Production method for oil-or-fat-coated resistant starch

Abstract

The present invention addresses the problem of providing, using a simple method, a resistant starch which improves the grainy texture which is a characteristic problem of foods containing a resistant starch, and, when used in a food with the aim of carbohydrate reduction or dietary fiber enrichment, does not degrade a pleasant smooth texture inherent to the food. The present invention is a production method for an oil-or-fat-coated resistant starch in which an oil or fat is adhered to the surface of a resistant starch, said method comprising a mixing step for mixing 100 parts by mass of the resistant starch and 0.5-5 parts by mass of the oil or fat. By means of the mixing step, the average particle size of the resistant starch after mixing is set to be 1.0-1.2 times the average particle size of the resistant starch before mixing.

Description

Method for producing fat-coated resistant starch

[0001] The present invention relates to a technology for improving resistant starch.

[0002] Carbohydrates are one of the three major nutrients, along with lipids and proteins. However, consuming large amounts of carbohydrates can contribute to an increase in body fat, and if consuming large amounts of carbohydrates raises blood sugar levels, it can become a risk factor for diabetes. For these reasons, there has been a growing demand for low-carbohydrate foods in recent years.

[0003] Dough foods, such as bakery foods and noodles, are typically produced using dough, which is a mixture of powder ingredients such as cereal flour and starch with liquid ingredients such as water, as an intermediate product, and contain a large amount of carbohydrates. Therefore, in order to reduce the carbohydrate content of dough foods, the cereal flour (carbohydrate) contained in dough foods has traditionally been replaced with dietary fiber, and examples of such dietary fiber include resistant starch, resistant dextrin, and inulin. However, the inclusion of dietary fiber in dough foods creates a rough texture, which deteriorates the taste and texture of the dough foods, resulting in a loss of palatability as a food. This tendency is particularly pronounced when resistant starch is used.

[0004] Various proposals have been made to provide a resistant starch that, when used in foods, does not impair the original taste or texture of the food. Patent Document 1 describes a coated starch in which a coating material containing oil or fat is attached to the surface of a core material mainly made of resistant starch, and the amount of oil or fat attached to the core material is 5 to 25 parts by mass per 100 parts by mass of the core material. Patent Document 1 states that the coated starch improves the rough texture that is a problem specific to foods containing resistant starch, and can impart a smooth texture that is pleasant to the tongue to the food.

[0005] Patent Document 2 describes a resistant oil-treated starch having a viscosity of 50 mPa·s or more after 10 seconds when a 40% by mass starch suspension is measured at 30°C using a rotational viscometer at a rotation speed of 60 rpm, and describes a production method thereof in which 0.02 to 5.0% by mass of oil is mixed with the resistant starch and heat-treated until the viscosity of the 40% by mass starch suspension reaches 50 mPa·s or more. Patent Document 2 also describes that the resistant oil-treated starch has the effects of enriching dietary fiber and reducing carbohydrate content, and can also exhibit other functions desired in foods, such as improving texture. Patent Document 3 describes a coating material for deep-fried foods, characterized by containing an oil-treated flour obtained by adding edible oils and fats containing 15% by mass or more of trivalent or higher unsaturated fatty acids in total to starch and / or grain flour, mixing the mixture uniformly, and then subjecting the mixture to a heat-aging treatment. Patent Document 3 describes that when the coating material for deep-fried foods is used, a coating that does not peel or blister and has an excellent texture that is soft and not sticky can be obtained.

[0006] JP 2022-139073 A JP 2021-016379 A JP 2004-113236 A

[0007] An object of the present invention is to provide, by a simple method, a resistant starch that improves the rough texture that is a problem specific to foods containing resistant starch, and that does not impair the inherent smooth texture that is pleasant to the tongue of the food when used in foods for the purpose of reducing sugar content or enriching dietary fiber.

[0008] The present invention is a method for producing an oil-coated resistant starch in which an oil or fat is attached to the surface of the resistant starch, the method comprising a mixing step of mixing 100 parts by mass of the resistant starch with 0.5 to 5 parts by mass of an oil or fat, and the mixing step makes the average particle size of the resistant starch after the mixing 1.0 to 1.2 times the average particle size of the resistant starch before the mixing.

[0009] The production method of the present invention produces an oil-coated resistant starch in which an oil or fat is attached to the surface of the resistant starch, and uses at least a resistant starch and an oil or fat as raw materials. The oil-coated resistant starch obtained by the production method of the present invention (hereinafter also referred to as "the oil-coated resistant starch of the present invention") is low in carbohydrates and calories because it is mainly made of resistant starch, and furthermore, the rough texture that is a problem specific to resistant starch is eliminated by coating with an oil or fat.

[0010] The oil-coated resistant starch according to the present invention comprises resistant starch and an oil or fat adhered to the surface of the resistant starch. That is, the oil-coated resistant starch according to the present invention is an aggregate of resistant starch particles, and an oil or fat is adhered to the surface of the resistant starch particles. There are no particular restrictions on the state of oil or fat adhered to the surface of the resistant starch particles, and the oil or fat typically forms a lamellar oil or fat coating layer. In the oil-coated resistant starch according to the present invention, when focusing on one particle, the oil or fat may be adhered to the entire surface of the particle, or may be adhered to only a part of the particle surface. Furthermore, in the oil-coated resistant starch according to the present invention, it is sufficient that the oil or fat is adhered to at least some of the particles, and it is not necessarily required that the oil or fat is adhered to all of the particles.

[0011] In the manufacturing method of the present invention, resistant starch is used as a main raw material. Resistant starch is a starch that is resistant to digestion by digestive enzymes and is a type of dietary fiber. As used herein, "dietary fiber" refers to a food ingredient that is not digested by human digestive enzymes. Starch is a polymer in which glucose is bonded in large numbers via α(1,4) and α(1,6) bonds, and biologically derived starch is generally degraded by digestive enzymes. However, even if it is biologically derived, starch that has a specific structure in part or entirely, or starch that has been chemically modified, becomes resistant to digestive enzymes.

[0012] Resistant starches are generally classified into four types, RS1 to RS4, as follows. RS1 is a type of resistant starch that is easily digestible but physically protected by an outer skin or other barrier, making it resistant to digestion by digestive enzymes. It is mainly found in whole grains, seeds, legumes, etc. RS2 is a type of resistant starch that is resistant to digestion due to the special crystalline structure of the starch granules. Examples of RS2 include potato starch that has been subjected to moist heat treatment under low moisture conditions and unripe banana starch. High-amylose starch, which contains a large amount of linear amylose, is also classified as RS2. RS3 is a type of resistant starch that is resistant to digestion due to a change in structure caused by starch retrogradation that makes it less susceptible to digestive enzymes. Examples of RS3 include retrograded starch (beta-starch) obtained by first gelatinizing (gelatinizing) the starch by heating and then cooling it. RS4 is a resistant starch that is highly chemically modified and therefore resistant to digestion, and examples of RS4 include cross-linked starch that has been subjected to a strong cross-linking treatment, and etherified and / or esterified starch.

[0013] The resistant starch used in the present invention may be natural starch (unprocessed starch) or processed starch. Furthermore, the source of the resistant starch is not particularly limited, and it may be derived from any plant, such as tapioca starch or potato starch. In the present invention, the resistant starch may be one selected from the above-mentioned RS1 to RS4, or two or more may be used in combination.

[0014] As can be seen from the above descriptions of RS1 to RS4, resistant starch may contain impurities (substances that cannot be completely removed during the purification of resistant starch). From the perspective of ensuring low-sugar foods and dietary fiber enrichment, the resistant starch used in the present invention preferably has few impurities, i.e., high purity. More specifically, the resistant starch used in the present invention preferably has a dietary fiber content of 75% by mass or more, calculated on a starch dry matter basis. The above-mentioned RS4, particularly phosphate-crosslinked starch, is preferred because its dietary fiber content is increased by chemical modification (such as phosphate crosslinking) under appropriate conditions. Many RS4, particularly phosphate-crosslinked starch, have a dietary fiber content of 75% by mass or more, calculated on a starch dry matter basis. The term "phosphate-crosslinked starch" as used herein refers to processed starch that has been subjected to at least phosphate crosslinking treatment; it may also be subjected to processing other than phosphate crosslinking (e.g., pregelatinization). Note that the term "dietary fiber content" used herein refers to a value determined in accordance with AOAC 2011.25. For example, the dietary fiber content can be measured using a commercially available measurement kit, such as a dietary fiber measurement kit (Wako Pure Chemical Industries, Ltd.).

[0015] In the present invention, commercially available products can be used as the raw material resistant starch. For example, commercially available examples of RS2 products include Nisshoku Roadster (manufactured by Nippon Shokuhin Kako Co., Ltd.), Himaizu 1043 (manufactured by Nippon NSC Co., Ltd.), and Actistar 11700 (manufactured by Cargill Japan Co., Ltd.). Commercially available examples of RS4 products include Pine Starch RT (manufactured by Matsutani Chemical Industry Co., Ltd.), Novelose (manufactured by Ingredion Inc.), Fibergym RW (manufactured by Matsutani Chemical Industry Co., Ltd.), and Actistar RT 75330 (manufactured by Cargill Japan Co., Ltd.).

[0016] Furthermore, the form of the resistant starch is not particularly limited, and may be what is generally referred to as powder, fine grains, granules, etc. Furthermore, the particle size of the resistant starch is not particularly limited, and may be appropriately selected depending on the intended use of the resulting oil-coated resistant starch, etc. For example, from the viewpoint of the balance between the handleability of the oil-coated resistant starch and the texture of foods using the oil-coated resistant starch, the average particle size of the resistant starch used as a raw material is preferably 5 to 30 μm, more preferably 15 to 25 μm.

[0017] In this specification, the "average particle size" refers to the particle size at which the cumulative amount, starting from the smallest particle, accounts for 50% of the total volume on a cumulative particle size distribution curve of the resistant starch (or fat-coated resistant starch) measured by a dry laser diffraction / scattering method. The average particle size can be measured in accordance with a standard method using, for example, a commercially available laser diffraction particle size distribution analyzer (e.g., Microtrac MT3300EXII, manufactured by Nikkiso Co., Ltd.).

[0018] In the present invention, in addition to the resistant starch, an oil or fat is used as a raw material. The type of oil or fat is not particularly limited, as long as it is usable in foods and can be mixed with the resistant starch. For example, it may be a solid oil or fat that is solid at room temperature and normal pressure, or a liquid oil or fat that is liquid at room temperature and normal pressure, or it may be a vegetable oil or animal oil or fat. Examples of oils and fats include rapeseed oil, soybean oil, sesame oil, safflower oil, olive oil, cottonseed oil, corn oil, rice oil, palm oil, sunflower oil, safflower oil, beef tallow, lard, fish oil, hydrogenated oils and fats, and mixed oils and fats thereof. In the present invention, one type of these oils and fats may be used alone, or two or more types may be used in combination.

[0019] An example of a preferred oil or fat in the present invention is an oil or fat having an elevation melting point of 5°C or less, more preferably an elevation melting point of 0°C or less, and even more preferably an elevation melting point of -5°C or less. By using such an oil or fat, the mixing step described below can be carried out successfully. Specific examples of oils or fats having an elevation melting point of 5°C or less include rapeseed oil, soybean oil, and rice bran oil. The lower the elevation melting point of the oil or fat, the more preferable, and there is no particular lower limit, but the elevation melting point of the oil or fat is usually at most about -20°C. In this specification, "elevation melting point" means the melting point of the oil or fat measured in accordance with Standard Methods for Analysis of Fats, Oils, and Related Materials 2.2.4.2-1996.

[0020] In the method for producing an oil-coated resistant starch of the present invention, 100 parts by mass of the resistant starch is mixed with 0.5 to 5 parts by mass of the oil (mixing step). That is, the amount of oil used in the mixing step (the amount added when oil is added to the resistant starch) is 0.5 to 5 parts by mass per 100 parts by mass of the resistant starch. If the amount of oil used is less than 0.5 parts by mass or more than 5 parts by mass, the effect of improving the rough texture caused by the resistant starch in foods containing the resistant starch is poor. The amount of oil used is preferably 1.5 to 3.5 parts by mass.

[0021] By mixing the resistant starch with the oil or fat, the oil or fat adheres to the surface of the resistant starch. In the present invention, the average particle size of the resistant starch after mixing (i.e., the oil-coated resistant starch) is set to 1.0 to 1.2 times the average particle size of the resistant starch before mixing. Hereinafter, the "ratio of the average particle size of the resistant starch after mixing to the average particle size of the resistant starch before mixing" is also referred to as the "average particle size increase ratio." Thus, the present invention is characterized in that a small amount of oil or fat is adhered to the resistant starch such that the average particle size increase ratio of the resistant starch is about 1.0, i.e., such that the average particle size of the resistant starch remains almost unchanged before and after mixing with the oil or fat. In other words, the oil-coated resistant starch of the present invention is characterized in that the amount of oil or fat adhered to the resistant starch is relatively small, in other words, the thickness of the oil or fat coating layer is relatively thin. Due to these characteristics, the oil-coated resistant starch of the present invention solves the problems associated with conventional resistant starches and, when used in foods, has the effect of not impairing the inherently pleasant, smooth texture of the food. From the viewpoint of ensuring this effect, the average particle size increase ratio is preferably 1.0 to 1.1 times. If the average particle size increase ratio exceeds 1.2 times, the effect of improving the rough texture caused by resistant starch in foods containing resistant starch is poor. The average particle size increase ratio can be adjusted by appropriately adjusting the amount of oil or fat used, the method of mixing the resistant starch with the oil or fat, etc.

[0022] In the mixing step, the method for mixing the raw materials, resistant starch and fat / oil, is not particularly limited, as long as the two components are mixed together and the average particle size increase ratio is 1.0 to 1.2 times. "Mixing" in the present invention includes aspects that involve only the operation of bringing the two into contact, such as by adding fat / oil to the resistant starch, and aspects that involve the operation of stirring the two during or after contacting them, but is typically the latter, and specifically involves, for example, "addition and stirring." Mixing with stirring can be carried out using a stirring device such as a variety of mixers.

[0023] For example, in the production of the resistant starch treated with oils and fats described in Patent Documents 2 and 3, oils and fats are added to the resistant starch as a raw material, and then the mixture is heated and / or aged. In contrast, the production method of the present invention does not require such heating or aging. Preferably, in all steps of the production method of the present invention, none of the raw material, the oil-coated resistant starch, or its production intermediates are heated or aged. The absence of heating or aging leads to simple and efficient production.

[0024] The "raw materials" referred to here include at least the resistant starch and the oil or fat, and the "production intermediate" is, for example, a mixture in the middle of a mixing step. The term "heating" used here means "intentional application of heat from the outside" and does not exclude unintentional heating, such as an increase in the ambient temperature during storage of raw materials in summer. Furthermore, the term "aging" used here means "intentional leaving" and does not exclude unintentional leaving, such as storage of raw materials or storage of the oil-coated resistant starch according to the present invention after its production until its use. In other words, the oil-coated resistant starch according to the present invention achieves the intended effect even immediately after its production (i.e., without intentional leaving). The heating and aging of raw materials and the like are restricted here to "all steps in the production method of the present invention," i.e., steps from the time when raw materials are used to obtain the target oil-coated resistant starch to the time when the oil-coated resistant starch is obtained, and steps other than these steps are not subject to such restrictions. The above phrase "in all steps of the production method of the present invention" is not intended to exclude the possibility that the resistant starch and fats and oils themselves as raw materials may be subjected to heating and / or aging during their production.

[0025] The resistant starch and the oil / fat are preferably mixed by stirring, and the stirring time is preferably 7.5 minutes or longer. A stirring time of 7.5 minutes or longer makes it possible to easily achieve an average particle size increase ratio of 1.0 to 1.2 times. A longer stirring time more reliably achieves an average particle size increase ratio of 1.0 to 1.2 times, but excessively long stirring times make the production method inefficient. In light of this, a stirring time of at most 45 minutes is desirable. Typically, the oil / fat is added to the resistant starch during stirring. However, the entire amount of the oil / fat to be used may be added to the resistant starch before stirring begins. Alternatively, a portion of the oil / fat to be used may be added to the resistant starch before stirring begins, and the remainder of the oil / fat may be added after stirring begins, followed by further stirring. The stirring time begins when stirring is initiated while the resistant starch and at least a portion of the oil / fat are in contact with each other, and ends when stirring is stopped. As will be described later, the present invention also includes cases in which the stirring treatment of the resistant starch and the oil or fat is carried out multiple times, i.e., cases in which treatment other than stirring is performed between the preceding stirring treatment and the subsequent stirring treatment. In such cases, the stirring time is the sum of the stirring times for each of the multiple stirring treatments. For example, the below-described Embodiment 1 includes a treatment of mixing the resistant starch and the oil or fat by stirring (first stirring treatment), a treatment of passing the mixture through a sieve (treatment other than stirring), and a treatment of stirring the undersize fraction (second stirring treatment). The stirring time in Embodiment 1 is the sum of the time required for the first stirring treatment and the time required for the second stirring treatment (stirring time for the undersize fraction). The rotation speed of the stirrer used for stirring can be, for example, 25 to 600 rpm, although it depends on the stirring time and the amount of raw material used.

[0026] In a preferred embodiment of the production method of the present invention, the mixing step includes mixing the resistant starch and the oil / fat by stirring (preferably, adding the oil / fat to the resistant starch and stirring the mixture), passing the mixture through a sieve, and stirring the fraction that passed through the sieve (the under-sieve fraction) (hereinafter also referred to as Embodiment 1). According to Embodiment 1, the average particle size increase ratio of 1.0 to 1.2 can be achieved without requiring a long stirring time, and the intended effect, i.e., the effect of improving the rough texture caused by the resistant starch in foods containing the resistant starch, can be further enhanced. The stirring time for the resistant starch and the oil / fat before passing through the sieve is preferably 2.5 minutes or more, and the stirring time for the under-sieve fraction is preferably 5 minutes or more. Furthermore, the combined stirring time for both preferably satisfies the above-mentioned preferred stirring time of 7.5 minutes or more. In Embodiment 1, by passing the mixture through a sieve during the production process, the aforementioned average particle size increase ratio of 1.0 to 1.2 can be achieved even with a short stirring time. More specifically, the stirring time of the resistant starch and the oil or fat before passing through the sieve can be 7.5 minutes or less, and the stirring time of the undersize fraction can be 12.5 minutes or less. Furthermore, even if the total stirring time of both is 20 minutes or less, it is possible to satisfy the average particle size increase factor of 1.0 to 1.2 times. The mesh size of the sieve is preferably 0.5 to 2 mm, although it depends on the average particle size of the resistant starch used as a raw material.

[0027] In another preferred embodiment of the production method of the present invention, the mixing step includes mixing the resistant starch and the oil / fat by stirring, and the stirring time is 10 minutes or more (hereinafter also referred to as Embodiment 2). More specifically, in Embodiment 2, stirring is performed for 10 minutes or more, more preferably 15 minutes or more, while the resistant starch and at least a portion of the oil / fat are in contact with each other, without performing a sieving operation. According to Embodiment 2, although the stirring time generally tends to be longer than in Embodiment 1, it is possible to achieve the intended effect, i.e., the effect of improving the rough texture caused by resistant starch in foods containing resistant starch, with a simple method that does not involve heating or aging or a sieving operation.

[0028] The average particle size of the resistant starch (oil-coated resistant starch) after mixing (after the mixing step) is not particularly limited, but is preferably 5 to 30 μm, more preferably 15 to 25 μm, provided that the average particle size increase ratio is 1.0 to 1.2 times, depending on factors such as the average particle size of the resistant starch before mixing.

[0029] As described above, in the oil-coated resistant starch according to the present invention, the oil typically forms a laminar oil-coating layer. The oil-coating layer is primarily composed of the aforementioned oil, and the content of the oil in the oil-coating layer is 100% by mass or nearly so, based on the total mass of the oil-coating layer. The oil-coating layer may contain components other than the oil, as long as the desired effects of the present invention are achieved. Examples of such components include emulsifiers such as shellac, wax, monoglycerin fatty acid esters, sucrose fatty acid esters, and polyglycerin fatty acid esters; metal salts of fatty acids such as calcium stearate and magnesium stearate; sweeteners such as sucralose and thaumatin; and flavors. These components may be used alone or in combination of two or more. When these other components are used, they may also be mixed with the resistant starch and the oil. Furthermore, when other components are used, the total amount used is desirably 10% by mass or less relative to the total mass of the oil-and-fat coating layer (i.e., the total amount of the oil and the other components) in order to reliably achieve the effects intended by the present invention.

[0030] The oil-coated resistant starch obtained by the production method of the present invention can be used in various foods, and is particularly useful as an ingredient for reducing the sugar content of dough foods. As used herein, "dough food" refers to a food produced by forming an intermediate product, which is a mixture of powder ingredients such as cereal flour or starch and liquid ingredients such as water, into a predetermined shape and then heating it. "Dough" here encompasses clay-like dough (so-called dough) and liquid or paste-like dough (so-called batter). Specific examples of dough foods include bakery foods, noodles, and battered fried foods.

[0031] As used herein, "bakery food" refers to foods obtained by adding liquid ingredients such as water to cereal flour (grain flour, starch) as the main ingredient, and optionally adding auxiliary ingredients such as yeast or leavening agents (e.g., baking powder), salt, and sugar to obtain a fermented or unfermented dough, which is then subjected to heat treatments such as baking, steaming, and deep-frying. Specific examples of bakery foods include breads; pizzas; cakes; Japanese and Western baked goods such as waffles, choux pastries, biscuits, dorayaki, and baked buns; steamed sweets; fried sweets such as donuts and corn dogs; and snacks such as okonomiyaki, takoyaki, chijimi, and negiyaki. Specific examples of cakes include sponge cake, butter cake, roll cake, hotcake, bouche, baumkuchen, pound cake, cheesecake, snack cake, muffin, bar, cookie, crepe, and pancake.

[0032] As used herein, "noodles" refers to foods made by kneading a dough made primarily from cereal flour (cereal flour, starch), to which a liquid ingredient such as water has been added, and optionally with secondary ingredients such as salt, and then 1) rolling or stretching the dough to obtain a noodle sheet dough, which is then stretched, cut, punched, or the like, or 2) extrusion-molded into a predetermined shape such as noodle strands. Specific examples of noodles include soba, udon, hiyamugi, Chinese noodles, spaghetti, macaroni, ravioli, and noodle skins.

[0033] In this specification, "battered fried foods" refers to foods obtained by adding a liquid ingredient such as water to a cereal flour (grain flour, starch) as the main ingredient, and optionally adding auxiliary ingredients such as a leavening agent (baking powder, etc.), salt, sugar, soy sauce, garlic, etc. to obtain a liquid batter, which is then applied to the surface of ingredients and subjected to a heat treatment such as frying or baking. Specific examples of battered fried foods include tempura, fried chicken, tatsuta-age, and fritters.

[0034] The oil-coated resistant starch according to the present invention can be used in the same manner as various dough ingredients blended into dough foods. For example, in the production of dough foods using batter, such as cakes and fried foods with coating, the oil-coated resistant starch according to the present invention may be blended in at the early stage of dough preparation, or may be blended into dough after preparing the dough using other powder ingredients and liquid ingredients. For example, in the production of bread by the straight method or dough foods using dough, such as noodles and cookies, the oil-coated resistant starch according to the present invention is preferably blended in at the early stage of dough preparation (for example, before the addition of liquid ingredients) in the same manner as the first dough ingredient, such as wheat flour. For example, in the production of bread by the sponge dough method, the oil-coated resistant starch according to the present invention may be blended as a sponge dough blending ingredient before the sponge dough fermentation, or may be blended into the main kneading ingredients.

[0035] Furthermore, the oil-coated resistant starch according to the present invention may be incorporated into a mix for dough foods (hereinafter also simply referred to as a "mix"). The content of the oil-coated resistant starch according to the present invention in the mix is ​​not particularly limited and may be adjusted appropriately depending on the intended use of the mix, but for example, when the dough food produced using the mix is ​​the aforementioned bakery food, noodles, or battered fried food, the content is preferably 5 to 40% by mass, and more preferably 10 to 30% by mass, relative to the total mass of the mix, from the viewpoint of balancing the effects of the oil-coated resistant starch (such as reducing the sugar content of the dough food) with the taste and texture of the dough food.

[0036] The mix typically contains one or more types of cereal flour other than the oil-coated resistant starch of the present invention. In this specification, "cereal flour" refers to a cereal-derived substance that is powdery at room temperature and normal pressure, and is a concept that includes cereal flour and starch. Unless otherwise specified, "starch" refers to "pure starch" isolated from plants such as wheat, and is distinguished from starch inherent in cereal flour. Examples of cereal flour include wheat flour (strong flour, semi-strong flour, medium-strength flour, weak flour, durum wheat flour, whole wheat flour, etc.), buckwheat flour, rice flour, corn flour, barley flour, rye flour, adlay flour, barnyard millet flour, and foxtail millet flour. Examples of starch include starches (raw starches) such as tapioca starch, potato starch, cornstarch, waxy cornstarch, wheat starch, and rice starch; and processed starches obtained by subjecting raw starches to one or more of the following treatments: gelatinization, etherification, esterification, acetylation, cross-linking, and oxidation. The coated starch mentioned above is a type of modified starch.

[0037] The total content of cereal flours, including the oil-coated resistant starch according to the present invention, in the mix is ​​not particularly limited and may be adjusted appropriately depending on the intended use of the mix, etc.; for example, when the dough food to be produced using the mix is ​​the aforementioned bakery food, noodle, or battered fried food, the total content is preferably 5 to 90% by mass, and more preferably 10 to 80% by mass, relative to the total mass of the mix.

[0038] In addition to the flour, the mix may contain other ingredients as needed, such as emulsifiers such as glycerin fatty acid esters, sucrose fatty acid esters, sorbitan fatty acid esters, propylene glycol fatty acid esters, lecithin, organic acid monoglycerides, sodium stearoyl lactylate, and calcium stearoyl lactylate; protein materials such as gluten, gliadin, and glutenin (all wheat proteins), skim milk powder, whey protein (all milk proteins), soy protein, and gelatin; fats and oils such as animal fats and vegetable oils; salt, powdered soy sauce, fermented products such as fruit-derived fermented products, powdered miso paste, amino acids, and other seasonings; dried eggs such as egg powder; sugars, sweeteners; thickening polysaccharides, leavening agents, dairy ingredients, flavorings, enzymes, and colorings. The content of other ingredients in the mix other than the flour may be adjusted appropriately depending on the intended use of the mix.

[0039] The mix can be used as a powder ingredient when producing dough foods. For example, a method for producing bakery foods or noodles using the mix typically includes the steps of adding a liquid ingredient to the mix to prepare a dough (specifically, for example, dough or batter), shaping the dough into a predetermined shape, and then heating the shaped dough (specifically, for example, baking, steaming, frying, or steaming). A method for producing a battered fried food using the mix typically includes the steps of adding a liquid ingredient to the mix to prepare a dough (specifically, for example, batter), adhering the dough to the surface of ingredients, and then placing the ingredients with the batter in heated oil for frying. The liquid ingredient added to the mix can be water, oil, seasoning liquid, egg liquid, milk, or the like, and can be selected appropriately depending on the type of dough food to be produced. The mixing ratio of the mix to the liquid ingredient is not particularly limited, but is generally about 50 to 300 parts by mass per 100 parts by mass of the mix.

[0040] The aspects of the present invention are, for example, as follows. <1> A method for producing an oil-coated resistant starch having an oil or fat attached to the surface of the resistant starch, comprising a mixing step of mixing 100 parts by mass of the resistant starch with 0.5 to 5 parts by mass of an oil or fat, wherein the mixing step causes the average particle size of the resistant starch after the mixing to be 1.0 to 1.2 times the average particle size of the resistant starch before the mixing. <2> The method according to <1>, wherein the mixing of the resistant starch and the oil or fat in the mixing step is carried out by stirring, and the stirring time is 7.5 minutes or longer. <3> The method according to <1> or <2>, wherein the mixing step comprises mixing the resistant starch and the oil or fat by stirring, passing the mixture through a sieve, and stirring the fraction that passed through the sieve. <4> The method according to any one of <1> to <3>, wherein the oil or fat has an ascending melting point of 5°C or lower. <5> The production method according to any one of <1> to <4> above, wherein the oil or fat is one or more selected from the group consisting of rapeseed oil, soybean oil, and rice bran oil. <6> The production method according to any one of <1> to <5> above, wherein the resistant starch is a processed starch that has been at least phosphate cross-linked. <7> The production method according to any one of <1> to <6> above, wherein the dietary fiber content of the resistant starch is 75% by mass or more calculated on a starch dry matter basis. <8> The production method according to any one of <1> to <7> above, wherein none of the raw materials, the oil-coated resistant starch, or its production intermediates are heated or aged in any of the steps of the production method.

[0041] 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, "%" is by mass unless otherwise specified.

[0042] Examples 1 to 4, Comparative Examples 1 to 3 Oil-coated resistant starch was produced by mixing 100 g of resistant starch as raw material with the amount of rapeseed oil listed in Table 1 using a vertical mixer (manufactured by Hobart Co., Ltd., product name "HL-200") as a mixer. Specifically, the resistant starch and rapeseed oil were mixed using one of the following mixing methods a, b, or c (see Table 1). In all mixing methods, the mixer was rotated at a speed of 107 rpm. Heating and aging were not performed throughout the production process of the oil-coated resistant starch. Mixing method a: Rapeseed oil was added to the resistant starch and the mixture was stirred for 5 minutes using a mixer. The resulting mixture was then passed through a sieve with 1 mm openings, and the undersieve fraction was stirred for 5 minutes using a mixer. Mixing method b: Rapeseed oil was added to the resistant starch and the mixture was stirred for 30 minutes using a mixer. Mixing method c: Rapeseed oil was added to the resistant starch and mixed with a mixer for 5 minutes.

[0043] Details of the raw materials listed in Table 1 are as follows: Resistant starch: Matsutani Chemical Industry Co., Ltd., product name "Pine Starch RT" (phosphate cross-linked starch derived from tapioca starch, dietary fiber content 95% by mass (starch dry matter equivalent)) Rapeseed oil: Nisshin Oillio Group, Ltd., product name "Nissin Canola Oil" (rise melting point -15.3°C)

[0044] [Test Example] 33.5% of the obtained oil-coated resistant starch, 33.5% of soft flour, 30% of sugar, and 3% of baking powder were mixed to prepare a hotcake mix. 25 g of whole egg liquid and 75 g of milk were added to 100 g of the hotcake mix as liquid ingredients, and the mixture was hand-mixed with a whisk at 120 rpm for 1 minute to prepare a batter. After allowing the batter to stand for 5 minutes at room temperature and normal pressure, the entire batter was poured onto a griddle and baked at 150°C for 3 minutes. The batter was then inverted and baked again at 150°C for another 3 minutes to obtain a hotcake. A hotcake was also prepared as a control example in the same manner as above, except that the resistant starch used as the raw material for the oil-coated resistant starch was used instead of the oil-coated resistant starch. The resulting hotcakes were tasted by 10 expert panelists, who evaluated the texture (less roughness) according to the following criteria. The results are shown in Table 1 as the average scores of the 10 panelists.

[0045] <Evaluation criteria for texture> 5 points: The texture is much less rough than the control. 4 points: The texture is much less rough than the control. 3 points: The texture is roughly the same as the control. 2 points: The texture is much rougher than the control. 1 point: The texture is much rougher than the control.

[0046]

[0047] Examples 5 and 6 Oil-coated resistant starch was obtained in the same manner as in Example 2, except that the oils and fats listed in Table 2 were used instead of rapeseed oil. Hot cakes were made using the obtained oil-coated resistant starch in the same manner as in the above test example, and the texture thereof was evaluated. The results are shown in Table 2. Details of the oils and fats listed in Table 2 are as follows (the resistant starch and rapeseed oil are the same as in Example 2). Soybean oil: Nisshin Soybean White Refined Oil, manufactured by The Nisshin Oillio Group, Ltd. (rise melting point -9.3°C) Rice oil: Nisshin Rice Bran Oil, manufactured by The Nisshin Oillio Group, Ltd. (rise melting point -6.8°C)

[0048]

[0049] According to the present invention, it is possible to produce an oil-coated resistant starch that improves the rough texture that is a particular problem of foods containing resistant starch and that does not impair the food's inherent smooth, pleasant texture when used in foods for the purposes of reducing carbohydrate content or enriching dietary fiber. The oil-coated resistant starch requires only a small amount of oil and fat in its production, and does not require any special heating or aging treatment, so it can be produced easily.

Claims

1. A method for producing an oil-coated resistant starch having an oil attached to the surface of the resistant starch, comprising a mixing step of mixing 100 parts by mass of the resistant starch with 0.5 to 5 parts by mass of an oil, the mixing step making the average particle size of the resistant starch after the mixing 1.0 to 1.2 times the average particle size of the resistant starch before the mixing.

2. The method according to claim 1, wherein the mixing of the resistant starch and the oil in the mixing step is carried out by stirring, and the stirring time is 7.5 minutes or longer.

3. The method of claim 1 or 2, wherein the mixing step comprises mixing the resistant starch and the oil by stirring, passing the mixture through a sieve, and stirring the fraction that passes through the sieve.

4. The method according to claim 1 or 2, wherein the fat or oil has a slip melting point of 5°C or lower.

5. The method according to claim 1 or 2, wherein the oil is one or more selected from the group consisting of rapeseed oil, soybean oil and rice oil.

6. The method according to claim 1 or 2, wherein the resistant starch is a modified starch that has been subjected to at least a phosphate cross-linking treatment.

7. A method for producing a food product according to claim 1 or 2, wherein the dietary fiber content of the resistant starch is 75% by mass or more in terms of dry starch.

8. The method according to claim 1 or 2, wherein the raw materials, the oil-coated resistant starch and its production intermediates are neither heated nor aged in any of the steps of the method.

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