Method for preparing low-GI maltodextrin by means of synergy of double enzymes

Abstract

The present invention belongs to the field of starch biotechnology, and relates to a method for preparing low-GI maltodextrin by means of the synergy of double enzymes. The method of the present invention comprises: dispersing starch particles in water to obtain starch milk; adding a starch branching enzyme Ro-GBE to the starch milk, heating same for gelatinization, cooling same and then performing a constant-temperature reaction to obtain a reaction liquid 1; cooling the reaction liquid 1, adding β-amylase, and reacting same with yeast to obtain a reaction liquid 2; and drying the reaction liquid 2 to obtain low-GI maltodextrin. In the present invention, the branching degree of the product modified by means of an enzymic method is increased, the relative molecular mass is reduced, and a highly-branched small molecular structure is formed, thereby delaying the digestibility of the product and enhancing the solubility and the solution stability of the product. In the present invention, by using the starch branching enzyme and the β-amylase to perform synergistic secondary enzymolysis modification on the starch, fast digestion components in the product can be reduced by 42.71%, the product is soluble in cold water, and the transparency of the solution can still reach 90.00% or higher after storage at 4°C for 30 d.

Description

Method for preparing low GI malt dextrin by double-enzyme synergistic method TECHNICAL FIELD

[0001] The present application relates to a method for preparing low GI malt dextrin by double-enzyme synergistic method, belonging to the field of starch biotechnology. BACKGROUND

[0002] Glycemic index (GI) is an index that can reflect the level of postprandial blood glucose response, which is defined as the ratio of the area under the blood glucose response curve within a period of time (≥2h) after eating food containing 50g available carbohydrates to the area under the blood glucose response curve after eating the same amount of standard food (50g starch white bread or 50g glucose). Studies have shown that the intake of easily digestible high GI food by the human body can cause blood glucose to rise sharply, promote the secretion and release of insulin, and accelerate the conversion of blood glucose into fat, thereby leading to high blood lipids and obesity, and obesity is a high-risk factor for diseases such as hypertension and diabetes. Severe blood glucose fluctuations can also activate the body's oxidative stress pathway, promote local inflammatory reactions, cause vascular epithelial cell damage, and thus induce diseases such as coronary heart disease, stroke, retinopathy, and kidney disease. On the contrary, the intake of low GI food by the human body can prolong the digestion and absorption or anabolism time of starch and sugar, slowly and continuously release energy, reduce the burden on the islets, and help maintain postprandial blood glucose balance, thereby controlling body weight and preventing the occurrence of various chronic diseases.

[0003] Starch is the most important carbohydrate component in human diet, and its large intake is the main reason for blood glucose rise. Reducing starch digestibility is beneficial to maintaining postprandial glucose homeostasis and has unique efficacy in preventing chronic diseases. At present, the methods commonly used to reduce starch digestibility mainly include physical modification, chemical modification, enzymatic modification, and composite modification. Among them, the biological enzyme method modification has the characteristics of high reaction efficiency and mild reaction conditions, and is suitable for large-scale industrial production. Current research mainly uses maltase, alpha-amylase, beta-amylase, pullulanase and other hydrolytic enzymes or starch branching enzyme, 4,6-alpha-glucosyltransferase and other glycosyltransferases to regulate the digestion characteristics of starch. After being catalyzed by these enzymes alone or in combination, the digestion rate of starch in vivo and in vitro is significantly slowed down, the GI value is lowered, and the relative molecular mass is also lowered, which is more in line with the definition of "dextrin".

[0004] Low GI maltodextrin, as a low glycemic index starch derivative, has a slow digestion rate and can slowly release glucose into the blood, causing moderate postprandial blood glucose changes and insulin response, thereby reducing fasting and postprandial blood glucose levels and regulating the metabolic homeostasis of insulin in the body, improving disease-induced glucose metabolism disorders, and being beneficial to reducing postprandial blood glucose and improving blood lipids. It has certain auxiliary therapeutic effect on some diet-related chronic diseases such as type 2 diabetes, cardiovascular disease and obesity, etc. However, at present, there are still few related researches on low GI maltodextrin, and only a few slowly digestible starch and its derivative products are commercialized in foreign countries, and the domestic market is still a blank. Therefore, it is of great significance to explore the efficient preparation method of low GI maltodextrin and improve its preparation efficiency for promoting the industrialization development of low GI maltodextrin.

[0005] In the previous study, the inventors' research group disclosed a method for preparing slowly digestible maltodextrin in the patent with the authorization number CN112852906A. The preparation process is as follows: using starch branching enzyme Ro-GBE derived from Rhodothermus obamensis STB05 and starch branching enzyme Gt-GBE derived from Geobacillus thermoglucosidans STB02 to act on granular starch and gelatinized starch in turn, and exerting the synergistic effect of the two starch branching enzymes to improve the slow digestion performance of the product. However, this process needs to precisely control the action time of granular starch, and the slow digestion performance of the product still has a large improvement space. Moreover, there are problems such as complex process, large reaction viscosity, poor solubility and stability of the product, which cannot meet the actual application requirements.

[0006] Therefore, in order to further improve the slow digestion characteristics of low GI maltodextrin and improve its solution stability, it is urgent to explore a method for efficiently preparing low GI maltodextrin with high stability. SUMMARY

[0007] In order to solve the above problems, the present application provides a method for preparing low GI maltodextrin by double enzyme synergy. The present application establishes a process for efficiently preparing low GI maltodextrin by synergistically modifying starch with starch branching enzyme and beta-amylase. The branched degree of the product modified by enzyme method is increased, the relative molecular mass is reduced, and a high-branched small molecular structure is formed, thereby delaying the digestibility of the product and enhancing the solubility and solution stability of the product. The present application uses starch branching enzyme and beta-amylase to synergistically modify starch, which has a significant effect, can reduce the fast-digesting component in the product by 42.71%, the product is cold water soluble, and the transparency of the solution can still reach more than 90.00% after being stored at 4℃ for 30d.

[0008] The present application is realized by the following technical solutions:

[0009] A first object of the present application is to provide a method for preparing low GI maltodextrin by two-enzyme synergistic method, which comprises the following steps:

[0010] (1) dispersing starch granules in water to obtain starch milk; adding starch branching enzyme Ro-GBE to the obtained starch milk, and performing gelatinization reaction by heating, and then performing constant temperature reaction after cooling to obtain reaction liquid 1;

[0011] (2) adding β-amylase and yeast to the reaction liquid 1 obtained in step (1) after cooling, and performing reaction to obtain reaction liquid 2; the yeast is added for sugar removal treatment;

[0012] (3) drying the reaction liquid 2 obtained in step (2) to obtain the low GI maltodextrin.

[0013] In an embodiment of the present application, in step (1), the starch is selected from one or more of cassava starch, common corn starch, waxy corn starch, potato starch, rice starch and wheat starch.

[0014] In an embodiment of the present application, in step (1), the concentration of the starch milk is 10%-30% (w / w), preferably 15% (w / w); and the pH value of the starch milk is 6.0-8.0.

[0015] In an embodiment of the present application, in step (1), the starch branching enzyme Ro-GBE is derived from Rhodothermus obamensis STB05, and the nucleotide sequence is shown in SEQ ID NO. 1.

[0016] In an embodiment of the present application, in step (1), the addition amount of the starch branching enzyme Ro-GBE is 100 U / g-1000 U / g dry starch, preferably 100 U / g-600 U / g dry starch.

[0017] In an embodiment of the present application, in step (1), the temperature of the gelatinization reaction is 70℃-95℃; and the time of the gelatinization reaction is 0h-5h.

[0018] In an embodiment of the present application, in step (1), the temperature of the constant temperature reaction is 60℃-80℃; and the time of the constant temperature reaction is 8h-48h, preferably 8h-24h.

[0019] In an embodiment of the present application, in step (2), the temperature after cooling is 30℃-60℃.

[0020] In one embodiment of the present application, in step (2), the beta-amylase is added in an amount of 100 U / g to 1000 U / g of dry starch; preferably, 100 U / g to 500 U / g of dry starch.

[0021] In one embodiment of the present application, in step (2), the yeast is added in an amount of 0.5% to 5%.

[0022] In one embodiment of the present application, in step (2), the reaction is carried out at a temperature of 30°C to 60°C, preferably 30°C to 37°C, for a time period of 6h to 72h, preferably 12h to 60h.

[0023] In one embodiment of the present application, in step (2), the reaction is followed by a secondary reaction with the addition of beta-amylase and yeast.

[0024] In one embodiment of the present application, the beta-amylase is added in an amount of 100 U / g to 1000 U / g of dry starch; preferably, 100 U / g to 500 U / g of dry starch.

[0025] In one embodiment of the present application, the yeast is added in an amount of 0.5% to 5%.

[0026] In one embodiment of the present application, the secondary reaction is carried out at a temperature of 30°C to 60°C, preferably 30°C to 37°C, for a time period of 6h to 72h, preferably 12h to 60h.

[0027] In one embodiment of the present application, in step (2), the reaction is followed by enzyme inactivation, filtration, decolorization and ion exchange treatment.

[0028] In one embodiment of the present application, in step (2), after the reaction is completed, the temperature is raised for enzyme inactivation, and the yeast cells and impurities are removed by filtration using a 0.22 μm to 0.45 μm filter membrane.

[0029] In one embodiment of the present application, the decolorization is carried out by adjusting the pH of the clear solution obtained by filtration, adding activated carbon and stirring to decolorize, to obtain a decolorized solution.

[0030] And / or, the ion exchange is carried out by using an ion exchange resin to remove metal salts and pigments from the decolorized solution.

[0031] In one embodiment of the present application, the ion exchange resin is a strong acid cation-weak base cation-strong acid cation exchange resin, and the reaction temperature for ion exchange is 40°C to 50°C.

[0032] In one embodiment of the present application, the pH value of the clarified solution is adjusted to 4.0-5.0, the activated carbon is added in an amount of 1%, and the decolorization is carried out at 40-50°C for 15-30 min.

[0033] In one embodiment of the present application, in step (3), the drying is selected from one or more of freeze drying, drum drying and spray drying.

[0034] A second object of the present application is to provide the low GI maltodextrin prepared by the method.

[0035] A third object of the present application is to provide the use of the low GI maltodextrin in special medical use formula food, probiotic product, health product, meal replacement product or pharmaceutical product.

[0036] The above technical solution of the present application has the following advantages compared with the prior art:

[0037] 1. The present application provides a method for preparing low GI maltodextrin by two enzymes in cooperation. The present application uses two different types of amylases to cooperatively modify starch to prepare low GI maltodextrin. The raw materials are easy to obtain, the process is simple, the operation is convenient, and the product yield is high. No other chemical groups are introduced, and no other types of glycosidic bonds are produced. Only the hydrolysis of the internal α-1, 4-glycosidic bonds and the reassembly of the α-1, 6-glycosidic bonds of the starch molecules occur, so the product is highly safe.

[0038] 2. The present application fully utilizes the catalytic characteristics of the two amylases, achieves the purpose of synergistic effect, further enhances the reaction efficiency, can significantly reduce the fast digestibility of the product, and improves the solubility and solution stability. A low GI maltodextrin with a slow digestion component ratio of 20.33% and a resistant component of 36.96% is prepared, and the fast digestion component ratio is reduced to 42.71%, which is reduced by 56.03% compared with natural starch, and the slow digestion and resistant component ratios are increased by 6.85 times and 126.45 times, respectively.

[0039] 3. The present application further improves the branching degree of the product and reduces the relative molecular mass of the product. The obtained product is soluble in cold water, the dissolution rate is better than that of the commercially available maltodextrin, and the solution transparency and viscosity stability are further improved. The transparency of the solution can still reach more than 90.00% after being stored at 4°C for 30d, which makes up for the shortcomings of natural starch that is not soluble in cold water and the poor solution stability and easy retrogradation of commercially available maltodextrin, and realizes the simultaneous improvement of the slow digestion performance and stability of the product. BRIEF DESCRIPTION OF DRAWINGS

[0040] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed in the embodiments or prior art description. Obviously, the drawings in the following description only constitute some embodiments of the present application, and for those skilled in the art, other drawings can also be obtained from these drawings without creative effort.

[0041] Figure 1 is the transparency change of different dextrin solutions in the test example of the present application after being stored at 4℃ for 30 days. DETAILED DESCRIPTION

[0042] The following will further illustrate the present application with specific examples. These examples are only used to illustrate the present application and not used to limit the scope of the present application. In addition, after reading the content taught by the present application, those skilled in the art can make various modifications or changes to the present application, and these equivalent forms also fall within the scope defined by the claims attached hereto.

[0043] In the present application, the term "low GI maltodextrin" refers to a maltodextrin modified by enzyme method, with a glycemic index (GI) lower than 55, and slower digestion and absorption characteristics compared with traditional maltodextrin (GI value is usually between 85-110). In the low GI maltodextrin prepared in the embodiments of the present application, the slow digestion component reaches 20.33%, the resistant component reaches 36.96%, and the fast digestion component ratio is reduced to 42.71%.

[0044] In the present application, the term "gelatinization reaction" refers to the process in which starch is swollen by water and the crystal structure is destroyed under the joint action of heat and water, and finally a viscous colloidal solution is formed.

[0045] In the present application, the term "fast digestion component" refers to the starch part that is completely hydrolyzed and released as glucose within 20 minutes of the substrate being added to a reaction system containing trypsin-starch glucosidase at 37℃ and pH 5.2 in the in vitro simulated digestion assay.

[0046] In the present application, the term "slow digestion component" refers to the starch part that is slowly and completely hydrolyzed and released as glucose within 20-120 minutes of the substrate being added to a reaction system containing trypsin-starch glucosidase at 37℃ and pH 5.2 in the in vitro simulated digestion assay.

[0047] In the present application, the term "resistant component" refers to the part of starch that cannot be hydrolyzed after 120 minutes of the substrate being added to a reaction system containing trypsin-starch glucosidase at 37℃ and pH 5.2 in the in vitro simulated digestion assay, but can be fermented by microorganisms in the colon and partially degraded.

[0048] In the present application, the term "normal corn starch" refers to a kind of starch prepared by processing corn, which mainly includes amylose and amylopectin, wherein the amylose accounts for about 28%, and the amylopectin accounts for about 72%.

[0049] In the present application, the term "waxy corn starch" refers to a kind of starch prepared by processing waxy corn, and the content of amylopectin is more than 95%.

[0050] The nucleotide sequence used in the present application is as follows:

[0051] The detection method used in the following examples is as follows:

[0052] (1) In vitro simulated digestion assay:

[0053] Mix 50 mg pepsin with 10 mL HCl (0.05 mol / L) solution, vortex for 5 min to mix thoroughly, and prepare pepsin solution, which is stored in ice bath and used immediately. Mix 3 g porcine pancreatin with 20 mL deionized water, vortex for 5 min to mix thoroughly, and centrifuge at 3500 g for 10 min at 4℃, take 15 mL supernatant, mix with 0.8 mL starch glucosidase to prepare mixed enzyme solution, which is stored in ice bath and used immediately.

[0054] The in vitro digestion test was performed according to the Englyst method with slight modifications: 100 mg of the sample to be tested (calculated on a dry basis) was accurately weighed and dispersed in 2.5 mL of a sodium acetate buffer (0.25 mol / L, pH 5.2), and the sample was thoroughly gelatinized by heating in a boiling water bath for 30 min. Then, 15 glass beads were added, and the sample was preheated at 37°C for 10 min on a water bath shaker at 160 r / min. Subsequently, 1.67 mL of a pepsin solution was added, and the reaction was shaken for 30 min to simulate the gastric digestion process. After the gastric digestion was completed, 2.5 mL of a sodium acetate buffer (pH 5.2) was added, and the reaction was continued for 30 min, and 0.83 mL of a mixed enzyme solution was added to simulate the intestinal digestion process. At 20 min and 120 min of the simulated intestinal digestion, 200 μL of the digestion solution was taken and added to 5 mL of 66.6% ethanol to terminate the reaction. After the mixture was centrifuged at 3500 g at room temperature for 5 min, 0.05 mL of the supernatant was accurately taken, and the glucose content was determined by the glucose oxidase method, and the proportions of rapidly digestible starch (RDS), slowly digestible starch (SDS), and resistant starch (RS) components were calculated. The specific calculation formulas are as follows: RDS (%) = G20 x 0.9 x 100 SDS (%) = (G120 - G20) x 0.9 x 100 RS (%) = 100 - RDS - SDS

[0055] wherein G20 represents the proportion of glucose produced by the sample after 20 min of digestion, and G120 represents the proportion of glucose produced by the sample after 120 min of digestion.

[0056] (2) Determination of β-amylase hydrolysis rate:

[0057] 10 mg of the sample was accurately weighed, and a sample solution of 5 mg / mL was prepared using a phosphate buffer (50 mmol / L, pH 5.5), and the sample was thoroughly gelatinized by heating in a boiling water bath for 30 min. After the sample solution was incubated in a 50°C water bath for 15 min, 10 U / mg and 30 U / mg of β-amylase were added, respectively, and the reaction was maintained at 50°C for 24 h. After the reaction was completed, the reaction was terminated by boiling in a water bath for 30 min. After the solution was filtered through a 0.22 μm water filter membrane, the maltose content in the solution was analyzed by ICS-5000 high-performance anion exchange chromatography-pulsed amperometric detector (HPAEC-PAD), and the β-amylase hydrolysis rate was calculated.

[0058] (3) Determination of relative molecular weight:

[0059] Accurately weigh 10 mg of sample, prepare a sample solution of 10 mg / mL with deionized water, and heat in a boiling water bath for 30 min to fully gelatinize the sample. The molecular weight distribution and weight-average molecular mass (Mw) of the sample were analyzed by a Dawn Heleos II high-performance volume exclusion chromatography-multiple-angle laser light scattering-differential refractometer (HPSEC-MALLS-RI).

[0060] The experimental methods used in the following examples are conventional methods unless otherwise specified, and the materials, reagents, etc. used are commercially available unless otherwise specified.

[0061] The starch branching enzyme Ro-GBE is derived from Rhodothermus obamensis STB05 (see literature: Wang Z, Xin C, et al. Expression and characterization of an extremely thermophilic 1,4-alpha-glucan branching enzyme from Rhodothermus obamensis STB05. Protein Expression and Purification [Elsevier]. 2019, 164: 105478-105478).

[0062] The beta-amylase (item number M-100H) is purchased from Shandong Yantai Mai Tel Biotechnology Co., Ltd.; the yeast (high-sugar-type high-activity dry yeast) is purchased from Angel Yeast Co., Ltd.

[0063] The technical solutions of the present application are described in detail below in conjunction with specific examples. In the following examples, the reagents, materials, and equipment used are commercially available unless otherwise specified, or are prepared by conventional methods or are commonly used in the industry.

[0064] Example 1: Establishment of a method for preparing low-GI malt dextrin

[0065] This example provides a method for preparing low-GI malt dextrin by double-enzyme synergy, and the specific steps are as follows:

[0066] (1) Disperse cassava starch in water to obtain a 10% (w / w, based on dry basis) starch milk, preheat at 60℃ for 10 min with stirring, adjust the pH to 7.0, and add 100 U / g of starch branching enzyme Ro-GBE to the starch milk, and gelatinize at 95℃ for 1 h;

[0067] (2) The gelatinization reaction product obtained in step (1) is cooled to 70°C and reacted for 12 h;

[0068] (3) The reaction product obtained in step (2) is cooled to 60°C, the pH value is adjusted to 5.5, 100 U / g of β-amylase is added, and the reaction is carried out at constant temperature for 6 h;

[0069] (4) The reaction product obtained in step (3) is directly cooled to 30°C, 1% of a yeast solution activated at 37°C is added, and the reaction is carried out at constant temperature for 48 h for co-culture and then the enzyme is inactivated by heating;

[0070] (5) Filtration: After cooling, the reaction solution is filtered through a filter membrane to remove yeast cells and impurities, and a product solution is obtained;

[0071] (6) Decolorization: The pH of the product solution obtained in step (5) is adjusted to 4.5, 1% of activated carbon is added at 45°C according to the mass ratio, and the solution is stirred for decolorization for 30 min to obtain a decolorized solution;

[0072] (7) Ion exchange decolorization: The ion exchange resin structure used is strong acid cation-weak base cation-strong acid cation exchange resin to remove metal salts and pigments in the decolorized solution obtained in step (6) at 45°C, and a solution containing low GI maltodextrin is obtained.

[0073] (8) The solution containing low GI maltodextrin obtained in step (7) is subjected to spray drying, the inlet air temperature of spray drying is 170°C, the outlet air temperature is 85°C, the material flow rate is 20 mL / min, and the product is obtained.

[0074] Comparative Example 1:

[0075] This comparative example provides a method for preparing low GI maltodextrin by double enzyme cooperation, without yeast fermentation treatment, and the specific steps are as follows:

[0076] (1) Cassava starch is dispersed in water to obtain a 10% (w / w, based on dry basis) starch milk, which is preheated at 60°C for 10 min with stirring, the pH is adjusted to 7.0, and 100 U / g of starch branching enzyme Ro-GBE is added to the starch milk, and gelatinization reaction is carried out at 95°C for 1 h;

[0077] (2) The gelatinization reaction product obtained in step (1) is cooled to 70°C and reacted for 12 h;

[0078] (3) The reaction product obtained in step (2) is cooled to 60°C, the pH value is adjusted to 5.5, 100 U / g of β-amylase is added, and the reaction is carried out at constant temperature for 48 h and then the enzyme is inactivated by heating;

[0079] (4) decolorization: the pH of the product solution obtained in step (3) is adjusted to 4.5, 1% activated carbon is added at 45°C, and the solution is stirred for decolorization for 30 min to obtain a decolorized solution;

[0080] (5) ion exchange decolorization: at 45°C, the ion exchange resin structure used is strong acid cation-weak base cation-strong acid cation exchange resin to remove metal salts and pigments in the decolorized solution obtained in step (4) to obtain a solution containing low GI maltodextrin;

[0081] (6) the solution containing low GI maltodextrin obtained in step (5) is subjected to alcohol precipitation treatment and vacuum drying to obtain a product.

[0082] Comparative Example 2:

[0083] This comparative example provides a method for preparing low GI maltodextrin, and the specific embodiment is similar to that of Comparative Example 1, except that no β-amylase is added in step (3).

[0084] Comparative Example 3:

[0085] This comparative example provides a method for preparing low GI maltodextrin, and the specific embodiment is similar to that of Comparative Example 1, except that:

[0086] In step (1), no starch branching enzyme Ro-GBE is added, and the temperature is directly raised to 95°C for gelatinization for 1 h.

[0087] Comparative Example 4:

[0088] This comparative example provides a method for preparing low GI maltodextrin by using a two-enzyme synergistic method, and the specific embodiment is similar to that of Comparative Example 1, except that:

[0089] Step (3) is modified as follows: the reaction product obtained in step (2) is cooled to 60°C, the pH value is adjusted to 5.5, 100 U / g of β-amylase is added, the temperature is raised to inactivate the enzyme after constant temperature reaction for 48 h, then the temperature is lowered to 30°C, 1% yeast solution activated at 37°C is added for culture for 24 h to remove small molecule sugars, then the solution is filtered through a filter membrane to remove yeast cells and impurities, and a clear solution is obtained;

[0090] Step (6) is modified as follows: the solution containing low GI maltodextrin obtained in step (5) is subjected to spray drying, the inlet air temperature for spray drying is 170°C, the outlet air temperature is 85°C, and the material flow rate is 20 mL / min to obtain a product.

[0091] The in vitro digestion performance of each modified product and untreated cassava starch is analyzed by an in vitro simulated digestion method, and the results are shown in Tables 1 and 2.

[0092] Table 1 Effect of two-enzyme synergistic modification

[0093] Table 2 Effect of yeast co-cultivation

[0094] The above results show that the modification method established in the present application can fully utilize the catalytic characteristics of the two amylases respectively, achieving the purpose of synergistic effect. First, the characteristics of Ro-GBE, which is resistant to high temperature and has hydrolysis and transglycosylation functions, can significantly reduce the viscosity of the gelatinized starch system and provide more branch sites for the action of β-amylase. Subsequently, the co-cultivation reaction using the sugar consumption characteristics of yeast can further enhance the modification efficiency, relieve product inhibition, and significantly reduce the fast digestibility of the product, which has obvious advantages in preparing low GI malt dextrin. After modification by the above process, the proportion of fast digestible components of the obtained product can be reduced to 65.09%, the proportion of slow digestible components can be increased to 12.40%, and the proportion of resistant components can be increased to 22.51%; compared with cassava starch, the proportion of fast digestible components is reduced by 32.98%, and the proportions of slow digestible and resistant components are increased by 3.79 times and 76.62 times, respectively. The reaction product is soluble in cold water, and the dissolution time is 3 min 21 s.

[0095] Example 2: Effect of gelatinization temperature on synergistic modification

[0096] The present embodiment provides a method for preparing low GI malt dextrin by double enzyme synergistic method, and the specific implementation manner is similar to that of example 1, and the specific steps include:

[0097] (1) Disperse cassava starch in water to obtain a 10% (w / w, based on dry basis) starch milk, preheat at 60℃ for 10 min under stirring, and adjust the pH to 7.0. Add 100 U / g of starch branching enzyme Ro-GBE to the starch milk, and gelatinize at 70℃, 75℃, 80℃, 85℃, 90℃, and 95℃ respectively for 1 h;

[0098] (2) Cool the gelatinized reaction product obtained in step (1) to 70℃ and react for 12 h;

[0099] (3) Cool the reaction product obtained in step (2) to 60℃, adjust the pH value to 5.5, add 100 U / g of β-amylase, and react at constant temperature for 6 h, then cool to 30℃, add 1% of yeast solution activated at 37℃ for co-cultivation for 48 h to remove small molecule sugars, then filter through a filter membrane to remove yeast cells and impurities, and sterilize to obtain a clear solution;

[0100] (4) Decolorization: adjust the pH of the product solution obtained in step (3) to 4.5, add 1% of activated carbon at a mass ratio under stirring at 45℃, and decolorize for 30 min to obtain a decolorized solution;

[0101] (5) Ion exchange: at 45℃, the ion exchange resin structure used is strong acid cation-weak base cation-strong acid cation exchange resin to remove metal salts and pigments in the decolorized solution obtained in step (4), to obtain a solution containing low GI maltodextrin;

[0102] (6) Spray drying the solution containing low GI maltodextrin obtained in step (5), the inlet air temperature of spray drying is 170℃, the outlet air temperature is 85℃, and the material flow rate is 20mL / min, to obtain the product.

[0103] The in vitro digestion performance of each modified product and untreated cassava starch was analyzed by an in vitro simulated digestion method, and the results are shown in Table 3.

[0104] Table 3 Influence of gelatinization temperature on synergistic modification effect

[0105] The results show that the synergistic modification method established by the application can further reduce the gelatinization temperature and energy consumption by taking advantage of the rapid hydrolysis and viscosity reduction of Ro-GBE. When the gelatinization temperature is 80℃, the in vitro digestion performance of the obtained product is further reduced, the fast digestion component ratio is reduced to 63.37%, the slow digestion component ratio is increased to 13.41%, and the resistant component ratio is increased to 23.22%. Compared with cassava starch, the fast digestion component ratio is reduced by 34.76%, and the slow digestion and resistant component ratios are increased by 4.18 times and 79.07 times, respectively; and the reaction product is soluble in cold water, and the dissolution time is 3min 12s.

[0106] Example 3: Influence of starch milk concentration on synergistic modification effect

[0107] The embodiment provides a method for preparing low GI maltodextrin by double-enzyme synergistic modification, and the specific implementation is based on the optimization of the gelatinization temperature to 80℃ in Example 2, and the specific steps include:

[0108] (1) Disperse cassava starch in water to obtain starch milk with a mass fraction of 10%, 15%, 20%, 25% and 30% (w / w, based on dry basis), respectively, preheat at 60℃ for 10min under stirring, and adjust the pH to 7.0; add 100U / g of starch branching enzyme Ro-GBE to the starch milk, and gelatinize at 80℃ for 1h;

[0109] (2) Cool the gelatinization reaction product obtained in step (1) to 70℃ and react for 12h;

[0110] (3) the reaction product obtained in step (2) is cooled to 60℃, the pH value is adjusted to 5.5, 100 U / g of β-amylase is added, and the reaction is carried out at constant temperature for 6 h, then the temperature is cooled to 30℃, 1% of the yeast solution activated at 37℃ is added, and the reaction is carried out at constant temperature for 48 h, then the yeast cells and impurities are removed by filtering through a filter membrane, and the enzyme is inactivated to obtain a clear solution;

[0111] (4) decolorization: the pH value of the product solution obtained in step (3) is adjusted to 4.5, 1% of activated carbon is added at 45℃ according to the mass ratio, and the solution is stirred for decolorization for 30 min to obtain a decolorized solution;

[0112] (5) ion exchange decolorization: the ion exchange resin structure used is strong acid cation-weak base cation-strong acid cation exchange resin, and the metal salt and pigment in the decolorized solution obtained in step (4) are removed at 45℃ to obtain a solution containing low-GI malt dextrin;

[0113] (6) the solution containing low-GI malt dextrin obtained in step (5) is subjected to spray drying, the inlet air temperature of the spray drying is 170℃, the outlet air temperature is 85℃, and the material flow rate is 20 mL / min, and different low-GI malt dextrin products are obtained.

[0114] The in-vitro digestion performance of each product and untreated cassava starch is analyzed by using the method of in-vitro simulated digestion, and the results are shown in Table 4.

[0115] Table 4 Influence of starch milk concentration on the synergistic modification effect

[0116] The results show that the synergistic modification method established in the application can process a higher concentration of starch milk (15% to 30%). When the concentration of starch milk is 15% (w / w, based on dry basis), the in-vitro digestion performance of the obtained product is further reduced, the proportion of fast-digestible component is reduced to 62.69%, the proportion of slow-digestible component is increased to 13.93%, and the proportion of resistant component is increased to 23.38%. Compared with cassava starch, the proportion of fast-digestible component is reduced by 35.45%, and the proportions of slow-digestible and resistant components are increased by 4.38 times and 79.62 times, respectively; compared with Example 2, the initial concentration of starch milk is increased by 1.5 times. Moreover, the reaction product is soluble in cold water, and the dissolution time is 3 min 05 s.

[0117] Example 4: Influence of Ro-GBE addition amount on the synergistic modification effect

[0118] This embodiment provides a method for preparing low-GI malt dextrin by double-enzyme synergistic method, and the specific implementation method is based on the optimization of the starch milk concentration to 15% (w / w, based on dry basis) in Example 3, and the specific steps include:

[0119] (1) cassava starch was dispersed in water to obtain 15% (w / w, based on dry basis) starch milk, preheated at 60°C for 10 min under stirring, and adjusted to pH 7.0, 100 U / g, 200 U / g, 300 U / g, 400 U / g, 500 U / g, 600 U / g of starch branching enzyme Ro-GBE was added to the starch milk, and pasting reaction was carried out at 80°C for 1 h;

[0120] (2) the pasting reaction product obtained in step (1) was cooled to 70°C and reacted for 12 h;

[0121] (3) the reaction product obtained in step (2) was cooled to 60°C, the pH value was adjusted to 5.5, 100 U / g of β-amylase was added, and constant temperature reaction was carried out for 6 h, then cooled to 30°C, 1% yeast solution activated at 37°C was added, and constant temperature co-culture reaction was carried out for 48 h, then filtered through a filter membrane to remove yeast cells and impurities, and enzyme was inactivated to obtain a clear solution;

[0122] (4) decolorization: the pH of the product solution obtained in step (3) was adjusted to 4.5, 1% activated carbon was added at 45°C according to the mass ratio, and stirring decolorization was carried out for 30 min to obtain a decolorized solution;

[0123] (5) ion exchange decolorization: at 45°C, the ion exchange resin structure used was strong acid cation-weak base cation-strong acid cation exchange resin to remove metal salts and pigments in the decolorized solution obtained in step (4) to obtain a solution containing low GI maltodextrin;

[0124] (6) the solution containing low GI maltodextrin obtained in step (5) was subjected to spray drying, the inlet air temperature of spray drying was 170°C, the outlet air temperature was 85°C, the material flow rate was 20 mL / min, and different low GI maltodextrin products were obtained, respectively.

[0125] The in vitro digestion performance of each product and untreated cassava starch was analyzed by in vitro simulated digestion method, and the results are shown in Table 5.

[0126] Table 5 Effect of Ro-GBE addition amount on synergistic modification

[0127] The results show that with the increase of the amount of Ro-GBE added, the in vitro digestion performance of the obtained product first decreases and then increases. When the amount of Ro-GBE added is 300 U / g, the in vitro digestion performance of the obtained product further decreases, the proportion of fast-digestible component decreases to 59.31%, and the proportions of slow-digestible and resistant components are 14.17% and 26.52%, respectively. Compared with cassava starch, the proportion of fast-digestible component decreases by 38.94%, and the proportions of slow-digestible and resistant components increase by 4.47 times and 90.45 times, respectively. Moreover, the reaction product is soluble in cold water, and the dissolution time is 2 min 39 s.

[0128] Example 5: Effect of Ro-GBE reaction time on the synergistic modification effect.

[0129] This embodiment provides a method for preparing low-GI malt dextrin by double-enzyme synergistic method. The specific implementation is based on the optimization of the amount of Ro-GBE added in Example 4, which is 300 U / g. The specific steps are as follows:

[0130] (1) Disperse cassava starch in water to obtain a 15% (w / w, based on dry basis) starch milk, preheat at 60°C for 10 min under stirring, and adjust the pH to 7.0. Add 300 U / g of Ro-GBE to the starch milk, and gelatinize at 80°C for 1 h;

[0131] (2) Cool the reaction product obtained in step (1) to 70°C, and react for 8 h, 12 h, 16 h, 20 h, and 24 h, respectively;

[0132] (3) Cool the reaction product obtained in step (2) to 60°C, adjust the pH to 5.5, add 100 U / g of β-amylase, and react at constant temperature for 6 h. Then, cool to 30°C, add 1% of yeast solution activated at 37°C, and co-culture at constant temperature for 48 h. Then, filter through a filter membrane to remove yeast cells and impurities, and inactivate the enzyme to obtain a clear solution;

[0133] (4) Decolorization: adjust the pH of the product solution obtained in step (3) to 4.5, add 1% of activated carbon at a mass ratio under 45°C, and stir for 30 min to obtain a decolorized solution;

[0134] (5) Ion exchange decolorization: use a strong acid cation-weak base cation-strong acid cation exchange resin to remove metal salts and pigments in the decolorized solution obtained in step (4) at 45°C, to obtain a solution containing low-GI malt dextrin;

[0135] (6) Spray dry the solution containing low-GI malt dextrin obtained in step (5), with an inlet air temperature of 170°C, an outlet air temperature of 85°C, and a material flow rate of 20 mL / min, to obtain different low-GI malt dextrin products.

[0136] The in vitro digestion performance of each product and untreated cassava starch was analyzed by in vitro simulated digestion assay, and the results are shown in Table 6.

[0137] Table 6 Influence of Ro-GBE reaction time on synergistic modification effect

[0138] The results show that as the Ro-GBE treatment time is prolonged, the in vitro digestion performance of the obtained product is further reduced. When the Ro-GBE treatment time reaches 16 h, the in vitro digestion performance of the obtained product is further reduced, the fast digestion component ratio is reduced to 57.82%, the slow digestion component ratio is increased to 15.33%, and the resistant component ratio is 26.85%. Compared with cassava starch, the fast digestion component ratio is reduced by 40.47%, and the slow digestion and resistant component ratios are increased by 4.92 times and 91.59 times, respectively. Moreover, the reaction product is soluble in cold water, and the dissolution time is 2 min 26 s.

[0139] Example 6: Influence of β-amylase addition amount on synergistic modification effect.

[0140] This embodiment provides a method for preparing low GI malt dextrin by double-enzyme synergistic method, and the specific implementation is based on the optimization of Ro-GBE reaction time to 16 h in Example 5, and the specific steps are as follows:

[0141] (1) Disperse cassava starch in water to obtain a 15% (w / w, dry basis) starch milk, preheat at 60°C for 10 min under stirring, and adjust the pH to 7.0. Add 300 U / g of Ro-GBE to the starch milk, and gelatinize at 80°C for 1 h;

[0142] (2) Cool the reaction product obtained in step (1) to 70°C and react for 16 h;

[0143] (3) Cool the reaction product obtained in step (2) to 60°C, and adjust the pH to 5.5. Add 100 U / g, 200 U / g, 300 U / g, 400 U / g, and 500 U / g of β-amylase, respectively, and react at constant temperature for 6 h. Then, cool to 30°C, add 1% of yeast solution activated at 37°C, and co-culture at constant temperature for 48 h. Then, filter through a filter membrane to remove yeast cells and impurities, and obtain a clear solution by enzyme inactivation;

[0144] (4) Decolorization: adjust the pH of the product solution obtained in step (3) to 4.5, add 1% of activated carbon at a mass ratio at 45°C, and stir for 30 min to obtain a decolorized solution;

[0145] (5) Ion exchange: at 45℃, the ion exchange resin structure used is strong acid cation-weak base cation-strong acid cation exchange resin to remove the metal salt and pigment in the decolorized solution obtained in step (4), to obtain a solution containing low GI maltodextrin;

[0146] (6) Spray drying the solution containing low GI maltodextrin obtained in step (5), the inlet air temperature of spray drying is 170℃, the outlet air temperature is 85℃, and the material flow rate is 20 mL / min, to obtain different low GI maltodextrin products.

[0147] The in vitro digestion performance of each product and untreated cassava starch was analyzed by in vitro simulated digestion method, and the results are shown in Table 7.

[0148] Table 7 Effect of β-amylase addition amount on synergistic modification

[0149] The results show that with the increase of β-amylase addition amount, the in vitro digestion performance of the obtained product first decreases and then increases. When the β-amylase addition amount is 300 U / g, the in vitro digestion performance of the obtained product further decreases, and the fast digestion component ratio decreases to 53.83%, and the slow digestion and resistant component ratios are 16.98% and 29.19%, respectively. Compared with cassava starch, the fast digestion component ratio decreases by 44.58%, and the slow digestion and resistant component ratios increase by 5.56 times and 99.66 times, respectively. And the reaction product is soluble in cold water, and the dissolution time is 2 min 13 s.

[0150] Example 7: Effect of β-amylase reaction time on synergistic modification

[0151] This embodiment provides a method for preparing low GI maltodextrin by double enzyme synergistic method, and the specific implementation is based on the optimization of β-amylase addition amount of 300 U / g in Example 6, and the specific steps are as follows:

[0152] (1) Disperse cassava starch in water to obtain a 15% (w / w, dry basis) starch milk, preheat at 60℃ for 10 min under stirring, and adjust the pH to 7.0, then add 300 U / g of Ro-GBE to the starch milk, and gelatinize at 80℃ for 1 h;

[0153] (2) Cool the reaction product obtained in step (1) to 70℃ and react for 16 h;

[0154] (3) The reaction product obtained in step (2) is cooled to 60°C, the pH value is adjusted to 5.5, 300 U / g of β-amylase is added, and after constant temperature reaction for 0 h, 3 h, 6 h, 9 h and 12 h, the temperature is then lowered to 30°C, 1% of the yeast solution activated at 37°C is added, and constant temperature co-culture reaction is carried out for 48 h, followed by filtration through a filter membrane to remove yeast cells and impurities, and enzyme inactivation to obtain a clear solution;

[0155] (4) Decolorization: the pH value of the product solution obtained in step (3) is adjusted to 4.5, 1% of activated carbon is added at a mass ratio of 45°C, and stirring decolorization is carried out for 30 min to obtain a decolorized solution;

[0156] (5) Ion exchange decolorization: at 45°C, the ion exchange resin structure used is strong acid cation-weak base cation-strong acid cation exchange resin to remove metal salts and pigments in the decolorized solution obtained in step (4) to obtain a solution containing low GI maltodextrin;

[0157] (6) The solution containing low GI maltodextrin obtained in step (5) is subjected to spray drying, the inlet air temperature of spray drying is 170°C, the outlet air temperature is 85°C, and the material flow rate is 20 mL / min, to obtain different low GI maltodextrin products, respectively.

[0158] The in vitro digestion performance of each product and untreated cassava starch was analyzed by in vitro simulated digestion method, and the results are shown in Table 8.

[0159] Table 8 Effect of β-amylase reaction time on synergistic modification

[0160] The results show that the longer the reaction time at 60°C, the more obvious the digestion of the product. It is speculated that the β-amylase has poor thermal stability and is partially inactivated. When the 60°C stage is removed and yeast co-culture is directly performed, the in vitro digestion performance of the obtained product is further reduced, the fast digestion component ratio is reduced to 51.77%, the slow digestion component ratio is increased to 18.53%, and the resistant component ratio is 29.70%. Compared with cassava starch, the fast digestion component ratio is reduced by 46.70%, and the slow digestion and resistant component ratios are increased by 6.15 times and 101.41 times, respectively. Moreover, the reaction product is soluble in cold water, and the dissolution time is 2 min 09 s.

[0161] Example 8: Effect of yeast co-culture temperature on synergistic modification

[0162] The specific implementation is to optimize and remove the β-amylase reaction step at 60°C in Example 7, and the specific steps are as follows:

[0163] (1) cassava starch was dispersed in water to obtain 15% (w / w, based on dry basis) starch milk, preheated at 60°C for 10 min with stirring, and adjusted to pH 7.0, 300 U / g of Ro-GBE was added to the starch milk, and gelatinized at 80°C for 1 h;

[0164] (2) the reaction product obtained in step (1) was cooled to 70°C and reacted for 16 h;

[0165] (3) the reaction product obtained in step (2) was directly cooled to 37°C or 30°C, and adjusted to pH 5.5, 300 U / g of β-amylase and 1% of yeast solution activated at 37°C were added, and reacted at constant temperature for 48 h, followed by filtration through a filter membrane to remove yeast cells and impurities, and enzyme inactivation to obtain a clear solution;

[0166] (4) decolorization: the pH of the product solution obtained in step (3) was adjusted to 4.5, 1% activated carbon was added at a mass ratio of 45°C with stirring for 30 min to obtain a decolorized solution;

[0167] (5) ion exchange decolorization: the ion exchange resin structure used was strong acid cation-weak base cation-strong acid cation exchange resin to remove metal salts and pigments in the decolorized solution obtained in step (4) at 45°C to obtain a solution containing low GI maltodextrin;

[0168] (6) the solution containing low GI maltodextrin obtained in step (5) was subjected to spray drying, the inlet air temperature of spray drying was 170°C, the outlet air temperature was 85°C, and the material flow rate was 20 mL / min, to obtain different low GI maltodextrin products, respectively.

[0169] The in vitro digestion performance of each product and untreated cassava starch was analyzed by in vitro simulated digestion method, and the results are shown in Table 9.

[0170] Table 9 Effect of yeast co-culture temperature on synergistic modification

[0171] The results show that directly adding yeast solution for co-reaction at the initial stage of β-amylase reaction can further reduce the in vitro digestion performance of the obtained product, and when co-cultured at 37°C, the proportion of fast digestible component can be reduced to 49.40%, and the proportions of slow digestible and resistant components are 18.93% and 31.67%, respectively. Compared with cassava starch, the proportion of fast digestible component is reduced by 49.14%, and the proportions of slow digestible and resistant components are increased by 6.31 times and 108.21 times, respectively. Moreover, the reaction product is soluble in cold water, and the dissolution time is 2 min 02 s.

[0172] Example 9: Effect of yeast co-culture time on synergistic modification

[0173] The specific implementation method is based on the optimized co-cultivation temperature of 37°C in Example 8, and the specific steps are as follows:

[0174] (1) Disperse cassava starch in water to obtain a 15% (w / w, on a dry basis) starch milk, stir and preheat at 60°C for 10 min, adjust the pH to 7.0, add 300 U / g of Ro-GBE to the starch milk, and gelatinize at 80°C for 1 h.

[0175] (2) Cool the reaction product obtained in step (1) to 70°C and react for 16 hours;

[0176] (3) The reaction product obtained in step (2) was directly cooled to 37°C and the pH was adjusted to 5.5. 300 U / g of β-amylase and 1% of yeast solution activated at 37°C were added and reacted at constant temperature for 12h, 24h, 36h, 48h and 60h respectively. Then, the solution was filtered through a filter membrane to remove yeast cells and impurities and to inactivate the enzyme to obtain a clear solution.

[0177] (4) Decolorization: Adjust the pH of the product solution obtained in step (3) to 4.5, add 1% activated carbon at 45℃ according to the mass ratio, and stir for 30 min to decolorize to obtain a decolorized solution;

[0178] (5) Ion decolorization: At 45°C, the ion exchange resin structure used is a strong acid cation-weak base cation-strong acid cation exchange resin to remove metal salts and pigments in the decolorized solution obtained in step (4) to obtain a solution containing low GI maltodextrin.

[0179] (6) The solution containing low-GI maltodextrin obtained in step (5) was spray-dried. The inlet air temperature of the spray drying was 170℃, the outlet air temperature was 85℃, and the material flow rate was 20mL / min, to obtain different low-GI maltodextrin products.

[0180] The in vitro digestibility of each product and untreated cassava starch was analyzed using an in vitro simulated digestibility assay. The results are shown in Table 10.

[0181] Table 10 Effect of yeast co-culture time on synergistic modification effect

[0182] The results show that the in vitro digestion performance of the obtained product will be further reduced as the co-culturing time is prolonged, and when the co-culturing time is prolonged to 60 h, the proportion of the rapidly digestible component can be reduced to 48.63%, and the proportions of the slowly digestible component and the resistant component are 19.07% and 32.30% respectively. Compared with cassava starch, the proportion of the rapidly digestible component is reduced by 49.93%, and the proportions of the slowly digestible component and the resistant component are increased by 6.36 times and 110.38 times respectively. Moreover, the reaction product is soluble in cold water, and the dissolution time is 2 min 02 s.

[0183] Example 10: Influence of secondary enzymatic hydrolysis on the synergistic modification effect

[0184] The specific implementation is based on the optimization of the co-culturing time of 60 h in Example 9, and the specific steps are as follows:

[0185] (1) Disperse cassava starch in water to obtain a 15% (w / w, based on dry basis) starch milk, preheat at 60°C for 10 min under stirring, and adjust the pH to 7.0. Add 300 U / g of Ro-GBE to the starch milk, and gelatinize at 80°C for 1 h;

[0186] (2) Cool the reaction product obtained in step (1) to 70°C and react for 16 h;

[0187] (3) Directly cool the reaction product obtained in step (2) to 37°C, adjust the pH to 5.5, add 300 U / g of β-amylase and 1% of the yeast solution activated at 37°C, and react at constant temperature for 60 h. Without enzyme inactivation, add 300 U / g of β-amylase and 1% of the yeast solution activated at 37°C again, and repeat the constant temperature reaction for 60 h. Then filter through a filter membrane to remove the yeast cells and impurities, and inactivate the enzyme to obtain a clear solution;

[0188] (4) Decolorization: adjust the pH of the product solution obtained in step (3) to 4.5, add 1% of activated carbon at a mass ratio at 45°C, and stir for 30 min to obtain a decolorized solution;

[0189] (5) Ion decolorization: at 45°C, use a strong acid cation-weak base cation-strong acid cation exchange resin to remove metal salts and pigments in the decolorized solution obtained in step (4) to obtain a solution containing low GI maltodextrin;

[0190] (6) Spray dry the solution containing low GI maltodextrin obtained in step (5), and the inlet air temperature of spray drying is 170°C, the outlet air temperature is 85°C, and the material flow rate is 20 mL / min, to obtain different low GI maltodextrin products.

[0191] The in vitro digestion performance of each product and untreated cassava starch was analyzed by in vitro simulated digestion method, and the results are shown in Table 11.

[0192] Table 11 Influence of secondary enzymatic hydrolysis on synergistic modification effect

[0193] The results show that although the primary enzymatic hydrolysis can make the substrate be fully hydrolyzed, it is not complete and a small amount of long-chain branches are not completely hydrolyzed, which may lead to an increase in digestibility. The introduction of the secondary enzymatic hydrolysis step can further completely hydrolyze the chain segments (the β-amylase hydrolysis rate tends to 0), reaching a state of extreme high branching, so that the digestive enzymes are difficult to hydrolyze, and the digestibility is improved. Finally, the proportion of fast-digestible components of the product obtained by secondary enzymatic hydrolysis can be reduced to 42.71%, and the proportions of slow-digestible and resistant components are 20.33% and 36.96%, respectively. Compared with cassava starch, the proportion of fast-digestible components is reduced by 56.03%, and the proportions of slow-digestible and resistant components are increased by 6.85 times and 126.45 times, respectively. Moreover, the reaction product is soluble in cold water, and the dissolution time is 1 min 51 s.

[0194] Example 11

[0195] After the solution of the commercially available maltodextrin (control) and the low-GI maltodextrin product with significantly reduced fast-digestible components obtained by secondary enzymatic hydrolysis in Example 10 was stored at 4°C for 30 days, the light transmittance of the solution was measured at 620 nm by a spectrophotometer, and the results are shown in FIG. 1. The commercially available maltodextrin quickly whitens in 3 days, while the sample always maintains a transmittance of more than 90%, which indicates that after the double-enzyme synergistic modification and secondary enzymatic hydrolysis, the stability of the sample solution is also greatly improved, which makes up for the shortcomings of natural starch being insoluble in cold water and the solution of commercially available maltodextrin being unstable and easy to retrograde, and realizes the simultaneous improvement of the slow-digestibility and stability of the product.

[0196] Example 12

[0197] The relative molecular weight of the original cassava starch and the product obtained by secondary enzymatic hydrolysis in Example 10, the product obtained in Comparative Example 2, and the product obtained in Comparative Example 3 was measured and analyzed, and the results are shown in Table 12. It can be seen from the results that since the β-amylase belongs to an exoenzyme, its degradation efficiency on the original starch is low, resulting in a small change in molecular weight, so that the product still retains the high viscosity property of the original starch during the reaction. The Ro-GBE has the advantage of rapidly hydrolyzing and reducing viscosity, because it needs to first hydrolyze a part of the chain segments and then reconnect them to the outer chain of the starch in the form of branches. Therefore, the first addition of Ro-GBE can further improve the hydrolysis efficiency of the β-amylase, so that the product is further hydrolyzed into maltodextrin with a small molecular weight, and the stability is further improved.

[0198] Table 12 Relative molecular weight of native starch and modified products

[0199] Example 13

[0200] The modification process (secondary enzymatic hydrolysis) of the above Example 10 was applied to different kinds of starches, and the in vitro simulated digestion performance was determined. The results are shown in Table 13. From the results in the table, it can be seen that this process is also applicable to different kinds of starches, and has good application potential.

[0201] Table 13 Applicability of the above modification process to different kinds of starches

[0202] Obviously, the above examples are merely illustrative examples for the sake of clarity, and are not intended to limit the embodiments. Based on the above description, other different forms of changes or variations can also be made by those of ordinary skill in the art. It is not necessary or possible to exhaust all embodiments. The obvious changes or variations derived therefrom are still within the protection scope of the present application.

Claims

1. A method of producing low GI maltodextrin in a two-enzyme synergy, characterized by, The method comprises the following steps: (1) dispersing starch granules in water to obtain a starch milk; adding starch branching enzyme Ro-GBE to the obtained starch milk, heating to perform a gelatinization reaction, and then continuing to perform a constant temperature reaction after cooling, to obtain reaction liquid 1; (2) after cooling the reaction liquid 1 obtained in step (1), adding β-amylase and yeast to perform a reaction, to obtain reaction liquid 2; (3) drying the reaction liquid 2 obtained in step (2) to obtain the low GI maltodextrin.

2. The method of claim 1, wherein, In step (1), the starch is selected from one or more of the following: cassava starch, ordinary corn starch, waxy corn starch, potato starch, rice starch, and wheat starch.

3. The method of claim 1, wherein, In step (1), the concentration of the starch milk is 10%-30% (w / w); and the pH value of the starch milk is 6.0-7.

5.

4. The method of claim 1, wherein, In step (1), the starch branching enzyme Ro-GBE is derived from Rhodothermus obamensis STB05, and the nucleotide sequence is shown in SEQ ID NO.

1.

5. The method of claim 1, wherein, In step (1), the addition amount of the starch branching enzyme Ro-GBE is 100 U / g-1000 U / g of dry starch.

6. The method of claim 1, wherein, In step (1), the temperature of the gelatinization reaction is 70°C-95°C; and the time of the gelatinization reaction is 0 h-5 h.

7. The method of claim 1, wherein, In step (1), the temperature of the constant temperature reaction is 60°C-80°C; and the time of the constant temperature reaction is 8 h-48 h.

8. The method of claim 1, wherein, In step (2), the temperature after cooling is 30°C-60°C.

9. The method of claim 1, wherein, In step (2), the addition amount of the β-amylase is 100 U / g-1000 U / g of dry starch.

10. The method of claim 1, wherein, In step (2), the addition amount of the yeast is 0.5%-5%.

11. The method of claim 1, wherein, In step (2), the temperature of the reaction is 30°C-60°C; and the time of the reaction is 6 h-72 h.

12. The method of claim 1, wherein, In step (2), after the reaction, the reaction is further performed again by adding β-amylase and yeast.

13. The method of claim 12, wherein, The addition amount of the β-amylase is 100 U / g-1000 U / g of dry starch.

14. The method of claim 12, wherein, The addition amount of the yeast is 0.5%-5%.

15. The method of claim 12, wherein, The temperature of the secondary reaction is 30°C-60°C; and the time of the secondary reaction is 6 h-72 h.

16. The method of claim 1, wherein, In step (2), after the reaction, the reaction is further performed again by adding β-amylase and yeast.

17. The method of claim 16, wherein, The addition amount of the β-amylase is 100 U / g-1000 U / g of dry starch. The addition amount of the yeast is 0.5%-5%.

18. The method of claim 1, wherein, The temperature of the secondary reaction is 30°C-60°C; and the time of the secondary reaction is 6 h-72 h. In step (2), after the reaction, the reaction is further performed again by adding β-amylase and yeast. The addition amount of the β-amylase is 100 U / g-1000 U / g of dry starch. The addition amount of the yeast is 0.5%-5%. The temperature of the secondary reaction is 30°C-60°C; and the time of the secondary reaction is 6 h-72 h. In step (2), after the reaction, the reaction is further performed again by adding β-amylase and yeast. The addition amount of the β-amylase is 100 U / g-1000 U / g of dry starch. The addition amount of the yeast is 0.5%-5%. The temperature of the secondary reaction is 30°C-60°C; and the time of the secondary reaction is 6 h-72 h. In step (2), after the reaction, the reaction is further performed again by adding β-amylase and yeast. The addition amount of the β-amylase is 100 U / g-1000 U / g of dry starch. The addition amount of the yeast is 0.5%-5%. The temperature of the secondary reaction is 30°C-60°C; and the time of the secondary reaction is 6 h-72 h. In step (2), after the reaction, the reaction is further performed again by adding β-amylase and yeast. The addition amount of the β-amylase is 100 U / g-1000 U / g of dry starch. The addition amount of the yeast is 0.5%-5%. The temperature of the secondary reaction is 30°C-60°C; and the time of the secondary reaction is 6 h-72 h. In step (2), after the reaction, the reaction is further performed again by adding β-amylase and yeast. The addition amount of the β-amylase is 100 U / g-1000 U / g of dry starch. The addition amount of the yeast is 0.5%-5%. The temperature of the secondary reaction is 30°C-60°C; and the time of the secondary reaction is 6 h-72 h. In step (2), after the reaction, the reaction is further performed again by adding β-amylase and yeast. The addition amount of the β-amylase is 100 U / g-1000 U / g of dry starch. The addition amount of the yeast is 0.5%-5%. The temperature of the secondary reaction is 30°C-60°C; and the time of the secondary reaction is 6 h-72 h. In step (2), after the reaction, the reaction is further performed again by adding β-amylase and yeast. The addition amount of the β-amylase is 100 U / g-1000 U / g of dry starch. The addition amount of the yeast is 0.5%-5%. The temperature of the secondary reaction is 30°C-60°C; and the time of the secondary reaction is 6 h-72 h. In step (2), after the reaction, the reaction is further performed again by adding β-amylase and yeast. The addition amount of the β-amylase is 100 U / g-1000 U / g of dry starch. The addition amount of the yeast is 0.5%-5%. The temperature of the secondary reaction is 30°C-60°C; and the time of the secondary reaction is 6 h-72 h. In step (2), after the reaction, the reaction is further performed again by adding β-amylase and yeast. The addition amount of the β-amylase is 100 U / g-1000 U / g of dry starch. The addition amount of the yeast is 0.5%-5%. The temperature of the secondary reaction is 30°C-60°C; and the time of the secondary reaction is 6 h-72 h. In step (2), after the reaction, the reaction is further performed again by adding β-amylase and yeast. The addition amount of the β-amylase is 100 U / g-1000 U / g of dry starch. The addition amount of the yeast is 0.5%-5%. The temperature of the secondary reaction is 30°C-60°C; and the time of the secondary reaction is 6 h-72 h. In step (2), after the reaction, the reaction is further performed again by adding β-amylase and yeast. The addition amount of the β-amylase is 100 U / g-1000 U / g of dry starch. The addition amount of the yeast is 0.5%-5%. The temperature of the secondary reaction is 30°C-60°C; and the time of the secondary reaction is 6 h-72 h. In step (2), after the reaction, the reaction is further performed again by adding β-amylase and yeast. The addition amount of the β-amylase is 100 U / g-1000 U / g of dry starch. The addition amount of the yeast is 0.5%-5%. The temperature of the secondary reaction is 30°C-60°C; and the time of the secondary reaction is 6 h-72 h. In step (2), after the reaction, the reaction is further performed again by adding β-amylase and yeast. The addition amount of the β-amylase is 100 U / g-1000 U / g of dry starch. The addition amount of the yeast is 0.5%-5%. The temperature of the secondary reaction is 30°C-60°C; and the time of the secondary reaction is 6 h-72 h. In step (2), after the reaction, the reaction is further performed again by adding β-amylase and yeast. The addition amount of the β-amylase is 100 U / g-1000 U / g of dry starch. The addition amount of the yeast is 0.5%-5%. The temperature of the secondary reaction is 30°C-60°C; and the time of the secondary reaction is 6 h-72 h. In step (2), after the reaction, the reaction is further performed again by adding β-amylase and yeast. The addition amount of the β-amylase is 100 U / g-1000 U / g of dry starch. The addition amount of the yeast is 0.5%-5%. The temperature of the secondary reaction is 30°C-60°C; and the time of the secondary reaction is 6 h-72 h. In step (2), after the reaction, the reaction is further performed again by adding β-amylase and yeast. The addition amount of the β-amylase is 100 U / g-1000 U / g of dry starch. The addition amount of the yeast is 0.5%-5%. The temperature of the secondary reaction is 30°C

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