JPH059441B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a method for gelatinizing starch and an apparatus therefor, and includes a method that allows the degree of gelatinization of starch to be controlled at room temperature depending on the purpose, and an apparatus for continuously gelatinizing starch raw materials. It provides: [Prior art] The conventional method for producing pregelatinized starch mainly consists of making an aqueous slurry of the main starch grains, spreading this thinly on a drum dryer and heating it, and pregelatinizing the starch to form a thin film of dried pregelatinized starch. There was a lot to do. In some cases, kneading and heating are performed using an extruder, or heating and humidification are performed by passing superheated steam into a tank container. However, based on this premise, there are quite a few proposals that aim to improve quality by specifying detailed processing conditions. For example, starch granules are aged after being heated at a temperature that swells but does not destroy them (Japanese Patent Application Laid-Open No.
114300), one that heats water slurry to the swelling temperature and then rapidly cools it at a specific rate (Special Publication No. 114300),
30202), heating at a temperature of at least 50°C or higher and at least 10°C above the specific gelatinization initiation temperature (Japanese Patent Publication No. 1983-47600), raw starch granules suspended in an aqueous alcohol solution. Examples include a slurry which is heated under pressure to gelatinize it (Japanese Patent Application Laid-Open No. 63-49054). Further moisture 14~
30%, starch adjusted to PH5 or less at a temperature of 50 to 250
℃ and a pressure of 20 to 100 Kg/cm ² , and a special technique to extrude raw starch with a moisture content of 30 to 60% at a temperature of 70 to 150 ℃ and a pressure of 100 Kg/cm ² or less. Publication No. 57-8706 can also be found. [Problems to be Solved by the Invention] As already mentioned, many of the known techniques cited above are based on the heating means of raw starch granules in the form of a slurry containing at least 40% by weight of water; This is an improvement of processing technology based on the current situation. Making a heating means an essential requirement for equipment has many implications, including the burden of equipment costs, an increase in work management items, an increase in quality variation factors, the complication of maintenance inspections, considerations for the work environment, and cumulative increases in energy costs. This creates a load on equipment operation. Since the energy cost assumes a moisture content of at least 40%, and generally 100 to 300%, the cost required for drying is an extremely important factor. In addition, if the water content is relatively low, it includes a procedure for chemically adjusting the pH to 5, and also involves heating means. The object of the present invention is to provide a new method for producing pregelatinized starch in which the heating means, which has not been suspected by anyone in the field of production, is removed from the apparatus, and an apparatus for carrying out this method. [Means for Solving the Problems] The method for producing pregelatinized starch according to the present invention is 5 to 40%
Raw starch granules containing % water by weight are continuously compressed under high pressure between a pair of cylindrical rolls without heating.
The above-mentioned problem is solved by continuously expressing the gelatinized starch, and more specifically, by controlling the pressure used for squeezing, and arbitrarily adjusting the gelatinization ratio of the expressed starch. did. The equipment used in this method includes a raw material supply hopper and a compression roll consisting of a pair of cylindrical rolls provided at the bottom of the hopper that are parallel to each other and rotate in opposite directions. A screw rod is installed vertically, a pre-pressure chamber is formed by the side wall at the bottom of the hopper and the lower end of the screw rod, and a pair of cylindrical rolls installed directly below the pre-pressure chamber can be moved telescopically through the distance between their axes; Also disclosed is a horizontal compression roll in which a screw rod, a precompression chamber, and a pair of cylindrical rolls are arranged perpendicularly to the hopper in this apparatus while maintaining the same mutual positional relationship. [Operation] When explaining the operation of the present invention, the following 5 to 40
Raw starch granules containing % by weight of water will be referred to as "starch raw material". It is a well-known principle that when a substance is compacted by mechanical pressure, the compacted substance generates heat in order to suppress the molecular movement of the substance, and as the pressure increases, the calorific value of the substance also increases. . On the other hand, it is a well-known principle that starch raw materials undergo gelatinization by heating, and that if the starch raw material has a high moisture content, it will be gelatinized at a low heating temperature, and if the starch raw material has a low moisture content, it will gelatinize at a high heating temperature. Focusing on the above two principles, the present invention investigated the correlation between the pressing force necessary for consolidation, heating temperature, and gelatinization rate through experiments. This method was based on the discovery that starch was easily gelatinized. In other words, the starch raw material is supplied from the upper part of the hopper, is forced to move inside the hopper by the spiral surface of the screw rod that rotates through the center of the hopper, and is subjected to pressure, and this pressure is rapidly increased to create a preload. When the starch reaches the chamber, the forced feeding and compression action destroys the raw three-dimensional structure of the starch particles due to intermolecular friction, causing various changes in the starch and causing the raw starch to rapidly gelatinize. This phenomenon is similar to the gelatinization phenomenon of starch due to heating, but it has recently been elucidated that when the two are compared, there are many similarities as well as differences. For example, when observing the appearance of starch using a microscope, the polarization cross disappeared and the particle size increased.
When looking at changes in the crystalline portion by DSC analysis and powder X-ray diffraction, a decrease in heat of gelatinization and a decrease in crystallinity can be seen. However, a report was submitted that when looking at the gelatinization characteristics using amylograph, each showed a characteristic curve. (“Use of high pressure in food” edited by Rikimaru Hayashi, page 23)
(First edition published on July 15, 1989) At the time of the experiment, it was determined that the reason starch gelatinization progressed even without any heating when pressurized between cylindrical rolls was due to the exothermic effect of compaction, but subsequent reports Therefore, it seems correct to interpret the phenomenon as being the high-pressure compaction itself.
The compaction effect of the cylindrical rolls can be controlled to the desired state by varying the rotational speed of the screw rod or by changing the gap between both rolls, but as exemplified in the later examples (Table 1), the compression force between the rolls is 2.50～
3.30TON/cm ² is desirable, at least 1000Kg/cm ²
Do not cut. This high pressure is a major difference from the prior art, and is a notable difference from the requirement that the pressure should not exceed 100 kg/cm ² for extrusion types using extruders or buffing machines. If we consider the difference in the consolidation effect between roll compression and conventional extrusion methods, we can see that in the former, the force applied to the starch is rapidly consolidated, causing an apparent volume change and changing the three-dimensional structure in a short period of time. The difference is that while the former is broken and gelatinized, the latter applies kneading pressure as a high viscosity fluid. Therefore, in order to quickly obtain fluidity, a temperature above a certain value must be required for gelatinization in order to add (or increase) water and uniformly disperse (mix). In terms of the time required for gelatinization, the conventional technology that uses only heating of a low-concentration slurry takes the longest time, followed by another conventional technology that uses heating, kneading, and extrusion using an extrusion method, followed by high-pressure roll compression and non-heating. It can also be said that the method of the present invention undergoes instantaneous (one second or less) metamorphosis. [Example] Hereinafter, Example 1 of the present invention will be described based on FIG. 1. Cylindrical rolls 1 _A , 1 _B are connected to shafts 3 _A , 3 _B ,
The shaft _3A is fixed to the fork 6, and the shaft _3B is supported to the bracket 7. The fork 6 is connected to the rod 5 of the hydraulic cylinder 4. The bracket 7 and the hydraulic cylinder 4 are fixed to the support 8. The hydraulic pressure is transmitted to the rod 5, fork 6, and shaft _3A of the hydraulic cylinder 4, and the cylindrical roll _1A moves and presses against the fixed cylindrical roll _1B . Therefore, by controlling the hydraulic pressure, it is possible to control the pressing force between the pair of cylindrical rolls _1A and _1B . A pre-pressure chamber 2 is attached to the upper part of the cylindrical rolls 1 _A and 1 _B , and the upper part of the pre-pressure chamber 2 is connected to a hopper 9 . A screw 10 as an example of a screw rod is provided on the center line between the hopper 9 and the preload chamber 2, the lower end of the screw 10 is fitted into the preload chamber 2, and a spiral blade is provided in the direction to send the starch raw material 20 downward. is connected to a motor 11 attached to the top of the hopper 9. When the rotation of the screw 10 is increased to feed a large amount of starch raw material, the amount that is not discharged by the cylindrical rolls _1A and 1B accumulates in the preload chamber 2, reducing the voids in the starch raw material D and making it denser so as to increase the bulk density. be converted into A supply port 13 for the starch raw material D is provided at the upper part of the hopper 9, and the starch raw material D is inputted and supplied from there. The starch raw material fed into the hopper 9 is fed into the preload chamber 2 by the rotation of the screw 10 and densified, and is densified between the cylindrical rolls 1 _A and 1 _B whose pressurizing force is controlled by the hydraulic cylinder 4. The starch α-D, which has changed to a predetermined degree of gelatinization while further undergoing consolidation and heat generation, is continuously discharged. Next, a second embodiment of the present invention will be explained based on FIG. 2. The cylindrical rolls _12A , _12B are connected to shafts _32A , _32B , the shaft _32A is pivotally supported on the fork _6B , and the shaft 32A is supported on the fork 6B.
_B is pivotally supported by bracket 7B. Fork _6B is connected to rod _5B of hydraulic cylinder _4B . Bracket _7B and hydraulic cylinder _4B are fixed to support _8A . The hydraulic pressure is transmitted to the rod _5B of the hydraulic cylinder _4B , the fork _6B , and the shaft _32A , and the cylindrical roll 12
The roller _A is configured to move and come into pressure contact with the fixed side cylindrical roll _12B , and the other configurations are the same as in FIG. 1 of the embodiment (1). That is, in Example (2) of the present invention, a pair of cylindrical rolls 1 _A , 1 _B , 12 _A , and 12 _B are provided to pressurize the starch raw material D in two stages, and compared with Example (1). It is possible to lengthen the pressurizing time of the starch raw material D. Therefore, it becomes possible to lengthen the exothermic retention time of the starch raw material D, and the control range of the degree of gelatinization of starch is expanded. The above two embodiments have been explained, but in both embodiments, the starch raw material flows in a straight line from above to below, whereas the pre-pressure chamber and cylindrical rolls are arranged horizontally, and the flow is perpendicular to the hopper. A coordinate transformation of . . . , also constitutes a preferred embodiment. (Figure 3) [Effects of the Invention] As described above, the present invention is a method for gelatinizing starch that does not require the addition of conventional chemical substances, heating means, etc. Therefore, the conventional procurement of chemical substances, addition of chemical substances, superheated steam generator, heater, and heating process can be omitted, which is highly effective in saving resources and energy. . What is noteworthy is the ability to arbitrarily vary the ratio of pregelatinized starch from the same starch raw material depending on the purpose; for example, as shown in Table 1,
By controlling the rotational speed of the screw (i.e. by controlling the densification of the starch raw material in the preload chamber) and by controlling the hydraulic pressure of the cylinder (i.e. by controlling the compaction between the cylindrical rolls), the same starch It was confirmed that three types of α-starch with different degrees of gelatinization could be obtained from the raw materials.

【table】

[Table] In recent years, the variety of instant foods has increased, and α-starch, which is an important raw material, is required to have various degrees of gelatinization. Therefore, since the starch gelatinization device of the present invention can control the degree of starch gelatinization with simple operations and can continuously produce controlled alpha-starch,
It is highly effective in producing α-starch in small to large quantities.

[Brief explanation of the drawing]

FIG. 1 is a front sectional view of Example 1 of the present application, FIG. 2 is a front sectional view of Example 2 of the present application, and FIG. 3 is a front sectional view of another Example 3. 1 _A , 1 _B ...Cylindrical roll, 2...Preload chamber, 9
... Hotsupa, 10 ... Screw, 12
_A , 12 _B ... Cylindrical roll.

Claims (1)

[Claims] 1 Raw starch granules containing 5 to 40% water by weight are continuously compressed under high pressure between a pair of cylindrical rolls to continuously squeeze out gelatinized starch without heating. A method for producing pregelatinized starch, characterized by: 2. The method for producing pregelatinized starch according to claim 1, characterized in that the pregelatinization ratio of the starch to be expressed is arbitrarily adjusted by controlling the pressing force used for squeezing. 3 In a compression roll consisting of a raw material supply hopper and a pair of cylindrical rolls provided at the bottom of the hopper and rotating in parallel to each other in opposite directions, a spiral rod is vertically provided vertically through the inside of the hopper at a variable rotational speed, and the bottom of the hopper is A method according to claim 1 or 2, characterized in that a preload chamber is formed by the side wall of the screw rod and the lower end of the screw rod, and the pair of cylindrical rolls mounted directly below the preload chamber are movable telescopically in the distance between their axes. Equipment used. 4 In claim 3, for the hopper, screw rods and
3. An apparatus for use in the method according to claim 1, wherein the pre-pressure chamber and the pair of cylindrical rolls are arranged horizontally in series while maintaining the same mutual positional relationship.