the case of a powder formulation), and more preferably 1.5 to 3.0% by weight (0.9 to 1.8% by weight in the case of a powder formulation).

[0019] The additional water addition amount (Y) by weight during the cooking of rice in the present invention is the additional amount over the standard amount, and is 3 to 42% by weight based on the raw rice. Specifically, in relation to the addition amount of the flavor improving and quality deterioration preventing agent for cooked rice, when (X) is 1 to 3.5% by weight, the additional water addition amount (Y) by weight during the cooking of rice is in the range according to the formula: additional water addition amount (Y) by weight = (X) × 3 to (X) × 12 (water addition coefficient 3 to 12). Preferably, when (X) is 1.5 to 3.0% by weight, it is also in the range of (Y) = (X) × 3 to (X) × 12% by weight according to the same formula. In the case of a powder preparation, since there is no moisture in the preparation, the addition amount of the preparation is about 60% of that of the liquid preparation. Therefore, it is advisable to add the amount converted as a liquid preparation for the added water amount. The sweetening components of the flavor improving and quality deterioration preventing agent for cooked rice in the present invention are the hydrolyzate of reduced starch and reducing sugar contained in the preparation. The sweetness of the preparation is an index representing their sweetness, and is represented by the relative value when the sweetness intensity of 1% by mass of sucrose (20 °C) is taken as 1. The flavor improving and quality deterioration preventing agent for cooked rice of the present invention has a sweetness of 6 to 29, preferably 10 to 20, more preferably 11 to 19.

[0020] As the salt used in the present invention, in addition to natural products such as special grade salt, plain salt, white salt, roasted salt, refined salt, rock salt, and seaweed salt, there are also synthetic salts. However, if it is for food use, either a synthetic product or a natural product is acceptable. The blending ratio of the salt in the present invention is 0 to 17% by weight, preferably 5 to 14% by weight based on the whole preparation.

[0021] The flavor improving and quality deterioration preventing agent for cooked rice used in the present invention may be in powder form or paste form, but it is easier to use in liquid form in the manufacturing process of cooked rice. The method for preparing the liquid preparation used in the present invention is not particularly limited, and can be prepared by dissolving each weighed raw material in water. In actual production, it is desirable to produce it in a tank equipped with a stirrer. Also, in that case, some raw materials may be difficult to dissolve individually. It is considered that some components may aggregate when absorbing water to produce hardly soluble solids, and once these occur, they cannot be easily dissolved. In that case, it can be greatly improved by weighing the required amount of raw materials in advance, sieving, pulverizing if necessary, and uniformly mixing and formulating them. The water used in the manufacture of the present invention is not particularly restricted as long as it is purified water, but purified water with low mineral content is preferable. There are also no particular restrictions on the temperature of the purified water, but warm water is preferable because the raw materials dissolve more easily. Furthermore, the present invention can be prepared as a stable liquid formulation by preparing a concentrated solution that does not recrystallize at 0°C. It can also be diluted to adjust to the required concentration.

[0022] The effect of the rice flavor-improving and preservative agent of the present invention is further enhanced by adding organic acids or their salts. Examples of organic acids and inorganic acids and their salts that can be used include fumaric acid, monosodium fumarate, citric acid, trisodium citrate, sodium acetate, malic acid, sodium malate, tartaric acid, potassium bitartrate, sodium tartrate, succinic acid, monosodium succinate, disodium succinate, ferulic acid, phytic acid, adipic acid, lactic acid, sodium lactate, ascorbic acid, sodium ascorbate, gluconic acid (including glucono delta-lactone), sodium gluconate, sodium carbonate, sodium bicarbonate, and the like.

[0023] The rice flavor enhancer and spoilage inhibitor of the present invention and the food containing it may also be formulated with various additives depending on the purpose, such as amino acids like glycine, DL-alanine, and monosodium glutamate; seasonings like potassium chloride and salt; pH adjusters like sodium acetate; sweeteners; sugars; sugarcane extract; thickeners; acidulants; oils and fats; spices and their extracts; antibacterial agents such as ethanol, polylysine, protamine, nisin, hop extract, and lysozyme; preservatives; various vitamins; orthophosphates; metaphosphates; polyphosphates; pyrophosphates; nutritional fortifiers and antioxidants; enzymes (α-amylase, β-amylase, glucoamylase, α-glucosidase, etc.); and these may be added to the formulation or used in combination when the formulation is used.

[0024] The rice flavor enhancer and spoilage inhibitor of the present invention can be used in various processed rice products, such as plain cooked rice, rice seasoned during cooking (such as mixed rice dishes), rice seasoned after cooking (such as fried rice), and molded rice such as rice balls. Rice cooked using this method has a good flavor upon cooking, enhances its shelf life (bacteriostatic properties) at room temperature to refrigerated temperatures after cooking, and improves moisture retention. As a result, it maintains the fluffy texture of freshly cooked rice for a long period, minimizes and prevents deterioration of the rice during storage, and can be reheated in a microwave to reproduce the excellent texture, shelf life, and moisture retention that are close to that of freshly cooked rice. [Modes for carrying out the invention]

[0025] The present invention will be specifically described below with reference to examples. [Examples]

[0026] As the flavor-improving and spoilage-preventing agent for cooked rice of the present invention (which may be referred to as "formulation" in this specification), each of the components listed in Table 1 was mixed and dissolved to prepare formulations (a) to (n).

[0027] [Table 1] [Examples]

[0028] How to cook rice 1. Rice was cooked using a standard electric rice cooker without adding any additives during cooking (conventional method). 150g of uncooked rice was weighed and immediately rinsed with water. The amount of water added, including the water absorbed during rinsing, was adjusted to 225g (150% of the uncooked rice weight). After soaking for 20 minutes, the rice was cooked, and then steamed for another 20 minutes. 2. Add the preparation (f) from Table 1 and cook the rice using an electric rice cooker. The additional weight percentage of water added to raw rice was estimated based on the following formula. (X): Amount of formulation added (weight %) (Y): Amount of water added when cooking rice (by weight %) Formula: (Y) = (X) × 3 ~ (X) × 12 However, the upper limit for (Y) was set at 35% by weight. 150g of uncooked rice was weighed and immediately rinsed with water. Water was added to the uncooked rice so that the amount of water added, including the water absorbed during rinsing, was [standard amount + (Y)]% of the weight of the uncooked rice. Rice flavor enhancer and spoilage inhibitor (f) was added to the added water and stirred well. After soaking in water for 20 minutes, the rice was cooked in an electric rice cooker and then steamed for another 20 minutes. White rice was cooked using the method described above, and the cooked rice was weighed. The results are shown in Table 2.

[0029] [Table 2] *The weight of cooked rice is the weight (g) after steaming for 20 minutes after cooking, and the yield is the weight percentage when the weight of additive-free cooked rice (150% of the standard amount) is set to 100%.

[0030] 3. Observation of the texture of cooked rice and its state of deterioration during storage. A sensory evaluation was conducted by 10 experienced panelists, comparing freshly cooked rice and rice stored at 10°C for 24 and 48 hours before and after microwave heating. The results are shown in Table 3.

[0031] [Table 3] *The 10°C storage test was discontinued for samples that were too soft, as they could not be deemed to have any commercial value. Criteria for evaluating the state of aging A: Close to freshly cooked, good. B: Shows almost no signs of aging, in good condition. C: Slight aging, good condition D: Somewhat aged E: Aging is progressing F: Extremely advanced aging [Examples]

[0032] Based on the rice cooking method of Example 2, the yield of cooked rice was measured for rice cooked with formulations (a) and (j) listed in Table 1 of Example 1 added, and for cooked rice cooked without any additives or with only acetic acid added. The results are shown in Table 4.

[0033] [Table 4] The results of the sensory evaluation by 10 experienced panelists are shown in Table 5.

[0034] [Table 5] *The 10°C storage test was discontinued for samples that were too soft, as they could not be deemed to have any commercial value.

[0035] Preservation test Method: After steaming, cooked rice was cooled to room temperature (15°C), aseptically divided into 10g portions, inoculated with 0.1ml of Bacillus cereus solution (300 CFU / ml), and stored at 15°C. Table 6 shows the elapsed time and total bacterial count.

[0036] [Table 6] [Examples]

[0037] White rice was cooked using the formulations shown in Table 1, following the cooking method of Example 2, and the yield (Table 7), the state of the cooked rice, and the state of aging after storage (Table 8) were compared by sensory testing.

[0038] [Table 7] Results of sensory evaluation (by 10 experienced panelists)

[0039] [Table 8] *The 10°C storage test was discontinued for samples that were too soft, as they could not be deemed to have any commercial value. Assessment of the state of aging A: Close to the state after cooking, good. B: Shows almost no signs of aging, in good condition. C: Slight aging, good condition D: Somewhat aged E: Aging is progressing F: Extremely advanced aging [Examples]

[0040] White rice was cooked using the formulations shown in Table 1, following the cooking method of Example 2, and the yield (Table 9), the state of the cooked rice, and the state of aging after storage (Table 10) were compared by sensory testing.

[0041] [Table 9] Sensory evaluation (by 10 experienced panelists)

[0042] [Table 10] Assessment of the state of aging A: Close to the state after cooking, good. B: Shows almost no signs of aging, in good condition. C: Slight aging, good condition D: Somewhat aged E: Aging is progressing F: Extremely advanced aging

[0043] Preservation test Method: Cooked rice, after steaming and cooling to room temperature, was aseptically divided into 10g portions. Each portion was inoculated with 0.1ml of Bacillus cereus solution (300 CFU / ml) and stored at 25°C. The relationship between storage time and total viable cell count is shown in Table 11.

[0044] [Table 11] [Examples]

[0045] White rice was cooked using the formulations shown in Table 1, following the cooking method of Example 2. The yield (Table 12), the state of the cooked rice, and the state of aging after storage (Table 13) were compared by sensory testing.

[0046] [Table 12] Formulation (n) could not be formulated because the solute was insoluble, but each component was added to the added water separately for sweetness comparison and testing was conducted. Sensory evaluation (by 10 experienced panelists) results

[0047] [Table 13] Assessment of the state of aging A: Close to the state after cooking, good. B: Shows almost no signs of aging, in good condition. C: Slight aging, good condition D: Somewhat aged E: Aging is progressing F: Extremely advanced aging

[0048] Preservation test Method: After steaming and cooling to room temperature, cooked rice was aseptically divided into 10g portions. 0.1ml of Bacillus cereus solution (300 CFU / ml) was inoculated into each portion, and the total number of viable bacteria was measured after incubating at 10°C for 24 to 96 hours. The results are shown in Table 14.

[0049] [Table 14] [Examples]

[0050] Following the cooking method of Example 2, an α-amylase preparation (Spitase R, manufactured by Nagase ChemteX Corporation) was added at a rate of 0.1% relative to the raw rice in the step before the start of cooking. White rice was then cooked using the preparation (f) shown in Table 1, and the yield (Table 15), the state of the cooked rice, and the state of aging after storage (Table 16) were compared by sensory testing. In this experiment, the standard amount of cooking water was set to 130% by weight of the raw rice.

[0051] [Table 15] *0.1% Spitase R was added to all samples except 7-2. Results of sensory evaluation (by 10 experienced panelists)

[0052] [Table 16] Assessment of the state of aging A: Close to the state after cooking, good. B: Shows almost no signs of aging, in good condition. C: Slight aging, good condition D: Somewhat aged E: Aging is progressing F: Extremely advanced aging [Industrial applicability]

[0053] The cooked rice obtained by the method of the present invention is substantially free of acetic acid odor and sourness, has a high yield, good flavor, and excellent shelf life at room temperature. Moreover, the flavor and texture when reheated in a microwave or steamer after being stored at room temperature or low temperature is comparable to that of freshly cooked rice. Therefore, this method can be implemented in supermarkets, convenience stores, restaurants, and eateries that manufacture and sell rice-based foods, such as packaged white rice, red bean rice, mixed rice, and rice balls.

Claims

1. A method for producing cooked rice, comprising adding 1.0 to 3.5% by weight of a rice flavor enhancer and preservative to 130 to 185% by weight of cooking water relative to the raw rice, and cooking the rice. The additive contains 1.0 to 18.2% by weight of acetic acid, 6.6 to 40.0% by weight of reduced starch hydrolysate with a sweetness of 0.1 to 0.3, 6.6 to 40.0% by weight of palatinite (registered trademark), and 0 to 17.0% by weight of salt, with a weight ratio of 4 / 1 to 1 / 4 for the reduced starch hydrolysate and palatinite (registered trademark), and a total weight of 33.0 to 50.0% by weight of the combined additive.

2. A method for producing cooked rice according to claim 1, wherein the rice flavor improving and deterioration prevention agent contains 1.4 to 15.6% by weight of acetic acid, 6.6 to 40.0% by weight of reduced starch hydrolysate with a sweetness of 0.1 to 0.3, 6.6 to 40.0% by weight of palatinite (registered trademark), and 5 to 14.0% by weight of salt, the weight ratio of the reduced starch hydrolysate to palatinite (registered trademark) is 4 / 1 to 1 / 4, and the total weight of both is 33.0 to 50.0% by weight.

3. A flavor-improving and spoilage-preventing agent for cooked rice, containing 1.0 to 18.2% by weight of acetic acid, 6.6 to 40.0% by weight of reduced starch hydrolysate with a sweetness of 0.1 to 0.3, 6.6 to 40.0% by weight of palatinite (registered trademark), and 0 to 17% by weight of salt, wherein the weight ratio of the reduced starch hydrolysate to palatinite (registered trademark) is 4 / 1 to 1 / 4, and the total weight of both is 33.0 to 50.0% by weight.

4. A flavor-improving and spoilage-preventing agent for cooked rice according to claim 3, comprising 1.4 to 15.6% by weight of acetic acid, 6.6 to 40.0% by weight of reduced starch hydrolysate with a sweetness of 0.1 to 0.3, 6.6 to 40.0% by weight of palatinite (registered trademark), and 5 to 14% by weight of salt, wherein the weight ratio of the reduced starch hydrolysate to palatinite (registered trademark) is 4 / 1 to 1 / 4, and the total weight of both is 33.0 to 50.0% by weight.

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