KR101697636B1 - Preparing method of multiple carboxylic acid-esterificated starch heterocompounds using low-temperature plasma - Google Patents

Abstract

Disclosed in the present invention is a method of preparing multiple carboxylic acid-esterified starch hetero-compounds by using low-temperature plasma. According to the present invention, the method comprises: a) mixing raw starch with a saturated carboxylic acid solution to produce a starch-carboxylic acid mixture dough having a water content of 25-45 wt%; b) extrusion-molding the starch-carboxylic acid mixture dough into a cylinder or film, and drying the same to a water content of 12-18 wt% to produce a reaction mixture; and c) placing the reaction mixture in a reaction chamber, injecting a reaction gas therein to reach a target vacuum pressure while irradiating microwaves to generate a low-temperature plasma, and exposing the reaction mixture to the low-temperature plasma for 1-30 minutes to obtain an ester compound that is between the carboxylic acid and the starch. The present invention, by using a low-temperature plasma treatment device and the low-temperature plasma which supplies free radicals, free electron and reactive chemical species, as a reaction catalyst, does not require a time-consuming drying process for producing a reaction mixture. Since the esterification between the starch and the carboxylic acid occurs at low temperature, browning or carbonization do not occur, and since the starch-carboxylic acid ester compound can be produced in a short reaction time, energy and working time can be economized.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a method for preparing a polycarboxylic acid-esterified starch hetero-

The present invention relates to an energy-saving and time-saving preparation method of a multicarboxylic acid esterified starch (starch-carboxylic acid ester heterogeneous compound), and more particularly, The present invention relates to a method for producing a multi-carboxylic acid esterified starch heterometallic compound by forming an ester bond between starch and a multiple carboxylic acid in a short time without browning.

Carboxylic acid forms an ester or amide bond through a condensation reaction involving hydroxyl groups and dehydration of biopolymers and synthetic polymers at a high temperature of 120 ° C or higher. These reaction mechanisms are used in many fields to improve the physical and rheological properties of industrial materials.

Carboxylic acids having two or more carboxylic functional groups such as succinic acid, malic acid, tartaric acid and citric acid have been widely used, and manufacturing biodegradable ion exchange resins for removing heavy metals (Wing, 1996; Sessa & Wing, 1999), improvement of mechanical tensile strength of biodegradable film (Reddy & Yang, 2010), and improvement of wrinkle resistance of cotton and silk (Yang et al., 1997). In addition, citric acid starch prepared through the double ester bond between citric acid and raw starch has been recognized to be highly applicable as a filler in the production of thermoplastic synthetic polymers and films by melt extrusion molding (Ma et al., 2009).

On the other hand, succinic acid, malic acid, tartaric acid and citric acid have been recognized as safe food additives in the food industry and they are used as raw materials for various processed foods and food additives. In recent years, multi-carboxylic acids of the food additive grade have been considered as highly safe reaction materials capable of replacing the conventional chemical modified starch reactants. In particular, citric acid starch prepared from citric acid as a reactant is known to form 3 to 90% resistant starch according to the reaction conditions and reaction method. It is known that no pathological symptom is observed and the digestive rate is slowed (Wiehner et al., 2007), which has been reported to have high potential as a functional starch material (Wepner et al., 1999;

For the formation of ester compounds between polycarboxylic acids and biopolymers (bioactive fractions, cellulose, and other non-ionic carbohydrate polymers), conventionally using a convection oven as a reactor, a high temperature of 120 ° C to 150 ° C for 3-7 hours Have been synthesized through heating reaction. At this time, the reaction mixture of the carboxylic acid and the biopolymer is prepared to have a moisture content of less than 10% at a pH of less than 6.5 and used as a raw material for the reaction.

The use of a convection oven as a reactor is a typical energy consuming and time consuming synthesis method, and it has disadvantages in that it causes browning and carbonization of biopolymers during the reaction to limit the use of the final ester compound or lower the yield of production . Also, the high temperature of the contact oven is not suitable for improving the mechanical properties of textile and biodegradable films.

Recently, a method of adding sodium hypophosphite, which is a powerful reducing agent, to the reaction mixture in the preparation of the reaction mixture was proposed in order to shorten the reaction time in the contact oven, (Reddy & Yang, 2010). However, sodium hypophosphite is used in the metal industry to reduce metal ions in the materials industry and is used as a drug for the nervous system in the pharmaceutical industry. It does not guarantee safety when remaining in the final ester compound. Therefore, when sodium hypophosphite is used as a reaction catalyst, it requires a further washing process.

On the other hand, by using an extrusion molding machine (Korean Registered Patent No. 10-0648093, published on Nov. 24, 2006) or a continuous circulation type heating reactor (Korea Registered Patent No. 10-1507563, Published on Apr. 8, 2015) A reaction process has been developed which shortens the reaction time and enables the mass production of ester compounds of carboxylic acid and starch. When an extrusion molding machine is used, an ester bond is formed between the carboxylic acid and the raw starch, but the reactivity is low so that there is no marked improvement in the physical, rheological and nutritional characteristics required by the industry. In the case of the continuous circulation type heating reactor, the reaction time was shortened by 3 to 7 times or more as compared with the case of using the reaction oven as the reactor, but in order to maintain the reaction efficiency similar to that of the reaction oven, It is still a process that consumes a lot of energy because it needs to be reacted by 20% higher than that. If the melting point of the carboxylic acid is lower than the reaction temperature of the continuous circulation type heating reactor, the carboxylic acid is melted and hinders smooth rotation of the screw of the continuous circulation type heating reactor, There is a problem in that a phenomenon of stopping the operation of the engine is generated.

In addition to using a convection oven, an extruder, and a continuous circulation heating reactor, a method of forming an ester compound between a carboxylic acid and a biopolymer by using a microwave oven has been studied by many researchers to date. When the microwave oven is used as a reactor, the reaction time can be increased to 120 ° C or higher in a shorter time than in the known reactors to form an ester compound of a carboxylic acid and a biopolymer in a short time, The browning and carbonization phenomenon still occurs, and this phenomenon has a problem in that the degree increases depending on the moisture content of the reaction mixture. In addition, it is difficult to control the temperature rise of the reaction mixture by microwave depending on the moisture content of the reaction mixture, and it is difficult to maintain the reaction temperature at a constant temperature, thus making it difficult to produce ester compounds of uniform quality and characteristics.

. Korean Patent No. 10-0648093, Date of Notification: November 24, 2006 . Korean Registered Patent No. 10-1507563, Published on April 08, 2015

It is an object of the present invention to provide a process for producing starch which is free from browning and carbonization of starch by using a low temperature plasma formed by using microwaves as a reaction catalyst and which is free from the problems of excessive browning and starch In the presence of a catalyst.

The present invention has been made to solve the above-mentioned problems, and it is an object of the present invention to at least partially solve the problems in the conventional arts. It can be understood.

According to the present invention, this object is achieved by a process for preparing a starch-carboxylic acid mixed dough comprising: a) mixing a raw starch and a saturated carboxylic acid solution to obtain a starch-carboxylic acid mixed dough having a water content of 25 to 40% by weight; b) extruding the starch-carboxylic acid mixed dough into a cylindrical or film form, and drying the starch-carboxylic acid dough to a moisture content of 12 to 18% by weight to prepare a reaction mixture; And c) introducing the reaction mixture into the reaction chamber so that a vacuum pressure inside the reaction chamber reaches a target vacuum pressure, and then introducing a reaction gas into the reaction chamber, To form a low-temperature plasma, and exposing the reaction mixture to a low-temperature plasma for 1 to 30 minutes to obtain an ester compound between the carboxylic acid and the starch. The multi-carboxylated esterified starch heterometallic compound . ≪ / RTI >

The reaction gas may be a nitrogen gas or a nitrogen-oxygen mixed gas, the vacuum pressure may be 0.5 to 5 KPa, and the power for oscillating the microwave may be 200 to 900 W.

The step a) comprises the steps of: a-1) calculating the amount of purified water to be added so that the moisture content of the starch batter is 25-40 wt%; a-2) preparing a saturated carboxylic acid solution by adding a carboxylic acid soluble in the purified water added amount calculated in the step a-1); a-3) The carboxylic acid saturated solution is added to the kneader together with the raw starch and kneaded within 10 minutes to prepare a starch-carboxylic acid mixture dough; And a-4) The starch-carboxylic acid mixed dough prepared in a-3) above was put into a polypropylene zipper bag, and the mixture was filled in a thermostat at 4 - 15 캜 for 12 hours. And further comprising the step of tempering.

The step b) comprises: b-1) injecting the starch-carboxylic acid mixed dough prepared in the step a) into a cylindrical or film form using a biaxial extrusion molding machine equipped with a molding nozzle at the exit of a round temple or a rectangular- Adding lost water from the starch-carboxylic acid mixed dough during extrusion; And b-2) are dried at a moisture content of 12 to 18% by weight in a hot-air dryer at 50 ° C to produce a reaction mixture, wherein the extrudate is crushed when the extrudate is cylindrical Step < / RTI >

The biaxial extrusion molding machine had a barrel temperature of 135 to 185 占 폚, a screw speed of 200 rpm and a feed rate of 100 g / min, the diameter of the circular yarn outlet was 4 mm, the rectangular yarn outlet size was 4 mm, And a width of 40 mm.

The step c) comprises: c-1) accumulating the reaction mixture prepared in the step b) on a glass tray to a thickness of 2 to 5 mm and accommodating the reaction mixture in the reaction chamber; c) adjusting the vacuum valve to a vacuum pressure of 0.5 to 10 KPa while injecting the reaction gas at a rate of 500 to 1,000 cc / min after the reaction chamber is evacuated to a vacuum pressure of 100 kPa; c-3) supplying a power of 200 to 1,000 W to the magnetron to oscillate the microwave to form a low-temperature plasma; And c-4) exposing the reaction mixture to a low-temperature plasma for 1 to 30 minutes and then pulverizing the mixture to 100 mesh to prepare a starch-carboxylic acid ester compound.

The low-temperature plasma processing apparatus includes a housing having a reaction chamber for forming and processing a low-temperature plasma; A microwave generating unit provided in the housing and having a magnetron for generating a microwave for forming a low-temperature plasma and supplying the microwave to the reaction chamber; A reaction gas injection unit for supplying a reaction gas composed of a nitrogen gas or a nitrogen-oxygen mixed gas into the reaction chamber; And a vacuum state forming unit for forming a vacuum state inside the reaction chamber by a vacuum pump.

The reaction gas injection unit includes a gas tank, a gas flow rate control valve installed in the gas supply pipe to regulate the amount of reaction gas supplied from the gas tank to the reaction chamber through the gas supply pipe, Wherein the vacuum state forming unit includes a vacuum valve installed in a hollow tube connecting the vacuum pump and the reaction chamber, and a hollow tube disposed between the vacuum valve and the vacuum pump, And a moisture adsorption device for adsorbing moisture of the air that is installed and discharged.

According to the present invention, by using a low-temperature plasma processing apparatus and using a low-temperature plasma for supplying free radicals, free electrons and reactive species as a reaction catalyst, a long-time drying process for producing a reaction mixture is not required, The starch-carboxylic acid ester compound can be produced within a short reaction time without sacrificing the browning and carbonization of the starch since an ester reaction occurs between the starch and the carboxylic acid, thereby providing energy and time savings .

FIG. 1 is a schematic configuration diagram for explaining a low-temperature plasma processing apparatus used in the present invention. FIG.
2 is a schematic block diagram for explaining a method for producing a starch-carboxylic acid ester heterologous compound according to the present invention.
Figure 3 is a photograph of the final reaction mixtures prepared by the process for preparing starch-carboxylic acid ester heterologous compounds according to the present invention and made using cylindrical and film-type discharge ports.
4 is a scanning electron micrograph of a starch-carboxylic acid ester heterologous compound according to the present invention.
Figure 5 is a graph showing the Fourier transform infrared (FT-IR) spectrum of a starch-carboxylate heterometallic compound according to the present invention.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the following description of the present invention, the well-known functions or constructions are not described in order to simplify the gist of the present invention.

1 is a schematic block diagram for explaining a low-temperature plasma processing apparatus used in the present invention, and FIG. 2 is a schematic block diagram for explaining a method for producing a starch-carboxylic acid ester heterogeneous compound according to the present invention .

The production method of the starch-carboxylic acid ester dissimilar compound on the basis of FIG. 2 will be described.

a) Step: Production of starch-carboxylic acid mixed dough (S1)

The raw meal and the saturated carboxylic acid solution are mixed to calculate the refinement that must be added to reach a water content of 25-40 wt%. The amount of purified water to be added can be calculated using the following equation. If the moisture content of corn starch is 12% and 2 kg of corn starch is used to produce a mixed dough having a target moisture content of 40%, the amount of purified water to be added to 2 kg of corn starch is 933 g.

Here, the water content of 25-40% means that the moisture content is 25-40% by weight based on 100% by weight of the mixed starch, and the water content mentioned below means the amount of water based on 100% by weight of the material .

In the present invention, an extrusion molding process is used to produce a reaction mixture for low-temperature plasma treatment, and the moisture content of the starch-carboxylic acid mixed dough should be in the range of 25 to 40% by weight. If the moisture content of the starch-carboxylic acid mixed dough is less than 25% by weight, clogging is often caused in the extrusion molding machine during the extrusion molding of the dough, thereby making it difficult to continuously produce the reaction mixture. When the moisture content exceeds 40% The starch and carboxylic acid mixture in the extruder can not be converted into a solution state and can be formed into a cylindrical form or a film form.

Therefore, when preparing the reaction mixture in a cylindrical form, the moisture content of the starch-carboxylic acid mixed dough is preferably 28% by weight, and when the reaction mixture is prepared in a film form, the moisture content of the starch- Do. The starch in the present invention may be any commercially available starch such as corn starch, wheat starch, rice starch, potato starch, corn starch, tapioca starch, pea starch, It is not suitable as a starch raw material of the invention. Because these starches have an amylose content of less than 5%, they can not be converted into a starch solution in all extrusion process conditions that are applied in the present invention to prepare a reaction mixture to produce an appropriate reaction mixture. Therefore, it is most preferable to use live starches having an amylose content of 20% or more as a starch raw material. (step a-1)

Then, the carboxylic acid is added to the purified water of the amount calculated in step a-1) until it no longer dissolves in the purified water, and the carboxylic acid crystals are removed through filtration under reduced pressure to prepare a carboxylic acid saturated solution. In the above example, a malic acid saturated solution can be prepared by adding 521 g of malic acid to 933 g of purified water. Carboxylic acids which can be used in the present invention include succinic acid, malic acid, tartaric acid and citric acid as a reaction material, and malic acid, tartaric acid and citric acid having high solubility are preferable. (step a-2)

Subsequently, the raw powder and the saturated solution of carboxylic acid were placed in a kneader and kneaded within 10 minutes to prepare a starch-carboxylic acid mixed dough. When the starch-carboxylic acid mixed dough is kneaded for more than 10 minutes, moisture is lost from the starch-carboxylic acid dough during kneading, so it is troublesome to add water as much as the loss of water when extruding the kneaded dough This is because. (step a-3)

Finally, the prepared starch-carboxylic acid mixed dough is put in a polypropylene zipper bag so that the moisture distribution can be uniformly distributed in the mixed dough. The zipper bag is sealed so that there is no space above the zipper bag and tempered in a thermostat at 4 to 15 ° C for 12 to 24 hours ) To prepare a starch-carboxylic acid mixed dough. When the starch-carboxylic acid mixed dough is sealed in the zipper bag, if there is a void in the upper part of the zipper bag, the uniform moisture content of the starch-carboxylic acid mixed dough can not be obtained due to condensation on the zipper bag during quenching. Also, when the temperature of the thermostat exceeds 15 ° C, the time for tempering can be shortened, but contamination by microorganisms may occur. If the temperature of the thermostat is less than 4 ° C, the movement of moisture in the mixed dough is not smooth, A carboxylic acid mixed dough can not be obtained. In addition, in the case of less than 12 hours, sufficient tempering can not be achieved, and if it exceeds 24 hours, microbial contamination may occur even if tempering is carried out at a low temperature. Therefore, it is most preferable that the starch-carboxylic acid mixed dough is tempered at 10 ° C for 18 hours. (step a-4)

b) Step: Preparation of the reaction mixture (S2)

First, the starch-carboxylic acid mixed dough prepared in the step a) was injected in a biaxial extrusion molding machine equipped with a round nozzle outlet (diameter: 4 mm) and a rectangular nozzle outlet (4 mm long and 40 mm wide) The extrudate was formed, and the barrel temperature was set so that the temperature was sequentially increased from the injection port of the barrel to the injection port. While the screw was rotated at 200 rpm, the starch-carboxylic acid mixed dough was biaxially extruded through the hopper at a rate of 100 g / And supplied to a molding machine. In this case, when the heating region of the barrel is divided into four regions from the injection port to the discharge port, the first region is 40 ° C, the second region is 90 ° C, the third region is 120 ° C, and the fourth region is 135-185 ° C To achieve the barrel temperature, an electric heater and a cooling water device are installed in the barrel to control the temperature of the barrel. The temperature of the outlet (fourth region) is determined by the melting point of the carboxylic acid used in the preparation of the starch-carboxylic acid mixed dough. When the temperature of the outlet is controlled to be lower than the melting point of the carboxylic acid used as the reactant, the melting of the carboxylic acid is insufficient and the rotation of the screw is stopped or the molding nozzle is clogged. In particular, when a molding nozzle of a rectangular discharge port is used for manufacturing a film extruded product, the mixed dough in the biaxial extrusion molding machine must maintain a sufficient molten state so that the melt is smoothly injected through the rectangular discharge port, Can be obtained. Therefore, the temperature of the outlet (the fourth zone) is 185 ° C for succinic acid, 175 ° C for tartaric acid, 155 ° C for citric acid and 135 ° C for malic acid.

The screw rotational speed is set to 200 rpm. The rotation speed of the screw is set to 200 rpm because the melt of the starch-carboxylic acid mixed dough is smoothly ejected from the molding nozzles of the round and rectangular discharge openings at the rotating speed of the screw at 200 rpm. If the rotation speed is more than 200 rpm, , And clogging occurred at the molding nozzle of the rectangular discharge outlet at less than 200 rpm. Therefore, it was preferable to set the screw rotation speed to 200 rpm for all the molding nozzles.

In addition, the starch-carboxylic acid mixed dough was fed by a biaxial extrusion molding machine at a rate of 100 g / min. When the starch-carboxylic acid mixed dough is supplied at a rate of 100 g / min or more, clogging occurs in all the molding nozzles. When the starch-carboxylic acid mixed dough is supplied at a rate of less than 100 g / min, It was difficult to keep the reaction mixture at a uniform temperature. (Step b-1)

Next, the cylindrical and film extrudate (see FIG. 3) extruded from the biaxial extrusion molding machine as described above is dried at 50 ° C. so that the moisture content is 12 to 18% by weight to prepare a reaction mixture, and the cylindrical extrudate is dried Followed by crushing. However, when a starch-carboxylic acid mixed dough prepared to have a water content of 25 to 30% by weight was injected from a biaxial extrusion molding machine to produce an extrudate, the moisture content thereof was in the range of 17 to 19% by weight There is no need to involve additional drying steps. (Step b-2)

c) Step: low temperature plasma treatment of the reaction mixture (S3)

Here, the low-temperature plasma processing apparatus 10 required for the low-temperature plasma treatment of the reaction mixture is constituted as shown in Fig.

The low temperature plasma processing apparatus 10 includes a housing 20 having a synthesis chamber 24 that is opened and closed by a door having a sight window 22 and in which a low temperature plasma is formed and processed and a microwave for forming a low temperature plasma A power supply 34 for supplying power to the magnetron 32 and a magnetron 32 for supplying power to the magnetron 32 and a power supply 32 for supplying power to the magnetron 32. [ A microwave generator 30 including a control panel 36 provided in the housing 20 to control the reaction chamber 34 and a reaction chamber 24 comprising a nitrogen gas or a nitrogen- A gas tank 42 connected to the reaction chamber 24 by a gas supply pipe so as to supply the gas into the synthesis chamber 24 through the gas supply line from the gas tank 42, Installed A reaction gas injection unit 40 including a flow rate control valve 44 and a flow meter 46 for measuring the amount of reaction gas supplied to the gas supply pipe and a vacuum pump 52, A vacuum valve 56 provided in a hollow tube for connecting the vacuum pump 52 and the synthesis chamber 24 so as to form the inside of the vacuum chamber 56 and the vacuum pump 52 in a vacuum state, And a vacuum state forming unit 50 having a water adsorption device 54 for adsorbing and removing moisture of air supplied to the pipe.

The reaction process of the reaction mixture using the low-temperature plasma processing apparatus 10 will be described in more detail.

In the process described above, the reaction mixture powder obtained from the cylindrical extrudate was stacked on a glass tray to a maximum thickness of 5 mm and accommodated in the reaction chamber. In this case, when the height of the reaction mixture powder accumulated on the glass tray exceeds 5 mm, the efficiency of forming the ester bond between the starch and the carboxylic acid by the low temperature plasma is lowered. Since the film-type reaction mixture dried at an appropriate moisture content does not exceed 4 mm in thickness, the door of the low-temperature plasma processing apparatus 10 is opened in a single layer on a glass tray, and then the reaction chamber 24 is accommodated. (Step c-1)

The vacuum valve 56 of the vacuum state forming unit 50 connected to the reaction chamber 24 accommodating the reaction mixture is opened and the vacuum pump 52 is operated so that the inside of the reaction chamber 24 is evacuated to a vacuum state at a vacuum pressure of 100 kPa Respectively. The reason for setting the reaction chamber 24 to the vacuum state is that the air of the various gas mixture remains, the injection of the reaction gas into the reaction chamber 24 is not smooth and the unstable low-temperature plasma is formed. In addition, the low temperature plasma treatment of the reaction mixture in the vacuum state promotes the ester bond between the starch and the carboxylic acid, and further promotes the evaporation of water in the reaction mixture to obtain a drying effect. (Step c-2)

Subsequently, the reaction gas is injected into the reaction chamber 24 at a rate of 500 to 1,000 cc / min while adjusting the vacuum valve 56 in a state where the vacuum pump 52 is operated, so that the vacuum pressure of the reaction chamber 24 is 0.5 To 5 KPa. Here, the reactive gas can be an inert gas (nitrogen, helium, argon) or a mixed gas of an inert gas and an oxygen gas. However, the nitrogen gas and the nitrogen-oxygen mixed gas in which the most stable low-temperature plasma is formed in the low temperature plasma apparatus 10 of the present invention are most preferable, but the mixing ratio in the nitrogen-oxygen mixed gas should not exceed 20% of the nitrogen gas. If the oxygen content in the mixed gas exceeds 20%, there is a risk of explosion during operation of the low-temperature plasma processing apparatus, and excessive ozone generation can corrode the inside of the reaction chamber and the vacuum pump. In addition, when the reaction gas is injected at less than 500 cc / min, it is easy to control the vacuum pressure in the reaction chamber, but there is a problem that the reaction efficiency is lowered due to unstable low temperature plasma. But the adjustment of the vacuum pressure in the reaction chamber 24 is not easy, so that it is difficult to perform the constant low-temperature plasma treatment on the reaction mixture. Therefore, it is most preferable to inject the reaction gas into the reaction chamber 24 at 500 cc / min. In addition, depending on the type of reaction gas injected, the vacuum pressure of the vacuum chamber 24 is variable. However, when the vacuum pressure is less than 0.5 KPa, the formation of the low-temperature plasma is incomplete. When the vacuum pressure exceeds 5 KPa, But the cost of the reaction gas is rapidly increased as compared with the increase of the reaction efficiency between the starch and the carboxylic acid. Therefore, when the nitrogen gas is used as the reaction gas, the vacuum pressure of the reaction chamber 24 is 0.7 KPa and the vacuum pressure of the reaction chamber 24 when the nitrogen-oxygen mixed gas (80:20, v / v) Is preferably 1.3 KPa. (Step c-2)

After the environment of the reaction chamber is established according to the above-described procedure, 200-1,000 W of power is supplied to the magnetron 32 to generate microwaves, and the reaction mixture is treated for 1 to 30 minutes. Here, when the power of less than 200 W is supplied to the magnetron 32, the microwave oscillation is not smooth and the low-temperature plasma can not be stably formed. When supplying power exceeding 1,000 W, 1 kW magnetron 32 is additionally provided, The magnetron 32 of the low-temperature plasma processing apparatus 10 must be replaced with a magnetron 32. In this case, the equipment cost and the operation ratio of the low-temperature plasma processing apparatus 10 increase exponentially. Therefore, it is preferable to oscillate the microwave from the magnetron 32 at a power of 900 W to effectively form an ester bond between the starch and the carboxylic acid while forming a stable low-temperature plasma. The reaction mixture may be exposed to the formed cold plasma for 1 to 30 minutes. If it exceeds 30 minutes, there is a problem with the overload of the magnetron (32), and when exposed for too short time, a sufficient reaction between starch and carboxylic acid can not be achieved. It is therefore desirable to expose the reaction mixture to the cold plasma for 20 minutes. (Step c-3)

As described above, the reaction mixture exposed to the low-temperature plasma may be pulverized and passed through a 100-mesh network to obtain a starch-carboxylic acid ester dissimilar compound. (S4)

[Test Methods]

. Temperature measurement of reaction mixture

The temperature of the reaction mixture surface was measured using an infrared thermometer when the reaction mixture was exposed to a low temperature plasma.

As a result, when the reaction mixture was exposed to the low-temperature plasma for 20 minutes, the surface temperature of the reaction mixture rose to a maximum of 38 ° C.

. Electron scanning microscope observation test

The starch-carboxylic acid ester heterogeneous compound prepared as described above was attached to an aluminum tray using a double-sided carbon tape and a gold and palladium mixture (60:40) was deposited on the reaction mixtures to a thickness of 20 nm to accelerate And observed using a field emission scanning electron microscope (JSM-6700F, Jeol Ltd., Tokyo, Japan) at a voltage of 5 KV. The result is shown in the attached photograph of FIG.

As shown in the photograph of FIG. 4, the starch-carboxylic acid ester dissimilar compound exhibited a shape of a continuous matrix of polygons of various sizes and showed a shape. Structures such as rapidly cooled after being melted by low temperature plasma were not observed I did.

. Fourier transform infrared spectrophotometer (FT-IR) test

의 해상도로 분석하였다. 그 결과는 첨부된 도 5의 그래프에 나타나 있다. FT-IR spectra of the starch-carboxylic acid ester heterologous compounds were determined using a Spectrum One System (Perkin-Elmer, Waltham, MA, USA). A pellet for FT-IR analysis was prepared by mixing and titrating potassium bromide (FT-IR grade,>99%; Sigma-Aldrich Co., St. Louis, Mo., USA) and starch samples in a weight ratio of 9: 1 . The FT-RI spectrum is 400-4000

Respectively. The results are shown in the attached graph of FIG.

파장(전분 안에 물 분자가 강하게 결합되어 있는 특성)에서 피크강도가 증하였으며, 1710~1750

파장범위에서 에스테르 작용기의 존재를 나타내는 새로운 피크가 형성되었다. 그래서 도 5의 결과는 전분 카르복시산 반응혼합물이 저온플라즈마에 노출되면서 전분과 카르복시산 사이의 에스테르(ester) 결합이 성공적으로 형성되었음을 확인하였다. As shown in Figure 5, the FT-IR spectrum of the starch-carboxylic acid ester heterologous compound was 1650

The peak intensity was increased at the wavelength (strong binding of water molecules in starch), and 1710 ~ 1750

A new peak indicating the presence of an ester functional group in the wavelength range was formed. Thus, the results of FIG. 5 confirm that ester starch bond formation between starch and carboxylic acid was successfully formed when the starch carboxylic acid reaction mixture was exposed to a low temperature plasma.

. Molar substitution degree

150 mL of anhydrous ethanol was mixed with 15 mL of 5N CH1 to prepare an ethanol-CH1 mixed solution.

The starch-carboxylate ester compound (2 g, db) was dispersed in an ethanol-CH1 mixed solution (50 mL) and stirred at room temperature for 30 minutes to remove the sodium salt ion-bonded to the starch-carboxylic acid ester dissimilar compound. The filtrate was subjected to filtration under reduced pressure on a funnel (FN1160-011G / G4, JOYLAB, Seoul, KOREA) to recover the starch-carboxylic acid ester dissimilar compound. The recovered sample was added with 80% aqueous ethanol solution (100 mL), stirred at room temperature for 10 minutes and decompressed. This washing procedure was repeated until the pH of the filtrate reached 7 ~ 7.5 (500 mL of 80% aqueous ethanol solution was used). The recovered samples were dispersed in anhydrous ethanol (50 mL) The mixture was stirred for several minutes, filtered under reduced pressure, and dried at 45 캜 to obtain a sample for measurement of molar substitution degree. The analytical sample (1 g, db) was mixed with a 75% ethanol aqueous solution (30 ml) in a 250 ml Erlenmeyer flask, and the mixture was incubated at 50 ° C for 30 min. After cooling to room temperature, 0.5 N NaOH (10 mL) was added and the mixture was stirred at room temperature for 24 hours. After 24 hours, 3 drops of phenol pralane solution was added and the mixture was back-titrated with 0.1 N HCl standard solution (F = 1.002, Duksan Co., Ansan, Gyeonggi, Korea) Further titration. The amount of carboxylic acid liberated in the starch-carboxylic acid ester dissimilar compound was determined from the amount of 0.1 N CH1 consumed over the second time. The molar degree of substitution of the starch-carboxylate heteromeric compound was calculated as a ratio of the number of moles of carboxylic acid to anhydrous glucose in the starch-carboxylic acid ester dissimilar compound (Ma et al., 2008)

. Swelling power and solubility

The mixture was dispersed in 0.5 g (d.b) of a starch-carboxylic acid ester dissimilar compound and 25 mL of deionized water, heated in a boiling water bath of 95 DEG C for 30 minutes, cooled in a cold water bath for 20 minutes, and then centrifuged at 2,500 g for 20 minutes. The supernatant was transferred to a 100 mL constant volume flask, diluted with deionized water, and the precipitate was weighed as it was, and the swelling power was determined by the following equation. The solubility was determined according to the following equation by analyzing the total sugar in the supernatant of a 100 mL constant volume flask by the sulfuric acid-phenol method.

[Comparative Example]

Citric acid and succinic acid esters of common corn starch and polycarboxylic acids are prepared by the continuous circulation heating reactor which is currently applied in literature and the molar substitution degree thereof is measured according to the above described test method Respectively. The results are shown in Table 1.

Molar substitution degree of citric acid starch and succinic acid starch prepared by continuous circulation type heating reactor Carboxylic acid
Kinds pH density Reaction temperature Screw speed Number of passes Consumed
Reaction time Molar substitution degree Citric acid 3.5 10% 150 ℃ 10 rpm 5 times 34 minutes 0.016 Succinic acid 3.5 10% 150 ℃ 10 rpm 5 times 35 minutes 0.012

The present invention relates to a process for preparing a starch-citrate ester heterogeneous compound by low temperature plasma treatment using the method of the present invention, wherein the starch-citric acid ester heterogeneous compound is prepared by using common corn starch and polycarboxylic acid as a reactant, and the molar substitution degree thereof is analyzed according to the above- Table 2 shows the results. At this time, in order to compare the molar substitution of the comparative example, the concentration of citric acid instead of the citric acid saturation solution was adjusted to 10% of the dry weight of the common corn starch. The reaction gas was a mixture gas of nitrogen and nitrogen and oxygen (80:20, v / v) , And the powders obtained by crushing the cylindrical extrudate were used as the reaction mixture. The other conditions of the low temperature plasma treatment were the same with the power of 900 W and the exposure time of 20 minutes.

Molar substitution degree of starch - citrate ester heterologous compound synthesized by low - temperature plasma treatment Reaction gas (composition) Molar substitution degree Nitrogen gas (100%) 0.038 Nitrogen-oxygen mixed gas (nitrogen: oxygen = 80: 20, v / v) 0.037

The molar substitution degree of the starch-citrate ester dicarboxylic acid compounds prepared using the low temperature plasma was higher than the molar substitution degree (0.016) of the citric acid starches of the comparative example by about two times.

A cylindrical and film-type reaction mixture was prepared from common corn starch and tartaric acid in the form of polycarboxylic acid as a reaction material, and the reaction mixture was exposed in a low-temperature plasma formed by supplying 900 W of power using a nitrogen gas as a reaction gas for 20 minutes The molar substitution degree of the starch-tartaric acid ester dissimilar compound is shown in Table 3.

Effect of reaction mixture type on the degree of molar substitution of starch-tartrate heterometallics synthesized by low-temperature plasma treatment Reaction mixture form Presence or absence of tartaric acid Molar substitution degree Cylindrical
Do not add 0.003 Use saturated solution 0.047 Film type
Do not add 0.005 Use saturated solution 0.104

The molar substitution degree was also analyzed for the cylindrical and film type reaction mixtures prepared only with purified water without the addition of tartaric acid. Treatment of the low temperature plasma with the presence of some water in the reaction mixture could also produce carboxyl functional groups in starches without carboxyl functionalities. In the case of the cylindrical and film type reaction mixture prepared according to the above-mentioned method using the stannic acid saturated solution, the production of the reaction mixture in the film form showed a higher degree of molar substitution than the production of the reaction mixture in the cylindrical form. That is, the film type reaction mixture was in the form of a sample suitable for low temperature plasma treatment.

A film-type reaction mixture of malic acid and succinic acid was prepared from common corn starch and polycarboxylic acids, and starch-malic ester heterogeneous compound prepared by exposing the film-type reaction mixture to a low-temperature plasma formed at a power of 900 W for 20 minutes using nitrogen gas as a reaction gas, - Swelling power and solubility of the succinic ester heterogeneous compound were analyzed according to the above test method and are shown in Table 4.

Swelling power and solubility of starch-malic acid and starch-succinic acid ester dicarboxylic compounds Analytical sample Swelling power Solubility Carboxylic acid-free reaction mixture (control) 4.40 53.30 Carboxylic acid-free low-temperature plasma treatment sample 8.71 45.11 Starch-malate ester Dioxin compound 9.24 11.31 Starch-succinic acid ester heterogeneous compound 8.20 17.90

The swelling power was increased and the solubility was decreased even when only the low temperature plasma was treated. In addition, starch - malic acid and starch - succinic acid ester dyes increased swelling power more than 2 times and decreased the solubility by 3 to 4.5 times compared to the control. These effects are the effect of forming an ester compound between starch and carboxylic acid.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, It is obvious to those who have. Accordingly, it should be understood that such modifications or alterations should not be understood individually from the technical spirit and viewpoint of the present invention, and that modified embodiments fall within the scope of the claims of the present invention.

10: low-temperature plasma processing apparatus 20: housing
22: perspective window 24: reaction chamber
30: Microwave generator 32: Magnetron
34: Power supply 36: Control panel
40: reaction gas injection part 42: gas tank
44: gas flow control valve 46: flow meter
50: Vacuum condition forming part 52: Vacuum pump
54: Water absorption device 56: Vacuum valve

Claims (8)

a) preparing a starch-carboxylic acid mixed dough having a moisture content of 25 to 40% by weight by mixing a raw starch and a saturated carboxylic acid solution;
b) extruding the starch-carboxylic acid mixed dough into a cylindrical or film form, and drying the starch-carboxylic acid dough to a moisture content of 12 to 18% by weight to prepare a reaction mixture; And
c) injecting the reaction gas into the reaction chamber so that the vacuum pressure inside the reaction chamber reaches the target vacuum pressure after placing the reaction mixture in the reaction chamber, Generating a low-temperature plasma, and exposing the reaction mixture to a low-temperature plasma for 1 to 30 minutes to obtain an ester compound between the carboxylic acid and the starch.
Process for the preparation of multicarboxylic esterified starch heterobifunctional compounds using low temperature plasma. The method according to claim 1,
Wherein the reaction gas is composed of a nitrogen gas or a nitrogen-oxygen mixed gas, the vacuum pressure is 0.5 to 5 KPa, and the power for oscillating the microwave is 200 to 900 W,
Process for the preparation of multicarboxylic esterified starch heterobifunctional compounds using low temperature plasma. The method according to claim 1,
The step a)
a-1) calculating the amount of purified water to be added such that the moisture content of the starch dough is 25-40 wt%;
a-2) preparing a saturated carboxylic acid solution by adding a carboxylic acid soluble in the purified water added amount calculated in the step a-1);
a-3) The carboxylic acid saturated solution is added to the kneader together with the raw starch and kneaded within 10 minutes to prepare a starch-carboxylic acid mixture dough; And
a-4) The starch-carboxylic acid mixed dough prepared in a-3) above was put into a polypropylene zipper bag, and the top portion of the dough was piled up without any space at the top and put in a thermostat at 4 ~ Lt; RTI ID = 0.0 > 1, < / RTI >
Process for the preparation of multicarboxylic esterified starch heterobifunctional compounds using low temperature plasma. The method according to claim 1,
The step b)
b-1) The starch-carboxylic acid mixed dough prepared in the step a) is injected into a cylinder or a film by using a biaxial extrusion molding machine equipped with a molding outlet at the exit of a round temple or a rectangle outlet, Adding lost water from the dough during extrusion; And
b-2) The produced cylindrical or film extrudate is dried at a moisture content of 12 to 18% by weight in a hot-air dryer at 50 캜 to prepare a reaction mixture, and when the extrudate is cylindrical, the extrudate is pulverized Lt; RTI ID = 0.0 > 1, < / RTI &
Process for the preparation of multicarboxylic esterified starch heterobifunctional compounds using low temperature plasma. 5. The method of claim 4,
In the biaxial extrusion molding machine,
When the barrel temperature is 135 to 185 DEG C, the screw speed is 200 rpm, and the amount of the raw material is 100 g / min, the diameter of the circular yarn outlet is 4 mm and the size of the rectangular yarn outlet is 4 mm long and 40 mm wide ≪ / RTI >
Process for the preparation of multicarboxylic esterified starch heterobifunctional compounds using low temperature plasma. The method according to claim 1,
The step c)
c-1) accumulating the reaction mixture prepared in the step b) in a glass tray to a thickness of 2 to 5 mm and accommodating the reaction mixture in the reaction chamber;
c) adjusting the vacuum valve to a vacuum pressure of 0.5 to 10 KPa while injecting the reaction gas at a rate of 500 to 1,000 cc / min after the reaction chamber is evacuated to a vacuum pressure of 100 KPa;
c-3) supplying a power of 200 to 1,000 W to the magnetron to oscillate the microwave to form a low-temperature plasma; And
c-4) exposing the reaction mixture to a low-temperature plasma for 1 to 30 minutes, and then pulverizing the mixture to 100 mesh to prepare a starch-carboxylic acid ester compound.
Process for the preparation of multicarboxylic esterified starch heterobifunctional compounds using low temperature plasma. 7. The method according to any one of claims 1 to 6,
The low-temperature plasma processing apparatus includes:
A housing having a reaction chamber for forming and processing the cold plasma;
A microwave generating unit provided in the housing and having a magnetron for generating a microwave for forming a low-temperature plasma and supplying the microwave to the reaction chamber;
A reaction gas injection unit for supplying a reaction gas composed of a nitrogen gas or a nitrogen-oxygen mixed gas into the reaction chamber; And
And a vacuum state forming unit for forming a vacuum state inside the reaction chamber by a vacuum pump.
Process for the preparation of multicarboxylic esterified starch heterobifunctional compounds using low temperature plasma. 8. The method of claim 7,
The reaction gas injection unit includes:
A gas flow rate control valve installed in the gas supply pipe to regulate the amount of reaction gas supplied from the gas tank to the reaction chamber through the gas supply pipe; Comprising a flow meter for measuring,
The vacuum state-
A vacuum valve installed in a hollow tube connecting the vacuum pump and the reaction chamber, and a moisture adsorption device installed in a hollow tube between the vacuum valve and the vacuum pump for adsorbing moisture of air discharged from the hollow tube, ≪ / RTI >
Process for the preparation of multicarboxylic esterified starch heterobifunctional compounds using low temperature plasma.

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