JP3365656B2 - Method for producing modified starch - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention is to modify the polymer physical properties of various starches (the property that when the suspension is heated, the starch granules swell to a large extent to form a highly viscous paste solution). The present invention relates to a method for producing starch, which has a significantly large water-absorption / swelling property at room temperature (25 ° C.) and whose swelling degree changes little even when the temperature is increased.
Disperse and suspend in an alcohol solution such as 60% by volume of ethanol and heat it in a sealed state for at least 10
The present invention relates to a method for producing a modified starch by collecting the starch after drying at 0 ° C. or higher, drying and pulverizing the starch.

[0002]

2. Description of the Related Art Starch is most used for hydrolysis, and its utilization ratio reaches about 60% of the whole, but there is a direct method of utilizing its polymer property. In the case of the latter use, when starch is heated with water, the granules swell significantly and become a paste solution. At this time, the viscosity of the paste solution, the gelatinizing property, the stability of the sol, the sol-gel transition, and the gel. Properties such as the properties of are particularly important. These properties vary considerably depending on the type of starch, and in the industry, starch has been used properly according to each application.

A practical paste solution is one in which a part of the starch is dissolved from around the gelatinization temperature during heating of the starch suspension to form a solution, and most of the starch granules are largely swollen while maintaining the original shape,
It can be said that particles that have collapsed to the point where swollen particles do not retain their original shape are dispersed at various ratios.
The properties of such a paste solution are not only characteristic but also sometimes cause various obstacles in industrial use. For this reason, so-called modified starches such as derivatives have been used by various chemical methods to improve their physical properties. In particular,
Among the physical properties, the swelling of starch granules and the high viscosity of starch paste are characteristic and disadvantageous, so low-viscosity starch is required in the industry, and actually oxidized starch, esterified starch, etc. are produced. Has been done.

However, in terms of food processing, the use of these modified starches is not preferable from the viewpoints of food hygiene and taste. Therefore, the industry has found industrial conditions for modifying starch by heat treatment as a means for improving it. A patent application has been filed (Patent application No. 253029, 1990).
In this method, in principle, starch in equilibrium moisture state is treated with a humidity of 10
This is a method of heating to a high temperature of 100 ° C. or higher in a 0% atmosphere. By adopting a reduced pressure / pressurization method, it is possible to industrially mass-produce, and it is possible to produce modified starch of excellent quality. is there. In this method, the degree of modification of starch differs depending on the heating temperature, and therefore its adjustment is important, and fine process control is required to obtain a uniform product.

[0005]

What is desired in the method for producing a modified starch is that the properties of the starch such as swelling property, gelatinization property, viscosity, heat stability and solubility can be continuously changed. Further, it is preferable that the change in grain shape is small, and the range of these modifications is as wide as possible, the degree of which can be easily controlled, and the modification can be made as uniform as possible. Furthermore, it is also desired that the treated starch be easily collected and dried into powder.

In the present invention, starch is dispersed / suspended in a mixed solution of water and an alcohol solvent such as ethanol and heat-treated to change the above-mentioned various properties of starch, particularly swelling property. Found to undergo significant changes,
It has been found that the degree of modification of starch can be easily controlled by combining the water content and the heating temperature at this time. Also,
In these treatments, the starch granules show almost no change in appearance, and separation, drying and pulverization after the treatment are easy. The purpose of the present invention is to set the temperature at room temperature (25
The purpose is to prepare a modified starch whose swelling property at (.degree. C.) becomes extremely large and whose swelling degree does not change so much even when the temperature is raised.

[0007]

In order to achieve the above object, the modified starch of the present invention is prepared by dispersing and suspending starch in an alcohol solution having a water content of 25 to 60% by volume to prepare 100 parts thereof.
It is produced by heating to ℃ to 130 ℃ .

As the starch used in the present invention, various starches and cereal powders such as wheat flour can be used, but practically,
It is suitable to use cornstarch, which is the most mass produced, readily available and inexpensive. In the present invention, the degree of starch denaturation was determined by measuring the degree of starch swelling and the solubility during swelling at different temperatures.
The starch swelling degree and the solubility were performed according to the method of Kainuma.

That is, 0.25 to 0.50 g as an anhydride
The sample of 1 was precisely weighed in a centrifuge tube, 10 ml of water was added thereto, and the mixture was heated at each temperature of 25 to 100 ° C. for 1 hour, then immediately centrifuged at 4500 rpm for 30 minutes, and the supernatant was removed to remove the precipitate. Was measured, the total amount of sugar in the supernatant at that time was measured by the phenol-sulfuric acid method to calculate the amount of dissolution, and the swelling degree and solubility of starch were calculated from these values. Raw starch and almost unmodified starch swell significantly at high temperatures, and the water used is completely absorbed by the starch granules, and the supernatant liquid disappears, making it impossible to measure the solubility. It was set to 25 g.

According to this measurement condition, unmodified raw starch which has not been modified has a swelling degree of 1 to 2% at 25 ° C., but when it exceeds 70 ° C., it rapidly swells as the temperature rises to 100%.
The degree of swelling at 25 ° C is about 25%, which is more than 10 times the value at 25 ° C. The solubility is almost insoluble at 25 ° C.
%, But it also rises from 70 ° C., and at 100 ° C., the solubility is 20% or more, which means that the solubility is considerably high. Based on this, the degree of starch modification was determined.

The dyeability of starch granules was also compared. That is, a small amount of a sample was placed in a centrifuge tube, and about 0.5 ml of a 1% safranine T (basic red dye) solution was added to and mixed with the centrifuge tube, and the mixture was allowed to stand for about 5 minutes. After centrifuging it and discarding the supernatant, the precipitate was washed 3 times with water to remove excess dye, and then sample starch dyed in red was placed on a deck glass and a drop of 1% Direct Sky Blue 5B (direct blue color) (Dye) was added and mixed, and the mixture was observed under a microscope to read the ratio of starch granules dyed in blue. At the same time, changes in the size and shape of the starch granules were observed. Moreover, the measurement with a differential scanning calorimeter and a viscometer was also performed appropriately.

In the present invention, the most important points are the mixing ratio of water and alcohols and the heating temperature suitable for modifying starch. The alcohol used in the present invention is most preferably ethanol that satisfies the safety and taste conditions from the viewpoint of producing a modified starch to be used for food. However, propyl alcohol, isopropyl alcohol and the like can also be used.
The mixing ratio of these alcohols and water is an important factor constituting the present invention. In the case of ethanol, if the mixing ratio with water is 25% by volume or less, there is almost no denaturing effect, and if it is 60% by volume or more, the starch swells excessively and the particle shape is broken, which is not preferable. The heating temperature has different effects on the degree of denaturation depending on the proportion of water. When the water content is 50% by volume or more, it is mildly modified even at 80 ° C, but when the water content is 30% by volume or less, substantial modification is not observed unless it is heated to 100 ° C or more. Preferably, it is carried out by heating at a heating temperature of 110 to 130 ° C. for about 10 to 20 minutes with a water content of 34 to 50% by volume.

The starch reaction vessel used in the present invention is capable of heating the contents by indirect heating, and is a closed type pressure heating system equipped with a stirrer capable of preventing the precipitation of starch. Is possible. In this reaction vessel, starch is dispersed in a water-alcohol solution and reacted by heating, and after a certain period of time, cooled and treated starch is collected by filtration, and dried by an appropriate dryer to produce modified starch. It In the case of small quantity production, put it in a suitable container.
An ethanol solution containing 60% by volume of water was added, the starch was dispersed therein, and the container was tightly stoppered. While shaking the container in boiling water, the inside of the container was slightly lower than the boiling point of ethanol to about 70 to 75 ° C. It is sufficient to heat until it is heated, and immediately put it in a fully preheated autoclave and heat it under pressure. afterwards,
The starch may be collected by filtration or centrifugation and dried by a method such as washing with ethanol, acetone or ether.

When the heating temperature is increased to 130 ° C., the swelling degree at 25 ° C. becomes 6 even when the water content is 30%, and the swelling degree at 100 ° C. becomes about 2-3 times. When the heating temperature is 120 ° C. and the heating time is 20 minutes, the proportion of water in the alcohol solution is
Below 20% by volume, the degree of swelling is virtually unchanged from that of raw starch, and that at 100 ° C. is about 10 to 13 times the degree of swelling at room temperature. However, the measurement result of the differential scanning calorimeter shows that the endothermic amount at the time of gelatinization is about 10 to 30% lower than that of raw starch. Also, regarding the viscosity, the maximum viscosity reaching temperature is about 10 ° C.
It becomes lower and is clearly under the change. The change in the degree of swelling of starch changes from the point where the water content exceeds 25% by volume, and the degree of swelling at room temperature increases when it exceeds 34%, but conversely the degree of swelling at high temperature is 1.
It is only about 2 to several times, and the difference in the degree of swelling with temperature is reduced. Moreover, this tendency becomes larger as the water content in the alcohol solution becomes higher, and the swelling degree at 25 ° C. becomes about 4 to 10 at a water content of 34 to 60% by volume. This means that 1 g of starch absorbs 3 to 9 g of water and swells, and this property can be sufficiently utilized as a disintegrant during tablet production. On the other hand, 100
1. When the degree of swelling when heated to ℃ is only 25 ℃.
I also found that it was only 5 to 2.3 times.

In terms of solubility of starch, untreated ones at room temperature (25 ° C.) are less than 0.1% and hardly dissolve, but the solubility rapidly increases from 70 ° C. (see Table 2). Water content in raw starch and alcohol solution is 2
Starch treated with 0% by volume or less has a solubility of about 2 at 100 ° C.
Although it was around 5%, the solubility at high temperature tended to decrease on the contrary when treated with a water content of 25% by volume or more.
The blue value of the starch eluted at a high temperature due to the iodine color reaction was high, which was about 2.8 times that of the precipitated starch and slightly less than twice that of the original starch.

The water content in the alcohol solution is 30.
If the volume% is exceeded, α-at 40 ° C even at 120 ° C heat treatment
The initial rate of starch digestion by amylase tended to rapidly increase in proportion to the water content. Moisture content is 40-6
At 0% by volume, the starch granules swell and grow larger,
It still retains its original shape and most starches become dyed. From these, it is inferred that the starch granules had gaps. When the water content is 70% by volume, it swells too much and the disintegration of the grains is recognized, and it becomes like a partially gelatinized starch.
In this case, drying of the treated starch becomes somewhat difficult. From the point of dry powdering of the treated starch, the operation is easier when the water content is 50% by volume or less.

As described above, the degree of modification of starch is
If the treatment temperature is constant, it continuously changes depending on the water content of the alcohol solution. Also, keep the water content constant,
The degree of denaturation also changes continuously by changing the treatment temperature. The apparent denaturation of the swelling property was observed when the volume ratio of ethanol and water was about 75:25 and the water content increased. Considering the low degree of swelling when heated to a high temperature, the high water absorption and high swelling at room temperature, and the ease of post-treatment, the heating temperature is 110 to 120.
It is preferable that the moisture content is 30 to 50% by volume at 20 ° C. for 20 minutes.

In the present invention, when the starch suspension is prepared, the ratio of the alcohol solution to the starch used is preferably 3 to 5 times the volume. However, when the water content in the alcohol solution is low (25 to 35% by volume), it is possible to use double the volume of starch. Assuming that the alcohol is used at 5 times the volume of starch and the water content is 40% by volume, the ratio of starch: water: ethanol is 1: 2: 3.

[0019]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited thereto. Example 1 First, commercially available corn starch was dispersed in a water-ethanol mixed solution, and heat-treated at 120 ° C. for 20 minutes in an autoclave. Next, 20 g of commercially available cornstarch was placed in an Erlenmeyer flask with a ground stopper (300 ml), and 100 ml of a mixed solution of ethanol and water having a volume ratio shown in Table 1 was added thereto, and the mixture was shaken and stirred to obtain a dispersion liquid. This was heated while shaking in a boiling water bath, and when the contents reached about 70 ° C, the contents were placed in a preheated autoclave, sealed, and heated under pressure at 120 ° C for 20 minutes. Then, it was immediately cooled and centrifuged, and the precipitate was washed with absolute ethanol and further washed with ether. This was vacuum dried at 40 ° C. to obtain dry starch. Table 1 shows the modification degree of the treated starch under the influence of the water content in the water-ethanol binary system.

[0020]

[Table 1]

As is clear from Table 1, the starch treated with ethanol with a water content of 0 to 20% by volume was almost the same as the untreated raw starch. Also, when the water content was 70% by volume, the starch granules clearly disintegrated, swelled well even at low temperature, and became in a state similar to that of partially gelatinized starch, and the solubility at 100 ° C. was almost the same as that of raw starch. Further, even when the water content is 30 to 60% by volume, the degree of swelling at a low temperature is obviously large, and particularly at 40 to 60% by volume, the degree of swelling at 25 ° C. is about 7 to 10 times, and conversely, it is not so high even at high temperature. The degree of swelling did not change. This shows the feature of the modified starch production method of the present invention.

The above-mentioned ethanol: water volume ratio is 6: 4.
Table 2 shows the denaturation degree (swelling degree and solubility) of starch at 120 ° C. for 20 minutes at each temperature.

[0023]

Example 2 A plastic bottle with a stopper (2000 ml) was mixed with a mixed solution of ethanol and water in a volume ratio shown in Table 3 at 1,000 times each.
The temperature of the contents was adjusted to about 70 ° C. by putting ml in a bath at about 90 ° C. Immediately after, 300 g of commercially available cornstarch was dispersed, stoppered and heated while shaking in the same bath for a while, steam was generated in advance to raise the room temperature, and then placed in an autoclave and sealed.
It was heated under pressure at 120 ° C. for 0 minutes. Then, immediately after cooling and filtering, the obtained wet starch cake was washed with an ethanol solution. Then, squeeze and dehydrate, then spread thinly and 45
Dried starch was obtained by air-drying at ℃. Table 3 shows the modification degree of these treated starches of the water-ethanol binary system (water content 30 to 36% by volume).

[0025]

As is clear from Table 3, the degree of swelling at 100 ° C. does not differ greatly when the water content is 30 to 36% by volume, but the degree of swelling at 25 ° C. tends to increase from 34% as the volume ratio increases. Indicated. What is considered in this Example 2 together with Example 1 is that it is possible to carry out the desired starch by changing the water content according to the purpose of modification.

[0027]

The modified starch of the present invention is produced by dispersing and suspending it in an alcohol solution having a specific water content and heating it to a specific temperature. The desired modified starch is easily obtained. In particular, it is possible to easily prepare a modified starch that has a large degree of swelling at room temperature (25 ° C.) and that does not change so much even when the temperature is increased.

Claims (3)

(57) [Claims] 1. Starch is dispersed / suspended in an alcohol solution having a water content of 25 to 60% by volume, and this is placed at 100 ° C. to 13 ° C.
A method for producing a modified starch, characterized in that a polymer physical property is modified by heating at 0 ° C. 2. The method for producing a modified starch according to claim 1, wherein the alcohol is ethanol. 3. The method for producing modified starch according to claim 1, wherein the treatment is carried out in an alcohol solution having a water content of 34 to 50% by volume at a heating temperature of 110 to 130 ° C.