Quality control detection method for chlorate and perchlorate in food

Abstract

The invention discloses a preparation method of an infant milk powder-based chlorate and perchlorate standard sample, which comprises the following steps: step 1, accurately weighing sodium chlorate and sodium perchlorate high-purity substances, and adding into first-grade water to prepare chlorate and perchlorate solutions; step 2, quantitatively weighing matrix milk powder, adding primary water to restore the matrix milk powder into an emulsion, accurately and quantitatively adding chlorate and perchlorate solutions, and performing high-pressure homogenization to obtain an emulsion solution; step 3, drying the emulsion solution in the step 2 in a spray dryer with low air inlet temperature to obtain milk powder; and step 4, performing vacuum drying on the milk powder in the step 3 at low temperature until the water content in the milk powder does not exceed 2.0%. The invention also discloses a baby milk powder base chlorate and perchlorate standard sample which has the characteristics of uniformity, stability and accurate fixed value, and can be used for accurately and stably performing quality control on the detection process of the baby milk powder base chlorate and perchlorate.

Description

[0001] This application is a divisional application of application number 2020108170379, the invention name is a method for preparing a standard sample of chlorate and perchlorate based on infant formula milk powder, and the original application date is August 14, 2020 Technical Field

[0002] The invention belongs to the technical field of food detection, and in particular relates to a quality control detection method for chlorate and perchlorate in food. Background Art

[0003] Chlorate is a disinfection by-product that is harmful to the human body, and perchlorate is a new type of persistent chemical pollutant. The cleaning and disinfection links in milk powder production and the contamination migration of milk powder packaging materials may cause residual contamination of chlorate and perchlorate.

[0004] Chlorate and perchlorate have been detected in infant formula milk powder from many brands in countries such as the United States and Germany. These two substances can hinder the synthesis and secretion of human thyroid hormone, leading to metabolic dysfunction and affecting the normal growth and development of the nervous center of infants and young children. In 2007, the World Health Organization set a daily safe dose of chlorate and perchlorate in food. In 2018, my country's State Food and Drug Administration included chlorate and perchlorate in the risk monitoring project for infant formula milk powder. At present, my country detects chlorate and perchlorate in accordance with the method of BJS201706 "Determination of Chlorate and Perchlorate in Food". However, my country currently lacks a quality control method for the detection of chlorate and perchlorate content in infant formula milk powder. It is impossible to assess and analyze whether the detection process of the existing chlorate and perchlorate determination method is controlled, whether the personnel operation of the detection process is standardized, etc., and thus it is impossible to determine whether the test results (i.e., chlorate and perchlorate content values) obtained by the determination method are accurate and reliable. Summary of the invention

[0005] The inventor of this case has found through research that the standard samples of chlorate and perchlorate based on infant formula milk powder with accurate and stable content can be developed as quality control samples in the determination method of chlorate and perchlorate in food, so as to solve the problem that the detection of chlorate and perchlorate content in infant formula milk powder is difficult and the numerical value has deviations due to the lack of standard samples of chlorate and perchlorate based on infant formula milk powder in my country. Therefore, the first purpose of the present invention is to provide a method for preparing standard products of chlorate and perchlorate based on infant formula milk powder, so as to obtain uniform and stable standard samples of chlorate and perchlorate based on infant formula milk powder, and ensure that the content detection of chlorate and perchlorate is accurate and reliable. The second purpose of the present invention is to provide a standard sample of chlorate and perchlorate based on infant formula milk powder. The standard sample of chlorate and perchlorate based on infant formula milk powder can be used for laboratory analysis method verification and analysis capability assessment of chlorate and perchlorate content detection, and can also provide guarantee for testing institutions to conduct milk powder detection technology research and infant formula milk powder enterprise quality and safety risk analysis, and can also provide scientific and fair basis and technical support for government supervision. The third object of the present invention is to provide the use of the infant formula-based chlorate and perchlorate standard samples in the quality control monitoring of chlorate and perchlorate in food.

[0006] In order to achieve the above object, the present invention provides the following technical solutions:

[0007] A quality control detection method for chlorate and perchlorate in food, using infant formula-based chlorate and perchlorate standard samples for detection; the preparation method of the infant formula-based chlorate and perchlorate standard samples comprises the following steps:

[0008] Step 1: Preparation of chlorate and perchlorate solutions

[0009] Accurately weigh high-purity sodium chlorate and sodium perchlorate and add them to primary water to prepare chlorate and perchlorate solutions;

[0010] Step 2: Preparation of chlorate and perchlorate concentrations in base milk powder

[0011] Quantitatively weigh the base milk powder, add primary water to reconstitute into an emulsion, accurately quantitatively add chlorate and perchlorate solutions, and homogenize by high pressure to make the chlorate and perchlorate dispersed evenly in the emulsion to obtain an emulsion solution;

[0012] Step 3, low inlet air temperature spray drying: drying the emulsion solution in step 2 into milk powder in a spray dryer with low inlet air temperature;

[0013] Step 4, vacuum drying: vacuum drying the milk powder in step 3 at low temperature until the moisture content in the milk powder does not exceed 2.0%.

[0014] Furthermore, the matrix milk powder is a matrix milk powder that complies with the national standards GB 10767-2010 "National Food Safety Standard for Older Infants and Young Children Formula" and GB 10765-2010 "National Food Safety Standard for Infant Formula".

[0015] Furthermore, the vacuum drying temperature in step 4 is 45°C-70°C, and the vacuum degree is 0.08-0.09MPa.

[0016] Furthermore, the method further comprises step five, packaging: quantitatively packaging the milk powder prepared in step four into aluminum foil bags, and heat-sealing the bags after nitrogen filling.

[0017] Furthermore, the method further comprises step six, content and uniformity test: randomly sampling the milk powder prepared in step four or step five, and conducting chlorate and perchlorate content test and uniformity test.

[0018] Furthermore, the method includes step seven, stability monitoring: the milk powder-based chlorate and perchlorate standards that have passed the inspection in step six are stored in the dark, and short-term stability monitoring is performed at gradient temperatures and long-term stability monitoring is performed at room temperature.

[0019] Furthermore, the gradient temperatures for short-term stability monitoring are -25°C, 0°C, 20°C, and 40°C; and the time for short-term stability monitoring is 1 week.

[0020] Furthermore, the long-term stability monitoring period was 1 year, including 0, 0.5, 1, 3, 6, and 12 months.

[0021] The beneficial effects of the present invention are:

[0022] 1. The infant formula milk powder-based chlorate and perchlorate standard samples obtained by the preparation method of the present invention are characterized by being uniform, stable and having accurate values, and can accurately and stably control the quality of the detection process of chlorate and perchlorate in infant formula milk powder, and can be applied to the assessment of laboratory analysis capabilities and the research on the detection method of infant formula milk powder; and the content range of the standard samples is wide, and they are suitable for the detection of chlorate and perchlorate based on infant formula milk powder with different chlorate and perchlorate contamination conditions.

[0023] 2. By using the composite technology of low air inlet temperature spray drying and vacuum drying, a finished milk powder of about 2% can be obtained. The finished product content of chlorate and perchlorate is consistent with the design value. At the same time, it is not easy to form charred powder during the spray drying process. Chlorate and perchlorate can exist evenly and stably in the finished product. DETAILED DESCRIPTION

[0024] The present invention will be further described below in conjunction with specific examples. It should be understood that the following examples are only used to illustrate the present invention and are not intended to limit the scope of the present invention. The experimental methods in the following examples where specific conditions are not specified are usually carried out under conventional conditions.

[0025] 1. The matrix milk powder of the following examples

[0026] According to BJS201706 "Determination of Chlorate and Perchlorate in Food", the contents of chlorate and perchlorate in the matrix milk powder were accurately determined to be 20.2μg / kg and 11.9μg / kg respectively.

[0027] It should be noted that the content of chlorate and perchlorate in commercially available matrix milk powders varies greatly, and the matrix milk powder selected by the present invention has relatively low content of chlorate and perchlorate. Meanwhile, the matrix milk powder of the embodiments of the present invention can be derived from matrix milk powder on the market that meets the national standards GB 10767-2010 "National Food Safety Standard for Formulated Foods for Older Infants and Young Children" and GB10765-2010 "National Food Safety Standard for Infant Formulated Foods", and can be operated according to the steps of the embodiments of the present invention.

[0028] 2. Preparation of the following examples of chlorate standard solution and perchlorate standard solution

[0029] Accurately weigh 0.128g of sodium chlorate (CAS: 7775-09-9, purity > 99%) and 0.123g of sodium perchlorate (CAS: 7601-89-0) in a 1000ml volumetric flask after constant weight, and add first-grade water specified in GB / T 6682 to the scale. After sealing, shake for 30 minutes to prepare chlorate standard solution and perchlorate standard solution, with concentrations of 100mg / L (calculated as chlorate and perchlorate), respectively.

[0030] 3. Pre-prepared low-concentration infant formula-based chlorate and perchlorate standard samples and high-concentration infant formula-based chlorate and perchlorate standard samples

[0031] (1) Low-concentration infant formula-based chlorate and perchlorate standard samples: chlorate content is 70 μg / kg, and perchlorate content is 20 μg / kg;

[0032] According to calculation, to prepare the standard sample of milk powder with chlorate content of 70μg / kg and perchlorate content of 20μg / kg, 50μl of chlorate solution and 8μl of perchlorate solution should be added for every 100g of milk powder.

[0033] (2) High-concentration infant formula-based chlorate and perchlorate standard samples: chlorate content is 200 μg / kg, and perchlorate content is 100 μg / kg;

[0034] According to calculation, to prepare standard milk powder samples with a chlorate content of 200 μg / kg and a perchlorate content of 100 μg / kg, 180 μl of chlorate solution and 88 μl of perchlorate solution should be added per 100 g of milk powder.

[0035] Example 1 Preparation method of low concentration infant formula based chlorate and perchlorate standard samples

[0036] Accurately weigh 500.00 g of base milk powder, add 1000.0 ml of first-grade water specified in GB / T 6682, stir to dissolve, add 250 μl of chlorate solution and 40 μl of perchlorate solution, homogenize at 100 MPa for 2 times, and stir the emulsion evenly.

[0037] Spray drying at an inlet air temperature of 130°C gave a chlorate or perchlorate milk powder with a moisture content of 5.3%; drying at a temperature of 45°C and a vacuum degree of 0.09 MPa for 24 hours gave a chlorate or perchlorate milk powder with a moisture content of 1.8%.

[0038] After testing, the obtained low-concentration infant formula-based chlorate and perchlorate standard samples were consistent with the preset concentrations (chlorate content of 70 μg / kg and perchlorate content of 20 μg / kg), indicating that the preparation process was successful.

[0039] Example 2 Preparation method of low concentration infant formula based chlorate and perchlorate standard samples

[0040] Accurately weigh 500.00 g of base milk powder, add 1000.0 ml of first-grade water specified in GB / T 6682, stir to dissolve, add 250 μl of chlorate solution and 40 μl of perchlorate solution, homogenize at 100 MPa for 2 times, and stir the emulsion evenly.

[0041] Spray drying at an inlet air temperature of 135°C gave a chlorate or perchlorate milk powder with a moisture content of 4.8%; drying at a temperature of 45°C and a vacuum degree of 0.09 MPa for 18 hours gave a chlorate or perchlorate milk powder with a moisture content of 1.7%.

[0042] After testing, the obtained low-concentration infant formula-based chlorate and perchlorate standard samples were consistent with the preset concentrations, indicating that the preparation process was successful.

[0043] Example 3 Preparation method of low concentration infant formula based chlorate and perchlorate standard samples

[0044] Accurately weigh 500.00 g of base milk powder, add 1000.0 ml of first-grade water specified in GB / T 6682, stir to dissolve, add 250 μl of chlorate solution and 40 μl of perchlorate solution, and homogenize at 100 MPa for 2 times.

[0045] Spray drying at an inlet air temperature of 140°C gave a chlorate or perchlorate milk powder with a moisture content of 4.2%; drying at a temperature of 45°C and a vacuum degree of 0.09 MPa for 15 hours gave a chlorate or perchlorate milk powder with a moisture content of 1.5%.

[0046] After testing, the obtained low-concentration infant formula-based chlorate and perchlorate standard samples were consistent with the preset concentrations, indicating that the preparation process was successful.

[0047] Comparative Example 1 Preparation method of low-concentration infant formula powder-based chlorate and perchlorate standard samples

[0048] Accurately weigh 500.00 g of base milk powder, add 1000.0 ml of first-grade water specified in GB / T 6682, stir to dissolve, add 250 μl of chlorate solution and 40 μl of perchlorate solution, and homogenize at 100 MPa for 2 times.

[0049] The product was spray dried at an inlet air temperature of 170°C to obtain chlorate and perchlorate milk powder with a moisture content of 2.0%.

[0050] After testing, the chlorate and perchlorate content in the standard samples of low-concentration infant formula were 61.5μg / kg and 25.4μg / kg respectively, which was inconsistent with the designed addition amount, with chlorate being too low and perchlorate being too high.

[0051] Conclusion: Using a higher air inlet temperature will result in a lower chlorate content and a higher perchlorate content in the finished product. Moreover, burnt powder is easily produced during the spray drying process. Therefore, this preparation process is not suitable for preparing low-concentration infant formula-based chlorate and perchlorate standard samples, and no subsequent uniformity and stability tests were conducted.

[0052] Example 4 Homogeneity test of low concentration infant formula based chlorate and perchlorate standard products

[0053] The milk powders of Examples 1 to 3 were packaged in 8-gram packages, nitrogen-filled and heat-sealed, and 10 samples were randomly selected for inspection.

[0054] The homogeneity test of the prepared standard samples was carried out by one-way analysis of variance F test. According to the significance level α = 0.05 and the degree of freedom (9, 10), F was obtained from the F distribution critical value table. 0.05 (9, 10) = 3.02. After testing, the F values ​​of chlorate and perchlorate are 0.444 and 1.15 respectively. A <F 0.05 (9,10) This indicates that there is no significant difference between the groups and that the samples are uniform. The results are shown in Tables 1 and 2.

[0055] Table 1. Chlorate (low concentration) uniformity test data of physical standard samples of infant formula milk powder (result unit: μg / kg)

[0056]

[0057]

[0058] Table 2. Perchlorate (low concentration) uniformity test data of standard samples of infant formula milk powder (result unit: μg / kg)

[0059]

[0060]

[0061] Example 5 Stability Monitoring of Low-Concentration Infant Formula-Based Chlorate and Perchlorate Standards

[0062] The milk powders of Examples 1 to 3 were packaged in 8-gram packages, nitrogen-filled and heat-sealed, and 20 samples were randomly selected for inspection.

[0063] The linear regression trend analysis t-test method was used to monitor the short-term stability of -25℃, 0℃, 20℃, and 40℃ gradient temperatures for 1 week and the long-term stability of 0, 0.5, 1, 3, 6, and 12 months at room temperature. The results were consistent with │b1│<t (0.95，n-2) ·s (b1) .

[0064] (1) The short-term stability monitoring data and statistical results are shown in Tables 3 and 4.

[0065] Table 3 Short-term stability test results of chlorate (low concentration) of physical standard samples of infant formula milk powder

[0066]

[0067]

[0068] Table 4 Short-term stability test results of perchlorate (low concentration) of physical standard samples of infant formula milk powder

[0069]

[0070]

[0071] (2) Long-term stability monitoring data and statistical results are shown in Tables 5 to 8.

[0072] Table 5 Long-term stability test results of chlorate (low concentration) of physical standard samples of infant formula milk powder

[0073]

[0074] Table 6 Linear fitting and statistical parameters of long-term stability test of chlorate (low concentration) of infant formula milk powder physical standard sample

[0075] <![CDATA[b0]]> <![CDATA[|b1|]]> s <![CDATA[s (b1) ]]> <![CDATA[t (0.95,11) ]]> <![CDATA[t (0.95,11) *s (b1) ]]> <![CDATA[S t ]]> <![CDATA[S t Square]]> Significance 69.18 0.0349 0.382 0.0240 2.20 0.0527 0.29 0.08 no

[0076] Table 7 Long-term stability test results of perchlorate (low concentration) of physical standard samples of infant formula milk powder

[0077]

[0078] Table 8 Linear fitting and statistical parameters of long-term stability test of perchlorate (low concentration) of physical standard samples of infant formula milk powder

[0079] <![CDATA[b0]]> <![CDATA[|b1|]]> s <![CDATA[s (b1) ]]> <![CDATA[t (0.95,11) ]]> <![CDATA[t (0.95,11) *s (b1) ]]> <![CDATA[S t ]]> <![CDATA[S t Square]]> Significance 19.67 0.00491 0.186 0.0114 2.20 0.0251 0.14 0.02 no

[0080] The results show that the standard samples of Examples 1-3 can be stably stored during short-term transportation and have no long-term change trend within 12 months.

[0081] Example 6 Preparation method of high concentration infant formula based chlorate and perchlorate standard

[0082] Accurately weigh 500.00 g of base milk powder, add 1000.0 ml of first-grade water specified in GB / T 6682, stir to dissolve, add 900 μl of chlorate solution and 440 μl of perchlorate solution, and homogenize at 100 MPa for 2 times.

[0083] Spray drying at an inlet air temperature of 130°C gave a chlorate or perchlorate milk powder with a moisture content of 5.2%; drying at a temperature of 45°C and a vacuum degree of 0.09 MPa for 24 hours gave a chlorate or perchlorate milk powder with a moisture content of 1.8%.

[0084] Example 7 Preparation method of high concentration infant formula based chlorate and perchlorate standard

[0085] Accurately weigh 500.00 g of base milk powder, add 1000.0 ml of first-grade water specified in GB / T 6682, stir to dissolve, add 900 μl of chlorate solution and 440 μl of perchlorate solution, and homogenize at 100 MPa for 2 times.

[0086] Spray drying at an inlet air temperature of 135°C gave a chlorate or perchlorate milk powder with a moisture content of 4.6%; drying at a temperature of 45°C and a vacuum degree of 0.09 MPa for 18 hours gave a chlorate or perchlorate milk powder with a moisture content of 1.6%.

[0087] Example 8 Preparation method of high concentration infant formula based chlorate and perchlorate standard

[0088] Accurately weigh 500.00 g of base milk powder, add 1000.0 ml of first-grade water specified in GB / T 6682, stir to dissolve, add 900 μl of chlorate solution and 440 μl of perchlorate solution, and homogenize at 100 MPa for 2 times.

[0089] Spray drying at an inlet air temperature of 140°C gave a chlorate or perchlorate milk powder with a moisture content of 4.0%; drying at a temperature of 45°C and a vacuum degree of 0.09 MPa for 15 hours gave a chlorate or perchlorate milk powder with a moisture content of 1.4%.

[0090] After testing, the obtained high-concentration infant formula-based chlorate and perchlorate standard samples were consistent with the preset concentrations, indicating that the preparation process was successful.

[0091] Comparative Example 2 Preparation method of high-concentration infant formula powder-based chlorate and perchlorate standard products

[0092] Accurately weigh 500.00 g of base milk powder, add 1000.0 ml of first-grade water specified in GB / T 6682, stir to dissolve, add 250 μl of chlorate solution and 40 μl of perchlorate solution, and homogenize at 100 MPa for 2 times.

[0093] Spray drying at an inlet air temperature of 170°C gave chlorate and perchlorate milk powder with a moisture content of 1.8%.

[0094] After testing, the chlorate and perchlorate contents in the high-concentration infant formula chlorate and perchlorate standard samples were 189μg / kg and 113μg / kg, respectively. This was inconsistent with the designed addition amount, with the chlorate content being low and the perchlorate content being high. Therefore, this preparation process was not suitable for preparing high-concentration infant formula-based chlorate and perchlorate standard samples, and no subsequent uniformity and stability tests were conducted.

[0095] Example 9 Homogeneity test of high concentration infant formula based chlorate and perchlorate standard products

[0096] The above-mentioned milk powder was packaged in 8g units, nitrogen-filled and heat-sealed, and 10 samples were randomly selected for inspection.

[0097] The homogeneity test of the prepared standard samples was carried out by one-way analysis of variance F test. According to the significance level α = 0.05 and the degree of freedom (9, 10), F was obtained from the F distribution critical value table. 0.05 (9, 10) = 3.02. After testing, the F values ​​of chlorate and perchlorate are 1.49 and 1.26 respectively. A <F 0.05 (9,10) It shows that there is no significant difference between the groups and the samples are uniform. See Table 9 and Table 10 for details.

[0098] Table 9 Uniformity test data of chlorate (high concentration) of physical standard samples of infant formula milk powder (result unit: μg / kg)

[0099]

[0100]

[0101] Table 10: Perchlorate (high concentration) uniformity test data of standard samples of infant formula milk powder (result unit: μg / kg)

[0102]

[0103]

[0104] Example 10 Stability Monitoring of High-Concentration Infant Formula-Based Chlorate and Perchlorate Standards The milk powders of Examples 1 to 3 were packaged in 8-gram units, nitrogen-filled and heat-sealed, and 20 samples were randomly selected for inspection.

[0105] The linear regression trend analysis t-test method was used to monitor the short-term stability of -25℃, 0℃, 20℃, and 40℃ gradient temperatures for 1 week and the long-term stability of 0, 0.5, 1, 3, 6, and 12 months at room temperature. The results were consistent with │b1│<t (0.95，n-2) ·s (b1) .

[0106] (1) Short-term stability monitoring data and statistical results are shown in 11-12.

[0107] Table 11 Results of short-term stability test of chlorate (high concentration) of physical standard samples of infant formula milk powder

[0108]

[0109]

[0110] Table 12 Results of short-term stability test of perchlorate (high concentration) of physical standard samples of infant formula milk powder

[0111]

[0112]

[0113] (2) Long-term stability monitoring data and statistical results are shown in Tables 13 to 16.

[0114] Table 13 Long-term stability test results of chlorate (high concentration) of physical standard samples of infant formula milk powder

[0115]

[0116] Table 14 Linear fitting and statistical parameters of long-term stability test of chlorate (high concentration) of infant formula milk powder physical standard sample

[0117] <![CDATA[b0]]> <![CDATA[|b1|]]> s <![CDATA[s (b1) ]]> <![CDATA[t (0.95,11) ]]> <![CDATA[t (0.95,11) *s (b1) ]]> <![CDATA[S t ]]> <![CDATA[S t Square]]> Significance 199.30 0.124 1.12 0.0690 2.20 0.152 0.83 0.68 no

[0118] Table 15 Long-term stability test results of perchlorate (high concentration) of physical standard samples of infant formula milk powder

[0119]

[0120] Table 16 Linear fitting and statistical parameters of long-term stability test of perchlorate (high concentration) of infant formula milk powder standard sample

[0121] <![CDATA[b0]]> <![CDATA[|b1|]]> s <![CDATA[s (b1) ]]> <![CDATA[t (0.95,11) ]]> <![CDATA[t (0.95,11) *s (b1) ]]> <![CDATA[S t ]]> <![CDATA[S t Square]]> Significance 98.76 0.0248 0.761 0.0466 2.20 0.103 0.56 0.31 no

[0122] The results show that the standard samples of Examples 6-8 can be stably stored during short-term transportation and have no long-term change trend within 12 months.

[0123] Example 11 Milk powder based chlorate and perchlorate standard samples Chlorate and chlorate content determination

[0124] The standard samples of Examples 1-3 and Examples 6-8 were calibrated by a joint calibration method of 8 institutions (Sichuan Food and Drug Inspection Institute, Zhejiang Food and Drug Inspection Institute, Chengdu Food and Drug Inspection Institute, Shanghai Food and Drug Inspection Institute, China Certification and Inspection Group Shanghai Co., Ltd., China Inspection and Certification (Shanghai) Testing Technology Co., Ltd., Shanghai Food Research Institute, Inner Mongolia Yili Industrial Group Co., Ltd.). The chlorate and perchlorate contents in the low-concentration infant formula chlorate and perchlorate standard samples were 70.8±7.0μg / kg and 19.4±1.9μg / kg, respectively. The chlorate and perchlorate contents in the high-concentration infant formula chlorate and perchlorate standard samples were 204±10μg / kg and 96.6±3.4μg / kg, respectively.

[0125] Example 12 Practical application of infant formula-based chlorate and perchlorate standard products

[0126] (1) Existing testing process

[0127] The commercially available brand infant formula milk powder stages 1, 2, and 3 were tested for chlorate and perchlorate according to the method of BJS201706 "Determination of chlorate and perchlorate in food". There were no accompanying physical standard samples during the pre-treatment extraction and machine loading process. The test results are shown in Table 17.

[0128] Table 17 Test results of chlorate and perchlorate content in infant formula milk powder stage 1, stage 2 and stage 3

[0129] Chlorate μg / kg Perchlorate μg / kg Infant formula stage 1 milk powder 45.6 198 Infant formula stage 2 milk powder 59.5 232 Infant formula stage 3 milk powder 66.3 212

[0130] The results showed that the perchlorate results were much higher than those of regular infant formula. After retesting, the results were still between 190-230μg / kg.

[0131] Analysis of results: The perchlorate content of infant formula is generally 20-100μg / kg, while the perchlorate content of these three milk powders is abnormal. Analysis of this phenomenon may be that on the one hand, the perchlorate content of the milk powder itself is relatively high, and on the other hand, it is also necessary to check for possible problems in the detection process.

[0132] (2) Testing of chlorate and perchlorate standard samples with infant formula

[0133] The above-mentioned brand of infant formula milk powder stage 1, stage 2, and stage 3 were tested for chlorate and perchlorate according to the method of BJS201706 "Determination of chlorate and perchlorate in food". The accompanying physical standard samples were brought in during the pre-treatment extraction and loading process, and the test results are shown in Table 18.

[0134] Table 18 Test results of chlorate and perchlorate content in infant formula milk powder stage 1, stage 2 and stage 3

[0135] Chlorate μg / kg Perchlorate μg / kg Infant formula stage 1 milk powder 46.7 189 Infant formula stage 2 milk powder 58.1 221 Infant formula stage 3 milk powder 65.1 210 Physical standard sample (low concentration) 69.7 193 Physical standard sample (high concentration) 203 265

[0136] The results showed that the low and high concentrations of chlorate in the physical standard sample were within the characteristic value range (low concentration 70.8±6.96μg / kg, high concentration 204±10.0μg / kg), proving that the chlorate results of the milk powder sample to be tested were controllable, while the low and high concentrations of perchlorate in the physical standard sample exceeded the characteristic value range (low concentration 19.4±1.85μg / kg, high concentration 96.6±3.35μg / kg), proving that there was a problem in a certain link of the detection process, which led to abnormal perchlorate results and needed to find the cause. After finding the cause, it was found that the extract was contaminated by perchlorate, which caused the sample to be contaminated during the extraction process.

[0137] After replacing the extraction solution, the test was conducted again. The accompanying physical standard samples were brought in during the pre-treatment extraction and machine operation. The test results are shown in Table 19.

[0138] Table 19 Test results of chlorate and perchlorate content in infant formula milk powder stage 1, stage 2 and stage 3

[0139] Chlorate μg / kg Perchlorate μg / kg Infant formula stage 1 milk powder 45.6 15.8 Infant formula stage 2 milk powder 59.5 58.7 Infant formula stage 3 milk powder 66.3 35.5 Physical standard sample (low concentration) 70.5 19.5 Physical standard sample (high concentration) 201 96.9

[0140] After replacing the extraction solution, the test results of perchlorate returned to normal. The test results of low and high concentrations of perchlorate in the standard sample were within the characteristic value range, indicating that there was no abnormality in the test process and the test results of the three milk powders were accurate and reliable.

[0141] Example 13: Verification of infant formula-based chlorate and perchlorate standards

[0142] (1) The chlorate and perchlorate standard solutions used in the test were incorrectly prepared (the concentrations of the standard curves were doubled).

[0143] The commercially available brand infant formula stage 2 milk powder was tested according to the method of BJS201706 "Determination of Chlorate and Perchlorate in Food". The accompanying physical standard samples were brought in during the pre-treatment extraction and loading process, and the test results are shown in Table 20.

[0144] Table 20 Test results of chlorate and perchlorate content in infant formula milk powder stage 1, stage 2 and stage 3

[0145] Chlorate μg / kg Perchlorate μg / kg Infant formula stage 2 milk powder 27.8 12.5 Physical standard sample (low concentration) 36.5 9.52 Physical standard sample (high concentration) 96.4 50.1

[0146] The results showed that although there was no obvious abnormality in the infant formula stage 2 milk powder, the characteristic values ​​of chlorate and perchlorate of the accompanying physical standard samples (chlorate low concentration 70.8±6.96μg / kg, high concentration 204±10.0μg / kg, perchlorate low concentration 19.4±1.85μg / kg, high concentration 96.6±3.35μg / kg) were much lower, indicating that there was an abnormality in the detection process.

[0147] (2) Prepare the standard solution normally and test again

[0148] The above-mentioned brand of infant formula stage 2 milk powder was tested for chlorate and perchlorate according to the method of BJS201706 "Determination of chlorate and perchlorate in food". The accompanying physical standard samples were brought in during the pre-treatment extraction and loading process, and the test results are shown in Table 21.

[0149] Table 21 Chlorate and perchlorate content test of infant formula milk powder stage 1, stage 2 and stage 3

[0150] Chlorate μg / kg Perchlorate μg / kg Infant formula stage 2 milk powder 58.5 25.8 Physical standard sample (low concentration) 69.5 20.1 Physical standard sample (high concentration) 198 98.8

[0151] The results showed that after preparing the standard solution of the correct concentration, the contents of chlorate and perchlorate in the accompanying physical standard samples were within the characteristic value range, indicating that there was no abnormality in the testing process and the test results of infant formula stage 2 milk powder obtained in this process were accurate and reliable.

Claims

1. A quality control detection method for chlorate and perchlorate in food, characterized in that: The standard samples of chlorate and perchlorate based on infant formula milk powder are used for detection; the preparation method of the standard samples of chlorate and perchlorate based on infant formula milk powder comprises the following steps: Step 1: Preparation of chlorate and perchlorate solutions Accurately weigh high-purity sodium chlorate and sodium perchlorate and add them to primary water to prepare chlorate and perchlorate solutions; Step 2: Preparation of chlorate and perchlorate concentrations in base milk powder Quantitatively weigh the base milk powder, add primary water to reconstitute into an emulsion, accurately quantitatively add chlorate and perchlorate solutions, and homogenize by high pressure to make the chlorate and perchlorate dispersed evenly in the emulsion to obtain an emulsion solution; Step 3, low inlet air temperature spray drying: drying the emulsion solution in step 2 into milk powder in a spray dryer with low inlet air temperature; Step 4, vacuum drying: vacuum drying the milk powder in step 3 at low temperature until the moisture content in the milk powder does not exceed 2.0%.

2. The quality control detection method according to claim 1, characterized in that: The matrix milk powder is a matrix milk powder that complies with the national standards GB10767-2010 "National Food Safety Standard for Formula for Older Infants and Young Children" and GB 10765-2010 "National Food Safety Standard for Infant Formula".

3. The quality control detection method according to claim 1, characterized in that: The temperature of vacuum drying in step 4 is 45°C-70°C, and the vacuum degree is 0.08-0.09MPa.

4. The quality control detection method according to claim 1, characterized in that: The method further comprises the step five of packaging: quantitatively packaging the milk powder prepared in the step four into aluminum foil bags, and heat-sealing the bags after nitrogen filling.

5. The quality control detection method according to claim 1 or 4, characterized in that: The method also includes step six, content and uniformity inspection: randomly sampling the milk powder prepared in step four or step five, and conducting chlorate and perchlorate content inspection and uniformity inspection.

6. The quality control detection method according to claim 5, characterized in that: The method also includes step seven, stability monitoring: the milk powder-based chlorate and perchlorate standards that have passed the inspection in step six are stored away from light, and short-term stability monitoring is performed at gradient temperatures and long-term stability monitoring is performed at room temperature.

7. The quality control detection method according to claim 6, characterized in that: The gradient temperatures for short-term stability monitoring were -25°C, 0°C, 20°C, and 40°C, respectively; the duration of short-term stability monitoring was 1 week.

8. The quality control detection method according to claim 6, characterized in that: The duration of long-term stability monitoring was 1 year, including 0, 0.5, 1, 3, 6, and 12 months.

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