Method for detecting soluble dietary fiber in resistant dextrin

Abstract

The application belongs to the technical field of food detection, and provides a detection method of soluble dietary fiber in resistant dextrin. The method adopts amylodextrinase to perform enzymatic digestion on the resistant dextrin, adds water to prepare a test solution; glucose is used as a standard, high performance liquid chromatography is used for detection, and the content of the soluble dietary fiber in the resistant dextrin is obtained by an external standard method. The detection method is simpler than the existing standard method, greatly reduces the error sources, can guarantee the accuracy and precision of the detection results, shortens the detection time, saves manpower and economic cost, and can meet the detection needs of inspection supervision departments and enterprises.

Description

Technical Field

[0001] This invention belongs to the field of food testing technology and relates to a method for detecting soluble dietary fiber in resistant dextrin. Background Technology

[0002] Resistant dextrin is made from starch. It is a low-calorie glucan produced by industrially extracting and refining the indigestible components of roasted dextrin. It belongs to the category of low-molecular-weight soluble dietary fiber. Its production process involves the hydrolysis and repolymerization of starch, forming glycosidic bonds that cannot be broken by enzymes in the digestive tract, thus converting starch into soluble dietary fiber. Soluble dietary fiber stimulates intestinal peristalsis, facilitating bowel movements and preventing constipation, rectal cancer, hemorrhoids, and varicose veins in the lower extremities. It can also prevent cardiovascular diseases such as arteriosclerosis and coronary heart disease, and prevent gallstone formation. It can create a feeling of fullness, which is beneficial for obese patients and can be used as a weight-loss food. Furthermore, it can improve glucose tolerance, regulate blood sugar levels in diabetics, and can be used as a food for diabetics. It can also improve gut microbiota and prevent colon cancer and appendicitis.

[0003] Currently, the main detection methods for soluble dietary fiber in the industry are: AOAC Official Method 2009.01 Total Dietary Fiber in Food (AOAC Official Method 2009.01 Total Dietary Fiber in Food by Enzyme Weight - Liquid Chromatography) and GB... The national food safety standard GB / T 22224-2008, "Determination of Dietary Fiber in Food" (5009.88-2014) and the second method of "Determination of Dietary Fiber in Food - Enzyme Gravimetric Method and Enzyme Gravimetric Method-Liquid Chromatography," describe the basic process for detecting soluble dietary fiber as follows: weighing → amylase hydrolysis → protease hydrolysis → amylase hydrolysis → filtration → alcohol precipitation → filtration. The residue is then subjected to constant weight, ashing, and protein determination to obtain high molecular weight soluble dietary fiber precipitated in ethanol. The filtrate is then subjected to internal standard addition, concentration, desalting, and chromatographic analysis to obtain non-precipitated soluble dietary fiber. The content of soluble dietary fiber is obtained by adding the two portions of soluble dietary fiber.

[0004] This detection method does not include low molecular weight (DP = 3-12) soluble dietary fiber, such as fructooligosaccharides, galactooligosaccharides, polydextrose, resistant dextrin, and resistant starch. This type of method involves numerous and complex steps, is time-consuming (requiring 2-3 days), requires testing multiple items (residue, protein, ash, etc.), lacks strict quantitative procedures, and is subject to many uncertainties affecting the results. Furthermore, the detection of soluble dietary fiber in high-content (purity > 90%) resistant dextrin is prone to bias. The method has significant errors, stemming from various sources including those introduced by the drying and constant weight determination of the precipitate, errors introduced by ash content determination, errors introduced by protein determination, errors introduced by the blank method, errors introduced by differences in processing between parallel samples, errors in the conversion coefficient of the internal standard, the influence of impurities, the influence of integration, and errors caused by the instrument itself. These numerous and complex sources of error make it unsuitable for the quality control of high-purity soluble dietary fiber, as it presents difficulties in reproducing the results. Furthermore, the method involves numerous operational steps, a large number of detection items, and requires a lot of detection equipment, making it time-consuming and unsuitable for the detection of large batches of samples.

[0005] Chinese invention patent application CN106092815A discloses a method for determining total dietary fiber in food. The method first involves enzymatically hydrolyzing the food material according to step 6.2 of the national standard GB 5009.88-2014; then precipitating the precipitate in ethanol; filtering and drying the precipitate; calculating the mass of the residue; determining the protein and ash content in the residue; and finally calculating the total dietary fiber content according to the formula in GB 5009.88. While this method simplifies the pretreatment steps for total dietary fiber in food and can improve detection efficiency to some extent, it requires duplicate samples and still relies on the ash and protein content in the residue for total dietary fiber calculation, thus introducing errors during the ash and protein determination process.

[0006] Therefore, given the problems existing in the national standard method during the testing process, there is an urgent need to improve the testing method so as to ensure the accuracy and precision of the test results, shorten the testing time, and save manpower and economic costs, thereby meeting the urgent needs of inspection and supervision departments and enterprises. Summary of the Invention

[0007] This invention addresses the problems of complex sample pretreatment, multiple detection methods involved in the detection process, wide sources of error, and low detection efficiency in existing technologies. It provides a method for detecting soluble dietary fiber in resistant dextrin, eliminating the need for alcohol precipitation and separate testing of alcohol-precipitated and alcohol-soluble dietary fiber. The test solution is prepared by enzymatic hydrolysis with a single amyloglucosidase, and glucose is used as a standard. The result is directly calculated by high-performance liquid chromatography using the external standard method. This method is simple to operate, highly efficient, and provides accurate detection results.

[0008] The technical solution of the present invention is as follows:

[0009] The resistant dextrin was enzymatically digested using amylase, and the solution was diluted with water to obtain the test solution. Using glucose as a standard, the soluble dietary fiber content in the resistant dextrin was determined by high performance liquid chromatography and the external standard method.

[0010] Furthermore, the specific steps of the detection method are as follows:

[0011] (1) Preparation of standard solution: Add the standard to water and dissolve it to obtain the solution;

[0012] (2) Preparation of blank solution: Add amyloglucosidase to Tris buffer, digest with enzymes, and then filter to obtain the solution;

[0013] (3) Preparation of test solution: Add resistant dextrin and amyloglucosidase to Tris buffer, digest with enzymes, add water to make up to volume, and filter to obtain the solution;

[0014] (4) Inject the standard solution, blank solution and test solution into the high performance liquid chromatograph for testing;

[0015] (5) The soluble dietary fiber content in the resistant dextrin of the test sample was calculated by external standard method using the blank subtraction method.

[0016] This invention utilizes Tris buffer to enzymatically hydrolyze resistant dextrin, a system with a pH environment suitable for amyloglucosidase, eliminating the need for pH adjustment, simplifying the operation, and reducing sample loss during pH adjustment. Furthermore, in the preparation of the test solution, water is directly added to the solution after enzymatic hydrolysis, improving upon the loss of soluble dietary fiber caused by alcohol precipitation in existing technologies and reducing result errors.

[0017] Furthermore, the standard is D-glucose.

[0018] Furthermore, the concentration of the standard solution is 3-8 g / L; preferably 5 g / L.

[0019] To ensure the accuracy of the external standard method calculation results, the content of soluble dietary fiber in antagonistic dextrin was detected by subtracting the blank. The blank subtraction method uses a blank solvent, that is, a blank solution prepared under the same conditions as the test sample preparation process, the same amyloglucosidase and Tris buffer, at the same concentration and temperature, and for the same amount of time as the blank solution, in order to subtract the influence of the blank background peak on the integral area.

[0020] Furthermore, in steps (2) and (3), the amyloglucosidase accounts for 0.10-0.50% of the volume of the Tris buffer; preferably 0.15%.

[0021] Furthermore, in step (3), the concentration of the resistant dextrin in Tris buffer containing amyloglucosidase is 3-8 g / L.

[0022] Furthermore, in step (3), water is added to adjust the volume to a concentration of resistant dextrin of 5-10 g / L; preferably 5 g / L.

[0023] Furthermore, in steps (1)-(3), the filtration uses an aqueous phase filter membrane.

[0024] Furthermore, the pore size of the aqueous filter membrane is 0.45-0.50 μm; preferably 0.45 μm.

[0025] Furthermore, in steps (2) and (3), during the preparation of the blank solution and the test solution, the enzymatic hydrolysis temperature is 55-60℃; preferably 58-60℃, and the enzymatic hydrolysis time is 0.5-1h; preferably 1h.

[0026] Furthermore, in step (5), the calculation process for the soluble dietary fiber content is as follows: first, subtract the area of ​​the blank solution from the peak area of ​​the glucose polymer in the test sample solution to obtain the peak area of ​​the soluble dietary fiber, and then compare it with the peak area of ​​the glucose standard solution to calculate the content of soluble dietary fiber in the test sample.

[0027] Furthermore, the glucose polymer peak area is a glucose polymer peak area with DP≥3.

[0028] Furthermore, the high-performance liquid chromatography conditions are as follows:

[0029] Chromatographic column: gel guard column and two gel chromatography columns in series; column temperature: 70℃;

[0030] Detector: Differential refractive index detector, detection temperature 50℃;

[0031] Mobile phase: Primary water; Flow rate: 0.5 mL / min;

[0032] Injection volume: 50 μL; Data acquisition time: 60 min.

[0033] Furthermore, the guard column has dimensions of 6.0 mm × 40 mm and a diameter of 6 μm; the chromatographic column has dimensions of 7.8 mm × 300 mm and a diameter of 6 μm.

[0034] Compared with the prior art, the present invention has the following beneficial effects:

[0035] 1. Compared with the national standard method for determining soluble dietary fiber content, this invention provides a new approach to testing soluble dietary fiber content using HPLC external standard method with glucose as standard. This method is simple to operate and yields accurate results.

[0036] 2. The test solution of the present invention enzymatically hydrolyzes the resistant dextrin in Tris buffer with amylase. The pH of this system is suitable for amylase, so there is no need to adjust the pH of the solution. The operation is simple and avoids sample loss during the operation.

[0037] 3. The detection method uses water to make up to volume, which is simple to operate and does not require alcohol precipitation. This avoids sample loss caused by operation during alcohol precipitation, as well as errors introduced during alcohol precipitation of soluble dietary fiber ash and protein testing, resulting in higher accuracy.

[0038] 4. This method uses blank elimination to eliminate the interference of salt on dietary fiber detection, eliminating the desalting step in the original method and greatly reducing the sample processing time; at the same time, it avoids the error caused by sample loss during the desalting process, further improving the accuracy.

[0039] 5. Using glucose to directly quantify dietary fiber eliminates the original method of calibrating an internal standard with glucose and then calibrating dietary fiber with the internal standard. Furthermore, the glucose chromatographic peak is free of interfering peaks, has a stable baseline, and provides very accurate integration, significantly reducing the difficulty of operation. At the same time, it avoids potential interference from the sample itself to the internal standard and inaccurate chromatographic peak integration caused by fluctuations in chromatographic conditions, resulting in more accurate test results.

[0040] 6. The soluble dietary fiber detection method of this invention meets the requirements of GB / T 27404-2008 "Laboratory Quality Control Standard", is scientific and effective, and can achieve the purpose of quality control of the soluble dietary fiber content in soluble dietary fiber raw materials. Attached Figure Description

[0041] Figure 1 This is a flowchart of the method for detecting soluble dietary fiber in resistant fibers according to the present invention.

[0042] Figure 2 This is a chromatogram of the standard (D-glucose) solution from Example 1 of the present invention;

[0043] Figure 3 This is the chromatogram of the blank solution in Example 1 of the present invention;

[0044] Figure 4 This is the chromatogram of the test solution in Example 1 of the present invention;

[0045] Figure 5The flowchart is for the comparative method (GB / T 22224-2008) for the detection of soluble dietary fiber.

[0046] Figure 6 This is a standard working curve for D-glucose. Detailed Implementation

[0047] The following non-limiting embodiments are intended to enable those skilled in the art to gain a more comprehensive understanding of the present invention, but do not limit the invention in any way. The following content is merely an exemplary description of the scope of protection of the present invention, and those skilled in the art can make various changes and modifications to the invention based on the disclosed content, which should also fall within the scope of protection of the present invention.

[0048] Unless otherwise specified, all reagents used were of analytical grade, and the water was grade III water;

[0049] Amylase: SIGMA, CAS No.: 9032-08-0, A9913-10mL;

[0050] Tris buffer: Dissolve 6.1 g of tris(hydroxymethyl)aminomethane (Tris) in 1000 mL of water, and adjust the pH to (pH 4.5 ± 0.2) with 1 mol / L hydrochloric acid.

[0051] D-Glucose: Aladdin, batch number: H1921084, superior grade, purity ≥99.5%, constant weight treatment in a 105℃ oven before use, and finally calculated as 100% purity;

[0052] The test sample was soluble dietary fiber (resistant dextrin), number: TW22092692-001.

[0053] The following is combined with Figure 1 The method for detecting soluble dietary fiber in resistant dextrin, as shown, provides a detailed description of the technical solution of this invention.

[0054] Example 1:

[0055] 1.1 Preparation of standard solution: Accurately weigh 0.25 g of D-glucose to a constant weight into a 50 mL volumetric flask, dissolve in water and dilute to the mark, mix well, and filter through a 0.45 μm aqueous phase filter membrane to obtain the standard solution.

[0056] 1.2 Preparation of test solution: Accurately weigh 0.25 g of test sample into a 50 mL volumetric flask, accurately add 20.0 mL of Tris buffer containing amylase (add 0.15 mL of amylase per 100 mL Tris buffer), mix well to dissolve the sample, and enzymatically digest in a water bath at 58-60℃ for 1 hour, gently mixing 3-4 times during the process. Cool to room temperature, dilute to the mark with water, and pass through a 0.45 μm aqueous membrane to obtain the solution (sample 1, sample 2, and sample 3 were prepared by taking 3 different batches of samples and preparing them according to this method).

[0057] 1.3 Blank solution: Accurately add 20.0 mL of Tris buffer containing amylase (0.15 mL of amylase per 100 mL Tris buffer) to a 50 mL volumetric flask, and incubate in a water bath at 58-60℃ for 1 hour, gently mixing 3-4 times during the process. Cool to room temperature, dilute to the mark with water, and pass through a 0.45 μm aqueous membrane to obtain the blank solution.

[0058] 1.4 Determination Method: 50 μL of standard solution, test solution, and blank solution were injected into the high-performance liquid chromatograph for analysis. The results are shown in the figure. Figure 2-4 ;

[0059] The chromatographic conditions are as follows:

[0060] Chromatographic columns: gel guard column (6.0 mm × 40 mm, 6 μm); two gel chromatography columns in series (7.8 mm × 300 mm, 6 μm);

[0061] Column temperature: 70℃;

[0062] Detector: Differential refractive index detector, detection temperature 50℃;

[0063] Mobile phase: Primary water; Flow rate: 0.5 mL / min;

[0064] Injection volume: 50 μL;

[0065] Data acquisition time: 60 minutes.

[0066] The peak area of ​​soluble dietary fiber is obtained by subtracting the area of ​​the blank solution from the peak area of ​​glucose polymers with DP≥3 in the test sample solution. This peak area is then compared with the peak area of ​​the glucose standard solution to calculate the content of soluble dietary fiber in the test sample. For non-enzymatic samples, it is not necessary to subtract the area of ​​the blank solution. The soluble dietary fiber content in the test sample is calculated according to the following formula:

[0067]

[0068] In the formula:

[0069] X—Soluble dietary fiber content in the test sample, %;

[0070] A 总 —Peak area of ​​total dietary fiber in the test sample;

[0071] A 空 —Peak area of ​​dietary fiber in the blank method;

[0072] C 标 —The concentration of the standard solution, in mg / mL;

[0073] V—Dilution volume of the test solution, mL;

[0074] A 标 —Peak area of ​​the standard solution;

[0075] m—sample size of the test sample, in grams.

[0076] 1.6 Refer to step 1.2 (omit the enzymatic hydrolysis step) to test its soluble dietary fiber content and glucose content.

[0077] The results are shown in Table 1;

[0078] Table 1 Comparison of soluble dietary fiber and glucose content results

[0079]

[0080] According to the results in Table 1, the glucose content in the solution was significantly higher than that without enzymatic hydrolysis. This indicates that the use of amyloglucosidase for enzymatic hydrolysis can significantly eliminate the influence of insoluble dietary substances such as dextrins and effectively remove the influence of glucosidic chains on the content of soluble dietary fiber, resulting in good enzymatic hydrolysis effect.

[0081] Example 2

[0082] According to the method described in Method II of GB / T 22224-2008 "Determination of Dietary Fiber in Food - Enzyme Gravimetric Method and Enzyme Gravimetric Method - Liquid Chromatography" (method flowchart shown below) Figure 5 (As shown) The content of soluble dietary fiber in sample 2 of Example 1 of this application was tested; the results are shown in Table 2.

[0083] Table 2. Results of soluble dietary fiber content obtained by different methods.

[0084]

[0085] As shown in Table 2, although the test results of soluble and insoluble dietary fiber precipitated in ethanol differed significantly under different concentrations of ethanol precipitation, the total amount of soluble dietary fiber in both groups was very similar, indicating a high correlation between soluble and insoluble dietary fiber precipitated in ethanol. Compared with the detection results of Example 1 of this invention, the test results of the two methods are close, indicating that chromatography can be used directly to simultaneously detect soluble and insoluble dietary fiber precipitated in ethanol. Therefore, this invention eliminates the numerous complex steps of dietary fiber precipitation, drying, ashing, and desalting in the comparative method (see...). Figure 5 This new method avoids many influencing factors found in the original method, such as the impact of the blank method on the test results, the effect of ethanol concentration on fiber precipitation, and the loss of dietary fiber during filtration. Furthermore, the original method, when detecting non-precipitable soluble dietary fiber, could not perform a rigorous quantitative analysis process due to salt interference, requiring the use of internal standard methods and desalting for accurate quantification, increasing the operational complexity and difficulty of the method. The original method involved multiple detection methods and multi-step calculations, such as residue drying to constant weight and calculation, ash content determination and calculation, protein determination and calculation, and liquid chromatography determination and calculation, involving multiple testing equipment and personnel, with a testing cycle of up to 3 days, resulting in high testing costs and low efficiency.

[0086] The detection method of this invention is simple, fast, highly accurate, and efficient, with a detection cycle of one day. It involves only one person and one detection method, eliminating a large number of operational procedures (see...). Figure 1 This method saves a lot of manpower and material costs and is more suitable for testing large batches of samples compared to the original method.

[0087] Example 3

[0088] Five batches of resistant dextrin samples were selected and divided into two groups, with two parallel samples in each group. The soluble dietary fiber content of the samples was tested according to Example 1 of this invention and the comparative method, and the relative error between the two parallel samples was calculated. The results are shown in Tables 3 and 4.

[0089] Table 3. Results of soluble dietary fiber content and relative error detected by comparative method.

[0090]

[0091] Table 4 shows the results of detecting soluble dietary fiber content and relative error according to the method in Example 1 of this invention.

[0092]

[0093]

[0094] As shown in Table 3, the relative error range of soluble dietary fiber precipitated in ethanol is between 0.4% and 14.1%, with most relative errors around 10%. The relative error range of non-precipitable soluble dietary fiber is between 0.3% and 8.7%. As shown in Table 4, the relative error range of the patented method for detecting soluble dietary fiber is between 0.2% and 1.2%. The relative error of the test results is significantly better than that of existing methods, indicating that the patented method has better detection precision.

[0095] The method of this invention directly uses glucose to quantify dietary fiber in samples, and the glucose chromatographic peak has a stable baseline, accurate integration, and is completely unaffected by the sample matrix (see...). Figure 2 This method solves the shortcomings of the internal standard method; based on strict quantitative operation, the effect of salt on dietary fiber can be completely eliminated by the blank removal method, thus eliminating the desalting operation in the original method and greatly reducing the difficulty of operation.

[0096] Test Example: Method Validation for the Determination of Soluble Dietary Fiber Content in Resistant Dextrin

[0097] (1) Specificity test:

[0098] 1.1 Test Methods:

[0099] Three blank solutions were prepared independently, and the peak area of ​​dietary fiber in the blank solutions was recorded and its RSD was examined.

[0100] 1.2 Test results (see Table 3):

[0101] Table 5 Peak area of ​​dietary fiber in blank solution

[0102] 1 2 3 average RSD, % 1258933 1263258 1261237 1261143 0.18

[0103] 1.3 Experimental Conclusions:

[0104] The RSD of the peak area of ​​dietary fiber in the three independent blank solutions was 0.18%, indicating that the dietary fiber in the blank solutions has very good precision and will not adversely interfere with the detection of soluble dietary fiber in the samples, indicating that the method has good specificity.

[0105] (2) Linear range confirmation:

[0106] 2.1 Test Methods:

[0107] Accurately weigh 0.02611 g, 0.10353 g, 0.25207 g, 0.41488 g, and 0.60186 g of D-glucose to constant weight into 50 mL volumetric flasks, dissolve in water and dilute to the mark, mix well, and pass through a 0.45 μm aqueous membrane to obtain a series of standard glucose solutions.

[0108] 2.2 Standard Working Curve Diagram:

[0109] The peak areas of the corresponding chromatograms for the above standard solutions are shown in Table 6;

[0110] Table 6 Results of the glucose standard curve

[0111]

[0112] A standard working curve was plotted with glucose concentration (mg / mL) on the x-axis and peak area on the y-axis, as shown below. Figure 6 As shown.

[0113] 2.3 Conclusions of the Linearity Test

[0114] Linearity evaluation: The correlation coefficient R of the glucose standard curve was 0.99999. Therefore, the method for determining soluble dietary fiber showed good linearity between concentrations of 0.5222 mg / mL and 12.0372 mg / mL, which meets the requirements of GB / T27404-2008 "Laboratory Quality Control Standard" [GB / T27404-2008 requires a correlation coefficient R≥0.99].

[0115] (3) Limit of detection and limit of quantitation:

[0116] The limits of detection (DL) and quantitation (QL) of the analytical method are calculated using the signal-to-noise ratio (S / N); DL is defined as the concentration to be analyzed when S / N = 3, and QL is defined as the concentration to be analyzed when S / N = 10.

[0117] 3.1 Limit of Detection

[0118] When the signal-to-noise ratio (S / N) is 3, the limit of detection for glucose is 0.50 μg / mL; when the sample size is 0.25 g and the volume is adjusted to 50 mL, the limit of detection for soluble dietary fiber is 0.5 × 50 × 100 / 0.25 / 1000 = 10 mg / 100 g.

[0119] 3.2 Limit of Quantification

[0120] When the signal-to-noise ratio (S / N) is 10, the limit of quantification for glucose is 1.24 μg / mL; when the sample size is 0.25 g and the volume is adjusted to 50 mL, the limit of quantification for soluble dietary fiber is 0.221 × 25 × 100 / 1 / 1000 = 25 mg / 100 g.

[0121] (4) Precision test:

[0122] 4.1 Test Methods

[0123] Nine samples were weighed and divided into three groups of three samples each. 0.15g, 0.25g, and 0.35g of samples were weighed from each group, respectively. The soluble dietary fiber content in the samples was determined according to the method, and the RSD (%) was calculated.

[0124] 4.2 Experimental data (see Table 7):

[0125] Table 7 Precision test data for soluble dietary fiber

[0126]

[0127]

[0128] 4.3 Experimental Conclusions:

[0129] The RSD of soluble dietary fiber content in the 9 samples was 0.3%, indicating that the method has good precision and meets the requirements of GB / T27404-2008 "Laboratory Quality Control Standard" [GB / T 27404-2008 requires RSD≤1.3%].

[0130] (5) Durability test (stability study)

[0131] 5.1 Test Methods:

[0132] After the test solution and standard solution were placed at room temperature for 0h, 4h, 8h, 16h and 28h respectively, the peak area of ​​total dietary fiber and the peak area of ​​glucose were measured and their RSD (%) were calculated.

[0133] 5.2 Experimental data (results are shown in Table 8):

[0134] Table 8 Stability test data

[0135] 0h 4h 8h 16h 28h RSD, % Test solution 5278128 5296808 5305247 5312151 5327359 0.4 Standard solution 4224221 4226844 4230340 4245824 4275642 0.6

[0136] 5.3 Experimental Conclusions

[0137] After the test solution and standard solution were placed at room temperature for 0h, 4h, 8h, 16h and 28h respectively, the RSDs were 0.4% and 0.6% respectively, indicating that the test solution and standard solution had good stability at room temperature for 28 hours.

[0138] (6) Accuracy test (method comparison)

[0139] 6.1 Comparison Method:

[0140] The results of this method were compared with those of Method II in GB / T 22224-2008 Determination of Dietary Fiber in Food by Enzyme Gravimetric Method and Enzyme Gravimetric Method-Liquid Chromatography.

[0141] 6.2 Test Methods:

[0142] According to the comparison method requirements, 6 samples were weighed, the soluble dietary fiber content was determined, and the average value was calculated.

[0143] 6.3 Experimental Data:

[0144] The test data of Method II of GB / T 22224-2008 Determination of Dietary Fiber in Food by Enzyme Gravimetric Method and Enzyme Gravimetric Method-Liquid Chromatography are summarized in Table 9.

[0145] Table 9 shows the soluble dietary fiber content in the comparative methods.

[0146]

[0147] Wherein, mSDF—the mass of soluble dietary fiber precipitated in ethanol by a high molecular weight;

[0148] mRMD—the quality of non-precipitable soluble dietary fiber.

[0149] Table 10 shows a comparison of the results from the verification method and the comparison method:

[0150] Table 10 Comparison of data results from the two methods

[0151] Validation methods (Table 7), % Comparison methods (Table 9), % 92.52 92.57

[0152] 6.4 Experimental Conclusions:

[0153] The relative deviation of the test results from the two testing methods is 0.1%, which is less than 1%, meeting the requirements of GB / T27404-2008 "Laboratory Quality Control Standard" [GB / T 27404-2008 requires <5%].

[0154] The linearity, precision, robustness (stability), specificity (blank method), limit of detection, limit of quantitation, and accuracy (method comparison) tests of the soluble dietary fiber content determination method all meet the requirements of GB / T 27404-2008 "Laboratory Quality Control Standards", proving that the content determination method is scientific and effective and can achieve the purpose of quality control of the soluble dietary fiber content in soluble dietary fiber raw materials.

[0155] Finally, it should be noted that the above content is only used to illustrate the technical solution of the present invention, and is not intended to limit the scope of protection of the present invention. Simple modifications or equivalent substitutions made by those skilled in the art to the technical solution of the present invention do not depart from the essence and scope of the technical solution of the present invention.

Claims

1. A method for detecting soluble dietary fiber in resistant dextrin, characterized in that, The resistant dextrin was enzymatically digested using amylase, and the solution was diluted with water to obtain the test solution. Using glucose as a standard, the soluble dietary fiber content in the resistant dextrin was determined by high-performance liquid chromatography (HPLC) using the external standard method. The specific steps are as follows: (1) Preparation of standard solution: Add the standard to water and dissolve it to obtain the solution; (2) Preparation of blank solution: Add amyloglucosidase to Tris buffer, digest with enzymes, and then filter to obtain the blank solution; (3) Preparation of test solution: Add resistant dextrin and amyloglucosidase to Tris buffer, digest with enzymes, add water to make up to volume, and filter to obtain the solution; (4) Inject the standard solution, blank solution, and test solution into the high performance liquid chromatograph for testing; (5) The soluble dietary fiber content in the resistant dextrin of the test sample was calculated by external standard method after removing the blank. The standard is D-glucose; In step (5), the calculation process of the soluble dietary fiber content is as follows: first, subtract the area of ​​the blank solution from the peak area of ​​the glucose polymer in the test sample solution to obtain the peak area of ​​the soluble dietary fiber, and then compare it with the peak area of ​​the glucose standard solution to calculate the content of soluble dietary fiber in the test sample. The conditions for the high-performance liquid chromatography are as follows: Chromatographic column: gel guard column and two gel chromatography columns in series; Column temperature: 70℃; the gel guard column has dimensions of 6.0mm × 40mm and 6μm; the gel chromatography column has dimensions of 7.8mm × 300mm and 6μm. Detector: Differential refractive index detector, detection temperature 50℃; Mobile phase: Primary water; Flow rate: 0.5 mL / min; Injection volume: 50 μL.

2. The detection method according to claim 1, characterized in that, The concentration of the standard solution is 3-8 g / L.

3. The detection method according to claim 1, characterized in that, In steps (2) and (3), the amyloglucosidase accounts for 0.10-0.50% of the volume of the Tris buffer.

4. The detection method according to claim 1, characterized in that, In step (3), the concentration of the resistant dextrin in Tris buffer is 3-8 g / L.

5. The detection method according to claim 1, characterized in that, In steps (2) and (3), the enzymatic hydrolysis temperature is 58-60℃ and the enzymatic hydrolysis time is 0.5-2h.

6. The detection method according to claim 1, characterized in that, The peak area of ​​the glucose polymer is the peak area of ​​the glucose polymer with DP≥3.

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