JP7489861B2 - Soup for frozen food, its manufacturing method, and frozen food using said soup for frozen food - Google Patents

Description

The present invention relates to soup for frozen foods, a method for producing the same, and frozen foods using the soup for frozen foods.

In recent years, many frozen foods that can be easily cooked in a microwave oven have been released onto the market, and examples of frozen foods that use soup or sauce include frozen udon, frozen ramen, and frozen pasta. Of these, frozen pasta mainly contains sauce directly in the noodles, as only a small amount of sauce is added and there are few problems if the color of the sauce transfers to the noodles, and it can be eaten by cooking only in a microwave. In contrast, frozen udon and frozen ramen mainly contain concentrated soup separately, and the general method is to cook the noodles and ingredients in a microwave oven, and then add the noodles and ingredients to the soup prepared in advance by dissolving the soup separately in hot water, or to cook the noodles and ingredients in a pot and then add the soup separately provided.

In recent years, attempts have been made to reduce the amount of packaging used for soup separately, not only to simplify cooking methods but also from an environmental perspective, and to fill the soup directly instead. When cooking in a pot, frozen foods such as frozen udon and ramen can be frozen with the noodles in straight soup rather than concentrated soup, but when cooking in a microwave, freezing the noodles in straight soup can take too long to thaw. In addition, when concentrated soup is directly filled into the noodles, there is the problem that the color of the soup can transfer to the noodles, the main ingredient, during production, storage, and cooking in a microwave oven, etc.

As a method to solve these problems, the method disclosed in Patent Document 1 is described. Patent Document 1 describes a frozen food in which the seasoning liquid is placed on top of the staple food in a container, the viscosity of the seasoning liquid at 70°C being 1000-8000 cP measured with a C-type viscometer, and the seasoning liquid and the staple food are frozen in contact with each other only partially rather than entirely, and it is described that this reduces the transfer of moisture from the seasoning liquid to the staple food (noodles or rice), saves the effort of eating, and reduces packaging costs.

Also, the techniques of forming a two-layer soup are known from Patent Documents 2 to 4. Patent Document 2 describes a frozen seasoning liquid block and a frozen food with seasoning liquid suitable for thawing and cooking in a microwave oven or the like, and a method for producing the same, which is a frozen food with seasoning liquid comprising a frozen seasoning liquid block having a first layer containing a frozen first component and a second layer containing a frozen second component stacked on top of a frozen main ingredient block, the frozen seasoning liquid block being placed with the second layer underneath, the first component having a lower fluidity at 60°C than the second component, the frozen seasoning liquid block being placed such that the entire outer periphery of the frozen seasoning liquid block is contained within the outer periphery of the main ingredient block in a plan view, the bottom of the frozen seasoning liquid block being embedded in the main ingredient block, and the upper part of the frozen seasoning liquid block including at least a part of the second layer protruding from the peripheral upper surface of the main ingredient block. However, the two layers are laminated, and the structure of the present invention is not one in which the inner soup layer is enclosed by the outer soup layer, and the second layer, which has high fluidity, needs to come into contact with the main ingredient mass, so the soup cannot be directly poured into the main ingredient and must be frozen beforehand before being poured.

Patent Document 3 describes packaged frozen noodles in which moisture transfer from the sauce to the boiled noodles is suppressed even when the sauce and boiled noodles are packaged together, and which are characterized in that the frozen sauce layer with the highest Brix degree of the frozen sauce, which is composed of multiple layers of frozen sauce layers with different Brix degrees, with the frozen sauce layer with the highest Brix degree as the outer layer, is in direct contact with the frozen noodle block surface obtained by freezing the frozen sauce separately. However, soup with a high Brix is easily dissolved during transportation or frozen storage due to the freezing point effect, and if it contains colorants, color transfer to the noodles is likely to occur. Furthermore, the technology described in Patent Document 3 requires the frozen noodles and sauce to be frozen separately, and direct filling is not possible, so the frozen noodle block must be placed on top of the sauce.

Patent Document 4 describes a gelled sauce that has high storage stability and can be stored in a solid state at room temperature, the gelled sauce comprising a first gelled sauce and a second sauce coated thereon, the first sauce having a pH of 7.0 or less and an Aw of more than 0.80 and not more than 0.90 and higher than the Aw of the second sauce, and the second sauce having a pH of 3.5 to 7.0 and an Aw of 0.80 or more and less than 0.86. However, the first sauce needs to be gelled at room temperature, and it dissolves when cooked with heat to become a low-viscosity sol, so there is a possibility that color transfer to the noodles or moisture transfer to the noodles during cooking, resulting in an uneven texture.

Patent No. 4654772 Patent No. 4197671 Patent No. 4091535 JP 2019-205357 A

The present invention aims to provide a soup for frozen foods that can be directly packed into the main ingredient of a frozen food even if it is a concentrated soup, reducing packaging materials and allowing for simple cooking, and a frozen food containing said soup for frozen foods. In addition, the present invention aims to provide a soup for frozen foods that causes little color transfer to the food during freezing or cooking in a microwave oven, even when a colored concentrated soup such as soy sauce ramen is directly packed into the main ingredient of the frozen food, and a frozen food containing said soup for frozen foods.

The inventors have investigated a method for filling noodles, the main ingredient, with concentrated soup directly in frozen foods with colored soup such as soy sauce ramen, to reduce packaging materials and simplify cooking. However, simply filling noodles directly with regular concentrated soup results in the concentrated soup pooling at the bottom of the freezer container used to freeze the noodles, and the color of the soup transfers to the noodle strings during freezing or cooking in a microwave, making for a poor appearance. In addition, the concentrated soup burns when cooking in a microwave. As a result of extensive research, the inventors have discovered a soup for frozen foods that can be filled directly into the main ingredient, even if it is concentrated soup, and that prevents color transfer to the main ingredient during freezing or cooking, which led to the present invention.

That is, it is a soup for frozen foods that has a two-layer structure, in which an inner layer soup is enclosed by an outer layer soup, and the viscosity of the outer layer soup when filled is 270 Pa·s or more, and the viscosity of the outer layer soup at 60°C is 250 Pa·s or more.

It is also preferable that the outer layer soup contains at least one of gelatin, starch, or thickening polysaccharides.

In addition, the outer layer soup contains at least starch, and the type of starch preferably contains at least one of phosphate cross-linked starch, hydroxypropyl phosphate cross-linked starch, or acetylated phosphate cross-linked starch.

In addition, it is preferable that the weight of the outer layer soup in the frozen food soup is at least twice the weight of the inner layer soup.

It is also preferable that the inner soup layer contains more pigment components that will transfer color to the main ingredient than the outer soup layer.

Frozen food soup is preferably filled directly into the frozen food.

The soup for frozen foods having a two-layer structure according to the present invention is preferably used in frozen foods, and more preferably in frozen noodles.

When the frozen food soup having a double structure according to the present invention is used in a frozen food, it is preferable that the frozen food contains a heat-resistant amylase.

In addition, in the method for producing the frozen soup food having a double structure according to the present invention, it is preferable that the viscosity of the outer layer soup when filled is 270 Pa·s or more, and the viscosity at 60°C is 250 Pa·s or more, and that the soup is produced using a two-liquid filling nozzle.

The present invention makes it possible to provide a soup for frozen foods that allows concentrated soup to be directly packed into food, reducing packaging materials and enabling simple cooking, and a frozen food that contains the soup for frozen foods. Furthermore, even when colored concentrated soup such as soy sauce ramen is directly packed into frozen foods, it is possible to provide a soup for frozen foods and a frozen food that contains the soup for frozen foods that causes little transfer of soup color to the food during storage in the freezer or cooking in a microwave oven, etc.

FIG. 2 is a top view of soup A for frozen foods according to an embodiment of the present invention. This is a cross-sectional view of soup A for frozen foods according to an embodiment of the present invention taken along line α-α'. FIG. 2 is a top view of frozen food B according to an embodiment of the present invention. This is a β-β' cross-sectional view of frozen food B according to an embodiment of the present invention. 1 is a top view of soup A' for frozen food and frozen food B', which are modified examples of the frozen food according to an embodiment of the present invention. FIG. 7 is a cross-sectional view of frozen food soup A' and frozen food B', which are modified examples of frozen foods according to an embodiment of the present invention, taken along line γ-γ'. FIG. FIG. 2 is a top view of frozen food B″, which is a modified example of the frozen food according to the embodiment of the present invention. FIG. 2 is a bottom view of frozen food B″, which is a modified example of the frozen food according to the embodiment of the present invention. FIG. 2 is a cross-sectional view taken along line Δ-Δ′ of frozen food B″, which is a modified example of the frozen food according to the embodiment of the present invention. FIG. 2 is an explanatory diagram showing an example of preparation of frozen food B', which is a modified example of the frozen food according to the embodiment of the present invention. FIG. 1 is an explanatory diagram showing an example of preparation of frozen food B″, which is a modified example of the frozen food according to the embodiment of the present invention. These are a top view photograph of a frozen food sample of Example 3, a bottom view photograph after the abuse treatment, a top view photograph of the abuse-treated sample after cooking in a microwave, and a photograph of the noodles of the abuse-treated sample after being heated to boiling water. This is a photograph of the top surface of a frozen food sample of Comparative Example 1, a photograph of the bottom surface after abuse treatment, and a photograph of the noodles of the abuse-treated sample after being heated to boiling water. These are a top view photograph of a frozen food sample of Comparative Example 3, a bottom view photograph after the abuse treatment, a top view photograph of the abuse-treated sample after cooking in a microwave, and a photograph of the noodles of the abuse-treated sample after being heated to boiling water.

1 Inner layer soup 2 Outer layer soup 3 Main food 4 Ice layer containing heat-resistant amylase 5 Freezing container 6 Inner layer soup nozzle 7 Outer layer soup nozzle 8 Two-liquid filling nozzle 9 Aqueous solution of heat-resistant amylase A Soup for frozen food B Frozen food

The present invention will be described in detail below. However, the present invention is not limited to the following description.

(1) Soup for frozen foods The soup for frozen foods according to the present invention has a two-layer structure having an inner layer soup 1 and an outer layer soup 2 that encompasses it, such as soup A for frozen foods shown in Figures 1 and 2 and soup A' for frozen foods shown in Figures 7 and 9.

The outer layer soup 2 of the present invention preferably has a viscosity of 270 Pa·s or more when filled. If the viscosity is less than 270 Pa·s, not only is it difficult to contain the inner layer soup 1 when the inner layer soup 1 has a low viscosity, but when filled directly onto the main ingredient 3, it is difficult for the frozen food soup to remain on top of the main ingredient 3. Conversely, if the viscosity is too high, it becomes difficult to fill from the nozzle. The viscosity is preferably 550 to 1610 Pa·s. The viscosity is measured using a B-type viscometer at each temperature when filling. The rotor and rotation speed can be measured using rotor number 4 at a rotation speed of 0.3 rpm.

The outer layer soup 2 of the present invention preferably has a viscosity of 250 Pa·s or more at 60°C. If it is less than 250 Pa·s, the molten outer layer soup 2 may fall through gaps in the main food 3 during cooking in a microwave oven or the like, causing the inner layer soup 1 to come into contact with the main food 3, or may boil and stain the main food 3. Furthermore, the inner layer soup 1 may burn as it falls. Conversely, if the viscosity is too high, the outer layer soup 2 may be difficult to dissolve in hot water or difficult to mix homogeneously. A viscosity of 520 to 1140 Pa·s is preferable. The viscosity is measured by measuring the outer layer 2 soup adjusted to 60°C with a B-type viscometer. The rotor and rotation speed may be measured with rotor number 4 at a rotation speed of 0.3 rpm.

The viscosity of the outer layer soup 2 according to the present invention is preferably adjusted by at least one of gelatin, starch, and thickening polysaccharides. In order to directly fill the frozen food soup according to the present invention, it is necessary to have a high viscosity, and it is preferable that the soup maintains its viscosity even after heating, such as in a microwave oven, remains on top of the main ingredient 3, and is soluble in hot water if necessary. Therefore, it is preferable to adjust the viscosity based on starch, which is easy to maintain its viscosity even at high temperatures and is easily soluble in hot water.

When starch is used to adjust the viscosity of the outer layer soup 2 according to the present invention, the type of starch is not particularly limited, and examples include potato starch, tapioca starch, corn starch, waxy corn starch, sago starch, mung bean starch, wheat starch, rice starch, and processed starches obtained by subjecting these to etherification, esterification, phosphorylation, oxidation, and the like. One or more of these starches can be selected and used. The starch used in the present invention is preferably a starch that is resistant to freezing, and phosphate cross-linked starch, hydroxypropylated phosphate cross-linked starch, and acetylated phosphate cross-linked starch are preferred. The amount of starch added depends on the viscosity of the outer layer soup, but is preferably 5 to 15% by weight. If it is less than 5% by weight, sufficient viscosity cannot be expressed, and if it is more than 15% by weight, the viscosity becomes too high, making it difficult to fill the soup with a nozzle.

The viscosity of the outer layer soup 2 of the present invention can also be adjusted using gelatin or thickening polysaccharides. By using gelatin or thickening polysaccharides in addition to starch, it is possible to improve the filling suitability of the soup for frozen foods, and also to adjust the viscosity of the soup after cooking, which cannot be achieved with starch alone. Examples of thickening polysaccharides include guar gum, xanthan gum, tara gum, tamarind seed gum, and succinoglycan. As for gelatin, any type of gelatin can be used, such as sheet gelatin, powdered gelatin, or granular gelatin. In addition, any type of gelatin derived from pork, beef, or fish can also be used. The amount of thickener added depends on the desired viscosity of the soup for frozen noodles and the type of thickener, but it can be added to the outer layer soup in an amount of about 0.1 to 3% by weight.

Other ingredients of the outer layer soup 2 according to the present invention can be ingredients used in soups and sauces for ordinary frozen foods. Examples include salt, sugar, sodium glutamate, sodium succinate, nucleic acid, protein hydrolysates, amino acids, citric acid, acidulants such as acetic acid, soy sauce, sake, mirin, oils and fats, animal and vegetable powders, animal and vegetable extracts, spices, colorings, and flavorings. It may also contain solids such as minced meat and cut vegetables. However, since the outer layer soup 2 comes into direct contact with the main food 3 of the frozen food, it is preferable to add as little ingredients such as dark soy sauce and colorings that may transfer color when in contact with the main food 3 as possible and to mix them in large amounts in the inner layer soup 1. By doing so, even if the soup melts due to a rise in temperature during frozen storage, color transfer from the outer layer soup 2 to the main food 3 can be prevented. In addition, even in frozen foods, the flavor deteriorates during frozen storage, so it is preferable to mix as many ingredients that deteriorate flavor as possible in the inner layer soup 1. Specifically, it is preferable for the mixture to contain crystalline substances such as salt and sugar, as well as viscosity-imparting materials such as starch, gelatin, and thickeners.

The viscosity of the inner layer soup 1 according to the present invention is not particularly limited, and it does not matter if it is viscous or not, as long as it is contained in the outer layer soup 2. However, it is preferable for the inner layer soup 1 to have some viscosity, as this reduces the possibility of the inner layer soup 1 mixing with the outer layer soup 2 during filling or freezing and spreading outside the outer layer soup 1. The preferred viscosity is about 0.2 Pa·s to 1250 Pa·s when filling.

The ingredients used in the inner layer soup 1 according to the present invention can be starch, gelatin, thickeners, as in the outer layer soup 2, or ingredients used in concentrated soups for ordinary frozen foods. Examples include salt, sugar, sodium glutamate, sodium succinate, nucleic acid, protein hydrolysates, amino acids, acidulants such as citric acid and acetic acid, soy sauce, sake, mirin, oils and fats, animal and vegetable powders, animal and vegetable extracts, spices, colorings, and flavorings. Solids such as minced meat and cut vegetables may also be included. However, it is preferable that the inner layer soup 1 contains more dark soy sauce and colorings that may transfer color than the outer layer soup 2. This can prevent color transfer from the outer layer soup 2 to the main ingredient 3 even if the soup melts due to a rise in temperature during frozen storage. It is also preferable that the inner layer soup 1 contains many ingredients whose flavor deteriorates during frozen storage, or whose flavor deteriorates or evaporates when heated in a microwave oven. Specifically, in the case of soy sauce ramen, it is preferable that flavoring ingredients such as dark soy sauce and caramel coloring, spices, flavorings, and animal and plant extracts are contained in the inner soup layer 2 rather than the outer soup layer 1.

It is preferable to add 50 to 150 g of the inner layer soup 1 and the outer layer soup 2 to one meal of the frozen food according to the present invention. If the amount added is small, it is difficult to concentrate the soup in the case of a concentrated soup, and if the amount added is too large, it takes a long time to thaw. The weight of the outer layer soup 2 is preferably about 2 to 10 times the weight of the inner layer soup 1. If the amount of the outer layer soup 2 is too small, there is a high possibility that the inner layer soup 1 will fall out of the outer layer soup 2. Also, when the frozen food soup A' is directly filled into the main ingredient 3 as in the frozen food B' shown in Figures 5 and 6, there is a high possibility that the outer layer soup 2 will drip from the gap in the main ingredient 3, causing the inner layer soup 1 to partially come into contact with the main ingredient 3. Conversely, if the amount of the outer layer soup 2 is too large, it is not preferable because it takes a long time to thaw during cooking or to dissolve the soup in hot water.

The frozen food soup according to the present invention may be used by freezing only the soup for frozen foods as in the case of frozen food soup A shown in Figures 1 and 2 and then adding it to the main food ingredient 3 as shown in Figure 3, or by directly filling the main food ingredient 3 as in the case of frozen food soup A' shown in Figures 5 and 6. When only the soup for frozen foods is frozen as in the case of frozen food soup A, it may be placed in a freezing form and frozen in a wagon freezer or spiral freezer, or the soup for frozen foods may be filled on a conveyor without being placed in a form and frozen in a spiral freezer or tunnel freezer. There are no particular limitations on the freezing temperature, but it is sufficient to freeze until at least the outer layer of the soup is firmly frozen.

The frozen food soup according to the present invention may be a concentrated soup for ramen, udon, soba, etc. that can be eaten by pouring boiling water over it after cooking in a microwave oven, or it may be a soup that can be eaten by adding water and cooking in a pot to dissolve the soup, or it may be a straight soup (or sauce) for ramen with thickened sauce, pasta, etc. that can be eaten as is after cooking in a microwave oven. In the case of ramen, udon, soba, etc., the viscosity of the outer layer soup is expressed mainly by starch, and the viscosity of the soup at the time of eating can be reduced by pouring boiling water over it or cooking in a pot.

There are no particular limitations on the method for producing the frozen food soup according to the present invention. The method may involve filling a container with the outer layer soup, then creating a depression in the center and filling it with the inner layer soup, and then placing the outer layer soup on top to enclose it, or it may involve inserting a nozzle into the center of the outer layer soup filled in the container, filling it with the inner layer soup, and then blocking the nozzle hole with the outer layer soup, or it may be produced using a two-liquid filling nozzle, which will be described later.

In this invention, "encompassing" does not only mean that the inner layer soup is completely contained within the outer layer soup, but also that most of the inner layer soup is enveloped in the outer layer soup, and also includes cases where part of the inner layer soup unintentionally leaks out of the outer layer soup due to expansion during filling or freezing. In most cases, this occurs on the top surface side of the soup for frozen foods, so even if part of the inner layer leaks out of the outer layer, it does not come into direct contact with the main ingredient 3, and so there is no major problem.

(2) Frozen Foods The frozen foods of the present invention are not particularly limited as long as they contain soup A for frozen foods or soup A' for frozen foods of the present invention and main food ingredient 3, as shown by frozen foods B, B', and B" in Figs. 4, 6, and 9, and examples thereof include frozen udon, frozen soba, frozen Chinese noodles, frozen pasta, frozen fried noodles with thickened sauce, frozen ramen with thickened sauce, and frozen fried bread with thickened sauce. Of these, frozen noodles such as frozen udon, frozen soba, and frozen ramen, which have a low viscosity soup when eaten and use concentrated soup, often pose a problem of color transfer to the main food ingredient 3 when concentrated soup is directly filled, and are therefore suitable as frozen foods that use the soup for frozen foods of the present invention. In other words, in order to prevent color transfer to the main food ingredient 3, the amount of components that transfer color to the outer layer soup 2 that is in direct contact with the main food ingredient 3 is reduced, and a large amount of components that transfer color to the inner layer soup 1 is blended, thereby preventing the transfer of color components to the noodles during frozen storage or cooking in a microwave oven, etc.

The main ingredient 3 may be noodles such as soba, udon, ramen, macaroni, spaghetti, pasta, glass noodles, rice vermicelli, hiyashi noodles, or cooked rice such as fried rice. It is preferable to fill 150 to 250 g of the main ingredient 3 per serving of frozen food after heating and cooking it in the usual manner.

For example, when the main ingredient 3 of the frozen food according to the present invention is noodles, raw noodles or dried noodles produced by a conventional manufacturing method can be used. Raw noodles or dried noodles are gelatinized by boiling or steaming. Since the frozen food according to the present invention is cooked when eaten, it is preferable to make the noodles partially incomplete by shortening the time rather than boiling or steaming them to a level that allows them to be completely eaten. For example, the boiling temperature is about 95 to 100°C, and the boiling time is usually about 20 seconds to 5 minutes for ramen and about 4 to 20 minutes for udon. As a method of steaming, heating with not only saturated steam but also superheated steam can be used, and a hydration step such as showering or soaking can be combined. The cooked noodles can be washed and cooled or soaked in seasoning liquid as necessary. The cooked noodles are filled into a freezing container 5 and frozen.

When the main ingredient 3 of the frozen food according to the present invention is cooked rice, cooked rice may be packed into the freezing container 5 in a conventional manner and frozen, or frozen cooked rice prepared by bulk freezing in a conventional manner may be packed into the freezing container 5 and frozen.

The thickness of the main ingredient 3 after freezing is preferably 20 mm or more. If it is less than 20 mm, the frozen food soup that melts during microwave cooking may fall to the bottom and burn. It is preferably 25 mm or more, and more preferably 30 mm or more. Conversely, if the main ingredient 3 is too thick, the cooking time will be longer and uneven cooking will occur, so it is preferably 50 mm or less.

Furthermore, if the density is too low, the soup for the frozen food will not remain on the upper surface of the main food ingredient 3 and will drip off during microwave cooking, so the packing density of the main food ingredient 3 in the present invention is preferably at least 0.3 g/ ^cm3 . More preferably, it is at least 0.4 g/ ^cm3 . Furthermore, if the density is too high, microwave cooking will take a long time, so a packing density of 0.6 g/ ^cm3 or less is preferable. The noodle block density can be calculated by cutting the flat surface of the frozen noodle block into a square with sides of 10 to 20 mm, taking the average length (height) of the four sides of the cut surface as the height of the sample, and calculating the volume of the cut sample.

The shape of the main ingredient 3 of the frozen food according to the present invention is not particularly limited, and may be a truncated cone, a truncated square pyramid, a cylindrical shape, or a square prism shape. In addition, as shown in Figures 7, 8, and 9, a depression may be provided in the center of the bottom surface of the main ingredient. By providing a depression, unevenness in microwave cooking can be reduced, and the microwave cooking time can be shortened. The depth of the depression depends on the thickness of the main ingredient 3, but is preferably 5 mm or more, and is preferably 10 to 70% of the thickness of the main ingredient 3.

The frozen food of the present invention may be prepared by adding a separately prepared soup A for frozen food to a main ingredient 3 and freezing it, as in the case of frozen food B shown in Figures 3 and 4, or by adding a separately prepared soup A for frozen food to a frozen main ingredient 3.

The frozen food according to the present invention may also be one in which the soup A' for frozen food is directly filled on the main ingredient 3, as in the frozen food B' shown in Figs. 5 and 6. The method of producing the frozen food B' is as follows: the main ingredient 3 is filled in the freezing container 5 as shown in Fig. 10(b), then the outer layer soup 2 is filled from the outer layer nozzle 7 of the two-liquid filling nozzle 8 as shown in Figs. 10(c) and (d), while the inner layer soup 1 is filled from the inner layer nozzle 6 after a delay, as shown in Figs. 10(c) and (d), the filling of the inner layer soup 1 from the inner layer nozzle 6 is stopped as shown in Fig. 10(e), and then the filling of the outer layer soup 2 from the outer layer nozzle 7 is stopped as shown in Fig. 10(f), thereby directly filling the soup A' for frozen food, in which the inner layer soup 1 is contained in the outer layer soup 2, on the main ingredient 3. The freezing container 5 in which the soup A' for frozen food is directly filled on the main ingredient 3 is frozen in a freezer or the like as shown in Fig. 10(g). At this time, it takes time to completely freeze, but it is preferable that the soup A' for frozen food does not drip from the main ingredient 3 during that time. Once completely frozen, frozen food B' can be produced by removing it from the freezing container 5 as shown in FIG. 10(h).

Furthermore, the frozen food according to the present invention can have a surface layer 4 of heat-resistant amylase attached to the main ingredient 3, as in the case of frozen food B" shown in Figures 7, 8 and 9. By adding heat-resistant amylase to frozen food B", if the viscosity of the outer layer soup 2 of frozen food soup A' is based on starch, pouring hot water over it will cause the heat-resistant amylase attached to the main ingredient 3 to break down the starch in the outer layer soup 2, lowering the viscosity of the soup when eaten, allowing it to become a food with a low-viscosity soup, such as udon, soba or ramen.

The term "thermostable amylase" as used herein refers to an amylase with an optimum temperature of approximately 70°C or higher. The optimum temperature of ordinary enzymes is approximately 30°C to 50°C, and the optimum temperature of the thermostable amylase is in a higher temperature range. There is no particular limitation on the type of thermostable amylase. In other words, either α-amylase or β-amylase can be used, but α-amylase is preferred because it has a faster starch decomposition rate. These amylases may be extracted from organisms such as bacteria, plants, and animals, or mass-produced using genetic engineering techniques. Specific examples of such products include Clystase (registered trademark) T10S, Clystase (registered trademark) SD8, and Kokugen SD-TC3, all of which are manufactured by Amano Enzyme Co., Ltd. The thermostable amylase that can be used in the present invention may be in the form of a solid powder or liquid.

The amount of thermostable amylase in the surface layer 4 containing the thermostable amylase according to the present invention is such that, when the amount of soup at the time of consumption is 250g to 350g, the thermostable amylase is added so that the soup at the time of consumption contains approximately 15U or more. If 15U or more is contained, the starch contained in the soup for frozen foods according to the present invention can be decomposed. There is no particular upper limit, but adding more than 200U may affect the texture of the noodles. Specifically, it is preferable to add about 5 to 50g of an aqueous solution containing 1.5U/g to 20U/g of thermostable amylase per serving of the frozen food according to the present invention.

In the method of producing frozen food B" according to the present invention, a freezing container 5 with a convex bottom center as shown in FIG. 11(a) is filled with a main ingredient 3 as shown in FIG. 11(b), and then directly filled with soup A' for frozen food as shown in FIGS. 11(c) to (f). Then, a thermostable amylase aqueous solution 9 is filled on the side of the freezing container 5 as shown in FIG. 11(f), and an ice layer 4 containing thermostable amylase is produced by freezing as shown in FIG. 11(g). Then, the container is removed from the freezing container 5 as shown in FIG. 11(h), thereby producing frozen food B". The thermostable amylase aqueous solution may be filled before filling with the main ingredient 3, or after filling with the main ingredient 3 and before filling with soup A' for frozen food. Although the freezing container 5 has a convex bottom center, the freezing container 5 may have a flat bottom center as shown in FIG. 10.

Other ingredients such as roasted pork fillets, bamboo shoots, spinach, tempura, deep-fried tofu, and fried tempura bits can be added to the frozen food of the present invention. The ingredients may be added by adding pre-frozen ingredients to the frozen food, or by adding the ingredients when freezing the main ingredient 3 and freezing them together.

If the frozen food is to be cooked in a microwave oven, it can be packaged in a microwaveable bag or container and sold commercially. If it is to be cooked in a pot, it can be packaged in a cold-resistant plastic film, or the frozen food of the present invention can be placed in an aluminum dish that can be cooked over an open flame and then packaged in a freezing-resistant plastic film and sold commercially.

(3) Cooking The cooking method of the frozen food according to the present invention is not particularly limited, and it can be eaten by cooking in a microwave oven or cooking in a pot. When the frozen food is cooked in a microwave oven, such as rice, pasta, fried noodles with thickened sauce, fried noodles, or fried udon, it can be eaten as is after cooking in the microwave oven. When udon, soba, or ramen is cooked in a microwave oven, it can be easily eaten by transferring it to a bowl, pouring hot water over it, and stirring it. When udon, soba, or ramen is cooked in a pot, it can be eaten by pouring water or hot water into a pot or aluminum dish and heating it.

At this time, the frozen food soup according to the present invention has a high viscosity of 250 Pa·s or more at 60°C even when heated by microwave cooking, so as shown in FIG. 12, the frozen food soup does not fall onto the main ingredient 3 even when heated, and the inner layer soup 1 does not dissolve out of the outer layer soup 2. Therefore, the frozen food soup does not burn, and by incorporating a large amount of ingredients that may transfer color into the inner layer soup 1, color transfer from the frozen food soup to the main ingredient 3 during cooking can be prevented.

In addition, when the frozen food B" according to the present invention contains a heat-resistant amylase, the starch contained in the outer layer soup 2 of the frozen food soup is dissolved by pouring boiling water after cooking with heat such as in a microwave oven, so that the viscosity of the soup at the time of eating can be reduced.

As described above, by making the soup for frozen foods have a two-layer structure in which the inner layer soup is enclosed by the outer layer soup, making the viscosity of the outer layer soup at the time of filling 270 Pa·s or more, and making the viscosity of the outer layer soup at 60°C 250 Pa·s or more, it is possible to fill the concentrated soup directly into the main ingredient of the frozen food, reducing packaging materials and providing a frozen food soup that allows for simple cooking, and a frozen food that contains the said soup for frozen foods. Furthermore, even when colored concentrated soup such as soy sauce ramen is directly filled into the frozen food, it is possible to provide a soup for frozen foods and a frozen food that contains the said soup for frozen foods that causes little transfer of the soup color to the food during freezing and cooking.

The following examples will explain this embodiment in more detail.

(Preparation of frozen food soup for each test group)
The ingredients for soup in each test batch shown in Table 1 below were placed in a tank in the order of water, powder, and liquid, and thoroughly stirred. The tank was then heated and thoroughly stirred, and after reaching a temperature of 90°C, the temperature was maintained while stirring for 10 minutes, and then cooled to 35°C. The viscosity of the soup (each layer soup in the case of a two-layer soup) at 35°C was measured. The viscosity of the soup (each layer soup in the case of a two-layer soup) at 60°C was also measured. The viscosity was measured with a B-type viscometer, and for samples containing 3% by weight of hydroxypropyl phosphate cross-linked starch, the measurement was performed with rotor No. 1 at 12 rpm, and for the other samples, the measurement was performed with rotor No. 4 at 0.3 rpm.

Example 1
A mixing solution of 10 g of salt and 10 g of kansui preparation (sodium carbonate 50: potassium carbonate 45: polymerized phosphate 5) dissolved in 350 ml of water was added to a raw material flour made by mixing 950 g of wheat flour and 50 g of starch, and the mixture was kneaded in a mixer for 15 minutes to prepare a noodle dough. This was rolled out with a roll to produce a noodle band with a thickness of 1.5 mm, and cut out with a cutting blade (square blade) of No. 20 to produce raw noodle strands. The obtained raw noodle strands were then cut into one serving of 25-30 cm (weight 116 g/serving), boiled in boiling water for 30 seconds, washed in cold water for 1 minute, immersed in ice water for 30 seconds, cooled, and drained to produce cooked noodles (ramen).

Next, 170 g of cooked noodles were packed into a freezing container (container opening diameter: 150 mm, container bottom diameter: 140 mm, container height: 54 mm, container convex opening diameter: 108 mm, container convex bottom diameter: 96.5 mm, container convex height: 8 mm), and then a two-fluid nozzle was used to pack the cooked noodles into the center of the top surface of the noodle block so that the inner layer soup described in Example 1 of Table 1 was encompassed by the outer layer soup (noodle density: 0.46 g/cm ³ , noodle block thickness: 30 mm). Next, 10 g of a solution in which Kleistase (registered trademark) T10S (1700 U/g) was dissolved to a concentration of 0.3 wt % as a heat-resistant amylase was packed into the freezing container, and the solution was placed in an air blast type quick freezer at -35°C for 45 minutes and then removed from the tray to produce a frozen food (soy sauce ramen) as shown in Figures 7, 8 and 9. The frozen food thus prepared was placed in a bag for microwave cooking to prepare a test sample.

Example 2
Test samples were prepared according to the method of Example 1, except that the inner layer soup and outer layer soup described in Example 2 in Table 1 were filled.

Example 3
Test samples were prepared according to the method of Example 1, except that the inner layer soup and outer layer soup described in Example 3 of Table 1 were filled.

Example 4
Test samples were prepared according to the method of Example 1, except that the inner layer soup and outer layer soup shown in Example 4 in Table 1 were filled.

Example 5
Test samples were prepared according to the method of Example 1, except that the inner layer soup and outer layer soup shown in Example 5 in Table 1 were filled.

Example 6
Test samples were prepared according to the method of Example 1, except that the inner layer soup and outer layer soup described in Example 6 in Table 1 were filled.
(Comparative Example 1)
A test sample was prepared according to the method of Example 1, except that the concentrated soup described in Comparative Example 1 in Table 1 was filled from the inner layer nozzle of the two-liquid nozzle and no heat-resistant amylase solution was added.

(Comparative Example 2)
Test samples were prepared according to the method of Comparative Example 1, except that the concentrated soups shown in Comparative Examples 2 and 3 in Table 1 were filled from the inner layer nozzle of the two-liquid nozzle.

(Comparative Example 3)
Test samples were prepared according to the method of Example 1, except that the concentrated soups shown in Comparative Examples 2 and 3 in Table 1 were filled from the inner nozzle of the two-liquid nozzle.

(Comparative Example 4)
A test sample was prepared in the same manner as in Example 1, except that the inner layer soup and outer layer soup shown in Comparative Example 4 in Table 1 were filled.

Each test example frozen noodle sample was cooked and evaluated. The cooking method was to cook the test example sample in a microwave oven at 500W for 5 minutes and 30 seconds, then transfer it to a bowl, pour in 250g of boiling water, and stir the soup and noodles. Evaluations were performed on dripping of soup when filled, the containment of the inner layer of soup for the two-layer soup, color transfer to the noodles during cooking, dripping of soup, and the solubility and viscosity of the soup. Each sample was also cooked after being abused, and color transfer after cooking was evaluated. Abuse treatment involved storing the samples in a refrigerator at -18°C for 14 days, with the temperature inside the refrigerator being raised to 5°C over 30 minutes and then lowered to -18°C over 30 minutes, with this treatment performed every 6 hours.

The evaluation method was a four-point scale. Regarding dripping of soup during filling, those that hardly dripped into the inside of the noodle block were rated as ◎, those that dripped into the inside of the noodle block but only slightly (the inner layer of soup was not in contact with the noodle block) were rated as ○, those that did not drip onto the microwave packaging but dripped deep into the noodle block (the inner layer of soup was in contact with the noodle block) were rated as △, and those that dripped onto the microwave packaging were rated as ×.

The two-layer soup was evaluated for the inclusion of the inner layer. The inner layer soup was very well included in the outer layer soup, and was marked with an ◎. The inner layer soup was included in the outer layer soup, and was marked with an ○. The inner layer soup was partially leaking out of the outer layer soup, and the inner layer soup was mostly leaking out of the outer layer soup, and was marked with an ×.

Regarding color transfer during cooking, the following criteria were given: ◎: no color transfer to the noodle strings at all; ○: very little or only slight color transfer to the noodle strings; △: some color transfer to the noodles that was noticeable; ×: significant and noticeable color transfer to the noodles.

Regarding dripping of soup during cooking, those that barely dripped into the noodle block after microwave cooking were marked with an ◎, those that dripped into the noodle block but did not drip onto the bottom of the noodle block were marked with an ○, those that dripped slightly onto the bottom of the noodle block but did not drip onto the microwave packaging were marked with a △, and those that dripped onto the microwave packaging were marked with an ×.

Regarding the viscosity and solubility of the soup during cooking, those that dissolved in hot water and had almost the same viscosity as the soup when cooked with the soup provided separately were rated as ◎, those that dissolved in hot water and had a slightly higher viscosity than the soup when cooked with the soup provided separately but were generally good were rated ○, those that were difficult to dissolve in hot water and had a high and inferior viscosity when cooked with the soup provided separately were rated △, and those that were difficult to dissolve in hot water and had a significantly higher viscosity when cooked with the soup provided separately and were unacceptable were rated ×.

In addition, samples that had been subjected to abusive treatment were cooked in the same manner and the color transfer during cooking was evaluated.

The sensory evaluation results for each test example are shown in Table 2 below.

As shown in Comparative Example 1, when ordinary concentrated soup was filled as is, the soup dripped from the noodle block when it was filled, and not only did the color transfer to the noodles during cooking, but the soup also burned, resulting in a poor flavor. Furthermore, as shown in Figure 13, the mistreatment process caused the color of the soup to transfer even more to the noodles.

As shown in Comparative Example 2, by imparting viscosity to the soup mainly through starch, the soup does not drip when filled or when cooked, and this helps to prevent color transfer to the noodle strings and flavor deterioration due to burning. However, the soup has poor solubility when dissolved in hot water, and the viscosity of the soup increases due to the starch.

As shown in Comparative Example 3, by attaching an ice layer of heat-resistant amylase to the noodle block, the solubility of the soup during cooking was improved compared to Comparative Example 2, and the starch in the soup was broken down, resulting in almost no viscosity. However, as shown in Figure 14, when the noodle block was subjected to abuse treatment, the noodle block was in direct contact with the soup containing dark soy sauce and caramel coloring, and as the product temperature rose, the soup dissolved and color transfer occurred, which is thought to be why color transfer occurs during frozen storage.

In response to this, as shown in Examples 1 to 6, by making the soup for frozen foods into two layers and filling the inner layer with dark soy sauce or caramel coloring, which are prone to color transfer, it is possible to prevent color transfer not only during cooking but also during abuse, as shown in Figure 12, and therefore it is believed that color transfer during frozen storage can also be prevented.

However, as shown in Comparative Example 4, when the amount of starch added to the outer layer soup is low and the viscosity is low, it is difficult for the outer layer soup to contain the inner layer soup when filling, and the soup falls into the inside of the noodle block, which not only causes color transfer during cooking, but also transfers the color of the soup to the noodles when the noodle is mistreated. Therefore, it is considered that the viscosity of the outer layer soup when filling is 270 Pa·s or more, more preferably 550 Pa·s or more. It is also considered that the starch content is 5% by weight or more, more preferably 7% by weight or more. Conversely, as shown in Example 5, when the amount of starch added to the outer layer soup is high and the viscosity is high, the solubility in boiling water is poor and it takes a long time to decompose with heat-resistant amylase, resulting in a high viscosity of the soup. It is also difficult to fill, so it is considered that the starch content is 15% by weight or less, more preferably 12% by weight or less, and the viscosity when filling is 2000 Pa·s or less, more preferably 1610 Pa·s or less.

As shown in Example 6, when the weight of the outer layer soup is small relative to the weight of the inner layer soup, the inclusion during filling is poor, the inner layer soup is more likely to come into contact with the noodle block, and color transfer is more likely to occur. Therefore, it is considered preferable that the amount of outer layer soup encompasses the inner layer soup by at least two times. However, the more the amount of outer layer soup is increased, the heavier the soup for frozen foods becomes, which not only takes longer to thaw, but also requires more enzymes to break down the starch, so it is considered preferable that the amount is substantially 10 times or less.

Claims (10)

A soup for frozen food having a two-layer structure used for frozen food including a main ingredient and soup ,
The two-layer structure is a structure in which an inner layer soup is enclosed by an outer layer soup,
the viscosity of the outer layer soup at the time of filling is 270 Pa s or more,
The viscosity of the outer layer soup at 60°C is 250 Pa s or more,
The outer layer soup contains at least starch as an ingredient for adjusting viscosity . 2. The soup for frozen food according to claim 1, wherein the starch comprises at least one of phosphate cross-linked starch, hydroxypropyl phosphate cross-linked starch, or acetylated phosphate cross-linked starch. 3. A soup for frozen foods according to claim 1 or 2, characterized in that the amount of said starch added is 5 to 15% by weight based on the weight of the outer layer soup. The soup for frozen foods according to any one of claims 1 to 3, characterized in that the weight of the outer layer soup in the soup for frozen foods is at least twice the weight of the inner layer soup. The soup for frozen food according to any one of claims 1 to 4, characterized in that the inner layer soup contains more pigment components than the outer layer soup. 6. The soup for frozen foods according to claim 1, wherein the soup for frozen foods is filled directly on top of the main ingredient. A frozen food comprising the soup for frozen food according to any one of claims 1 to 6 and a main ingredient . The frozen food according to claim 7, characterized in that the main ingredient is noodles or rice .
The frozen food according to claim 7 or 8, characterized in that the frozen food contains a heat-resistant amylase. A method for producing soup for frozen food used in frozen food including a main ingredient and soup , comprising:
The soup for frozen food is produced using a two-liquid filling nozzle so that the soup has a two-layer structure in which an inner layer soup is enclosed by an outer layer soup,
the outer layer soup has a viscosity of 270 Pa s or more when filled and a viscosity of 250 Pa s or more at 60° C.,
2. A method for producing soup for frozen foods , wherein the outer layer soup contains at least starch as a raw material for adjusting viscosity .

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