JP2015218201A - Modified starch and use thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide new modified starch that can improve textures, especially flexibility and softness of noodles, useful for texture improvement of foods, and can suppress aged deterioration of the textures.SOLUTION: Hypochlorous acid or its salt is added to a suspension of raw material starch so that the available chlorine concentration is 50-800 ppm based on starch dry mass, and the suspension is agitated at pH 7.0-10.0 and then subjected to acetylation treatment using acetic anhydride so that the content of an acetyl group is 1.5-2.5 mass%, to obtain modified starch. Preferably, the modified starch has a value of bottom viscosity/peak viscosity, measured by amylograph analysis at 6 mass%, of 0.2-0.5. The raw material starch is preferably tapioca starch.

Description

  The present invention relates to modified starch and uses thereof.

  Conventionally, when producing noodles, starch, thickener, gluten, emulsifier, etc. for the purpose of improving noodle making, improving storage stability, improving taste, improving yield, preventing discoloration and improving hue Additives such as are used.

  Among them, various processed starches that change the structure and properties of starch are used in the food industry, and various processed starches as shown in the following patent documents are used in noodles to improve quality. It has been.

  For example, Patent Document 1 below discloses a method for producing noodles by blending a modified starch such as hydroxypropylated starch or acetylated starch for the purpose of improving the hot water restoration property and texture of the noodles. . In addition, in Patent Document 2 below, by blending a phosphoric acid cross-linked starch such as hydroxypropylated phosphoric acid cross-linked starch or acetylated phosphoric acid cross-linked starch, by blending a thermocoagulable protein material, quality by long-term storage Has disclosed a method for producing noodles in which the deterioration of the material is hardly observed.

  Further, in Patent Document 3 below, the tapioca starch is subjected to hydroxypropylation or acetylation, and by adding a modified starch obtained by treating with a small amount of sodium hypochlorite, elasticity, elasticity A method for producing noodles excellent in feeling is disclosed. In Patent Document 4 below, starch is reacted with hypochlorous acid or a salt thereof, and then processed to obtain processed starch for food (hydroxypropylation treatment, phosphoric acid crosslinking treatment, and vinyl acetate monomer). A method for producing bleached processed starch for foods is described which performs one or more processing selected from the group consisting of acetylation treatments used.

Japanese Patent Publication No.62-62137 Japanese Patent Laid-Open No. 10-215803 JP 2005-27643 A JP 2011-256273 A

  Various processed starches have been used to improve the texture of noodles, but the processed starch that has been used in the past improves the texture of the noodles, specifically the texture of the noodles. In addition, it is difficult to suppress the deterioration of the texture with time.

  Accordingly, an object of the present invention is to provide a processed starch that is useful for improving the texture of foods, particularly improving the texture such as the flexibility and softness of noodles, and further suppressing the deterioration of the texture over time. There is to do.

  As a result of intensive studies to solve the above-mentioned problems, the present inventors added hypochlorous acid or a salt thereof to the raw starch, treated under predetermined conditions, and then subjected to acetylation with acetic anhydride. The processed starch obtained by this has found that an excellent texture-improving effect can be obtained by adding it to food, and the present invention has been completed.

  That is, in the first aspect of the present invention, hypochlorous acid or a salt thereof is added to a suspension of the raw material starch so that the effective chlorine concentration with respect to the dry mass of the starch is 50 to 800 ppm, and the pH is 7.0 to 10. The present invention provides a novel modified starch obtained by performing acetylation treatment with acetic anhydride so as to have an acetyl group content of 1.5 to 2.5% by mass after stirring at 0.

  In the said invention, it is preferable in the amylography analysis in 6 mass% that the value of the bottom viscosity / peak viscosity is 0.2-0.5.

  Moreover, it is preferable that the carboxy group content in the modified starch is less than 0.1% by mass, and that the modified starch shows a negative in the carboxy group confirmation test.

  Moreover, it is preferable that the said raw material starch is a tapioca starch.

  On the other hand, a second aspect of the present invention provides a material for improving the texture of noodles, which contains the processed starch.

  In the said invention, it is preferable that content of said processed starch is 3-100 mass%.

  On the other hand, the third aspect of the present invention provides noodles produced by adding the processed starch.

  The texture can be improved by using the processed starch obtained by the present invention for foods, particularly noodles. More specifically, the texture such as the flexibility and softness of noodles can be improved. Furthermore, the deterioration of the texture with time can be suppressed.

  The processed starch of the present invention can be obtained by adding hypochlorous acid or a salt thereof to the raw material starch, treating it under predetermined conditions, and then subjecting it to acetylation with acetic anhydride.

  The raw material starch is not particularly limited as long as it is a starch that can be used for foods. Examples include starch, sago starch, and green lily starch. Among these, tapioca starch is particularly preferable. Further, in any starch, in addition to ordinary starch, those modified in breeding techniques or genetic engineering techniques such as urch seeds, waxy seeds, and high amylose seeds may be used.

  The treatment of starch with hypochlorous acid or a salt thereof is preferably carried out so that a carboxy group is not formed in the starch by the oxidation reaction. Specifically, hypoxia is used such that the effective chlorine concentration with respect to the dry starch mass is 50 to 800 ppm, preferably 100 to 600 ppm, more preferably 200 to 400 ppm, in the suspension of the raw material starch suspended in water or the like. Chloric acid or a salt thereof is added, and the starch suspension is treated with hypochlorous acid or a salt thereof under the condition of 7.0 to 10.0, preferably 7.5 to 9.6. Examples of hypochlorous acid salts include sodium hypochlorite, potassium hypochlorite, and calcium hypochlorite.

By treatment with hypochlorous acid or a salt thereof, the starch is reduced in molecular weight and suppressed in swelling. In this case, if the effective chlorine concentration with respect to the dry starch mass is less than 50 ppm, the swelling inhibiting action is weak and the desired effect cannot be obtained. If the effective chlorine concentration with respect to the starch dry mass exceeds 800 ppm, the swelling inhibiting action is excessive. There is a problem that the intended effect cannot be obtained. Moreover, when it is processed until the carboxy group is formed in the starch, there is a problem that the low molecular weight is promoted and partly solubilized and not suitable for noodles.
Moreover, when the pH of the starch suspension is less than 7.0, the surface of the noodles is rough, which is not preferable. When the pH exceeds 10.0, the texture of the noodles is strong and brittle, which is not preferable.

The effective chlorine concentration means that the oxidizing power of hypochlorous acid water is converted to iodine (I ₂ ) by reaction with potassium iodide (KI) by a chemical reaction represented by the following formula (1), and the concentration is calculated. It is a value measured and converted into a chlorine (Cl ₂ ) concentration. Iodine (I ₂ ) can be quantified by a known iodine titration method or the like. For example, iodine (I ₂ ) is added to a starch solution to cause coloration, and colorimetric titration with a sodium thiosulfate (Na ₂ S ₂ O ₃ ) solution is performed by a chemical reaction represented by the following formula (2). Is mentioned. When the effective chlorine existing percentage of hypochlorous acid water is 100%, the concentration of hypochlorous acid and / or hypochlorite ion and the effective chlorine concentration are equal.

NaClO + 2KI + H ₂ SO ₄ → I ₂ + K ₂ SO ₄ + NaCl + H ₂ O (1)
I ₂ + 2Na ₂ S ₂ O ₃ → 2NaI + Na ₂ S ₄ O ₆ (2)

  The content of carboxy groups formed in starch by treatment with hypochlorous acid or a salt thereof can be quantified according to a conventional method. For example, it can be quantified according to the method of the purity test of the carboxy group of acetylated oxidized starch described in Ministry of Health, Labor and Welfare Notification No. 485. Moreover, the confirmation test of the carboxy group produced | generated in starch can be performed according to the method of the confirmation test of the carboxy group of the acetylation oxidation starch described in Ministry of Health, Labor and Welfare Notification No. 485, for example.

  Therefore, using such a test, it can be confirmed that no carboxy group is formed in the starch by the treatment of the starch with the above hypochlorous acid or a salt thereof. For example, the starch obtained by treating with hypochlorous acid or a salt thereof has a carboxy group content of less than 0.1% by mass, and the starch is treated to be negative in the carboxy group confirmation test. It is preferable.

  After the treatment with hypochlorous acid or a salt thereof, a residual chlorine removal treatment may be performed. Here, the residual chlorine removal treatment means removal of effective chlorine by adding a reducing agent such as sodium hydrogen sulfite, sodium sulfite, sodium pyrosulfite, sodium ascorbate to the starch suspension. The reducing agent may be either a solid or a solution. Moreover, the addition amount of a reducing agent can be suitably adjusted according to the addition amount of hypochlorous acid, and the residual chlorine amount which remains. The amount of residual chlorine can be confirmed by the KI check method (described later).

  The starch treated with hypochlorous acid or a salt thereof may be subjected to acetylation treatment as it is, or may be subjected to acetylation treatment once dehydrated and dried and then resuspended in water.

  The acetylation treatment is performed using acetic anhydride so that the acetyl group content of the obtained processed starch is 1.5 to 2.5% by mass, more preferably 2.0 to 2.5% by mass. As will be apparent from the examples described later, by setting the acetyl group content within the above range, the texture of the noodles such as flexibility, softness and sushi can be improved. If the acetyl group content is less than 1.5% by mass, it is not preferable because it is hard and brittle. Further, when an acetylating agent other than acetic anhydride such as a vinyl acetate monomer is used, the bottom viscosity / peak viscosity value increases, and the texture improvement effect cannot be obtained. Considering the efficiency of the acetylation reaction and the standard of food additives in the Food Sanitation Law, the acetyl group content is preferably 2.5% by mass or less. The acetyl group content can be appropriately adjusted by setting and selecting conditions such as the amount of acetic anhydride added, reaction temperature, reaction pH, reaction time, and the like.

  The processed starch of the present invention has a bottom viscosity / peak viscosity value of 0.2 to 0.5, preferably 0.3 to 0.4, in an amylographic analysis at 6% by mass. More preferred. The value of the bottom viscosity / peak viscosity is one index indicating the degree of the swelling suppression effect of starch, and the higher the bottom viscosity / peak viscosity value, the stronger the swelling suppression effect. When the value of the bottom viscosity / peak viscosity is less than the above range, gelatinization is fast, and when used for noodles, only the surface of the noodle strings is gelatinized, and there is a tendency that water does not penetrate into the inside and the core remains. When the value of the bottom viscosity / peak viscosity exceeds the above range, gelatinization is insufficient, and the intended texture improving effect tends to be difficult to obtain. The value of bottom viscosity / peak viscosity can be adjusted by the effective chlorine concentration of hypochlorous acid or its salt when processing starch, or the processing pH. The higher the effective chlorine concentration, the lower the bottom of the processed starch obtained. The viscosity / peak viscosity value tends to increase, and the lower the effective chlorine concentration, the lower the bottom viscosity / peak viscosity value of the resulting processed starch. Further, the higher the processing pH, the higher the bottom viscosity / peak viscosity value of the obtained processed starch tends to increase, and the lower the processing pH, the lower the bottom viscosity / peak viscosity value of the resulting processed starch tends to decrease. is there.

  Hereinafter, the KI check method, measurement of acetyl group content, amylography analysis, carboxy group content, and carboxy group confirmation test will be described.

  The KI check method can be implemented as follows.

  Add a few drops of 1N sulfuric acid to the filter paper and add a few drops of starch suspension on top of it to acclimate. When a few drops of 10% potassium iodide aqueous solution is added to it, and discoloration is observed, it means that chlorine remains. When no discoloration was observed, chlorine did not remain, meaning that the residual chlorine removal process was completely performed.

  The acetyl group content can be quantified by the following method.

  A starch sample (5.0 g) is accurately weighed and suspended in 50 mL of water, a few drops of phenolphthalein test solution is added, and 0.1 mol / L sodium hydroxide solution is added dropwise until the solution turns slightly red, then 0.45 mol / L Add exactly 25 mL of sodium hydroxide solution, cap, and shake vigorously for 30 minutes, being careful not to let the temperature rise above 30 ° C. Titrate excess sodium hydroxide with 0.2 mol / L hydrochloric acid. The end point is when the slight red color of the liquid disappears. Separately, perform a blank test to correct. A free acetyl group content is calculated | required by following formula (3), and also dry matter conversion is performed.

Acetyl group content (mass%) = (es) × f × 0.043 × 100 / w (3)
In the above formula (3), e: blank test titration (mL), s: sample titration (mL), f: titer of 0.2 mol / L hydrochloric acid, w: sample dry substance amount (g) .

  The amylography analysis can be performed as follows.

  A starch slurry of 6% by mass in terms of solid content was prepared, the start temperature of measurement was started at 35 ° C., the temperature was raised to 95 ° C. at 1.5 ° C./min, and then the gelatinization of starch was performed under the condition of maintaining 95 ° C. for 30 minutes Measure characteristics. The maximum viscosity recorded until reaching 95 ° C. is read from the obtained amylogram (temperature-starch viscosity curve), and this is used as the peak viscosity. Further, when the viscosity is lowered after the peak viscosity is expressed, the viscosity recorded when the temperature is maintained at 95 ° C. for 30 minutes is read and used as the bottom viscosity.

  The carboxy group content can be quantified by the following method.

  Add 50 mL of 0.1N hydrochloric acid to a starch sample with a dry substance amount of 5.0 g, stir for 30 minutes, and suction filter using a glass filter with a pore size of 10 to 16 μm. Distilled water until the filtrate does not react with chloride. Continue cleaning with. Chloride reaction can be confirmed by adding a 0.1N silver nitrate solution to the filtrate. If the filtrate becomes cloudy, a chloride reaction has occurred. The residue is suspended in 300 mL of water, heated on a water bath with stirring, and gelled. After further heating for 15 minutes, 3 drops of phenolphthalein indicator are added and immediately colored with 0.1N sodium hydroxide solution. Titration quickly. In the blank test, 50 mL of distilled water is added to a starch sample having a dry substance amount of 5.0 g, stirred for 30 minutes, suction filtered using a glass filter having a pore size of 10 to 16 μm, and washed with 200 mL of distilled water. The residue is suspended in 300 mL of distilled water, heated on a water bath with stirring and gelled. After further heating for 15 minutes, 3 drops of phenolphthalein indicator are added and immediately colored with 0.1N sodium hydroxide solution. Titrate quickly until The carboxy group content is calculated using the following formula.

Carboxy group content (% by mass) = (A−B) × F × 0.45 ÷ 5
A: Sample titration (mL)
B: Blank test titration (mL)
F: 0.1N sodium hydroxide titer

  The confirmation test of a carboxy group can be performed as follows.

  A 0.5 g starch sample is suspended in 25 ml of a 1% methylene blue solution, stirred occasionally for 5-10 minutes, the supernatant is decanted and the precipitate is washed thoroughly with water. Part of the resulting precipitate is collected and observed with a microscope. In microscopic observation, the case where dark blue coloration is observed in starch granules is positive, and the case where dark blue coloration is not observed is negative. In addition, if it is determined that it is difficult to distinguish between positive and negative, a false positive is assumed.

  Below, the one aspect | mode of the preparation method of the modified starch of this invention is shown.

  After adding water to starch as a raw material to prepare a starch suspension having a concentration of 20 to 45% by mass, preferably 36 to 43% by mass, for example, alkali such as sodium hydroxide, calcium hydroxide, sodium carbonate, etc. The agent is added to the starch suspension to adjust the pH to 7.0 to 10.0, preferably 7.5 to 9.5. Next, after adding hypochlorous acid or a salt thereof to the starch suspension so that the effective chlorine concentration with respect to the dry mass of starch is 50 to 800 ppm, preferably 100 to 600 ppm, more preferably 200 to 400 ppm, The temperature of the suspension is kept at 10 to 45 ° C, preferably 25 to 35 ° C, and stirred for 5 to 90 minutes, preferably 10 to 60 minutes. Thereafter, if necessary, a reducing agent such as sodium bisulfite, sodium sulfite, sodium pyrosulfite, or sodium ascorbate is added to the starch suspension to remove effective chlorine. Next, the starch suspension is adjusted to pH 8-11, preferably pH 8.5-10.5. Subsequently, after adding 3-15 mass% of acetic anhydride with respect to starch, the temperature of starch suspension is kept at 10-45 degreeC, Preferably it is 20-40 degreeC, More preferably, it is 25-35 degreeC, The reaction is performed for 240 minutes, preferably 60 to 180 minutes. Thereafter, for example, an acid such as hydrochloric acid is added to adjust the starch suspension to a pH of less than 7.5, preferably to a pH of 2 to 7, more preferably to a pH of 5 to 7. The starch slurry subjected to the above treatment is washed with water, dehydrated, dried, sieved and packaged. Furthermore, in the process from the adjustment to packaging, the starch may be readjusted to a desired pH by adding a pH adjuster.

  The processed starch of the present invention can exhibit an excellent texture improvement effect when added to foods, particularly noodles. For example, as shown in the Examples described later, the texture such as the softness and suppleness of the noodles can be improved, and the deterioration of the texture over time can be suppressed. Therefore, it is useful as an active ingredient of a material for improving the texture of noodles. The texture improving material may contain components other than the processed starch, or the texture improving material may be composed of the processed starch itself. Examples of the components other than the processed starch include cereal flours, starches other than the processed starch, emulsifiers, gluten, proteins, fats and oils, inorganic salts, saccharides, dyes, preservatives, fragrances, polysaccharides and the like. It is done. The content of the modified starch in the texture improving material is typically 3 to 100% by mass, and more typically 10 to 50% by mass.

  Processed starch of the present invention includes, for example, udon, buckwheat, fried noodles, somen, hiya wheat, kishimen, Chinese noodles, cold noodles, spaghetti, gyoza peel, wonton peel and other raw noodles, crab noodles (chilled noodles, cooked) Noodles), steamed noodles, long-life noodles, packaged steamed noodles, frozen noodles, instant noodles, etc., and can improve the texture. There is no particular limitation on the method of adding to these noodles, the processed starch as it is or prepared as a noodles food texture improver, blended into the raw material or part thereof, or added during the manufacturing process, What is necessary is just to make it contain in a predetermined amount in the foodstuffs, such as mixing. Although there is no restriction | limiting in particular in the addition amount, It is preferable to add 5-30 mass% of said processed starch in raw material solid content, and it is more preferable to add 10-20 mass%.

  EXAMPLES The present invention will be described below with reference to examples, but the present invention is not limited to the following examples.

[Preparation of modified starch]
(Starch sample 1)
Water was added to 300 g of raw tapioca starch (dry substance amount) to prepare a 40% by mass starch suspension, and 3% sodium hydroxide was added to adjust the pH to 9. To this, 26 g of acetic anhydride was added over 180 minutes, and 3% sodium hydroxide was added thereto to maintain the pH of 8-9, followed by stirring to carry out an acetylation reaction. Next, 9% hydrochloric acid was added to adjust the pH to 7 to complete the acetylation reaction, 1.5 L of water was added for dehydration, and 150 mL of water was further added for dehydration and drying. The processed tapioca starch of the starch sample 1 shown in FIG.

(Starch samples 2-12, 14, 15)
Water is added to 300 g of raw tapioca starch (dry substance amount) to prepare a 40% by mass starch suspension, and 3% sodium hydroxide is added to adjust the pH to 6.5 (starch samples 3, 10). 7.5 (starch samples 2, 4, 8, 11, 14, 15), 8.5 (starch samples 5, 9), 9.5 (starch sample 6), 10.5 (starch sample 7), 11 To 0.0 (starch sample 12). Sodium hypochlorite has an effective chlorine concentration of 50 ppm (starch sample 2), 200 ppm (starch samples 3-7, 15), 400 ppm (starch samples 8, 9), 800 ppm (starch samples 10-12) based on the amount of starch dry substance. , 1000 ppm (starch sample 14), respectively, and after stirring for 30 minutes, the pH was measured. Thereafter, sodium pyrosulfite was added until no effective chlorine was detected from the starch suspension in the KI check. Thereafter, 3% sodium hydroxide was added to adjust the pH to 9. To this, 26 g of acetic anhydride (starch samples 2 to 12, 14) and 12 g (starch sample 15) were added over 180 minutes, respectively, and 3% sodium hydroxide was added to maintain pH 8 to 9 Stirring and acetylation reaction were performed. Next, 9% hydrochloric acid was added to adjust the pH to 7 to complete the acetylation reaction, 1.5 L of water was added for dehydration, and 150 mL of water was further added for dehydration and drying. Processed tapioca starches of starch samples 2-12, 14, and 15 shown in FIG.

(Starch sample 13)
Water is added to 300 g of raw tapioca starch (dry substance amount) to prepare a 40% by mass starch suspension, 6 g of sodium sulfate is added, and then 3% sodium hydroxide is added to adjust the pH to 11.5. Adjusted. Sodium hypochlorite was added to an effective chlorine concentration of 800 ppm with respect to the amount of starch dry substance, and stirring was maintained for 30 minutes, and then the pH was measured. Thereafter, sodium pyrosulfite was added until no effective chlorine was detected from the starch suspension in the KI check. Thereafter, 3% sodium hydroxide was added to adjust the pH to 9. To this, 26 g of acetic anhydride was added over 180 minutes, and 3% sodium hydroxide was added thereto to maintain the pH of 8-9, followed by stirring to carry out an acetylation reaction. Next, 9% hydrochloric acid was added to adjust the pH to 7 to complete the acetylation reaction, 1.5 L of water was added for dehydration, and 150 mL of water was further added for dehydration and drying. The processed tapioca starch of the starch sample 13 shown in FIG.

(Starch Sample 16)
Water was added to 300 g of raw tapioca starch (dry substance amount) to prepare a 40% by mass starch suspension, and 3% sodium hydroxide was added to adjust the pH to 7.5. Sodium hypochlorite was added so as to have an effective chlorine concentration of 200 ppm with respect to the amount of starch dry substance, and stirring was maintained for 30 minutes, and then the pH was measured. Thereafter, sodium pyrosulfite was added until no effective chlorine was detected from the starch suspension in the KI check. Thereafter, the pH was adjusted to 10 by adding sodium carbonate. To this, 20 g of vinyl acetate monomer was added and stirring was maintained for 30 minutes. Next, 9% hydrochloric acid was added to adjust the pH to 7 to complete the acetylation reaction, 1.5 L of water was added for dehydration, and 150 mL of water was further added for dehydration and drying. The processed tapioca starch of the starch sample 16 shown in FIG.

  The acetyl group content was measured for the modified starches of starch samples 1-16. Moreover, the amylography analysis in 6 mass% was performed, and the value of the bottom viscosity / peak viscosity was computed. Furthermore, the measurement and confirmation test of carboxy group content were implemented. The results are summarized in Table 1.

[Test Example 1]
Chinese noodles were prepared using the starch samples 1 to 16 (test sections 1 to 16). Specifically, Group A raw materials shown in Table 2 are mixed, premixed and dissolved Group B raw materials are added, kneaded to form a noodle band, and aged for 1 hour after rolling (1.3 mm And then cut out with a cutting blade (Japanese Industrial Standard JIS # 20: groove width 1.5 mm). 100 g of the cut noodle strings were each boiled in 2 L of hot water to a yield of 180% by mass. In addition, "kansui CS" (trade name) manufactured by Oriental Yeast Co., Ltd. was used as the Kansui.

  Boiled Chinese noodles were washed with running water, then cooled with ice water, and 4% by mass of a loosening agent “Soya Up M3000” (trade name, manufactured by Fuji Oil Co., Ltd.) was added to the noodles. Each was evaluated after storage for 2 days. The evaluation was performed in six stages of 0 to 5 points for softness, suppleness, brittleness, and surface sag, and a total evaluation was performed by 5 panelists. Regarding the softness, the harder the evaluation was closer to 0 point, and the softer the evaluation was closer to 5 points. With regard to suppleness, the harder one was evaluated closer to 0 point, and the supple one was evaluated closer to 5 points. With regard to brittleness, the evaluation was closer to 0 point for the more brittle ones, and the evaluation was closer to 5 points for the less brittle ones. Regarding surface sag, the rougher the evaluation, the closer to 0 point, and the smoother the evaluation, the closer to 5 points. Regarding the total score of the overall evaluation, 15 points or more for the evaluation after storage for 1 day at 5 ° C (D + 1), 14 points or more for the evaluation after storage for 2 days at 5 ° C (D + 2) did. The results are shown in Table 3.

  As a result, the following became clear.

  (1) After adding sodium hypochlorite so that the effective chlorine concentration with respect to the dry mass of starch is 50 to 800 ppm and stirring in the range of pH 7.0 to 10.0, acetyl group content is 1 with acetic anhydride. D + 1 (evaluation after storage for 1 day) for starch samples 2, 4 to 6, 8, 9, and 11 obtained by performing acetylation treatment to be in the range of 0.5 to 2.5% by mass And D + 2 (evaluation after storage for 2 days) gave a favorable texture. In particular, the starch sample 4 was very preferable because it showed a soft, supple and sticky texture.

  (2) In the case of starch sample 1 where treatment with sodium hypochlorite is not performed, even if the other conditions are the preparation conditions described in (1) above, lack of suppleness at the D + 1 stage and good brittleness It was not a texture.

  (3) In the case of starch samples 3, 7, 10, 12, and 13 where the pH conditions during the treatment with sodium hypochlorite are outside the range of the preparation conditions described in (1) above, other conditions No noodles with improved texture and deterioration over time were obtained even under the preparation conditions described in (1) above.

  (4) In the case of the starch sample 14 to which sodium hypochlorite is added so that the effective chlorine concentration with respect to the dry mass of starch is 1000 ppm, the other conditions are the preparation conditions described in (1) above. Noodles with improved texture and deterioration over time could not be obtained. In particular, the deterioration from D + 1 to D + 2 was remarkable.

  (5) In the case of starch sample 15 in which the addition amount of acetic anhydride as an acetylating agent is reduced to an acetyl group content of 1.19% by mass, the other conditions are the preparation conditions described in (1) above. However, it was lacking in flexibility at the D + 1 stage, and it was brittle and not good.

  (6) Furthermore, in the case of starch sample 16 using vinyl acetate monomer instead of acetic anhydride as an acetylating agent, even if the other conditions are the preparation conditions described in (1) above, a hard texture is obtained. , D + 2 lacked flexibility and was brittle and unsatisfactory.

  Although the details of the mechanism of such a texture improving effect are unclear, the processed starch obtained by the preparation conditions of (1) above shows a weak swelling suppressing effect and soft properties when gelatinized. . The presence of the above modified starch in the noodles allows the water that has penetrated to the center of the noodles to swell and gelatinize in a balanced manner, providing a soft and supple texture and suppressing deterioration over time such as aging due to storage. It is thought that.

Claims (7)

  Hypochlorous acid or a salt thereof is added to the raw starch suspension so that the effective chlorine concentration with respect to the dry mass of the starch is 50 to 800 ppm, and the mixture is stirred at pH 7.0 to 10.0. Processed starch obtained by performing acetylation treatment so that the acetyl group content is 1.5 to 2.5 mass%.   The processed starch according to claim 1, wherein the bottom viscosity / peak viscosity value is 0.2 to 0.5 in an amylographic analysis at 6% by mass.   The processed starch according to claim 1 or 2, wherein the processed starch has a carboxy group content of less than 0.1% by mass, and the processed starch shows a negative result in a carboxy group confirmation test.   Processed starch as described in any one of Claims 1-3 whose said raw material starch is tapioca starch.   A texture improving material for noodles, comprising the modified starch according to any one of claims 1 to 4.   The material for improving the texture of noodles according to claim 5, wherein the content of the processed starch is 3 to 100% by mass.   Noodles manufactured by adding the modified starch according to any one of claims 1 to 4.