A method and device for rapid on-site detection of VC content in non-red vegetables

Abstract

The present invention is a method and device for rapid on-site detection of VC content in non-red vegetables, comprising the following steps: S1, chopping and juicing the vegetable sample, taking a quantitative amount of juicing; S2, measuring the volume of the vegetable juice, recording V; S3, taking 1ml of the vegetable juice, adding oxalic acid to the volume of 10ml, soaking for 10-15min, this is the test solution; S4, taking 2ml of pure water and titrating with dichloroindophenol, recording the number of drops consumed; S5, taking 1ml of ascorbic acid standard solution in a test tube, adding oxalic acid to the volume of 10ml, titrating, recording the number of drops consumed and the titer T; S6, taking 2ml of the test solution, titrating with 2,6-dichloroindophenol solution, recording the number of drops, and converting it into the number of drops per milliliter; S7, substituting the formula to calculate the result. The method and supporting device of the present invention are used for rapid determination of quality analysis in non-red vegetable production areas, which is simple and easy, has low analysis cost, has little environmental pollution, and has strong popularization and application.

Description

Technical Field

[0001] The invention relates to the technical field of vitamin C content detection, and in particular to an on-site rapid detection method and device for the VC content of non-red vegetables. Background Art

[0002] Vitamin C (VC) is a water-soluble vitamin that has an anti-scurvy effect. It is also known as ascorbic acid. The aqueous solution of vitamin C is weakly acidic. Its chemical nature is a type of hexuronic acid with strong reducing properties. Vitamin C cannot be synthesized in the human body and must be taken from food. The consumption of fruits and vegetables is an important source of vitamin C for the human body. It is also an important medical and pharmacological substance and one of the main indicators for evaluating the nutritional value of fruits, vegetables and fruit and vegetable drinks. Vitamin C is extremely unstable and is easily oxidized by oxygen in the air and destroyed by alkali, heavy metals and high temperature. The VC content of different vegetables varies greatly. Since the changes of vitamin C during the storage and processing of fruits and vegetables have an important impact on people's health, the detection and analysis of vitamin C has gradually occupied an important position in food nutrition analysis. It is of great significance to people's dietary health and food preservation.

[0003] The methods for determining the content of vitamin C include spectroscopy (fluorescence photometry, ultraviolet spectrophotometry, visible spectrophotometry, atomic absorption spectrophotometry, polarimetry, refractometry, etc.), titration (iodine titration, acid-base titration, dichlorophenol indophenol titration), chromatography (high performance liquid chromatography, ion exchange chromatography, capillary electrophoresis, etc.), electrochemical method (coulometry, square wave polarography, cyclic voltammetry, etc.), and the determination of VC content also includes spectroscopy such as hydrogen nuclear magnetic resonance and flow injection spectrophotometry, chromatography such as reverse chromatography and ultra-high performance liquid chromatography, near-infrared diffuse reflectance technology and chemometric methods, laser Raman spectroscopy, etc. The titration method is the most complete and does not require special instruments, and the cost is low, but the operation is relatively troublesome and the accuracy is not very ideal. The electrochemical method is greatly disturbed by current, ions, and air, requires special instruments, and the instrument preheating time is long, it cannot be detected continuously, and the operation requirements are high. Chromatography is highly efficient and sensitive, can quickly process multiple samples for testing, and can perform continuous testing, but requires special instruments and is expensive. Spectroscopy is low-cost and has simpler instruments, but is greatly affected by the state of the sample and has large errors. These methods cannot meet the requirements of easy promotion and rapid on-site testing. Summary of the invention

[0004] The present invention provides an on-site rapid detection method for the VC content of non-red vegetables, which is used for rapid quality analysis at the production site of non-red vegetables. The method is simple and easy to operate, has low analysis cost, low requirements on personnel operation, and the reagents used have little pollution to the environment. The instruments used are conventional and simple instruments, and the method has strong popularization and applicability.

[0005] The above technical objectives of the present invention are achieved through the following technical solutions:

[0006] A method for rapid on-site detection of VC content in non-red vegetables comprises the following steps:

[0007] S1. Chop the vegetable sample and squeeze the juice, then take a certain amount of the juice and put it into a test tube;

[0008] S2. Measure the volume of vegetable juice using a graduated test tube and record V (ml);

[0009] S3. Use a pipette to transfer 1 ml of vegetable juice, dilute to 10 ml with oxalic acid, and extract for 10-15 minutes. This is the test solution.

[0010] S4. Take 2 ml of pure water (or mineral water) and titrate with dichloroindophenol, and record the number of drops consumed (blank volume V2);

[0011] S5. Determine T value;

[0012] Take 1 ml of ascorbic acid standard solution in a test tube, make up to 10 ml with oxalic acid, take 2 ml for titration, and record the number of drops consumed (control volume V1)

[0013]

[0014] (V1 or )

[0015] It is normal when 0.081≤T≤0.09, otherwise the 2,6-dichloroindophenol solution needs to be re-prepared;

[0016] S6. Take 2 ml of the test solution and titrate it with 2,6-dichloroindophenol solution, record the number of drops and convert it into drops per ml (C);

[0017] S7. Results

[0018]

[0019] x—L(+)-ascorbic acid content in the sample, in milligrams per 100 grams (mg / 100g);

[0020] The above formula is only used to calculate the VC content of vegetables with a VC content in the range of 5 to 100 mg / 100 g. The calculation result is expressed as the arithmetic mean of two independent measurement results obtained under repeatability conditions, and the result is retained to one significant figure.

[0021] Further preferably, the concentration of the oxalic acid solution in steps S3 and S5 is 2%.

[0022] Further preferably, in step S5, the concentration of the ascorbic acid standard solution is 1 mg / ml.

[0023] Further preferably, in step S1, the vegetable sample is wiped clean with a paper towel, chopped and mixed according to the quartering method, 100 g is put into a stainless steel hand-cranked juicer, and the juicer is rinsed with clean water and dried with a paper towel before use.

[0024] The present invention also discloses a device for rapid on-site detection of VC content of non-red vegetables, comprising a rectangular detection block, wherein a residual material chamber, a first liquid storage chamber, a constant volume chamber and a second liquid storage chamber are sequentially arranged from left to right in the rectangular detection block, and a detection test tube with an upper end opening is arranged on the right side of the rectangular detection block, and the bottoms of the first liquid storage chamber and the second liquid storage chamber are both higher than the bottoms of the residual material chamber, the constant volume chamber and the detection tube;

[0025] The upper end of the first liquid storage chamber is connected to the residual material chamber through a first connecting channel, the bottom of the first liquid storage chamber is connected to the constant volume chamber through a second connecting channel, the bottom of the constant volume chamber is connected to the bottom of the second liquid storage chamber through a third connecting channel, the bottom of the second liquid storage chamber is connected to the detection test tube through a fourth connecting channel, and switch valves are provided between the bottom of the first liquid storage chamber and the second connecting channel, the bottom of the constant volume chamber and the third connecting channel, the third connecting channel and the bottom of the second liquid storage chamber, and the bottom of the second liquid storage chamber and the fourth connecting channel;

[0026] The residual material chamber and the constant volume chamber are both open at the upper ends, and a socket connected to the first liquid storage chamber is provided downwardly at the upper end of the rectangular detection block, and a liquid inlet funnel is detachably connected to the socket, and a filter residue net is arranged in the liquid inlet funnel, and an adjustment hole connected to the second liquid storage chamber is provided downwardly at the upper end of the rectangular detection block, and a piston is slidably connected in the second liquid storage chamber, and a piston rod is provided upwardly on the piston, which passes through the adjustment hole and can move up and down relative to the piston, and a knob is connected to the upper end of the piston rod.

[0027] According to the above technical scheme, when the VC content of vegetables is detected on site quickly, the vegetables are first chopped and juiced, and the juice is added into the first liquid storage chamber through the liquid inlet funnel. When the juice is more than 1 ml, it flows into the residual material chamber through the first connecting channel; the switch valve of the second connecting channel is opened to allow 1 ml of the juice in the first liquid storage chamber to flow into the constant volume chamber, and 2% oxalic acid solution is added to the constant volume chamber to make the volume to 10 ml; the switch valves at both ends of the third connecting channel are opened, the switch valve of the fourth connecting channel is closed, and the piston is moved upward by the knob to absorb 2 ml of the constant volume liquid from the constant volume chamber into the second liquid storage chamber; the switch valves at both ends of the third connecting channel are closed, and the switch valve of the fourth connecting channel is opened to transfer 2 ml of the constant volume liquid into the detection test tube; the glass dropper filled with 2,6-dichloroindophenol solution is used for measurement, and the consumption of 2,6-dichloroindophenol solution divided by 2 is the volume (y) of 2,6-dichloroindophenol solution consumed per milliliter of the test liquid, and the result is finally entered into the formula for calculation.

[0028] Further preferably, each switch valve is a sliding baffle, each sliding baffle is provided with a through hole, each sliding baffle is provided with end blocks at both ends, and a plurality of sliding holes for corresponding sliding baffles to slide are provided through the rectangular detection block.

[0029] Further preferably, the adjustment hole is a threaded hole, and the piston rod is a threaded rod.

[0030] Further preferably, the volume from the first liquid storage chamber to the first connecting channel is 1 ml.

[0031] Further preferably, the rectangular detection block is made of a transparent material.

[0032] Compared with the prior art, the present invention has the following beneficial effects:

[0033] First, the 2,6-dichloroindophenol colorimetric rapid determination method standard was formulated with reference to the national standard. The main technical content is determined based on a large amount of test data and is scientific and reliable. This method is used for rapid quality analysis of non-red vegetable production areas. It is simple and easy to use, has low analysis costs, low requirements for personnel operation, and the reagents used have little environmental pollution. The instruments used are conventional and simple instruments, and have strong promotion and application.

[0034] Second, before the 2,6-dichloroindophenol is titrated for color development, oxalic acid solution is added to the test solution to place VC in a relatively acidic environment, making it less likely to be oxidized and making it easier for VC to react with 2,6-dichloroindophenol for color development;

[0035] Third, since 2,6-dichloroindophenol is unstable and easily degraded, the titer T is determined by step S4 and step S5 to compare and judge the degradation of 2,6-dichloroindophenol, so as to avoid excessive degradation of 2,6-dichloroindophenol affecting the test results. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 It is a linear relationship diagram between the concentration of the test solution and the consumption of 2,6-dichloroindophenol solution;

[0037] Figure 2 It is a schematic diagram of the overall structure of the on-site rapid detection device;

[0038] Figure 3 Used to display the internal structure of the rectangular detection block;

[0039] Figure 4 It is a schematic diagram of the overall structure of the sliding baffle.

[0040] In the figure: 1, rectangular detection block; 11, jack; 2, residual material chamber; 3, first liquid storage chamber; 4, constant volume chamber; 5, second liquid storage chamber; 51, piston; 52, piston rod; 53, knob; 6, detection test tube; 71, first connecting channel; 72, second connecting channel; 73, third connecting channel; 74, fourth connecting channel; 8, sliding baffle; 81, through hole; 82, end block; 9, liquid inlet funnel; 91, filter residue net; DETAILED DESCRIPTION

[0041] In order to make those skilled in the art better understand the technical solution of the present invention, the present invention is further described in detail below in conjunction with embodiments. It will be understood by those skilled in the art that the following embodiments are only used to illustrate the present invention and should not be regarded as limiting the scope of the present invention.

[0042] In 2020, a study on agents and methods for improving the salt-alkali stress resistance of wax gourd was carried out in the greenhouse of Kunming University Agricultural Practice Park. The wax gourd plants were treated according to the method of the present invention, and the operation was as follows:

[0043] Example 1

[0044] A method for rapid on-site detection of VC content in non-red vegetables, comprising the following steps:

[0045] S1. Wipe the vegetable sample clean with a paper towel, chop and mix according to the quartering method, take 100g and put it into a stainless steel hand-cranked juicer. Rinse the juicer with clean water and wipe it dry with a paper towel before use;

[0046] S2. Measure the volume of vegetable juice using a graduated test tube and record V (ml);

[0047] S3. Use a pipette to take 1 ml of vegetable juice, dilute it to 10 ml with 2% oxalic acid, and extract for 10-15 minutes. This is the test solution.

[0048] S4. Take 2 ml of pure water (or mineral water) and titrate with dichloroindophenol, and record the number of drops consumed (blank volume V2);

[0049] S5. Determine T value;

[0050] Take 1 ml of ascorbic acid standard solution (1 mg / ml) in a test tube, dilute to 10 ml with 2% oxalic acid, take 2 ml for titration, and record the number of drops consumed (control volume V1)

[0051]

[0052] (V1 or )

[0053] It is normal when 0.081≤T≤0.09, otherwise the 2,6-dichloroindophenol solution needs to be re-prepared.

[0054] S6. Take 2 ml of the test solution and titrate it with 2,6-dichloroindophenol solution. Record the number of drops and convert it into drops per milliliter (C). The concentration of the test solution (mg / ml) is linearly related to the consumption of 2,6-dichloroindophenol solution (ml). Figure 1 ;

[0055] S7. Results

[0056]

[0057] x—L(+)-ascorbic acid content in the sample, in milligrams per 100 grams (mg / 100g);

[0058] The above formula is only used to calculate the VC content of vegetables with a VC content in the range of 5 to 100 mg / 100 g. The calculation result is expressed as the arithmetic mean of two independent measurement results obtained under repeatability conditions, and the result is retained to one significant figure.

[0059] Example 2

[0060] A method for rapid on-site detection of VC content in non-red vegetables. The technical solutions of Example 2 and Example 1 are the same and will not be described in detail. The difference lies in that 2.5 ml of the test solution is taken in S6.

[0061] Example 3

[0062] A method for rapid on-site detection of VC content in non-red vegetables. The technical scheme of Example 3, which is the same as that of Example 1, is not described in detail. The difference lies in that 4 ml of the test solution is taken in S2.

[0063] Example 4

[0064] A method for rapid on-site detection of VC content in non-red vegetables. The technical scheme of Example 3, which is the same as that of Example 1, is not described in detail. The difference lies in that 2 ml of vegetable juice is transferred in S3 and 2 ml of test liquid is taken in S6.

[0065] Example 5

[0066] A method for rapid on-site detection of VC content in non-red vegetables. The technical scheme of Example 4, which is the same as that of Example 1, is not described in detail. The difference lies in that 2 ml of vegetable juice is transferred in S3 and 2.5 ml of the test liquid is taken in S6.

[0067] Example 6

[0068] A method for rapid on-site detection of VC content in non-red vegetables. The technical scheme of Example 5, which is the same as that of Example 1, is not described in detail. The difference lies in that 2 ml of vegetable juice is taken in S3 and 4 ml of the test liquid is taken in S6.

[0069] Compare the results of the titration method (national standard method) with those of Examples 1-6

[0070] Table 1 Results of Examples 1-6 (juice extraction method) and titration method (national standard method)

[0071]

[0072] After the sample is squeezed, 1 ml and 2 ml are taken to volume, and then 2 ml, 2.5 ml, and 4 ml are taken as the test solution, and the results of Example 1-6 (the rapid determination results of the 2,6-dichloroindophenol colorimetric method) are compared with the results of the 2,6-dichloroindophenol titration method. From Table 6, the results of taking 1 ml of juice to volume and taking 2 ml of the test solution and taking 2 ml of juice to volume and taking 2.5 ml of the test solution are close to the results of the 2,6-dichloroindophenol titration method. After correlation analysis (distance correlation) with SPSS statistical software, the correlation coefficients are all 0.999. Considering the abundance of Vc content in the test solution and the use of the result values, it is believed that both can be used for determination. From the perspective of ease of operation, squeezing 1 ml of juice to volume and taking 2 ml of the test solution is more suitable.

[0073] Oxalic acid solution concentration selection

[0074] In step S2 above, the concentrations of the oxalic acid solution added to the test tube are 0, 0.4%, 1%, 2%, 3%, and 5% in sequence. After the 2,6-dichloroindophenol solution is dripped until the color is evenly distributed and remains unfaded for 15 seconds, the number of drops dripped is recorded, and the statistical calculation results are shown in Table 2. The volumes of the standard solution and the standard concentration control solution dripped into the 2,6-dichloroindophenol solution are also recorded, as shown in Table 3.

[0075] Table 2 Effect of different oxalic acid concentrations on the Vc content of cabbage

[0076] Oxalic acid content 0 0.4％ 1％ 2％ 3％ 5％ Titration (ml) 0.20 3.80 4.70 4.35 4.25 4.25 Results (mg / 100g) 0.0123 0.4569 0.5595 0.5255 0.5095 0.4907

[0077] From Table 2, we can see that the Vc of cabbage samples extracted with different oxalic acid solution concentrations was determined by 2,6-dichloroindophenol titration method. The peak values ​​appeared at 1% and 2%. However, after multiple experiments, the difference between the repeated 1% values ​​was greater than 2%, indicating that the Vc of the sample was relatively stable when extracted with 2% oxalic acid solution.

[0078] Table 3 Effect of different oxalic acid concentrations on the titration of standard solution and standard concentration control solution

[0079]

[0080] From Table 3, it can be seen that the standard solution (10 ml of the corresponding oxalic acid concentration solution) has little effect, while the peak values ​​of the standard concentration control solution [10 ml of the corresponding oxalic acid concentration solution + 1 ml (1 mg / ml) ascorbic acid solution] appear at 1% and 2%.

[0081] Based on the results of Table 1 and Table 2, the concentration of oxalic acid solution should be 2%.

[0082] Selection of 2,6-dichloroindophenol concentration

[0083] The concentrations of the 2,6-dichloroindophenol solutions titrated in the above steps S4 and S5 are 0.1299 mg / ml, 0.0862 mg / ml and 0.0413 mg / ml, respectively. After the 2,6-dichloroindophenol solution is dripped until the color is evenly distributed and remains unfaded for 15 seconds, the number of drops dripped is recorded.

[0084] Table 4 Titration of standard solution and standard concentration control solution with different 2,6-dichloroindophenol concentrations

[0085] 2,6-Dichloroindophenol concentration (mg / ml) 0.1299 0.0862 0.0413 Standard solution titration (ml) 0.10 0.20 0.35 Standard concentration control solution titration (ml) 7.80 11.80 24.55

[0086] From Table 4, the higher the concentration of 2,6-dichloroindophenol, the smaller the titration of the standard solution, and the smaller the titration of the standard concentration control solution [10ml2% oxalic acid solution + 1ml (1mg / ml) ascorbic acid solution]. As far as this rapid detection method is concerned, the low concentration of 2,6-dichloroindophenol solution increases the amount of color reaction and lacks operability for vegetable varieties with high Vc content. Therefore, the use of medium or medium-high concentration 2,6-dichloroindophenol solution is more in line with the rapid requirements.

[0087] Recovery rate experiment

[0088] The accuracy of the method was measured by the standard addition recovery method. This method is to add different levels of known amounts of standard substances to a stable sample (the amount of the standard substance is taken as the true value) and call it the spiked sample; the sample and the spiked sample are measured at the same time; the spiked sample measurement value minus the sample measurement value divided by the added value is used to calculate the recovery rate, see Table 5 and Table 6.

[0089] Table 5 2,6-Dichloroindophenol titration method

[0090]

[0091]

[0092] Table 6 2,6-Dichloroindophenol colorimetric rapid determination method

[0093]

[0094] From the results in Tables 5 and 6, it can be seen that the recovery rates of all samples are greater than 80%, a few exceed 100%, but none exceed 120%; the relative standard deviation is less than 15%, and only a few exceed 10%, indicating that the detection results of the 2,6-dichloroindophenol colorimetric rapid determination method are scientific and credible.

[0095] Differences between samples and batches

[0096] Table 7 Vc content results of different batches of samples

[0097] sample First batch Second batch The third batch Baby cabbage 0.1762 0.3298 0.4510 Wrinkled Pepper 0.8335 1.3257 1.1085 Cabbage 0.5198 0.6530 0.4777 cucumber 0.1231 0.1989 0.0839 Green pepper 0.9164 1.8391 1.2539 Shanghai Blue \ 0.2901 0.3078 Choy Sum \ 0.6570 0.3277 Big bitter vegetable \ 0.6273 0.6921 Garlic sprouts \ 0.7353 0.5698 French beans \ 0.1798 0.1169 White radish \ 0.1592 0.1984 celery \ 0.0323 0.0184 Small melon \ 0.2263 0.2161

[0098] From Table 7, it can be seen that there are large differences between different samples of the same batch of samples, which is related to the characteristics of the vitamin C content of various vegetables. There are also differences between different batches of the same vegetable, which is related to factors such as the origin, freshness, and storage time of the vegetables. Therefore, this rapid detection method is only suitable for the determination of vitamin C content in the same origin, the same type of vegetables, the same production cycle, and the same harvest period.

[0099] Differences in Vc content of samples after storage time

[0100] Table 8 Vc content of samples from the same batch at different storage times

[0101] sample Day 0 3 days 8 days 10 days Choy Sum 0.3277 0.4945 \ \ Potato 0.2278 0.1983 0.2325 0.2272 Big bitter vegetable 0.6921 0.6484 0.7961 \ Baby cabbage 0.4510 0.4343 0.4562 0.3081 cowpea 0.2153 0.1993 0.1384 0.0821 Garlic sprouts 0.5698 0.5848 0.4581 0.4368 French beans 0.1169 0.0899 0.0998 0.0959 celery 0.0184 0.0308 \ \ Small melon 0.2161 0.2038 0.1828 0.1787 Green pepper 1.2539 1.3290 0.9949 0.8769 Wrinkled Pepper 1.1085 1.2034 1.1102 1.1832 White radish 0.1984 0.1753 0.1773 0.1708 Shanghai Blue 0.3078 0.2386 0.3783 0.4269 Cabbage 0.4777 0.5735 0.6600 0.6492 cucumber 0.0839 0.1081 0.1468 0.1377

[0102] The 2,6-dichloroindophenol titration method was used to determine the Vc content of the same vegetable after being stored for different days. From Table 8, it can be seen that the Vc content of most vegetables increased slightly first and then decreased as the number of days they were stored increased; a few vegetables could not be stored for the predetermined number of days. This shows that the storage time has an impact on the Vc content of vegetables, and non-storable vegetables can only be stored for a short period of time.

[0103] Comparison between this method and the national standard method

[0104] The on-site rapid testing method of the present invention and the national standard method were used for comparison, and white hair, cabbage and green pepper from the same origin, the same production cycle, the same harvest period and the same storage time were tested simultaneously, and the test results of the two methods were recorded. The comparison results are shown in the following table.

[0105] Table 9 Comparison with the national standard results

[0106] vegetable National standard method (mg / 100g) On-site rapid test method (mg / 100g) deviation Chinese cabbage 12.43 12.36 -0.56％ cabbage 17.12 17.39 +1.58％ Green pepper 85.28 85.62 +0.4％

[0107] As can be seen from the above table, there is no obvious difference between the on-site rapid test method and the national standard method for detecting the VC content of the three vegetables. The biggest difference is the test result of cabbage, which is only 1.58%. This shows that the on-site rapid test method of the present invention is scientific and effective, and can be widely used for on-site rapid VC content detection of vegetables.

[0108] Example 7

[0109] Reference Figure 2-4 A device for rapid on-site detection of VC content in non-red vegetables comprises a rectangular detection block 1, which is made of a transparent material. A residual material chamber 2, a first liquid storage chamber 3, a constant volume chamber 4 and a second liquid storage chamber 5 are arranged in the rectangular detection block 1 from left to right. A transparent detection test tube 6 with an open upper end is arranged on the right side of the rectangular detection block 1. The bottoms of the first liquid storage chamber 3 and the second liquid storage chamber 5 are higher than the bottoms of the residual material chamber 2, the constant volume chamber 4 and the detection tube.

[0110] The upper end of the first liquid storage chamber 3 is connected with the residual material chamber 2 through a first connecting channel 71, the volume of the first liquid storage chamber 3 to the first connecting channel 71 is 1 ml, the bottom of the first liquid storage chamber 3 is connected with the constant volume chamber 4 through a second connecting channel 72, the bottom of the constant volume chamber 4 is connected with the bottom of the second liquid storage chamber 5 through a third connecting channel 73, the bottom of the second liquid storage chamber 5 is connected with the detection test tube 6 through a fourth connecting channel 74, and a switch valve is arranged between the bottom of the first liquid storage chamber 3 and the second connecting channel 72, the bottom of the constant volume chamber 4 and the third connecting channel 73, the third connecting channel 73 and the bottom of the second liquid storage chamber 5, and the bottom of the second liquid storage chamber 5 and the fourth connecting channel 74. Each switch valve is a sliding baffle 8, and each sliding baffle 8 is provided with a through hole 81, and each sliding baffle 8 is provided with an end block 82 at both ends, and a plurality of sliding holes for corresponding sliding baffles 8 to slide are arranged through the rectangular detection block 1 (figure omitted).

[0111] The residual material chamber 2 and the constant volume chamber 4 are both open at the upper ends. The upper end of the rectangular detection block 1 is downwardly provided with a socket 11 connected to the first liquid storage chamber 3. The socket 11 is detachably connected to a liquid inlet funnel 9, and a filter residue net 91 is arranged in the liquid inlet funnel 9. The upper end of the rectangular detection block 1 is downwardly provided with an adjustment hole (not shown) connected to the second liquid storage chamber 5. A piston 51 is slidably connected in the second liquid storage chamber 5. The piston 51 is upwardly provided with a piston rod 52 that passes through the adjustment hole and can move up and down relative to the piston 51. The adjustment hole is a threaded hole, and the piston rod 52 is a threaded rod. The upper end of the piston rod 52 is connected to a knob 53.

[0112] Usage: When conducting a rapid on-site test of the VC content of vegetables, first chop the vegetables and squeeze out the juice, and add the squeezed juice into the first liquid storage chamber 3 through the liquid inlet funnel 9. When the squeezed juice exceeds 1 ml, it flows into the residual material chamber 2 through the first connecting channel 71; open the switch valve of the second connecting channel 72 to allow 1 ml of the squeezed juice in the first liquid storage chamber 3 to flow into the constant volume chamber 4, and add 2% oxalic acid solution to the constant volume chamber 4 to make the volume reach 10 ml; open the switch valves at both ends of the third connecting channel 73, and close the switch valves at both ends of the fourth connecting channel 74. The switch valve of the third connecting channel 74 is opened, and the piston 51 is moved upward by the knob 53 to absorb 2 ml of the constant volume liquid from the constant volume chamber 4 into the second liquid storage chamber 5; the switch valves at both ends of the third connecting channel 73 are closed, and the switch valve of the fourth connecting channel 74 is opened to transfer 2 ml of the constant volume liquid into the detection test tube 6; the consumption of the 2,6-dichloroindophenol solution is measured by a glass dropper, and the consumption of the 2,6-dichloroindophenol solution divided by 2 is the volume (y) of the 2,6-dichloroindophenol solution consumed per milliliter of the test liquid, and the result is finally entered into the formula for calculation.

[0113] This specific embodiment is merely an explanation of the present invention and is not a limitation of the present invention. After reading this specification, those skilled in the art may make non-creative modifications to the present embodiment as needed. However, as long as they are within the scope of the claims of the present invention, they are protected by the patent law.

Claims

1. A device for rapid on-site detection of VC content in non-red vegetables, comprising a rectangular detection block (1), characterized in that: The rectangular detection block (1) is made of a transparent material. A residual material chamber (2), a first liquid storage chamber (3), a constant volume chamber (4) and a second liquid storage chamber (5) are arranged in sequence from left to right in the rectangular detection block (1). A detection test tube (6) with an upper end opening is arranged on the right side of the rectangular detection block (1). The bottoms of the first liquid storage chamber (3) and the second liquid storage chamber (5) are both higher than the bottoms of the residual material chamber (2), the constant volume chamber (4) and the detection test tube (6). The upper end of the first liquid storage chamber (3) is connected to the residual material chamber (2) through a first connecting channel (71); the bottom of the first liquid storage chamber (3) is connected to the constant volume chamber (4) through a second connecting channel (72); the bottom of the constant volume chamber (4) is connected to the bottom of the second liquid storage chamber (5) through a third connecting channel (73); the bottom of the second liquid storage chamber (5) is connected to the detection test tube (6) through a fourth connecting channel (74); and switch valves are provided between the bottom of the first liquid storage chamber (3) and the second connecting channel (72), between the bottom of the constant volume chamber (4) and the third connecting channel (73), between the third connecting channel (73) and the bottom of the second liquid storage chamber (5), and between the bottom of the second liquid storage chamber (5) and the fourth connecting channel (74); The residual material chamber (2) and the constant volume chamber (4) are both open at the upper ends; a plug hole (11) communicating with the first liquid storage chamber (3) is provided downwardly at the upper end of the rectangular detection block (1); a liquid inlet funnel (9) is detachably connected to the plug hole (11); a filter residue net (91) is provided in the liquid inlet funnel (9); an adjustment hole communicating with the second liquid storage chamber (5) is provided downwardly at the upper end of the rectangular detection block (1); a piston (51) is slidably connected in the second liquid storage chamber (5); a piston rod (52) is provided upwardly on the piston (51) which passes through the adjustment hole and can move up and down relative to the piston rod; a knob (53) is connected to the upper end of the piston rod (52); The method of use is as follows: when the VC content of vegetables is rapidly tested on site, the vegetables are first chopped and juiced, and the juice is added into the first liquid storage chamber (3) through the liquid inlet funnel (9), and the juice flows into the residual material chamber (2) through the first connecting channel (71); the switch valve of the second connecting channel (72) is opened to allow the juice in the first liquid storage chamber (3) to flow into the constant volume chamber (4), and oxalic acid solution is added to the constant volume chamber (4) to adjust the volume; the switch valves at both ends of the third connecting channel (73) are opened, the switch valve of the fourth connecting channel (74) is closed, and the piston (51) is moved upward by the knob (53) to absorb the constant volume liquid from the constant volume chamber (4) into the second liquid storage chamber (5); the switch valves at both ends of the third connecting channel (73) are closed, and the switch valve of the fourth connecting channel (74) is opened to allow the constant volume liquid to move into the detection test tube (6); a test tube containing 2, Determine 6-dichloroindophenol solution with a glass dropper and calculate the results.

2. The device for rapid on-site detection of VC content in non-red vegetables according to claim 1, characterized in that: Each switch valve is a sliding baffle (8), each sliding baffle (8) is penetrated by a through hole (81), each sliding baffle (8) is provided with an end block (82) at both ends, and a plurality of sliding holes for corresponding sliding baffles (8) to slide are penetrated through the rectangular detection block (1).

3. The device for rapid on-site detection of VC content in non-red vegetables according to claim 1, characterized in that: The adjustment hole is a threaded hole, and the piston rod (52) is a threaded rod.

4. The device for rapid on-site detection of VC content in non-red vegetables according to claim 1, characterized in that: The volume from the first liquid storage chamber (3) to the first connecting channel (71) is 1 ml.

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