A kind of preparation method of maltodextrin

Abstract

The present invention discloses a method for preparing maltodextrin, and belongs to the technical field of development of special dietary carbohydrate ingredients. The present invention uses starch as raw material, and utilizes dry heat amorphization technology to decluster the starch molecular chains while increasing the solid content of the reaction system and reducing the viscosity of the system; then, the molecular weight distribution range of maltodextrin is narrowed by polyethylene glycol precipitation classification, alcohol complexation classification combined with membrane interception classification technology; finally, a maltodextrin product with uniform distribution of polymerization degree is obtained by hot air drying, and the yield of maltodextrin can reach more than 80%. The functional properties of the different maltodextrin graded components collected by the present invention are stable, and they have great application prospects in the fields of food additives, flavor substance embedding carriers, and special dietary functional ingredients. At the same time, the technical solution of the present invention improves the production efficiency of maltodextrin, saves drying costs and energy consumption, and has significant environmental advantages.

Description

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 hydrolyzate with a degree of hydrolysis (DE) less than 20 obtained by acid or enzyme treatment using starch as raw material. Its main components are dextrin with a degree of polymerization of more than 10 and a small amount of oligosaccharides with a degree of polymerization of less than 10. It has the characteristics of wide molecular weight distribution and large polydispersity coefficient. At present, maltodextrin is usually produced by the process of jet liquefaction and hydrothermal gelatinization. Jet liquefaction can achieve gelatinization and enzymatic hydrolysis of starch at the same time, but some starch granules are not completely gelatinized in the process, which makes it difficult to react with enzymes, resulting in low starch utilization rate; while the hydrothermal gelatinization process is to perform enzymatic hydrolysis on completely gelatinized starch to achieve starch liquefaction. The limitation of this method is that the solid content of the existing starch milk system is low (5% to 10%), that is, the starch concentration is low, resulting in poor production capacity and serious energy consumption for product concentration; second, if the starch concentration is increased, the viscosity of the system will increase significantly, which will not only hinder the effective diffusion and liquefaction of the enzyme, but also affect the enzymatic reaction rate and product yield, and also greatly increase the difficulty of subsequent dextrin separation.

[0003] Maltodextrin products with similar DE values ​​show great differences in molecular weight distribution due to different production processes and raw material sources, and thus may have completely different properties. Therefore, the DE value is not enough to reflect the true processing quality of the product, and it is necessary to further distinguish maltodextrin products at the molecular level (Chronakis I S. On the molecular characteristics, compositional properties, and structural-functional mechanisms of maltodextrins: A review [J]. Critical Reviews in Food Science and Nutrition, 1998, 38 (7): 599-637). High molecular weight maltodextrin products (DP>50±5) have physiological functions such as regulating the intestines and delaying postprandial blood sugar, and can be used as functional food ingredients; low molecular weight maltodextrin (DP 30±5~50±5) has low hygroscopicity, and the appropriate chain length distribution is beneficial for its use in the embedding of flavor components, active substances, etc.; low molecular weight maltodextrin (DP 10±5~30±5) has good transparency and solubility, and has good stability as a food additive; while small molecular weight maltodextrin has a high content of reducing sugars such as glucose and maltose, which is easy to absorb moisture and browning reaction, affecting product quality. It can be seen that it is of great significance to grade and separate maltodextrin to obtain components with uniform distribution of polymerization degree.

[0004] At present, the separation and purification methods of maltodextrin mainly include chromatographic separation, membrane filtration separation and phase transition separation. Among them, the chromatographic separation method mainly depends on the properties of the filler, with high cost and small processing volume. The phase transition separation method is based on the dependence of the solubility of different molecular weight fractions of the same polymer on the properties of the solvent to achieve the precipitation classification of the substance. Its single classification method has problems such as poor classification effect and large solvent consumption. A novel preparation method of maltodextrin in the prior art (CN113699198A) is enzymatically hydrolyzing and liquefying a starch slurry with a mass concentration of 10% to 20%, adding activated carbon for adsorption, filtering, concentrating and drying to obtain maltodextrin with a DE value of 1 to 2; a method for producing single-degree of polymerization maltodextrin by multi-enzyme coupling in the prior art (CN111304270A) discloses the addition of cyclodextrin glucosyltransferase (CGTase), cyclodextrin degrading enzyme (CDase) and / or maltooligosaccharide trehalose synthase (MTSase) to prepare non-reducing low-degree of polymerization maltodextrin with uniform degree of polymerization. Due to the limitations of the existing maltodextrin preparation methods, the existing technology has problems such as low starch solid content and no efficient separation of uniform polymerization degree maltodextrin. The existing technology uses polyethylene glycol to gradually precipitate dextrin components with molecular weights ranging from 5.443×10 3 ~3.297×10 4 Da. Although the components obtained by dextrin separation of this technology are uniform, the separation steps are cumbersome and time-consuming. Each time polyethylene glycol is added, it needs 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, this technology has low production intensity, which is not conducive to industrial production. Similarly, there is a prior art method for separating helicodextrin by alcohol and separating cyclodextrin using ethanol of different volume fractions. The cyclodextrin prepared from 10% starch milk as the raw material needs to stand for 12 hours at 4°C when separated by ethanol, and the minimum DP value prepared is only 40. The concentration of dextrin separated by this technology is also low, and it is also not suitable for the separation of dextrin with high solid content. In addition, the separation effect of this technology is general, and the degree of polymerization of dextrin is relatively large.

[0005] Therefore, there is an urgent need to develop a maltodextrin production method with high production intensity, high raw material yield and a certain uniformity. Summary of the invention

[0006] In view of the problems of low starch solid content, high viscosity, and low product yield due to insufficient enzymatic hydrolysis in the preparation of maltodextrin by traditional hydrothermal gelatinization and jet liquefaction, the present invention provides a method for preparing maltodextrin, which adopts high-temperature dry heat amorphization, enzymatic hydrolysis liquefaction, polyethylene glycol precipitation classification combined with alcohol complexation classification, membrane interception classification technology and hot air drying process. The present invention ensures large-scale and efficient preparation of maltodextrin products with high yield and uniform distribution of polymerization degree on the basis of processing high-solid content starch milk.

[0007] The first object of the present invention is to provide a method for preparing a maltodextrin product, characterized in that the method comprises the following steps:

[0008] (1) Dry heat amorphization: dry heat treatment of starch;

[0009] (2) Enzymatic liquefaction: The starch is prepared into a 35% to 40% (w / w) starch milk, and then enzymatically hydrolyzed and inactivated to obtain an enzymatic hydrolyzate;

[0010] (3) decolorization and impurity removal: decolorization and impurity removal of the enzymatic hydrolyzate obtained in step (2);

[0011] (4) classification: the decolorized and impurity-free enzymatic hydrolyzate obtained in step (3) is sequentially subjected to polyethylene glycol precipitation classification, ethanol complexation classification, and membrane interception classification to obtain maltodextrin components with different polymerization degree distributions;

[0012] (5) Drying: Drying the maltodextrin components with different polymerization degree distributions obtained in step (4) to obtain a maltodextrin product.

[0013] In one embodiment, the type of starch described in step (1) may include common corn starch or tapioca starch or potato starch.

[0014] In one embodiment, the step of dry heat amorphization is: spreading the starch in a steel plate to a thickness of 2 to 3 mm, and then subjecting it to dry heat treatment for 8 to 10 minutes, with the treatment temperature set at 180 to 200°C.

[0015] Optionally, the starch is spread on a steel plate to a thickness of 2 to 3 mm, and subjected to dry heat treatment for 8 minutes, with the treatment temperature set at 200°C.

[0016] Optionally, the starch milk concentration is 35% (w / w) or 40% (w / w).

[0017] In one embodiment, in step (2), the starch milk is kept at 65-70° C. for 4-6 minutes.

[0018] Optionally, in step (2), the starch milk is kept at 70° C. for 5 minutes.

[0019] In one embodiment, in step (2), the pH of the starch milk is 5.0, 10 to 20 U / g α-amylase is added, and the enzymatic hydrolysis is carried out for 5 to 10 minutes.

[0020] Optionally, in step (2), 10 U / g α-amylase is added to the starch milk and enzymatic hydrolysis is performed for 5 minutes.

[0021] In one embodiment, in step (3), 1% (w / v) activated carbon is added to the enzymatic hydrolyzate and the solution is kept at 80-90° C. for 15-30 minutes for decolorization.

[0022] In one embodiment, the centrifugal speed for collecting the supernatant by centrifugation in step (4) is 8000 r / min, and the centrifugal time is 10 min.

[0023] In one embodiment, the step of polyethylene glycol precipitation and fractionation in step (4) is as follows: mixing the enzymatic hydrolysate with 30% to 40% (w / v) polyethylene glycol 6000, and centrifuging to obtain fractionated component 1 and supernatant 1.

[0024] In one embodiment, the step of ethanol complexation fractionation in step (4) is: mixing the supernatant 1 with a 50% to 60% (v / v) anhydrous ethanol solution, and centrifuging to obtain fractionated components 2 and supernatant 2.

[0025] In one embodiment, the step (4) of membrane interception and fractionation is as follows: the supernatant 2 is separated using a hollow fiber membrane of 1000 to 2000 Da to intercept and obtain fractionated components 3.

[0026] Optionally, the molecular weight cutoff of the hollow fiber membrane in step (4) is 1000 or 2000 Da.

[0027] In one embodiment, hot air drying is used in step (5) at a temperature of 50 to 70°C.

[0028] Optionally, the hot air drying temperature is 50, 60 or 70°C.

[0029] The second object of the present invention is to provide a maltodextrin product prepared by the above method, and the use of the maltodextrin product in the preparation of food additives, special dietary functional ingredients, flavor substances or active molecule embedding carriers.

[0030] Beneficial Effects

[0031] Different from the traditional preparation of maltodextrin, the present invention uses dry heat amorphous technology to process starch, enzymatic hydrolysis of starch milk with high solid content (35% to 40%, w / w), decolorization with activated carbon after enzymatic hydrolysis, separation with polyethylene glycol precipitation classification combined with alcohol complexation classification and membrane interception classification technology, and hot air drying. On the basis of processing starch milk with high solid content, the present invention ensures large-scale and efficient preparation of maltodextrin products with high yield and uniform distribution of polymerization degree, and the yield of maltodextrin reaches more than 81%. The present invention obtains maltodextrin components with 3 DP value ranges, corresponding to different applications respectively.

[0032] The beneficial effects of the present invention are as follows:

[0033] (1) The present invention uses dry heat amorphization to treat starch, promotes starch declustering and gelatinization, and increases the starch milk solid content to 35% to 40%, thereby increasing production capacity, reducing concentration energy consumption, and being more suitable for large-scale production.

[0034] (2) The present invention sequentially uses polyethylene glycol precipitation classification combined with alcohol complexation classification and membrane interception classification technology to achieve the separation of maltodextrin with high solid content, while narrowing the distribution range of maltodextrin polymerization degree, obtaining maltodextrin products with uniform polymerization degree, and improving starch utilization rate, up to 82.6%.

[0035] (3) The present invention can realize batch drying of maltodextrin by hot air drying, saving energy consumption required for the concentration process, saving drying costs, and having significant environmental advantages.

[0036] (4) The maltodextrin graded components prepared by the present invention are component 1 DP>50±5, component 2 DP 30±5~50±5, and component 3 DP 10±5~30±5. Component 1 can be used as a functional ingredient for special diets; component 2 can be used as an embedding carrier for flavor substances and active molecules; and component 3 can be used as a food additive, which has great application potential. DETAILED DESCRIPTION

[0037] The preferred embodiments of the present invention are described below. It should be understood that the embodiments are for better explaining the present invention and are not used to limit the present invention.

[0038] Materials and Equipment

[0039] 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.

[0040] 1. Determination of starch hydrolysis rate (DE)

[0041] The DE value is the percentage of reducing sugars (calculated as glucose) on the dry matter of the syrup. Reducing sugars are measured according to the Lane-Eynon method and the results are used to calculate the DE content, expressed as a percentage of the total starch content.

[0042] Accurately weigh 0.5000g (dry basis) of maltodextrin, add 20mL of distilled water, stir magnetically at room temperature for 1h to fully dissolve it, dilute to a 50mL volumetric flask, shake well, and use it as the test solution. Take 1.0mL of the test solution in a test tube, add water to 2mL, add 3mL of DNS reagent, and place the mixture in a boiling water bath for 5min. Cool and dilute to 15mL, and measure the absorbance at 540nm.

[0043] 2. Determination of starch utilization

[0044] That is, the maltodextrin yield is expressed as the ratio of the total mass of maltodextrin obtained after drying to the mass of starch used.

[0045] 3. Determination of chain length distribution of maltodextrin

[0046] The chain length distribution of maltodextrin was determined by HPAEC-PAD. The pulsed amperometric detector model was ICS-5000+, the chromatographic column model was Dionex CarboPAC PA200, the mobile phase was NaOH solution (150 mmol / L), the flow rate was 0.4 mL / min, and the injection volume was 25 μL.

[0047] Example 1: Preparation and separation of maltodextrin

[0048] First, the corn starch was subjected to a 200°C dry heat amorphization treatment, a 40% (w / w) starch milk was prepared, and enzymatic hydrolysis was performed at 70°C. After enzymatic hydrolysis, activated carbon was used for decolorization, 40% (w / v) polyethylene glycol 6000 precipitation classification, 60% (v / v) ethanol complex classification, and membrane interception classification separation were performed, and maltodextrin products with different polymerization degrees were obtained by drying. The specific experimental steps are as follows:

[0049] (1) Dry heat amorphization: spread corn starch on a steel plate to a thickness of 2-3 mm, and then dry heat treat for 8 min at a temperature of 200 °C.

[0050] (2) Enzymatic liquefaction: The starch was adjusted to a starch milk with a content of 35% (w / w, dry starch basis accounting for the total weight of the starch milk), the pH was adjusted to 5.0, the mixture was kept at 70°C for 5 min, 10 U / g α-amylase was added, and the mixture was enzymatically hydrolyzed for 5 min;

[0051] (3) Inactivation of enzymes: After enzymatic hydrolysis, the pH of the solution is adjusted to 4.5 to inactivate the enzymes;

[0052] (4) Decolorization and impurity removal: The enzymatic hydrolyzate obtained in step (3) was added with 1% (w / v) activated carbon for decolorization at 80° C. for 30 min, and then heavy metal salts and pigments were removed by ion exchange resin;

[0053] (5) Classification: The enzymatic hydrolyzate obtained in step (4) is sequentially subjected to polyethylene glycol precipitation classification, ethanol complexation classification, and membrane interception classification to obtain a maltodextrin component with a uniform degree of polymerization distribution:

[0054] Polyethylene glycol precipitation classification: the filtrate was mixed with 40% (w / v) polyethylene glycol 6000, stirred thoroughly and then allowed to stand for 2 hours, and centrifuged at 8000 r / min for 10 minutes. The resulting precipitate was maltodextrin fraction 1, and its DP value was >50;

[0055] Ethanol complexation fractionation: the supernatant of polyethylene glycol precipitation fractionation was mixed with 60% (v / v) anhydrous ethanol solution, allowed to stand for 30 min, and centrifuged at 8000 r / min for 10 min. The resulting precipitate was maltodextrin fractionation component 2;

[0056] Membrane interception separation is to use a hollow fiber membrane with a molecular weight cutoff of 2000Da to separate the supernatant obtained by ethanol complexation fractionation to obtain maltodextrin fraction 3;

[0057] (6) Drying: Component 1, component 2, and component 3 collected in step (5) are dried by hot air to obtain three groups of maltodextrins with uniform polymerization degree.

[0058] The results are shown in Tables 1 and 2. The starch utilization rate, i.e., the maltodextrin yield, can reach 82.1%. The chain lengths of maltodextrin fractions 1, 2, and 3 are distributed in DP>50, DP 30-50, and DP 10-30, respectively.

[0059] Example 2: Preparation and separation of maltodextrin

[0060] First, the corn starch was subjected to a 180°C dry heat amorphization treatment, and a 35% (w / w) starch milk was prepared, and then enzymatic hydrolysis was performed at 65°C. After enzymatic hydrolysis, activated carbon was used for decolorization, 30% (w / v) polyethylene glycol 6000 precipitation classification, 50% (v / v) ethanol complex classification, and membrane interception classification separation were performed, and then dried to obtain maltodextrin products with different polymerization degrees. The specific experimental steps are as follows:

[0061] (1) Dry heat amorphization: spread the corn starch on a steel plate to a thickness of 2-3 mm, and then dry heat treat it for 10 min at a temperature of 180 °C.

[0062] (2) Enzymatic liquefaction: The starch was adjusted to 35% (w / w, dry starch basis accounts for the total weight of starch milk) starch milk, the pH was adjusted to 5.0, the mixture was kept at 65°C for 5 min, 20 U / g α-amylase was added, and the mixture was enzymatically hydrolyzed for 10 min;

[0063] (3) Inactivation of enzymes: After enzymatic hydrolysis, the pH of the solution is adjusted to 4.5 to inactivate the enzymes;

[0064] (4) Decolorization and impurity removal: The enzymatic hydrolyzate obtained in step (3) was added with 1% (w / v) activated carbon for decolorization at 80° C. for 30 min, and then heavy metal salts and pigments were removed by ion exchange resin;

[0065] (5) Classification: The enzymatic hydrolyzate obtained in step (4) is sequentially subjected to polyethylene glycol precipitation classification, ethanol complexation classification, and membrane interception classification to obtain a maltodextrin component with a uniform degree of polymerization distribution:

[0066] Polyethylene glycol precipitation classification: the filtrate was mixed with 30% (w / v) polyethylene glycol, stirred thoroughly and then allowed to stand for 2 hours, and centrifuged at 8000 r / min for 10 minutes. The resulting precipitate was maltodextrin fraction 1;

[0067] Ethanol complexation fractionation: the supernatant of polyethylene glycol precipitation fractionation was mixed with 50% (v / v) anhydrous ethanol solution, allowed to stand for 30 min, and centrifuged at 8000 r / min for 10 min. The resulting precipitate was maltodextrin fractionation component 2;

[0068] Membrane interception separation is to use a hollow fiber membrane with a molecular weight cutoff of 2000Da to separate the supernatant obtained by ethanol complexation fractionation to obtain maltodextrin fraction 3;

[0069] (6) Drying: Component 1, component 2, and component 3 collected in step (5) are dried by hot air to obtain three groups of maltodextrins with uniform polymerization degree.

[0070] The results are shown in Tables 1 and 2. The starch utilization rate, i.e., the maltodextrin yield, can reach 81.5%. The chain lengths of maltodextrin fractions 1, 2, and 3 are distributed in DP>60, DP 40-60, and DP 10-40, respectively.

[0071] Example 3: Preparation and separation of maltodextrin

[0072] First, cassava starch was subjected to a 180°C dry heat amorphization treatment, 40% (w / w) starch milk was prepared, enzymatic hydrolysis was performed at 70°C, activated carbon was used for decolorization after enzymatic hydrolysis, 30% (w / v) polyethylene glycol precipitation classification, 60% (v / v) ethanol complexation classification and membrane interception classification were performed, and maltodextrin products with different polymerization degrees were obtained by drying. The specific experimental steps are as follows:

[0073] (1) Dry heat amorphization: Cassava starch was spread on a steel plate to a thickness of 2 to 3 mm, and then dry heat treated for 10 min at a temperature of 180 °C.

[0074] (2) Enzymatic liquefaction: starch was adjusted to 40% (w / w, dry starch basis to the total weight of starch milk) starch milk, pH was adjusted to 5.0, kept at 70°C for 5 min, 20 U / g α-amylase was added, and enzymatic hydrolysis was performed for 10 min;

[0075] (3) Inactivation of enzymes: After enzymatic hydrolysis, the pH of the solution is adjusted to 4.5 to inactivate the enzymes;

[0076] (4) Decolorization and impurity removal: The enzymatic hydrolyzate obtained in step (3) was added with 1% (w / v) activated carbon for decolorization at 80°C for 30 min, and then heavy metal salts and pigments were removed by ion exchange resin.

[0077] (5) Classification: The enzymatic hydrolyzate obtained in step (4) is sequentially subjected to polyethylene glycol precipitation classification, ethanol complexation classification, and membrane interception classification to obtain a maltodextrin component with a uniform degree of polymerization distribution:

[0078] Polyethylene glycol precipitation classification: the enzymatic hydrolysate was mixed with 30% (w / v) polyethylene glycol, stirred thoroughly and then allowed to stand for 2 hours, and centrifuged at 8000 r / min for 10 minutes. The resulting precipitate was the maltodextrin fraction 1;

[0079] Ethanol complexation fractionation: the supernatant of polyethylene glycol precipitation fractionation was mixed with 60% (v / v) anhydrous ethanol solution, allowed to stand for 30 min, and centrifuged at 8000 r / min for 10 min. The resulting precipitate was maltodextrin fractionation component 2;

[0080] The membrane separation is to use a hollow fiber membrane with a molecular weight cutoff of 1000Da to separate the supernatant obtained by ethanol complexation fractionation to obtain maltodextrin fraction 3.

[0081] (6) Drying: Component 1, component 2, and component 3 collected in step (5) are dried by hot air to obtain three groups of maltodextrins with uniform polymerization degree.

[0082] The results are shown in Tables 1 and 2. The starch utilization rate, i.e., the maltodextrin yield, can reach 82.6%. The chain lengths of maltodextrin fractions 1, 2, and 3 are distributed in DP>55, DP 25-55, and DP 5-25, respectively.

[0083] Comparative Example 1: Preparation of maltodextrin by hydrothermal gelatinization

[0084] On the basis of Example 1, step (1) of dry heat amorphization was changed to starch milk gelatinization in boiling water bath for 30 min, and other conditions or parameters were the same as those in Example 1. As shown in Table 2, the starch utilization rate, i.e., the yield of maltodextrin, was reduced to 33.2%, which was much lower than that in Example 1. This is because the starch milk had a high viscosity under the hydrothermal gelatinization condition, which hindered the diffusion and contact between the enzyme and the substrate during the subsequent enzymatic hydrolysis reaction, and the reaction rate was reduced.

[0085] Comparative Example 2: Preparation of maltodextrin by jet liquefaction

[0086] On the basis of Example 1, the dry heat amorphization operation in step (1) of Example 1 was omitted, and in step (2) of Example 1, the starch was gelatinized by jet liquefaction, that is, 10U / g α-amylase was added to obtain a liquefied liquid by jet liquefaction, and the jet liquefaction material pressure was set to 0.35MPa, the steam pressure was 0.1MPa, the temperature was 80-90°C, the time was 8min, and then kept warm at 70°C for 5min, and other conditions or parameters were consistent with those in Example 1. The results are shown in Table 2. Compared with Example 1, the maltodextrin yield was reduced to 67.7%. This is because the gelatinization and enzymolysis of starch started simultaneously during the jetting process, and the complete gelatinization rate of the substrate starch was low, resulting in a decrease in starch utilization. In addition, the addition of the jet liquefaction operation increased the energy consumption and economic cost of maltodextrin production.

[0087] Comparative Example 3: Preparation of maltodextrin without classification

[0088] On the basis of Example 1, the classification in step (5) of Example 1 was omitted, and other conditions or parameters were the same as those in Example 1. The results are shown in Table 2. Compared with Example 1, the molecular weight distribution of the product maltodextrin was uneven, and the DP distribution was 1 to 70. The maltodextrin produced was a mixture of various substances including glucose, maltose, oligosaccharides and polysaccharides, and glucose and maltose had high reducing properties. When they coexisted with amino acids or proteins, they were prone to Maillard reaction, which reduced the product quality of maltodextrin.

[0089] In addition, the three groups of maltodextrin components obtained after graded separation can be quickly dried by hot air drying technology. Compared with the concentration and spray drying technology required for the preparation of unfractionated maltodextrin, it saves drying costs, and the improvement of polymerization degree uniformity is beneficial to the stability of its industrial application.

[0090] Comparative Example 4: Preparation of maltodextrin, single use of polyethylene glycol precipitation and classification

[0091] On the basis of Example 1, the classification step in step (5) of Example 1 is changed to:

[0092] 40% (w / v) polyethylene glycol precipitation classification: the enzymatic hydrolysate was mixed with 40% (w / v) polyethylene glycol, stirred thoroughly and then allowed to stand for 2 hours, and centrifuged at 8000 r / min for 10 minutes. The resulting precipitate was maltodextrin fraction 1;

[0093] 50% (w / v) polyethylene glycol precipitation fractionation: The supernatant obtained by 40% (w / v) polyethylene glycol precipitation fractionation was further mixed with 50% (w / v) polyethylene glycol, stirred thoroughly and allowed to stand for 2 hours.

[0094] Other conditions or parameters are the same as those in Example 1. Compared with Example 1, only two groups of maltodextrin components with DP>50 and DP 1-50 can be obtained. Although the yield is higher, the separation effect is poor. Specifically: Among the maltodextrin products obtained by single polyethylene glycol precipitation and grading, only the maltodextrin component with DP>50 can be used to prepare special dietary functional ingredients, while the maltodextrin component with DP1-50 is not only poor for the embedding effect of flavor components and active substances, but also does not have good transparency and solubility, and contains small molecular reducing sugars that are easy to absorb moisture and undergo browning reaction.

[0095] This is because the DP of the maltodextrin component in the supernatant obtained after precipitation and fractionation with the addition of 40% (w / v) polyethylene glycol is less than 50. If polyethylene glycol is continued to be added, the reaction system cannot precipitate maltodextrin by centrifugation due to the increased viscosity to narrow the distribution range of the product's degree of polymerization.

[0096] Comparative Example 5: Preparation of maltodextrin using only alcohol complexation and classification technology

[0097] On the basis of Example 1, the classification step in step (5) of Example 1 is changed to:

[0098] 30% (v / v) ethanol complexation fractionation: the filtrate was mixed with 30% (w / v) ethanol, allowed to stand for 30 min, and centrifuged at 8000 r / min for 10 min. The resulting precipitate was maltodextrin fractionation component 1;

[0099] 60% (v / v) ethanol complexation fractionation: The supernatant obtained by 30% (v / v) ethanol precipitation fractionation was mixed with 60% (v / v) anhydrous ethanol solution, allowed to stand for 30 min, and centrifuged at 8000 r / min for 10 min. The resulting precipitate was maltodextrin fractionation component 2;

[0100] 80% (v / v) ethanol complexation fractionation: The supernatant obtained by 60% (v / v) ethanol precipitation fractionation was mixed with 80% (v / v) anhydrous ethanol solution, allowed to stand for 30 min, and centrifuged at 8000 r / min for 10 min. The resulting precipitate was maltodextrin fractionation component 3.

[0101] Other conditions or parameters are the same as those in Example 1. Compared with Example 1, the starch utilization rate, i.e., the maltodextrin yield, is reduced to 65.5%. This is because the volume of the maltodextrin solution increases significantly and the concentration decreases during the addition of alcohol, while the separation, precipitation and drying costs increase, and the yield of the product maltodextrin decreases.

[0102] Comparative Example 6: Preparation of maltodextrin using only membrane interception and classification technology

[0103] On the basis of Example 1, the classification step in step (5) of Example 1 is changed to:

[0104] Hollow fiber membranes with molecular weight cutoffs of 10000, 5000 and 2000 Da were used to separate the enzymatic hydrolysate to obtain maltodextrin fractions 1, 2 and 3.

[0105] Other conditions or parameters are the same as those in Example 1. Compared with Example 1, the starch utilization rate, i.e., the maltodextrin yield, is reduced to 58.4%. This is because the high substrate concentration maltodextrin solution is difficult to intercept when using membrane separation, resulting in a reduced yield of the product maltodextrin. At the same time, the amount of hollow fiber membrane used in the separation process is large, the loss of maltodextrin increases, and the cost of the hollow fiber membrane increases.

[0106] Comparative Example 7: Preparation of maltodextrin, changing the order of fractionation

[0107] On the basis of Example 1, the order of the classification steps in step (5) of Example 1 is changed to:

[0108] Ethanol complexation fractionation: the enzymatic hydrolyzate was mixed with 80% (v / v) anhydrous ethanol solution, allowed to stand for 30 min, and centrifuged at 8000 r / min for 10 min. The resulting precipitate was maltodextrin fractionation component 1;

[0109] Polyethylene glycol precipitation classification: the filtrate obtained by ethanol complex classification was mixed with 30% (w / v) polyethylene glycol, stirred thoroughly and then allowed to stand for 2 hours, and centrifuged at 8000 r / min for 10 minutes. The obtained precipitate was maltodextrin classification component 2;

[0110] The membrane cut-off separation is to use a hollow fiber membrane with a molecular weight cut-off of 2000Da to separate the supernatant obtained by ethanol complexation fractionation to obtain maltodextrin fractionation component 3.

[0111] Other conditions or parameters are the same as those in Example 1. Compared with Example 1, only two groups of maltodextrin components with chain lengths distributed in DP>30 and DP 10-30 can be obtained. Adjusting the order of the classification steps results in the inability to narrow the distribution range of the degree of polymerization of maltodextrin with DP>30, and the maltodextrin components with DP>50 and DP 30-50 cannot be separated. This is because it is difficult for polyethylene glycol to precipitate maltodextrin components with smaller molecular weights. The use of 60% (v / v) ethanol complexation classification will cause the maltodextrin components with smaller DP values ​​to precipitate together with the components with larger DP, resulting in the separated maltodextrin components with DP>30. At this time, the polyethylene glycol precipitation technology is used to classify the maltodextrin components with DP<30 in the filtrate obtained by ethanol complexation classification, and there is no significant separation effect.

[0112] Only the maltodextrin component with a DP of 10 to 30 obtained by this sequential separation can be used for encapsulation of flavor components and active substances, while the component with DP>30 cannot be separated into components with DP>50 and DP 30 to 50, so it has a poor effect as a special dietary functional ingredient and cannot be used to encapsulate flavor components, active substances, etc.

[0113] Table 1 Maltodextrin chain length distribution

[0114]

[0115]

[0116] Note: DP stands for degree of polymerization

[0117] Table 2 Maltodextrin yield

[0118]

[0119]

[0120] From the data in Table 1 and Table 2, we can see that

[0121] (1) Compared with Example 1 and Comparative Example 3, the polymerization degree of the maltodextrin products after fractionation and separation is uniform. The DP of the unseparated maltodextrin is between 1 and 70. The maltodextrin products after fractionation and separation are divided into three groups: DP>50, DP 30-50, and DP 10-30.

[0122] (2) Compared with Examples 1 to 3 and Comparative Examples 1 and 2, the maltodextrin prepared by dry heat amorphization has a lower DE value and improves the utilization rate of starch to more than 80%;

[0123] (3) Compared with Example 1 and Comparative Examples 4 to 7, the starch utilization rate of using polyethylene glycol precipitation classification, ethanol complexation classification and membrane interception classification in sequence is higher than using only one of the separation methods or changing the order of the classification steps, and the separation effect is better.

[0124] Polyethylene glycol has a good classification effect on macromolecular maltodextrin and can effectively precipitate maltodextrin components with DP>50; ethanol complexation technology can effectively separate maltodextrin components with DP>30, but cannot separate maltodextrin components with DP<15; in order to save solvent consumption and drying costs, membrane separation and filtration of maltodextrin components with DP<10 are selected. The combination of the three can obtain three groups of maltodextrin components with chain lengths distributed in DP>50±5, DP 30±5~50±5, and DP 10±5~30±5, and each component has a corresponding range of use, which effectively narrows the distribution range of polymerization degree and saves costs.

[0125] 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 principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preparing maltodextrin, characterized in that: The method comprises the following steps: (1) Dry heat amorphization: dry heat treatment of starch; (2) Enzymatic liquefaction: The starch is prepared into a 35% to 40% w / w starch milk, and then enzymatically hydrolyzed and inactivated to obtain an enzymatic hydrolyzate; (3) Decolorization and impurity removal: decolorizing and impurity removal of the enzymatic hydrolyzate obtained in step (2); (4) classification: the decolorized and impurity-free enzymatic hydrolysate obtained in step (3) is sequentially subjected to polyethylene glycol precipitation classification, ethanol complexation classification and membrane interception classification to obtain maltodextrin components with different polymerization degree distributions; The polyethylene glycol precipitation and fractionation steps are as follows: mixing the enzymatic hydrolysate with 30% to 40% w / v polyethylene glycol, and centrifuging to obtain fractionated component 1 and supernatant 1; The steps of ethanol complexation fractionation are as follows: mixing supernatant 1 with 50% to 60% v / v anhydrous ethanol solution, and centrifuging to obtain fractionated component 2 and supernatant 2; The steps of membrane interception and fractionation are as follows: the supernatant 2 is separated using a 1000-2000 Da hollow fiber membrane to intercept and obtain component 3; (5) Drying: Drying the maltodextrin component obtained in step (4) to obtain maltodextrin with different polymerization degree distributions.

2. The method according to claim 1, characterized in that The step (1) of dry heat amorphization is to treat the starch at 180-200° C. for 8-10 min.

3. The method according to claim 1, characterized in that: In step (2), the starch milk is hydrolyzed at 65-70°C and kept warm for 4-6 minutes.

4. The method according to claim 1, characterized in that In step (2), 10-20 U / g α-amylase is added to the starch milk and enzymolysis is performed for 5-10 min.

5. The method according to claim 1, characterized in that In step (5), hot air drying is used at a temperature of 50-70°C.

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