JPH01225601A - Saccharification of starch by microwave heating - Google Patents

Abstract

PURPOSE:To carry out liquefaction and saccharification of starch in a series of processes to thereby facilitate the saccharification, by putting a starch emulsion obtd. by adding water to starch in a pressure vessel and heating it by microwave heating. CONSTITUTION:Starch 2 is put in a pressure vessel 1 and distilled water is added thereto. The vessel is degassed, sealed, and is placed in a microwave oven and irradiated with microwaves 3 to elevate rapidly the temp. and to keep the temp. in the range of 190-240 deg.C. The whole mass is thereby solubilized and a saccharified soln. is directly obtd. from the raw material starch emulsion. The liquefaction and saccharification can be carried out in a series of process by said procedures. Only water is used as the solvent and the soln. after the saccharification can be easily handled. Moreover, the disposal of waste is unnecessary.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application: The present invention relates to a method for efficiently performing liquefaction and saccharification of starch by microwave heating under water.

Prior art and its problems: Methods for hydrolyzing and saccharifying starch can be broadly divided into saccharification methods using acids and saccharification methods using enzymes.

In the acid saccharification method, for example, starch powder contains about 0,
Add 2 to 0.4 t of an inorganic acid such as hydrochloric acid or sulfuric acid or an organic acid such as oxalic acid to a pH of 1.5 to 2.0 at 110 to 150°C to about 40 to 60% By heating for minutes, sugar solutions such as starch syrup and glucose are obtained.

Since this sugar solution has a low pH, it is neutralized by adding calcium salts, sodium salts, etc., and then filtered, decolorized, evaporated and concentrated, or dried to produce products. This process requires a jacketed stirring tank, a heat exchanger, a high-pressure crosstalk device, etc.

In the enzymatic saccharification method, a liquefaction enzyme is first added to the starch pores,
Heat to 60-110°C and liquefy. Next, the pH is adjusted, and a saccharifying enzyme is added for hydrolysis to obtain a sugar solution. Processing after saccharification can be performed in almost the same way as the acid saccharification method. and,
In this process, stirring tanks, basic tanks, etc. are used for liquefaction and saccharification.

Furthermore, as a means of improving starch saccharification using enzymes, many enzymes that directly obtain sugar from starch pores have been proposed, but they are not suitable for industrial use due to extremely long saccharification times and low yields. There are some difficulties.

Therefore, it eliminates the generation of waste mainly caused by additives, shortens the time required for saccharification, eliminates the need for column equipment or external heat or pressure supply lines, and efficiently saccharifies starch. A means was needed.

Means for solving the problem: The present invention heats starch in a hydrated state using microwaves,
The problems of the conventional technology were solved by sequentially proceeding liquefaction and saccharification. According to the present invention, since microwave heating is used, starch can be easily heated to high temperatures regardless of whether it is batch-type or continuous-type.
It can be placed under high pressure and saccharifies starch in a short time without requiring excessive equipment. Continuous microwave heating was proposed by the present inventors (Japanese Unexamined Patent Publication No. 61-1
No. 9098) A continuous microwave heating device can be used.

Structure and operation of the invention: In the method of the present invention, raw milk powder is prepared by adding only water, placed in a pressure-resistant container through which microwaves can easily pass, and irradiated with microwaves in a microwave open chamber. The temperature of the starch raw material in the pressure container rises rapidly, and the starch material is liquefied with almost no gelatinization occurring. That is, the soluble components begin to increase at around 100°C, and when the temperature exceeds 160°C, the soluble components increase significantly. With this increase in soluble components, 18
The amount of glucose produced increases rapidly from around 0°C. Depending on the type of starch raw material, the optimum temperature at which the maximum amount of glucose produced can be obtained ranges from 190 to 240°C, and as the temperature is increased to 240°C or higher, the temperature increases through each starch raw material.
Conversely, the amount of glucose produced decreases.

Therefore, the structure of the present invention is that in the starch saccharification method in which various types of starch raw materials are decomposed and converted into low-molecular compounds: Starch pores made by simply adding water to starch are used as starch raw materials in a pressure-resistant container. The saccharified liquid is obtained directly from the raw milk starch powder by introducing it; irradiating it with microwaves to rapidly raise the temperature; and maintaining it in the temperature range of 190 to 240°C.

The holding time in the temperature range of 190 to 240°C may be short;
Even if there are variations due to the selection of the microwave frequency or output, etc., the flow rate and flow rate should be set so as to satisfy the above conditions for about 20 minutes or less in the case of a batch type, and in the case of a continuous type.

The mechanical situation during this operation is to raise the optimum temperature for glucose production in the shortest possible time using a microwave with high output, and to maintain it constant at this optimum temperature to achieve the maximum amount of glucose production. This is the condition. When processed under these optimal conditions, a glucose production amount of almost too% can be obtained from 95 yen. This phenomenon is caused by starch types such as underground stem starches such as potatoes, kuzu, and sweet potatoes.
Although the optimum temperature is slightly different for both tuber starch (tuber starch) and ground starch (seed starch) such as corn, wheat, and rice, they have similar tendencies.

Examples: Hereinafter, specific examples of the present invention will be described based on the drawings.

As starch samples, corn starch was selected as a representative of aboveground starch (seed starch), and potato starch was selected as a representative of underground stem starch (tuber starch). These starches are highly utilized, consumed in large quantities, and highly productive. Both starches were not particularly purified, and the moisture content was 11.1% for cornstarch and 16.8% for potato starch.

Microwave heating was performed using two methods: a batch method and a continuous method.

Batch-type microwave heating uses a thick-walled test tube made of pressure-resistant glass as the pressure-resistant container (1), as shown in Figure 1.
4 g of each starch raw material (2) was added to the container, 16 bottles of distilled water were added thereto, the container was sufficiently degassed, and the container was sealed. The sealing part (4) was a stainless steel screw cap. Then, this pressure-resistant container (1) was heated in an open microwave (Toshiba TMB-8210 model, frequency 2450±50 MHz, output 2.4 KW). The starch was saccharified by short-term microwave heating within 18 minutes. During this time, the behavior of starch decomposition based on the passage of time and changes in temperature was observed, and it was confirmed that the desired saccharification was completed.

In such batch-type microwave heating, both corn starch and potato starch do not decompose as water-soluble components unless heated at a temperature of 120° C. or higher. When heated to a temperature higher than this, water-soluble components rapidly increase, and 19
The entire amount is water-solubilized at a temperature of 0 to 240°C, preferably 200 to 220°C. At heating temperatures exceeding 240°C, on the contrary, water begins to become insolubilized.

On the other hand, heating any starch to a temperature of 200°C or higher is essential for producing reducing sugars. 210-2 for cornstarch
The maximum value was 72.4% in the range of 17℃, but in the case of potato starch, there was a tendency to show resistance to microwave heating, and it did not show an extreme value below 220℃, and at 220℃
．． It is desirable to generate 0% glucose and heat to about 240°C. The PR of the solution rapidly decreased when heated above 120°C, and at 220°C it was 2.8 to 3.1. A decrease in pH indicates acid formation.

Next, the case of continuous microwave heating will be explained. As the microwave heating device, a continuous microwave heating device manufactured by Nippon Kagaku Kikai Seizo Co., Ltd. was used, the main part of which is shown in FIG. This continuous heating device αq uses microwaves (3
) The pressure vessel (1), which is the irradiated part, is installed inside the shield housing@, and the waveguide α' is connected from the microwave oscillator aυ to the
It has a structure in which the pressure vessel (1) is irradiated with microwaves and heated through the pressure vessel (1).

The starch raw material (2) stored in the raw material tank α frame is fed into the pressure-resistant container (1) by the supply pump αη, heated and saccharified, and received in the receiver α→. αυ is an accumulator, and α→ is a pressure regulating valve. In the continuous force generator αO used in this example, the frequency of the microwave oscillator α°C was 2450±50 MHz, and the output was 4.9 KW.

The pressure container (1) has a diameter of 4c11 and a length of 1001? 1 liter alumina ceramic tube, and 5 to 5 i (W
/W) in water to a concentration of 2.4 to 20.
The mixture was allowed to flow through the pressure vessel (1) at a flow rate of 0.47 hours.

In this continuous type microwave heating, water-soluble components increase due to heating above 120'C, similar to the batch type. At temperatures below 200°C, water-soluble components do not reach a maximum value and in order to obtain nearly 100% solubilization, 190°C
'-240°C, preferably 220 to 225°C is required.

In the case of cornstarch, the amount of free glucose reached a maximum value of 71.0% at 220°C, but it rapidly decreased when the temperature exceeded 240°C. In addition, in the case of potato starch, the maximum value is not given at temperatures below 230°C, and the maximum value is 63.
It showed 6%.

In the continuous heating device 01 used in this example, the microwave oscillator αυ has a frequency of 2450±50 MHz and an output of 4.9.
It is KW.

As another example of continuous microwave heating, the oscillation frequency in the continuous heating device may be set to other than the above, for example, 915M.
Hz, etc., and at the same time set the output as an appropriate output value, the same trend of saccharification state was obtained.

Overall, when starch is decomposed and saccharified, the decomposition characteristics graphs for corn starch shown in Figure 3 and potato starch shown in Figure 4 show similar trends in both batch and continuous processes. The advantage of the method of the present invention is that it can be carried out according to the amount to be treated, installation circumstances, etc.

Effects of the Invention: According to the present invention, by heating starch in the microwave under water, it is possible to proceed with liquefaction and saccharification in a series of steps. Since only water is used as a solvent, handling of the solution after saccharification is easy, and there is no need to dispose of waste residue.

According to the method of the present invention, maltooligosaccharides can also be prepared by changing the heating conditions, and the method has great industrial applicability.

[Brief explanation of the drawing]

1 and 2 show specific examples of the method of the present invention, with FIG. 1 being a batch-type method and FIG. 2 being a continuous-type method. FIG. 3 is a graph of the decomposition characteristics of starch, and FIG. 4 is a graph of the decomposition characteristics of potato starch.

Claims (1)

[Scope of Claims] 1. In a starch saccharification method in which various types of starch raw materials are decomposed into low-molecular compounds: Milk starch obtained by simply adding water to starch is introduced into a pressure-resistant container as a starch raw material; A method for saccharification of starch using microwaves, characterized by: irradiating the starch with microwaves to rapidly raise the temperature; and maintaining the temperature in a temperature range of 190 to 240°C to obtain a saccharified liquid directly from the raw starch powder. 2. Introduce the starch raw material into a pressure-resistant container in a batch manner,
The method for saccharification of starch by microwave heating according to claim 1, characterized in that the saccharification of starch is maintained in a temperature range of 240° C. for a certain period of time. 3. When introducing the starch raw material into the pressure container continuously, 1.
The method for saccharifying starch by microwave heating according to claim 1, wherein the flow rate and flow rate are set to maintain the temperature in a temperature range of 90 to 240°C for a certain period of time.