KR100962588B1 - Manufacturing method of food compositon comprising sweet potato starch and guar gum - Google Patents

Abstract

The present invention relates to a food composition comprising sweet potato starch and guar gum and a process for producing the same.

According to the present invention, the rheological properties of sweet potato starch vary depending on the addition amount of guar gum, and by optimally controlling the content of guar gum added in the production of a food composition containing sweet potato starch, A food composition having rheological properties can be provided.

Sweet potato starch, guar gum, rheological properties

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a food composition containing sweet potato starch and guar gum,

The present invention relates to a food composition containing sweet potato starch and guar gum, and more particularly to a food composition containing sweet potato starch by examining the rheological properties of sweet potato starch, The present invention relates to a food composition having rheological properties suitable for various food characteristics by optimally controlling the content of guar gum added thereto and a method for producing the same.

Starch is a major ingredient in the food industry because of the large changes in rheological properties of starch when mixed with foodstuffs such as thickeners, gelling agents, bulking agents, water retention agents, fermentation energy sources and antisticky / sticky agents. The rheological properties of starch are strongly influenced by various factors such as starch type, amylose / pectin ratio, temperature, starch concentration, pH, and soluble low molecular weight solutes (salts, acids and sugars) And the presence and concentration of other components such as molecules (proteins and gums). Among them, gum is used as a functional additive in the food industry and plays an important role in modifying and controlling the rheological properties of starch. In various applications, it is very important to specifically control the rheological properties of starch, because it can control the production process and improve the stability and sensual properties of the food. Studies on the rheological properties of starch-gum mixture are very important for the functional studies on starch foods, since the gum greatly affects the rheological properties of starch.

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DISCLOSURE OF THE INVENTION The present invention has been made to overcome the above problems of the prior art, and it is a first object of the present invention to provide a sweet potato starch composition, which is prepared by thoroughly examining the rheological properties of sweet potato starch, The present invention provides a method of preparing a food composition having rheological properties suitable for various food characteristics by optimally controlling the content of guar gum.

In order to achieve the first object of the present invention,
Mixing guar gum so that the content of the guar gum is 0.4 to 0.6% by weight based on 100% by weight of a mixture of sweet potato starch and guar gum; Mixing 2 to 10 parts by weight of the mixture with 100 parts by weight of water and stirring at a stirring speed of 200 to 300 rpm at room temperature to prepare a paste; And agitating the paste at a stirring speed of 50 to 150 rpm while heating the paste at a temperature of 85 to 100 캜 for 20 to 40 minutes.

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According to the present invention, the rheological properties of sweet potato starch vary depending on the addition amount of guar gum, and by optimally controlling the content of guar gum added in the production of a food composition containing sweet potato starch, A food composition having rheological properties can be provided.

Hereinafter, the present invention will be described in more detail.

Gua is a black white-yellow powder with almost no odor and is a polysaccharide composed of galactomannan which can be prepared by crushing the endosperm of seeds of Cyamopsis tetragonolobus or extracting it with hot water or hot water. Generally, it is widely used for gua black foods and industrial use, which are highly viscous. For foods, it is mainly used for stabilizers of ice cream and dessert beverages. In addition, it is used for soups, sauces, , Canned foods, cake mixes, buttermix products, pickles, dietary fibers, and the like.

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Locust bean gum is also a white-yellowish white powder with a characteristic odor. It is extracted from the carob tree, which is a perennial evergreen soybean that is grown in the Mediterranean Sea, and is obtained by separating and purifying the endosperm. Locust bean gum is a chain-like polymer composed mainly of mannose and galactose (4: 1) and has a molecular weight of about 300,000 neutral polysaccharides. Locust bean gum is also used mainly as a stabilizer and thickener in foods, and is characterized by excellent acid resistance and alkali resistance. For example, it is used as a thickener and a stabilizer in stabilizers of ice cream and ice cream, bread, biscuits, snacks, sauces and sausages and sauces, mayonnaise, salad dressings and ketchup. Locust bean gum has to be roasted by raising the temperature to increase viscosity, but it differs in that it is hydrated even in gua black cold water.

The gelatinization properties of starch vary greatly depending on the type of gum added, as the starch-gum composition forms gels with noticeable viscoelastic properties by thickening and self-aggregating system. In relation to various food processing, the rheological properties of starch paste in starch-gum combination system are very important when the gum has functionality as a thickening agent of starch, because starch is accompanied by aging and aging in various food processing processes , And exhibit rheological properties characteristic of starch. In particular, amylopectin structure development or recrystallization processes between different molecular arrangements during long-term storage of starch-based food compositions are important property change factors.

Therefore, in the present invention, the influence of the addition of guar gum on the food composition containing sweet potato starch was analyzed, and as a result, the addition of galactomannan resulted in the viscosity and aging of the sweet potato starch paste, And the effect on the isothermal phenomenon was analyzed.

Specifically, the method for preparing a food composition of the present invention comprises mixing guar gum to make the content of guar gum to 0.4 to 0.6% by weight based on 100% by weight of a mixture of sweet potato starch and guar gum; Mixing 2 to 10 parts by weight of the mixture with 100 parts by weight of water and stirring at a stirring speed of 200 to 300 rpm at room temperature to prepare a paste; And stirring the paste at a stirring speed of 50 to 150 rpm while heating the paste at a temperature of 85 to 100 캜 for 20 to 40 minutes.

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As described above, the paste may be prepared by mixing 2 to 10 parts by weight of the mixture with respect to 100 parts by weight of water. If the content of water is too small in the production of the paste, the stirring may not be performed well, and if it is excessive, paste may not be formed.

Further, stirring in the paste production step is performed at a stirring speed of 200 to 300 rpm, and stirring in the heating step is preferably performed at a stirring speed of 50 to 150 rpm. When the stirring speed is slow, no paste is formed If the stirring speed is too fast, the starch structure may be destroyed.

Finally, the heating step is preferably performed at a temperature of 85 to 100 ° C. for 20 to 40 minutes. When the heating temperature is too low or the heating time is too short, the starch is not digested and paste is not formed And if the heating temperature is too high or the heating time is too long, the starch structure is completely broken and paste is not formed, which is not preferable.

Hereinafter, the present invention will be described in more detail with reference to the following examples, which should not be construed as limiting the scope of the present invention.

Example

Materials and Manufacture of Sweet Potato Starch Pastes

Sweet potato starch was purchased from Seo Young Food Co., Ltd. (Jeju Island, Korea), and guar gum and locust bean black Sigma Co. (St. Louis, MO, USA). The sweet potato starch had a moisture content of 13.2%, a ash content of 0.20% and a protein content of 0.58%, and an amylose content of 25.6%. Each of the sweet potato starch-guar gum mixture or sweet potato starch-locust bean gum mixture (total concentration 5 wt%) was prepared by mixing sweet potato starch with distilled water and adding guar gum and locust bean gum to 0 wt%, 0.2 wt% % And 0.6% by weight, respectively. Each sample was stirred slowly at room temperature for 1 hour and then heated in a 95 ° C water bath for 30 minutes with gentle stirring by a magnetic stirrer. At the heating end, a hot sample mixture was immediately added to the rheometer for rheological characterization.

Evaluation example . Rheological  Characterization

Static and dynamic shear rheological properties of sweet potato starch-guar gum mixture or sweet potato starch-locust bean gum mixtures were measured using a Carri-Med CSL ² 100 rheometer (TA Instruments, New Castle, DE, USA) , And a plate-plate (4 cm in diameter) shape with an interval of 500 mu m. Each sample was transferred to a rheometer at 25 ° C. The static shear (shear stress and shear rate) data were obtained at shear rates in the range of 1.0 - 1000 s ^-1 .

In order to show the static shear rheological properties of the samples, the data were applied to the power law model of Equation 1 and the Casson model of Equation 2, which are commonly used to measure the physical properties of food ingredients.

(Equation 1)

(Equation 2)

는 전단속도(단위: s^-1), K는 점조도(단위: Pa sⁿ), n은 유동성지수(단위없음), (K_c)²=η_c은 Casson 플라스틱 점성(η_c)이다. 식 2의 Casson 모델에 의하면 Casson 항복력은 K_oc를 제곱한 값에 의해 결정된다. K와 n의 질량으로 전단속도가 100s^-1일때의 겉보기 점도(η_a,100)가 계산된다. 더 나아가, 온도(25-70℃)가 고구마 전분-구아 검 혼합물 또는 고구마 전분-로커스트 빈 검 혼합물 겉보기 점도에 미치는 영향은 식 3의 Arrhenius 관계식에 의해 설명된다. Where σ is the shear force in Pa,

Is the shear rate (unit: s ^-1 ), K is the viscosity (unit: Pa s ⁿ ), n is the fluidity index (no unit), and (K _c ) ² = η _c is the Casson plastic viscosity (η _c ). According to the Casson model of Equation 2, the Casson yield strength is determined by the square of K _oc . The apparent viscosity (η _{a, 100} ) at the shear rate of 100 s ^-1 is calculated by the mass of K and n. Furthermore, the effect of temperature (25-70 ° C) on the apparent viscosity of the sweet potato starch-guar gum mixture or sweet potato starch-locust bean gum mixture is explained by the Arrhenius relationship of equation (3).

(Equation 3)

η _{a, 100} is a shear rate apparent viscosity (unit: Pa · s) at 100s ^-1 and, A is a constant (unit: Pa · s), and, T is the absolute temperature (unit: K), R is the gas constant ( 8.3144J · mol ^-1 · K ^-1 ), and Ea is the activation energy (unit: KJ · mol ^-1 ).

The dynamic shear characteristics were tested at 3% strain and 25 ° C, with a frequency range of 0.63-62.8 rad · s ^-1 , using the SAOS measurement method. Carri-Med software (version 3.1) was used to obtain experimental data and calculate storage modulus (G '), loss modulus (G ") and complex viscosity (η *). In order to stabilize the samples, all samples were left at 25 ° C for 5 minutes before measuring the rheological properties, and then the experiment was carried out. All rheological properties measurement experiments were repeated 3 times, and the experimental results are the average values of the above three experimental results.

Static shearing Rheological properties

Sweet potato starch-guar gum mixture or sweet potato starch locust bean experimental results for the shear rate and the shearing force of the gum mixture was well suited to both the rheological model, the power law model and the Casson model, as shown in Table 1, the coefficient of determination (R ² ) Was in the range of 0.93 to 0.99. All samples have low fluidity index (n) ranging from 0.30 to 0.36 and high shear-thinning behavior.

Sword shape density
(%) Apparent viscosity
(P s) Visibility
(Pa s ⁿ ) Liquidity index Yield stress
(Pa) Standard sample 0 1.11 ± 0.01 21.4 ± 0.91 0.36 ± 0.01 34.9 ± 1.26
Guar gum
0.2 1.24 ± 0.01 27.5 + -0.71 0.33 ± 0.01 42.0 ± 0.90 0.4 1.56 ± 0.01 37.1 ± 0.17 0.31 ± 0.00 56.3 ± 0.21 0.6 1.98 ± 0.01 49.1 ± 0.72 0.30 ± 0.00 78.3 ± 2.33
Locust bean gum
0.2 1.26 + - 0.01 23.5 ± 0.76 0.36 ± 0.00 36.1 ± 1.42 0.4 1.62 ± 0.01 32.1 ± 0.61 0.35 ± 0.00 51.2 ± 1.37 0.6 2.18 ± 0.01 44.7 ± 0.47 0.35 ± 0.00 72.7 ± 0.76

The n value of the sweet potato starch-guar gum mixture or sweet potato starch-locust bean gum mixture does not vary within the range of 0.2 to 0.6% of the grit concentration to the mixture. The n value of the sweet potato starch-guar gum mixture is 0.30 to 0.33, which is lower than that of the sweet potato starch-locust bean gum mixture having 0.35 to 0.36, from which the sweet potato starch-guar gum mixture It can be seen that the higher pseudoplastic flow appears to be due to the further expansion of the configuration of the guar gum.

The apparent viscosity (η _{a, 100} ), viscoelasticity (K) and yield stress (σ _oc ) in the power law model and the Casson model increased with increasing selenium concentration, and the sweet potato starch - guar gum mixture or sweet potato starch - The static shear properties of the locust bean gum mixture depend on the concentration of guar gum or locust bean gum and have a significant effect on guar gum or locust bean black starch-guar gum paste or sweet potato starch-locust bean gum paste. Similar results were obtained in previous studies of other starches such as corn starch, wheat starch, rice starch and guar gum or locust bean gum mixtures. Generally, the apparent viscosity and the K value of the sweet potato starch-guar gum mixture or sweet potato starch-locust bean gum mixture are higher than those of the standard sample, indicating that there is a high synergy effect with guar gum. The synergistic effect of the gum on the starch paste viscosity is due to the interaction of the starch extract with the gum, the increase of the gum concentration in the continuous phase of the medium, and the effect of the gum on the physical properties such as particle size and shape Reaction mechanism. It has been reported to be located in the black successive merchant amylose, and therefore the volume of these phases is reduced, which causes a dramatic increase in the concentration of sludge in the continuous phase. Therefore, it shows a very high viscosity. Comparison of viscoelasticity and yield stress of sweet potato starch - guar gum mixture and sweet potato starch - locust bean gum mixture showed that the consistency and yield stress of guar gum were higher than that of locust bean gum. And the dynamic shear rheological properties of. These results indicate that guar gum has synergistic effect because it has greater hydration ability and concentration than locust bean gum. Therefore, it can be concluded that the static flow characteristics of sweet potato starch - guar gum mixture depends on the static flow characteristics of guar gum. It is also affected by the shape and concentration of the sword.

Effect of Temperature on Apparent Viscosity

Since foods are processed and stored in a wide variety of temperature ranges, studies of the effects of temperature on the rheological properties of foods are generally very important. Figure 1 shows the viscosity induction curves of sweet potato starch pastes without gum added at different temperatures. ? Represents the measurement result at 25 占 폚,? Represents 40 占 폚,? Represents 55 占 폚, and? Represents 70 占 폚. Referring to FIG. 1, the apparent viscosity value decreases with increasing temperature. The temperature dependence of the apparent viscosity of the starch paste at a particular temperature can be determined by the Arrhenius model of equation (3). The Arrhenius temperature relationship has been confirmed experimentally with higher crystallinity coefficients in previous experiments on other starch - gum mixture pastes. Ea and the constant A value are higher in the range of 17.5 to 23.7 kJ mol ^-1 and 0.07 to 1.54 mPa s (R ² = 0.96-0.99). As shown in Table 2, this shows the temperature dependence of η _{a, 100} for all samples following the Arrhenius equation.

Sword shape density(%) A (mPa s) Ea (kJ mol ^-1 ) R ² Standard sample 0 0.07 23.7 0.97
Guar gum
0.2 0.17 21.9 0.98 0.4 0.72 19.4 0.96 0.6 1.54 17.5 0.99
Locust bean gum
0.2 0.25 20.9 0.98 0.4 0.30 21.1 0.98 0.6 0.54 21.2 0.97

The Ea value (17.5-21.9 kJ mole ^-1 ) of the sweet potato starch-guar gum mixture or sweet potato starch-locust bean gum mixture was lower than that of the standard sample (23.7 kJ mole ^-1 ) The viscosity of the gum mixture or sweet potato starch-locust bean gum mixture shows a lower temperature dependence in the gum concentration range study. It can also be seen that the addition of guar gum through these low Ea values improves the thermal stability of the sweet potato starch-guar gum mixture. The Ea value of the sweet potato starch - guar gum mixture changes with the increase of the gum concentration, while the Ea value of the sweet potato starch - locust bean gum mixture does not change. Furthermore, the Ea value of the sweet potato starch-guar gum mixture is lower than that of the sweet potato starch-locust bean gum mixture except at 0.2%. The lower Ea value in the presence of guar gum, as shown in Table 1, is related to its lower fluidity index (n). That is, the more the pseudoplasticity of the product, the smaller the effect of temperature on its apparent viscosity. From these observations it can be concluded that the viscosity of the sweet potato starch-guar gum mixture is less sensitive to temperature changes and that the Ea value is more dependent on sword concentration than the sweet potato starch-locust bean gum mixture.

Dynamic shear Rheological properties

Generally, starch particles are viewed as a composite material composed of amylopectin, an expanded particle present in amylose, a continuous biopolymer substrate, and thus its overall rheological characteristics are the viscoelasticity of branched or continuous phases, Is determined by the interaction between the phases. Figure 2 shows the log (G ', G ") vs. log ω of the mixture of sweet potato starch-guar gum and sweet potato starch-locust bean gum at 25 ° C. Each symbol ◯ represents 0% The storage elastic modulus (G ') and the loss elastic modulus (G ") values of the mixture were higher than those of the standard sample, and the storage elastic modulus (G') of the mixture was 0.2% (G ') was much higher than the loss modulus (G ") in all frequency ranges (0.63 ^- 62.8 rad s ^-1 ).

For comparison, the values of G ', G ", η * and tan δ of the sweet potato starch-guar gum mixture or sweet potato starch-locust bean gum mixture according to different gum concentrations at 6.28 rad s ^-1 were compared to those of Table 3 .

Sword shape density(%) G '(Pa) G "(Pa) 侶 * (Pa s) tan δ Standard sample 0 20.6 ± 0.36 8.50 0.39 0.74 ± 0.01 0.41 + 0.03
Guar gum
0.2 21.2 ± 0.24 9.84 0.27 0.78 + 0.02 0.46 ± 0.01 0.4 34.1 ± 0.14 14.8 ± 0.30 1.24 ± 0.01 0.43 + - 0.01 0.6 48.6 ± 0.74 19.9 ± 0.01 1.75 + 0.02 0.41 + - 0.01
Locust bean gum
0.2 25.3 ± 0.32 12.7 ± 0.21 0.94 + - 0.01 0.50 + - 0.01 0.4 29.2 ± 0.01 16.7 ± 0.11 1.12 ± 0.01 0.57 ± 0.01 0.6 39.6 ± 0.09 25.1 ± 0.49 1.56 ± 0.01 0.63 + - 0.01

In the dynamic rheological data of FIG. 2, the slope of the graph is positive, indicating that the mixture of sweet potato starch-guar gum mixture or sweet potato starch-locust bean gum acts like a weak gel, and the size of G ' (G ', G ", η *) of the sweet potato starch-guar gum mixture or sweet potato starch-locust bean gum mixture is much higher than that of the standard sample, The concentration increases as the sword concentration increases from 0% to 0.6%. This dependence on the gum concentration seems to be caused by the increase of viscoelasticity by adding guar gum and locust bean gum to the mixture of sweet potato starch-guar gum or sweet potato starch-locust bean gum mixture, respectively. At different concentrations (0.2-0.8%), the value of the dynamic index of the gum solution increases with increasing gum concentration, and the increase in viscoelasticity of the gum starch - guar gum mixture contributes to increasing the dynamic index of guava gum. The G 'value of the sweet potato starch-guar gum mixture is much higher than that of the sweet potato starch-locust bean gum mixture except for the mixture of 0.2%. As shown in Table 3, this results in a higher concentration of guar gum in the sweet potato starch- And it shows that it has a synergistic effect on the elastic effect. Improvement of G 'for 0.6% sweet potato starch-guar gum mixture can be explained by formation of weak elastic gel network at high sword concentration. In addition, the major difference between G 'and G "in the sweet potato starch-guar gum mixture is compared to the sweet potato starch-locust bean gum mixture, which is higher in the elasticity of the sweet potato starch-guar gum mixture The difference in the rheological properties between the sweet potato starch-guar gum mixture and the sweet potato starch-locust bean gum mixture indicates that its synergistic effect is influenced by the chemical structure of the continuous phase gel.

In describing the difference in viscoelastic behavior, the "tan δ", ie, the ratio of G "/ G ', is described as an element that characterizes the characteristic. As shown in Table 3, the tan δ value of the sweet potato starch-guar gum mixture ranges from 0.14 to 0.63 (Tan δ <1), indicating that the mixture is more elastic than viscous If the tan δ is in the range greater than 0.1, the sample is a weak gel specific to a typical viscoelastic gel, as mentioned above 0.6% guar gum (0.43-0.63) of the sweet potato starch-guar gum mixture was higher than that of the standard sample (0.41), indicating that the sweet potato starch-guar gum mixture was more elastic than the standard sample and dominant in the viscous properties The small change of G 'in the starch-gum mixture mechanism compared to G "indicates that the addition of gum does not affect the elastic properties of the starch paste. These results support that the deformation of the dynamic rheological properties is due to thermodynamically incompatible interactions between polymers of the same kind, which are strongly preferred over their interaction with other polymers. Therefore, the rheological behavior of the sweet potato starch-guar gum mixture is determined by the properties of the starch (permanent bond in the network) and the nature of the guar gum (temporary intermingling in the network).

The tan δ (0.41-0.46) of the sweet potato starch - guar gum mixture is much lower than the tan δ (0.50-0.63) of the sweet potato starch - locust bean gum mixture. This suggests that guar gum, And also contributes more to the weak structure network of the locust bean gum mixture. The tan δ value of the sweet potato starch-locust bean gum mixture increases with increasing gum concentration, which means that the effect of locust bean gum on the viscosity of sweet potato starch-locust bean gum mixture is even greater. Conversely, the tan δ value of the sweet potato starch-guar gum mixture decreases as the grit concentration increases from 0.2% to 0.6%, which implies an increase in the contribution of relative elasticity to viscoelasticity. Previous studies have shown that rice starch-guar gum mixtures with a gum concentration of 0.2-0.8% exhibit dynamic properties similar to those presented in Table 3. The G 'value (1.87 Pa) of guar gum solution in 6% gum solution was much higher than that of locust bean gum (0.84 Pa) when there was little difference in G "between guar gum and locust bean gum solution. The dynamic index of the sweet potato starch-guar gum mixture or sweet potato starch-locust bean gum mixture used in the experiment was much lower than that of other starches such as rice starch and corn starch and the experiment was performed in the same environment. As a result, the reduced tan δ values of the sweet potato starch-guar gum mixture at higher sludge concentrations, especially at 0.6%, were due to the fact that the elastic properties of guar gum alone were greater at higher concentrations (> 0.2%) compared with locust bean gum And the addition of guar gum seems to contribute to the increase in the elastic properties. From these observations, it was found that the sweet potato starch - guar gum mixture or sweet potato starch - locust bean gum mixture The value of tanδ showed that receives a great influence by the chemical structure of starch and gum, is dependent on the concentration of gum.

log (G ', G ") versus log ω data are shown in simple regression analysis, and slope and coefficient of determination (R ² ) are shown in Table 4.

Sword shape density(%) G 'slope
(Pa s) R ² G "
(Pa s) R ² Standard sample 0 0.24 ± 0.01 0.99 0.34 ± 0.01 0.99
Guar gum
0.2 0.26 ± 0.00 0.99 0.33 ± 0.00 0.99 0.4 0.25 0.00 0.99 0.30 0.01 0.99 0.6 0.25 0.01 0.99 0.27 ± 0.00 0.99
Locust bean gum
0.2 0.27 ± 0.01 0.99 0.31 ± 0.01 0.99 0.4 0.33 ± 0.00 0.99 0.32 ± 0.0 0.99 0.6 0.37 ± 0.00 0.99 0.29 ± 0.00 0.99

The slope of G '(0.25-0.37) and G "(0.27-0.33) of sweet potato starch - guar gum mixture or sweet potato starch - locust bean gum mixture has very high R ² value (0.99). The slope of G '(0.25-0.26) in the mixture is relatively lower than that of G "(0.27-0.37) in the sweet potato starch-locust bean gum mixture. These results indicate that the sweet potato starch - guar gum mixture samples are relatively more elastic than the sweet potato starch - locust bean gum mixture, and the G 'value of the sweet potato starch - locust bean gum mixture is much higher than that of the sweet potato starch - And is frequency dependent. The slope of G 'in the sweet potato starch - locust bean gum mixture increases with increasing sword concentration. There is also a large difference in the G 'slope of the standard sample (0% gum) and sweet potato starch-locust bean gum mixture. In conclusion, based on the above results, it was predicted that the dynamic rheological behavior of sweet potato starch-guar gum mixture was only related to the viscoelasticity of guar gum.

Figure 1 shows the viscosity induction curves of sweet potato starch pastes without gum added at different temperatures.

FIG. 2 shows the log (G ', G ") vs. log ω of the mixture of sweet potato starch-guar gum and sweet potato starch-locust bean gum at 25 ° C.

Claims (7)

delete delete Mixing guar gum so that the content of the guar gum is 0.4 to 0.6% by weight based on 100% by weight of a mixture of sweet potato starch and guar gum; Mixing 2 to 10 parts by weight of the mixture with 100 parts by weight of water and stirring at a stirring speed of 200 to 300 rpm at room temperature to prepare a paste; And And stirring the paste at a stirring speed of 50 to 150 rpm while heating the paste at a temperature of 85 to 100 캜 for 20 to 40 minutes. delete delete delete delete

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