A method for detecting heavy metal content in food additives

Abstract

This invention belongs to the field of detection technology, specifically relating to a method for detecting the heavy metal content in food additives. The detection method includes the following steps: (1) sample pretreatment; (2) preparing a series of heavy metal standard solutions of different concentrations, testing their net strength using an ICP-MS instrument, and obtaining a standard working curve; (3) testing the net strength of the sample solution and blank solution using an ICP-MS instrument, and obtaining the concentration of heavy metals in the food additives by combining the standard working curves, and further obtaining the content of heavy metals in the food additives. The detection method of this invention can be used to detect the heavy metal arsenic in compound meat product thickeners. Through enzymatic hydrolysis-assisted extraction and ultrasonic synergistic extraction, gradient ultrasound combined with temperature control is used to further destroy the sample structure and improve the arsenic dissolution efficiency; EDTA and citric acid are used to complex metal ions, and multiple components synergistically reduce the fixation effect of other ions on arsenic. Through synergistic effect, the accuracy of the detection results is improved.

Description

Technical Field

[0001] This invention belongs to the field of detection technology, specifically relating to a method for detecting the heavy metal content in food additives. Background Technology

[0002] With the rapid development of the food industry, compound food additives are widely used in food processing due to their functional diversity and ease of processing. However, the heavy metal arsenic (As) that may remain in compound additives has become an important risk factor for food safety due to its high toxicity and cumulative harm.

[0003] Currently, the detection of arsenic in compound additives mainly relies on wet digestion-atomic fluorescence spectrometry and dry ashing. However, these methods have the following problems: wet digestion requires a large amount of strong acid (nitric acid, sulfuric acid, etc.), and the digestion process requires multiple acid replenishments and strict temperature control to avoid carbonization, making the operation cumbersome and prone to generating harmful gases; dry ashing requires long-term high-temperature ashing, which may lead to arsenic volatilization loss and large fluctuations in recovery rate. Meanwhile, the complex composition of compound additives (such as those containing phosphates, organic acids, etc.) may inhibit arsenic reduction or complex with detection reagents, leading to false negatives or signal suppression. Existing technologies often address this through multiple dilutions or separation and purification, but this prolongs the detection cycle.

[0004] Chinese patent CN104198417B discloses a method for determining the heavy metal arsenic in compound food additives. The compound food additive sample is prepared into a sample solution by wet digestion. Using graphite furnace atomic absorption spectrometry (GF-AAS), under illumination, the sample is introduced into an atomizer and undergoes three steps: drying, ashing, and atomization. The sample then enters an optical system, a monochromator, a detector, and electronic circuitry to detect its absorbance. The intensity is directly proportional to the absorbance. A standard curve method is used for quantitative measurement to calculate the total arsenic content in the compound food additive.

[0005] Compound meat product thickeners are food additives specifically designed to improve the texture, mouthfeel, and stability of meat products. They are typically formulated with a combination of multiple single thickeners, stabilizers, and other functional ingredients to enhance the water-holding capacity, elasticity, and shape retention of meat products, while preventing separation or water separation. Qingdao Dehui Marine Biotechnology Co., Ltd.'s compound meat product thickeners (… Figure 1 This product holds a significant market share and is widely recognized by industry clients, particularly in the production of frozen fish paste (shrimp paste) products such as fish balls, crab sticks, shrimp paste, fish paste, fish tofu, and cuttlefish balls. However, due to differences in national standards regarding heavy metal content in food additives, food manufacturers need to implement quality management tailored to the specific requirements of their target markets. Furthermore, the accuracy of current technologies for determining arsenic content in compound meat product thickeners is not ideal due to the complexity of the matrix, the forms in which arsenic exists, and potential interference during pretreatment.

[0006] The article "Simultaneous Detection of Common Food Additives and Heavy Metals in Food by Reversed-Phase HPLC-ICP-MS" (Yan Tingzhao, et al.) discloses the use of zinc sulfate and potassium ferrous hydride for pretreatment of food additives. However, the accuracy of this method for detecting arsenic in compound meat thickeners is not good.

[0007] Therefore, there is an urgent need for a method specifically for detecting the heavy metal content of food additives in compound meat thickeners. Summary of the Invention

[0008] The purpose of this invention is to provide a method for detecting the heavy metal content in food additives.

[0009] To achieve the above objectives, the present invention provides the following technical solution:

[0010] A method for detecting heavy metal content in food additives includes the following steps:

[0011] (1) Sample pretreatment:

[0012] A: Weigh the food additives and add water, add papain and neutral protease, hydrolyze, inactivate the enzymes, continue to add auxiliary extraction solution, mix evenly, perform gradient sonication, centrifuge after completion, take the supernatant, filter with a filter membrane, wash the filtrate with water into a volumetric flask, add rhodium solution as an internal standard element, dilute with water to the mark of the volumetric flask, shake well, and use as the sample solution.

[0013] B: Add papain and neutral protease to water, heat to inactivate enzymes, continue to add auxiliary extraction solution, then add rhodium solution as internal standard element, dilute to the mark of volumetric flask with water, shake well, and use as blank solution;

[0014] (2) Prepare a series of heavy metal standard solutions of different concentrations, test their net strength using an ICP-MS instrument, and obtain a standard working curve;

[0015] (3) The net strength of the sample solution and blank solution was tested using an ICP-MS instrument. Combined with the standard working curve, the concentration of heavy metals in the food additive was obtained, and the content of heavy metals in the food additive was further obtained.

[0016] Furthermore, the method includes the following steps:

[0017] (1) Sample pretreatment:

[0018] A: Weigh 5g of food additive, accurate to 0.0001g, add 100mL of water, add papain and neutral protease, enzymatically hydrolyze at 35-37℃ for 4-5h, inactivate the enzyme in a boiling water bath for 10 minutes, continue to add 250mL of auxiliary extraction solution, mix well, and then perform gradient sonication. After the process is complete, centrifuge for 10-15min, take the supernatant, filter it using a filter membrane, wash the filtrate with water into a 500mL volumetric flask, add 10mL of 50μg / L rhodium solution as an internal standard element, dilute to the mark of the volumetric flask with water, shake well, and use as the sample solution;

[0019] B: Add papain and neutral protease to 100mL of water, heat at 35-37℃ for 4-5 hours, inactivate the enzymes in a boiling water bath for 10 minutes, add 250mL of auxiliary extraction solution, then add 10mL of 50μg / L rhodium solution as an internal standard element, dilute to the mark of a 500mL volumetric flask with water, shake well, and use as a blank solution.

[0020] (2) Prepare a series of heavy metal standard solutions of different concentrations, test their net strength using an ICP-MS instrument, and obtain a standard working curve;

[0021] (3) The net strength of the sample solution and blank solution was tested using an ICP-MS instrument. Combined with the standard working curve, the concentration of heavy metals in the food additive was obtained, and the content of heavy metals in the food additive was further obtained.

[0022] Furthermore, the food additive is a compound meat product thickener.

[0023] Furthermore, the heavy metal is arsenic.

[0024] Furthermore, in step (1), the amounts of papain and neutral protease are both 0.5-1 wt% of the food additive.

[0025] This invention utilizes a synergistic extraction process involving enzymatic hydrolysis and ultrasonic extraction of auxiliary extracts. The sample is decomposed by papain and neutral protease to release bound arsenic, and gradient ultrasonication combined with temperature control is used to further disrupt the sample structure, thereby improving the arsenic dissolution efficiency.

[0026] Further, the auxiliary extraction solution in step (1) includes the following components: 0.05-0.1wt% EDTA, 0.1-0.3wt% citric acid, 0.03-0.05wt% zinc sulfate, and the balance is water.

[0027] Further, the gradient ultrasound conditions in step (1) are as follows: first stage: 100W ultrasound for 5 minutes; second stage: 120W ultrasound for 5 minutes, with the water bath temperature controlled at 25-30℃ during the ultrasound process, and the room left to stand for 10-20 minutes after the ultrasound is completed.

[0028] This invention uses EDTA and citric acid to complex metal ions, preventing arsenic from binding to the sample matrix. Citric acid can promote the desorption of arsenic from adsorption sites in the sample matrix by lowering the pH of the solution. Zinc sulfate adjusts the ionic strength and reduces the fixation effect of other ions on arsenic. Through synergistic effects, the accuracy of the method is improved.

[0029] Furthermore, a 0.22 μm filter membrane is used for filtration in step (1).

[0030] Further, in step (2), metal standard solutions of 0, 0.2, 1, 2, 5, 10, 20, and 50 µg / L are freshly prepared using metal standard working solution. Before making up to volume, 10 mL of 50 μg / L rhodium solution is added as an internal standard element, and a standard working curve is plotted. The above series of standard solutions are injected into the ICP-MS instrument, and the metal content is determined using the online internal standard method to obtain the standard working curve.

[0031] Furthermore, the testing conditions for the ICP-MS instrument are as follows:

[0032] High-frequency power 1.40kW;

[0033] Plasma gas flow rate: 13.0 L / min -1 ;

[0034] Carrier gas flow rate: 0.8 L / min -1 ;

[0035] He flow rate 4.0 mL / min -1 ;

[0036] Sample lift volume: 0.1 mL / min -1 ;

[0037] Sampling depth 10.0 mm;

[0038] Sampling nickel cone: orifice diameter 1.0 mm;

[0039] Cut the nickel cone: the diameter of the orifice plate is 0.4 mm.

[0040] Compared with the prior art, the advantages and beneficial effects of the present invention are as follows:

[0041] 1. This invention uses ICP-MS technology to detect trace amounts of arsenic in food additives, meeting stringent food safety standards and ensuring accurate quantification of arsenic in complex samples. The use of ICP-MS reduces testing time and labor costs; the accurate detection data supports product quality claims, enhancing consumer trust, facilitating brand differentiation, and helping companies achieve controllable arsenic contamination risks, optimized testing costs, and improved market competitiveness, providing technical support for food safety management and brand building.

[0042] 2. This invention employs a synergistic extraction process involving enzymatic hydrolysis, auxiliary extract, and ultrasound. Papain and neutral protease decompose the sample, releasing bound arsenic. Gradient ultrasound combined with temperature control further disrupts the sample structure, enhancing arsenic dissolution efficiency. This invention utilizes EDTA and citric acid to complex metal ions, preventing arsenic from binding to the sample matrix. Citric acid lowers the pH of the solution, promoting arsenic desorption from adsorption sites in the sample matrix. Zinc sulfate regulates ionic strength and reduces the immobilization effect of other ions on arsenic, synergistically improving the accuracy of the method.

[0043] 3. Compound meat product thickeners are widely used in food processing and are directly related to consumer health and safety. Compound meat product thickeners are typically composed of various natural polysaccharides and other auxiliary ingredients, which may bind to or adsorb arsenic, increasing the difficulty of extraction. This invention, by detecting arsenic content, can ensure the safety of food additives and protect public health. Attached Figure Description

[0044] Figure 1 This is a schematic diagram of a commercially available compound meat product thickener. Detailed Implementation

[0045] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0046] All raw materials used in the following embodiments of the present invention are commercially available products:

[0047] Neutral protease, enzyme activity 100u / mg; Shanghai Yuanye Biotechnology Co., Ltd. Papain, enzyme activity 800u / mg; Shanghai Yuanye Biotechnology Co., Ltd. Bromelain, enzyme activity 1200u / mg; Shanghai Yuanye Biotechnology Co., Ltd. Fig protease, enzyme activity 100u / mg; Shanghai Yuanye Biotechnology Co., Ltd. Water: Ultrapure water. Example

[0048] This embodiment provides a method for detecting the heavy metal content in food additives, including the following steps:

[0049] (1) Sample pretreatment:

[0050] A: Weigh 5g of food additive, accurate to 0.0001g, add 100mL of water, add papain and neutral protease, hydrolyze at 36℃ for 4.5h, inactivate enzymes in a boiling water bath for 10 minutes, add 250mL of auxiliary extraction solution, mix well, and then perform gradient sonication. After the process is complete, centrifuge for 10min, take the supernatant, filter it using a filter membrane, wash the filtrate with water into a 500mL volumetric flask, add 10mL of 50μg / L rhodium solution as an internal standard element, dilute to the mark of the volumetric flask with water, shake well, and use as the sample solution.

[0051] B: Add papain and neutral protease to 100mL of water, heat at 36℃ for 4.5h, inactivate enzymes in a boiling water bath for 10 minutes, add 250mL of auxiliary extraction solution, then add 10mL of 50μg / L rhodium solution as internal standard element, dilute to the mark of a 500mL volumetric flask with water, shake well, and use as blank solution.

[0052] In step (1), the amount of papain and neutral protease used is 0.5 wt% of the food additive.

[0053] The auxiliary extraction solution in step (1) includes the following components: 0.08wt% EDTA, 0.2wt% citric acid, 0.04wt% zinc sulfate, and the remainder is water.

[0054] The gradient ultrasound conditions in step (1) are as follows: first stage: 100W ultrasound for 5 minutes; second stage: 120W ultrasound for 5 minutes; the water bath temperature is controlled at 27℃ during the ultrasound process, and the water bath is left to stand for 15 minutes after the ultrasound is completed.

[0055] The step (1) uses a 0.22 μm filter membrane for filtration.

[0056] (2) Prepare fresh arsenic standard solutions of 0, 0.2, 1, 2, 5, 10, 20 and 50 µg / L using arsenic standard working solution. Before making up to volume, add 10 mL of 50 μg / L rhodium solution as an internal standard element and plot the standard working curve. Inject the above series of standard solutions into the ICP-MS instrument and use the online internal standard method to determine the arsenic content to obtain the standard working curve.

[0057] (3) The net strength of the sample solution and blank solution was tested using an ICP-MS instrument. Combined with the standard working curve, the concentration of heavy metals in the food additive was obtained, and the content of heavy metals in the food additive was further obtained.

[0058] The testing conditions for the ICP-MS instrument are as follows:

[0059] High-frequency power 1.40kW;

[0060] Plasma gas flow rate: 13.0 L / min -1 ;

[0061] Carrier gas flow rate: 0.8 L / min -1 ;

[0062] He flow rate 4.0 mL / min -1 ;

[0063] Sample lift volume: 0.1 mL / min -1 ;

[0064] Sampling depth 10.0 mm;

[0065] Sampling nickel cone: orifice diameter 1.0 mm;

[0066] Cut the nickel cone: the diameter of the orifice plate is 0.4 mm.

[0067] Comparative Example 1

[0068] The difference between this comparative example and Example 1 is that it follows the method described in the article "Simultaneous Detection of Common Food Additives and Heavy Metals in Food by Reversed-Phase HPLC-ICP-MS" (Yan Tingzhao, et al.):

[0069] Add 5g of food additive to 2mL of zinc sulfate and 2mL of potassium ferrous hydride, mix well with 50mL of water, sonicate for 20min, centrifuge for 10min, take the supernatant, filter through a 0.22μm membrane, wash the filtrate with water into a 500mL volumetric flask, add 10mL of 50μg / L rhodium solution as an internal standard element, dilute to the mark of the volumetric flask with water, shake well, and use as the sample solution.

[0070] Add 2 mL of zinc sulfate and 2 mL of potassium ferrohydride to 100 mL of water, then add 10 mL of a 50 μg / L rhodium solution as an internal standard. Dilute to the mark of a 500 mL volumetric flask with water, shake well, and use as a blank solution.

[0071] Comparative Example 2

[0072] The difference between this comparative example and Example 1 is that no enzymatic hydrolysis was performed.

[0073] (1) Sample pretreatment:

[0074] A: Weigh 5g of food additive, accurate to 0.0001g, add 250mL of auxiliary extraction solution, mix well, and then perform gradient ultrasonic treatment. After the treatment, centrifuge for 10min, take the supernatant, filter it using a filter membrane, wash the filtrate with water into a 500mL volumetric flask, add 10mL of 50μg / L rhodium solution as an internal standard element, dilute to the mark of the volumetric flask with water, shake well, and use it as the sample solution.

[0075] B: Add 250 mL of auxiliary extraction solution to 100 mL of water, then add 10 mL of 50 μg / L rhodium solution as an internal standard element, and dilute with water to the mark of a 500 mL volumetric flask. Shake well to obtain a blank solution.

[0076] Comparative Example 3

[0077] The difference between this comparative example and Example 1 is that gradient ultrasound was not used. Instead, 120W ultrasound for 10 minutes was used.

[0078] Comparative Example 4

[0079] The difference between this comparative example and Example 1 is that the ultrasound time in the second stage is different.

[0080] The gradient ultrasound conditions in step (1) are as follows: first stage: 100W ultrasound for 10 minutes; second stage: 120W ultrasound for 10 minutes, with the water bath temperature controlled at 27°C during the ultrasound process, and the room left to stand for 15 minutes after the ultrasound is completed.

[0081] Comparative Example 5

[0082] This comparative example uses the method described in the embodiment of a method for determining the heavy metal arsenic in compound food additives disclosed in Chinese Patent CN104198417B.

[0083] Comparative Example 6

[0084] This comparative example adopts the first method of hydride atomic fluorescence spectrometry in GB / T5009.11-2024.

[0085] Comparative Example 7

[0086] The difference between this comparative example and Example 1 is that the neutral protease was replaced with bromelain; and the papain was replaced with fig protease.

[0087] Performance testing

[0088] Commercially available compound meat product thickeners were tested using the detection methods described in Example 1 and Comparative Examples 1-6. Figure 1 Arsenic in ).

[0089] Table 1. Arsenic content detection results (n=3)

[0090] test Average value μg / L Standard deviation Example 1 0.028 0.0021 Example 2 0.027 0.0020 Comparative Example 1 0.019 0.0023 Comparative Example 2 0.021 0.0053 Comparative Example 3 0.023 0.0037 Comparative Example 4 0.024 0.0032 Comparative Example 5 0.027 0.0024 Comparative Example 6 0.028 0.0028 Comparative Example 7 0.022 0.0042

[0091] As shown in Table 1, the experimental data of Example 1 and Comparative Examples 5 and 6 are similar, indicating that the experimental results of this method are accurate and the data are reliable.

[0092] The detection result was smaller than expected when the pretreatment method in Comparative Example 1 was used, indicating that the above pretreatment method could not fully extract arsenic from food additives, and the relative standard deviation increased.

[0093] Comparative Example 2, which did not undergo enzymatic hydrolysis, showed a lower detection result, indicating that the above pretreatment method could not fully extract arsenic from food additives. Simultaneously, the increased standard deviation suggests that the lack of enzymatic hydrolysis resulted in poor stability of the pretreatment process.

[0094] The different ultrasonic treatment conditions in Comparative Examples 3 and 4 demonstrate that only under the ultrasonic conditions of this invention can the arsenic in the food additive be fully dissolved.

[0095] Comparative Example 7, which used different types of enzymes for pretreatment, showed lower detection results, indicating that only specific types of enzymes can yield accurate results. Simultaneously, the standard deviation increased, suggesting that only enzymatic hydrolysis using specific enzymes can ensure the full release of the target element.

[0096] The above description represents the preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for detecting the arsenic content in a compound meat product thickener, characterized in that, Includes the following steps: (1) Sample pretreatment: A: Weigh the compound meat product thickener, add water, add papain and neutral protease, hydrolyze, inactivate the enzyme, continue to add auxiliary extraction solution, mix evenly, perform gradient sonication, centrifuge after completion, take the supernatant, filter with a filter membrane, wash the filtrate with water into a volumetric flask, add rhodium solution as an internal standard element, dilute with water to the mark of the volumetric flask, shake well, and use as the sample solution; B: Add papain and neutral protease to water, heat to inactivate enzymes, continue to add auxiliary extraction solution, then add rhodium solution as internal standard element, dilute to the mark of volumetric flask with water, shake well, and use as blank solution; (2) Prepare a series of heavy metal standard solutions of different concentrations, test the net strength using an ICP-MS instrument, and obtain a standard working curve; (3) The net strength of the sample solution and blank solution was tested using an ICP-MS instrument. Combined with the standard working curve, the concentration of heavy metals in the food additives was obtained, and the content of heavy metal arsenic in the compound meat product thickener was further obtained. The auxiliary extraction solution in step (1) includes the following components: 0.05-0.1 wt% EDTA, 0.1-0.3 wt% citric acid, 0.03-0.05 wt% zinc sulfate, with the remainder being water; The gradient ultrasound conditions in step (1) are as follows: first stage: 100W ultrasound for 5 minutes; second stage: 120W ultrasound for 5 minutes. During the ultrasound process, the water bath temperature is controlled at 25-30℃. After the ultrasound is completed, the room is left to stand for 10-20 minutes.

2. The method for detecting heavy metal content in food additives according to claim 1, characterized in that, In step (1), the amount of papain and neutral protease used is 0.5-1 wt% of the food additive.

3. The method for detecting heavy metal content in food additives according to claim 1, characterized in that, In step (1), a 0.22 μm filter membrane is used for filtration.

4. The method for detecting heavy metal content in food additives according to claim 1, characterized in that, In step (2), metal standard solutions of 0, 0.2, 1, 2, 5, 10, 20, and 50 µg / L are freshly prepared using metal standard working solution. Before making up to volume, 10 mL of 50 μg / L rhodium solution is added as an internal standard element to plot a standard working curve. The metal standard solutions of the above series of concentrations are injected into the ICP-MS instrument, and the metal content is determined by the online internal standard method to obtain the standard working curve.

5. The method for detecting heavy metal content in food additives according to claim 1, characterized in that, The testing conditions for the ICP-MS instrument are as follows: High-frequency power 1.40kW; Plasma gas flow rate: 13.0 L / min -1 ; Carrier gas flow rate: 0.8 L / min -1 ; He flow rate 4.0 mL / min -1 ; Sample lift volume: 0.1 mL / min -1 ; Sampling depth 10.0 mm; Sampling nickel cone: orifice diameter 1.0 mm; Cut the nickel cone: orifice diameter 0.4mm.

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