Method for producing modified resistant starch

Abstract

The present invention addresses the problem of providing a modified resistant starch which provides improvement to rough texture that is a problem peculiar to food containing a resistant starch, and which, when used for food that is intended to be low in carbohydrates, does not compromise the smooth and palatable texture inherent in said food. A method for producing a modified resistant starch according to the present invention comprises a step for adding 5-75 parts by mass of water to 100 parts by mass of a resistant starch and heating the resistant starch. As a result of the step, the average particle diameter of the resistant starch after being heated becomes 1.20-1.50 times of the average particle diameter of the resistant starch before being heated.

Description

Method for producing modified 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] Patent Document 1 describes a method for producing dietary fiber starch, which is starch with a total dietary fiber content of 50% or more, comprising steps of heat-treating starch at a temperature below its gelatinization temperature, phosphorylating it, and then heat-treating it again at a high temperature, and describes heat-treating conditions for the phosphorylated starch as heat-treating it at a temperature above its gelatinization temperature, 80 to 95°C, with shaking for 1 to 30 minutes. Patent Document 2 describes another method for producing the dietary fiber starch, which comprises steps of performing high-temperature heat treatment and ultrasonic treatment while cross-linking rice starch, and describes high-temperature heat-treating conditions as heat-treating it at 80 to 95°C with shaking for 1 to 10 minutes. The production methods described in Patent Documents 1 and 2 were developed in consideration of the problem that when modified starch such as phosphate-crosslinked starch is applied to liquid foods such as mayonnaise, it tends to separate due to its low emulsifying power, and it is said that this production method can produce dietary fiber starch with enhanced emulsifying power.

[0005] Patent Document 3 describes yet another method for producing the dietary fiber starch, which comprises a step of phosphorylating and heat-moisture treating starch, followed by a further heat-moisture treatment, and describes conditions for the latter heat-moisture treatment (i.e., heat-moisture treatment of phosphorylated starch) as follows: the moisture content of the starch to be treated is adjusted to about 10 to 80% by weight, based on the weight of the starch in a dry state, and then the starch is heat-treated at a temperature of about 65 to 160° C. for 0.25 to 24 hours. The production method described in Patent Document 3 was devised in view of the problem that the dietary fiber content is significantly reduced when dietary fiber starch is subjected to extrusion treatment using an extruder, and it is claimed that this production method can produce dietary fiber starch that can maintain a total dietary fiber content of 50% or more even after extrusion treatment.

[0006] US Patent Application Publication No. 2012 / 0132197 US Patent Application Publication No. 2011 / 0129579 European Patent No. 1836903

[0007] An object of the present invention is to provide a modified 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 with a pleasant feel to the tongue of the food when used in foods for the purpose of reducing carbohydrate content.

[0008] The present invention provides a method for producing a modified resistant starch, which comprises a step of adding 5 to 75 parts by mass of water to 100 parts by mass of resistant starch and then heat-treating the resistant starch, wherein the average particle size of the resistant starch after the heat treatment is 1.20 to 1.50 times the average particle size of the resistant starch before the heat treatment.

[0009] 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.

[0010] 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.

[0011] 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 of them may be used in combination.

[0012] As can be seen from the above description of RS1 to RS4, resistant starch may contain impurities (substances that cannot be completely removed by refining the 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 aforementioned 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 starches, 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 a processed starch that has been subjected to at least phosphate crosslinking, and may also be subjected to processing other than phosphate crosslinking (e.g., pregelatinization).

[0013] In this specification, the term "dietary fiber content" refers to a value determined based on 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.).

[0014] 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.).

[0015] 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 also not particularly limited, and may be appropriately selected depending on the intended use of the resulting modified resistant starch, etc. For example, from the viewpoint of the balance between the handleability of the modified resistant starch and the texture of foods using it, 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.

[0016] In this specification, the "average particle size" refers to the particle size at which the cumulative amount, starting from the smallest particle, is 50% of the total in a cumulative volumetric particle size distribution curve of 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.).

[0017] The production method of the present invention includes the steps of adding 5 to 75 parts by mass, preferably 15 to 65 parts by mass, and more preferably 25 to 55 parts by mass of water to 100 parts by mass of resistant starch, and then heat-treating the resistant starch. The resistant starch that has undergone this step is the modified resistant starch that is the target product of the present invention.

[0018] In the heat treatment, the water added to the treatment target (resistant starch) may be a liquid or a gas, and examples thereof include water, saturated steam, and superheated steam. Heating methods used in the heat treatment include, for example, 1) a method in which a heat medium such as hot air is directly brought into contact with the treatment target (resistant starch), and 2) a method in which the treatment target is indirectly heated in a high-humidity atmosphere. The apparatus used to perform the heat treatment is not particularly limited, and examples include a kiln, autoclave, steam oven, and single- or twin-screw extruder. One example of the heat treatment includes a method in which the treatment target is hydrated, then sealed in a sealed container such as an aluminum pouch, and heated together with the sealed container in a kiln, oil heater, oil bath, autoclave, or the like. Another example of the heat treatment includes a method in which the treatment target is hydrated, then introduced into a sealed container, and saturated steam is introduced into the container to heat the treatment target under pressure, while stirring the treatment target as necessary.

[0019] In the production method of the present invention, the heat treatment results in an average particle size of the resistant starch (modified resistant starch) after the heat treatment that is 1.20 to 1.50 times, preferably 1.25 to 1.45 times, and more preferably 1.25 to 1.40 times, the average particle size of the resistant starch before the heat treatment. Hereinafter, the "ratio of the average particle size of the resistant starch after the heat treatment to the average particle size of the resistant starch before the heat treatment" is also referred to as the "average particle size increase ratio." The modified resistant starch obtained by the production method of the present invention solves the problems associated with conventional resistant starches and, when used in foods, has the effect of not impairing the inherent smooth texture of the food. An average particle size increase ratio of less than 1.20 times or more than 1.50 times is insufficient to improve the rough texture caused by resistant starch in foods containing resistant starch. The average particle size increase ratio can be adjusted by appropriately adjusting the conditions of the heat treatment (amount of water added, heating temperature, heating time, etc.).

[0020] In the production method of the present invention, typically, the starting starch (resistant starch) is subjected to the heat treatment once before obtaining the desired modified resistant starch. For example, in the production method described in Patent Document 3, the starting starch is subjected to two heat treatments (moist heat treatments) before obtaining the desired dietary fiber starch. However, when the starting starch is subjected to multiple heat treatments in this manner, it becomes difficult to control the average particle size increase ratio, and there is a risk that the desired effect of the present invention will not be achieved.

[0021] The average particle size of the resistant starch after the heat treatment, i.e., the modified resistant starch, is not particularly limited, provided that the average particle size increase ratio is 1.20 to 1.50, depending on factors such as the average particle size of the resistant starch before the heat treatment, but is preferably 6 to 45 μm, more preferably 17.5 to 37.5 μm.

[0022] From the viewpoint of ensuring that the effects of the heat treatment are more reliably exhibited, the product temperature (heating temperature) of the treatment target (resistant starch to which moisture has been added) in the heat treatment is preferably 120 to 220°C, more preferably 165 to 220°C, and the time for which the product temperature is maintained (heating time) is preferably 5 to 60 minutes, more preferably 5 to 30 minutes.

[0023] In the production method of the present invention, the modified resistant starch obtained through the heat treatment may be subjected to post-treatments such as drying and pulverization, if necessary. The drying treatment is a treatment for reducing the moisture content of the modified resistant starch, and can be carried out by appropriately using known drying methods such as air drying and hot air drying. The pulverization treatment can be carried out in accordance with conventional methods using known pulverization means such as a pin mill or a roll mill.

[0024] The ratio of the dietary fiber content, calculated on a dry mass basis, of the modified resistant starch (the resistant starch after the heat treatment) to the dietary fiber content, calculated on a dry mass basis, of the resistant starch before the heat treatment (hereinafter also referred to as the "dietary fiber content change rate") is preferably 0.90 or more, more preferably 0.92 or more, from the viewpoint of ensuring that foods using the modified resistant starch of the present invention contain sufficient dietary fiber. Furthermore, the upper limit of the dietary fiber content change rate is preferably 0.99 or less, more preferably 0.98 or less, from the viewpoint of preventing a decrease in texture due to an excess of dietary fiber in foods using the modified resistant starch of the present invention. The dietary fiber content change rate can be adjusted by appropriately adjusting the heat treatment conditions (such as the amount of water added, heating temperature, and heating time).

[0025] The modified 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. The term "dough" as used 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.

[0026] 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.

[0027] 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.

[0028] 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.

[0029] The modified resistant starch obtained by the production method of the present invention (hereinafter also simply referred to as "modified resistant starch") 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 batter, the modified resistant starch may be blended in at the early stage of dough preparation, or may be blended into the dough after preparing it using other powder ingredients and liquid ingredients. For example, in the production of bread using a straight dough method or dough foods using dough, such as noodles or cookies, the modified resistant starch 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 using a sponge dough method, the modified resistant starch may be blended as a sponge dough blending ingredient before the sponge dough fermentation, or may be blended into the main kneading ingredients.

[0030] The modified resistant starch may also be blended into a mix for dough foods (hereinafter also simply referred to as a "mix"). The content of the modified resistant starch 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 to be produced using the mix is ​​the aforementioned bakery food, noodle, 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 modified resistant starch (such as reducing the carbohydrate content of the dough food) with the taste and texture of the dough food.

[0031] The mix typically contains one or more types of cereal flour other than the modified resistant starch. In this specification, the term "cereal flour" refers to a cereal-derived powdery substance at room temperature and normal pressure, and encompasses both 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 unprocessed starches such as tapioca starch, potato starch, cornstarch, waxy cornstarch, wheat starch, and rice starch; and processed starches obtained by subjecting unprocessed starches to one or more of the following treatments: gelatinization, etherification, esterification, acetylation, cross-linking, and oxidation.

[0032] The total content of cereal flours, including the modified resistant starch, 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 of the cereal flours, including the modified resistant starch, is preferably 5 to 90% by mass, and more preferably 10 to 80% by mass, relative to the total mass of the mix.

[0033] 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.

[0034] 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.

[0035] The present invention includes, for example, the following aspects: <1> A method for producing a modified resistant starch, comprising a step of adding 5 to 75 parts by mass of water to 100 parts by mass of resistant starch and then heat-treating the resistant starch, wherein the average particle size of the resistant starch after the heat treatment is 1.20 to 1.50 times the average particle size of the resistant starch before the heat treatment. <2> The method according to <1>, wherein the heat treatment is carried out under conditions in which the product temperature of the resistant starch is maintained at 120 to 220°C for 5 to 60 minutes. <3> The method according to <1> or <2>, wherein the ratio of the dietary fiber content, calculated on a dry mass basis, of the modified resistant starch to the dietary fiber content, calculated on a dry mass basis, of the resistant starch before the heat treatment is 0.9 or more. <4> The method according to any one of <1> to <3>, wherein the resistant starch is a processed starch that has been at least cross-linked with phosphate.

[0036] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the following examples.

[0037] Examples 1 to 9, Comparative Examples 1 to 6 A predetermined amount of water was added to 100 parts by mass of resistant starch and mixed, the mixture was spread evenly on a tray container, and the contents of the tray container were heat-treated using a flat oven (manufactured by Tokura Shoji Co., Ltd.) to produce modified resistant starches. The amount of water added and the heat-treatment conditions (heating temperature, heating time) are shown in Tables 1 and 2 below. The resistant starch used was a phosphate cross-linked starch (manufactured by Matsutani Chemical Industry Co., Ltd., trade name "Pine Starch RT", dietary fiber content 95% by mass calculated on starch dry matter basis).

[0038] [Test Example] 33.5% by mass of the prepared modified resistant starch, 33.5% by mass of soft flour, 30% by mass of sugar, and 3% by mass 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 using 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 control hotcake was also prepared in the same manner as above, except that the resistant starch used as the raw material for the modified resistant starch was used instead of the modified resistant starch. The resulting hotcakes were tasted by 10 expert panelists, who evaluated the texture (lessness of roughness) according to the following criteria. The results are shown in Tables 1 and 2 below as the average scores of the 10 panelists.

[0039] <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.

[0040]

[0041] As shown in Table 1, in each Example, the amount of water added during the heat treatment was 5 to 75 parts by mass per 100 parts by mass of resistant starch, and the average particle size increase ratio was 1.20 to 1.50 times, and therefore the texture of the pancakes was superior to that of Comparative Examples 1 and 2, which did not meet these requirements.

[0042]

[0043] As shown in Table 2, the average particle size increase ratio in each Comparative Example was less than 1.20 times, resulting in a pancake texture inferior to that of each Example. Since the heating temperature or heating time in the heat treatment in each Comparative Example in Table 2 was different from that in each Example in Table 2, it can be seen that the average particle size increase ratio can be adjusted by appropriately adjusting the heating temperature and heating time in the heat treatment.

[0044] According to the present invention, a modified resistant starch is provided which improves the rough texture that is a problem specific to foods containing resistant starch, and which, when used in foods for the purpose of reducing carbohydrate content, does not impair the inherent smooth texture that is pleasant to the tongue of the food.

Claims

1. A method for producing a modified resistant starch, comprising the step of adding 5 to 75 parts by mass of water to 100 parts by mass of resistant starch and then heat-treating the resistant starch, wherein the average particle size of the resistant starch after the heat treatment is 1.20 to 1.50 times the average particle size of the resistant starch before the heat treatment.

2. The method according to claim 1, wherein the heat treatment is carried out under conditions in which the product temperature of the resistant starch is maintained at 120 to 220°C for 5 to 60 minutes.

3. The manufacturing method described in claim 1 or 2, wherein the ratio of the dietary fiber content, calculated as a dry mass, of the modified resistant starch to the dietary fiber content, calculated as a dry mass, of the resistant starch before the heat treatment is 0.9 or more.

4. 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.

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