Method for detecting oxidation resistance of bamboo salt

Abstract

The invention provides a method for detecting oxidation resistance of bamboo salt. The method comprises the following steps: preparing a 50umol / L DPPH working solution, a series of ascorbic acid standard solutions with different concentrations and a bamboo salt sample solution to be detected; the series of ascorbic acid standard solutions and the bamboo salt sample solution to be detected are respectively and quantitatively reacted with the DPPH working solution, and the absorbance at the wavelength of 327 nm in an ultraviolet region is measured by using an ultraviolet and visible spectrophotometer; drawing a standard curve of the concentration of the ascorbic acid standard solution and the DPPH free radical scavenging rate; the ascorbic acid concentration equivalent to the clearance rate of the to-be-detected solution of the bamboo salt sample is quantitatively obtained through an external standard method, and then the corresponding ascorbic acid equivalent value is obtained. The method for detecting the oxidation resistance of the bamboo salt can quantify the oxidation resistance of the bamboo salt in a standardized manner, and is simple to operate and accurate in result.

Description

Technical Field

[0001] The present invention belongs to the technical field of antioxidant detection, and in particular relates to a method for detecting the antioxidant property of bamboo salt. Background Art

[0002] Table salt is an indispensable substance in human life. It is a necessity for humans to maintain normal physiological functions and an essential condiment in cooking and food processing. With the continuous development of society, the improvement of people's living standards and the increase in consumption levels, people's health awareness has become increasingly enhanced, and they have become particularly concerned about their own health conditions. People have gradually realized that health is closely and importantly related to the dietary structure. Ordinary table salt has gradually become unable to meet the needs of the vast number of consumers, and the development of multifunctional salt products with health care functions has become a new direction for the development of the salt industry. Antioxidation has always been one of the main research directions in the health care product and cosmetics industries, and it is also one of the most important functional demands in the market. Some table salts with antioxidant properties, such as bamboo salt, natural selenium-containing salt, and flavored salt added with antioxidant foods, have been favored by consumers.

[0003] Bamboo salt is made by using three-year-old young bamboo as a bamboo tube, filling the bamboo tube with sea salt, and then sealing both ends of the bamboo tube with natural red clay and firing the bamboo salt with pine wood as fuel at 1000-1500°C or above. The bamboo salt fired multiple times will form a molten state. After firing the bamboo salt up to 9 times, the color of the bamboo salt turns purple to become purple bamboo salt. In the sales market, the bamboo salts fired once, three times, and nine times are generally the main commodities. Now, bamboo salt, as a functional food with antioxidant properties, has entered the Chinese market and is not only used as a condiment in the food industry but also applied to chemical industries such as cosmetics and toothpaste.

[0004] Most of the evaluations of the antioxidant effect of bamboo salt adopt the 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging method. That is, a radical scavenger is added to the DPPH· radical solution, the lone pair electrons are paired, and the deep purple DPPH· radical is reduced to the yellow DPPH-H non-radical form. The degree of fading is quantitatively related to the number of electrons received, and then quantitative analysis is carried out through the change in absorbance. However, since there is no standardized experimental procedure for measuring the antioxidant property of bamboo salt by the DPPH method, different measurement results will be obtained under different experimental conditions, such as different reaction times, volume ratios, initial concentrations of DPPH· radicals, and result expressions, making it difficult to compare the results of different laboratories and different operation procedures. Therefore, there is an urgent need for a standardized method to quantify the antioxidant capacity.

[0005] The ascorbic acid equivalent (AAE) is an index used to represent the antioxidant strength. It quantifies the antioxidant property of a substance by comparing the antioxidant ability of the substance with that of a known antioxidant (ascorbic acid). Furthermore, it can provide a standardized method to quantify the antioxidant ability of a substance in terms of the ascorbic acid equivalent. However, due to the alkaline pH value of bamboo salt, this alkaline characteristic will affect the absorbance of DPPH· free radicals at a wavelength of 517 nm. At the same time, inorganic ions such as sodium chloride, potassium chloride, calcium, and magnesium in bamboo salt will also affect the color intensity of DPPH· free radicals, resulting in a non-linear relationship between the scavenging rate of DPPH· free radicals and different concentrations of bamboo salt solutions (as shown in Figure 1 ), so there are still significant problems in using the ascorbic acid equivalent to represent the antioxidant property of bamboo salt. Summary of the Invention

[0006] In view of this, to solve the above technical problems, the present invention proposes a method for detecting the antioxidant property of bamboo salt that can standardize and quantify the antioxidant ability of bamboo salt, is simple to operate, and has accurate results.

[0007] To achieve the above object, the technical solution of the present invention is realized as follows:

[0008] A method for detecting the antioxidant property of bamboo salt, characterized by comprising the following steps:

[0009] S1. Prepare solutions:

[0010] Prepare a DPPH working solution with a concentration of 50 μmol / L;

[0011] Prepare a series of ascorbic acid standard solutions with different concentrations;

[0012] Prepare a test solution of bamboo salt sample, and the concentration of the bamboo salt sample test solution is 1 - 20 g / L;

[0013] S2. Measure absorbance:

[0014] Mix and react different concentrations of ascorbic acid standard solutions with the DPPH working solution respectively, and use an ultraviolet-visible spectrophotometer to measure the absorbance at 327 nm; wherein, the volume ratio of different concentrations of ascorbic acid standard solutions to the DPPH working solution is 1:3;

[0015] Mix and react different concentrations of ascorbic acid standard solutions with the solvent for preparing the DPPH working solution respectively, and use an ultraviolet-visible spectrophotometer to measure the absorbance at 327 nm; wherein, the volume ratio of different concentrations of ascorbic acid standard solutions to the solvent for preparing the DPPH working solution is 1:3;

[0016] Mix the solvent for preparing the ascorbic acid standard solution with the DPPH working solution, and measure the absorbance at 327 nm using a UV-visible spectrophotometer; wherein, the volume ratio of the solvent for the ascorbic acid standard solution to the DPPH working solution is 1:3;

[0017] Mix the test solution of the bamboo salt sample with the DPPH working solution, and measure the absorbance at 327 nm using a UV-visible spectrophotometer; wherein, the volume ratio of the test solution of the bamboo salt sample to the DPPH working solution is 1:3;

[0018] Mix the test solution of the bamboo salt sample with the solvent for preparing the DPPH working solution, and measure the absorbance at 327 nm using a UV-visible spectrophotometer; wherein, the volume ratio of the test solution of the bamboo salt sample to the solvent for preparing the DPPH working solution is 1:3;

[0019] Mix the solvent for preparing the test solution of the bamboo salt sample with the DPPH working solution, and measure the absorbance at 327 nm using a UV-visible spectrophotometer; wherein, the volume ratio of the solvent for the test solution of the bamboo salt sample to the DPPH working solution is 1:3;

[0020] S3. Calculate the scavenging rate P1 of different concentrations of ascorbic acid standard solution on DPPH· free radicals and the scavenging rate P2 of the test solution of the bamboo salt sample on DPPH· free radicals according to formula (1):

[0021]

[0022] wherein, P is the scavenging rate; A sample is the absorbance of the mixture of the ascorbic acid standard solution or the test solution of the bamboo salt sample and the DPPH working solution; A blank is the absorbance of the mixture of the ascorbic acid standard solution or the test solution of the bamboo salt sample and the solvent for preparing the DPPH working solution; A contrast is the absorbance of the mixture of the solvent for preparing the ascorbic acid standard solution or the solvent for preparing the test solution of the bamboo salt sample and the DPPH working solution;

[0023] S4. Plot the standard curve:

[0024] Taking the ascorbic acid concentration as the abscissa and P1 as the ordinate, plot the standard curve showing a linear relationship between the ascorbic acid concentration and the scavenging rate P1;

[0025] S5. Evaluate the antioxidant property of the bamboo salt sample with the ascorbic acid equivalent value:

[0026] Substitute the obtained scavenging rate P2 into the standard curve to obtain the ascorbic acid concentration corresponding to this scavenging rate, and then calculate the ascorbic acid equivalent value through formula (2):

[0027]

[0028] Among them, AEAC is the ascorbic acid equivalent, with the unit of μgAE / g; c is the ascorbic acid concentration corresponding to the clearance rate P2 obtained by substituting it into the standard curve, with the unit of nmol / mL; c1 is the concentration of the bamboo salt sample solution to be measured, with the unit of g / L; M is the molar mass of ascorbic acid, with the unit of g / mol, (M = 176.12 g / mol).

[0029] By performing a full-wavelength scan on the DPPH solution, it is found that the DPPH· radical exhibits a strong absorption peak at 327 nm in the ultraviolet region. This is the characteristic absorption of its radical properties and decreases with the addition of the antioxidant ascorbic acid. Similarly, bamboo salt can also weaken the absorption value of the DPPH· radical at 327 nm in the ultraviolet region, and there is a linear relationship between different concentrations of bamboo salt solutions and the DPPH radical clearance rate within a certain range. Therefore, at a wavelength of 327 nm, the ascorbic acid concentration equivalent to the sample clearance rate can be quantitatively obtained by the external standard method, and then the antioxidant detection result of bamboo salt expressed in terms of ascorbic acid equivalent value can be obtained. In summary, the principle of this method is as follows: The DPPH· radical has a strong absorption peak at 327 nm in the ultraviolet region. Both bamboo salt and the standard substance ascorbic acid can quantitatively react with the DPPH· radical, weakening the characteristic absorption value of the DPPH· radical at a wavelength of 327 nm in the ultraviolet region. Moreover, different concentrations of bamboo salt solutions and standard substance ascorbic acid solutions both have a good linear relationship with the DPPH radical clearance rate within a certain range. Using a UV-visible spectrophotometer, with ascorbic acid as the standard, a standard curve of ascorbic acid concentration versus DPPH radical clearance rate is plotted. The ascorbic acid concentration equivalent to the bamboo salt clearance rate is quantitatively obtained by the external standard method, and then the antioxidant capacity of bamboo salt expressed by the ascorbic acid equivalent value can be obtained.

[0030] The concentration of the DPPH working solution is 50 μmol / L. The sensitivity range of the spectrophotometer is generally between 0.22 and 0.70. When the 50 μmol / L DPPH working solution is mixed with water in a volume ratio of 3:1, the absorbance is approximately 0.60, which is exactly within the sensitivity range of the spectrophotometer, ensuring the accuracy of the detection results.

[0031] The absorbance is measured after the DPPH working solution is mixed and reacted with the above-mentioned bamboo salt sample solution to be measured. The volume ratio of the DPPH working solution to the bamboo salt sample solution to be measured is 3:1 because within this volume range, the linear range of concentration versus clearance rate is the widest and the linear relationship is the best.

[0032] The concentration of the bamboo salt sample solution to be measured is 1 - 20 g / L because within this range, the linear relationship between the bamboo salt sample solution to be measured and the DPPH· radical clearance is good.

[0033] In some preferred embodiments of the method for detecting the antioxidant property of bamboo salt of the present invention, in the step S1, the preparation process of the DPPH working solution is as follows: Weigh 1,1-diphenyl-2-picrylhydrazyl and dissolve it in absolute ethanol, sonicate it in the dark to dissolve, and then make up the volume with absolute ethanol to a concentration of 50 μmol / L.

[0034] In some preferred embodiments of the method for detecting the antioxidant property of bamboo salt of the present invention, in the step S1, the preparation process of a series of ascorbic acid standard solutions with different concentrations is as follows: Weigh ascorbic acid and dissolve it in water to prepare ascorbic acid standard solutions with concentrations of 0 nmol / mL, 10 nmol / mL, 20 nmol / mL, 40 nmol / mL, 60 nmol / mL, 80 nmol / mL, 100 nmol / mL, and 200 nmol / mL.

[0035] The range of the ascorbic acid standard solution is 0 - 80 nmol / mL because there is a good linear relationship with the DPPH· radical scavenging rate within this range.

[0036] In some preferred embodiments of the method for detecting the antioxidant property of bamboo salt of the present invention, in the step S1, the preparation process of the bamboo salt sample solution to be measured is as follows: Weigh the bamboo salt sample and dissolve it in water to prepare a bamboo salt sample solution to be measured with a concentration in the range of 1 - 20 g / L.

[0037] In some preferred embodiments of the method for detecting the antioxidant property of bamboo salt of the present invention, the concentration of the bamboo salt sample solution to be measured is 10 g / L.

[0038] When the concentration of the bamboo salt sample solution to be measured is in the range of 1 - 20 g / L, the linear relationship with the scavenging rate is good. When the concentration of the bamboo salt sample solution to be measured is prepared to be 10 g / L, it is within the linear range of the linear regression equation of the solution concentration and the scavenging rate. Therefore, the concentration of the sample determination solution is preferably 10 g / L, which is convenient for preparation and ensures the accuracy of the measurement result.

[0039] In some preferred embodiments of the method for detecting the antioxidant property of bamboo salt of the present invention, in the step S2, the reaction conditions after mixing different liquids are all to seal after mixing, react in the dark for 30 min, and then measure the absorbance at 327 nm using an ultraviolet-visible spectrophotometer.

[0040] Compared with the prior art, the method for detecting the antioxidant property of bamboo salt of the present invention has the following advantages:

[0041] (1) The method for detecting the antioxidant property of bamboo salt according to the present invention utilizes the fact that both bamboo salt and the standard substance ascorbic acid can react quantitatively with DPPH· free radicals, weakening the characteristic absorption value of DPPH· free radicals at a wavelength of 327 nm in the ultraviolet region. Moreover, different concentrations of bamboo salt solutions and ascorbic acid standard substance solutions have a good linear relationship with the DPPH· free radical scavenging rate within a certain range at a wavelength of 327 nm in the ultraviolet region. Therefore, the concentration of ascorbic acid equivalent to the scavenging rate of bamboo salt can be quantitatively obtained by the external standard method, and then the detection result of the antioxidant property of bamboo salt expressed by the ascorbic acid equivalent value can be obtained, thus realizing the standardization and quantification of the antioxidant property of bamboo salt and solving the problem that the results of different laboratories and different operation procedures are difficult to compare;

[0042] (2) In the method for detecting the antioxidant property of bamboo salt according to the present invention, when the concentration of the DPPH working solution is 50 μmol / L and the volume ratio of the bamboo salt sample solution to be measured and the DPPH working solution is 1:3, the linear relationship between the concentration and the DPPH· free radical scavenging rate curve is good (R = 0.9964), and the linear range is wide (reaching 0 - 30 g / L); when the volume ratio of the ascorbic acid standard solution and the DPPH working solution is 1:3, there is a good linear relationship between the ascorbic acid concentration in the range of 0 - 80 nmol / mL and the DPPH· free radical scavenging rate (R = 0.9923); by defining the above-mentioned many conditions, it can be ensured that different concentrations of bamboo salt solutions and ascorbic acid standard substance solutions have a good linear relationship with the DPPH· free radical scavenging rate at a wavelength of 327 nm in the ultraviolet region, ensuring the accuracy of the results. Description of the Drawings

[0043] Figure 1 It is the relationship curve between the concentration of the bamboo salt solution and the corresponding DPPH· free radical scavenging rate at a wavelength of 517 nm described in the background art;

[0044] Figure 2 It is the relationship curve between the concentration of the bamboo salt sample solution to be measured and the corresponding DPPH· free radical scavenging rate at a wavelength of 327 nm obtained according to Scheme 1 in Example 2;

[0045] Figure 3 It is the relationship curve between the concentration of the bamboo salt sample solution to be measured and the corresponding DPPH· free radical scavenging rate at a wavelength of 327 nm obtained according to Scheme 2 in Example 2;

[0046] Figure 4 It is the relationship curve between the concentration of the bamboo salt sample solution to be measured and the corresponding DPPH· free radical scavenging rate at a wavelength of 327 nm obtained according to Scheme 3 in Example 2;

[0047] Figure 5 It is the relationship curve between the concentration of the ascorbic acid standard solution and the corresponding DPPH· free radical scavenging rate at a wavelength of 327 nm in Example 3;

[0048] Figure 6 The standard curve is a linear relationship between the concentration of the ascorbic acid standard solution at a wavelength of 327 nm and the corresponding DPPH· free radical scavenging rate in Example 3;

[0049] Figure 7 The curve is the relationship between the absorbance and the different reaction time after the test solution of the nine-roasted bamboo salt with a concentration of 10 g / L and the DPPH working solution were mixed at a volume ratio of 1:3 in Example 5. DETAILED DESCRIPTION

[0050] Unless otherwise defined, the technical terms used in the following examples have the same meanings as those generally understood by those skilled in the art to which the present invention belongs. The test reagents used in the following examples, unless otherwise specified, are all conventional biochemical reagents; the experimental methods, unless otherwise specified, are all conventional methods.

[0051] The present invention will be described in detail below with reference to the embodiments and the accompanying drawings.

[0052] In the following examples, unless otherwise specified, each solution was prepared as follows, all reagents used were analytically pure, and water was grade III water as specified in GB / T 6682:

[0053] Preparation of DPPH working solution: Weigh 1.9 mg of 1,1-diphenyl-2-trinitrophenylhydrazine (purity ≥ 95%), dissolve in 30 mL of anhydrous ethanol, protect from light and sonicate to fully dissolve, and then use anhydrous ethanol to make the volume to 100.0 ml to obtain a DPPH working solution with a concentration of 50 umol / L. This solution should be prepared and used immediately.

[0054] Preparation of ascorbic acid standard working solution: 1) Accurately weigh 0.1761 g (accurate to 0.0001 g) of ascorbic acid (L type, purity ≥ 98%) in a 100 mL volumetric flask, dilute to scale with water, mix well, and obtain a 0.01 mol / L ascorbic acid standard stock solution; 2) Dilute the ascorbic acid standard stock solution 100 times to obtain a 100 nmol / mL ascorbic acid standard working solution. This solution is prepared before use.

[0055] Preparation of bamboo salt sample mother solution: Weigh 10.00g of bamboo salt sample, add water to make up to 50mL, mix thoroughly, and prepare 200g / L bamboo salt sample mother solution.

[0056] Example 1

[0057] Selection of DPPH working solution concentration.

[0058] The sensitivity range of the spectrophotometer is generally between 0.22 and 0.70. When the 50 μmol / L DPPH working solution is mixed with the aqueous solution in a volume ratio of 3:1, the absorbance is approximately 0.60, which is exactly within the sensitivity range of the spectrophotometer. Therefore, the concentration of the DPPH working solution is 50 μmol / L.

[0059] Example 2

[0060] Determination of the volume ratio of the bamboo salt sample test solution to the DPPH working solution.

[0061] The prepared mother liquor of the bamboo salt sample (here, the bamboo salt sample is selected as the nine-roasted bamboo salt) is diluted with distilled water to different multiples to obtain test solutions of the bamboo salt sample with different concentrations. Add the solutions in the following three schemes in a clean test tube. After sealing and shaking well, react in the dark for half an hour, and then measure the absorbance value at 327 nm using a UV-visible spectrophotometer. Calculate the scavenging rate through Equation (1), plot the curve of concentration vs. scavenging rate, and calculate the linear equation R2.

[0062] Scheme 1: Sample: 1 ml of the bamboo salt sample test solution + 3 ml of the DPPH working solution, A sample ;

[0063] Sample blank: 1 ml of the bamboo salt sample test solution + 3 ml of absolute ethanol, A blank ;

[0064] Control: 1 ml of distilled water + 3 ml of the DPPH working solution, A contrast ;

[0065] Scheme 2: Sample: 2 ml of the bamboo salt sample test solution + 4 ml of the DPPH working solution, A sample ;

[0066] Sample blank: 2 ml of the bamboo salt sample test solution + 4 ml of absolute ethanol, A blank ;

[0067] Control: 2 ml of distilled water + 4 ml of the DPPH working solution, A contrast

[0068] Scheme 3: Sample: 2 ml of the bamboo salt sample test solution + 2 ml of the DPPH working solution, A sample ;

[0069] Sample blank: 2 ml of the bamboo salt sample test solution + 2 ml of absolute ethanol, A blank ;

[0070] Control: 2 ml of distilled water + 2 ml of the DPPH working solution, A contrast .

[0071] Calculate the scavenging rate according to the following formula:

[0072]

[0073] Where: P—the clearance rate;

[0074] A sample —the absorbance of the mixed solution of the test solution of the bamboo salt sample and the DPPH working solution;

[0075] A blank —the absorbance of the mixed solution of the test solution of the bamboo salt sample and absolute ethanol;

[0076] A contrast —the absorbance of the mixed solution of distilled water and the DPPH working solution.

[0077] As Figure 2 , 3 , as shown in Figure 4, when the volume ratio of the test solution of the bamboo salt sample to the DPPH working solution is 1:3, the linear range of the concentration and the clearance rate is the widest and the linear relationship is the best.

[0078] Example 3

[0079] Determination of the linear range of the ascorbic acid standard solution

[0080] Take the ascorbic acid standard stock solution, add water, and prepare ascorbic acid standard solutions with concentrations of 0 nmol / mL, 10 nmol / mL, 20 nmol / mL, 40 nmol / mL, 60 nmol / mL, 80 nmol / mL, 100 nmol / mL, and 200 nmol / mL respectively. Add the solutions in a clean test tube according to the following scheme. After sealing and shaking well, react in the dark for half an hour, and then measure the absorbance value at 327 nm with a UV-visible spectrophotometer. Calculate the clearance rate through the formula, plot the concentration-clearance rate curve, and calculate the linear equation R 2 .

[0081] Scheme: Sample: 1 ml of ascorbic acid standard solution + 3 ml of DPPH working solution, A sample ;

[0082] Sample blank: 1 ml of ascorbic acid standard solution + 3 ml of absolute ethanol, A blank ;

[0083] Control: 1 ml of distilled water + 3 ml of DPPH working solution, A contrast ;

[0084] Calculate the clearance rate according to the following formula:

[0085]

[0086] Where: P—the clearance rate;

[0087] A sample —— Absorbance of the mixed solution of ascorbic acid standard solution and DPPH working solution;

[0088] A blank —— Absorbance of the mixed solution of ascorbic acid standard solution and absolute ethanol;

[0089] A contrast —— Absorbance of the mixed solution of distilled water and DPPH working solution.

[0090] As Figure 5 , 6 shown, it can be seen that there is a good linear relationship between the ascorbic acid concentration in the range of 0 - 80 nmol / mL and the DPPH· radical scavenging rate.

[0091] Example 4

[0092] Determination of the concentration of the bamboo salt sample solution to be measured

[0093] Bamboo salts are divided into ordinary bamboo salt, nine - roasted molten bamboo salt, and low - sodium bamboo salt according to different production processes. Therefore, bamboo salts produced by different types and different manufacturers were purchased from the sales market. The sample details are shown in Table 1. Each bamboo salt sample was prepared into a mother liquor of the bamboo salt sample. Each mother liquor of the bamboo salt sample was diluted with distilled water to different multiples to obtain bamboo salt sample solutions to be measured with different concentrations. Taking the concentration of the bamboo salt sample solution to be measured as the abscissa and the scavenging rate as the ordinate, a linear equation of the bamboo salt sample solution to be measured and the scavenging rate was established (R 2 ≥0.9500). The linear data of the solutions with different concentrations of 6 bamboo salt samples and the scavenging rate are shown in Tables 2 to 7 below. It can be seen from Tables 2 to 7 that when the concentration of the bamboo salt sample solution to be measured is in the range of 1 - 20 g / L, the linear relationship with the scavenging rate is good. When the concentration of the sample solution to be measured is 10 g / L, it is within the linear range of the linear regression equation of the solution concentration and the scavenging rate. Therefore, the concentration of the sample determination solution was set at 10 g / L.

[0094] Table 1 Sample details

[0095]

[0096] Table 2 Sample 1#

[0097]

[0098] Table 3 Sample 2#

[0099]

[0100] Table 4 Sample 3#

[0101]

[0102] Table 5 Sample 4#

[0103]

[0104]

[0105] Table 6 Sample 5#

[0106]

[0107] Table 7 Sample 6#

[0108]

[0109] Example 5

[0110] Determination of the reaction time between the bamboo salt sample test solution and the DPPH working solution.

[0111] The mother solution of bamboo salt sample prepared by nine roasted bamboo salt was diluted with distilled water to different multiples to obtain bamboo salt sample test solutions of different concentrations. The concentration of bamboo salt sample test solution with a clearance rate of about 10%, i.e. 10g / L, was mixed with DPPH working solution at a volume ratio of 1:3, sealed and shaken, and reacted in the dark. The reaction time was 5min, 10min, 15min, 20min, 25min, 30min, 35min, and 40min respectively. The absorbance value at 327nm was measured with a UV-visible photometer. Figure 7 As shown, after the reaction time reaches 30 minutes, the absorbance changes slowly. From the perspective of saving time, 30 minutes is the optimal reaction time.

[0112] Example 6

[0113] Precision and Trueness Test

[0114] Taking the nine-roasted bamboo salt as an example, its ascorbic acid equivalent value was first measured, and then 10g / L high-grade pure sodium chloride solution was used as the base, and 0.5 times, 1 times, and 2 times the ascorbic acid equivalent value of the sample were added for determination. Each level was measured 7 times in parallel, and the relative standard deviation and recovery rate were calculated, as shown in Table 8. From the data in Table 8, it can be seen that the precision of bamboo salt determination is between 1.61% and 3.48%, and the recovery rate is between 92.55% and 102.54%. Both meet the requirements of GB / T 27417-2017 "Guidelines for Confirmation and Validation of Chemical Analysis Methods for Conformity Assessment".

[0115] Table 8

[0116]

[0117] Example 7

[0118] Antioxidant capacity test of bamboo salt samples

[0119] Antioxidant activity tests were conducted on samples of Nine - Roasted Bamboo Salt 1#, Nine - Roasted Bamboo Salt 2#, Three - Roasted Bamboo Salt 3#, Flavored Bamboo Salt 4#, Low - Sodium Bamboo Salt 5#, and Bamboo - Scented Low - Sodium Salt 6#. The testing steps are as follows:

[0120] S1. Prepare solutions: Prepare a DPPH working solution with a concentration of 50 μmol / L, using anhydrous ethanol as the solvent; prepare ascorbic acid standard solutions with concentrations of 0 nmol / mL, 10 nmol / mL, 20 nmol / mL, 40 nmol / mL, 60 nmol / mL, 80 nmol / mL, 100 nmol / mL, and 200 nmol / mL, using water as the solvent; prepare 6 kinds of bamboo salt sample test solutions with a concentration of 10 g / L, using water as the solvent.

[0121] S2. Measure absorbance:

[0122] Add the solutions to clean test tubes according to the following plan. After sealing and shaking well, react in the dark for half an hour, and then measure the absorbance at 327 nm using a UV - visible spectrophotometer.

[0123] Plan 1: Sample: 1 ml of a series of ascorbic acid standard solutions + 3 ml of the DPPH working solution, A sample ;

[0124] Sample blank: 1 ml of a series of ascorbic acid standard solutions + 3 ml of anhydrous ethanol, A blank ;

[0125] Control: 1 ml of distilled water + 3 ml of the DPPH working solution, A contrast ;

[0126] Plan 2: Sample: 1 ml of the bamboo salt sample test solution + 3 ml of the DPPH working solution, A sample ;

[0127] Sample blank: 1 ml of the bamboo salt sample test solution + 3 ml of anhydrous ethanol, A blank ;

[0128] Control: 1 ml of distilled water + 3 ml of the DPPH working solution, A contrast ;

[0129] S3. Calculate the scavenging rate P1 of ascorbic acid standard solutions with different concentrations for DPPH· free radicals and the scavenging rate P2 of the bamboo salt sample test solution for DPPH· free radicals according to formula (1):

[0130]

[0131] where P is the scavenging rate; A sampleIt is the absorbance of the mixed solution of ascorbic acid standard solution or the solution to be measured of bamboo salt sample and DPPH working solution; A blank It is the absorbance of the mixed solution of ascorbic acid standard solution or the solution to be measured of bamboo salt sample and the solvent for preparing DPPH working solution; A contrast It is the absorbance of the mixed solution of the solvent for preparing ascorbic acid standard solution or the solvent for preparing the solution to be measured of bamboo salt sample and DPPH working solution;

[0132] S4. Plot the standard curve:

[0133] Taking the ascorbic acid concentration as the abscissa and P1 as the ordinate, plot the standard curve of the ascorbic acid concentration and the scavenging rate P1;

[0134] S5. Evaluate the antioxidant property of the bamboo salt sample with the ascorbic acid equivalent value:

[0135] Substitute the scavenging rate P2 of the obtained 6 kinds of bamboo salt samples into the standard curve to obtain the ascorbic acid concentration corresponding to the respective scavenging rates of the 6 kinds of bamboo salt samples, and then calculate the ascorbic acid equivalent values of the 6 kinds of bamboo salt samples through formula (2):

[0136]

[0137] Among them, AEAC is the ascorbic acid equivalent, with the unit of ugAE / g; c is the ascorbic acid concentration corresponding to the scavenging rate obtained by substituting the scavenging rate P2 into the standard curve, with the unit of nmol / mL; c1 is the concentration of the solution to be measured of the bamboo salt sample, with the unit of g / L; M is the molar mass of ascorbic acid, with the unit of g / mol, (M = 176.12 g / mol).

[0138] The antioxidant capacities of the 6 kinds of bamboo salt samples are expressed by the ascorbic acid equivalent values. The test results are shown in Table 9. It can be seen that the antioxidant property of the nine-baked bamboo salt is higher than that of the ordinary bamboo salt and the low-sodium bamboo salt.

[0139] Table 9

[0140]

[0141] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for detecting the antioxidant property of bamboo salt, characterized in that, It includes the following steps: S1. Prepare solutions: Prepare a DPPH working solution with a concentration of 50 μmol / L; Prepare a series of ascorbic acid standard solutions with different concentrations; Prepare a test solution of the bamboo salt sample, and the concentration of the test solution of the bamboo salt sample is 1 - 20 g / L; S2. Measure absorbance: Mix the ascorbic acid standard solutions with different concentrations with the DPPH working solution respectively for reaction, and use an ultraviolet-visible spectrophotometer to measure the absorbance at 327 nm; among them, the volume ratio of the ascorbic acid standard solutions with different concentrations to the DPPH working solution is 1:3; Mix the ascorbic acid standard solutions with different concentrations with the solvent for preparing the DPPH working solution respectively for reaction, and use an ultraviolet-visible spectrophotometer to measure the absorbance at 327 nm; among them, the volume ratio of the ascorbic acid standard solutions with different concentrations to the solvent for preparing the DPPH working solution is 1:3; Mix the solvent for preparing the ascorbic acid standard solution with the DPPH working solution for reaction, and use an ultraviolet-visible spectrophotometer to measure the absorbance at 327 nm; among them, the volume ratio of the solvent for the ascorbic acid standard solution to the DPPH working solution is 1:3; Mix the test solution of the bamboo salt sample with the DPPH working solution for reaction, and use an ultraviolet-visible spectrophotometer to measure the absorbance at 327 nm; among them, the volume ratio of the test solution of the bamboo salt sample to the DPPH working solution is 1:3; Mix the test solution of the bamboo salt sample with the solvent for preparing the DPPH working solution for reaction, and use an ultraviolet-visible spectrophotometer to measure the absorbance at 327 nm; among them, the volume ratio of the test solution of the bamboo salt sample to the solvent for preparing the DPPH working solution is 1:3; Mix the solvent for preparing the test solution of the bamboo salt sample with the DPPH working solution for reaction, and use an ultraviolet-visible spectrophotometer to measure the absorbance at 327 nm; among them, the volume ratio of the solvent for the test solution of the bamboo salt sample to the DPPH working solution is 1:3; S3. Calculate the scavenging rate P1 of the ascorbic acid standard solutions with different concentrations on DPPH· free radicals and the scavenging rate P2 of the test solution of the bamboo salt sample on DPPH· free radicals according to formula (1): Wherein, P is the clearance rate; A sample is the absorbance of the mixed solution of ascorbic acid standard solution or the solution to be measured of bamboo salt sample and DPPH working solution; A blank is the absorbance of the mixed solution of ascorbic acid standard solution or the solution to be measured of bamboo salt sample and the solvent for preparing DPPH working solution; A contrast is the absorbance of the mixed solution of the solvent for preparing ascorbic acid standard solution or the solvent for preparing the solution to be measured of bamboo salt sample and DPPH working solution; S4. Draw a standard curve: Take the ascorbic acid concentration as the abscissa and P1 as the ordinate to draw a standard curve showing a linear relationship between the ascorbic acid concentration and the scavenging rate P1; S5. Evaluate the antioxidant property of the bamboo salt sample with the ascorbic acid equivalent value: Substitute the obtained scavenging rate P2 into the standard curve to obtain the ascorbic acid concentration corresponding to this scavenging rate, and then calculate the ascorbic acid equivalent value through formula (2): Among them, AEAC is the ascorbic acid equivalent, with the unit of μgAE / g; c is the ascorbic acid concentration corresponding to the scavenging rate P2 obtained by substituting it into the standard curve, with the unit of nmol / mL; c1 is the concentration of the test solution of the bamboo salt sample, with the unit of g / L; M is the molar mass of ascorbic acid, with the unit of g / mol.

2. The bamboo salt antioxidant detection method according to claim 1, wherein: In the above S1, the preparation process of the DPPH working solution is as follows: Weigh 1,1-diphenyl-2-picrylhydrazine and dissolve it in absolute ethanol, dissolve it by ultrasonic treatment in the dark, and then make up the volume to a concentration of 50 μmol / L with absolute ethanol.

3. The bamboo salt antioxidant detection method according to claim 1, characterized in that: In S1, the preparation process of a series of ascorbic acid standard solutions with different concentrations is as follows: Weigh ascorbic acid and dissolve it in water to prepare ascorbic acid standard solutions with concentrations of 0 nmol / mL, 10 nmol / mL, 20 nmol / mL, 40 nmol / mL, 60 nmol / mL, 80 nmol / mL, 100 nmol / mL, and 200 nmol / mL.

4. The bamboo salt antioxidant detection method according to claim 1, characterized in that: In S1, the preparation process of the bamboo salt sample solution to be measured is as follows: Weigh the bamboo salt sample and dissolve it in water to prepare a bamboo salt sample solution to be measured with a concentration in the range of 1 - 20 g / L.

5. The bamboo salt antioxidant detection method according to claim 4, characterized in that: The concentration of the bamboo salt sample solution to be measured is 10 g / L.

6. The bamboo salt antioxidant detection method according to claim 1, wherein: In S2, the reaction conditions after mixing different liquids are all to seal after mixing and react in the dark for 30 min, and then use a UV-visible spectrophotometer to measure the absorbance at 327 nm.

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