JPH0446901A - Production of amylose - Google Patents

Abstract

PURPOSE:To obtain highly pure amylose simply and continuously without using any precipitant or enzyme by adding the step of filtering a suspension containing amylose and amylopectin and obtained by treating starch with water at a specified temperature through a specified filter membrane and separating the amylose into the filtrate. CONSTITUTION:This process comprises the step of filtering a suspension containing amylose and amylopectin and obtained by treating starch with water at 40 deg.C or above through a filter membrane, desirably a ceramic filter membrane of a mean pore diameter of 0.01-0.1mum preferably by the cross flow process to separate the amylose into the filtrate.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for easily producing amylose from starch.

[Conventional technology]

Environmental pollution caused by synthetic polymers has become a problem, and biodegradable polymers are in demand, and amylose is attracting attention as one of the natural biodegradable polymers that make up starch.

Conventionally, the method for separating and producing amylose from starch involves treating starch in hot water at 50 to 80°C to dissolve amylose, and adding n-butanol, nitroparaffin, thymol, etc. to the resulting mixture. A known method is to generate an insoluble complex with amylose, precipitate and separate the complex, and then separate amylose from the complex.

In addition, a method has been proposed in which amylopectin in starch is converted to short-chain amylose using α-1,6-glucosidase, and then natural amylose is separated using the difference in molecular weight from natural long-chain amylose. (Tokuko Sho 54-214
Publication No. 20).

[Problem to be solved by the invention]

In the method of precipitating and separating the complex with n-butanol, etc., additives such as n-butanol tend to remain as impurities in the obtained amylose, and amylopectin also tends to adsorb to the precipitate and remain as an impurity. Therefore, there are problems with the purity of the amylose obtained, and addition of n-butanol, etc. and separation from the complex are necessary, and in order to efficiently separate the precipitate, a centrifuge is required. It has the disadvantage that the operation is complicated because of the need to use it.

In addition, the method of separating amylopectin after reducing its molecular weight with α-1,6-gelcoditase requires a treatment operation using this enzyme. Since this method uses fractional precipitation and a precipitant such as n-butanol, it has the same drawbacks as the above-mentioned method.

Therefore, an object of the present invention is to provide a method for producing amylose that does not use any precipitants or enzymes that cause a decrease in the purity of amylose, and that allows highly pure amylose to be obtained with simple operations.

[Means to solve the problem]

The present inventors efficiently extract amylose from a suspension with amylopectin by using a filtration membrane with a certain pore size.
It has been found that separation can be achieved with high purity.

That is, in the present invention, a suspension containing amylose and amylopectin obtained by treating starch in water at 40° C. or higher is filtered through a filtration membrane with an average pore size of 0.01 to 0.1 μm,
The present invention provides a method for producing amylose, which includes a step of separating amylose into a filtrate.

In the method of the invention, starch is treated in water at a temperature of 40° C. or higher. A boiling state may be used as long as the temperature is 40°C or higher. A temperature of 60 to 100"C is appropriate from the standpoint of thermal energy consumption efficiency, operational practicality, etc. By this treatment in water, amylopectin swells and amylose is dissolved in water. This amylose and amylopectin-containing The concentration of the suspension when the suspension is subjected to filtration is preferably about 0.1 to IO%, for example.

As the filtration membrane used for filtration, various materials can be used, such as ceramic, carbon,
Examples include those made of materials such as various sintered metals. Among these, particularly good amylose permeability,
Ceramic membranes are preferred because they are advantageous in terms of heat resistance, microbial resistance, and bactericidal properties. Examples of the material for the ceramic film include metal oxides such as zirconia, alumina, and silica, and their composites, nitrides, and carbides.

Furthermore, as the filtration method used in the method of the present invention, a method that produces less dynamic membranes that clog the pores of the filtration membrane is desirable. Such filtration methods include cross-flow filtration, methods using filters equipped with mechanical cleaning means to prevent dynamic membrane formation, and filtration with intermittent back-pressure washing. Examples include methods.

When filtering by cross-flow filtration method, the pressure difference between the inside and outside of the filtration membrane is preferably 2 kgf/cm" or less, and I kgf/cm" or less.
cm" or less. Also, the flow velocity of the suspension supplied to the filtration membrane at the membrane surface is a Reynolds number of 3.000 or more, preferably 5.000 or more, and more preferably 10.000 or more. The flow rate is more preferably 0.5 m/sec or more, preferably 1.5 m/s, although it depends on the size of the filter etc.
Equivalent to ec or higher.

Under these favorable conditions, the formation of a dynamic membrane due to amylose and amylopectin on the filtration layer due to the turbulent flow effect is prevented, so the amylose permeability of the filtration membrane does not decrease and can be maintained continuously for a long period of time. It is possible to perform a separation.

There are no particular restrictions on the starch used as a raw material in the method of the present invention, such as corn starch).
, potato, sweet potato, wheat, starch such as mackerel, amylose starch, etc.

〔Example〕

Hereinafter, the method of the present invention will be specifically explained with reference to Examples.

Example 1 Amylose was separated and produced from corn starch using a filter whose structure is schematically shown in FIG. 1 and an apparatus whose structure is schematically shown in FIG. 2.

The filter 1 in Fig. 1 is made of alumina and has an outer diameter of 5 mm and a length of 5 mm.
0cm, surface area 74.5cm', average pore diameter 0.05μ
m ceramic tube closed at one end 2 with an inner diameter of 7
．． Built into a 5a+m stainless steel cylinder 3,
The other end 4 of the cylinder 3 is closed with an O-ring or the like.

The stock solution is supplied from the direction of arrow 5, and the permeate that has passed through the alumina tube 2, which is a filtration membrane, is separated as shown by arrow 6.

The unpermeable portion of the stock solution is refluxed.

Cornstarch was boiled in distilled water to prepare a suspension with a concentration of 1% by weight, and 2 dm' of this suspension was placed in a heated sample liquid tank 7 as shown in Figure 2 and kept at a predetermined temperature. . The sample liquid was pressurized into the filter 1 from the tank 7 by the pump 9, 0.1% permeated into the ceramic tube and separated into the container 8, and the rest was refluxed to the tank 7. The sample liquid volume in tank 7 was maintained at 2 dm' by injecting distilled water every 15 minutes.

The above operation is performed based on the pressure difference between the inside and outside of the ceramic tube 2, the linear velocity of the sample liquid on the surface of the ceramic filtration membrane, and the filter l.
The permeation flux, amylose concentration, etc. of the permeate were measured by varying the temperature of the sample liquid injected into the tube.

(A) Temperature of sample liquid: 50℃ 1 linear velocity: 3.0 m/s
ee, and changes in the permeate flux and amylose concentration over time were measured while varying the differential pressure. The results are shown in Figure 3. It can be seen that the smaller the differential pressure, the higher the amylose concentration of the permeate.

(B) Temperature of sample liquid is 50℃ 1 differential pressure is 0.3 kgf/
cm", and the linear velocity of the sample solution was varied to measure the permeation flux of the permeate and changes in amylose concentration over time. However, in the case of a linear velocity of 3.0 m/see, the linear velocity of the sample solution was Measurements were also made at a temperature of 60°C.The results are shown in the fourth section.
As shown in the figure. It can be seen that the higher the linear velocity, the higher the permeation flux. It can also be seen that both amylose concentration and permeation flux are higher at 60°C than at 50°C.

From the results obtained in Figures 3 and 4, the temperature of the sample solution is 50%.
The results of determining the amount of amylose permeation (the amount of permeation during 2 to 3 hours after the start of treatment) against the linear velocity at a temperature of 1 DEG C. and a differential pressure of 0.3 kgf/cm2 are shown in FIG. 5 (straight line (a)). Further, the results of determining the amylose permeation amount (same as above) with respect to the differential pressure at a sample liquid temperature of 50° C. and a linear velocity of 3 m/sec are also shown in FIG. 5 (straight line (b)).

These results show that for efficient separation of amylose, the smaller the differential pressure between the inside and outside of the ceramic tube, the better. It can also be seen that the higher the linear velocity of the sample liquid on the filtration membrane surface, the better.

Example 2 Example 1 (B) Temperature 60°C 1 linear velocity 3.0 m/se
c, 0 to 15 minutes, 45 to 60 minutes, and 275 to 3 minutes after the start of the experiment, following the permeate under the condition of differential pressure 0.3 kfg/cm2.
Take a predetermined amount of the permeate at 00 minutes, freeze-dry it, and store it at 1) 0°C.
After drying for 2 hours, the solid content was hydrolyzed with β-amylase, which decomposes only amylose into maltose, and the amount of maltose produced was measured. Table 1 shows the results. especially,
The amylose that permeated after 45 minutes showed extremely high purity.

Table Example 3 The above 1.1% corn starch suspension was heated to a liquid temperature of 6°C.
Linear velocity of sample liquid on ceramic tube filtration surface surface: 3.0
m/sec, differential pressure between the inside and outside of the ceramic tube 0.3 kg
The apparatus was cycled under conditions of f/cm2. The amount of sample liquid in the sample liquid tank was maintained at 2 dm3 as above.

When the operation was continued for 50 hours, the total permeate volume was 7.46
m'', and after concentration under reduced pressure, it was lyophilized and further dried at 1) 0°C for 2 hours. The yield of amylose was 3.0 g.

The amount of starch remaining in the entire unpermeated residue was measured to be 0.77 g.

Figure 6 shows changes over time in amylose concentration and permeate flux. The flux of permeate decreases for about 7 hours after the start, but after 7 hours it becomes almost constant, indicating efficient permeation.
It can be seen that separation has progressed.

Amylose in the obtained permeate did not precipitate and maintained a stable solution state.

〔Effect of the invention〕

According to the method of the present invention, unlike conventional methods, no precipitating agents such as n-butanol, nitroparaffin, or thymol, or enzymes such as α-1,6-gelcoditase, which cause a decrease in the purity of amylose, are used. Easy and simple operation.
High purity amylose can be produced continuously.

[Brief explanation of drawings]

FIG. 1 represents a ceramic filter. FIG. 2 is a conceptual diagram of an apparatus used in an embodiment of the present invention. FIG. 3 was measured in Example 1. Figure 2 shows changes over time in the amylose concentration of the permeate and the dependence of the permeate flux on the differential pressure between the inside and outside of the filtration membrane when the linear velocity is constant. FIG. 4 similarly shows changes over time in the amylose concentration of the permeate and the dependence of the permeate flux on the differential pressure between the inside and outside of the filtration membrane when the differential pressure is constant. FIG. 5 shows (a) the dependence of amylose concentration on linear velocity when the differential pressure is constant, and (b) the dependence of amylose concentration on differential pressure when the linear velocity is constant. FIG. 6 shows changes over time in the amylose concentration of the permeate and the amount of permeate obtained in Example 2.

Claims (4)

[Claims] (1) A step of filtering a suspension containing amylose and amylopectin obtained by treating starch in water at 40°C or higher through a filtration membrane with an average pore size of 0.01 to 0.1 μm to separate amylose in the filtrate. A method for producing amylose having (2) The method of claim (1), wherein the filtration is performed using a ceramic filtration membrane. (3) The method according to claim (1) or (2), wherein the filtration is performed by a cross-flow filtration method. (4) The method according to claim (3), wherein the cross-flow filtration method is performed at a membrane surface of the suspension supplied to the filtration membrane under a pressure difference between the inside and outside of the filtration membrane of 2 kgf/cm^2 or less. The method is carried out under conditions where the flow velocity is at a Reynolds number of 3,000 or more.