CN116203012A - Kit for rapidly detecting protein content of milk powder - Google Patents

Abstract

A kit for rapid detection of protein content in milk powder, relating to the field of rapid detection technology, comprising a standard colorimetric card for protein content in milk powder, a rapid test card, a 4mL scale-line sample tube, a dropper and a sampling spoon, and a test paper sheet in the rapid test card The preparation method is as follows: dissolve tetrabromophenol blue in ethanol to obtain solution A; dissolve citric acid reagent and surfactant polyethylene glycol in pure water to obtain solution B, soak the test paper in solution A and dry, Then put it into the solution B for 10 seconds, take it out, and dry it; cut the dried test paper to get the test paper sheet, the invention has simple operation, high sensitivity, applicable technology, environmental protection and safety, and can carry out on-site detection of milk powder on the market without the need for instruments Auxiliary, in line with the relevant principles and requirements of promotion and application, simple training or direct operation according to the instructions, no need for professional and technical personnel, short detection time, high efficiency, low cost, safe operation, no flammable and explosive solutions, non-toxic and non-toxic Harmful, no organic reagents.

Description

A rapid detection kit for protein content in milk powder

technical field

The invention relates to the technical field of rapid detection, in particular to a rapid detection kit for protein content of milk powder.

Background technique

Milk powder is a popular nutritious food and an important food source for consumers, especially infants and young children. The quality of milk powder directly affects the life and health of consumers. At the same time, with the increase in milk powder consumption in recent years, the nutritional content of milk powder has been directly linked to the price of milk powder. The content of ingredients is seriously insufficient, long-term consumption is not good for the body, and even life-threatening in severe cases. Protein is very important to living matter and plays an important role in metabolism, immunity and life evolution. At the same time, protein is also a measure of the quality of milk powder Important indicators.

The current determination method of protein content in milk powder adopts the Kjeldahl method specified in GB/T5413.1-1997 "Determination of protein in infant formula food and milk powder". The method is to heat and digest the milk powder sample with sulfuric acid and a catalyst to decompose the protein, and the organic nitrogen in the sample is converted into ammonia, which is combined with sulfuric acid to form ammonium sulfate, followed by alkali distillation to escape ammonia and absorbed by boric acid solution Finally, titrate the boric acid solution with a standard hydrochloric acid solution, and calculate the protein content in the milk powder sample according to the amount of hydrochloric acid consumed. This method has high precision, but the test steps are cumbersome and the measurement time is long. In addition, toxic or harmful gases will be generated during the sample digestion process, which requires high experimental conditions and experimental skills of operators, and the experimental cost is also high. It can be seen that this method can only be carried out in the laboratory, and it is difficult to quickly measure the protein content of milk powder on site during circulation or sales. This has caused great restrictions and inconvenience to the quality monitoring of milk powder products, and is not conducive to the investigation and punishment of inferior milk powder.

Another commonly used method for determining protein content is the biuret method, but the conventional biuret method requires the preparation of a standard protein content colorimetric tube series each time, or the use of a spectrophotometer to measure the absorbance of a series of standard protein solutions Draw a "protein concentration-absorbance" standard curve. It can be seen that the conventional biuret method also has the disadvantages of cumbersome operation, many required instruments and equipment, and long time consumption. Therefore, this method is not suitable for on-site rapid detection of protein content in milk powder.

At present, there are many varieties of milk powder products, and the quality of the products varies. Especially in small towns and rural areas, due to the lack of simple and effective detection methods, some low-quality milk powder is harmful to the health of people, especially infants, and some have caused serious consequences. Therefore, it is necessary to develop a kit suitable for on-site rapid detection of milk protein content.

Contents of the invention

Based on the above deficiencies, the present invention proposes a rapid detection kit for milk powder protein content.

The present invention provides the following technical scheme: comprising a milk powder protein content standard color card, a quick test card, a 4mL scale line sample tube, a dropper and a sampling spoon, the preparation method of the test paper in the quick test card is as follows: tetrabromophenol Dissolve blue in ethanol to obtain solution A; dissolve citric acid reagent and surfactant polyethylene glycol in pure water to obtain solution B, soak the test paper in solution A and dry it, then put it into solution B for 10 seconds Take it out and dry it; cut the dried test paper to get a test paper piece.

Preferably, the concentration of tetrabromophenol blue is 0.4-0.6 g/L.

Preferably, the concentration of the citric acid reagent is 300-500 g/L.

Preferably, the polyethylene glycol has a concentration of 1-3 g/L.

Preferably, the volume fraction of ethanol is 5%.

Preferably, the test paper is qualitative filter paper or chromatography paper.

Preferably, the soaking time of the test paper in solution A is 2 minutes.

Preferably, the temperature required for the drying step involved in the preparation method of the test paper sheet in the quick test card is 50-60°C.

Preferably, the quick test card includes a clamping case, and the clamping case is formed by snapping the upper cover and the lower cover together, and the top surface of the lower cover is sequentially fixed with a white sponge, a white PVC board and a test paper sheet from bottom to top. The test paper sheet is aligned with the sample hole on the upper cover.

The detection method of the milk powder protein content rapid detection kit: use a sampling spoon to take 1 flat scoop of milk powder and put it into a 4mL scale line sample tube, add warm water to the scale line, mix and shake until completely dissolved, take a dropper and drop 1 drop of sample solution Put it in the sample hole of the quick test card, let it stand for 2 minutes, observe the color of the test paper in the sample hole, compare it with the color card, and judge the result

Compared with the prior art, the present invention has the beneficial effects: the present invention is simple in operation, high in sensitivity, applicable in technology, environment-friendly and safe, can carry out on-site detection of milk powder on the market without instrument assistance, and meets relevant principles and requirements for popularization and application. Simple training or direct operation according to the instructions, no need for professional and technical personnel, short detection time, high efficiency, low cost, safe operation, no flammable and explosive solutions, non-toxic and harmless, and no organic reagents.

Description of drawings

Fig. 1: is the front view of the medium-speed measuring card of the present invention.

Fig. 2: is the structural diagram of the medium-speed measuring card of the present invention.

In the figure: 1-upper cover, 2-lower cover, 3-white sponge, 4-white PVC board, 5-test paper sheet, 6-sample injection hole.

Detailed ways

The following clearly and completely describes the technical solutions in the embodiments of the invention. Obviously, the described embodiments are only some of the embodiments of the present invention, but not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the protection scope of the present invention.

Embodiment: A kit for rapid detection of protein content in milk powder, comprising a standard color card for protein content in milk powder, a rapid test card, a 4mL scale-line sample tube, a dropper and a sampling spoon.

The preparation method of the test paper sheet in the quick test card is as follows: tetrabromophenol blue is dissolved in 5% ethanol by volume fraction to obtain solution A; citric acid reagent and surfactant polyethylene glycol are dissolved in pure water to obtain For solution B, soak the test paper (qualitative filter paper or chromatographic paper) in solution A for 2 minutes, and dry it at 50-60°C, then put it in solution B for 10 seconds, take it out, and dry it at 50-60°C; The test paper was cut into 10*10mm squares to obtain test paper sheets.

Wherein, the concentration of tetrabromophenol blue is 0.4-0.6 g/L; the concentration of citric acid reagent is 300-500 g/L; the concentration of polyethylene glycol is 1-3 g/L.

As shown in Figures 1 and 2, the speed test card includes a clamping case, which is formed by snapping the upper cover 1 and the lower cover 2 together, and the top surface of the lower cover 2 is sequentially fixed with a white sponge 3, a white PVC board 4 and The test paper sheet 5 is aligned with the sample injection hole 6 on the upper cover 1 . Both the white sponge 3 and the white PVC board 4 are 15*15*3mm squares.

Among them, the milk powder protein content color comparison card is a series of standard protein solutions containing milk powder reacted with the quick test card, and the cards showing different colors are used as standard color blocks, and printed to make a color comparison that is basically consistent with the standard color blocks Card.

Wherein, the sampling spoon is a part that holds a fixed amount of milk powder, and the part can hold milk powder in a range of 0.1-0.5 g of milk powder.

Wherein, the dropper is a part that holds a fixed volume of sample liquid, and the range of dropping a drop of sample liquid from this part is 0.05-0.1 g of milk powder.

A detection method for a rapid detection kit of protein content in milk powder: use a sampling spoon to take 1 level spoon (scraped) of milk powder and put it into a 4mL scale line sample tube, add warm water to the scale line, mix and oscillate until completely dissolved, take the dropper Drop 1 drop of sample solution into the sample hole of the quick test card, let it stand for 2 minutes, observe the color of the test paper sheet in the sample hole, compare it with the color card, and judge the result.

Embodiment 1: the preparation method of the test paper sheet in the rapid test card is: solution A: take by weighing 0.5g tetrabromophenol blue and dissolve it in 5% ethanol with a volume fraction of 0.5%, so that the concentration of tetrabromophenol blue is 0.5g/L, and obtain Solution A;

Solution B: Take 500g of citric acid reagent and dissolve 3g of polyethylene glycol in pure water, wherein the concentration of citric acid reagent is 500g/L, and the concentration of polyethylene glycol is 3g/L to obtain solution B

Soak the chromatography paper in solution A for 2 minutes, take it out and dry it at 50°C, put it in solution B for 10 seconds, take it out and dry it at 50°C. Cut the dried test paper into 10*10mm squares. The white sponge and white PVC board are cut into 15*15*3mm squares.

Open the single-hole clamping case, put the white sponge and white PVC board into the detection field of view of the lower cover of the single-hole clamping case, then place the cut test paper on the PVC board, and clamp the upper cover of the single-hole clamping case tightly.

Detection: Take 1 level scoop (scratch) of milk powder and put it into a 4mL scale line sample tube, add warm water to the scale line, mix and oscillate until completely dissolved. Take a dropper and drop 1 drop of sample solution into the sample hole, let it stand for 2 minutes, observe the color of the test paper sheet in the sample hole, compare it with the color card, and judge the result.

Comparative Example 1: The production and detection of milk powder protein rapid test card are the same as in Example 1, but no polyethylene glycol is added to solution B.

Detection: Take 1 level scoop (scratch) of milk powder and put it into a 4mL scale line sample tube, add warm water to the scale line, mix and oscillate until completely dissolved. Take a dropper and drop 1 drop of sample solution into the sample hole, let it stand for 2 minutes, observe the color of the test paper sheet in the sample hole, compare it with the color card, and judge the result.

Comparative Example 2: The preparation and detection of milk powder protein rapid test card are the same as in Example 1, but the polyethylene glycol in solution B is replaced with Tween20 of the same concentration.

Detection: Take 1 level scoop (scratch) of milk powder and put it into a 4mL scale line sample tube, add warm water to the scale line, mix and oscillate until completely dissolved. Take a dropper and drop 1 drop of sample solution into the sample hole, let it stand for 2 minutes, observe the color of the test paper sheet in the sample hole, compare it with the color card, and judge the result.

Comparative Example 3: The production and detection of milk powder protein rapid test card are the same as in Example 1, but the polyethylene glycol in solution B is replaced with Tween40 of the same concentration.

Detection: Take 1 level scoop (scratched) of milk powder into a 4ml scale line sample tube, add warm water to the scale line, mix and shake until completely dissolved. Take a dropper and drop 1 drop of sample solution into the sample hole, let it stand for 2 minutes, observe the color of the test paper sheet in the sample hole, compare it with the color card, and judge the result.

Comparative Example 4: The preparation and detection of milk powder protein rapid test card are the same as in Example 1, but the polyethylene glycol in solution B is replaced with Tween60 of the same concentration.

Detection: Take 1 level scoop (scratched) of milk powder into a 4ml scale line sample tube, add warm water to the scale line, mix and shake until completely dissolved. Take a dropper and drop 1 drop of sample solution into the sample hole, let it stand for 2 minutes, observe the color of the test paper sheet in the sample hole, compare it with the color card, and judge the result.

Comparative Example 5: The production and detection of milk powder protein rapid test card are the same as in Example 1, but the polyethylene glycol in solution B is replaced with Tween80 of the same concentration.

Detection: Take 1 level scoop (scratched) of milk powder into a 4ml scale line sample tube, add warm water to the scale line, mix and shake until completely dissolved. Take a dropper and drop 1 drop of sample solution into the sample hole, let it stand for 2 minutes, observe the color of the test paper sheet in the sample hole, compare it with the color card, and judge the result.

Comparative Example 6: The preparation and detection of milk powder protein rapid test card are the same as in Example 1, but polyethylene glycol in solution B is replaced with sodium dodecylbenzenesulfonate (SDS) of the same concentration.

Detection: Take 1 level scoop (scratched) of milk powder into a 4ml scale line sample tube, add warm water to the scale line, mix and shake until completely dissolved. Take a dropper and drop 1 drop of sample solution into the sample hole, let it stand for 2 minutes, observe the color of the test paper sheet in the sample hole, compare it with the color card, and judge the result.

Comparative Example 7: The preparation and detection of milk powder protein rapid test card are the same as in Example 1, but the polyethylene glycol in solution B is replaced by TritonX-100 of the same concentration.

Detection: Take 1 level scoop (scratched) of milk powder into a 4ml scale line sample tube, add warm water to the scale line, mix and shake until completely dissolved. Take a dropper and drop 1 drop of sample solution into the sample hole, let it stand for 2 minutes, observe the color of the test paper sheet in the sample hole, compare it with the color card, and judge the result.

Table 1 Results of quick test card under different conditions

Table 2 Color rendering of the quick test card under different conditions

The detection results are shown in Table 1 and Table 2: the results show that the detection accuracy is high by using the kit of Example 1, and the detection accuracy will not be affected after a long time. And adopt the kit of embodiment 1 to develop uniform color, easy to read the result.

To sum up, when the milk powder protein quick test box detects the protein in milk powder, the method is simple, and the sample only needs two simple steps of sampling and dropping, and the detection time only takes two minutes. The present invention does not need to carry other complicated reagents, and is environmentally friendly Simultaneously, after the present invention adds the surfactant polyethylene glycol, it can ensure that the reagent on the detection membrane pad is stable, the color development is more consistent, and the detection result is more accurate and reliable.

The above is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto, any person familiar with the technical field within the technical scope disclosed in the present invention, according to the technical solution of the present invention Any equivalent replacement or change of the inventive concept thereof shall fall within the protection scope of the present invention.

Claims (10)

1. a milk powder protein content rapid detection kit, comprising milk powder protein content standard color card, quick test card, 4mL scale line sample tube, dropper and sampling spoon, it is characterized in that, test paper in the described quick test card The preparation method of the tablet is: dissolving tetrabromophenol blue in ethanol to obtain solution A; dissolving citric acid reagent and surfactant polyethylene glycol in pure water to obtain solution B, soaking the test paper in solution A and After drying, put it into solution B for 10 seconds, take it out, and dry it; cut the dried test paper to get a test paper piece. 2. A kit for rapid detection of protein content in milk powder according to claim 1, characterized in that the concentration of tetrabromophenol blue is 0.4-0.6 g/L. 3. A kit for rapid detection of protein content in milk powder according to claim 1, characterized in that the concentration of the citric acid reagent is 300-500 g/L. 4. A kit for rapid detection of protein content in milk powder according to claim 1, characterized in that the concentration of polyethylene glycol is 1-3 g/L. 5. a kind of milk powder protein content rapid detection kit according to claim 1, is characterized in that, the volume fraction of described ethanol is 5%. 6. a kind of milk powder protein content rapid detection kit according to claim 1, is characterized in that, described test paper is qualitative filter paper or chromatographic paper. 7. a kind of milk powder protein content rapid detection kit according to claim 1, is characterized in that, the immersion time of described test paper in solution A is 2min. 8. A kit for rapid detection of protein content in milk powder according to claim 1, characterized in that the temperature required for the drying step in the preparation method of the test paper sheet in the rapid test card is 50-60°C. 9. a kind of milk powder protein content rapid detection kit according to claim 1, is characterized in that, described rapid detection card comprises clamping shell, and described clamping shell adopts upper cover and lower cover to snap together to form, and described lower cover The top surface of the cover is sequentially fixed with a white sponge, a white PVC board and a test paper sheet from bottom to top, and the test paper sheet is aligned with the sampling hole on the upper cover. 10. the detection method of a kind of milk powder protein content rapid detection kit described in claim 1, is characterized in that, adopts sampling spoon to get 1 flat spoon milk powder and puts into 4mL scale line sample tube, adds warm water to scale line, mixes Shake until completely dissolved, take a dropper and drop 1 drop of sample solution into the sample hole of the quick test card, let it stand for 2 minutes, observe the color of the test paper in the sample hole, compare it with the color card, and judge the result.

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