KR101507563B1 - Production method of indigestible citrate cross-linked starch - Google Patents

Abstract

A production method of indigestible citrate cross-linked starch is disclosed. The production method of indigestible citrate cross-linked starch comprises the steps of: a)mixing starch and a citric acid solution having a pH of 1.0-6.5 then making a starch-citric acid mixture by mixing the citric acid solution and dry starch in the ratio of 1:1; b)making a reaction mixture by drying the starch-citric acid mixture until the water content becomes 7.5 %; and c) obtaining amorphous or crystal indigestible citrate cross-linked starch by inducing a cross-linkage reaction between the starch molecules and the citric acid by passing the reaction mixture through a continuous flow thermal reactor under the conditions that the reaction temperature is 130-190 deg. C and the screw rotary velocity is 10-50 rpm. According to the specification of the present invention, by circulating the reaction mixture repetitively in the continuous flow thermal reactor, starch′s carbonizations can be minimized and indigestible citrate cross-linked starch containing a high content of enzyme resistant starch can be manufactured.

Description

TECHNICAL FIELD [0001] The present invention relates to a method for producing starch crosslinked starch,

More particularly, the present invention relates to a method for producing starch-crosslinked starch which is capable of minimizing carbonization of starch by utilizing a continuous-circulation heating reactor, The present invention relates to a process for producing an indigestible citric acid crosslinked starch capable of producing starch.

 In general, enzyme-resistant starch refers to a starch substance that is not degraded by starch degrading enzymes in the body through the digestive tract (Fuentes-Zaragoza, Riquelme-Navarrete, S, & P, 2010). Enzyme resistant starches have been devised for patients with type 2 diabetes and obesity who ultimately want to regulate blood glucose response characteristics and insulinaemic responses or to limit excessive absorption of monosaccharides produced from starch degradation (Higgins, 2004; Kim et al., 2013; Sharma, Singh, & Ritika, 2008). Recent studies have shown that enzyme-resistant starches provide a feeling of satiety, maintain a healthy bowel with dietary fiber and prebiotics, improve blood glucose response and insulin-mimic response, help with weight loss and maintenance, (Higgins, 2004; Lee, Yoo, & Lee, 2012; Sharma et al., 2008) have been reported to have beneficial physiological and chemical properties such as improving lipid composition. Recently, resistance starch has been recognized as a physiochemically beneficial food material that inhibits metabolic diseases and promotes health.

These enzyme resistant starches are classified into four types, from type 1 to type 4. Type 1 is natural starches that are physically protected from starch hydrolysates, Type 2 is undamaged or undigested natural starches separated from potatoes and beans, Type 3 is amorphous starches that have been recrystallized or aged, 4 type is chemically modified modified starches (Kim et al., 2013; Sajilata, Singhal, & Kulkarni, 2006; Sharma et al., 2008). Resistance of starch degrading enzymes belonging to Forms 1 to 3 to the starch degrading enzymes is drastically lowered due to heat treatment of aqueous solution or food group containing high water content, et al., 2013; Sharma et al., 2008). However, chemically modified starches, type 4 enzyme resistant starches, have been reported to be rich in slow-digestible and non-digestible starches after undergoing various food processing operations. In particular, phosphorylation of phosphorus oxychloride and sodium trimetaphosphate with starch is known to be the most effective method for producing enzyme-resistant starch (Kim et al., 2010; Woo & Seib, 2002). Nevertheless, as environmental and food safety concerns increase, many food processors are in the process of either producing chemically modified starches or refraining from adding chemically modified starches to their products (Kim & BeMiller, 2012; Villwock & BeMiller , 2005).

On the other hand, there is research to replace the starch-crosslinking reaction between starch and citric acid as an alternative to the production of enzyme-resistant starch through phosphorylation crosslinking of starch. Citric acid forms a citric anhydride by dehydration reaction when it is heated to 120 ° C or higher. It binds to the starch through esterification reaction with the hydroxyl group of starch, The esterification reaction occurs and ultimately produces citric acid crosslinked starch. Traditionally, semi-dry heating reactions using a convection oven or a distributor are used for the cross-linking reaction between starch and citric acid. However, in order to produce a high content (35% or more) of enzyme-resistant starch through semi-dry heating reaction, it is common to react for 3 to 9 hours at a temperature of 140 ° C or more, and the amount of starch-citric acid mixed powder Increasing the reaction time further increases the economical efficiency by requiring a large-scale heating device. Also, since starch is exposed at high temperature for a long time, carbonization reaction occurs in the starch during the heat treatment, resulting in a reduction in the weight of the final product (reduction in production yield) and a decrease in processing aptitude due to browning.

As a conventional technique for esterification reaction between starch and citric acid, Korean Patent Registration No. 10-0648093 (published on Nov. 24, 2006) discloses a method for producing enzyme-resistant starch using an extrusion molding method .

The method for producing an enzyme-resistant starch using such an extrusion molding method is characterized in that starch is mixed with citric acid, vitamin C, and heat at a barrel temperature of 95 to 110 占 폚, a water content of 30 to 50% (w / w) and a screw rotation speed of 250 to 350 rpm Stable liquefying enzyme or high amylose is added and extrusion molding is carried out. In the extrusion molding, carbonic acid gas or carbonic acid in a critical state is injected for extrusion molding.

However, the production method of the enzyme-resistant starch using the extrusion molding method according to the related art has a relatively low injection temperature (95-110 ° C), a high screw rotation speed (250-350rpm) and a moisture content of 30-50% w / w), the efficiency of the multi-esterification reaction between starch and citric acid in the extruder was extremely low, resulting in the formation of a small amount of enzyme-resistant starch in the extrudate compared to the high energy consumption of the extrusion molding process, - There was a problem that the citric acid melt sticks to the screw and the inner surface of the reactor to contaminate the reactor.

Further, when the extrusion molding method for injecting carbon dioxide gas or critical-state carbon dioxide gas is used, it is inconvenient to input carbon dioxide gas into the high-pressure state (10 atm or more), and the installation cost of the pressurizing equipment And operating costs are additionally required and the efficiency of esterification between starch and citric acid is lowered due to the carbon dioxide gas injected into the starch-citric acid melt, resulting in less enzyme-resistant starch production. In addition, the starch-citric acid mixture must be extruded, dried and then pulverized again, thereby deteriorating productivity.

Korean Patent No. 10-0648093 (Notification Date: November 24, 2006)

It is an object of the present invention to provide a means by which a continuous cycle heating reactor is utilized to minimize the carbonization of starch and to produce an indigestible citric acid crosslinked starch containing a high content of enzyme resistant starch.

It is another object of the present invention to provide a starch containing a high content of enzyme resistant starch.

The above object can be accomplished by a method of preparing a starch-citric acid mixture comprising: a) preparing a citric acid solution having a pH of 1.0 to 6.5 and mixing it with starch, wherein the citric acid solution and the dried starch are mixed at a ratio of 1: b) drying the starch-citric acid mixture to a moisture content of 7.5% to prepare a reaction mixture; And c) passing the reaction mixture through a continuous circulation heating reactor at a reactor temperature of 130 ° C to 190 ° C and a screw rotation speed of 10 to 50 rpm for 3 to 9 times to effect a crosslinking reaction between the starch molecule and citric acid To obtain a crystalline or amorphous indigestible citric acid crosslinked starch. The present invention also provides a method for producing an indigestible citric acid crosslinked starch.

In step (a), a citric acid solution is prepared by mixing anhydrous citric acid and sodium citrate in a weight ratio of 3: 1 and dissolving in purified water, wherein 0.1 to 0.4 kg of a citric acid mixture and 0.6 to 0.9 kg of purified water are mixed The method comprising the steps of:

In the step a), 1 kg of the citric acid solution and 1 kg of the dried starch are put into a kneader and mixed for 20-30 minutes.

The step b) comprises transferring the starch-citric acid mixture mixed by the kneader to a stainless steel tray, hot-air drying at 45 ° C to have a water content of 7.5% and pulverizing to prepare a crystalline reaction mixture, , The reaction mixture prepared in the step b) is repeatedly passed through the continuous circulation type heating reactor 3 to 9 times to obtain an indigestible citric acid crosslinked starch.

The step b) comprises: b-1) transferring the starch-citric acid mixture mixed in the kneader to a stainless steel tray, hot-air drying at 45 ° C so that the moisture content becomes 7.5%, and pulverizing the mixture into 60- Producing; b-2) The crystalline reaction mixture was passed through an extruder and the barrel temperature was gradually increased from 40 ° C to 130 ° C as the sample was moved from the sample injection port area to the injection area of the sample melt. The screw was rotated at 150 rpm, Feeding the crystalline reaction mixture to the extruder through a hopper at a rate of 100-120 g / min into a sample inlet of the barrel; b-3) injecting purified water into the sample inlet of the barrel such that the water content of the crystalline reaction mixture is 25%; And b-4) extruding the extrudate having passed through a circular nozzle (diameter: 4 mm) of the extruder, drying the extrudate at 80 ° C with hot air so as to have a water content of 7.5%, and pulverizing the resultant mixture into 60 mesh to prepare an amorphous reaction mixture .

The continuous-circulation-type heating reactor used in step c) may have a structure in which the extrusion molding machine is a basic skeleton and the injection port and the molding nozzle are removed.

The above object can be achieved by the indigestible citric acid crosslinked starch according to the present invention, which is prepared by the above-mentioned method for producing an indigestible citric acid crosslinked starch and contains enzyme resistant starch.

According to the present invention, by utilizing a continuous-circulation-type heating reactor, the starch-citric acid reaction mixture is continuously rotated and moved by screw rotation of a continuous-circulation-type heating reactor and subjected to a heating reaction, And it is possible to provide an effect of manufacturing an indigestible citric acid crosslinked starch which minimizes the carbonization of starch and contains a high content of enzyme resistant starch.

1 is a schematic block diagram for explaining a method for producing amorphous indigestible citric acid crosslinked starch according to the present invention.
FIG. 2 is a schematic block diagram for explaining a preparation method of the crystalline indazole-resistant citric acid crosslinked starch according to the present invention.
Figure 3 is a scanning electron micrograph and X-ray diffraction diagram of crystalline and amorphous reaction mixtures prepared according to the present invention.
FIG. 4 is a graph showing Fourier transform infrared (FT-IR) spectra of the indigestible citric acid crosslinked starch prepared using the continuous-circulation heating reactor according to the present invention.
FIG. 5 is a photograph for explaining appearance color characteristics of starch prepared according to the method for producing indigestible citric acid crosslinked starch according to the present invention and appearance color characteristics of starch prepared using a convection oven.

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.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic block diagram for explaining a method for producing amorphous indigestible citric acid crosslinked starch according to the present invention.

1, a method for producing amorphous indigestible citric acid crosslinked starch will be described.

Prior to the description of the manufacturing method, although not shown in the drawing, the continuous-circulation-type heating reactor was constructed by removing a discharge port and a forming nozzle with a barrel-opening type biaxial extrusion molding machine (Incheon Machinery, Incheon) It has 4 parts of heating part from sample injection port to discharge part and the heating reaction temperature is controlled by using electric heater and cooling water. At this time, the rotation and movement of the specimen was made by a biaxial screw rotating in the same direction, each screw diameter was 3.0 cm, and the length and diameter ratio (L / D ratio) was 25: 1.

a) Step

. Citric acid solution preparation step (S1)

A citric acid solution is prepared, with a pH of 1.0 - 6.5. At this time, the citric acid solution is prepared by mixing anhydrous citric acid and sodium citrate in a weight ratio of 3: 1 and dissolving in purified water. As described above, when anhydrous citric acid or sodium citrate is used alone, the pH must be adjusted with an alkali solution or an acid solution. Therefore, in the present invention, an additional alkali solution (for example, an aqueous solution of sodium hydroxide) Is to achieve the pH of the citric acid solution required for the cross-linking reaction between starch and citric acid without the addition of an acid solution (e.g. aqueous hydrochloric acid solution).

The citric acid solution in the pH range of 1.0 to 6.5 is essential for the ester reaction between the starch and citric acid. For the crosslinking reaction with high reaction efficiency, the pH of the citric acid solution is most preferably 3.5. If the pH is below 3.5, the hydrolysis of the starch may proceed during the reaction time, resulting in a decrease in the yield of the product during the additional washing process. Further, the single ester reaction is more likely to occur than the crosslinking of the starch by the double ester reaction The enzyme resistant starch content may decrease in the product. On the other hand, when the pH is higher than 3.5, the esterification reaction efficiency between starch and citric acid is low, so that citric acid crosslinked starch containing a high amount of enzyme resistant starch can not be obtained.

On the other hand, the concentration of the citric acid solution, that is, the amount of citric acid contained in the citric acid solution is 10 to 40% based on the entire citric acid solution. For example, based on 1 kg of a citric acid solution, 0.1 to 0.4 kg of a citric acid mixture and 0.6 to 0.9 kg of purified water are mixed. The concentration of such citric acid has the following effects. That is, when less than 10% citric acid is added, the enzyme resistant starch in the final product is formed to less than 10%, and when citric acid is added in an amount exceeding 40%, excess citric acid is melted when passing through a continuous circulation heating reactor Accumulation and solidification phenomenon (or clogging of the molding nozzle) occurs on the surface of the screw, and the rotation of the screw is stopped. Therefore, the citric acid concentration of the citric acid solution is 10 to 40%, preferably 40%.

. The starch-citric acid mixture preparation step (S2)

A 1: 1 mixture of citric acid solution with 10 - 40% citric acid concentration and dried starch (corn starch) is made into a citric acid starch - citric acid mixture. That is, 1 kg of citric acid solution and 1 kg of dried starch are put in a kneader (Hobart Co., Troy, OH, USA) and mixed for 20-30 minutes.

b) Step

. The reaction mixture preparation step (S3)

 The starch-citric acid mixture is dried to a water content of 7.5% to prepare a reaction mixture. Specifically, it is as follows.

First, the starch-citric acid mixture mixed by a kneader is transferred to a stainless steel tray, and then dried at 45 ° C by hot air blowing to have a water content of 7.5%. The mixture is pulverized and passed through a 60 mesh standard net to prepare a crystalline reaction mixture. (Step b-1)

Next, the crystalline reaction mixture was injected through a molding nozzle (round, diameter: 4 mm) in a barrel-opening type full-biaxial biaxial extrusion molding machine in a barrel opening-closing type so that the temperature gradually increased from the sample inlet of the barrel to the injection area of the sample melt , While the screw is rotated at 150 rpm, the crystalline reaction mixture is fed through the hopper to the extruder at a rate of 100-120 g / min. In this case, when the heating region of the barrel is divided into the first region, the second region, the third region and the fourth region from the sample inlet to the injection region of the sample melt, the first region is 358 ° C, the second region is 90 ° C, The barrel temperature is controlled so that the third zone is at 110 ° C and the fourth zone is at 130 ° C. To achieve this, an electric heater and a cooling water device are installed in the heating part of the barrel so that the temperature of the heating part of the barrel is increased from the sample inlet to the injection area of the sample melt. Controlling the temperature of the barrel (particularly, the extruder fourth zone barrel heating section) as described above causes clogging of the molding nozzle when the barrel temperature is controlled to be higher than the above-described temperature condition, The reaction mixture of the starch and the citric acid solution is not expanded or the barrel temperature is maintained at the set temperature condition. (b-2)

The screw rotational speed is 150 rpm. The reason why the rotation speed of the screw is set to 150 rpm is because it shows the highest expansion ratio when the rotation speed of the screw is 150 rpm, and the amorphous starch is more easily produced as the expansion is larger. When the rotational speed of the screw is adjusted to less than 150 rpm, the starch particles in the crystalline starch-citric acid mixture undergo acid hydrolysis by citric acid, and the starch-citric acid melt leaks into the joints between the upper and lower ends of the barrel, And when the rotation speed of the screw is controlled to exceed 150 rpm, the expansion ratio of the expanded material is low, and the amorphous reaction mixture can not be produced.

The crystalline reaction mixture is then fed into a hopper of an extruder to pass the mixture through a barrel, where the water content of the starch-citric acid melt in the barrel is 25%, using a metering pump to feed the purified water. (b-3) At this time, the reaction mixture in which starch and citric acid are mixed is supplied to the sample inlet of the barrel through the hopper at a rate of 100 to 120 g / min. If the reaction mixture is supplied at a rate of less than 100 g / min, it is difficult to keep the extruder barrel temperature constant. If the reaction mixture is supplied at a rate exceeding 120 g / min, jamming may occur at the middle of the forming nozzle or screw Lt; / RTI > Thus, the reaction mixture is fed to the barrel through the hopper at a rate of 100-120 g / min. If the water content of the reaction mixture supplied to the hopper is less than 25%, clogging occurs frequently in the barrel or the forming nozzle, and the operation is not smooth. When the moisture content exceeds 25%, sufficient expansion does not occur, The starch-citric acid reaction mixture can not be prepared.

Then, the extrudate extruded from the extrusion molding machine is dried by hot air at 80 ° C to have a water content of 7.5%, pulverized and passed through a 60-mesh standard net to obtain an amorphous reaction mixture. (b-4)

c) Step

. (S4)

The reaction mixture obtained by the above-mentioned process is passed through a continuous circulation type heating reactor at a reactor temperature of 130 ° C to 190 ° C and a screw rotation speed of 10-50rpm for 1-9 times to effect crosslinking reaction between starch molecules and citric acid To obtain amorphous indigestible citric acid crosslinked starch.

That is, the continuous-circulation heating reactor was operated under the conditions of a reaction temperature (reactor temperature) of 130 ° C, a screw rotation speed of 20 rpm or a reaction temperature of 140 ° C, and a screw rotation speed of 20-30 rpm. If the reaction temperature is less than or equal to 130 ° C and the screw rotational speed is less than 10 rpm or more than 50 rpm, the amorphous reaction mixture will stick to the inner wall of the screw or reactor, It can not be discharged from the heating reactor, so that citric acid crosslinked starch can not be produced.

Through the process as described above, it is possible to obtain an indigestible citric acid crosslinked starch containing a large amount of enzyme-resistant starch (S5)

Meanwhile, FIG. 2 is a schematic block diagram for explaining a method for producing the crystalline indazole-reducing citric acid crosslinked starch according to the present invention.

As shown in FIG. 2, the crystalline starch-citric acid crosslinked starch is prepared by transferring a starch-citric acid mixture mixed in a kneader to a stainless steel tray at a temperature of 45 ° C., Dried and pulverized to obtain a crystalline reaction mixture, and then in step c), the reaction mixture is passed through a continuous circulation type heating reactor three to nine times to induce a cross-linking reaction between the starch molecule and citric acid to produce a crystalline indazole- Except that starch is obtained in the same manner as in the previous embodiment.

. Scanning Electron Microscopy and X-ray diffractometer test

The morphological characteristics and crystal structure of the crystalline and amorphous reaction mixture prepared as described above were examined using a scanning electron microscope and an X-ray diffractometer. The morphological characteristics of the two reaction mixtures were determined by attaching each reaction mixture to an aluminum tray using a double-sided carbon tape, and a gold and palladium mixture (60:40) (SUPRA ^TM 35VP, Carl Zeiss Microimaging, Inc., Thornwood, NY, USA) at an accelerating voltage of 3 kV. In addition, the X-ray diffraction diagrams of the two reaction mixtures were obtained by placing each sample (about 2 g) in a desiccator containing a saturated sodium bromide saturated solution at room temperature (~ 24) to obtain an equilibrium moisture content after uniformly to 14.8% X-ray diffractometer using (Siemens D5000, Madison, WI, USA), from the output voltage and power of 40 kV and 30 mA to 0.3 ^o diffraction interval and 3 ^o / min diffraction speed four to X-ray diffraction diagram was obtained in the range of 30 ^° diffraction angle (2 0 ). The results are shown in the scanning electron micrographs and the X-ray diffraction chart of FIG. 3 attached hereto.

As shown in FIG. 3, the crystalline reaction mixture maintained a starch particle structure and exhibited strong peaks at X-ray diffraction angles of 13 to 14 ^o , 17 ^o , 18 ^o, and 23 ^o , Respectively. On the other hand, the amorphous reaction mixture disintegrates the starch particle structure and shows a plate-like irregular structure. X-ray diffraction also shows the X-ray diffraction pattern of a typical amorphous structure in which all the peaks showing the presence of the crystal structure disappeared. Therefore, it was confirmed that the method of preparing the amorphous reaction mixture used in the present invention is appropriate.

. Fourier transform infrared spectrophotometer (FT-IR) test

Fourier transform infrared spectra of starch - citric acid crosslinked starch were investigated in order to investigate the cross - linking reaction between starch and citric acid in a starch - citric acid reaction mixture passed through a continuous circulation heating reactor. I.e., citric acid crosslinked starch powder BIO-RAD FTS3000 IR in a 2 cm ^-1 resolution and 600-4000 cm ^-1 wavelength range in order to determine the cross-linking reaction has occurred between the starch with continuous circulation reactor and heated citric acid Spectral scanners were investigated. The results are shown in the graph of FIG. 3 attached hereto.

As shown in FIG. 4, the FT-IR spectrum of the indigestible citric acid crosslinked starch showed an increase in peak intensity at 1650 cm-1 wavelength (strongly binding of water molecules in starch) compared to that of natural corn starch, and 1710 A new peak was formed in the -1735 cm-1 wavelength range (presence of ester functionality). Thus, the results of FIG. 4 confirm that the starch-citric acid reaction mixture passes through the extruder and forms ester bonds between starch and citric acid.

. Determination of indigestible starch content

The content of enzyme-resistant starch in citric acid crosslinked starches was measured using a Resistant starch assay kit from Megazyme according to AACC approved method 32-40. Pancreatic α-amylase (1 g) was mixed with 100 mM sodium maleate buffer (pH 6.0), diluted to 100 mL, and stirred for 5 minutes. 1 mL of the diluted amyloglucosidase solution (300 U / mL) was added thereto, and the supernatant was centrifuged at 3,000 rpm for 10 minutes to obtain a starch digestion solution. 100 mg (db) of citric acid-crosslinked starch samples and 4 mL of starch digestion solution were mixed and incubated at 37 ° C for 16 hours in an incubator (200 strokes / min) for enzyme reaction. Then, 4 mL of 99% The supernatant was transferred to a 100-mL constant volume flask, and 8 mL of 50% ethanol aqueous solution was added to the precipitate. The supernatant was centrifuged at 3,000 rpm for 10 minutes, and the supernatant was collected in a 100-mL constant volume flask And 100 mM sodium acetate (pH 4.5) was added to the solution, which was used as a soluble starch sample. The insoluble enzyme resistant starch samples were centrifuged and the residue was mixed with 2.0 mL of 2 M KOH and dissolved in an ice water bath for 20 minutes. After mixing with 8 mL of 1.2 M sodium acetate (pH 3.8) solution, amyloglucosidase solution (3300 U / mL) was added, and the reaction was carried out in a constant-temperature water bath at 50 ° C for 30 minutes. The reaction mixture was transferred to a 100-mL constant volume flask and prepared by deionized water. 0.1 mL of soluble starch and insoluble enzyme resistant starch samples were mixed with 3 mL of GOPOD reaction reagent, and the mixture was developed at 50 ° C for 30 minutes. The absorbance was measured at 510 nm, and the enzyme resistance was measured using an enzyme resistance starch content calculation program provided by Megazyme The starch content was calculated.

. Chromaticity measurement

The color characteristics of the starch crosslinked with indigestible citric acid were analyzed using a colorimeter (CD-300d, Konica, Osaka, Japan) and the lightness, redness, and yellow color were shown.

. pH measurement

Citric acid crosslinked starch 1 g (d.b) was weighed directly into a 250 mL beaker, 100 mL of deionized water was added, and the mixture was stirred at room temperature for 1 hour and pH was measured using a pH meter.

. Measurement of reaction efficiency

Citric acid To extract citric acid not participating in the cross-linking reaction, 1 g (db) of the indigestible citric acid crosslinked starch was added to a 50 mL centrifuge tube and 40 mL of 50% (v / v) aqueous ethanol solution was added After shaking at room temperature for 30 minutes, the supernatant is separated by centrifugation at 2500 g and transferred to a 100 mL constant volume flask. The same operation was carried out by adding 40 mL of a 50% (v / v) aqueous ethanol solution to the precipitate, and the supernatant was transferred to a 100 mL constant volume flask and diluted to 100 mL with deionized water. Take 25 mL of the solution from a regular flask and transfer it to a 250 mL Erlenmeyer flask. Add 2-3 drops of 0.1% (w / v) phenolphthalein solution and titrate with 0.1 N NaOH standard solution (activity 1.002) .

Where 0.0064 g represents the amount of citric acid corresponding to 1 mL of 0.1 N NaOH and 4 represents the dilution factor.

Citric acid was also recovered by quantitative determination of the starch-citric acid reaction mixture (not passed through a continuous circulation heating reactor) according to the procedure described above.

Where W _o is the amount (g) of citric acid recovered from the starch-citric acid reaction mixture and W 1 is the amount of citric acid (g) not participating in the crosslinking reaction recovered from the citric acid crosslinked starch.

. Sour Strength Evaluation

To evaluate the acidity of citric acid crosslinked starch, 10 different citric acid solutions were prepared in the range of 0 ~ 3%, and 10 sensory evaluation sites were selected through difference discrimination and strength ranking test. Selected sensory evaluators were trained on the intensity of acidity with 0%, 0.05%, 0.1%, 0.3%, 0.5%, 1%, 1.5%, 2.0%, 2.5% and 3.0% citric acid solution. For the sensory evaluation, 1 g of citric acid crosslinked starch was mixed with 50 mL of distilled water, stirred for 30 minutes, centrifuged at 2500 g for 20 minutes, and the supernatant was recovered to evaluate the sour taste. Purified water was provided between the samples to allow the mouth to be dug. The intensity of sour taste was measured by 9 point scale method. 0 point had no sour taste, 5 point had medium sour taste, and 9 point had strong sour taste.

[Comparative Example]

Table 1 shows the enzyme-resistant starch content of citric acid-crosslinked starch by semi-dry heating reaction using a convection oven, which is currently applied in the literature for the cross-linking reaction between starch and citric acid.

Semi-Dry Heat Reaction Conditions and Enzyme Resistant Starch Content for Preparation of Crystalline Citric Acid Crosslinked Starch Crystalline reaction mixture Semi-dry heating reaction conditions
Enzyme resistant starch content
(%) Citric acid concentration
(%) pH Temperature
(° C) Time ^{1 )}
(h) 10 3.5 150 5 39.5 40 3.5 150 5 75.4

¹⁾ The time taken to react 200 g of the crystal-type reaction mixture

[Example 1]

In order to investigate the effects of the screw speed of the continuous-circulation heating reactor on the enzyme-resistant starch content of the crystalline citric acid crosslinked starch, the rotation speed of the screw of the continuous-circulation heating reactor in which the shaping nozzle was removed (open) was measured at 10, 30 and 50 rpm , The crystalline reaction mixture was fed into a continuous circulation type heating reactor at a rate of 100 g / min to prepare citric acid crosslinked starch. The operating conditions of the continuous-circulation heating reactor and the enzyme-resistant starch content are shown in Table 2.

Effect of Rotation Speed of Continuous Circulating Heating Reactor on the Enzyme Resistant Starch Content of Crystalline Citric Acid Crosslinked Starch Crystalline reaction mixture Continuous circulation type heating reactor operating condition Enzyme resistant starch content
(%)
Citric acid concentration
(%) pH reaction
Temperature
(° C) screw
Rotation speed
(rpm) Pass
collection
(time) Actual work
Time ^{1 )}
(h) 10 3.5 150 10 5 1.25 25.5 10 3.5 150 30 5 0.92 21.7 10 3.5 150 50 5 0.67 16.3 40 3.5 150 10 5 1.40 89.4 40 3.5 150 30 5 0.98 68.9 40 3.5 150 50 5 0.65 54.7

^{1 )} Actual working time for producing 2500 g of indigestible citric acid crosslinked starch

As shown in Table 2, the enzyme resistant starch content in the citric acid crosslinked starch increased as the screw rotation decreased from 50 rpm to 10 rpm. When the 40% citric acid solution was used as the dry weight of the starch, the content of the starch was higher than that of Comparative Example 1 at a screw speed of 10 rpm.

[Example 2]

In order to investigate the effect of the reaction temperature of the continuous-circulation type heating reactor on the enzyme-resistant starch content of the crystalline citric acid crosslinked starch, the reaction mixture was heated to 130 ° C., 150 ° C., 170 ° C., and 190 ° C., The citric acid crosslinked starch was prepared by charging into a heating reactor at a rate of 100 g / min. The operating conditions of the continuous-circulation-type heating reactor and the enzyme-resistant starch content are shown in Table 3.

Effect of Reaction Temperature on the Enzyme Resistant Starch Content of Crystalline Citric Acid Crosslinked Starch in a Continuous Circulating Heating Reactor Crystalline reaction mixture Continuous circulation type heating reactor operating condition Enzyme resistant starch content
(%)
Citric acid concentration
(%) pH reaction
Temperature
(° C) Screw rotation speed
(rpm) Pass
collection
(time) 10 3.5 130 10 5 21.2 10 3.5 150 10 5 25.5 10 3.5 170 10 5 34.6 10 3.5 190 10 5 44.0 40 3.5 130 10 5 54.9 40 3.5 150 10 5 89.3 40 3.5 170 10 5 88.1 40 3.5 190 10 5 95.7

As shown in Table 3, in the case of the crystalline reaction mixture prepared using 10% citric acid solution, the enzyme resistant starch content in the citric acid crosslinked starch increased with increasing temperature. The reaction temperature was higher than that of the enzyme-resistant starch of Comparative Example using the same citric acid concentration at 190 ° C. On the other hand, the crystalline reaction mixture prepared using the 40% citric acid solution showed the maximum value of the enzyme-resistant starch at 150 ° C. and a slight decrease was observed while the reaction temperature was increased to 190 ° C. However, the enzyme resistant starch content Treated group showed high enzyme - resistant starch content.

[Example 3]

In order to investigate the effect of the circulating heating reactor passing rate on the change of the enzyme resistant starch content of the crystalline citric acid crosslinked starch, the number of times of passage of the continuous circulation heating reactor was changed from 1 to 9 times, The citric acid crosslinked starch was prepared by feeding into the reactor at a rate of 100 g / min. The operating conditions of the continuous-circulation-type heating reactor and the enzyme-resistant starch content are shown in Table 4.

Effects of Crystalline Citric Acid Crosslinked Starch on Enzyme Resistant Starch Contents in Continuous Circulating Heating Reactor Crystalline reaction mixture conditions Continuous circulation type heating reactor operating condition Enzyme resistant starch content
(%)
Citric acid concentration
(%) pH reaction
Temperature
(° C) Screw rotation speed
(rpm) Pass
collection
(time) 10 3.5 150 10 One 5.8 10 3.5 150 10 3 8.6 10 3.5 150 10 5 26.0 10 3.5 150 10 7 43.7 10 3.5 150 10 9 57.1 40 3.5 150 10 One 34.8 40 3.5 150 10 3 56.8 40 3.5 150 10 5 89.1 40 3.5 150 10 7 88.2 40 3.5 150 10 9 88.9

As shown in Table 4, in the case of the crystalline reaction mixture prepared using 10% citric acid solution, the content of enzyme resistant starch in the citric acid crosslinked starch increased with increasing the number of circulating heating reactor passing times. Especially, the enzyme resistant starch content increased rapidly after 3 passings. On the other hand, in the case of the crystalline reaction mixture prepared by using 40% citric acid solution, the number of passages in the continuous circulation type heating reactor was increased up to 5 times, and no significant difference was shown in the range of 5 to 9 passages.

[Example 4]

Amorphous citric acid To prepare crosslinked starch, the amorphous reaction mixture was fed through a hopper at a rate of 100 g / min into a continuous-circulation heating reactor and passed through a circulating heating reactor for 1-9 times to form amorphous citric acid crosslinked starch Respectively. The operating conditions of the continuous-circulation-type heating reactor and the enzyme-resistant starch content are shown in Table 5.

Effects of Amorphous Citric Acid Crosslinked Starch on Enzyme Resistant Starch Contents in Continuous Circulation Heating Reactor Passing Recovery Amorphous reaction mixture conditions Continuous circulation type heating reactor operating condition Enzyme resistant starch content
(%) Citric acid concentration
(%) pH reaction
Temperature
(° C) Screw rotation speed
(rpm) Pass
collection
(time) Insoluble Availability gun
(Insoluble + availability) 20 3.5 - - - 1.6 3.6 5.2 20 3.5 130 20 One 0.4 21.9 22.3 20 3.5 130 20 2 0.3 23.9 24.2 20 3.5 130 20 3 0.1 23.9 24.025.7 20 3.5 130 20 4 0.4 25.3 25.2 20 3.5 130 20 5 0.0 25.2 25.6 20 3.5 130 20 6 0.0 25.6 26.0 20 3.5 130 20 7 0.0 26.0 26.0 20 3.5 130 20 8 0.0 27.4 27.4 20 3.5 130 20 9 1.1 24.7 25.8

As shown in Table 5, when the amorphous citric acid crosslinked starch was prepared by using the amorphous reaction mixture prepared by using 20% citric acid solution, a rapid increase of the enzyme resistant starch content was observed in one cycle of the continuous circulation heating reactor, To 9 times, there was no significant difference in the number of passing times. On the other hand, the amorphous citric acid crosslinked starch had a lower content of enzyme resistant starch compared to the crystalline citric acid crosslinked starch, but the enzyme resistant starch of the amorphous citric acid crosslinked starch was composed of soluble enzyme resistant starch soluble in water.

[Example 5]

The appearance color characteristics of the indigestible citric acid crosslinked starch prepared in Comparative Example and Example 3 were measured and shown in FIG. 4 and Table 6.

Color Characteristics of Pre-crosslinked Citric Acid Bridged Oven and Continuous Circulating Heating Reactor sample Reactor Brightness (L ^* ) Redness (a ^* ) Yellowness (b ^* ) Comparative Example ^{1 )} Conversion Oven 85.0 2.1 19.9 Example 4 ^{2 )} Continuous circulation type
Heating reactor 94.6 -0.5 3.6 Natural starch - 96.8 -0.1 1.4

1) Reaction conditions: Crystalline reaction mixture prepared by using 40% citric acid solution (pH 3.5), reaction temperature 150 ℃, reaction time 5 hours

2) Reaction conditions: Crystalline reaction mixture prepared by using 40% citric acid solution (pH 3.5) at a reaction temperature of 150 ° C, a screw rotating speed of 10 rpm,

As can be seen above, the brightness of the ovariectable citric acid crosslinked starch reacted in the convection oven decreased and the yellowness increased. On the other hand, the indigestible citric acid crosslinked starch prepared by passing through a continuous circulation heating reactor showed no significant difference from the color characteristics of natural starch.

[Example 6]

The pH, reaction efficiency and acidity of citric acid crosslinking precursors were measured by using a continuous circulation heating reactor. The operating conditions and the measured values of the continuous circulation type heating reactor are shown in Table 7.

PH, reaction efficiency, and acidity of crystalline citric acid crosslinked starch Crystalline reaction mixture Continuous circulation type heating reactor operating condition
pH
Reaction efficiency
(%)
The intensity of acidity
(point) Citric acid concentration
(%) pH reaction
Temperature
(° C) Screw rotation speed
(rpm) Pass
collection
(time) 10 3.5 150 10 5 7.0 28.63 0 10 3.5 150 50 5 5.8 1.17 4 10 3.5 190 10 5 7.2 78.03 0 40 3.5 150 10 5 7.2 30.05 0 40 3.5 150 50 5 6.3 17.15 One 40 3.5 190 10 5 7.8 61.43 0

As can be seen in Table 6, except for the reaction at 50 rpm, there was no sour taste and the pH was more than 7.0. Thus, the indigestible citric acid crosslinked starch provided in this patent does not require a washing step after the reaction.

 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.

S1: Citric acid solution preparation step S2: Starch-citric acid mixture preparation step
S3: reaction mixture preparation step S4: step of inducing crosslinking reaction
S5: Completion phase

Claims (7)

a) preparing a citric acid solution having a pH of 1.0 to 6.5 and mixing it with starch, mixing the citric acid solution and the dried starch in a ratio of 1: 1 to prepare a starch-citric acid mixture;
b) drying the starch-citric acid mixture to a moisture content of 7.5% to prepare a reaction mixture; And
c) The above reaction mixture is repeatedly passed through a continuous circulation type heating reactor at a reaction temperature of 130 ° C. to 190 ° C. and a screw rotation speed of 10 to 50 rpm for 3 to 9 times to effect crosslinking reaction between starch molecules and citric acid To obtain a crystalline or amorphous indigestible citric acid crosslinked starch.
Process for the preparation of indigestible citric acid crosslinked starch. The method according to claim 1,
The step a)
Preparing a citric acid solution by mixing citric acid anhydride and sodium citrate in a weight ratio of 3: 1 and dissolving in purified water, wherein 0.1 to 0.4 kg of a citric acid mixture and 0.6 to 0.9 kg of purified water are mixed ≪ / RTI >
Process for the preparation of indigestible citric acid crosslinked starch. The method according to claim 1,
The step a)
1 kg of the citric acid solution and 1 kg of dried starch are put into a kneader and mixed for 20-30 minutes.
Process for the preparation of indigestible citric acid crosslinked starch. The method of claim 3,
The step b)
The starch-citric acid mixture mixed by the kneader was transferred to a stainless steel tray, followed by hot-air drying at 45 ° C so as to have a water content of 7.5% and pulverization to prepare a crystalline reaction mixture,
The step c)
Wherein the reaction mixture prepared in the step b) is repeatedly passed through the continuous circulation type heating reactor 3 to 9 times to obtain an indigestible citric acid crosslinked starch.
Process for the preparation of indigestible citric acid crosslinked starch. The method of claim 3,
The step b)
b-1) transferring the starch-citric acid mixture mixed by the kneader to a stainless steel tray, hot-air drying at 45 ° C to have a water content of 7.5%, and pulverizing to prepare a crystalline reaction mixture;
b-2) The crystalline reaction mixture is passed through an extruder, the temperature of which is gradually increased from the sample injection port area of the barrel to the injection area of the sample melt, while rotating the screw at 150 rpm, To a sample inlet of the barrel at a rate of 100 - 120 g / min to the extruder;
b-3) injecting purified water into the sample inlet of the barrel such that the water content of the crystalline reaction mixture is 25%; And
b-4) drying the extrudate passed through the circular nozzle of the extrusion molding machine at a temperature of 80 ° C in a hot air stream to have a water content of 7.5%, and pulverizing the resultant to prepare an amorphous reaction mixture.
Process for the preparation of indigestible citric acid crosslinked starch. The method according to claim 1,
The continuous-circulation-type heating reactor used in the step c) is characterized in that the extruder has a basic skeleton and a structure in which a discharge port and a forming nozzle are removed.
Process for the preparation of indigestible citric acid crosslinked starch.


delete

Images