Preparation method for maltodextrin

Abstract

The present invention belongs to the technical field of developing carbohydrate ingredients for foods for special dietary uses. Disclosed is a preparation method for maltodextrin. The present invention utilizes starch as a raw material, and utilizes dry thermal amorphization technology to disaggregate the molecular chain of starch and to improve the solid content of a reaction system, thereby reducing the viscosity of the system; then by means of the combination of polyethylene glycol precipitation fractionation, alcohol complexation fractionation and membrane interception fractionation, narrows the range of molecular weight distribution of maltodextrin; and finally performs batch drying to obtain a maltodextrin product having uniformly distributed degrees of polymerization, wherein the yield of maltodextrin can reach 80% or above. Different fractionated maltodextrin components collected and obtained in the present invention have stable functions and properties, thereby achieving great application prospects in the fields of functional ingredients of foods for special dietary uses, embedding carriers for flavor substances and food additives. In addition, the technical solution of the present invention can improve the production efficiency of maltodextrin, and reduce the drying cost and energy consumption, thus achieving significant advantages in environmental protection.

Description

A preparation method of maltodextrin Technical Field

[0001] The invention relates to a preparation method of maltodextrin, and belongs to the technical field of development of special dietary carbohydrate ingredients. Background Art

[0002] Maltodextrin refers to a starch hydrolysis product with a degree of hydrolysis (DE) of less than 20 obtained by acid or enzymatic treatment using starch as raw material. Its main components are dextrin with a degree of polymerization (DP) above 10 and a small amount of oligosaccharides with a degree of polymerization below 10. It has the characteristics of a wide molecular weight distribution and a large dispersity coefficient.

[0003] Currently, maltodextrin is commonly produced using the processes of jet liquefaction and hydrothermal gelatinization. Jet liquefaction can achieve both gelatinization and enzymatic hydrolysis of starch, but this process can result in incomplete gelatinization of some starch granules and insufficient enzymatic hydrolysis, leading to low starch utilization. The hydrothermal gelatinization process, on the other hand, involves enzymatic hydrolysis of fully gelatinized starch to achieve starch liquefaction. This method has the following limitations: First, the existing starch emulsion system has a low solids content (5%-10%, w / w), meaning low starch concentration, poor production capacity, and significant energy consumption for product concentration. Second, increasing the starch concentration significantly increases the system viscosity, hindering the effective diffusion and liquefaction of saccharifying enzymes, affecting the enzymatic reaction rate and product yield, and greatly increasing the difficulty of subsequent dextrin separation.

[0004] Maltodextrin products with similar DE values ​​exhibit significant differences in molecular weight distribution due to differences in production processes and raw material sources, resulting in completely different properties. Therefore, the DE value is insufficient to reflect the true processing quality of a product, and further differentiation of maltodextrin products at the molecular level is necessary (Chronakis I S. On the molecular characteristics, compositional properties, and structural-functional mechanisms of maltodextrins: A review. DOI: 10.1080 / 10408699891274327). High-molecular-weight maltodextrin products (DP>50±5) have physiological functions such as regulating the intestines and delaying postprandial blood sugar levels, and can be used as functional ingredients in special dietary supplements. Lower-molecular-weight maltodextrins (DP 30±5-50±5) have low hygroscopicity and a suitable chain length distribution, which is beneficial for the encapsulation of flavor components and active substances. Low-molecular-weight maltodextrins (DP 10±5-30±5) have good transparency and solubility, and are relatively stable as food additives. However, low-molecular-weight maltodextrins contain high levels of reducing sugars such as glucose and maltose, which are prone to hygroscopicity and browning reactions, affecting product quality. Therefore, it is important to fractionate maltodextrin to obtain maltodextrin components with a uniform degree of polymerization distribution.

[0005] Currently, maltodextrin separation and purification methods mainly include chromatography, membrane filtration, and phase transition separation. Chromatography relies primarily on the properties of the filler, resulting in high costs and low throughput. Phase transition separation, based on the dependence of the solubility of different molecular weight fractions in the same polymer on the properties of the solvent, achieves precipitation and fractionation of the substance. However, this single fractionation method suffers from problems such as poor grading results and high solvent consumption. For example, patent CN113699198A enzymatically hydrolyzes and liquefies a starch slurry with a mass concentration of 10% to 20%, adds activated carbon for adsorption, and then filters, concentrates, and dries to obtain maltodextrin with a DE value of 1 to 2. Patent CN104789616B uses ethanol, polyethylene glycol, and salt ions to separate single-component dextrin, and by gradually increasing the ethanol concentration, separates dextrin components of different molecular weights. Patent CN111304270A prepares non-reducing low-polymerization maltodextrin with uniform polymerization degree by adding cyclodextrin glucosyltransferase (CGTase), cyclodextrin degrading enzyme (CDase), and / or maltooligosaccharide trehalose synthase (MTSase). It can be seen that the existing maltodextrin preparation methods all have problems such as low starch solids content and inefficient separation of uniform maltodextrin.

[0006] In addition, patent CN104198668B uses polyethylene glycol to gradually precipitate dextrin components with molecular weights ranging from large to small, and obtains dextrin components with molecular weights ranging from 5.443×10 3 ~3.297×10 4 Da dextrin; although the components obtained by dextrin separation are uniform through this method, the separation steps are cumbersome and time-consuming. After each addition of polyethylene glycol, it is necessary to stand for 24 hours. The amount of polyethylene glycol used is large, and the concentration of dextrin used for separation is only 3.6%, which is not suitable for the separation of dextrin with high solid content. At the same time, the production intensity of this method is low, which is not conducive to industrial production. Patent CN107574198B is a method for separating spiral dextrin by alcohol. Specifically, it uses 10% starch milk as raw material and uses ethanol solutions of different volume fractions to separate cyclodextrin. The use of ethanol separation requires standing at 4°C for 12 hours, and the prepared DP value is as low as 40. Moreover, the concentration of dextrin separated by this method is low, and it is also not suitable for the separation of dextrin with high solid content. The separation effect is general, and the degree of polymerization of dextrin is large.

[0007] Therefore, there is an urgent need to develop a preparation method for maltodextrin that has high starch solids content, high production intensity, high raw material utilization rate and a certain uniformity and is more suitable for industrial production. Summary of the Invention

[0008] In view of the problems of low starch solids content, high viscosity, insufficient enzymatic hydrolysis, large separation solvent consumption, and low production capacity in maltodextrin prepared by traditional hydrothermal gelatinization and jet liquefaction, the present invention provides a method for preparing maltodextrin. Specifically, high-temperature dry-heat amorphization, enzymatic hydrolysis liquefaction, polyethylene glycol precipitation classification combined with alcohol complexation classification and membrane interception classification technology are adopted. After batch drying, large-scale and efficient preparation of maltodextrin products with high yield and uniform polymerization degree distribution is achieved on the basis of processing high-solids starch milk.

[0009] A first object of the present invention is to provide a method for preparing a maltodextrin product, comprising the steps of:

[0010] (1) Dry heat amorphization: dry heat treat the starch at 180-200°C for 8-10 min to obtain dry heat treated starch;

[0011] (2) Enzymatic hydrolysis and liquefaction: The starch after dry heat treatment is mixed with water to form starch milk, wherein the starch accounts for 35% to 40% of the total mass of the starch milk; the starch milk is then enzymatically hydrolyzed and inactivated to obtain an enzymatic hydrolyzate;

[0012] (3) Decolorization and impurity removal: decolorizing and removing impurities from the enzymatic hydrolyzate obtained in step (2) to obtain a decolorized and impurity-removed solution;

[0013] (4) Classification: First, the decolorized and impurity-removed solution obtained in step (3) is mixed with polyethylene glycol 6000, and centrifuged to obtain a fraction 1 and a supernatant 1; wherein the amount of polyethylene glycol 6000 added is 30-40 g / 100 mL of the decolorized and impurity-removed solution;

[0014] The supernatant 1 is then mixed with anhydrous ethanol to obtain a mixed solution, and the mixed solution is centrifuged to obtain fractionated fraction 2 and supernatant 2; wherein the volume fraction of anhydrous ethanol in the mixed solution is 50% to 60%;

[0015] Finally, the supernatant 2 was separated using a 1000-2000 Da hollow fiber membrane to obtain fraction 3;

[0016] (5) Drying: collecting the fraction 1, fraction 2, and fraction 3 obtained in step (4), and drying them separately to obtain a maltodextrin product.

[0017] In one embodiment, the starch described in step (1) is one or more of cereal starch, algae starch, and tuber starch; optionally, the starch includes ordinary corn starch, wheat starch, chlorella starch, tapioca starch, potato starch, etc.

[0018] In one embodiment, the dry heat amorphization in step (1) is specifically as follows:

[0019] The starch was spread on a steel plate with a thickness of 2-3 mm, and then dry-heat treated at 180-200°C for 8-10 min. Alternatively, the starch was spread on a steel plate with a thickness of 2-3 mm, and then dry-heat treated at 200°C for 8 min.

[0020] In one embodiment, the modulation in step (2) is carried out at a pH of 5.0-6.0 and a temperature of 65-70° C. for 4-6 minutes. Alternatively, the modulation in step (2) is carried out at a pH of 5.0 and a temperature of 70° C. for 5 minutes.

[0021] In one embodiment, the enzymatic hydrolysis in step (2) is performed by adding 10 to 20 U / g α-amylase at a pH of 5.0 to 6.0 and 65 to 70°C for 5 to 10 minutes. Alternatively, the enzymatic hydrolysis in step (2) is performed by adding 10 U / g α-amylase at a pH of 5.0 and 65°C for 5 minutes.

[0022] In one embodiment, the decolorization and impurity removal in step (3) are performed using activated carbon and ion exchange resin; wherein, the activated carbon is used for decolorization by keeping the temperature at 80-90°C for 15-30 minutes, and the amount of activated carbon added is 1 g / 100 mL of enzymatic hydrolysate (abbreviated as 1%, w / v).

[0023] In one embodiment, the centrifugation in step (4) is performed at 8000-9000 r / min for 8-10 min.

[0024] In one embodiment, the molecular weight cut-off of the hollow fiber membrane in step (4) is 1000 or 2000 Da.

[0025] In one embodiment, the drying in step (5) includes but is not limited to: heat pump drying, vacuum drying, microwave drying, freeze drying, and hot air drying; optionally, the drying is hot air drying, and the drying temperature is 50-70°C.

[0026] The second object of the present invention is to provide a maltodextrin product prepared by the above method.

[0027] In one embodiment, the degree of polymerization of the maltodextrin product includes: DP>50±5 or DP is between 30±5 and 50±5 or DP is between 10±5 and 30±5.

[0028] The third object of the present invention is to provide the use of the above-mentioned maltodextrin product in the preparation of special dietary functional ingredients, flavor substances or active molecule embedding carriers, and food additives.

[0029] In one embodiment, the application is to use the maltodextrin product with DP>50±5 as a special dietary functional ingredient.

[0030] In one embodiment, the application is to use a maltodextrin product with a DP of 30±5 to 50±5 as a flavor substance or active molecule embedding carrier.

[0031] In one embodiment, the application is to use the maltodextrin product with a DP of 10±5 to 30±5 as a food additive.

[0032] Beneficial effects of the present invention:

[0033] Unlike traditional methods for preparing maltodextrin, this method utilizes dry-heat amorphization technology to process starch. High-solids starch milk (35%-40%, w / w) is enzymatically hydrolyzed, followed by decolorization with activated carbon. Separation is achieved using polyethylene glycol precipitation fractionation combined with alcohol complexation and membrane interception fractionation. After separation, maltodextrin products with varying DP ranges are obtained through batch drying. While processing high-solids starch milk, this method ensures high-yield, uniform DP distribution for large-scale, efficient production, achieving a maltodextrin yield exceeding 81%. Three DP ranges of maltodextrin fractions are obtained, each corresponding to a specific application.

[0034] Specifically:

[0035] (1) The present invention uses dry heat amorphization to treat starch, which reduces the viscosity of starch during gelatinization, promotes starch declustering and gelatinization, and increases the solid content of starch milk, with the solid content reaching 35% to 40% (w / w). The method of the present invention increases the production capacity of maltodextrin and is suitable for large-scale production.

[0036] (2) The present invention sequentially uses polyethylene glycol precipitation fractionation, ethanol complex fractionation, and membrane interception fractionation techniques to separate maltodextrin from starch milk with a high solid content. While narrowing the distribution range of the degree of polymerization of maltodextrin, a maltodextrin product with a uniform degree of polymerization is obtained. The present invention also improves the utilization rate of starch, reaching a maximum of 82.6%;

[0037] (3) The present invention can be directly dried in batches after interception and classification, saving energy consumption required for the concentration process and saving drying costs. It has significant environmental advantages and is more suitable for industrial production.

[0038] (4) The polymerization degrees of the maltodextrin products prepared by the present invention are: component 1 DP>50±5, component 2 DP 30±5~50±5, component 3 DP 10±5~30±5; component 1 can be used as a functional ingredient for special meals; component 2 can be used as an embedding carrier for flavor substances and active molecules; component 3 can be used as a food additive, and has great application potential. DETAILED DESCRIPTION

[0039] The following describes preferred embodiments of the present invention. It should be understood that the embodiments are for better explanation of the present invention and are not intended to limit the present invention.

[0040] Materials and equipment:

[0041] The high-temperature dry-heat amorphization equipment used in the following experiments was a GZX-9146MBE blast drying oven produced by Shanghai Boxun Company; α-amylase was purchased from Sigma Company with an enzyme activity of 50,000 U / mL.

[0042] Test method:

[0043] 1. Determination of starch hydrolysis rate (DE)

[0044] Reducing sugars were measured according to the Lane-Eynon method and the results were used to calculate the DE content. Specifically:

[0045] Dissolve 0.50 g (dry basis) of anhydrous glucose reference and maltodextrin product in distilled water to 250 mL, then shake well to prepare the glucose reference and sample solutions. Measure 25 mL of Fehling's reagent and 10 mL of distilled water, shake well, and heat to boiling. Add two drops of 1% methylene blue solution. Titrate with the glucose reference or sample solution until the blue color disappears. Record the volume of glucose reference or sample solution required. The DE value is the percentage of reducing sugars (calculated as glucose) in the dry matter of the syrup and is calculated as follows:

[0046]

[0047] 2. Determination of starch utilization

[0048] Starch utilization is the maltodextrin yield, which is expressed as the ratio of the total mass of maltodextrin obtained after drying to the mass of starch used.

[0049] 3. Determination of chain length distribution of maltodextrin

[0050] The chain length distribution of maltodextrin was determined by HPAEC-PAD. The pulsed amperometric detector was an ICS-5000+, the column was a Dionex CarboPAC PA200, the mobile phase was a 150 mmol / L NaOH solution, the flow rate was 0.4 mL / min, and the injection volume was 25 μL.

[0051] Example 1: Preparation and separation of maltodextrin

[0052] Corn starch was first subjected to a 200℃ dry-heat amorphization treatment to prepare a 35% (w / w) starch milk, which was then enzymatically hydrolyzed at 70℃ and decolorized with activated carbon. Maltodextrin products with different degrees of polymerization were obtained by drying, followed by fractionation using 40% (w / v) polyethylene glycol 6000 precipitation, 60% (v / v) ethanol complexation, and membrane interception.

[0053] The specific experimental steps are as follows:

[0054] (1) Dry heat amorphization: spread corn starch on a steel plate with a thickness of 3 mm and dry heat treat it at 200 °C for 8 min to obtain dry heat treated starch;

[0055] (2) Enzymatic hydrolysis and liquefaction: Add water to the starch after dry heat treatment, adjust the pH to 5.0, and keep it at 70℃ for 5 min to prepare a 35% (w / w, starch dry basis accounts for the total mass of starch milk) starch milk; then add 10 U / g α-amylase to the starch milk and enzymatically hydrolyze it at pH 5.0 and 70℃ for 5 min; adjust the pH of the solution to 4.5 to inactivate the enzyme and obtain an enzymatic hydrolyzate;

[0056] (3) Decolorization and impurity removal: 1% (w / v, g / mL) activated carbon was added to the enzymatic hydrolyzate and decolorized at 80°C for 30 min. The metal salts and pigments were then removed by ion exchange resin to obtain a decolorized and impurity-removed solution.

[0057] (4) Classification: The decolorized and impurity-removed solution is sequentially subjected to polyethylene glycol precipitation classification, ethanol complexation classification, and membrane interception classification to obtain maltodextrin components with uniform polymerization degree distribution:

[0058] Polyethylene glycol precipitation fractionation: The decolorized and impurity-removed solution was mixed with polyethylene glycol 6000, stirred thoroughly, and allowed to stand for 2 h. The mixture was then centrifuged at 8000 rpm for 10 min to obtain fraction 1 and supernatant 1. The amount of polyethylene glycol 6000 added was 40% (w / v, g / mL).

[0059] Ethanol complex fractionation: Supernatant 1 was mixed with anhydrous ethanol to obtain a mixed solution, so that the volume fraction of anhydrous ethanol in the mixed solution reached 60%, and the mixture was allowed to stand for 30 minutes, and centrifuged at 8000 rpm for 10 minutes to obtain fraction 2 and supernatant 2;

[0060] Membrane fractionation: Supernatant 2 was separated using a 2000 Da hollow fiber membrane to obtain fraction 3;

[0061] (5) Drying: The graded component 1, graded component 2, and graded component 3 were dried with hot air at 70°C to obtain three groups of maltodextrin products with uniform polymerization degree.

[0062] Example 2: Preparation and separation of maltodextrin

[0063] Corn starch was first subjected to a 180°C dry-heat amorphization treatment to prepare a 35% (w / w) starch milk, which was then enzymatically hydrolyzed at 65°C and decolorized with activated carbon. Maltodextrin products with different degrees of polymerization were obtained by drying, followed by fractionation using 30% (w / v) polyethylene glycol 6000 precipitation, 50% (v / v) ethanol complexation, and membrane interception.

[0064] The specific experimental steps are as follows:

[0065] (1) Dry heat amorphization: spread corn starch on a steel plate with a thickness of 2 mm and dry heat treat it at 180°C for 10 min to obtain dry heat treated starch;

[0066] (2) Enzymatic hydrolysis and liquefaction: Add water to the starch after dry heat treatment, adjust the pH to 6.0, and keep it at 65℃ for 5 min to prepare a 35% (w / w, starch dry basis accounts for the total mass of starch milk) starch milk; then add 20 U / g α-amylase to the starch milk and enzymatically hydrolyze it at pH 5.0 and 65℃ for 10 min; adjust the pH of the solution to 4.5 to inactivate the enzyme and obtain the enzymatic hydrolyzate;

[0067] (3) Decolorization and impurity removal: 1% (w / v, g / mL) activated carbon was added to the enzymatic hydrolyzate and decolorized at 90°C for 30 min. The metal salts and pigments were then removed by ion exchange resin to obtain a decolorized and impurity-removed solution.

[0068] (4) Classification: The decolorized and impurity-removed solution is sequentially subjected to polyethylene glycol precipitation classification, ethanol complexation classification, and membrane interception classification to obtain maltodextrin components with uniform polymerization degree distribution:

[0069] Polyethylene glycol precipitation fractionation: The decolorized and impurity-removed solution was mixed with polyethylene glycol 6000, stirred thoroughly, and allowed to stand for 2 h. Centrifuged at 8000 rpm for 10 min to obtain fraction 1 and supernatant 1. The amount of polyethylene glycol 6000 added was 30% (w / v, g / mL).

[0070] Ethanol complex fractionation: Supernatant 1 was mixed with anhydrous ethanol to obtain a mixed solution, so that the volume fraction of anhydrous ethanol in the mixed solution reached 50%, and the mixture was allowed to stand for 30 minutes, and centrifuged at 8000 rpm for 10 minutes to obtain fraction 2 and supernatant 2;

[0071] Membrane fractionation: Supernatant 2 was separated using a 2000 Da hollow fiber membrane to obtain fraction 3;

[0072] (5) Drying: The graded component 1, graded component 2, and graded component 3 were dried with hot air at 70°C to obtain three groups of maltodextrin products with uniform polymerization degree.

[0073] Example 3: Preparation and separation of maltodextrin

[0074] Cassava starch was first subjected to a 180°C dry-heat amorphization treatment to prepare a 40% (w / w) starch milk, which was then enzymatically hydrolyzed at 70°C and decolorized with activated carbon. Maltodextrin products with different degrees of polymerization were obtained by drying, followed by fractionation using 30% (w / v) polyethylene glycol precipitation, 60% (v / v) ethanol complexation, and membrane interception.

[0075] The specific experimental steps are as follows:

[0076] (1) Dry heat amorphization: Cassava starch was spread on a steel plate with a thickness of 3 mm and dry-heated at 180 °C for 10 min to obtain dry heat-treated starch;

[0077] (2) Enzymatic hydrolysis and liquefaction: Add water to the starch after dry heat treatment, adjust the pH to 5.0, and keep it at 70℃ for 5 min to prepare a 40% (w / w, starch dry basis accounts for the total mass of starch milk) starch milk; then add 20 U / g α-amylase to the starch milk and enzymatically hydrolyze it at pH 5.0 and 70℃ for 10 min; adjust the pH of the solution to 4.5 to inactivate the enzyme and obtain the enzymatic hydrolyzate;

[0078] (3) Decolorization and impurity removal: 1% (w / v, g / mL) activated carbon was added to the enzymatic hydrolyzate and decolorized at 80°C for 30 min. The metal salts and pigments were then removed by ion exchange resin to obtain a decolorized and impurity-removed solution.

[0079] (4) Classification: The decolorized and impurity-removed solution is sequentially subjected to polyethylene glycol precipitation classification, ethanol complexation classification, and membrane interception classification to obtain maltodextrin components with uniform polymerization degree distribution:

[0080] Polyethylene glycol precipitation fractionation: The decolorized and impurity-removed solution was mixed with polyethylene glycol 6000, stirred thoroughly, and allowed to stand for 2 h. Centrifuged at 8000 rpm for 10 min to obtain fraction 1 and supernatant 1. The amount of polyethylene glycol 6000 added was 30% (w / v, g / mL).

[0081] Ethanol complex fractionation: Supernatant 1 was mixed with anhydrous ethanol to obtain a mixed solution, so that the volume fraction of anhydrous ethanol in the mixed solution reached 60%, and the mixture was allowed to stand for 30 minutes, and centrifuged at 8000 rpm for 10 minutes to obtain fraction 2 and supernatant 2;

[0082] Membrane fractionation: Supernatant 2 was separated using a 1000 Da hollow fiber membrane to obtain fraction 3;

[0083] (5) Drying: The graded component 1, graded component 2, and graded component 3 were dried with hot air at 70°C to obtain three groups of maltodextrin products with uniform polymerization degree.

[0084] Comparative Example 1: Preparation of maltodextrin by hydrothermal gelatinization

[0085] On the basis of Example 1, step (1) and step (2) were changed as follows: 35% (w / w, dry starch basis accounts for the total mass of starch milk) starch milk was prepared and gelatinized in a boiling water bath for 30 min. Other conditions were the same as those in Example 1.

[0086] Comparative Example 2: Changing the dry heat amorphization temperature to 140°C

[0087] On the basis of Example 1, the dry heat amorphization temperature in step (1) was changed to 140° C., and the other conditions were the same as those in Example 1.

[0088] Comparative Example 3: Preparation of maltodextrin by jet liquefaction

[0089] On the basis of Example 1, the dry heat amorphization operation of step (1) was omitted, and step (2) was changed to gelatinizing the starch by jet liquefaction, that is, 10 U / g α-amylase was added to the starch milk and a liquefied liquid was obtained by jet liquefaction. The pressure of the jet liquefaction material was set to 0.35 MPa, the steam pressure was 0.1 MPa, the temperature was 90°C, the time was 8 min, and then the temperature was kept at 70°C for 5 min. Other conditions were the same as in Example 1.

[0090] Comparative Example 4: Preparation of maltodextrin without classification

[0091] Based on Example 1, step (4) classification was omitted, and other conditions were the same as in Example 1. The prepared maltodextrin was detected, and its DP distribution was 1-70, and the molecular weight distribution was uneven, and it was a mixture of glucose, maltose, oligosaccharides and polysaccharides.

[0092] Comparative Example 5: Preparation of maltodextrin using polyethylene glycol precipitation and classification alone

[0093] Based on Example 1, the classification step in step (4) is changed to:

[0094] The decolorized and impurity-removed solution was mixed with polyethylene glycol 6000 at a concentration of 40% (w / v, g / mL), stirred thoroughly, allowed to stand for 2 h, and centrifuged at 8000 rpm for 10 min to obtain fraction 1 and supernatant 1.

[0095] Polyethylene glycol 6000 was further added to supernatant 1 until the amount of polyethylene glycol 6000 added reached 50% (w / v, g / mL). After thorough stirring, the mixture was allowed to stand for 2 h and centrifuged at 8000 r / min for 10 min to obtain fraction 2. Other conditions were the same as those in Example 1.

[0096] Comparative Example 6: Preparation of maltodextrin using only alcohol complexation and fractionation technology

[0097] Based on Example 1, the classification step in step (4) is changed to:

[0098] The decolorized and impurity-removed solution was mixed with anhydrous ethanol to obtain a mixed solution, wherein the volume fraction of anhydrous ethanol in the mixed solution reached 30%, the solution was allowed to stand for 30 minutes, and centrifuged at 8000 rpm for 10 minutes. The resulting precipitate was maltodextrin fraction 1 and supernatant 1.

[0099] Anhydrous ethanol was further added to the supernatant 1 to make the volume fraction of anhydrous ethanol reach 60%, and the mixture was allowed to stand for 30 minutes and centrifuged at 8000 r / min for 10 minutes. The resulting precipitates were maltodextrin fraction 2 and supernatant 2.

[0100] Anhydrous ethanol was further added to the supernatant 2 to make the volume fraction of anhydrous ethanol reach 80%, and the mixture was allowed to stand for 30 min and centrifuged at 8000 r / min for 10 min. The resulting precipitate was the maltodextrin fraction 3. Other conditions were the same as those in Example 1.

[0101] Comparative Example 7: Preparation of maltodextrin using only membrane interception and classification technology

[0102] Based on Example 1, the classification step in step (4) is changed to:

[0103] Hollow fiber membranes with molecular weight cut-offs of 10,000, 5,000, and 2,000 Da were used to separate the decolorized and impurity-removed solutions, respectively, to obtain maltodextrin fractions 1, 2, and 3, respectively. Other conditions were the same as in Example 1.

[0104] Comparative Example 8: Preparation of maltodextrin, changing the order of fractionation

[0105] Based on Example 1, the order of the grading steps in step (4) is changed to:

[0106] Ethanol complexation fractionation: The decolorized and impurity-removed solution was mixed with anhydrous ethanol to make the volume fraction of anhydrous ethanol reach 60%, allowed to stand for 30 minutes, and centrifuged at 8000 rpm for 10 minutes. The resulting precipitate was maltodextrin fraction 1 and supernatant 1.

[0107] Polyethylene glycol precipitation fractionation: Supernatant 1 was mixed with polyethylene glycol 6000 at a concentration of 40% (w / v, g / mL). After thorough stirring, the mixture was allowed to stand for 2 h and centrifuged at 8000 rpm for 10 min. The resulting precipitate was maltodextrin fraction 2 and supernatant 2.

[0108] Membrane fractionation: The membrane separation was carried out by using a hollow fiber membrane with a molecular weight cut-off of 2000 Da to separate the supernatant obtained by ethanol complexation fractionation to obtain maltodextrin fraction 3. Other conditions were the same as those in Example 1.

[0109] The polymerization degree and yield of the maltodextrin products prepared in Examples 1 to 3 and Comparative Examples 1 to 8 were tested, and the results are shown in Tables 1 and 2.

[0110] Table 1 Maltodextrin chain length distribution

[0111]

[0112] Note: DP stands for degree of polymerization; “-” represents the absence of this fraction; the content of the final separated product represents the percentage of maltodextrin in the three fractions to the total maltodextrin weight, and the sum of the three components is 100%.

[0113] Table 2 Maltodextrin yield

[0114]

[0115] As can be seen from Tables 1 and 2, the maltodextrin yield (starch utilization rate) of the method in Example 1 can reach 82.1%, and the chain lengths of the maltodextrin fractions 1, 2, and 3 are distributed in the range of DP>50, DP 30-50, and DP 10-30, respectively; the maltodextrin yield of the method in Example 2 can reach 81.7%, and the chain lengths of the maltodextrin fractions 1, 2, and 3 are distributed in the range of DP>55, DP 35-55, and DP 10-35, respectively; the maltodextrin yield of the method in Example 3 can reach 82.6%, and the chain lengths of the maltodextrin fractions 1, 2, and 3 are distributed in the range of DP>55, DP 25-55, and DP 5-25, respectively.

[0116] Comparing Example 1 with Comparative Example 4, it can be seen that the maltodextrin products after fractionation have a uniform degree of polymerization. The fractionated maltodextrin products fall into three groups: DP > 50, DP 30-50, and DP 10-30. In contrast, Comparative Example 4, which is unfractionated maltodextrin, has a DP range of 1-70. The resulting maltodextrin is a mixture of glucose, maltose, oligosaccharides, and polysaccharides, exhibiting poor uniformity. Glucose and maltose have high reducing properties, and when present with amino acids or proteins, they are prone to Maillard reactions, thereby reducing the quality of the maltodextrin product.

[0117] In addition, the three groups of maltodextrin components obtained after fractionation and separation in Example 1 have improved polymerization degree uniformity, and the product can be quickly dried by hot air drying technology. Compared with the concentration and spray drying technology required for unfractionated maltodextrin, it saves drying costs and is beneficial to improving the stability of maltodextrin in industrial preparation.

[0118] By comparing Examples 1 to 3 with Comparative Examples 1 to 3, it can be seen that the use of dry heat amorphization to treat starch can increase the maltodextrin yield to more than 80%. By comparing Example 1 with Comparative Example 2, it can be seen that the temperature of dry heat amorphization is a key factor affecting the maltodextrin yield, and the maltodextrin yield prepared by dry heat treating starch at a lower temperature is lower.

[0119] It can be seen that the viscosity of starch milk is high under hydrothermal gelatinization conditions, which hinders the diffusion and contact of enzyme and substrate during the subsequent enzymatic hydrolysis reaction, reduces the reaction rate and causes incomplete enzymatic hydrolysis, resulting in a low yield of maltodextrin; lowering the dry heat amorphization temperature will reduce the degree of starch chain declustering, increase the viscosity of starch paste, weaken the fluidity, lead to incomplete enzymatic hydrolysis, and further increase the loss of classification; during the jet liquefaction process, starch gelatinization and enzymatic hydrolysis start at the same time, and starch gelatinization is not complete, resulting in a decrease in maltodextrin yield. Jet liquefaction also increases the energy consumption and economic cost of maltodextrin production.

[0120] By comparing Example 1 with Comparative Examples 6 and 7, it can be seen that the yield of maltodextrin using polyethylene glycol precipitation fractionation, ethanol complexation fractionation, and membrane interception fractionation in sequence is higher than that using only one of the separation methods; by comparing Example 1 with Comparative Examples 5 and 8, it can be seen that only under a specific order of fractionation steps, the separation effect of maltodextrin components with different DP values ​​is good and a high yield is maintained.

[0121] Comparative Example 5 only yielded two maltodextrin fractions: one with a DP > 50 and one with a DP of 1-50. While the maltodextrin yield was high, the separation was poor. The maltodextrin fraction with a DP of 1-50 was not only ineffective for encapsulating flavor components and active ingredients, but also lacked transparency and solubility. Furthermore, due to the presence of small-molecule reducing sugars, it was susceptible to hygroscopicity and browning. The poor separation in Comparative Example 5 was attributed to the following: when polyethylene glycol 6000 was added at a level of 40% (w / v, g / mL) for fractionation, the maltodextrin fraction with a DP > 50 precipitated, leaving the remaining maltodextrin fraction with a DP < 50 in the supernatant. Further addition of polyethylene glycol resulted in excessive viscosity in the reaction system, making it impossible to narrow the DP distribution of the product by centrifugation.

[0122] The yield of maltodextrin prepared in Comparative Example 6 was 65.5%. This was because the volume of the maltodextrin solution increased significantly and the concentration decreased during the addition of anhydrous ethanol, resulting in increased separation loss.

[0123] The maltodextrin yield obtained in Comparative Example 7 was reduced to 58.4%. This is because the high substrate concentration of maltodextrin solution is difficult to intercept during membrane separation, resulting in a reduced maltodextrin yield. Furthermore, the large amount of hollow fiber membrane used in the separation process increased maltodextrin loss and the cost of the hollow fiber membrane.

[0124] Comparative Example 8 yielded only two maltodextrin fractions with chain lengths ranging from DP > 30 and DP 10-30. Adjusting the order of the fractionation steps resulted in an inability to narrow the distribution range of the degree of polymerization for maltodextrins with DP > 30, while the maltodextrin fractions with DP > 50 and DP 30-50 could not be separated. This is because polyethylene glycol has difficulty precipitating maltodextrin fractions with smaller molecular weights. Using ethanol complexation as the first step causes the smaller DP fractions to precipitate together with the larger DP fractions, resulting in a maltodextrin fraction with DP > 30. In this case, using polyethylene glycol to precipitate the maltodextrin fraction with DP < 30 in supernatant 1 resulted in no significant separation. Of the fractions separated in this order, only the maltodextrin fraction with DP 10-30 can be used for encapsulation of flavor components and active substances. Since the fraction with DP > 30 cannot be separated into fractions with DP > 50 and DP 30-50, its use as a functional ingredient in specialty foods is poor, and its encapsulation efficiency for flavor components, active substances, etc. is low.

[0125] In summary, polyethylene glycol has a good fractionation effect on macromolecular maltodextrins, effectively precipitating maltodextrin fractions with a DP > 50. Ethanol complexation effectively separates maltodextrin fractions with a DP > 30, but is unable to separate maltodextrin fractions with a DP < 15. To save solvent consumption and drying costs, membrane separation is used to filter maltodextrin fractions with a DP < 10. The combined use of these three methods yields three groups of maltodextrin fractions with chain lengths ranging from DP > 50 ± 5, DP 30 ± 5 to 50 ± 5, and DP 10 ± 5 to 30 ± 5, each with a specific range of application.

[0126] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for preparing maltodextrin, characterized in that: The steps include: (1) Dry heat amorphization: dry heat treatment of starch at 180-200°C for 8-10 min to obtain dry heat treated starch; (2) Enzymatic liquefaction: The starch after dry heat treatment is mixed with water to form starch milk, wherein the starch accounts for 35% to 40% of the total mass of the starch milk; the starch milk is then enzymatically hydrolyzed and inactivated to obtain an enzymatic hydrolyzate; (3) Decolorization and impurity removal: decolorizing and impurity removal the enzymatic hydrolyzate obtained in step (2) to obtain a decolorized and impurity-free solution; (4) Classification: first, the decolorized and impurity-free solution obtained in step (3) is mixed with polyethylene glycol 6000, and centrifuged to obtain a classification component 1 and a supernatant 1; wherein the amount of polyethylene glycol 6000 added is 30-40 g / 100 mL of the decolorized and impurity-free solution; Then, the supernatant 1 is mixed with anhydrous ethanol to obtain a mixed solution, and the mixed solution is centrifuged to obtain a fractionated component 2 and a supernatant 2; wherein the volume fraction of the anhydrous ethanol in the mixed solution is 50% to 60%; Finally, the supernatant 2 was separated using a 1000-2000 Da hollow fiber membrane to obtain fractionated components 3; (5) Drying: collecting the fraction 1, fraction 2 and fraction 3 obtained in step (4), and drying them separately to obtain maltodextrin products.

2. The method according to claim 1, characterized in that The starch in step (1) includes but is not limited to cereal starch, algae starch, and potato starch.

3. The method according to claim 1, characterized in that The preparation in step (2) is carried out at a pH of 5.0-6.0 and a temperature of 65-70°C for 4-6 minutes.

4. The method according to claim 1, characterized in that In step (2), the enzymatic hydrolysis is performed by adding 10-20 U / g α-amylase and performing enzymatic hydrolysis at a pH of 5.0-6.0 and 65-70° C. for 5-10 min.

5. The method according to claim 1, characterized in that In step (3), activated carbon and ion exchange resin are used for decolorization and impurity removal; wherein, the activated carbon is used for decolorization by keeping the temperature at 80-90°C for 15-30 min, and the amount of activated carbon added is 1 g / 100 mL of enzymatic hydrolyzate.

6. The method according to any one of claims 1 to 5 for preparing a maltodextrin product.

7. The maltodextrin product according to claim 6, characterized in that The degree of polymerization of maltodextrin products includes: DP>50±5 or DP is between 30±5~50±5 or DP is between 10±5~30±5.

8. Use of the maltodextrin product according to claim 6 or 7 in the preparation of special dietary functional ingredients, flavor substances or active molecule embedding carriers, and food additives.

9. The use according to claim 8, characterized in that The application is to use maltodextrin products with DP>50±5 as special dietary functional ingredients; to use maltodextrin products with DP between 30±5 and 50±5 as flavor substances or active molecule embedding carriers; and to use maltodextrin products with DP between 10±5 and 30±5 as food additives.

Images