A kind of high dietary fiber content resistant dextrin and preparation method thereof

Abstract

The present invention belongs to the technical field of functional sugars, and specifically relates to a resistant dextrin with high dietary fiber content and a preparation method thereof. The preparation method of the present invention comprises the following steps: mixing pea starch milk and liquefaction enzyme for liquefaction to obtain a liquefied liquid; the DE value of the liquefied liquid is 8-11%; the liquefied liquid is subjected to a molecular rearrangement reaction under acidic conditions to obtain a resistant dextrin; the dietary fiber mass content in the resistant dextrin is ≥93%. The present invention uses pea starch as a raw material, and after liquefaction, it is easy to obtain a crude dextrin liquid (liquefied liquid) with a suitable DE value. The present invention controls the DE value of the liquefied liquid to be 8-11%, and the obtained resistant dextrin has a high dietary fiber content and good digestibility.

Description

Technical Field

[0001] The invention belongs to the technical field of functional sugars, and particularly relates to a resistant dextrin with high dietary fiber content and a preparation method thereof. Background Art

[0002] Dietary fiber (a food nutrient that is not easily digested) can keep the intestines clean and has significant effects in reducing and preventing gastrointestinal diseases and controlling blood sugar. Dietary fiber includes soluble and insoluble dietary fiber. Insoluble dietary fiber has high viscosity, low solubility, and poor taste; while water-soluble dietary fiber has good solubility and good taste. It is widely used in the food industry and daily life, among which resistant dextrin is a representative product.

[0003] Resistant dextrin has excellent properties such as easy solubility, low viscosity, acid stability, freeze-thaw stability, low browning and storage stability. Resistant dextrin has α-1,3 glycosidic bonds and α-1,6 glycosidic bonds, as well as glucan and many irregular branched structures. It is difficult for human digestive enzymes to completely decompose the complex structure of resistant dextrin, thereby promoting basic metabolism such as intestinal peristalsis and blood circulation and stimulating intestinal probiotics to produce more short-chain fatty acids. Adding resistant dextrin as dietary fiber to food will not change the final quality of the product. In addition, resistant dextrin also has a series of good physiological functions and characteristics such as inhibiting the rapid rise of blood sugar levels after meals, regulating blood lipids, enhancing gastrointestinal function, regulating blood pressure, assisting in weight control, and low calories (only 0.5~1.4 kal / g), and has broad application prospects in processed foods.

[0004] At present, the production of resistant dextrin mainly uses corn starch, wheat starch or potato starch as raw materials, which are heated and decomposed at high temperature to become pyrodextrin, and then the pyrodextrin is dissolved in water, decomposed by enzymes, and then decolorized by activated carbon, desalted by ion exchange resins, chromatographic separation, and finally dried. However, after enzymatic hydrolysis, the dietary fiber content of the resistant dextrin is low, generally 80-85%, while the glucose and non-dietary fiber content is high. Summary of the invention

[0005] In view of this, the object of the present invention is to provide a resistant dextrin with high dietary fiber content and a preparation method thereof. The preparation method of the present invention increases the content of dietary fiber in the resistant dextrin.

[0006] The present invention provides a method for preparing resistant dextrin with high dietary fiber content, comprising the following steps:

[0007] Mixing pea starch milk and liquefaction enzyme to liquefy to obtain a liquefied liquid; the DE value of the liquefied liquid is 8-11%;

[0008] The liquefied liquid is subjected to a molecular rearrangement reaction under acidic conditions to obtain resistant dextrin; the mass content of dietary fiber in the resistant dextrin is ≥93%.

[0009] Preferably, the dosage of the liquefaction enzyme is 60-100 mL / ton based on the dry basis of the pea starch milk.

[0010] Preferably, the liquefaction temperature is 95-115° C. and the liquefaction time is 40-60 min.

[0011] Preferably, the molecular rearrangement reaction further includes enzyme inactivation, and the enzyme inactivation is acidic enzyme inactivation, and the acidic enzyme inactivation is: adjusting the pH value of the liquefied liquid to 3-4.

[0012] Preferably, the acidic condition of the molecular rearrangement reaction is pH = 1.5~2.

[0013] Preferably, the temperature of the molecular rearrangement reaction is 130-150° C. and the time is 1.5-2.5 h.

[0014] Preferably, the pea starch milk has a solid content of 30-40 wt % and a pH value of 5-6.

[0015] Preferably, after the molecular rearrangement reaction, the method further comprises: decolorizing, desalting, concentrating and drying the liquid obtained by the molecular rearrangement reaction in sequence; the decolorization is activated carbon decolorization, and the mass of the activated carbon in the activated carbon decolorization is 0.5-1% of the dry mass in the liquid.

[0016] Preferably, the desalination is ion exchange resin desalination, and the ion exchange resin desalination uses a combination of strong acid cation exchange resin D001-strong base anion exchange resin D202-strong acid cation exchange resin D001

[0017] The present invention also provides resistant dextrin with high dietary fiber content obtained by the preparation method described in the above technical scheme, wherein the mass content of dietary fiber in the resistant dextrin with high dietary fiber content is ≥93% and the DE value is ≤5%.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] The present invention provides a method for preparing resistant dextrin with high dietary fiber content, comprising the following steps: mixing pea starch milk and liquefaction enzyme for liquefaction to obtain a liquefied liquid; the DE value of the liquefied liquid is 8-11%; the liquefied liquid is subjected to molecular rearrangement reaction under acidic conditions to obtain resistant dextrin; the dietary fiber mass content in the resistant dextrin is ≥93%. The present invention controls the DE value of the liquefied liquid to be 8-11%. Within this DE value range, the process operation has high controllability and high repeatability, avoiding the problem of insufficient reaction degree or more monosaccharides causing violent reaction due to too low or too high DE value, and the prepared resistant dextrin has high dietary fiber content. The present invention uses pea starch as a raw material. Compared with corn starch and potato starch, the content of slowly digestible starch (SDS) in pea starch is relatively high. After liquefaction, it is easy to obtain a liquefied liquid with a suitable DE value. The resistant dextrin prepared by using the liquefied liquid has high dietary fiber content and good digestibility.

[0020] According to the preparation method of the present invention, the crude dextrin after liquefaction can be directly subjected to molecular rearrangement reaction to obtain resistant dextrin with high dietary fiber content, the dietary fiber mass content is ≥93%, the starch conversion rate is high, and there is no need to perform enzyme conversion and chromatographic separation on the resistant dextrin to make the components therein reach qualified indicators, and the content of small molecules such as glucose and the dietary fiber content are up to standard. In the prior art, generally, enzyme conversion is first used to hydrolyze macromolecules into small molecules, and then chromatographic separation is used to remove small molecules such as glucose to obtain digestion-resistant macromolecular dextrin. The resistant dextrin prepared by the present invention has a high dietary fiber content, and there is no need to remove small molecules additionally. The crude product liquid after the molecular rearrangement reaction is easy to purify, and the obtained product has high purity. The preparation method of the present invention is simple, has low energy consumption, low water consumption, and low cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0022] Figure 1 The flowchart of the preparation of resistant dextrin with high dietary fiber content in the embodiment. DETAILED DESCRIPTION

[0023] The present invention provides a method for preparing resistant dextrin with high dietary fiber content, comprising the following steps:

[0024] Mixing pea starch milk and liquefaction enzyme to liquefy to obtain a liquefied liquid; the DE value of the liquefied liquid is 8-11%;

[0025] The liquefied liquid is subjected to a molecular rearrangement reaction under acidic conditions to obtain resistant dextrin; the mass content of dietary fiber in the resistant dextrin is ≥93%.

[0026] In the present invention, unless otherwise specified, the materials and equipment used are commercially available products in the art.

[0027] The invention mixes pea starch milk and liquefaction enzyme to liquefy and obtain a liquefied liquid; the DE value of the liquefied liquid is 8-11%.

[0028] In the present invention, the solid content of the pea starch milk is preferably 30-40wt%, specifically 34wt%, 35wt% or 36wt%, and the pH value is preferably 5-6, specifically 5.2, 5.4, 5.5 or 5.6. In the pea starch milk slurrying process, it is preferred to use normal temperature tap water. The pea starch milk concentration of the present invention is convenient for direct molecular rearrangement reaction after liquefaction, and no secondary concentration adjustment is required; the pH value is the optimal pH range of the liquefaction enzyme, and it is easy to obtain a crude dextrin product with a suitable DE value.

[0029] In the present invention, the liquefying enzyme is preferably a high temperature α-amylase, and the dosage of the liquefying enzyme is preferably 60-100 mL / ton (i.e. 60-100 mL / T•DS) based on the dry basis of pea starch milk, and specifically 80 mL / ton. The high temperature α-amylase is preferably from Shandong Longkote Enzyme Preparation Co., Ltd., and the high temperature range is 90-120°C.

[0030] In the present invention, the liquefaction temperature is preferably 95-115°C, specifically 100°C, and the time is preferably 40-60 minutes, specifically 50 minutes. During the liquefaction process, starch granules absorb water and swell under the action of heat, and the bonding between starch molecules is weakened, resulting in partial disintegration of starch granules to form a uniform viscous liquid, i.e., dextrin. The liquefaction temperature and time described in the present invention facilitate the control of the DE value of the liquefied liquid to 8-11%.

[0031] In the present invention, the DE value of the liquefied liquid is preferably 9-10%, specifically 8%, 9.52%, 8.31%, 10.27%, 9.48%, 9.34% or 9.15%. The DE value (Dextrose Equivalent) refers to the percentage of reducing sugar (calculated as glucose) in dry matter, which is used to measure the degree of starch conversion to glucose. The DE value described in the present invention avoids the problem that the DE value is too low (less than 8) resulting in insufficient reaction or too high (greater than 11) resulting in more monosaccharides leading to violent reaction, and resistant dextrin with high dietary fiber content can be obtained. The liquefied liquid is a crude dextrin feed liquid.

[0032] After obtaining the liquefied liquid, the present invention performs a molecular rearrangement reaction on the liquefied liquid under acidic conditions to obtain the resistant dextrin; the dietary fiber mass content in the resistant dextrin is ≥93%.

[0033] In the present invention, the liquefied liquid is preferably subjected to enzyme inactivation before the molecular rearrangement reaction, and the enzyme inactivation is preferably acidic enzyme inactivation. The acidic enzyme inactivation is preferably: the pH value of the liquefied liquid is adjusted to 3-4, specifically 3.3, 3.4 or 3.5; the pH value regulator is preferably hydrochloric acid, and the present invention has no special requirements for the concentration of the hydrochloric acid.

[0034] In the present invention, the acidic conditions of the molecular rearrangement reaction are preferably pH = 1.5~2, specifically 1.5, 1.8 or 2. During the molecular rearrangement reaction, there is acid decomposition of dextrin, and the pH value of the present invention will not cause severe acid hydrolysis, produce too many small molecules, and will not cause the problem of insufficient acid hydrolysis of crude dextrin and insufficient polymerization. The pH value of the present invention is conducive to the molecular rearrangement reaction, and the dietary fiber content of the obtained resistant dextrin is high. During the molecular rearrangement reaction, the glycosidic bonds of the dextrin molecules are rearranged to form digestion-resistant bonds.

[0035] In the present invention, the molecular rearrangement reaction is preferably carried out under stirring and heating conditions, the heating temperature is preferably 130~150°C, specifically 140°C, the time is preferably 1.5~2.5h, specifically 2h; the stirring speed is preferably 100~200rpm, specifically 105rpm.

[0036] In the present invention, the molecular rearrangement reaction is preferably carried out in a reactor. The present invention preferably preheats the reactor before adding the enzyme-killed liquefied liquid. The preheating temperature is preferably 120-130°C, specifically 125°C, and the stabilization time is preferably 15-20 minutes.

[0037] In the present invention, the DE value of the crude resistant dextrin in the slurry obtained by the molecular rearrangement reaction is ≤5%, and the mass content of dietary fiber is ≥93% (on a dry basis).

[0038] In the present invention, after the molecular rearrangement reaction, the process preferably further comprises: decolorizing, desalting, concentrating and drying the liquid obtained by the molecular rearrangement reaction in sequence;

[0039] The decolorization is preferably activated carbon decolorization, and the activated carbon decolorization preferably comprises: mixing and heating the feed liquid obtained by the molecular rearrangement reaction and the activated carbon, and filtering to obtain the decolorized feed liquid; the mass of the activated carbon is preferably 0.5-1% of the dry mass in the feed liquid, specifically 0.8%; the heating temperature is preferably 78-82°C, specifically 80°C, and the insulation time is preferably 30-40 minutes;

[0040] The desalination is preferably ion exchange resin desalination, and the desalination preferably uses a combination of strong acid cation exchange resin D001-strong base anion exchange resin D202-strong acid cation exchange resin D001, the feed temperature is preferably 35-55°C, specifically 45°C or 50°C, and the feed rate is preferably 3-5BV / h, specifically 4BV / h;

[0041] The concentration temperature is preferably 50-60°C, specifically 55°C, and the pressure is preferably -0.1MPa. The solid content after concentration is preferably 75-80%, specifically 76%, 77%, 77.5%, 78% or 78.5%; the conductivity of the concentrated product is <50μs / cm, the transmittance is ≥95%, and the color is colorless or light yellow;

[0042] The drying is preferably vacuum drying, the drying temperature is preferably 100-110° C., and the moisture content of the product after drying is ≤5%.

[0043] The present invention also provides resistant dextrin with high dietary fiber content obtained by the preparation method described in the above technical scheme, wherein the dietary fiber mass content of the resistant dextrin with high dietary fiber content is ≥93% and the DE value is ≤5%.

[0044] The present invention provides a method for preparing resistant dextrin using pea starch. The resistant dextrin prepared using pea starch as raw material has a high dietary fiber content (≥93%) and good digestibility, thereby improving the starch conversion rate and expanding the application range of the product. The present invention has simple process innovation, accurately controls the liquefaction DE value, and can directly prepare resistant dextrin with a high dietary fiber content through molecular rearrangement reaction. Enzyme conversion and chromatography steps are not required, and the starch conversion rate is high, which reduces costs and improves efficiency.

[0045] In order to further illustrate the present invention, the high dietary fiber content resistant dextrin and the preparation method thereof provided by the present invention are described in detail below in conjunction with the accompanying drawings and examples, but they should not be construed as limiting the scope of protection of the present invention.

[0046] Figure 1 The flowchart of the preparation of resistant dextrin with high dietary fiber content in the embodiment is as follows: pea starch is slurried to obtain pea starch milk and then liquefied; the DE value of the liquefaction process is controlled to be 8-11; after the enzyme is inactivated, a molecular rearrangement reaction is performed, followed by decolorization, ion exchange desalination, concentration and drying to obtain resistant dextrin.

[0047] Example 1

[0048] (1) Slurry preparation: weigh 200 g pea starch and add tap water to prepare starch milk solids to 35% and pH to 5.5;

[0049] (2) Liquefaction: Add 80 mL / T•DS of high-temperature α-amylase to the starch milk and liquefy at 100 °C for 50 min to obtain the liquefied liquid, and then test the DE value index;

[0050] (3) Enzyme inactivation: Acidic enzyme inactivation method is used, and the pH value of the liquefied liquid is adjusted to 3.5 after liquefaction;

[0051] (4) Adjusting pH: adjusting the pH of the solution in step (3) to 1.8 with hydrochloric acid;

[0052] (5) Molecular rearrangement reaction: The high-temperature reactor was preheated to 125 °C and stabilized for 15 min. Then, the feed solution of step (4) was placed in the reactor and heated at 140 °C for 2 h. Stirring was started during the reaction at a speed of 150 rpm. After the reaction, a crude resistant dextrin feed solution was obtained, and the DE value and dietary fiber content were tested.

[0053] (6) Refining: Decolorization, ion exchange desalination, concentration and drying of the crude resistant dextrin liquid;

[0054] The decolorization process is as follows: adding 0.8% of the dry weight of activated carbon and keeping the temperature at 80°C for 30 minutes for decolorization;

[0055] Ion exchange desalination was performed by using a combination of D001 resin-D202-D001 resin, with an ion exchange temperature of 45 °C and a flow rate of 4 BV / h;

[0056] The concentration conditions are: concentration temperature 55 °C, pressure -0.1 MPa, solid content after concentration 75%, conductivity 23 μs / cm, transmittance 98%;

[0057] The drying conditions were: vacuum drying, pressure -0.1 MPa, temperature 100°C. Resistant dextrin powder was obtained by crushing, and the DE value, dietary fiber content and starch conversion rate were tested.

[0058] Example 2

[0059] (1) Slurry preparation: weigh 200 g pea starch and add tap water to prepare starch milk solids to 35% and pH to 5.6;

[0060] (2) Liquefaction: Add 60 mL / T•DS of high-temperature α-amylase to the starch milk and liquefy at 115 °C for 40 min to obtain the liquefied liquid, and then test the DE value index;

[0061] (3) Enzyme inactivation: Acidic enzyme inactivation method is used, and the pH value of the liquefied liquid is adjusted to 3.5 after liquefaction;

[0062] (4) Adjusting pH: adjusting the pH of the solution in step (3) to 1.8 with hydrochloric acid;

[0063] (5) Molecular rearrangement reaction: The high-temperature reactor was preheated to 120°C and stabilized for 20 min. Then, the liquid from step (4) was placed in the reactor and heated at 140°C for 2 h. Stirring was started during the reaction at a speed of 150 rpm. After the reaction, a crude resistant dextrin liquid was obtained, and the DE value and dietary fiber content were tested.

[0064] (6) Refining: Decolorization, ion exchange desalination, concentration and drying of the crude resistant dextrin liquid;

[0065] The decolorization process is as follows: adding 0.8% of the dry weight of activated carbon and keeping the temperature at 80°C for 30 minutes for decolorization;

[0066] Ion exchange desalination was performed by using a combination of D001 resin-D202-D001 resin, with an ion exchange temperature of 45 °C and a flow rate of 4 BV / h;

[0067] The concentration conditions are: concentration temperature 55 °C, pressure -0.1 MPa, solid content after concentration 75%, conductivity 32 μs / cm, transmittance 96.5%;

[0068] The drying conditions were: vacuum drying, pressure -0.1 MPa, temperature 100°C. Resistant dextrin powder was obtained by crushing, and the DE value, dietary fiber content and starch conversion rate were tested.

[0069] Example 3

[0070] (1) Slurry preparation: weigh 200 g pea starch and add tap water to prepare starch milk solids to 34% and pH to 5.4;

[0071] (2) Liquefaction: Add 100 mL / T•DS of high-temperature α-amylase to the starch milk and liquefy at 95 °C for 60 min to obtain the liquefied liquid, and then test the DE value index;

[0072] (3) Enzyme inactivation: Acidic enzyme inactivation method is used, and the pH value of the liquefied liquid is adjusted to 3.0 after liquefaction;

[0073] (4) Adjusting pH: adjusting the pH of the solution in step (3) to 1.8 with hydrochloric acid;

[0074] (5) Molecular rearrangement reaction: The high-temperature reactor was preheated to 125 °C and stabilized for 15 min. Then, the feed solution of step (4) was placed in the reactor and heated at 140 °C for 2 h. Stirring was started during the reaction at a speed of 150 rpm. After the reaction, a crude resistant dextrin feed solution was obtained, and the DE value and dietary fiber content were tested.

[0075] (6) Refining: Decolorization, ion exchange desalination, concentration and drying of the crude resistant dextrin liquid;

[0076] The decolorization process is as follows: adding 0.8% of activated carbon by dry weight and keeping the temperature at 80°C for 35 minutes for decolorization;

[0077] Ion exchange desalination is as follows: using a combination of D001 resin-D202-D001 resin for ion exchange desalination, controlling the ion exchange temperature at 50 °C and the flow rate at 4 BV / h;

[0078] The concentration conditions are: concentration temperature 55 °C, pressure -0.1 MPa, solid content after concentration 76%, conductivity 45 μs / cm, transmittance 96.6%;

[0079] The drying conditions were: vacuum drying, pressure -0.1 MPa, temperature 105°C. Resistant dextrin powder was obtained by crushing, and the DE value, dietary fiber content and starch conversion rate were tested.

[0080] Example 4

[0081] (1) Slurry preparation: weigh 200 g pea starch and add tap water to prepare starch milk solids to 34% and pH to 5.5;

[0082] (2) Liquefaction: Add 80 mL / T•DS of high-temperature α-amylase to the starch milk and liquefy at 100 °C for 50 min to obtain the liquefied liquid, and then test the DE value index;

[0083] (3) Enzyme inactivation: Acidic enzyme inactivation method is used, and the pH value of the liquefied liquid is adjusted to 3.4 after liquefaction;

[0084] (4) Adjusting pH: adjusting the pH of the solution in step (3) to 1.5 with hydrochloric acid;

[0085] (5) Molecular rearrangement reaction: The high-temperature reactor was preheated to 125 °C and stabilized for 15 min. Then, the feed solution of step (4) was placed in the reactor and heated at 140 °C for 2 h. Stirring was started during the reaction at a speed of 150 rpm. After the reaction, a crude resistant dextrin feed solution was obtained, and the DE value and dietary fiber content were tested.

[0086] (6) Refining: Decolorization, ion exchange desalination, concentration and drying of the crude resistant dextrin liquid;

[0087] The decolorization process is as follows: adding 1% of activated carbon by dry weight and keeping the temperature at 80°C for 40 minutes for decolorization;

[0088] Ion exchange desalination was performed by using a combination of D001 resin-D202-D001 resin, with an ion exchange temperature of 45 °C and a flow rate of 4 BV / h;

[0089] The concentration conditions are: concentration temperature 55 °C, pressure -0.1 MPa, solid content after concentration 78%, conductivity 48 μs / cm, transmittance 95.8%;

[0090] The drying conditions were: vacuum drying, pressure -0.1 MPa, temperature 110°C. Resistant dextrin powder was obtained by crushing, and the DE value, dietary fiber content and starch conversion rate were tested.

[0091] Example 5

[0092] (1) Slurry preparation: weigh 200 g pea starch and add tap water to prepare starch milk solids to 36% and pH to 5.2;

[0093] (2) Liquefaction: Add 80 mL / T•DS of high-temperature α-amylase to the starch milk and liquefy at 100 °C for 50 min to obtain the liquefied liquid, and then test the DE value index;

[0094] (3) Enzyme inactivation: Acidic enzyme inactivation method is used, and the pH value of the liquefied liquid is adjusted to 4 after liquefaction;

[0095] (4) Adjusting pH: adjusting the pH of the solution in step (3) to 2.0 with hydrochloric acid;

[0096] (5) Molecular rearrangement reaction: The high-temperature reactor was preheated to 125°C and stabilized for 15 min. Then, the feed solution of step (4) was placed in the reactor and heated at 140°C for 2 h. Stirring was started during the reaction at a speed of 150 rpm. After the reaction, a crude resistant dextrin feed solution was obtained. The DE value and dietary fiber content of the resistant dextrin index were tested.

[0097] (6) Refining: Decolorization, ion exchange desalination, concentration and drying of the crude resistant dextrin liquid;

[0098] The decolorization process is as follows: adding 0.5% of the dry weight of activated carbon and keeping the temperature at 82°C for 30 minutes for decolorization;

[0099] Ion exchange desalination was performed by using a combination of D001 resin-D202-D001 resin, with an ion exchange temperature of 45 °C and a flow rate of 4 BV / h;

[0100] The concentration conditions are as follows: concentration temperature 60 °C, pressure -0.1 MPa, solid content after concentration 80%, conductivity 45 μs / cm, transmittance 96.2%;

[0101] The drying conditions are: vacuum drying, pressure -0.1 MPa, temperature 105°C. Resistant dextrin powder is obtained by crushing, and the detection indicators DE value, dietary fiber content and starch conversion rate are tested.

[0102] Example 6

[0103] (1) Slurry preparation: weigh 200 g pea starch and add tap water to prepare starch milk solids to 35% and pH to 5.5;

[0104] (2) Liquefaction: Add 80 mL / T•DS of high-temperature α-amylase to the starch milk and liquefy at 100 °C for 50 min to obtain the liquefied liquid, and then test the DE value index;

[0105] (3) Enzyme inactivation: Acidic enzyme inactivation method is used, and the pH value of the liquefied liquid is adjusted to 3.6 after liquefaction;

[0106] (4) Adjusting pH: adjusting the pH value of the solution in step (3) to 1.8 with hydrochloric acid;

[0107] (5) Molecular rearrangement reaction: The high-temperature reactor was preheated to 125°C and stabilized for 15 min. Then, the feed solution of step (4) was placed in the reactor and heated at 130°C for 2.5 h. Stirring was started during the reaction at a speed of 100 rpm. After the reaction, a crude resistant dextrin feed solution was obtained. The DE value and dietary fiber content were tested.

[0108] (6) Refining: Decolorization, ion exchange desalination, concentration and drying of the crude resistant dextrin liquid;

[0109] The decolorization process is as follows: adding 1% of activated carbon by dry weight and keeping the temperature at 80°C for 40 minutes for decolorization;

[0110] Ion exchange desalination: Use a combination of D001 resin-D202-D001 resin for ion exchange desalination, with an ion exchange temperature of 45 °C and a flow rate of 4 BV / h;

[0111] The concentration conditions are: concentration temperature 55 °C, pressure -0.1 MPa, solid content after concentration 78.5%, conductivity 42 μs / cm, transmittance 96.4%;

[0112] The drying conditions are: vacuum drying, pressure -0.1 MPa, temperature 100°C. Resistant dextrin powder is obtained by crushing, and the detection indicators DE value, dietary fiber content and starch conversion rate are tested.

[0113] Example 7

[0114] (1) Slurry preparation: weigh 200 g pea starch and add tap water to prepare starch milk solids to 35% and pH to 5.5;

[0115] (2) Liquefaction: Add 80 mL / T•DS of high-temperature α-amylase to the starch milk and liquefy at 100 °C for 50 min to obtain the liquefied liquid, and then test the DE value index;

[0116] (3) Enzyme inactivation: Acidic enzyme inactivation method is used, and the pH value of the liquefied liquid is adjusted to 3.3 after liquefaction;

[0117] (4) Adjusting pH: adjusting the pH of the solution in step (3) to 1.8 with hydrochloric acid;

[0118] (5) Molecular rearrangement reaction: The high-temperature reactor was preheated to 125 °C and stabilized for 15 min. Then, the liquid from step (4) was placed in the reactor and heated at 150 °C for 1.5 h. Stirring was started during the reaction at a speed of 200 rpm. After the reaction, a crude resistant dextrin liquid was obtained. The DE value and dietary fiber content were tested.

[0119] (6) Refining: Decolorization, ion exchange desalination, concentration and drying of the crude resistant dextrin liquid;

[0120] The decolorization was performed by adding 1% of activated carbon on a dry basis and keeping the temperature at 82°C for 40 min for decolorization;

[0121] Ion exchange desalination was performed by using a combination of D001 resin-D202-D001 resin, with an ion exchange temperature of 45 °C and a flow rate of 4 BV / h;

[0122] The concentration conditions are: concentration temperature 55 °C, pressure -0.1 MPa, solid content after concentration 77.5%, conductivity 36 μs / cm, transmittance 96.2%;

[0123] The drying conditions were: vacuum drying, pressure -0.1 MPa, temperature 100°C. Resistant dextrin powder was obtained by crushing, and the DE value, dietary fiber content and starch conversion rate were tested.

[0124] Comparative Example 1

[0125] This comparative example is basically the same as Example 1, except that 50 mL / T•DS of high temperature α-amylase is added to the starch milk. After concentration, the solid content is 75.5%, the conductivity is 45 μs / cm, and the transmittance is 95%.

[0126] Comparative Example 2

[0127] This comparative example is basically the same as Example 3, except that 110 mL / T•DS of high temperature α-amylase is added to the starch milk. After concentration, the solid content is 76.5%, the conductivity is 32 μs / cm, and the transmittance is 96.4%.

[0128] Comparative Example 3

[0129] This comparative example is basically the same as Example 4, except that: in step (4), the pH value of the feed solution is adjusted to 1.4 with hydrochloric acid. After concentration, the solid content is 76.5%, the conductivity is 34 μs / cm, and the transmittance is 96.7%.

[0130] Comparative Example 4

[0131] This comparative example is basically the same as Example 5, except that: in step (4), the pH value of the feed solution is adjusted to 2.2 with hydrochloric acid. After concentration, the solid content is 79%, the conductivity is 32 μs / cm, and the transmittance is 95.3%.

[0132] Comparative Example 5

[0133] This comparative example is basically the same as Example 6, except that in step (5), the feed liquid is placed in a reaction kettle and heated at 120° C. After concentration, the solid content is 77.5%, the conductivity is 28 μs / cm, and the transmittance is 96.1%.

[0134] Comparative Example 6

[0135] This comparative example is basically the same as Example 7, except that in step (5), the feed liquid is placed in a reaction kettle and heated at 160° C. After concentration, the solid content is 79.5%, the conductivity is 31 μs / cm, and the transmittance is 95.8%.

[0136] Comparative Example 7

[0137] This comparative example is basically the same as Example 7, except that in step (5), the feed liquid is placed in a reaction kettle and heated at 160°C for 1 h. After concentration, the solid content is 78%, the conductivity is 26 μs / cm, and the transmittance is 95.4%.

[0138] Comparative Example 8

[0139] This comparative example is basically the same as Example 1, except that: in step (1), corn starch is weighed and concentrated to have a solid content of 75.3%, a conductivity of 26 μs / cm, and a light transmittance of 95.3%.

[0140] The indicators of Examples 1 to 7 and Comparative Examples 1 to 8 were tested: the DE value of the liquefied liquid sample (dextrin crude liquid) was tested, the DE value and dietary fiber mass content (on a dry basis) of the resistant dextrin crude liquid were tested, and the DE value, dietary fiber mass content and starch conversion rate of the finished resistant dextrin were tested. The test results are shown in Table 1 below:

[0141] Table 1 Test results of indicators of Examples 1 to 7 and Comparative Examples 1 to 8

[0142]

[0143] The starch conversion rate in Table 1 refers to the amount of dietary fiber converted from 1 ton of starch dry matter. Conversion rate = finished product mass * dietary fiber content / (starch dry matter mass).

[0144] As can be seen from Table 1, compared with Example 1, the amount of enzyme used in Comparative Example 1 is reduced, the DE value in the obtained liquefied liquid is low, the substrates such as glucose are insufficient during the anti-digestion reaction (molecular rearrangement reaction), the produced resistant dextrin is small, and the dietary fiber content is low; compared with Example 3, the amount of enzyme used in Comparative Example 2 is increased, the DE value in the obtained liquefied liquid is high, the substrates are more during the anti-digestion reaction, the reaction is violent, the resistant dextrin formed by polymerization is decomposed again, and the dietary fiber content is reduced; compared with Example 4, the pH value of the anti-digestion reaction in Comparative Example 3 is reduced, the degree of acid hydrolysis of the crude dextrin is high, the substrates are more during the polymerization process, the reaction is violent, the produced resistant dextrin is decomposed again, and the dietary fiber content is reduced; compared with Example 5, the pH value of the anti-digestion reaction in Comparative Example 4 is increased, the degree of acid hydrolysis of the crude dextrin during the anti-digestion reaction is reduced, the substrate content is small, The degree of polymerization is low and the dietary fiber content is low; compared with Example 6, Example 5 reduces the molecular rearrangement reaction temperature, the degree of polymerization is insufficient, the produced resistant dextrin is small, and the dietary fiber content is low; compared with Example 7, Example 6 increases the reaction temperature, and the resistant dextrin formed by polymerization is partially decomposed at high temperature, the produced resistant dextrin is small, and the dietary fiber content is low; compared with Example 6 at the same time, Example 7 increases the reaction temperature while reducing the reaction time, and the prepared resistant dextrin has a high DE value and a low dietary fiber content. This is because although the time is shortened, the temperature is too high and the reaction is violent and uncontrollable, and the obtained resistant dextrin is partially decomposed at high temperature; compared with Example 1, Example 8 uses corn starch, and the content of slowly digestible starch (SDS) in pea starch is higher than that in corn starch. Therefore, the dietary fiber mass content in the pea resistant dextrin in Example 1 is higher.

[0145] The resistant dextrins prepared in Examples 1 to 7 are excellent in DE value, dietary fiber content, etc., mainly because the reaction system of specific starch forms resistant dextrins with good digestibility and higher dietary fiber content.

[0146] Although the above-mentioned embodiments have made a detailed description of the present invention, they are only some embodiments of the present invention, rather than all embodiments. People can also obtain other embodiments based on the embodiments of the present invention without creative work, and these embodiments all fall within the scope of protection of the present invention.

Claims

1. A method for preparing resistant dextrin with high dietary fiber content, characterized in that: The following steps are involved: Mixing pea starch milk and liquefaction enzyme to liquefy to obtain a liquefied liquid; the DE value of the liquefied liquid is 8-11%; The liquefied liquid is subjected to a molecular rearrangement reaction under acidic conditions to obtain resistant dextrin; the mass content of dietary fiber in the resistant dextrin is ≥ 93%; The dosage of the liquefaction enzyme is 60-100 mL / ton based on the dry basis of the pea starch milk; The liquefaction temperature is 95-115°C and the time is 40-60 minutes; The acidic condition of the molecular rearrangement reaction is pH = 1.5~2; The temperature of the molecular rearrangement reaction is 130-150° C. and the time is 1.5-2.5 hours.

2. The preparation method according to claim 1, characterized in that: The molecular rearrangement reaction also includes enzyme inactivation, which is acidic enzyme inactivation. The acidic enzyme inactivation is: adjusting the pH value of the liquefied liquid to 3-4.

3. The preparation method according to claim 1, characterized in that: The pea starch milk has a solid content of 30-40wt% and a pH value of 5-6.

4. The preparation method according to claim 1, characterized in that: After the molecular rearrangement reaction, the method further comprises: sequentially decolorizing, desalting, concentrating and drying the liquid obtained by the molecular rearrangement reaction; the decolorization is activated carbon decolorization, and the mass of the activated carbon in the activated carbon decolorization is 0.5-1% of the dry basis mass in the liquid.

5. The preparation method according to claim 4, characterized in that: The desalination is ion exchange resin desalination, and the ion exchange resin desalination uses a combination of strong acid cation exchange resin D001-strong base anion exchange resin D202-strong acid cation exchange resin D001.

6. The high dietary fiber content resistant dextrin obtained by the preparation method according to any one of claims 1 to 5, characterized in that: The mass content of dietary fiber in the high dietary fiber content resistant dextrin is ≥93%, and the DE value is ≤5%.

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