JP7565718B2 - Hardening inhibitor for cooked rice-containing foods, cooked rice-containing foods, and method for inhibiting hardening of cooked rice-containing foods - Google Patents

Description

The present invention relates to a hardening inhibitor for cooked rice-containing foods, cooked rice-containing foods, and a method for inhibiting hardening of cooked rice-containing foods.

There are many cooked rice products distributed chilled or frozen, but cooked rice hardens over time after cooking, and hardening accelerates significantly at low temperatures, so the texture deteriorates over time or when stored at low temperatures. If the texture deteriorates, it may become less palatable. For this reason, various methods are being studied to prevent deterioration in the texture of cooked rice during storage.

For example, methods proposed to improve the texture of stored cooked rice include adding trehalose (Patent Document 1) and adding a yeast-treated product and a thickening stabilizer to rice before cooking (Patent Document 2).

Patent No. 3037044 Patent No. 6704274

However, it is desirable to prevent the hardening of cooked rice and further improve the texture.

The present invention has been made in consideration of the above-mentioned circumstances, and aims to provide a hardening inhibitor for cooked rice-containing foods that can inhibit the hardening of cooked rice-containing foods, a cooked rice-containing food, and a method for inhibiting the hardening of cooked rice-containing foods.

The inventors discovered that the above problems can be solved by using a hardening inhibitor containing maltobionic acid or a maltobionate salt, and thus completed the present invention. More specifically, the present invention provides the following:

(1) A hardening inhibitor for cooked rice-containing foods, comprising at least one component selected from maltobionic acid and maltobionate salts.

(2) The hardening inhibitor for cooked rice-containing foods described in (1), wherein the maltobionate is calcium maltobionate.

(3) The hardening inhibitor for cooked rice-containing foods according to (1) or (2), wherein the cooked rice-containing food is cooked rice.

(4) A cooked rice-containing food product comprising a hardening inhibitor for cooked rice-containing foods described in any one of (1) to (3).

(5) A method for inhibiting hardening of cooked rice-containing foods, comprising the step of blending a hardening inhibitor for cooked rice-containing foods described in any one of (1) to (3) into the cooked rice-containing food.

The present invention provides a hardening inhibitor for cooked rice-containing foods that can inhibit hardening of cooked rice-containing foods, cooked rice-containing foods, and a method for inhibiting hardening of cooked rice-containing foods.

Specific embodiments of the present invention are described in detail below, but the present invention is not limited to the following embodiments and can be modified as appropriate within the scope of the object of the present invention. Note that where explanations overlap, they may be omitted as appropriate, but this does not limit the gist of the invention.

<Hardening inhibitor for foods containing cooked rice>
The hardening inhibitor for cooked rice-containing foods of the present invention (hereinafter also referred to as "hardening inhibitor of the present invention") contains at least one component selected from maltobionic acid and maltobionate salts.

Rice-containing foods in which the hardening inhibitor of the present invention inhibits hardening include, but are not limited to, cooked rice obtained by cooking rice such as polished rice, brown rice, or glutinous rice, as well as red rice, steamed red steamed rice, seasoned rice, pilaf, dry curry, vinegared rice, and other processed cooked rice such as rice balls and sushi rice, or frozen cooked rice obtained by freezing these.

(Maltobionic acid and its salts)
The curing inhibitor of the present invention contains at least one component selected from maltobionic acid and maltobionate salts. These may be used alone or in combination of two or more kinds.
In this way, by including maltobionic acid or a maltobionate, hardening of cooked rice-containing foods can be suppressed.

Starch, the main component of raw rice, has a hard crystalline structure formed by hydrogen bonds. When cooked, the hydrogen bonds of the starch are broken and the rice absorbs water molecules, softening it; this is called starch gelatinization. If cooked rice is left to sit or stored at low temperatures, the water molecules separate from the starch, causing it to gradually harden; this is called starch aging. When cooked rice-containing foods harden due to starch aging (hardening), the texture of the cooked rice-containing foods is significantly impaired.
Maltobionic acid and maltobionate have one carboxyl group and multiple hydroxyl groups, and therefore have a very high affinity with water. As a result, maltobionic acid and maltobionate can suppress water release from gelatinized starch, i.e., maltobionic acid and maltobionate have high water retention. For this reason, it is presumed that the inclusion of maltobionic acid and maltobionate can suppress starch retrogradation (hardening).
In this way, the hardening inhibitor of the present invention can suppress the hardening of starch, and therefore has the effect of suppressing the hardening of cooked rice-containing foods over time and the hardening of cooked rice-containing foods due to low-temperature storage. Therefore, even if time passes after cooking or the food is stored at low temperature, the food can maintain a favorable texture (softness). In addition, since it suppresses water release from gelatinized starch, it also has the effect of suppressing dryness of cooked rice-containing foods due to storage.

For example, when the cooked rice-containing food is cooked rice obtained by cooking polished rice, the hardening inhibitor of the present invention can be used to reduce the hardness of the cooked rice to 120% or less after 24 hours of refrigerated storage at 4°C or frozen storage at -20°C, assuming that the hardness is 100% when the rice is cooked, steamed for 1 hour, and cooled at room temperature for 1 hour. The hardness of cooked rice is determined by the method shown in the examples.

In addition, while conventionally known aging inhibitors may impart a sweet taste or other flavor, the maltobionic acid and maltobionate salts contained in the hardening inhibitor of the present invention as hardening inhibitor components (aging inhibitors) have a weak taste intensity themselves, so the hardening inhibitor of the present invention can inhibit the hardening of cooked rice-containing foods without imparting or almost without imparting any unnecessary flavors such as sweetness.

Maltobionate salts include mineral salts of maltobionic acid. There are no particular limitations on the minerals as long as they can be incorporated into foods. Specific examples of maltobionate salts include calcium maltobionate, sodium maltobionate, potassium maltobionate, etc.

Maltobionic acid and maltobionate salts may be in the form of maltooligosaccharide oxide, starch syrup oxide, powdered syrup oxide or dextrin oxide.

Maltobionic acid and maltobionate salts may be in the form of a liquid (such as a syrup) or a powder.

(Method of producing maltobionic acid and its salts)
Maltobionic acid and maltobionate salts can be produced according to conventional methods.
Examples of methods for producing maltobionic acid include (1) a method of oxidizing starch hydrolysates by chemical oxidation reaction, and (2) a method of reacting starch hydrolysates with a microorganism or oxidase capable of oxidizing oligosaccharides.
Among the above, the method (2) includes, for example, a method in which an oxidase is extracted from a microorganism having an ability to oxidize oligosaccharides, such as Acremonium chrysogenum, and the enzyme is allowed to act.

A salt of maltobionic acid and a divalent mineral can be produced, for example, by adding a mineral (salt) to maltobionic acid.
For example, when producing calcium maltobionate, a calcium source such as calcium carbonate can be added to a maltobionic acid solution in a molar ratio of 2:1, and dissolved to prepare calcium maltobionate. The calcium source used in this case is not particularly limited as long as it is edible calcium, and may be, for example, any of natural materials (eggshell powder, coral powder, bone powder, shell powder, etc.) and chemically synthesized products (calcium carbonate, calcium chloride, etc.).

(Other ingredients)
The cure inhibitor of the present invention may contain any optional component within the range that does not impair the effects of the present invention. Examples of such optional ingredients include water, flavorings, thickeners, sweeteners (sugar, isomerized sugar, glucose, fructose, fructose-glucose syrup, glucose-fructose syrup, honey, starch syrup, powdered syrup, maltodextrin, sorbitol, maltitol, reduced starch syrup, maltose, trehalose, brown sugar, etc.), dietary fiber, proteins (milk, soybeans, beef extract, chicken extract, pork extract, fish extract, gelatin, etc.), acidulants (organic acids such as citric acid, acetic acid, lactic acid, malic acid, and tartaric acid), minerals (calcium, magnesium, iron, potassium, zinc, copper, etc.), amino acids (arginine, valine, leucine, isoleucine, etc.), spices (garlic, ginger, sesame, chili pepper, wasabi, Japanese pepper, Japanese ginger, etc.), emulsifiers, enzymes, functional ingredients, preservatives, stabilizers, antioxidants, vitamins, etc. The amounts of these components added can be appropriately adjusted depending on the effect to be obtained.

The hardening inhibitor of the present invention may or may not contain a conventionally known physical property improver for cooked rice. Conventional physical property improvers for cooked rice include carbohydrates (trehalose, thickening polysaccharides), etc.

The hardening inhibitor of the present invention may or may not contain components used in conventionally known methods for producing cooked rice, etc. Examples of such components include pH adjusters, organic acids, etc.

<Foods containing cooked rice, including hardening inhibitors for foods containing cooked rice>
The cooked rice-containing food of the present invention contains the hardening inhibitor for cooked rice-containing food of the present invention described above. Therefore, the cooked rice-containing food of the present invention is inhibited from hardening of starch, and thus hardening over time and hardening due to low-temperature storage are inhibited. Therefore, the cooked rice-containing food of the present invention can maintain a preferable texture (softness) even after time has passed or after low-temperature storage after cooking. Dryness due to storage is also inhibited. In addition, the cooked rice-containing food can be made to have no or almost no extra taste such as sweetness due to the hardening inhibitor.

The amount of the hardening inhibitor of the present invention contained in the cooked rice-containing food is not particularly limited, and is selected appropriately depending on the type of cooked rice-containing food, the hardness to be achieved, etc.

For example, the hardening inhibitor of the present invention is blended so that the total of maltobionic acid and maltobionate salts is preferably 0.1 parts by weight or more, more preferably 0.2 parts by weight or more, per 100 parts by weight of raw rice. Also, the hardening inhibitor of the present invention is blended so that the total of maltobionic acid and maltobionate salts is preferably 10 parts by weight or less, more preferably 5 parts by weight or less, per 100 parts by weight of raw rice. When the amount is 0.1 parts by weight or more, it is easy to impart preferred physical properties such as hardness to cooked rice-containing foods, and when the amount is 10 parts by weight or less, the physical properties such as hardness imparted to cooked rice-containing foods are appropriate.

The content of maltobionic acid or maltobionate in the cooked rice-containing food of the present invention can be calculated by the HPAED-PAD method (pulsed amperometric detector, CarboPac PA1 column).
The measurement conditions for the HPAED-PAD method are as follows.
Elution: 35°C, 1.0 ml/min
Sodium hydroxide concentration: 100 mM
Sodium acetate concentration: 0 min-0 mM, 5 min-0 mM, 55 min-40 mM

When producing the cooked rice-containing food of the present invention, the timing of blending the hardening inhibitor of the present invention with the cooked rice-containing food is not particularly limited and can be appropriately selected depending on the type of cooked rice-containing food, etc.
For example, the hardening inhibitor of the present invention may be mixed before or during cooking rice, or after cooking rice.

The cooked rice-containing food produced using the hardening inhibitor of the present invention may be sterilized or packed into containers as necessary. There are no particular limitations on the method or order of sterilization and packing.

When the cooked rice-containing food produced using the hardening inhibitor of the present invention is packed into a container, examples of the container include resin products such as polyethylene terephthalate (PET) (retort pouch containers, plastic bottles, etc.), metal products such as steel and aluminum (cans, etc.), and paper cartons.

<Method for preventing hardening of foods containing cooked rice>
The method of the present invention for inhibiting hardening of cooked rice-containing foods (hereinafter also referred to as the "hardening inhibition method of the present invention") comprises the step of blending the above-mentioned hardening inhibitor for cooked rice-containing foods of the present invention into a cooked rice-containing food.

In the hardening inhibition method of the present invention, the timing and amount of the hardening inhibitor of the present invention added to the cooked rice-containing food can be appropriately selected depending on the type of food and the physical properties such as hardness to be achieved, and are not particularly limited. For example, the conditions listed in the above section <Cooked rice-containing food containing a hardening inhibitor for cooked rice-containing food> can be used.

The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples.

<Test 1: Rice>
Raw rice was cooked using the following ingredients and the change in hardness during storage was evaluated.

(material)
Maltobionic acid syrup (70% by mass of maltobionic acid, 30% by mass of water): manufactured by Sanei Saccharomyces Co., Ltd. Calcium maltobionic acid (powder): manufactured by Sanei Saccharomyces Co., Ltd. Trehalose (powder): manufactured by Hayashibara Co., Ltd.

(Preparation of cooked rice)
Commercially available raw rice (Akitakomachi rice produced in Akita Prefecture, polished rice) was used to prepare cooked rice in the following manner.
(1) 150 g of raw rice was washed and transferred to a rice cooker, and the mass of water shown in Table 1 was added thereto until the total amount was 368 g.
(2) Maltobionic acid syrup, calcium maltobionic acid, and trehalose were added in the amounts shown in Table 1, mixed lightly, and then cooked in a rice cooker.
(3) After cooking, stir the rice lightly with a rice spoon and leave it to steam for one hour with the heat turned off.
(4) 50 g portions were wrapped in plastic wrap and allowed to cool at room temperature for 1 hour, and then stored in a refrigerator at 4° C. or frozen at −20° C. for 24 hours.

(Hardness measurement)
The hardness of the cooked rice was measured by the following method immediately after cooling at room temperature for 1 hour (same day), after refrigerated storage (refrigerated for 24 hours), and after frozen storage (frozen for 24 hours). The measurement was repeated 10 times and the average value was calculated. The results are shown in the "Load" section of Table 1.
The hardness was measured using a rheometer (manufactured by Yamaden Co., Ltd.), and the maximum load when three cooked rice grains were compressed to 50% of the sample height with a Φ30 mm cylindrical plunger at a compression speed of 1 mm/s was regarded as the hardness of each cooked rice. Those in which the increase in hardness was suppressed compared to the day of cooking were judged to have a hardening inhibition effect. The increase rate of hardness indicates the hardness after storage when the hardness on the day is taken as 100%.

As shown in Table 1, the hardness of cooked rice increases when stored in a refrigerator or freezer, but it was confirmed that this increase can be suppressed by adding maltobionic acid or calcium maltobionate.
<Test 2: Vinegared rice>
Vinegared rice was prepared using the following ingredients and the change in hardness during storage was evaluated.

(material)
Maltobionic acid syrup (70% by mass of maltobionic acid, 30% by mass of water): manufactured by Sanei Sugar Co., Ltd. Vinegar: manufactured by Mitsukan Sugar: manufactured by Nisshin Sugar Co., Ltd. Salt: manufactured by Salt Business Center

(Preparation of vinegared rice)
Vinegared rice was prepared using commercially available raw rice (Akita Komachi, polished rice produced in Akita Prefecture) in the following manner.
(1) 150 g of raw rice was washed and transferred to a rice cooker, and water of the mass shown in Table 2 was added to make the total amount 368 g.
(2) I cooked rice in a rice cooker.
(3) Maltobionic acid syrup, vinegar, sugar, salt, and water in the amounts shown in Table 2 were mixed and heated until boiling.
(4) The mixture obtained in (3) was mixed with cooked rice immediately after the completion of cooking and mixed thoroughly.
(5) 50 g each was wrapped in plastic wrap and left to cool at room temperature for 1 hour, and then refrigerated at 4° C. for 24 hours.

In the same manner as above (measurement of hardness), the hardness of the vinegared rice was measured immediately after cooling at room temperature for 1 hour (on the same day) and after refrigerated storage (refrigerated for 24 hours).

As shown in Table 2, it was confirmed that maltobionic acid can suppress hardening of cooked rice even when mixed with cooked rice, such as vinegared rice.

Claims (5)

A hardening inhibitor for cooked rice-containing foods , comprising at least one component selected from maltobionic acid and maltobionate salts, and blended so that the total amount of said components is 0.1 parts by mass or more per 100 parts by mass of raw rice . The hardening inhibitor for cooked rice-containing foods according to claim 1, wherein the maltobionate is calcium maltobionate. The hardening inhibitor for cooked rice-containing foods according to claim 1 or 2, wherein the cooked rice-containing food is cooked rice. A cooked rice-containing food comprising the hardening inhibitor for cooked rice-containing foods according to any one of claims 1 to 3, wherein the total amount of the components is 0.1 parts by mass or more per 100 parts by mass of raw rice . A method for inhibiting hardening of cooked rice-containing foods , comprising the step of blending the hardening inhibitor for cooked rice-containing foods according to any one of claims 1 to 3 with the cooked rice-containing food so that the total amount of the components is 0.1 parts by mass or more per 100 parts by mass of raw rice .