CN103245660A - Edible oil peroxide value measurement combined reagent and detection method - Google Patents

Abstract

The present invention relates to the determination of the peroxide value, in particular to a combination reagent and detection method for the determination of the peroxide value of edible oils and fats, comprising: a polar organic solvent, a reducing agent, a color developing reagent, and a color developing stabilizer; the polar organic solvent Recorded by mass percentage, the mass concentration of ethanol is 237-710g/L; the reducing agent is recorded by weight percentage, and the mass concentration of ferrous sulfate is 1-20g/L; the color reagent is sulfosalicyl acid solution, the mass concentration is 300-1000g/L; the color stabilizer is pyridoxamine hydrochloride solution, the mass concentration is 20-800g/L. The invention adopts the method of colorimetric analysis, which is quick and easy to operate, and reduces the interference of heating on the detection results; the detection reagents used are less in types, which is convenient for assembly and carrying; the color development and detection of multiple oil samples can be carried out at the same time, and the color development is uniform; The detection reagents used are all low-toxic or even non-toxic, safe and environmentally friendly.

Description

A combined reagent and detection method for the determination of peroxide value of edible oils and fats

technical field

The invention relates to the measurement of peroxide value, in particular to a combination reagent and detection method for the determination of peroxide value of edible oils and fats. the

Background technique

As we all know, edible oily or oily food needs a certain period of time from production to consumption, and sometimes requires long-term storage. During storage or use, oily or oily food is easily affected by oxygen in the air, light, etc., and undergoes oxidation as the main body. The reaction will not only change the senses, such as deepening the color and producing unpleasant odors (mainly caused by the aldehydes formed by the easy partial decomposition of the generated peroxides), but also will cause nutritional deterioration, the degree of deterioration is serious or even Toxic substances will be produced, threatening the health of consumers. the

At present, the main methods for detecting oil oxidation products are as follows:

Iodometric method is a standard method for peroxide detection. Its principle is that in acidic medium, peroxide reacts with iodide ions to generate elemental iodine, and then titrates the precipitated iodine with sodium thiosulfate standard solution, and according to the consumption of thiosulfuric acid The volume of sodium standard solution was used to calculate the peroxide value of oil. This method is cumbersome to operate, has low sensitivity, large sampling volume, and high detection cost. It is only suitable for the determination of peroxides containing more than 0.2mEq/kg, and it is easy to cause pollution to the environment. the

The thiobarbituric acid method is a method commonly used in laboratories to detect oil oxidation. This method has a patent for detection test paper (Patent No. JP51151191). Malondialdehyde is one of the main products of many unsaturated aldehydes and ketones produced by oil oxidation. The red compound formed by it and thiobarbituric acid has a maximum absorption at 530nm, and the absorbance value of the colored substance is measured to determine Measures the degree of oxidation of fats and oils. The main disadvantage of this method is that the detection result has errors due to heating. the

Ferric thiocyanate method, its principle is that ferrous ions can be oxidized to ferric ions by peroxide under acidic conditions, and when thiocyanate ions are added, an orange-red complex is formed with ferric ions. There is a maximum absorption value within 480-515 nm, and the content of peroxide can be measured by colorimetry. However, in this method, the methanol mixed reagent dissolves the oil sample, which is harmful to the human body and pollutes the environment. the

A method for measuring the peroxide value of edible oil based on electrical conductivity (patent application number CN201210324117.6), the principle of which is to weigh a certain amount of edible oil sample, add a certain amount of isooctane and concentrated hydrochloric acid, mix well, add saturated potassium iodide Solution, after shaking, immediately add a certain amount of distilled water to dilute a certain ratio, let stand for a while after shaking, and measure the conductivity value of the mixed water phase with a conductivity meter. This type of method has high requirements for operators, and at the same time, the equipment is complicated and the cost is too high, which is not conducive to popularization and use. the

To sum up, there are big differences in the sensitivity, accuracy, detection simplicity and cost of various detection methods, so it is easy to establish a new detection method with high sensitivity, good accuracy, mild detection conditions and low cost. , a green detection method with less time consumption is still an urgent requirement of the society and an important research goal. the

Contents of the invention

In order to overcome the above disadvantages, the present invention aims to provide a combined reagent for measuring the peroxide value of edible oils and fats. The combined reagent is simple and easy to use, has high sensitivity, greatly reduces cost, and has no pollution to human body. the

Another object of the present invention is to provide a method for measuring the peroxide value of edible oils and fats. Based on the principle of colorimetry, the peroxide value of the sample to be tested is detected by a combination of reagents. The operation is simple and fast, the accuracy is high, and it is environmentally friendly and safe. the

The present invention achieves the above object through the following technical solutions: a combination reagent for measuring the peroxide value of edible oils and fats, comprising: a polar organic solvent, a reducing agent, a color developing reagent, and a color developing stabilizer;

The polar organic solvent is recorded by mass percentage, and the mass concentration including ethanol is 237～710g/L;

The reducing agent is recorded by weight percentage, including the mass concentration of ferrous sulfate is 1 ~ 20g/L;

The chromogenic reagent is a sulfosalicylic acid solution with a mass concentration of 300-1000 g/L;

The color stabilizer is pyridoxamine hydrochloride solution with a mass concentration of 20-800 g/L. the

A method for measuring the peroxide value of edible oils and fats, comprising the following steps:

(1) Pipette the liquid sample to be tested with a pipette gun. The sampling volume of the sample to be tested is 20-40 μL. At the same time, record the mass, add a mixture of polar organic solvent and color stabilizer, and The volume ratio of the test sample to the polar organic solvent is 1:15～1:25, the volume ratio of the polar organic solvent to the color stabilizer is 1:30～1:40, vortex oscillation;

(2) Add a reducing agent to the mixed solution in step (1), the volume of the reducing agent added dropwise per gram of the sample to be tested is 5-12mL, vortex and shake, and stand at room temperature;

(3) Add a color developer to the solution in step (2), the volume of the color developer added dropwise per gram of the sample to be tested is 0.1-2mL, and the solution is centrifuged at a speed above 10000r/min for 10 minutes;

(4) Take the supernatant part of the mixed solution obtained in step (3) and measure the absorbance value at 500-550 nm;

(5) Obtain the corresponding iron ion concentration from the iron ion standard curve according to the absorbance value, and convert it into the iron ion concentration per unit mass as the peroxide value. the

Preferably, the sample to be tested is in a liquid state. the

The making of described iron ion standard curve diagram comprises the following steps:

(a) After adding the reduced iron powder into hydrochloric acid and hydrogen peroxide to dissolve, heat to remove the hydrogen peroxide, dilute and mix with water after cooling to obtain a 10mg/mL iron standard stock solution;

(b) Dilute the solution prepared in step (a) with distilled water to obtain a series of gradient solutions with iron ion concentrations of 0, 0.2, 0.5, 1, 1.5, 2.0, 2.5, 3.0, 3.5, 4.0 mg/mL, Shake for 30 seconds after adding the polar solvent and color stabilizer respectively;

(c) Add reducing agent to each solution obtained in step (b), shake for 30 seconds and react for 3 minutes, then add color developing agent;

(d) Centrifuge each solution obtained in step (c) at a speed of 10,000 r/min or more for 10 minutes, and measure the absorbance value at 500-550 nm with reference to the reaction tube with an iron ion concentration of 0;

(e) Draw a curve with the absorbance value and iron ion concentration as the abscissa and ordinate, and use the least square method to obtain the fitted straight line equation. the

The beneficial effect of the present invention is that: the present invention adopts the method of colorimetric analysis, the oil sample and the combined reagent react and develop color at normal temperature, the operation is quick and easy, the interference of heating to the detection result is reduced, and the detection result is intuitive; There are fewer types of detection reagents, which are easy to assemble and carry; it can develop and detect multiple oil samples at the same time, with uniform color development, convenient and fast, and easy on-site detection; the detection reagents used are all low-toxic or even non-toxic, safe and environmentally friendly. the

Detailed ways

The present invention is further described below in conjunction with specific embodiment, but protection scope of the present invention is not limited thereto:

Embodiment 1: the combination reagent of this embodiment is polar organic solvent, reducing agent, color developing reagent, color developing stabilizer; Described polar organic solvent is recorded by volume percentage, comprises 70% ethanol; Described reducing agent is by volume percentage Weight percent record, the mass concentration that comprises ferrous sulfate is 3.6g/L; Described color reagent is sulfosalicylic acid solution, and mass concentration is 528 g/L; Described color stabilizer is pyridoxamine hydrochloride solution , with a mass concentration of 225 g/L. the

First, it is necessary to make a standard curve of iron ions. The making of described iron ion standard curve diagram comprises the following steps:

(a) After adding the reduced iron powder into hydrochloric acid and hydrogen peroxide to dissolve, heat to remove the hydrogen peroxide, dilute and mix with water after cooling to obtain a 10mg/mL iron standard stock solution;

(b) Dilute the solution prepared in step (a) with distilled water to obtain a series of gradient solutions with iron ion concentrations of 0, 0.2, 0.5, 1, 1.5, 2.0, 2.5, 3.0, 3.5, 4.0 mg/mL, Add 350 μL of polar solvent and 10 μL of color stabilizer, shake for 30 seconds;

(c) Add 150 μL of reducing agent to each solution obtained in step (b), shake for 30 seconds and react for 3 minutes, then add 10 μL of color reagent;

(d) Centrifuge each solution obtained in step (c) at a speed of 10,000 r/min or more for 10 minutes, and measure the absorbance value at 510 nm with reference to a reaction tube with an iron ion concentration of 0;

(e) Draw a curve with the absorbance value and iron ion concentration as the abscissa and ordinate, and use the least square method to obtain the fitted straight line equation. the

The sampling oil of the present embodiment is small ground sesame oil, a method for measuring the peroxide value of edible oils and fats, specifically comprising the following steps:

(1) Use a pipette gun to pipette 20 μL of small ground sesame oil, record the mass, add a mixture of 350 μL of polar organic solvent and 10 μL of color stabilizer, and vortex for 30 seconds;

(2) Add 150 μL of reducing agent to the mixture in step (1), vortex for 30 seconds, and let stand at room temperature for 3 minutes;

(3) After adding 10 μL of chromogenic reagent to the solution in step (2), centrifuge at a speed of 10,000 r/min or more for 10 minutes;

(4) Take the supernatant part of the mixed solution obtained in step (3) and measure the absorbance value at 510nm;

(5) Obtain the corresponding iron ion concentration from the iron ion standard curve according to the absorbance value, and convert it into the iron ion concentration per unit mass as the peroxide value. the

Finally, the POV value of the small milled sesame oil was determined to be 4.820mmol/Kg. the

The oil sample was serially diluted with ethanol to obtain a sensitivity of 0.087 mmol/L for the method. the

Embodiment 2: In the present embodiment, the polar organic solvent is recorded by volume percentage, including 30% ethanol; the reducing agent is recorded by weight percentage, and the mass concentration comprising ferrous sulfate is 20g/L; The color reagent is a sulfosalicylic acid solution with a mass concentration of 528 g/L; the color stabilizer is a pyridoxamine hydrochloride solution with a mass concentration of 225 g/L. the

The sampling oil in this embodiment is corn oil, and 20 μL of corn oil is pipetted with a pipette gun, and other implementation methods are the same as in Example 1. the

Finally, the POV value of the corn oil measured was 1.051mmol/Kg. the

The oil sample was serially diluted with ethanol to obtain a sensitivity of 0.094 mmol/L for the method. the

Embodiment 3: In the present embodiment, the polar organic solvent is recorded by volume percentage, including 90% ethanol; the reducing agent is recorded by weight percentage, and the mass concentration including ferrous sulfate is 1g/L; The color reagent is a sulfosalicylic acid solution with a mass concentration of 528g/L; the color stabilizer is a pyridoxamine hydrochloride solution with a mass concentration of 225g/L. the

The sampling oil in this embodiment is rapeseed oil, and 20 μL of rapeseed oil is pipetted with a pipette gun, and other implementation methods are the same as in Example 1. the

Finally, the POV value of rapeseed oil measured was 1.119mmol/Kg. the

The oil sample was serially diluted with ethanol to obtain a sensitivity of 0.121 mmol/L for the method. the

Embodiment 4: In the present embodiment, the polar organic solvent is recorded by volume percentage, including 70% ethanol; the reducing agent is recorded by weight percentage, and the mass concentration comprising ferrous sulfate is 1g/L; The color reagent is a sulfosalicylic acid solution with a mass concentration of 1000g/L; the color stabilizer is a pyridoxamine hydrochloride solution with a mass concentration of 225g/L. the

The sampling oil in this embodiment is soybean oil, and 20 μL of soybean oil is pipetted with a pipette gun, and other implementation methods are the same as in Example 1. the

Finally, the POV value of the soybean oil measured was 0.960mmol/Kg. the

The oil sample was serially diluted with ethanol to obtain a sensitivity of the method of 0.134 mmol/L. the

Embodiment 5: In the present embodiment, the polar organic solvent is recorded by volume percentage, including 70% ethanol; the reducing agent is recorded by weight percentage, and the mass concentration comprising ferrous sulfate is 20g/L; The color reagent is a sulfosalicylic acid solution with a mass concentration of 300g/L; the color stabilizer is a pyridoxamine hydrochloride solution with a mass concentration of 225g/L. the

The sampling oil in this embodiment is peanut oil, and 20 μL of peanut oil is pipetted with a pipette gun, and other implementation methods are the same as in Example 1. the

Finally, the POV value obtained by measuring peanut oil was 1.910mmol/Kg. the

The oil samples were serially diluted with ethanol to obtain a sensitivity of 0.100 mmol/L for the method. the

Embodiment 6: In the present embodiment, the polar organic solvent is recorded by volume percentage, including 70% ethanol; the reducing agent is recorded by weight percentage, and the mass concentration including ferrous sulfate is 3.6g/L; The color developing reagent is a sulfosalicylic acid solution with a mass concentration of 1000g/L; the color developing stabilizer is a pyridoxamine hydrochloride solution with a mass concentration of 200g/L. the

The sampled oil in this embodiment is grain blended oil, and 20 μL of the grain blended oil is pipetted with a pipette gun, and other implementation methods are the same as in Example 1. the

Finally, the POV value of the corn blended oil was determined to be 0.920mmol/Kg. the

The oil sample was serially diluted with ethanol to obtain a sensitivity of the method of 0.115 mmol/L. the

Embodiment 7: In the present embodiment, the polar organic solvent is recorded by volume percentage, including 70% ethanol; the reducing agent is recorded by weight percentage, and the mass concentration including ferrous sulfate is 3.6g/L; The color developing reagent is a sulfosalicylic acid solution with a mass concentration of 300g/L; the color developing stabilizer is a pyridoxamine hydrochloride solution with a mass concentration of 800g/L. the

The sampling oil in this embodiment is olive oil, and 20 μL of olive oil is pipetted with a pipette gun, and other implementation methods are the same as in Example 1. the

Finally, the POV value of the olive oil measured was 5.47mmol/Kg. the

The oil sample was serially diluted with ethanol to obtain a sensitivity of 0.114 mmol/L for the method. the

Embodiment 8: In the present embodiment, the polar organic solvent is recorded by volume percentage, including 70% ethanol; the reducing agent is recorded by weight percentage, and the mass concentration including ferrous sulfate is 1g/L; The color reagent is a sulfosalicylic acid solution with a mass concentration of 528g/L; the color stabilizer is a pyridoxamine hydrochloride solution with a mass concentration of 800g/L. the

The sampled oil in this example is the residual oil in canned dace with tempeh. Use a pipette gun to pipette 20 μL of the residual oil in canned dace with tempeh. Other implementation methods are the same as in Example 1. the

Finally, the POV value of the residual oil in the canned dace with tempeh was determined to be 2.960mmol/Kg. the

The oil sample was serially diluted with ethanol to obtain a sensitivity of the method of 0.099 mmol/L. the

Embodiment 9: In the present embodiment, the polar organic solvent is recorded by volume percentage, including 70% ethanol; the reducing agent is recorded by weight percentage, and the mass concentration including ferrous sulfate is 3.6g/L; The color developing reagent is a sulfosalicylic acid solution with a mass concentration of 528g/L; the color developing stabilizer is a pyridoxamine hydrochloride solution with a mass concentration of 225g/L. the

The sampled oil in this example is peanut oil, rapeseed oil, olive oil, small ground sesame oil, grain blended oil, soybean oil, and corn oil mixed in equal proportions. Use a pipette to pipette 20 μL of the mixed oil. Other embodiments Same as Example 1. the

Finally, the measured POV value of the mixed oil was 7.730mmol/Kg. the

The oil sample was serially diluted with ethanol to obtain a sensitivity of 0.087 mmol/L for the method. the

Embodiment 10: In the present embodiment, the polar organic solvent is recorded by volume percentage, including 70% ethanol; the reducing agent is recorded by weight percentage, and the mass concentration including ferrous sulfate is 3.6g/L; The color developing reagent is a sulfosalicylic acid solution with a mass concentration of 528g/L; the color developing stabilizer is a pyridoxamine hydrochloride solution with a mass concentration of 225g/L. the

The sampled oil in this embodiment is fish oil, and 20 μL of fish oil is pipetted with a pipette gun, and other implementation methods are the same as in Example 1. the

Finally, the POV value of the fish oil measured was 8.920mmol/Kg. the

The oil sample was serially diluted with ethanol to obtain a sensitivity of 0.087 mmol/L for the method. the

Embodiment 11: In the present embodiment, the polar organic solvent is recorded by volume percentage, including 70% ethanol; the reducing agent is recorded by weight percentage, and the mass concentration including ferrous sulfate is 3.6g/L; The color developing reagent is a sulfosalicylic acid solution with a mass concentration of 528g/L; the color developing stabilizer is a pyridoxamine hydrochloride solution with a mass concentration of 225g/L. the

The sampling fat in this embodiment is lard, and 20 μL of lard is pipetted with a pipette gun, and other implementation methods are the same as in Example 1. the

Finally, the POV value obtained by measuring lard is 3.810mmol/Kg. the

The oil sample was serially diluted with ethanol to obtain a sensitivity of 0.087 mmol/L for the method. the

The above descriptions are specific embodiments of the present invention and the technical principles used. If changes are made according to the conception of the present invention, and the functions produced by it still do not exceed the spirit covered by the description, it should still belong to the present invention. scope of protection. the

Claims (4)

1. A combination reagent for measuring the peroxide value of edible oils and fats is characterized in that it comprises: a polar organic solvent, a reducing agent, a chromogenic reagent, and a chromogenic stabilizer; The polar organic solvent is recorded by mass percentage, and the mass concentration including ethanol is 237～710g/L; The reducing agent is recorded by weight percentage, including a mass concentration of ferrous sulfate of 1 to 20 g/L; The chromogenic reagent is a sulfosalicylic acid solution with a mass concentration of 300-1000 g/L; The color stabilizer is pyridoxamine hydrochloride solution with a mass concentration of 20-800 g/L. 2. A method for measuring the peroxide value of edible oils and fats is characterized in that it may further comprise the steps: (1) Pipette the liquid sample to be tested with a pipette gun. The sampling volume of the sample to be tested is 20-40 μL. At the same time, record the mass, add a mixture of polar organic solvent and color stabilizer, and The volume ratio of the test sample to the polar organic solvent is 1:15 to 1:25, the volume ratio of the polar organic solvent to the color stabilizer is 1:30 to 1:40, and vortexed; (2) Add a reducing agent to the mixed solution in step (1), the volume of the reducing agent added dropwise per gram of the sample to be tested is 5-12mL, Vortex, stand at room temperature; (3) Add a color developer to the solution in step (2), the volume of the color developer added dropwise per gram of the sample to be tested is 0.1-2mL, and the solution is centrifuged at a speed above 10000r/min for 10 minutes; (4) Take the supernatant part of the mixed solution obtained in step (3) and measure the absorbance value at 500-550 nm; (5) Obtain the corresponding iron ion concentration from the iron ion standard curve according to the absorbance value, and convert it into the iron ion concentration per unit mass as the peroxide value. 3. a kind of edible oil peroxide value measuring method according to claim 2 is characterized in that, described sample to be tested is liquid state. 4. a kind of edible oil peroxide value determination method according to claim 2, is characterized in that, the making of described iron ion standard graph comprises the following steps: (a) Add the reduced iron powder to hydrochloric acid and hydrogen peroxide to dissolve, heat to remove the hydrogen peroxide, dilute and mix with water after cooling, and prepare a 10 mg/mL iron standard stock solution; (b) Dilute the solution prepared in step (a) with distilled water to obtain a series of gradient solutions with iron ion concentrations of 0, 0.2, 0.5, 1, 1.5, 2.0, 2.5, 3.0, 3.5, 4.0 mg/mL, Shake for 30 seconds after adding the polar solvent and color stabilizer respectively; (c) Add reducing agent to each solution obtained in step (b), shake for 30 seconds and react for 3 minutes, then add color developing agent; (d) Centrifuge each solution obtained in step (c) at a speed of 10,000 r/min or more for 10 minutes, and measure the absorbance value at 500-550 nm with reference to the reaction tube with an iron ion concentration of 0; (e) Draw a curve with the absorbance value and iron ion concentration as the abscissa and ordinate, and use the least square method to obtain the fitted straight line equation.