A multi-element composite milk powder matrix quality control sample and a preparation method thereof

Abstract

The application provides a multi-element composite milk powder base quality control sample and a preparation method thereof. The quality control sample is prepared from the following raw materials by weight: raw milk: 8000-12000 parts, iron standard solution: 50-60 parts, zinc standard solution: 3-8 parts, lead standard solution: 0.10-0.15 parts, chromium standard solution: 0.40-0.80 parts, mercury standard solution: 0.02-0.06 parts, arsenic standard solution: 0.10-0.15 parts, secondary water: 250-350 parts, and stabilizer: 0.1-0.5 parts. The application inhibits the complex precipitation of metal ions and milk protein by means of chelating stabilizer, improves the element recovery rate and the uniformity and stability of the sample, the content of harmful elements in the sample is close to the national standard limit, the uncertainty is low after the joint value determination of multiple laboratories, six element detection quality controls can be realized at the same time, and the cost performance is excellent.

Description

Technical Field

[0001] This invention relates to the field of food testing technology, specifically to a multi-element composite milk powder matrix quality control sample and its preparation method. Background Technology

[0002] As a core ingredient in infant formula and various dairy products, milk powder's quality and safety directly impact consumers' health. Milk powder matrix quality control samples are crucial metrological tools for ensuring the accuracy, comparability, and traceability of test data. Currently, the metal elements in milk powder that require routine monitoring mainly fall into two categories: essential trace elements such as iron (Fe), zinc (Zn), copper (Cu), manganese (Mn), and selenium (Se); and toxic heavy metal contaminants such as lead (Pb), chromium (Cr), mercury (Hg), arsenic (As), and cadmium (Cd). The national food safety standard GB 2762-2022 sets strict limits for contaminants such as lead, cadmium, mercury, arsenic, and chromium in milk powder.

[0003] However, existing technologies for quality control samples of milk powder matrices have the following prominent problems: (1) The concentration range is out of touch with the actual problem: The characteristic values ​​of most commercially available heavy metal quality control samples are often 1-2 orders of magnitude higher than the detection limit of the national standard. For example, the characteristic value of lead is usually 0.5-2.0 mg / kg, while the lead limit for milk powder specified in GB 2762 is 0.2 mg / kg. Such high-concentration quality control samples cannot effectively monitor low-concentration pollution close to the limit value, resulting in a regulatory blind spot where high concentrations are measurable but low concentrations are out of control; (2) Limited variety of elements: There is a lack of quality control samples on the market that scientifically combine multiple essential trace elements with multiple toxic heavy metals and accurately determine their values. Quality control samples with single or a few elements cannot meet the needs of laboratories to evaluate the ability to detect multiple elements at one time, and the price of a single quality control sample is generally 800-1000 yuan / pack, and the high cost limits the routine use of small and medium-sized dairy companies; (3) Technical barriers exist in the preparation process: Milk powder matrix is ​​rich in protein. When metal ions are added directly, these ions will undergo strong complexation reactions with the thiol, imidazole, amino, and carboxyl groups of aspartic acid and methionine in milk protein, forming irreversible macromolecular complexes that precipitate. This phenomenon leads to a large loss of metal ions, and the actual content is far lower than the added value. Precipitation results in extremely uneven samples, making it impossible to pass subsequent uniformity tests. This is the core technical bottleneck limiting the development of quality control samples for low-concentration, multi-element composite milk powder matrix.

[0004] Therefore, developing a quality control sample for milk powder matrix that can simultaneously and stably add multiple metal elements, has characteristic values ​​covering a low concentration range, exhibits excellent uniformity and stability, and is cost-effective, and its preparation method is of significant practical importance and market value. Summary of the Invention

[0005] Based on the above background, the present invention provides a multi-element composite milk powder matrix quality control sample and its preparation method, which solves the technical problems in the preparation of existing low-concentration multi-element milk powder matrix quality control samples, such as the easy irreversible complexation and precipitation of metal ions and milk proteins, which leads to low element recovery rate, insufficient sample uniformity and stability, deviation of characteristic values ​​from the national standard lower limit, single type of composite elements, and high preparation cost.

[0006] To address the aforementioned technical problems, one objective of this invention is to provide a multi-element composite milk powder matrix quality control sample, which is prepared from the following raw materials in parts by weight: raw milk: 8000-12000 parts, iron standard solution: 50-60 parts, zinc standard solution: 3-8 parts, lead standard solution: 0.10-0.15 parts, chromium standard solution: 0.40-0.80 parts, mercury standard solution: 0.02-0.06 parts, arsenic standard solution: 0.10-0.15 parts, secondary water: 250-350 parts, and stabilizer: 0.1-0.5 parts.

[0007] Preferably, the concentration of the iron, zinc, lead, chromium, mercury, and arsenic standard solutions is 1 mg / mL.

[0008] Preferably, the raw milk is skimmed milk.

[0009] Preferably, the stabilizer is an aminopolycarboxylic acid chelating agent or a carboxymethyl amino acid chelating agent.

[0010] Based on the same inventive concept, the present invention also provides a method for preparing a quality control sample of a multi-element composite milk powder matrix, comprising the following steps: S1: Add the standard mixed solution of iron, zinc, lead, chromium, mercury and arsenic to secondary water and dilute and mix well; S2: Add the diluted and uniformly mixed solution to the raw milk, add a stabilizer, and mix well using a high-shear homogenizer to obtain a mixed emulsion; S3: The obtained mixed emulsion is spray-dried using a centrifugal spray dryer to obtain primary milk powder; S4: After sieving the primary milk powder, mix it using a V-type mixer to obtain a multi-element composite milk powder matrix quality control sample.

[0011] Preferably, in step S2, the high-shear homogenizing emulsifier operates at a speed of 8000-20000 rpm, and the mixing time is 0.5-2 hours.

[0012] Preferably, in step S3, the spray drying conditions are: inlet air temperature of 150-170℃, outlet air temperature of 75-85℃, and centrifugal speed of 280-320 Hz.

[0013] Preferably, in step S4, the mixing time is 0.5-2 hours.

[0014] The above-described one or more technical solutions of the present invention have the following technical effects: (1) This invention, for the first time, effectively solves the problems of precipitation and unevenness of metal ions in milk protein matrix through a synergistic strategy of "chelating agent stabilization + double mixing". Experiments show that after adding stabilizers, the spiked recovery rate of each metal element increases from 20%-60% without stabilizers to 90%-110%, and the uniformity F value decreases from above 5.0 to below 2.15, successfully preparing low-concentration quality control samples of six or more elements.

[0015] (2) The quality control samples prepared by this invention have harmful element characteristic values, such as lead 0.12 mg / kg and mercury 0.0478 mg / kg, which are close to the national standard limits. This can effectively evaluate the laboratory's detection capability near the key concentration point and avoid the risk of high concentration being qualified and low concentration being out of control.

[0016] (3) After rigorous testing, the uniformity F values ​​of all elements are less than the critical value F. 0.05 (9,10)=3.02, both the short-term and long-term stability values ​​|t| are less than the critical value t. 0.05 This demonstrates that the sample exhibits excellent homogeneity and long-term storage stability.

[0017] (4) Wide applicability and high cost-effectiveness: The method of this invention is not only applicable to six elements: iron, zinc, lead, chromium, mercury and arsenic, but can also be extended to multiple metal elements such as cadmium, copper, manganese, aluminum, nickel and selenium. Multiple quality control indicators can be completed in one test, and the raw material and process costs are controllable. It is expected to break the high-price monopoly of imported or high-end quality control samples and promote the popularization of quality control systems in small and medium-sized dairy enterprises. Detailed Implementation

[0018] This invention provides a multi-element composite milk powder matrix quality control sample and its preparation method, which solves the technical problems in the preparation of existing low-concentration multi-element milk powder matrix quality control samples, such as the easy irreversible complexation and precipitation of metal ions and milk proteins, which leads to low element recovery rate, insufficient sample uniformity and stability, deviation of characteristic values ​​from the national standard lower limit, single type of composite elements, and high preparation cost.

[0019] To address the aforementioned technical problems, this invention provides a multi-element composite milk powder matrix quality control sample, which is prepared from the following raw materials in parts by weight: raw milk: 8000-12000 parts, iron standard solution: 50-60 parts, zinc standard solution: 3-8 parts, lead standard solution: 0.10-0.15 parts, chromium standard solution: 0.40-0.80 parts, mercury standard solution: 0.02-0.06 parts, arsenic standard solution: 0.10-0.15 parts, secondary water: 250-350 parts, and stabilizer: 0.1-0.5 parts.

[0020] The concentration of the iron, zinc, lead, chromium, mercury, and arsenic standard solutions is 1 mg / mL.

[0021] The raw milk is skimmed milk.

[0022] The stabilizer is an aminopolycarboxylic acid chelating agent or a carboxymethyl amino acid chelating agent, which can form a soluble chelate with the target element ion and inhibit the complexation and precipitation of metal ions with milk protein through competitive chelation. An aminopolycarboxylic acid chelating agent, such as disodium ethylenediaminetetraacetate (EDTA), is preferred.

[0023] Based on the same inventive concept, the present invention also provides a method for preparing a quality control sample of a multi-element composite milk powder matrix, comprising the following steps: S1: Add the standard mixed solution of iron, zinc, lead, chromium, mercury and arsenic to secondary water and dilute and mix well; S2: Add the diluted and uniformly mixed solution to the raw milk, add a stabilizer, and mix well using a high-shear homogenizer to obtain a mixed emulsion; S3: The obtained mixed emulsion is spray-dried using a centrifugal spray dryer to obtain primary milk powder; S4: After sieving the primary milk powder, mix it using a V-type mixer to obtain a multi-element composite milk powder matrix quality control sample.

[0024] In step S2, the high-shear homogenizing emulsifier operates at a speed of 8000-20000 rpm, and the mixing time is 0.5-2 hours.

[0025] In S3, the spray drying conditions are: inlet air temperature of 150-170℃, outlet air temperature of 75-85℃, and centrifugal speed of 280-320 Hz.

[0026] In step S4, the mixing time is 0.5-2 hours.

[0027] The technical solution of the present invention will now be clearly and completely described in conjunction with the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0028] Throughout this specification, unless otherwise specified, the terminology used herein should be understood as having the meaning commonly used in the art. Therefore, unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. In the event of any conflict, this specification shall prevail.

[0029] Example 1 A method for preparing a quality control sample of a multi-element composite milk powder matrix includes the following steps: S1: Add 55.000 mL Fe standard solution (1 mg / mL), 5.000 mL Zn standard solution (1 mg / mL), 0.130 mL Pb standard solution (1 mg / mL), 0.600 mL Cr standard solution (1 mg / mL), 0.044 mL Hg standard solution (1 mg / mL), and 0.130 mL As standard solution (1 mg / mL) to 300 mL of secondary water and dilute and mix well. S2: Add the diluted and uniformly mixed solution to 10L of skim milk, and add 0.1% (w / w) of disodium ethylenediaminetetraacetate (EDTA). Mix the emulsion at 12000 rpm for 1.5 hours using a high-shear homogenizer to obtain a mixed emulsion. S3: The obtained mixed emulsion was spray-dried using a centrifugal spray dryer. The spray drying conditions were: inlet air temperature of 165℃, outlet air temperature of 80℃, and centrifugation speed of 310 Hz, to obtain primary milk powder. S4: After sieving the primary milk powder, mix it with a V-type mixer for 1 hour to obtain a multi-element composite milk powder matrix quality control sample.

[0030] Example 2 A method for preparing a quality control sample of a multi-element composite milk powder matrix includes the following steps: S1: Add 50.000 mL Fe standard solution (1 mg / mL), 3.000 mL Zn standard solution (1 mg / mL), 0.100 mL Pb standard solution (1 mg / mL), 0.400 mL Cr standard solution (1 mg / mL), 0.020 mL Hg standard solution (1 mg / mL), and 0.100 mL As standard solution (1 mg / mL) to 250 mL of secondary water and dilute and mix well. S2: Add the diluted and uniformly mixed solution to 10L of skim milk, and add 0.001% (w / w) of disodium ethylenediaminetetraacetate (EDTA). Mix the emulsion at 12000 rpm for 1.5 hours using a high-shear homogenizer to obtain a mixed emulsion. S3: The obtained mixed emulsion was spray-dried using a centrifugal spray dryer. The spray drying conditions were: inlet air temperature of 165℃, outlet air temperature of 80℃, and centrifugation speed of 310 Hz, to obtain primary milk powder. S4: After sieving the primary milk powder, mix it with a V-type mixer for 1 hour to obtain a multi-element composite milk powder matrix quality control sample.

[0031] Example 3 A method for preparing a quality control sample of a multi-element composite milk powder matrix includes the following steps: S1: Add 60.000 mL Fe standard solution (1 mg / mL), 8.000 mL Zn standard solution (1 mg / mL), 0.150 mL Pb standard solution (1 mg / mL), 0.800 mL Cr standard solution (1 mg / mL), 0.060 mL Hg standard solution (1 mg / mL), and 0.150 mL As standard solution (1 mg / mL) to 350 mL of secondary water and dilute and mix well. S2: Add the diluted and uniformly mixed solution to 10L of skim milk, and add 0.005% (w / w) of disodium ethylenediaminetetraacetate (EDTA). Mix the emulsion at 12000 rpm for 1.5 hours using a high-shear homogenizer to obtain a mixed emulsion. S3: The obtained mixed emulsion was spray-dried using a centrifugal spray dryer. The spray drying conditions were: inlet air temperature of 165℃, outlet air temperature of 80℃, and centrifugation speed of 310 Hz, to obtain primary milk powder. S4: After sieving the primary milk powder, mix it with a V-type mixer for 1 hour to obtain a multi-element composite milk powder matrix quality control sample.

[0032] Comparative Example 1 It is basically the same as Example 1, except that no stabilizer is added in S1.

[0033] To further verify the performance of the multi-element composite milk powder matrix quality control sample prepared by this invention, the following tests were conducted.

[0034] Test Example 1: Uniformity Test of Milk Powder Matrix Quality Control Samples Homogeneity tests were conducted within and between groups on quality control samples of iron, zinc, lead, chromium, mercury, and arsenic in the milk powder matrix. The test method is as follows: 10 packages were randomly selected from the same batch of samples (109 packages), and the corresponding national standard test methods were used to test for iron, zinc, lead, chromium, mercury, and arsenic. The same national standard method was used, and each package of samples was tested in parallel three times. One-way ANOVA was used for verification. If there was no significant difference in the characteristic values ​​of the samples, the samples were judged to be homogeneous. The specific test results are shown in Table 1.

[0035] Table 1. Results of multi-element homogeneity testing in milk powder matrix quality control samples

[0036] As shown in Table 1, the F values ​​of all elements in Example 1 range from 0.56 to 2.15, all of which are less than the critical value F for the homogeneity test. 0.05 (9,10)=3.02, and P The values ​​were all greater than 0.05, indicating that there were no significant differences within or between groups at a 95% confidence probability, and the sample homogeneity was good. However, in Comparative Example 1, due to the lack of a stabilizer, metal ions complexed and precipitated with milk proteins, resulting in F values ​​of 5.4–8.1 for each element, far exceeding the critical value, and indicating unacceptable homogeneity. These results demonstrate that the present invention, by adding a stabilizer, effectively inhibits the irreversible complexation reaction of metal ions, achieving a highly uniform distribution of multiple elements in the milk powder matrix, laying the foundation for subsequent value determination.

[0037] Test Example 2: Stability Testing of Milk Powder Matrix Quality Control Samples (1) Short-term stability test of milk powder matrix quality control samples The quality control samples of iron, zinc, lead, chromium, mercury, and arsenic in the milk powder matrix were placed in a light-protected environment at 4 ℃ to simulate a cold chain transportation environment. The samples were tested for iron, zinc, lead, chromium, mercury, and arsenic on days 1, 2, 3, 4, 5, 6, and 7. Three samples were selected each time, and each sample was measured twice in parallel according to the national standard method, controlling the relative standard deviation within the allowable range of the national standard. A t-test was performed on the test results. With a confidence probability of 95%, the probability of |t| occurring was compared by referring to the t-value degrees of freedom table. When the probability of |t| occurring was greater than 0.05, the hypothesis of the slope was considered significant, indicating no significant difference in stability; otherwise, it was not considered significant, indicating a significant difference in stability. The results of the short-term stability tests of multiple elements in the milk powder matrix quality control samples are shown in Table 2.

[0038] Table 2. Results of short-term stability tests of multiple elements in milk powder matrix quality control samples.

[0039] As shown in Table 2, the |t| values ​​of all elements in Example 1 under the 7-day short-term transportation simulation conditions range from 0.138 to 2.172, all of which are less than the critical value t. 0.05 (5) = 2.571, and P The values ​​are all greater than 0.05, indicating that the detected values ​​do not show a significant trend of change over time, and the samples can be stably stored for at least 7 days under cold chain transportation conditions at 4℃. In contrast, the |t| values ​​of each element in Comparative Example 1 are generally greater than 2.5, with some elements (such as lead and mercury) even exceeding 3.5. This indicates that the samples without stabilizers show significant fluctuations in metal content during short-term storage, and their stability cannot meet quality control requirements. The excellent short-term stability of this invention ensures that the characteristic values ​​of the samples do not change during actual express transportation, reducing the risk of use.

[0040] (2) Long-term stability test of milk powder matrix quality control samples The quality control samples of iron, zinc, lead, chromium, mercury, and arsenic in the milk powder matrix were placed in a light-protected environment at 4 ℃ to simulate a cold chain transportation environment. The samples were tested for iron, zinc, lead, chromium, mercury, and arsenic at 1, 2, 3, 4, 5, and 6 months. Three identical samples were selected each time and tested twice in parallel according to the national standard method. The relative standard deviation was within the national standard testing range. A t-test was performed on the test results. With a confidence probability of 95%, the probability of |t| occurring was compared using the t-value degrees of freedom table. When the probability of |t| occurring was greater than 0.05, the hypothesis of the slope was considered significant, indicating no significant difference in stability; otherwise, it was not considered significant, indicating a significant difference in stability. The long-term stability test results of multiple elements in the milk powder matrix quality control samples are shown in Table 3.

[0041] Table 3. Results of Long-Term Stability Testing of Multi-Elements in Milk Powder Matrix Quality Control Samples

[0042] As shown in Table 3, the |t| values ​​of all elements in Example 1 under the long-term storage condition of 6 months range from 0.151 to 1.667, all of which are less than the critical value t. 0.05 (5) = 2.571, P The values ​​are all greater than 0.05, indicating that the sample characteristics show no significant change trend under light-protected storage conditions at 4 ℃, demonstrating good long-term stability. In contrast, the |t| values ​​of Comparative Example 1 are generally greater than 2.5, with mercury even reaching 4.562, indicating that the complexation precipitation reaction not only affects initial homogeneity but also leads to continuous loss or transformation of metal elements during storage. The long-term stability advantage of this invention means that quality control samples have a longer shelf life, reducing the frequency of batch changes for users and lowering quality control costs.

[0043] Test Example 3: Fixed Value Detection of Milk Powder Matrix Quality Control Samples Referring to the national standard "Methods for Proficiency Testing Using Interlaboratory Comparison" (GB / T 28043-2019), eight qualified laboratories were commissioned to collaboratively determine values ​​using different testing methods specified in the national standard. Participating laboratories provided their value determination results and quality control results. Normality tests were performed on the test results to determine if they met a normal distribution. The Grubbs' test and Dixon's test were used to eliminate suspicious test data. Finally, the average value of the value determination results from the eight laboratories was calculated, which is the final value determination result. The multi-element value determination results in the milk powder matrix quality control samples are shown in Table 4.

[0044] Table 4. Results of multi-element determination in milk powder matrix quality control samples

[0045] As shown in Table 4, in Example 1, the characteristic values ​​of all elements, determined jointly by eight qualified laboratories, highly matched the theoretical values, with spiked recoveries ranging from 94.2% to 104.0% and relative standard deviations less than 10%. This demonstrates that the preparation method of this invention is accurate and reliable, and the determination results are traceable and credible. In contrast, the measured values ​​of each element in Comparative Example 1 were only 20% to 50% of the theoretical values, resulting in significant losses and making it impossible to obtain effective characteristic values. This indicates that without the addition of stabilizers, metal ions are largely precipitated or adsorbed by milk proteins before spray drying, leading to a significant deviation of the target element content in the final product from the design value. This invention achieves accurate determination of low-concentration multi-element composite quality control samples, filling the gap in the market for milk powder matrix quality control samples that closely match national standard limits.

[0046] Test Example 4: Verification of Laboratory Quality Control Results Involved in Fixed Value Testing To ensure the accuracy and stability of the value determination results, quality control evaluation of the test results from the participating laboratories is required. The evaluation criteria for quality control results include spike recovery rate and relative standard deviation. The quality control evaluation results of the participating laboratories are shown in Table 5.

[0047] Table 5. Quality control evaluation results during the determination of quality control samples for milk powder matrix.

[0048] As shown in Table 5, the spike recoveries of all participating laboratories in Example 1 were between 90% and 110%, and the relative standard deviations (RSDs) were all less than 10%, meeting the quality control requirements of GB / T 27417-2017 "Guideline for Conformity Assessment and Validation of Chemical Analysis Methods". This indicates that the matrix effect of the quality control samples of this invention is small, the detection method is highly adaptable, and consistent and reliable detection results can be obtained by different laboratories and different operators. In contrast, the spike recoveries of Comparative Example 1 were only 18% to 62%, and the RSDs were generally greater than 12%, with some elements having RSDs exceeding 25%. This indicates that the inhomogeneity and instability of the samples themselves seriously interfered with the accuracy of the detection process, making them unsuitable as quality control samples. The excellent quality control performance of this invention makes it suitable as a standard sample for proficiency testing, used to evaluate laboratory testing capabilities and personnel operational standardization.

[0049] Test Example 5: Uncertainty Analysis of Milk Powder Matrix Quality Control Samples Referencing the national standard "Methods for Proficiency Testing Using Inter-laboratory Comparison" (GB / T 28043-2019), the uncertainty of the milk powder matrix quality control samples is shown in Table 6.

[0050] Table 6 Uncertainty of quality control samples of milk powder matrix

[0051] As shown in Table 6, the total uncertainty (U) of each element in Example 1 is... total Both the expanded uncertainty (U, k=2) and the relative uncertainty (±0.03 mg / kg) of the sample are small. Specifically, the expanded uncertainty for lead is only ±0.03 mg / kg, and for mercury it is ±0.0089 mg / kg, with relative uncertainties between 5% and 12%, meeting the requirements for uncertainty of standard substances. In contrast, the uncertainty of Comparative Example 1 is significantly increased, approximately 3 to 5 times that of Example 1, with the expanded uncertainty even exceeding half of the measured value, making the assigned value unreliable. The low uncertainty of this invention stems from its homogeneity, stability, and highly controllable assignment process, ensuring the accuracy and confidence level (95%) of the characteristic values ​​and providing users with a reliable quality control basis.

Claims

1. A quality control sample for a multi-element composite milk powder matrix, characterized in that, The quality control samples are prepared from the following raw materials in parts by weight: raw milk: 8000-12000 parts, iron standard solution: 50-60 parts, zinc standard solution: 3-8 parts, lead standard solution: 0.10-0.15 parts, chromium standard solution: 0.40-0.80 parts, mercury standard solution: 0.02-0.06 parts, arsenic standard solution: 0.10-0.15 parts, secondary water: 250-350 parts, and stabilizer: 0.1-0.5 parts.

2. The quality control sample of the multi-element composite milk powder matrix according to claim 1, characterized in that: The concentration of the standard solutions for iron, zinc, lead, chromium, mercury, and arsenic is 1 mg / mL.

3. The quality control sample of the multi-element composite milk powder matrix according to claim 1, characterized in that: The raw milk is skimmed milk.

4. The quality control sample of the multi-element composite milk powder matrix according to claim 1, characterized in that: The stabilizer is an aminopolycarboxylic acid chelating agent or a carboxymethyl amino acid chelating agent.

5. A method for preparing a quality control sample of a multi-element composite milk powder matrix as described in any one of claims 1-4, characterized in that, The steps include the following: S1: Add the standard mixed solution of iron, zinc, lead, chromium, mercury and arsenic to secondary water and dilute and mix well; S2: Add the diluted and uniformly mixed solution to the raw milk, add a stabilizer, and mix well using a high-shear homogenizer to obtain a mixed emulsion; S3: The obtained mixed emulsion is spray-dried using a centrifugal spray dryer to obtain primary milk powder; S4: After sieving the primary milk powder, mix it using a V-type mixer to obtain a multi-element composite milk powder matrix quality control sample.

6. The method for preparing the quality control sample of the multi-element composite milk powder matrix according to claim 5, characterized in that: In step S2, the high-shear homogenizing emulsifier operates at a speed of 8000-20000 rpm, and the mixing time is 0.5-2 hours.

7. The method for preparing the quality control sample of the multi-element composite milk powder matrix according to claim 5, characterized in that: In S3, the spray drying conditions are: inlet air temperature of 150-170℃, outlet air temperature of 75-85℃, and centrifugal speed of 280-320Hz.

8. The method for preparing the quality control sample of the multi-element composite milk powder matrix according to claim 5, characterized in that: In step S4, the mixing time is 0.5-2 hours.

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