JP5209256B2 - Starch with high thickening effect and method for producing the same - Google Patents

Description

The present invention relates to starch having a high thickening effect and a method for producing the same, and more particularly to a bleached starch having a thickening effect higher than that of untreated starch and having a reduced chlorine odor and a method for producing the same.

In general, starch absorbs water when heated in the presence of water and the particles swell, and when the swelling reaches a physical limit, the particles collapse. As the disintegration progresses, the grains become fragmented and eventually disappear completely. In these series of phenomena, the viscosity changes according to the state of starch granules. For example, when the starch is simply suspended in water, the particles hardly absorb water, so that the viscosity is hardly expressed. As this is heated, the grains swell and develop viscosity. Thereafter, when the heating temperature rises, the swelling of the grains is promoted and the viscosity increases. As the grain swells just before the physical limit, the viscosity is also maximized. After that, when the grain collapses, the viscosity starts to decrease, and the viscosity decreases until the disintegrated grains are fragmented to a certain degree.

Starch is used in various foods, most of which are aimed at improving the texture by thickening the starch during heating. Typical examples include improving and stabilizing the viscosity and shape retention of sauces, sauces, dressings, and fillings, and imparting and stabilizing viscoelasticity of aquatic livestock kneaded foods, dim sums, noodles, Japanese and Western confectionery, etc. Can be mentioned.

However, as described above, starch has the property of being disintegrated by heating above a certain level, so that the viscosity decreases depending on the heating and cooking conditions, and the expected viscosity may not be obtained. This phenomenon is easily promoted by mechanical shear, pressurization, extreme acidity or alkalinity.

This phenomenon can be improved by making it difficult for the starch to disintegrate. That is, by strengthening the grain structure of starch, it is possible to suppress the swelling of starch and change it to a property that does not easily collapse. Examples of a method for strengthening the grain structure include a method in which a cross-linked structure is introduced chemically or intermolecularly in starch, such as phosphoric acid cross-linking and acetylated adipic acid cross-linking. On the other hand, a method of changing the crystal structure of starch granules by physical processing such as wet heat treatment or hot water treatment can be mentioned.

However, since crosslinking agents such as phosphorous oxychloride, sodium trimetaphosphate, and adipic acid used in chemical modification methods such as phosphoric acid crosslinking and acetylated adipic acid crosslinking are expensive, a cheaper method for strengthening the grain structure is required. ing. Also in the physical processing method, the equipment required for the wet heat treatment is very expensive, and the hot water treatment requires an extremely long reaction time, so it is difficult to say that both are inexpensive production methods.

As a method for strengthening the grain structure relatively inexpensively, a method using sodium hypochlorite is known. Sodium hypochlorite is a substance commonly used as a bleaching or bactericidal agent for starch. However, Non-Patent Document 1 describes that, by adding a small amount of this to corn starch, the grain structure is strengthened and heated. It has been shown that the thickening can be increased. It is speculated that this phenomenon may be a result of intermolecular crosslinking by CHO groups. Patent Document 1 describes that the addition of a small amount of sodium hypochlorite improves the thickening of waxy corn starch. Patent Document 2 describes a method for producing glutinous starch treated with hypochlorous acid, and describes performing hypochlorous acid treatment on the alkali side. Patent Document 3 describes the use of L-ascorbic acid in a method for producing oxidized starch treated with an oxidizing agent such as hypochlorite to remove the oxidizing agent remaining in the starch. . However, when sodium hypochlorite is used in the methods shown in these documents, even if the residual chlorine removal treatment is completely performed after the reaction is completed, a strong chlorine odor remains in the starch. The problem is that the aroma and flavor are significantly reduced.
In Patent Document 4, a large amount of sodium hypochlorite is added to starch and subjected to an oxidation treatment, followed by an alkali treatment, and then a small amount of sodium hypochlorite is added to bleach the starch, and further the residual chlorine. Is described. However, in the method described in Patent Document 4, a strong chlorine odor remains in the starch because a large amount of sodium hypochlorite is used in the initial oxidation treatment. Furthermore, since the starch is remarkably reduced in viscosity by the first oxidation treatment, the thickening effect of starch can be obtained even after subsequent alkali treatment, addition of a small amount of sodium hypochlorite and removal of residual chlorine. Rather, viscosity reduction is promoted.
Starch Science Vol.22 No.1 p. 12-13 (1975) Japanese Patent Laid-Open No. 10-53601 JP 2005-304389 A JP 2004-123959 A Special Table 2002-521530 gazette

In order to completely react with sodium hypochlorite added in the liquid phase reaction, a long reaction time is required. However, if the reaction is performed for a long time, the viscosity of the starch is lowered, and the desired thickening effect is obtained. I can't. Therefore, it is necessary to completely stop the reaction by removing the residual chlorine after performing the reaction for a reaction time such that the intended thickening effect can be obtained. The methods described in Non-Patent Document 1 and Patent Document 1 Then, this residual chlorine removal process is performed at pH 6.0. In this way, when sodium hypochlorite continues to react or remains in a trace amount, if the pH is reduced to below neutral, chlorine gas is generated from the remaining sodium hypochlorite, and chlorine is generated in the starch. Odor remains.

Accordingly, an object of the present invention is to provide a bleached starch having a thickening effect higher than that of untreated starch and having a reduced chlorine odor, and a method for producing the same.

As a result of intensive studies to solve the above problems, the present inventors reacted sodium hypochlorite under high alkalinity (pH 10.5 to 11.5, preferably 10.8 to 11.2). Then, a residual chlorine removal treatment is performed while maintaining high alkalinity (pH 10.5 to 11.5, preferably 10.8 to 11.2), and no chlorine remains in the starch finally obtained, and By making the carboxyl group content less than 0.1% by weight, it has been found that a bleaching starch having a thickening effect higher than that of untreated starch and having a reduced chlorine odor can be obtained, thereby completing the present invention. It came to.

The bleached starch of the present invention according to an embodiment is reacted with sodium hypochlorite under high alkalinity (pH 10.5 to 11.5, preferably 10.8 to 11.2), and then highly alkaline (pH 10). .5 to 11.5, preferably 10.8 to 11.2), the residual chlorine is removed, and no chlorine remains in the finally obtained starch, and the carboxyl group content is 0.1. It is produced so that it may become less than weight%.

Moreover, the manufacturing method of the bleached starch of this invention which concerns on one Embodiment is, after adjusting the pH of starch suspension to 10.5-11.5, Preferably it is 10.8-11.2, A trace amount of hypochlorous acid. Sodium chlorate is added, and then the reaction is continued while maintaining the pH at 10.5 to 11.5, preferably 10.8 to 11.2. After the reaction is completed, the pH is 10.5 to 11.5, preferably It is characterized by being maintained through 10.8 to 11.2, subjected to residual chlorine removal treatment, and then subjected to water washing, dehydration, drying, and pulverization.

According to the bleached starch of the present invention according to an embodiment of the present invention, chlorine gas generated from the remaining sodium hypochlorite is minimized, and as a result, the chlorine odor remaining in the starch can be significantly reduced. it can. In addition, when the pH is near neutral or lower, the reduction of starch viscosity by sodium hypochlorite is promoted, but in the present invention, sodium hypochlorite continues to react or remains in a trace amount. Under the circumstances, the pH is not reduced to about neutral or lower, so that the effect of thickening is not impaired as compared with the conventional method, and an improved bleached starch and a method for producing the same can be provided.

The starch as used in the present invention is at least one kind of starch selected from corn starch, high amylose corn starch, waxy corn starch, sago starch, mung bean starch, wheat starch, rice starch, potato starch, sweet potato starch, tapioca starch and the like. means. Among these, tapioca starch, corn starch, waxy corn starch, and potato starch are preferred as inexpensive starches that have high viscosity and are distributed in large quantities in the market.

Generally starch bleaching is at least selected from peracetic acid, hydrogen peroxide, sodium hypochlorite, calcium hypochlorite, sodium chlorite, sulfur dioxide, sulfites, potassium permanganate, ammonium persulfate. This is done using a kind of bleach. However, among these bleaching agents, sodium hypochlorite has the highest thickening effect and is inexpensive, so the present invention is characterized by using sodium hypochlorite. On the other hand, untreated starch as used in the field of this invention means the starch which is not processed using the said bleaching agent.

The processed starch as used in the field of this invention means what changed the physical property and property of starch by chemical and / or physical processing. In chemical processing, as representative types, phosphoric acid crosslinking, acetylated adipic acid crosslinking, aldehyde crosslinking, acrolein crosslinking, epichlorohydrin crosslinking, graft polymerization, acetylation, phosphorylation, formication, fatty acidization, sulfation, Examples include hydroxyethylation, hydroxyalkylation, hydroxypropylation, carboxylmethylation, cyanoethylation, methylation, cationization, octenyl succination and the like. Typical examples of physical processing include pregelatinization, wet heat treatment, fat and oil processing, enzyme treatment, acid treatment, alkali treatment, hot water treatment, ball mill treatment, and high pressure treatment. In the present invention, these modified starches can be used as a raw material for the purpose of combining the properties of the starch obtained by the above-mentioned processing with the strengthening of the grain structure of the starch by sodium hypochlorite. For example, combining processing methods that do not have the effect of strengthening the grain structure of starch, such as acetylation, hydroxypropylation, and octenyl succination, and strengthening the grain structure with sodium hypochlorite is significant in improving the physical properties of processed starch. It is. In addition, combining phosphoric acid crosslinking and acetylated adipic acid crosslinking, such as processing methods aimed at strengthening the grain structure of starch grains, and strengthening of grain structure with sodium hypochlorite, It is effective in reducing the crosslinking agent used for acetylated adipic acid crosslinking and fine-tuning the degree of grain structure strengthening. Therefore, the production method of the present invention may be included in the production process of the modified starch.

The carboxyl group content in the present invention indicates a carboxyl group in starch introduced by a reaction using sodium hypochlorite, and the degree of processing with sodium hypochlorite is determined using this value. can do. In the present invention, by setting the carboxyl group content in the starch to less than 0.1% by weight, the thickening can be increased and the residual chlorine odor can be reduced as compared with the untreated starch. If the carboxyl group content is 0.1% or more, viscosity reduction by sodium hypochlorite is promoted, so that thickening cannot be obtained, and further hypochlorous acid in the starch suspension in the reaction. Since the amount of sodium becomes excessive, the chlorine odor tends to remain.

The carboxyl group content is quantified by the following method. After adding 50 ml of 0.1N hydrochloric acid to a starch sample having a dry matter weight of 5.0 g and stirring for 30 minutes, suction filtration is performed using a glass filter (17G-4). Washing with distilled water is continued until the filtrate does not exhibit chloride reaction. 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 to gel, and further heated for 15 minutes, then 3 drops of phenolphthalein indicator are added and immediately colored with 0.1N sodium hydroxide solution. Titrate until. In the blank test, 50 ml of distilled water is added to a starch sample having a dry matter weight of 5.0 g, stirred for 30 minutes, then suction filtered using a glass filter (17G-4), 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 to gel, and further heated for 15 minutes. Then, 3 drops of phenolphthalein indicator is added and immediately colored with 0.1N sodium hydroxide solution. Titrate until The carboxyl group content is calculated using the following formula.
Carboxyl group content (% by weight) = (A−B) × F × 0.45 / 5
A: Sample titration (ml)
B: Blank test titration (ml)
F: 0.1N sodium hydroxide titer

The amount of sodium hypochlorite used in the present invention is 50 to 4000 ppm, preferably 100 to 2000 ppm as effective chlorine based on the weight of the starch dry product. However, the optimum amount of sodium hypochlorite added to obtain a higher viscosity than that of untreated starch varies depending on the type of raw starch. For example, when the raw starch is tapioca starch, the optimum amount of sodium hypochlorite is 200 to 1000 ppm, preferably 300 to 700 ppm. When the raw starch is corn starch, the optimum amount of sodium hypochlorite added is 200 to 2000 ppm, preferably 500 to 1000 ppm. When the raw starch is waxy corn starch, the optimum amount of sodium hypochlorite added is 200 to 4000 ppm, preferably 500 to 2000 ppm. When the raw material starch is potato starch, the optimum amount of sodium hypochlorite added is 50 to 1000 ppm, preferably 100 to 500 ppm.

The effective chlorine of sodium hypochlorite is quantified by the following method. About 10 g of sodium hypochlorite sample is precisely weighed and transferred to a 200 ml volumetric flask, and then distilled water is added to make a 200 ml sample solution. Take 10 ml of this sample solution in an Erlenmeyer flask with a 200 ml stopper, add 20 ml of 10% potassium iodide solution and 20 ml of 30% sulfuric acid, and mix. This is left to stand in the dark for 5 minutes, and then titrated with 0.05N sodium thiosulfate until colorless. In the blank test, the same operation is performed using 10 ml of distilled water as the sample solution. Effective chlorine is calculated using the following formula.
Effective chlorine (% by weight) = (A−B) × F × 3.55 / S
A: Sample titration (ml)
B: Blank test titration (ml)
F: Potency of 0.05N sodium thiosulfate
S: Sample weight (g)

The reaction after the addition of sodium hypochlorite in the present invention is carried out while maintaining pH 10.5 to 11.5, preferably pH 10.8 to 11.2. The maintenance of the pH is achieved by appropriately adding an alkali agent such as sodium hydroxide or calcium carbonate, and the alkali agent may be either solid or solution. If the pH is not maintained, the pH gradually decreases due to the reaction of sodium hypochlorite. When the pH reaches near neutral or lower, the viscosity of starch is reduced by sodium hypochlorite, and the generation of chlorine gas is further promoted. Therefore, keeping the pH during the reaction highly alkaline is very important from the viewpoint of the physical properties and odor of starch. However, if the pH is maintained at 11.5 or higher, starch swelling occurs during the reaction, and the viscosity of the starch suspension during the reaction increases, which may cause uneven reaction and clogging in the process. Absent.

The reaction temperature after addition of sodium hypochlorite in the present invention is 15 to 55 ° C, preferably 30 to 45 ° C. When the reaction temperature is 15 ° C. or lower, the reaction efficiency is extremely lowered, and when the reaction temperature is 55 ° C. or higher, the viscosity of the starch suspension during the reaction becomes high, which may cause uneven reaction and clogging in the process. .

The reaction time after addition of sodium hypochlorite in the present invention is 15 to 180 minutes, preferably 30 to 90 minutes. The improvement in the thickening effect by sodium hypochlorite can be obtained by a relatively short reaction, but the reaction tends to be non-uniform in the reaction for 15 minutes or less, and the starch is low in the reaction for 150 minutes or more. This is not preferable because of viscosity increase.

In the present invention, the residual chlorine removal treatment is performed by adding a reducing agent such as sodium bisulfite, sodium sulfite, sodium pyrosulfite, sodium ascorbate to the starch suspension during the reaction in order to terminate the reaction with sodium hypochlorite. It means adding. The reducing agent may be a solid or a solution. Moreover, the addition amount of a reducing agent can be suitably adjusted according to the addition amount of sodium hypochlorite and the amount of residual chlorine remaining. The presence or absence of residual chlorine remaining in the starch suspension can be qualitatively confirmed by the KI check method.

The KI check method is the following method. 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 solution are added to the solution 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.

Residual chlorine removal treatment with a reducing agent can be achieved in a very short time, but even if the reaction time is extended, the physical properties and odor of starch are not affected at all. is not. Further, as described above, the residual chlorine removal treatment is continuously performed at a pH of 10.5 to 11.5, preferably at a pH of 10.8 to 11.2. It becomes possible to significantly reduce the residual chlorine odor.

By using the bleached starch obtained by the present invention for foods, it is possible to achieve an increase and stabilization of thickening, viscoelasticity and shape retention after heating and cooking. Examples of its use include sauces, sauces, dressings, fillings, marine products, dim sums, noodles, Japanese and Western confectionery, and the like.

The details of the present invention will be described below by showing examples. However, the present invention can be implemented in many different modes, and should not be construed as being limited to the description of the examples shown below. Absent.

Example 1
Water was added to 100 g of untreated tapioca starch to prepare a starch suspension having a solid content of 38%. Next, the pH is adjusted to 11.0 using 3% sodium hydroxide, 500 ppm of sodium hypochlorite is added as effective chlorine to the dry starch weight, and the pH is maintained at 11.0 using 3% sodium hydroxide. The reaction was carried out at 34 ° C. for 60 minutes. Thereafter, 250 ppm of sodium pyrosulfite was added with respect to the dry weight of starch, reacted at 34 ° C. for 30 minutes while maintaining the pH at 11.0 using 3% sodium hydroxide, and then at pH 5.5 using 9% hydrochloric acid. Adjusted. Subsequently, this starch suspension was washed twice with 5 times the amount of water, and the resulting starch cake was dried at 40 ° C. for 7 hours to adjust the water content to 8 to 15%. This was pulverized with a mixer and passed through 80 mesh to make a starch sample.

(Comparative Example 1)
Comparative Examples 1-1 and 8 were prepared using 3% sodium hydroxide and 9% hydrochloric acid and maintaining the reaction pH after addition of sodium hypochlorite and the reaction pH after addition of sodium pyrosulfite at 5.5. What was kept at 0 was used as a starch sample of Comparative Example 1-3. Other operations were the same as in Example 1.

(Comparative Example 2)
The reaction pH after addition of sodium hypochlorite was maintained at 11.0, and the reaction pH after addition of sodium pyrosulfite was maintained at 5.5, which was maintained at Comparative Example 2-1 and 8.0. The starch sample of Comparative Example 2-2 was used. Other operations were the same as in Example 1.

(Comparative Example 3)
Without adding sodium hypochlorite, other operations were performed in the same manner as in Example 1 to obtain a starch sample.

(Test Example 1)
Distilled water was added to the starch sample to prepare 30 g of a starch suspension with an appropriately adjusted concentration, and the viscosity after heating was measured using Rapid Visco Analyzer-4 (manufactured by NEWPORT SCIENTIFIC PTY LTD). The measurement conditions are as follows. The final viscosity (50 ° C.) of the viscosity chart obtained by the measurement is shown in Tables 1 to 4 as the paste viscosity of the starch sample.
Temperature setting: After holding at 50 ° C. for 60 seconds, the temperature is raised to 95 ° C. at 0.2 ° C./second and held at 95 ° C. for 150 seconds. Then, it cools to 50 degreeC at 0.2 degreeC / second, and hold | maintains at 50 degreeC for 120 second.
Paddle rotation speed: 160rpm

(Test Example 2)
A 10 g starch sample was placed in a 200 ml tall beaker, and the strength of the chlorine odor of starch was sensorially evaluated while stirring with a plastic rod. Next, 15 ml of distilled water was added to this starch sample and stirred sufficiently, and the strength and weakness of the chlorine odor of the starch suspension was sensorially evaluated while stirring. Furthermore, boiling distilled water was added to this starch suspension sample to prepare 100 ml of starch paste, and the intensity of chlorine odor was sensoryly evaluated while stirring. The sensory evaluation of odor was scored by a 6-step evaluation of 0 to 5, and the higher the score, the stronger the chlorine odor. The obtained results are shown in Tables 1 to 4.

From Table 1, Example 1 confirmed that the paste viscosity was higher than Comparative Examples 1 to 3, and the chlorine odor was reduced, and the intended effect of the present invention was obtained. The carboxyl group content was less than 0.1% in all cases.

(Example 2)
Water was added to 100 g of untreated corn starch to prepare a starch suspension having a solid content of 38%. Next, the pH is adjusted to 11.0 using 3% sodium hydroxide, 1000 ppm of sodium hypochlorite is added as effective chlorine to the dry weight of the starch, and the pH is maintained at 11.0 using 3% sodium hydroxide. The reaction was carried out at 34 ° C. for 60 minutes. Thereafter, 500 ppm of sodium pyrosulfite was added to the dry weight of the starch, and the mixture was reacted at 34 ° C. for 30 minutes while maintaining the pH at 11.0 using 3% sodium hydroxide, and then at pH 5.5 using 9% hydrochloric acid. Adjusted. Subsequently, this starch suspension was washed twice with 5 times the amount of water, and the resulting starch cake was dried at 40 ° C. for 7 hours to adjust the water content to 8 to 15%. This was pulverized with a mixer and passed through 80 mesh to make a starch sample.

(Comparative Example 4)
The reaction pH after addition of sodium hypochlorite was maintained at 11.0, and the reaction pH after addition of sodium pyrosulfite was maintained at 5.5, which was maintained at Comparative Examples 4-1 and 8.0. The starch sample of Comparative Example 4-2 was used. Other operations were the same as in Example 2.

(Comparative Example 5)
Without adding sodium hypochlorite, other operations were performed in the same manner as in Example 2 to obtain starch samples.

From Table 2, it was confirmed that Example 2 had a higher paste viscosity than Comparative Examples 4 and 5 and had a reduced chlorine odor, so that the intended effect of the present invention was obtained. The carboxyl group content was less than 0.1% in all cases.

(Example 3)
Using an untreated waxy corn starch as a raw material, a starch sample was obtained in the same manner as in Example 2.

(Comparative Example 6)
The reaction pH after addition of sodium hypochlorite was maintained at 11.0, and the reaction pH after addition of sodium pyrosulfite was maintained at 5.5, which was maintained at Comparative Examples 6-1 and 8.0. The starch sample of Comparative Example 6-2 was used. Other operations were the same as in Example 1.

(Comparative Example 7)
A starch sample was obtained in the same manner as in Example 3 except that sodium hypochlorite was not added.

From Table 3, Example 3 confirmed that the paste viscosity was higher than Comparative Examples 6 and 7, and the chlorine odor was reduced, so that the intended effect of the present invention was obtained. The carboxyl group content was less than 0.1% in all cases.

Example 4
Water was added to 100 g of untreated potato starch to prepare a starch suspension having a solid content of 38%. Next, the pH is adjusted to 11.0 using 3% sodium hydroxide, 250 ppm of sodium hypochlorite is added as effective chlorine to the dry weight of the starch, and the pH is maintained at 11.0 using 3% sodium hydroxide. The reaction was carried out at 34 ° C. for 60 minutes. Thereafter, 125 ppm of sodium pyrosulfite was added with respect to the dry weight of the starch, reacted at 34 ° C. for 30 minutes while maintaining the pH at 11.0 using 3% sodium hydroxide, and then at pH 5.5 using 9% hydrochloric acid. Adjusted. Subsequently, this starch suspension was washed twice with 5 times the amount of water, and the resulting starch cake was dried at 40 ° C. for 7 hours to adjust the water content to 8 to 15%. This was pulverized with a mixer and passed through 80 mesh to make a starch sample.

(Comparative Example 8)
The reaction pH after addition of sodium hypochlorite was maintained at 11.0, and the reaction pH after addition of sodium pyrosulfite was maintained at 5.5, which was maintained at Comparative Examples 8-1 and 8.0. The starch sample of Comparative Example 8-2 was used. Other operations were the same as in Example 1.

(Comparative Example 9)
A starch sample was obtained in the same manner as in Example 3 except that sodium hypochlorite was not added.

From Table 4, it was confirmed that Example 4 has a higher paste viscosity than Comparative Examples 8 and 9, and has a reduced chlorine odor, so that the intended effect of the present invention can be obtained. The carboxyl group content was less than 0.1% in all cases.

Claims (7)

After adding sodium hypochlorite to the starch suspension obtained by adding water to untreated starch and reacting at pH 10.5 to 11.5, the residual chlorine removal treatment of the starch suspension is pH 10.5 to A starch produced by performing at 11.5, wherein the starch has a carboxyl group content of less than 0.1% by weight and a paste viscosity higher than that of untreated starch. The starch according to claim 1, wherein the amount of sodium hypochlorite added is 50 to 4000 ppm as effective chlorine based on the weight of the dried starch. The starch according to claim 2, wherein the untreated starch is tapioca starch, and the amount of the sodium hypochlorite added is 200 to 1000 ppm as effective chlorine with respect to the weight of the dried starch. The starch according to claim 2, wherein the untreated starch is corn starch, and the amount of the sodium hypochlorite added is 200 to 2000 ppm as effective chlorine with respect to the weight of the dried starch. The starch according to claim 2, wherein the untreated starch is waxy corn starch, and the amount of the sodium hypochlorite added is 200 to 4000 ppm as effective chlorine with respect to the weight of the dried starch. The starch according to claim 2, wherein the untreated starch is potato starch, and the amount of sodium hypochlorite added is 50 to 1000 ppm as effective chlorine with respect to the weight of the dried starch. A food comprising the starch according to any one of claims 1 to 6.