Method for improving yield of resistant dextrin prepared by acid-thermal method

Abstract

The invention belongs to the technical field of preparation of resistant dextrin, and particularly relates to a method for improving the yield of resistant dextrin prepared by an acid-thermal method. Comprising the following steps: treating starch in plasma for 30-150 seconds to obtain modified starch; the plasma is obtained under the conditions of 25 DEG C to 40 DEG C and 60 V to 100 V; and treating the modified starch by adopting an acid-heat method, and purifying to prepare the resistant dextrin. Before the acid-heat method, the starch is subjected to plasma treatment, so that alpha-1, 4 glucosidic bonds in starch molecules can be destroyed, more short-chain dextrin can be formed, amorphous regions of starch particles are preferentially degraded, crystalline regions are partially destroyed, more reaction sites are exposed, and molecular rearrangement is promoted to form beta-1, 2 or beta-1, 2 or beta-1, 2 or beta-1, 2 or beta-1, 2 or beta-1, 2 or beta-1, 2 or beta-1, 2 or beta-1, 2 or beta-1, 2 or beta-1, 2 or beta-1, 2 or beta-1, 4 glucosidic bonds with higher resistance. 3 glycosidic bonds. The yield of the resistant dextrin prepared by the method disclosed by the invention is 83.12%.

Description

Technical Field

[0001] The present invention belongs to the technical field of resistant dextrin preparation, and particularly relates to a method for improving the yield of resistant dextrin prepared by the acid-heat method. Background Art

[0002] Resistant dextrin is a low-calorie glucan prepared by processes such as acid hydrolysis, enzymatic hydrolysis, and purification of starch. It is a dietary fiber with a low molecular weight and soluble in water. Its molecular backbone is mainly composed of α-1,4 and α-1,6 glycosidic bonds. Through acid heat treatment and enzyme modification, non-digestible glycosidic bonds are introduced, and the generated α-1,2 and α-1,3 glycosidic bonds endow it with the property of resisting digestive enzyme hydrolysis. It is not absorbed in the small intestine of the human body and can enter the large intestine intact to play physiological functions. Resistant dextrin has a low viscosity, is easy to absorb, and has important physiological functions such as blood glucose regulation, promoting intestinal peristalsis, and controlling body weight. Resistant dextrin is widely used in dairy products, flour products, and health products.

[0003] At present, the preparation process of resistant dextrin shows a diversified development trend. Resistant dextrin was first developed by Matsutani Chemical Industry Co., Ltd. in Japan in the 1980s. Starch is heated and decomposed in acid at 130°C to 180°C to become roasted dextrin, and then made into indigestible dextrin through processes such as enzymatic hydrolysis, decolorization, desalting, and separation and purification. However, the traditional acid-heat method has high energy consumption, large pollution, and is prone to by-products. Many subsequent preparation processes are improvements and optimizations based on the acid-heat method. Huang Jihong used the closed roller method to create a high-pressure environment, thereby effectively increasing the content of resistant dextrin in the product. However, further purification of the sample, such as decolorization and impurity removal, still needs further research. Based on considerations of health value, researchers have focused on and utilized the structure and physicochemical properties of various coarse grain starches for the development and application of resistant dextrin. For example, sorghum starch, buckwheat starch, etc. are used as raw materials to prepare resistant dextrin. The prepared resistant dextrin is mostly in the form of blocks or irregular structures formed by aggregation of small molecules, with increased water solubility and the formation of new digestion-resistant glycosidic bonds. It can be seen that the current research mainly focuses on the development and utilization of new starch resources, the optimization of the acid-heat process, and the purification process of resistant dextrin. However, the optimization of the acid-heat preparation process mentioned above has problems such as complex process, long preparation time, high energy consumption, and the yield of resistant dextrin is relatively low, about 62.2%. Summary of the Invention

[0004] In order to solve the above technical problems, the present invention provides a method for improving the yield of resistant dextrin prepared by the acid-heat method. The plasma-assisted acid-heat method is used to prepare resistant dextrin, effectively improving the starch conversion rate and the purity of resistant dextrin.

[0005] In order to achieve the above object, the specific scheme of the present invention is as follows.

[0006] A method for improving the yield of resistant dextrin prepared by the acid-heat method, comprising the following steps: The starch is treated in plasma for 30 s to 150 s to obtain modified starch; the plasma is obtained under the conditions of 25 °C to 40 °C and 60 V to 100 V; After the modified starch is treated by the acid-heat method, it is purified to prepare resistant dextrin.

[0007] In the present invention, the pretreatment of starch by plasma can preferentially degrade the amorphous region of starch granules, and at the same time partially destroy the crystalline region, exposing more reactive site pairs, promoting molecular rearrangement to form β-1,2 or β-1,3 glycosidic bonds with stronger resistance, thereby increasing the yield of resistant dextrin prepared by the subsequent acid-heat method.

[0008] In another preferred embodiment, the time of the plasma treatment is 30 s to 40 s; the plasma is obtained under the conditions of 30 °C to 40 °C and 85 V to 95 V.

[0009] In another preferred embodiment, the specific process of the plasma treatment is as follows: The starch is placed in an insulating medium, and under the conditions of a voltage of 85 V to 95 V and a temperature of 30 °C to 40 °C, the reaction medium is ionized by an electrode to obtain plasma, and the starch is treated by the plasma.

[0010] In another preferred embodiment, the reaction medium is air; the insulating medium is quartz glass.

[0011] In another preferred embodiment, the starch is corn starch.

[0012] In another preferred embodiment, the specific process of the acid-heat method is as follows: The modified starch is acidified at 160 °C to 170 °C for 50 min to 90 min to obtain pyrodextrin; After the pyrodextrin is enzymatically hydrolyzed, a crude product of resistant dextrin containing α-1,2 glycosidic bonds and α-1,3 glycosidic bonds is generated, and the crude product of resistant dextrin is purified to obtain resistant dextrin.

[0013] In another preferred embodiment, the acidifying reagent is hydrochloric acid with a mass percentage of 0.5% to 1%; the mass of the hydrochloric acid accounts for 6% to 14% of the mass of the modified starch.

[0014] In another preferred embodiment, the specific process of the enzymatic hydrolysis is as follows: After the pyrodextrin is mixed with water, the pH value is adjusted to 6 to 6.5, α-amylase is added, and enzymatic hydrolysis is carried out at 92 °C to 94 °C for 2 h to 2.5 h; the pH value is adjusted to 4.5 to 5, glucoamylase is added, and enzymatic hydrolysis is carried out at 56 °C to 58 °C for 2 h to 2.5 h; the mass of the α-amylase accounts for 0.4% to 1% of the pyrodextrin; The mass of the amyloglucosidase accounts for 0.3% - 0.5% of the dextrin.

[0015] In another preferred embodiment, the specific purification process is as follows: After acid-heat treatment, inactivate, centrifuge to obtain the supernatant, concentrate it, then perform alcohol precipitation, and take the supernatant for drying.

[0016] In another preferred embodiment, the reagent used for alcohol precipitation is ethanol with a mass percentage of 95% - 98%.

[0017] Compared with the prior art, the present invention has the following effects: After treating starch plasma at 25°C - 40°C with a voltage of 60V - 100V for 30s - 150s, the present invention can preferentially degrade the amorphous region of starch granules, and at the same time partially destroy the crystalline region, exposing more reaction sites, promoting molecular rearrangement to form more resistant β-1,2 or β-1,3 glycosidic bonds. In addition, the high-energy particles and active free radicals generated by the plasma bombard the surface of starch granules, breaking the α-1,4 glycosidic bonds in starch molecules to form more short-chain dextrins, which is beneficial to the formation of resistant structures. Treating the modified starch after plasma treatment with the acid-heat method can effectively increase the yield of resistant dextrin, up to 83.12%. Compared with the yield of 62.2% in the prior art, the yield of resistant dextrin in the present invention has been effectively improved, and the entire preparation process is simple and has low energy consumption, providing a new way for improving the yield of resistant dextrin. Description of the Drawings

[0018] Figure 1 Shows the effect of different plasma voltages on the yield of resistant dextrin.

[0019] Figure 2 Shows the effect of different plasma treatment times on the yield of resistant dextrin.

[0020] Figure 3 Shows the effect of different acid-heat treatment times on the yield of resistant dextrin.

[0021] Figure 4 Shows the effect of different hydrochloric acid addition amounts on the yield of resistant dextrin.

[0022] Figure 5 Shows the effect of different α-amylase hydrolysis temperatures on the yield of resistant dextrin. Detailed Embodiments

[0023] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts belong to the scope of protection of the present invention.

[0024] It should be noted that the professional terms used in the present invention are only for the purpose of describing specific embodiments and are not intended to limit the protection scope of the present invention. Unless otherwise specifically stated, various raw materials, reagents, instruments, and equipment used in the following embodiments of the present invention can be obtained through market purchases or prepared by existing methods.

[0025] α-Amylase and glucoamylase were purchased from Shanghai Yuanye Bio-Technology Co., Ltd. The enzyme activity of α-amylase was 2×10 4 U / g, and the enzyme activity of glucoamylase was 1×10 6 U / g; the starch in the following embodiments was corn starch. The dielectric barrier discharge plasma device was purchased from Suman Plasma Technology Co., Ltd., and the model was CTF-2000R.

[0026] 1. Plasma pretreatment Air was used as the reaction medium. A dielectric barrier discharge plasma device was used, and a circular quartz glass with a diameter of 5 cm was selected as the insulating medium, and the electrode spacing was set at 8 mm. The specific operation process was as follows: Weigh 4 g of corn starch and evenly spread it in the quartz glass groove. Subsequently, plasma treatment was carried out for 30 s under the conditions of a constant current of 0.8 A, a voltage of 90 V, and a temperature of 40 °C. After the treatment was completed, the modified corn starch was collected and stored in a sealed bag for standby.

[0027] 2. Preparation of resistant dextrin Weigh the modified corn starch, add hydrochloric acid at 6% of the starch mass, and carry out acidification at 170 °C for 60 min. Then, it was placed in an oven at 55 °C for pre-drying until the moisture content was less than 5%, and thus resistant dextrin was obtained.

[0028] Dissolve dextrin in distilled water with a mass three times its volume, adjust the pH to 6 with 0.1 mol / L NaOH solution, add α-amylase at 0.4% of the dextrin mass, and stir magnetically at 94 °C for 2 h; adjust the pH to 4.5 with 0.1 mol / L hydrochloric acid solution, add amyloglucosidase at 0.3% of the dextrin mass, stir magnetically at 56 °C for 2 h, inactivate at 100 °C for 10 min, cool to room temperature, centrifuge at 4000 r / min for 15 min, take the supernatant, heat-concentrate it to one-fourth of the supernatant volume in an 80 °C water bath, add 4 times the volume of 95% ethanol for alcohol precipitation twice, stir evenly, let stand for 2 h, and then remove the supernatant. Take a sample, dry it to a constant weight at 105 °C, calculate the resistant dextrin yield, and the formula for calculating the resistant dextrin yield is as follows.

[0029] ; Among them, m1 is the mass of the dried substance, and m2 is the mass of corn starch.

[0030] 3. Condition optimization 1) Single-factor experiment Through single-factor experiments, investigate the effects of plasma time (30 s, 60 s, 90 s, 120 s, 150 s), plasma voltage (60 V, 70 V, 80 V, 90 V, 100 V), hydrochloric acid addition amount (6%, 8%, 10%, 12%, 14%), acid-heat time (50 min, 60 min, 70 min, 80 min, 90 min), and α-amylase hydrolysis temperature (90 °C, 92 °C, 94 °C, 96 °C, 98 °C) on the resistant dextrin yield, and determine the optimal process conditions.

[0031] 2) Orthogonal experiment On the basis of single-factor experiments, taking plasma time, plasma voltage, hydrochloric acid addition amount, and α-amylase hydrolysis temperature as independent variables, and the resistant dextrin yield as the evaluation index, use the L9(3 4 ) orthogonal experiment to optimize and obtain the best preparation process, and design the preparation process level table as shown in Table 1.

[0032] Table 1 Orthogonal experiment factor level table 4. Results 4.1 Single-factor experiment (1) Effect of plasma voltage on the resistant dextrin yield The results are as Figure 1 shown. From Figure 1It can be seen that as the plasma voltage increases, the yield of resistant dextrin shows an increasing trend. The amorphous region of starch granules degrades preferentially, and at the same time, part of the crystalline region is damaged, exposing more reaction sites, promoting molecular rearrangement to form more resistant β-1,2 or β-1,3 glycosidic bonds. When the voltage is 70V, its yield reaches the maximum value of 76.20%. When the treatment voltage exceeds 70V, the yield of resistant dextrin gradually decreases. This may be due to the enhanced plasma treatment intensity inducing excessive etching and damage on the starch surface, as well as the rearrangement of sheet molecular chains and starch in a disordered state, reducing the sensitivity of starch molecules to enzymatic hydrolysis. Therefore, considering all factors, it is appropriate to select a plasma voltage of 70V.

[0033] (2)Effect of plasma time on the yield of resistant dextrin The results are as Figure 2 shown. It can be seen from Figure 2 that as the time increases, the yield of resistant dextrin gradually increases. This may be because the high-energy particles (electrons, ions) and active free radicals generated by the plasma bombard the surface of starch granules, breaking the α-1,4 glycosidic bonds in starch molecules and forming more short-chain dextrins, which is beneficial to the formation of resistant structures. When the treatment time is 90s, the yield of resistant dextrin reaches the maximum value of 75.60%. When the treatment time exceeds 90s, the yield of resistant dextrin gradually decreases. This may be due to the continuous high-energy bombardment causing the molecular chains of resistant dextrin to further break to the level of oligosaccharides or even monosaccharides, greatly reducing the anti-digestive properties. Therefore, considering all factors, it is appropriate to select a plasma time of 90s.

[0034] (3)Effect of acid-heat time on the yield of resistant dextrin The results are as Figure 3 shown. It can be seen from Figure 3 that when the acid-heat time is short, due to the acid-catalyzed cleavage of α-1,4 and α-1,6 glycosidic bonds in starch molecules, the starch granules depolymerize, resulting in the gradual accumulation of resistant dextrin products. At 70 min, the yield of resistant dextrin reaches the maximum of 82.6%. Subsequently, the yield of resistant dextrin gradually decreases, probably because of the continuous action of acid-heat conditions, and the resistant dextrin itself is further hydrolyzed into smaller molecules such as maltose and glucose, with a reduction in resistant structures. Therefore, considering all factors, it is appropriate to select an acid-heat time of 70 min.

[0035] (4)Effect of hydrochloric acid addition amount on the yield of resistant dextrin The results are as Figure 4 shown. It can be seen from Figure 4It can be seen that as the addition amount of hydrochloric acid increases, the yield of resistant dextrin shows a trend of first increasing and then decreasing. When the addition amount of hydrochloric acid is low, the acidic condition promotes the hydrolysis of α-1,4 and α-1,6 glycosidic bonds in starch molecules, forming short-chain dextrins. At this time, the reaction mainly stays in the starch depolymerization stage, generating resistant dextrins with specific molecular weights and branched structures, thus increasing the yield. When the addition amount of hydrochloric acid is 10% of the modified corn starch, the yield of resistant dextrin is as high as 75.4%. After the addition amount of hydrochloric acid further increases, the molecular weight of resistant dextrin further decreases, generating small molecule monosaccharides or disaccharides such as maltose and glucose. These products do not have anti-digestive properties, resulting in a decrease in yield. Therefore, considering all factors, it is appropriate to choose the addition amount of hydrochloric acid to be 10% of the mass of modified corn starch.

[0036] (5)Effect of α-amylase hydrolysis temperature on the yield of resistant dextrin The results are as Figure 5 shown. It can be seen from Figure 5 the figure that at 92°C - 94°C, the yield of resistant dextrin shows an upward trend. When the temperature increases, the collision frequency between the enzyme and starch increases, and the gelatinization degree of starch increases with the increase of temperature, exposing more α-1,4 glycosidic bond sites, which is convenient for the enzyme to cut efficiently and generate products. When the action temperature of α-amylase is 94°C, the highest yield of resistant dextrin is obtained, reaching 75.10%. After the action temperature of α-amylase is higher than 94°C, the yield of resistant dextrin gradually decreases. It may be because the three-dimensional structure of the enzyme protein is damaged at high temperature, affecting the activity of high-temperature α-amylase, resulting in a decrease in the yield of resistant dextrin. Therefore, considering all factors, it is appropriate to choose the hydrolysis temperature of high-temperature α-amylase to be 94°C.

[0037] 4.2 Data analysis of orthogonal experiment on resistant dextrin The analysis of the orthogonal experiment results is shown in Table 2. It can be seen from the magnitude of the R value that the order of factors affecting the yield is addition amount of hydrochloric acid > plasma voltage > plasma time > acid-heat time. The optimal combination affecting the yield is A3B2C3D1, that is, the addition amount of hydrochloric acid is 12%, the plasma voltage is 80V, the plasma time is 90s, and the acid-heat time is 60min.

[0038] Table 2 Analysis of orthogonal experiment results Note: " / " indicates that this item is not included.

[0039] 4.3 Verification experiment After verification tests, the yield of resistant dextrin was (83.12 ± 0.98)%, which was higher than any of the results in the orthogonal tests. It was further determined that the optimal process for preparing resistant dextrin by plasma-assisted acid-heat method was as follows: the hydrochloric acid addition amount was 12%, the plasma voltage was 80 V, the plasma time was 90 s, the acid-heat time was 60 min, and the enzymatic hydrolysis temperature of α-amylase was 94 °C. The yield of resistant dextrin without plasma treatment under the optimized conditions was 72%.

[0040] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalent technologies, the present invention is also intended to include these changes and modifications therein.

Claims

1. A method for improving the yield of resistant dextrin prepared by the acid-heat method, characterized in that The following steps are involved: Treating starch in plasma for 30s to 150s to obtain modified starch; The plasma is obtained under the conditions of 25°C to 40°C and 60V to 100V; The modified starch is treated with an acid-heat method and then purified to obtain resistant dextrin.

2. The method for increasing the yield of resistant dextrin prepared by the acid-heat method according to claim 1, characterized in that The plasma treatment time is 30s-40s; the plasma is obtained under the conditions of 30°C-40°C and 85V-95V.

3. The method for improving the yield of resistant dextrin prepared by the acid-heat method according to claim 2, characterized in that: The specific process of the plasma treatment is as follows: The starch is placed in an insulating medium, and under the conditions of a voltage of 85V~95V and a temperature of 30℃~40℃, the reaction medium is ionized by an electrode to obtain plasma, and the starch is treated by the plasma.

4. The method for increasing the yield of resistant dextrin prepared by the acid-heat method according to claim 2, wherein The reaction medium is air; the insulating medium is quartz glass.

5. The method for improving the yield of resistant dextrin prepared by acid-thermal method according to claim 1, characterized in that: The starch is corn starch.

6. The method for improving the yield of resistant dextrin prepared by the acid-heat method according to claim 1, characterized in that, The specific process of the acid-heat method is as follows: Acidifying the modified starch at 160°C to 170°C for 50 min to 90 min to obtain pyrodextrin; Pyrodextrin is enzymatically hydrolyzed to generate crude resistant dextrin containing α-1,2 glycosidic bonds and α-1,3 glycosidic bonds.

7. The method for increasing the yield of resistant dextrin prepared by the acid-heat method according to claim 6, characterized in that, The acidification reagent used is 0.5% to 1% hydrochloric acid by mass; the mass of the hydrochloric acid accounts for 6% to 14% of the mass of the modified starch.

8. The method for increasing the yield of resistant dextrin prepared by the acid-heat method according to claim 6, characterized in that, The specific process of the enzymatic hydrolysis is as follows: After mixing pyrodextrin with water, adjust the pH value to 6-6.5, add α-amylase, and perform enzymatic hydrolysis at 92-94°C for 2h-2.5h; adjust the pH value to 4.5-5, add amyloglucosidase, and perform enzymatic hydrolysis at 56-58°C for 2h-2.5h; The mass of the α-amylase accounts for 0.4% to 1% of the pyrodextrin; The mass of the amyloglucosidase accounts for 0.3% to 0.5% of the pyrodextrin.

9. The method for improving the yield of resistant dextrin prepared by the acid-heat method according to claim 1, wherein The specific process of the purification is as follows: After acid-heat treatment, the product was inactivated, centrifuged, concentrated, and precipitated with alcohol, and the supernatant was dried.

10. The method for increasing the yield of resistant dextrin prepared by the acid-heat method according to claim 9, characterized in that, The reagent used for the alcohol precipitation is 95% to 98% ethanol by mass.

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