Pregelatinized starch and method for producing same

Abstract

Provided is a pregelatinized starch having a gelatinization degree of 13.0 or more and an advancing distance of 3.30 cm or less.　The gelatinization degree is a ratio Wf / Ws of a gel generation quantity Wf when the pregelatinized starch is mixed with 100 times the mass thereof of water and a quantity Ws of the pregelatinized starch before mixing, and the advancing distance is the movement distance of 10 g of a gel obtained by mixing water and the pregelatinized starch in a manner in which the moisture content of the obtained gel becomes 90.9 mass%.　The present invention further provides a heated-dough food product using the pregelatinized starch and a bakery food product obtained by heating a batter including the pregelatinized starch.

Description

Pregelatinized starches and their manufacturing method

[0001] The present invention relates to pregelatinized starches suitable for food applications.

[0002] Pregelatinized starch is made by heating raw starch in the presence of water to gelatinize it (gelatinize it). Pregelatinization disrupts the molecular arrangement inside the starch granules, resulting in irreversible changes in properties such as swelling of the starch granules, loss of birefringence, melting of natural microcrystals, and solubilization of the starch. For this reason, pregelatinized starch exhibits unique properties that differ from raw starch, and is widely used in food and industrial applications.

[0003] On the other hand, due to recent changes in consumer preferences and lifestyles, there is a demand for foods that have a moist texture and improved resistance to changes in texture over time. To prevent dryness due to aging, a well-known method is to replace part of wheat flour, a main ingredient of bread, with pregelatinized starch (see, for example, Patent Document 1). However, the conventional pregelatinized starch described in Patent Document 1 did not provide sufficient aging resistance.

[0004] Japanese Patent Application Publication No. 59-175845

[0005] Therefore, an object of the present invention is to provide a pregelatinized starch that can impart superior retrogradation resistance and an excellent moist texture to foods compared to conventional products.

[0006] The present invention provides pregelatinized starches having a gelation degree of 13.0 or more and a travel distance of 3.30 cm or less, wherein the gelation degree is the ratio Wf / Ws of the amount of gel produced when the pregelatinized starch is mixed with 100 times the mass of water, Wf, to the amount of pregelatinized starch before mixing, Ws, and the travel distance is the distance traveled by 10 g of a gel obtained by mixing water and pregelatinized starch so that the water content of the resulting gel is 90.9 mass%.

[0007] The present invention also provides a method for producing pregelatinized starches, comprising a step of adding water to a raw material starch and heating the raw material starch, wherein the amount of water added in the step is 150 parts by mass or more per 100 parts by mass of the raw material starch, and the heating temperature is 90°C or more and 165°C or less.

[0008] The pregelatinized starches of the present invention have a gelatinization degree of 13.0 or more and a progress distance of 3.30 cm or less.

[0009] In this specification, "starch" is a concept that includes starch and cereal flour containing starch as the main component, and is a powdery substance at room temperature and normal pressure. "Starch" here refers to "pure starch" isolated from plants such as wheat, and is distinguished from starch that is inherently present in cereal flour or whole grain flour. Hereinafter, when "starch" is used in this specification, whether it refers to pure starch or includes starch that is inherently present in cereal flour or whole grain flour will be determined depending on the context.

[0010] The grains from which "starch" is derived include cereals (seeds of grass plants), pseudocereals (seeds of dicotyledonous plants), pulses (seeds of legumes), and potatoes (edible tuberous roots or stems), which contain starch as an ingredient.

[0011] Specific examples of flour include flours primarily composed of endosperm, such as wheat flour (specifically, for example, strong flour, medium flour, soft flour, durum wheat flour, and durum semolina), rice flour, buckwheat flour, rye flour, soy flour, barley flour, and corn flour, as well as flours containing at least the outer layer and the germ, such as "whole wheat flour" containing the three main components of the outer layer and the germ. Specific examples of whole wheat flour include whole wheat flour. Specific examples of starch include potato starch, wheat starch, corn starch, waxy corn starch, rice starch, and tapioca starch.

[0012] In the present invention, of starches and cereal flours, starch is preferably used as the raw starch for the pregelatinized starches, because the above-mentioned gelation degree and progression distance can be successfully obtained and handling is easy due to the absence of foaming of the slurry.

[0013] In particular, in the present invention, it is preferable to use starch with an amylose content of less than 5% as the starch used as the raw material for pregelatinized starches, since foods using the pregelatinized starch of the present invention have a moist texture (hereinafter also referred to as "moistness") and excellent retrogradation resistance. Starch with an amylose content of less than 5% is usually starch with an amylopectin content of more than 95%. A high content of highly branched amylopectin allows it to hold a large amount of water, making it easy to increase the degree of gelation. It has been found that by using such a starch that easily holds water and producing pregelatinized starches with a certain degree of gelation or more and a certain progression distance or less, it is possible to obtain particularly excellent moist texture and retrogradation resistance. An example of a starch with an amylose content of less than 5% is glutinous rice starch. Examples of glutinous starch include those derived from corn, rice, potatoes, etc., but waxy cornstarch is particularly preferred because it can be hydrated and heated under specific conditions to give foods containing pregelatinized starch a particularly excellent moist feel and aging resistance.

[0014] The pregelatinized starches of the present invention and their raw material starches are preferably not chemically modified. Conventionally, chemically modified starches such as phosphate cross-linked starch and hydroxypropyl etherified phosphate cross-linked starch have been known as modified starches for retrogradation resistance. However, these are food additives, and due to the recent increase in awareness of clean labels, they tend to be disliked by consumers. In contrast, if the pregelatinized starches of the present invention are not chemically modified, they will exhibit excellent retrogradation resistance while not being considered food additives, making them more acceptable to consumers who avoid food additives, and are therefore preferred. Furthermore, the method for producing pregelatinized starches of the present invention, which will be described later, has the advantage of being able to impart excellent retrogradation resistance to starches without using chemically modified starch. Chemical modification is a process in which a chemical agent is applied to starch to introduce a modifying group. Examples of chemically modified starches include acetylated adipic acid cross-linked starch, acetylated phosphate cross-linked starch, acetylated oxidized starch, sodium octenylsuccinate starch, acetate starch, oxidized starch, hydroxypropyl starch, hydroxypropylated phosphate cross-linked starch, phosphorylated monoesterified phosphate cross-linked starch, phosphorylated starch, phosphate cross-linked starch, etc., which are designated as food additives. It is preferable that the pregelatinized starches are not oil- or fat-processed starches.

[0015] The pregelatinized starches of the present invention have a gelatinization degree of 13.0 or more and a progression distance of 3.30 cm or less. As a result of extensive investigations into the composition of pregelatinized starches that can impart better retrogradation resistance and a moist feel to foods than conventional ones, the present inventors have found that the above-mentioned problems can be solved by combining specific parameters related to the degree of hydration and fluidity of pregelatinized starches.

[0016] The degree of gelation is the ratio Wf / Ws of the amount of gel produced when pregelatinized starches are mixed with 100 times the mass of water, Wf, to the amount of pregelatinized starches before mixing, Ws. The pregelatinized starches of the present invention are thus excellent in their ability to hold a large amount of water and gel, and the inventors have discovered that pregelatinized starches with a degree of gelation of 13.0 or higher can effectively impart a moist texture to foods containing the pregelatinized starches, even after heating. To further enhance the effect of improving moist texture, the degree of gelation of the pregelatinized starches of the present invention is preferably 13.2 or higher, and particularly preferably 13.5 or higher. Furthermore, a degree of gelation of, for example, 30.0 or lower is preferred, as it provides a smooth and soft texture. The degree of gelation is measured by the following method.

[0017] <Method for measuring gelation degree> The weight (We) of a 2 ml Eppendorf tube is measured. 1.5 ml of ion-exchanged water (25°C) is poured into the Eppendorf tube after the weight measurement, and then 0.015 g (Ws) of pregelatinized starch is added in dry weight equivalent. After adding the pregelatinized starch, the Eppendorf tube is closed and immediately vortexed to remove any lumps. The vortexed Eppendorf tube is centrifuged in a centrifuge for 30 minutes at 10°C and 15,000 rcf. After removing the Eppendorf tube from the centrifuge, the lid is removed, the supernatant is discarded, and the weight (Wg) of the Eppendorf tube is measured. Carefully handle the Eppendorf tube after centrifugation without shaking. The gelation degree is calculated using the following formula. The gelation degree is the average value of six or more replicate measurements for each sample. (Gelation degree)=(Wg-We) / Ws Wg-We in the above formula corresponds to the amount of gel formation Wf.

[0018] The dry weight refers to the weight of, for example, 3.0 g of pregelatinized starch dried at 135°C for 1 hour. The supernatant can be discarded by tilting the tube with the lid open by 60° in a vertical position with the lid facing up, and then aspirating the supernatant using a pipette. It is preferable to use a pipette tip of 100 μl or less. The vortexing should be performed for 10 seconds.

[0019] Furthermore, the pregelatinized starches of the present invention have a moving distance of 3.30 cm or less. Here, the moving distance refers to the distance traveled by 10 g of a gel obtained by mixing water and pregelatinized starches so that the resulting gel has a moisture content of 90.9% by mass. A moving distance of less than a certain level despite a high degree of gelation indicates that the fluidity of the gel containing a predetermined amount of water is low, i.e., that the gel has a high water-holding capacity and excellent gelling performance (gel shape retention). Therefore, pregelatinized starches having a degree of gelation greater than a certain level and a moving distance less than a certain level are considered to be capable of holding a large amount of water and to have excellent water-holding properties. The present inventors have found that when pregelatinized starches having a degree of gelation greater than a certain level and a moving distance less than a certain level are used in foods, they impart excellent moistness and aging resistance even after heating. In the present invention, the moving distance of the pregelatinized starches is 3.30 cm or less, preferably 3.27 cm or less, and more preferably 3.24 cm or less. It is particularly preferable that the advance distance of the pregelatinized starch is 0.3 cm or more.

[0020] Specifically, the traveled distance is measured in the following manner.

[0021] <Method for Measuring the Distance Traveled> Water (25°C) and pregelatinized starches were placed in a container so that the total weight of the resulting gel was 55 g and the moisture content of the gel after hydration was 90.9% by mass, and the mixture was stirred 50 times with a hand whisk. After stirring, the mixture was left at room temperature (25°C) for 10 minutes, and then 10 g of the gel was filled into a 15 ml centrifuge tube (inner diameter: 15 mm) and centrifuged (30 min, 10°C, 3500 rpm). After centrifugation, the tube was handled carefully without shaking. The lid of the centrifuge tube was removed and the travel distance was measured when the tube was placed flat (the vertical scale being set to 0). Specifically, the distance traveled by the gel from the bottom to the top of the centrifuge tube was measured when the tube was placed horizontally. The travel distance was measured four or more times for each sample, and the average value was used.

[0022] When removing the lid of the centrifuge tube and placing it flat, tilt the vertical centrifuge tube by 90° and then lay it on its side. The operation of tilting the vertical centrifuge tube by 90° is preferably performed at a rate of 10° / sec to 30° / sec, and the tube is gently placed on its side on a horizontal surface. The travel distance is measured 30 seconds after the vertical centrifuge tube is laid on its side. The travel distance is measured at room temperature (25°C). The rotation speed when stirring 50 times with a hand whisk is 150 rpm, and each stirring takes 0.4 seconds. The hand whisk can be manufactured by Kotobuki Seiki Co., Ltd., but is not limited to this.

[0023] The centrifuge tube used is specifically a product of IWAKI Corporation called "15mL 2325-015-MYP" (made of polypropylene), but tubes of the same shape and material may also be used.

[0024] In the present invention, the average particle size of the pregelatinized starches is preferably 15.0 μm or more, more preferably 20.0 μm or more. The average particle size of the pregelatinized starches is preferably 700.0 μm or less, more preferably 65.00 μm or less. The average particle size of the pregelatinized starches in each of the examples described below was within the range of 20.0 μm or more and 65.00 μm or less. In this specification, the term "average particle size" refers to the volume-cumulative particle size D50 at 50% by volume of the cumulative volume measured in a dry state using a laser diffraction / scattering particle size distribution analyzer (e.g., Microtrac S3500 manufactured by Microtrac Bell Co., Ltd.).

[0025] Next, a preferred method for producing pregelatinized starches of the present invention will be described. This production method comprises the steps of adding water to and heating raw starches, wherein the amount of water added in this step is 150 parts by mass or more per 100 parts by mass of the raw starches, and the heating temperature is 90°C or higher and 165°C or lower. The raw starches have been described above. As mentioned above, the raw starches are preferably starches with an amylose content of 5% or less, and waxy cornstarch is particularly preferred. The average particle size of the raw starches is preferably 5.0 μm or higher and 250 μm or lower, for example, because suitable gelation degrees and progression distances can be more easily achieved by the hydration and heat treatments. The average particle size of the raw starches in each of the examples described below was within the range of 5.0 μm or higher and 250 μm or lower.

[0026] The step of hydrating and heating raw starches refers to a step of simultaneously subjecting raw starches to hydration and heat treatment, or a step of adding water to raw starches in a hydration treatment and then subjecting the resulting hydrate to a heat treatment. The heat treatment causes the starch contained in the raw starches to become gelatinized starches, and the raw starches become pregelatinized starches. Therefore, the heat treatment is also called a gelatinization treatment. From the perspective of simplicity in the production process, the step of hydrating and heating raw starches is preferably a step of adding water to raw starches in a hydration treatment and then subjecting the resulting hydrate to a heat treatment.

[0027] In the hydration treatment, raw starches and water are mixed in a ratio of 150 parts by mass or more of water to 100 parts by mass of raw starch. By incorporating such a relatively large amount of water into the raw starch, which is the object to be heated, the side chains of the starch contained in the starch are more likely to open after heating at a predetermined temperature, and the side chains of the starch are less susceptible to damage caused by heating. As a result, the gelling and water-holding properties of the starch are improved, making it easier to obtain pregelatinized starches with a gelling degree equal to or greater than the specified value and a progression distance equal to or less than the specified value. If the amount of water added is less than 150 parts by mass per 100 parts by mass of raw starch, the effects of the present invention will not be achieved.

[0028] In the hydration treatment, the amount of water added per 100 parts by mass of raw starch is preferably 150 to 1,500 parts by mass, more preferably 150 to 1,200 parts by mass, and even more preferably 150 to 1,000 parts by mass. If the amount of water added is too large, a lot of time and energy will be required to obtain a solid product in the drying step after the hydration and heating step, which may result in increased production costs and reduced production efficiency. The temperature of the water used for hydration is not particularly limited, and may be in the range of 0°C to 100°C, for example. In the present invention, the above amount of water is typically added as liquid water.

[0029] The heat treatment must be carried out under conditions such that the product temperature of the hydrated raw starch is 90° C. or higher and 165° C. or lower. As described above, in the present invention, highly hydrated raw starches are prepared by adding 150 parts by mass or more of water to 100 parts by mass of raw starch, which is presumably what facilitates opening of the side chains of the starch contained in the raw starch and suppresses starch damage during heating, improving the degree of gelatinization while reducing the progression distance. By heating this highly hydrated raw starch under the above conditions, the gelling performance and water-holding performance of the resulting pregelatinized starches can be favorably improved, making it possible to produce pregelatinized starches with a degree of gelatinization of a certain level or higher and a progression distance of a certain level or lower.

[0030] When raw starches that have been hydrated to a certain amount or more are heated at a certain temperature or higher, starch modification progresses, making it easier to obtain pregelatinized starches of the present invention having a certain degree of gelation or higher. From this perspective, the product temperature of the raw starches during heating in the heating step of the hydrated raw starches is preferably 90°C or higher, more preferably 95°C or higher, and even more preferably 100°C or higher. Heating under conditions that result in a product temperature of the hydrated raw starches exceeding 100°C can be achieved, for example, by heating the hydrated raw starches in a pressurized atmosphere or on the surface of a heated iron plate or drum. Furthermore, if the heating temperature of the hydrated raw starches is too high, the starch gel shape retention function of the resulting pregelatinized starches will be impaired, and their gel performance will be reduced, resulting in a product that does not meet the requirements of the present invention for a certain degree of gelation or higher and a certain progression distance or less. From this perspective, the heating temperature in the heat treatment for heating the raw starches is preferably 165°C or lower, and more preferably 150°C or lower. In this specification, heating at a predetermined temperature refers to heating after gelatinizing the raw starch. Gelatinization of the raw starch can be determined by the transparency of the starch paste.

[0031] In the heat treatment, the heating time for the hydrated pregelatinized starch (the time for maintaining the product temperature) is not particularly limited, but may be, for example, 50 minutes or less, 40 minutes or less, or 30 minutes or less. Gelatinization is preferably carried out in the range of 90°C to 165°C. In the heat treatment, the time for maintaining the product temperature may be 0 minute, 1 minute or more, or 10 minutes or more. The time may be the time after the raw starch has been gelatinized.

[0032] In the hydration treatment, the slurry containing raw starches and water typically contains only raw starches and water as a solvent, but may also contain other components, such as a starch modifier that can be used in the pretreatment of the raw starches, as needed. The starch modifier is an agent that can modify starches to desired properties, and examples thereof include enzymes, acid or alkali agents, sugars, amino acids, peptides, thickeners such as thickening polysaccharides, etc. Examples of the enzyme include amylase and proteases that degrade proteins contained in starches. When the slurry contains components other than the raw starches and water, the amount of the other components is preferably 10 parts by mass or less, more preferably 3 parts by mass or less, even more preferably 1 part by mass or less, even more preferably 0.5 parts by mass or less, and particularly preferably 0.1 parts by mass or less, per 100 parts by mass of the raw starch.

[0033] Preferably, the step of adding water to and heating the raw starch includes a slurry preparation treatment in which water and the raw starch are mixed to prepare a slurry, and a slurry heating treatment (gelatinization treatment) in which the obtained slurry is heated, and the respective treatments are carried out in this order, which is preferable because it makes it easier to successfully obtain pregelatinized starches having the above-mentioned gelatinization degree and progression distance.

[0034] When the water addition and heating step includes a post-slurry preparation step and a slurry heating step, 1) a starch modifier identical to or different from the starch modifier may be added to a slurry containing starches pretreated with a starch modifier, or 2) a starch modifier may be added to a slurry containing starches not pretreated with a starch modifier. In a slurry containing a starch modifier, a reaction involving the starch modifier, such as an enzyme reaction, occurs, and this reaction may be completed before the slurry is subjected to the subsequent drying step, or may occur during the drying step.

[0035] The heating method in the heat treatment is not particularly limited as long as it can accommodate the conditions of high water content and high temperature. A typical heating method is a method in which a slurry containing starches is placed in a container and the container is heated. The slurry can be heated batchwise or continuously. Examples of the container in which the slurry is heated include a pressure cooker when a batchwise method is used and a line mixer such as a static mixer when a continuous method is used. The heating means is also not particularly limited, and examples include electric, gas, and steam types, and these can be used alone or in combination of two or more. An example of a method for heating a slurry using a steam heating means is a method in which saturated steam or superheated steam is directly introduced into a container containing the material to be dried (starch).

[0036] In the slurry heat treatment, it is preferable to stir the slurry while heating it. If the slurry is heated without stirring and left to stand, the starches contained in the slurry may form lumps, which may result in insufficient or uneven gelatinization of the starch. However, stirring the slurry during heating prevents such problems and promotes gelatinization of the starch. The method for stirring the slurry is not particularly limited as long as it can disperse the contained starches throughout the slurry. Typically, the stirring can be carried out according to a conventional method using a known vessel equipped with a stirrer, which is equipped with a vessel and a stirrer for stirring the contents of the vessel. For example, when the slurry is heated in a batchwise manner, an apparatus equipped with stirring blades can be exemplified, and when heated in a continuous manner, a static mixer can be exemplified. Furthermore, a known ultrasonic vibration generating means can be used as the slurry stirring means. In this case, the ultrasonic vibration generated by the ultrasonic vibration generating means generates fine bubbles in the slurry to stir the slurry. Alternatively, the slurry may be stirred during heating by blowing a gas such as steam into the slurry without using a stirring tool such as a stirring blade.

[0037] The slurry heat treatment is preferably completed when the slurry to be heated contains 150 parts by mass or more of water per 100 parts by mass of the raw starches. The reason for this is that if the water content of the slurry after the slurry heat treatment (e.g., the slurry to be subjected to the subsequent slurry drying step) is so small that it is less than 150 parts by mass per 100 parts by mass of the raw starches, the gelatinization of the starch in the raw starches may be suppressed during the slurry heat treatment, and the desired effect of the present invention may not be achieved.

[0038] As described above, one example of a method for completing the slurry heating treatment when the slurry to be heated contains 150 parts by mass or more of water per 100 parts by mass of raw starch is a method in which the slurry is heated in a pressurized atmosphere, i.e., under an atmospheric pressure of more than 1 atmosphere. In this case, the container for containing the slurry is preferably pressure-resistant. The pressure of the pressurized atmosphere is not particularly limited and can be adjusted appropriately depending on the amount of solvent contained in the slurry and the heating temperature (product temperature of the slurry). Since the upper temperature limit of the slurry during heating depends on the pressure, it is preferable to set the pressure corresponding to the desired heating temperature. Another example of a method for completing the slurry heating treatment when the slurry contains 150 parts by mass or more of water per 100 parts by mass of raw starch is to use an in-line heating device and blow a gas such as steam into the slurry when heating under normal pressure.

[0039] Next, it is preferable to dry the slurry after heating. In this drying step, the slurry heated in the heat treatment is dried to obtain a solid material containing pregelatinized starches. The method for drying the slurry is not particularly limited, and known drying methods can be used, such as freeze drying, spray drying using a spray dryer or the like, and heat drying using a drum dryer. The degree of drying of the slurry is not particularly limited, but typically, the slurry is dried until the water content of the solid material obtained by drying it is approximately the same as the water content of the raw starches used in the slurry preparation process, more specifically, until it is approximately 15% by mass.

[0040] The solid matter of the slurry obtained through the slurry drying step may be used as a pregelatinized starch as it is, or may be pulverized into powder. The pulverization of the solid matter can be carried out in a conventional manner using a household pulverizer such as a coffee mill or a juicer, or an industrial pulverizer such as a hammer mill, a pin mill, or a jet mill, and the solid matter may be pulverized to the desired particle size.

[0041] Pregelatinized starches produced by the production method of the present invention (hereinafter also referred to as "specific pregelatinized starches") can be used in place of known pregelatinized flours or pregelatinized starches, and can typically be used in the food industry to produce processed foods. The processed foods referred to here are those produced using starches as a raw material, and examples include noodles such as udon, somen, hiyamugi, Chinese noodles, pasta, and instant noodles (including non-fried noodles); bakery foods; fried foods such as tempura, fried chicken, tatsuta-age, and fritters; and powdered foods such as instant soups. Processed foods may also be frozen foods. The pregelatinized starches obtained by the production method of the present invention are particularly suitable for bakery foods, and can provide bakery foods with an excellent moistness and texture, and can also be imparted with aging resistance. Processed foods can be produced according to conventional methods depending on the type of processed food.

[0042] Next, a composition containing the pregelatinized starch of the present invention will be described. Examples of the composition of the present invention include those containing starches including the pregelatinized starches of the present invention, with those containing the pregelatinized starches and non-pregelatinized starches of the present invention being preferred, and those containing the pregelatinized starches and non-pregelatinized cereal flour of the present invention being particularly preferred. Examples of such compositions include dough mixes. Examples of components used in the composition of the present invention, which is a dough mix, include leavening agents or yeast such as sodium bicarbonate (baking soda), baking powder, ammonium carbonate, ammonium bicarbonate, and ammonium chloride; oils and fats such as salad oil; sugars such as sugar; eggs such as whole eggs, egg whites, and egg yolks; dairy products such as milk, skim milk powder, and butter; salts such as salt; and additives such as emulsifiers, thickeners, acidulants, flavorings, spices, colorings, fruit juices, and vitamins, and these can be used alone or in combination of two or more.

[0043] The pregelatinized starches and compositions of the present invention can be used to produce heated dough foods. In the present invention, "heated dough foods" refers to foods produced by mixing cereal flour and / or starch with other ingredients to prepare uncooked dough, and then heating the dough, regardless of the method, such as baking, boiling, frying, or steaming. Examples of heated dough foods to which the present invention is suitably applied include bakery foods, takoyaki, and okonomiyaki. In the present invention, "bakery foods" refers to foods obtained by subjecting batter dough, which is made from cereal flour as the main ingredient and, if necessary, to additional ingredients such as yeast or a leavening agent (e.g., baking powder), water, salt, and sugar, to a heat treatment such as baking, steaming, or frying.

[0044] Bakery foods to which the present invention can be applied include breads; pizzas; cakes; Western-style baked goods such as waffles, choux pastries, biscuits, cookies, and crepes; Japanese sweets including taiyaki, imagawayaki, dorayaki, and ningyoyaki; oily sweets including cake donuts and ponde rings; and flour-based products including okonomiyaki and takoyaki. Examples of breads include white bread, rolls, white bread, brown bread, French bread, hardtack, buns, croissants, tortillas, cooked bread, sweet buns, and steamed bread. Examples of cakes include sponge cakes, butter cakes, rolls, hotcakes, bouche, baumkuchen, pound cakes, cheesecakes, snack cakes, muffins, bars, and pancakes. The bakery food of the present invention may be a bakery food obtained without fermentation with yeast, i.e., a bakery food obtained by heat-treating a non-yeast-fermented dough, or a bakery food obtained by fermentation with yeast, i.e., a bakery food obtained by heat-treating a yeast-fermented dough. Specific examples of bakery foods suitable for the present invention in that they can particularly take advantage of the effects of the particularly moist texture and aging resistance include cakes (especially muffins, hotcakes, steamed cakes, pancakes, roll cakes, etc.); Japanese confectioneries; oil-based confectioneries; and flour-based products.

[0045] The pregelatinized starches of the present invention can also be used in fields other than the food industry. Examples of uses of pregelatinized starches produced using potato starch in fields other than the food industry include caking of feed, caking of foundry sand molds, incense sticks, grinding stones, etc., household laundry glue, and paper strength agents.

[0046] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples. In the following examples, the slurry was freeze-dried, but similar results were obtained when a solid was obtained by heat-drying it using a drum dryer (D-0303 double drum type, manufactured by Katsuragi Kogyo Co., Ltd.).

[0047] Examples 1 to 18, Comparative Examples 1 to 5 Waxy cornstarch was used as a raw material, and water was added in the ratio shown in Table 2 to prepare an aqueous slurry (slurry preparation process). This slurry was gelatinized in a water bath at 100°C (except for Example 13 and Comparative Examples 3 and 5) while stirring, and then further heated at the heating temperature shown in Table 2 for the heating time indicated below. Table 2 also shows the heating time from when the target temperature was reached. In Example 13, gelatinization was performed in a water bath at 90°C, and in Comparative Examples 3 and 5, gelatinization was performed in a water bath at 80°C. Heating time: 30 minutes for Examples 1 to 14 and Comparative Examples 1 to 5. The heating time for Examples 15 to 18 is shown in Table 2. When the heating temperature was 100°C or less, heating was performed in a water bath, and when the heating temperature was higher than 100°C, heating was performed in an autoclave or a cooker static mixer (manufactured by Noritake Co., Ltd.). The slurry (gelatinized liquid) that had undergone the slurry heat treatment was freeze-dried using a commercially available freeze dryer (product name "Virtis Wizard 2.0 Lyophilizer Controller", manufactured by SP INDUSTRES, INC.) to obtain a solid (slurry drying step). The obtained solid was pulverized using an ultracentrifugal grinder to produce a pregelatinized starch. The gelation degree and progression distance of the obtained pregelatinized starch were measured using the methods described above. The gelation degree was measured in six replicates, and the progression distance was measured in four replicates. "Nisshoku Waxy Starch IPY" manufactured by Nippon Shokuhin Kako Co., Ltd. was used as the waxy cornstarch.

[0048] Using the obtained pregelatinized starch, bakery foods were produced according to the formulation shown in Table 1 below and the following procedure.

[0049] <Bakery Food Manufacturing Procedure> Salad oil, eggs, milk, and water were added to a container and mixed. Then, weak flour, pregelatinized starch, and a leavening agent were added and mixed by hand whisking for 60 seconds (120 rpm). After a 10-minute floor time, 50 g of batter was placed in a frying pan and baked at 180°C for 3 minutes on the front side, then flipped and baked for 3 minutes on the back side to obtain four hotcakes. Nisshin Flour Milling Co., Ltd.'s "Flour" was used as the weak flour. Oriental Yeast Co., Ltd.'s "Baking Powder Meister All" was used as the leavening agent.

[0050] <Formulation>

[0051] The resulting hot cakes were stored at 4°C for 3 days, and then evaluated for moistness and melt-in-the-mouth texture according to the following criteria. The evaluation was carried out by eight expert panelists. The average scores are shown in Table 2 below. The test involved tasting chilled hot cakes to make it easier to sense the staleness.

[0052] <Evaluation criteria for moist feeling> 5 points: Quite moist, very good. 4 points: Moist, good. 3 points: Slightly moist, good. 2 points: Not moist, slightly poor. 1 point: Not moist at all, poor.

[0053] <Evaluation criteria for melt-in-the-mouth feel> 5 points: Melts very well in the mouth, very good. 4 points: Melts well in the mouth, good. 3 points: Melts somewhat well in the mouth, good. 2 points: Feels slightly sticky, does not melt easily in the mouth. 1 point: Feels sticky, does not melt easily in the mouth.

[0054]

[0055] As shown in Table 2, it can be seen that the moistness and melt-in-the-mouth texture of bakery products are improved by using a pregelatinized starch having a gelation degree of 13.0 or more and a progress distance of 3.30 cm or less.

[0056] According to the present invention, it is possible to provide pregelatinized starches that can impart excellent aging resistance and an excellent moist texture when used in foods.

Claims

1. Pregelatinized starches having a degree of gelation of 13.0 or more and a travel distance of 3.30 cm or less, where the degree of gelation is the ratio Wf / Ws of the amount of gel produced when the pregelatinized starch is mixed with 100 times the mass of water, Wf, to the amount of pregelatinized starch before mixing, Ws, and the travel distance is the distance traveled by 10 g of a gel obtained by mixing water and pregelatinized starch so that the water content of the resulting gel is 90.9 mass%.

2. A method for producing pregelatinized starches according to claim 1, comprising a step of adding water to and heating raw starch, wherein the amount of water added in said step is 150 parts by mass or more per 100 parts by mass of the raw starch, and the heating temperature is 90°C or higher and 165°C or lower.

3. The method for producing pregelatinized starches according to claim 2, wherein the amount of water added in the step is 1,500 parts by mass or less per 100 parts by mass of the raw starch.

4. The method for producing pregelatinized starches according to claim 2, wherein the average particle size of the raw starches is 5.0 μm or more and 250 μm or less.

5. The method for producing pregelatinized starches according to claim 2, wherein starches having an amylose content of less than 5% are used as the raw starches.

6. The method for producing pregelatinized starches according to claim 5, wherein waxy corn starch is used as the starch having an amylose content of less than 5%.

7. The method for producing pregelatinized starches according to claim 2, wherein the raw starch is a pregelatinized starch that has not been chemically modified.

8. A composition containing the pregelatinized starch according to claim 1 or the pregelatinized starch produced by the production method according to any one of claims 2 to 7.

9. A heated dough food product using the pregelatinized starch according to claim 1 or the pregelatinized starch produced by the production method according to any one of claims 2 to 7.

10. The heated dough food product according to claim 9, which is a bakery food product obtained by heating a batter containing the pregelatinized starch.