CN111103376A

CN111103376A - Detection method of food additive

Info

Publication number: CN111103376A
Application number: CN201911403322.XA
Authority: CN
Inventors: 蒋剑
Original assignee: Grg Metrology & Test Chengdu Co ltd; Guangzhou GRG Metrology and Test Co Ltd
Current assignee: Grg Metrology & Test Chengdu Co ltd; Radio And Tv Measurement And Testing Group Co ltd
Priority date: 2019-12-30
Filing date: 2019-12-30
Publication date: 2020-05-05
Anticipated expiration: 2039-12-30
Also published as: CN111103376B

Abstract

The invention discloses a detection method of a food additive, which comprises the following steps: selecting a detection sample; step two, crushing and mixing treatment; step three, ethanol treatment; step four, ammonia water treatment; preparing a sample solution; step six, preparing a contrast solution; and step seven, detection. According to the invention, the sample is treated by adding ethanol and ammonia water step by step, so that the components can be ensured to react fully, and the purity of the supernatant obtained after solid-liquid separation of the sample is improved; the adopted sample liquid treatment mode can prevent the loss of effective components, and the adoption of the solid-liquid separation mode for two times can further improve the acquisition precision of the additive, thereby improving the detection effect of the food additive; moreover, the detection method adopted by the invention is simple to operate, can improve the detection precision, can realize field detection, and improves the detection efficiency.

Description

Detection method of food additive

Technical Field

The invention relates to a detection method, in particular to a detection method of a food additive.

Background

With the development of China, packaged food in the existing market is widely popularized, in order to prolong the shelf life of the packaged food and improve the quality of the food such as color, aroma, taste and the like, a proper amount of food additive is often required to be added into the food in the market, the food additive is often synthesized by chemical substances, and the using amount of the food additive needs to be strictly controlled during use, so that the content of the food additive is often required to be detected.

The main methods for the content of the food additive at present comprise: the method comprises the following steps of high performance liquid chromatography, thin layer chromatography, spectrophotometry and the like, wherein the high performance liquid chromatography is the most commonly used method, a single-wavelength gradient elution ultraviolet detection mode is used for separation detection, but the detection method is relatively complex in operation, general in detection precision and not suitable for large-batch sample detection, crushing equipment for food in detection is relatively traditional, uniform crushing of the food cannot be guaranteed, and efficiency and precision of later detection are affected. The thin-layer chromatography is an off-line measurement technology, an operation system is relatively open, a plurality of factors affect quantitative repeatability, reproducibility and accuracy, meanwhile, the mobile phase spreading distance is limited, and the separation capability is limited to a certain extent. Due to the complex ingredients in food, an object to be measured is often a complex multi-component complex system, interference exists between a background and a component to be measured, and absorption spectra are seriously overlapped, so that the simultaneous quantification of the background and the component to be measured is difficult by a spectrophotometry method.

Disclosure of Invention

Based on this, the invention aims to overcome the defects of the prior art and establish a detection method of the food additive.

In order to achieve the purpose, the technical scheme adopted by the invention is as follows:

a detection method of food additives comprises the following steps:

(1) selecting a solid sample to be detected;

(2) crushing and mixing the solid sample and petroleum ether into a slurry mixture by a crushing mixer;

(3) adding an ethanol solution into the slurry mixture obtained in the step (2), stirring and mixing, and performing solid-liquid separation on the mixed mixture; separating to obtain a first supernatant and a first precipitate;

(4) adding ammonia water into the first precipitate obtained in the step (3), stirring and mixing, and performing solid-liquid separation on the mixed mixture; separating to obtain a second supernatant and a second precipitate;

(5) mixing the first supernatant obtained in the step (3) and the second supernatant obtained in the step (4) to obtain a mixed solution, and adding a potassium ferrocyanide solution into the mixed solution for mixing and concentrating; after mixing, adding a proper amount of water into the solution until the pH value of the solution is adjusted to 7, and filtering the solution with the pH value of 7 through a microporous filter membrane to obtain a sample solution;

(6) preparing a standard food additive solution by taking a standard food additive;

(7) and (4) respectively adding the sample solution obtained in the step (5) and the standard solution obtained in the step (6) into a liquid chromatograph, and carrying out detection analysis.

According to the detection method, the sample is treated by adding the ethanol and the ammonia water step by step, so that the components are fully reacted, the purity of the supernatant after solid-liquid separation of the sample is improved, the loss of the components is effectively prevented by adopting a sample liquid treatment mode, and the detection efficiency is improved.

Preferably, the crushing mixer in the step (2) comprises a crushing mixer main body, one side of the crushing mixer main body is connected with a feed hopper in a through manner, and one side of the top end of the crushing mixer main body is connected with a liquid inlet hopper in a through manner;

a motor is fixed at the center of the outer wall of the top end of the crushing mixer main body, one end of an output shaft of the motor is connected with a stirring shaft, and the other end of the stirring shaft extends into the crushing mixer main body; one end of the stirring shaft extending into the crushing mixer main body is provided with a stirring paddle; crushing cutters are arranged on the outer walls of the two sides of the stirring shaft below the stirring paddle;

the bottom end of the crushing mixer main body is connected with a discharging pipe in a through mode, a mounting frame is fixed on the outer wall of the top end of the discharging pipe, and a gear box is arranged on the outer wall of the top end of the mounting frame;

the bottom of (mixing) shaft runs through in the inside of gear box and the first bevel gear of fixedly connected with, the both sides of first bevel gear are provided with the second bevel gear, one side outer wall department of second bevel gear is equipped with the axis of rotation, the one end of axis of rotation runs through in gear box and fixedly connected with stirring board.

Preferably, valves are arranged on the outer walls of the liquid inlet funnel and one side of the discharge pipe; and bearings are arranged at the rotating joints of the stirring shaft, the rotating shaft and the mounting rack.

Carry out broken making beating to the solid-state sample of food through novel broken blendor, the pulpiness mixture that realizes the later stage and obtain is more even, has improved the precision and the efficiency that the later stage detected. The device can process a sample for about 10min, and is suitable for large-scale sampling. Experiments prove that the standard recovery rate of the sample treated by the device is superior to the requirement of GB-T27404-2008.

Preferably, in the step (2), the inside of the crushing and mixing machine is firstly cleaned and disinfected at high temperature by steam.

Preferably, the weight ratio of the solid sample to petroleum ether is 3: 1.

preferably, in the step (3), the volume ratio of the slurry mixture to the ethanol solution is 4: 1.

Preferably, in the step (4), the volume ratio of the first precipitate to the ammonia water is 3: 1. Preferably, the solid-liquid separation in the step (3) and the step (4) is carried out in a centrifuge, the working centrifugal rate of the centrifuge is 4000-7000 r/min, and the centrifugal time is 25-45 s.

Preferably, in the step (5), the pore diameter of the microporous filter membrane is 0.2-0.3 micron. The filter membrane can remove large particulate matters in a sample at a good rate.

Compared with the prior art, the invention has the beneficial effects that:

according to the method for detecting the content of the food additive, the sample is treated by adding the ethanol and the ammonia water step by step, so that the components can be ensured to react fully, and the purity of the supernatant obtained after solid-liquid separation of the sample is improved; the adopted sample liquid treatment mode can prevent the loss of effective components, and the adoption of the solid-liquid separation mode for two times can further improve the acquisition precision of the additive, thereby improving the detection effect of the food additive; moreover, the detection method adopted by the invention is simple to operate, can improve the detection precision, can realize field detection, and improves the detection efficiency.

Drawings

FIG. 1 is a flow chart of a detection method according to an embodiment of the present invention;

FIG. 2 is a front sectional structure view of the novel crushing mixer of the invention;

FIG. 3 is an enlarged view of area A of FIG. 2 in accordance with the present invention;

FIG. 4 is a top view sectional structure diagram of the novel crushing mixer of the present invention;

FIG. 5 is a detection chromatogram of various additives of the present invention;

FIG. 6 is a chromatogram for the detection of a plurality of single species according to the invention;

wherein, 1, crushing the mixer main body; 2. a feed hopper; 3. a liquid inlet funnel; 4. a valve; 5. a motor; 6. a stirring shaft; 7. a stirring paddle; 8. a crushing knife; 9. a gear case; 10. a first bevel gear; 11. a second bevel gear; 12. a rotating shaft; 13. a stirring plate; 14. a mounting frame; 15. and (4) discharging the pipe.

Detailed Description

To better illustrate the objects, aspects and advantages of the present invention, the present invention will be further described with reference to the accompanying drawings and specific embodiments.

The technical route and the process flow of the specific detection method of the embodiment are shown in the attached figure 1, and the specific detection process is as follows:

selecting a detection sample; step two, crushing and mixing treatment; step three, ethanol treatment; step four, ammonia water treatment; preparing a sample solution; step six, preparing a contrast solution; step seven, detection;

in the first step, taking the food to be detected, and selecting a solid sample to be detected on the food according to an averaging method;

in step two, get novel broken blendor, carry out high temperature sterilization to the inside of novel broken blendor through steam earlier, add the solid-state sample who chooses in step one in broken blendor, again in inside the appropriate amount petroleum ether that adds of broken blendor, and the mass ratio of solid-state sample and petroleum ether is 3:1, crushing and mixing a solid sample and petroleum ether in the mixer into a slurry mixture through the operation of a crushing mixer;

the structure of the novel crushing mixer in the second step is shown as the attached figures 2-4: comprises a crushing mixer main body 1, a feeding funnel 2, a liquid inlet funnel 3, a valve 4, a motor 5, a stirring shaft 6, a stirring paddle 7, a crushing cutter 8, a gear box 9, a first bevel gear 10, a second bevel gear 11, a rotating shaft 12, a stirring plate 13, a mounting rack 14 and a discharging pipe 15, wherein the feeding funnel 2 is arranged on the outer wall of the top end of one side of the crushing mixer main body 1 in a through way, the liquid inlet funnel 3 is connected on the outer wall of one side of the top end of the crushing mixer main body 1 in a through way, the motor 5 is fixed at the center of the outer wall of the top end of the crushing mixer main body 1 by a bolt, the stirring shaft 6 is fixedly connected at one end of an output shaft of the motor 5, one end of the stirring shaft 6 penetrates through the inside of the crushing mixer main body 1, the stirring paddle 7 is fixedly connected on the outer wall of one side of the top end of the stirring, a mounting frame 14 is fixedly welded on the outer wall of the top end of the discharge pipe 15, a gear box 9 is fixedly mounted on the outer wall of the top end of the mounting frame 14, a first bevel gear 10 is fixedly connected to the bottom end of the stirring shaft 6, which penetrates through the gear box 9, two second bevel gears 11 are arranged on two sides of the first bevel gear 10 inside the gear box 9, a rotating shaft 12 is fixedly welded in the outer wall of one side of each second bevel gear 11, and a stirring plate 13 is fixedly connected to one end of each rotating shaft 12, which penetrates through the outer wall of the gear; all be provided with valve 4 on the outer wall of one side of feed liquor funnel 3 and discharging pipe 15, (mixing) shaft 6 and axis of rotation 12 all are provided with the bearing with mounting bracket 14 rotation junction. The novel crushing mixer is used for crushing and pulping solid samples of food, so that a slurry mixture obtained in the later period is more uniform, the accuracy of later-period detection is improved, and the efficiency of later-period detection is improved;

in the third step, adding the ethanol solution into the slurry mixture in the second step, stirring and mixing, adding the mixed mixture into a centrifugal machine, and performing solid-liquid separation through the centrifugal machine; separating to obtain a first supernatant and a first precipitate; the volume ratio of the slurry mixture to the ethanol solution added in the third step is 4: 1;

in the fourth step, ammonia water is added into the first precipitate obtained in the third step, stirring and mixing are carried out, the mixed mixture is added into a centrifuge, and solid-liquid separation is carried out through the centrifuge; separating to obtain a second supernatant and a second precipitate; the volume ratio of the first precipitate to the ammonia water added in the fourth step is 3: 1; the working centrifugal rate of the centrifugal machine in the third step and the fourth step is 4000-7000 revolutions per minute, and the centrifugal time is 25-45 s;

in the fifth step, mixing the first supernatant obtained in the third step and the second supernatant obtained in the fourth step to obtain a mixed solution, and adding a potassium ferrocyanide solution into the mixed solution for mixing and concentrating; after mixing, adding a proper amount of water into the solution until the pH value of the solution is adjusted to 7, and filtering the solution with the pH value of 7 through a microporous filter membrane to obtain a sample solution; in the fifth step, the aperture of the microporous filter membrane is 0.2-0.3 micron;

in the sixth step, taking the standard substance of the food additive, and preparing a food additive standard substance solution with accurate concentration;

in the seventh step, the sample solution obtained in the fifth step and the standard solution obtained in the sixth step are respectively added into a liquid chromatograph, and detection is carried out by adopting gradient elution and variable wavelength; the specific process is as follows:

weighing 2g (accurate to 0.001g) of sample, placing in a 50ml centrifuge tube, 0.5ml, 1.25ml and 2.25ml of dehydroacetic acid standard solution with the concentration of 1mg/ml, adding about 10ml of water, adjusting the pH to 7.5 by using sodium hydroxide solution, transferring to a 50ml volumetric flask, adding water to dilute to the scale, and shaking up. Placing in a centrifuge tube, and centrifuging at 4000r/min for 10 min. 20ml of the supernatant was adjusted to pH 5 with 10% formic acid solution to a volume of 25 ml. 5ml of the activated solid phase extraction column is taken, 5ml of water is used for leaching, 2ml of 70% methanol solution is used for eluting, and 2ml of eluent is collected. Mixing by vortex, filtering with 0.45 μm organic filter membrane, and performing chromatographic determination; specific results are shown in table 1, and specific detection chromatograms are shown in fig. 5-6:

TABLE 1

FIG. 5 is a graph of various additives, and it can be seen that the separation effect of various additives is good after the extraction by the method, each substance has good response, and a good separation effect is achieved. FIG. 6 is a graph of a single substance, and FIG. 5 compares the response of multiple substances to the single substance response of FIG. 6.

In order to achieve a better detection effect by the detection method, specific parameters of the method are optimally selected, and when the weight ratio of the solid sample to the petroleum ether is different, the recovery rate is shown in table 2; when the volume ratio of the slurry mixture to the ethanol solution was different, the recovery rate was as shown in Table 3; when the volume ratio of the first precipitate to the aqueous ammonia was different, the recovery rate was as shown in table 4:

TABLE 2

Solid sample/Petroleum Ether	Recovery rate
		1:1	65.5％
2:1	71.3％
		3:1	86.9％
4:1	78.4％

TABLE 3

Slurry mixture/ethanol solution	Recovery rate
		2:1	68.9％
3:1	77.1％
		4:1	88.4％
5:1	75.4％

TABLE 4

First precipitate/Ammonia	Recovery rate
		1:1	72.9％
2:1	78.6％
		3:1	90.1％
4:1	80.4％

As can be seen from table 2, when the weight ratio of the solid sample to petroleum ether was 3:1, the recovery rate is optimal; as can be seen from Table 3, the recovery rate was optimum when the volume ratio of the slurry mixture to the ethanol solution was 4: 1; as can be seen from table 4, the recovery rate was optimum when the volume ratio of the first precipitate to the aqueous ammonia was 3: 1.

Finally, it should be noted that the above embodiments are only used for illustrating the technical solutions of the present invention and not for limiting the protection scope of the present invention, and although the present invention is described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that modifications or equivalent substitutions can be made on the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention.

Claims

1. A detection method of food additives is characterized by comprising the following steps:

(1) selecting a solid sample to be detected;

2. The method for detecting food additives according to claim 1, wherein the crushing mixer in the step (2) comprises a crushing mixer body, a feeding funnel is connected to one side of the crushing mixer body in a penetrating manner, and a feeding funnel is connected to one side of the top end of the crushing mixer body in a penetrating manner;

3. The method for detecting food additives according to claim 2, wherein valves are disposed on the outer walls of the liquid inlet funnel and the liquid outlet pipe; and bearings are arranged at the rotating joints of the stirring shaft, the rotating shaft and the mounting rack.

4. The method for detecting food additive according to claim 1, wherein in the step (2), the inside of the crushing and mixing machine is first cleaned and sterilized at high temperature by steam.

5. The method for detecting a food additive according to claim 1, wherein the weight ratio of the solid sample to the petroleum ether is 3: 1.

6. the method for detecting a food additive according to claim 1, wherein in the step (3), the volume ratio of the slurry mixture to the ethanol solution is 4: 1.

7. The method for detecting a food additive according to claim 1, wherein in the step (4), the volume ratio of the first precipitate to the ammonia water is 3: 1.

8. The method for detecting the food additive according to claim 1, wherein the solid-liquid separation in the step (3) and the step (4) is performed in a centrifuge, the operating centrifugal rate of the centrifuge is 4000-7000 rpm, and the centrifugal time is 25-45 s.

9. The method for detecting food additive according to claim 1, wherein in the step (5), the pore size of the microporous filter membrane is 0.2 to 0.3 μm.