CN1036615C - Test paper and solvent for detecting peroxide content in edible oil and fat-containing food - Google Patents

Abstract

The invention discloses a quantitative detection test paper for quickly measuring the peroxide content in edible oil and fat-containing solid food and a matching solvent required when using the test paper to detect the peroxide content in the fat-containing solid food. The detection of the peroxide content is fast and simple, and the stability is good and the storage period is long, so it can be widely used in the production, storage, transportation, sales and consumption of grain, oil and food. The test paper is made by soaking filter paper in a soaking solution for a certain period of time and then dehydrating and drying. The soaking solution includes starch, potassium iodide, titanium dioxide, alcohol ether stabilizers, sensitizers and water.

Wherein said alcohol ether stabilizer is a compound represented by the following formula:

[RX-(CH ₂ ) _m -Y-R']

R,R'＝-H,-CH _{3 ,} -CH＝CH _2, -CH ₂ OH,

-CH ₂ SH, -C ₂ H ₄ OH,

-C ₂ H ₄ SH, -C ₃ H ₆ SH, -C ₃ H ₆ OH

X,Y=O,S.Se

m=1-7

The sensitizer is a citric acid compound

The measuring range of the test paper reaches 0-200 meq/kg, the sensitivity is better than 5 meq/kg, and the accuracy is high.

Description

Test paper and solvent for detecting peroxide content in edible oil and fat-containing food

The invention relates to a test paper for quickly detecting the peroxide content in edible oil and fat-containing food and a matching solvent required when using the test paper to detect the peroxide content in fat-containing solid food.

Edible oil and fat-containing solid food will undergo oxidative deterioration after a certain period of storage to produce toxic peroxides and deep oxidation products, which will greatly damage the health of eaters. It is of practical significance to measure its content in time to understand the quality of oil-containing food in grain and oil, food production, storage, transportation, sales, and consumption.

At present, there are HPLC method, ESR method, titration method, etc. for the determination of peroxide generated by oil oxidation. However, these methods all use instruments and equipment, require the measurement personnel to have a high level of analysis skills, and cannot perform rapid measurement on site. In recent years, China and Japan have published the patent literature on the detection of peroxide with test paper, such as Chinese patent (CN87106131.7) "peracetic acid test paper and its preparation method" refers to the determination of peracetic acid content in water-soluble disinfectant. However, the peroxides in edible oil and fat-containing solid foods are more complicated, and their total content really reflects the degree of food deterioration, and there is no research result in this regard Japanese patent (Shao 53-30383) discloses "grease "Preparation method of test paper for the determination of peroxides", which uses starch, potassium iodide and sodium thiosulfate as the main components, but because sodium thiosulfate has a strong reducing property, it will react with the peroxide in the test object No chromogenic substances are generated, thus reducing the detection sensitivity. At the same time, because sodium thiosulfate is easy to react with O3, the test paper has poor stability in the air and is easy to change color.

The purpose of the present invention is to develop a kind of test paper for detection, which is applicable to the rapid determination of the peroxide content in non-decolorized edible oil, decolorized edible oil and fat-containing solid food. The invention can increase the stability of the test paper, make the color scale obvious, thereby improving the sensitivity of the test.

Contents of the present invention:

1. A test for determining the content of peroxide in edible oil or fat-containing food

Paper, made by soaking filter paper in a soaking solution for a certain period of time and then dehydrating and drying

Formed, the soaking solution includes starch, potassium iodide, titanium dioxide, alcohol ether stable

Stabilizer, sensitizer and water,

Among them, the alcohol ether stabilizer is a compound represented by the following formula:

[RX-(CH ₂ ) _m -Y-R']

R, R'=-H, _-CH3 ,-CH= _CH2 , _-CH2OH , _-CH2SH ,

_{-C2H4OH , -C2H4SH , -C3H6SH , -C3H6OH _}

X, Y=O, S, Se

m=1-7

  The sensitizer is a citric acid compound

The proportions of various components in the soaking solution are as follows (parts by weight):

Starch: 1

Potassium iodide: 0.15

Titanium dioxide: 0.005-0.5

       Alcohol ether stabilizers: 0.01-2

Sensitizer: 0.005-0.5

Water: 30-100

2. Special solvent: It is a kind of solvent that is prepared for the determination of peroxide in fat-containing solid food with test paper. It is a solvent composed of glacial acetic acid, chloroform, ether, and petroleum ether. The composition ratio (by weight parts )for:

Glacial acetic acid: 1

Chloroform: 0.2-5

Ether: 0-11.0

Petroleum ether: 0-5.5

3. The preparation method of the test paper is prepared according to the following steps:

1) Dissolve starch in hot distilled water (60-100°C), cool to room temperature, the ratio of starch to water is 1:30-100

2) Dissolve reagents such as KI, TiO ₂ , stabilizer [RX-(CH ₂ ) _m -Y-R'] and sensitizer in the starch solution according to the composition ratio.

3) Soak the qualitative filter paper in the solution for 0.5-15 minutes, and filter the excess solution.

4) The filter paper is dried at a drying temperature of 60-200°C.

5) Cut the dried test paper into strips, and pack it in a vacuum aluminum foil bag with O _removal agent for later use.

4. The making method of color plate: the peroxide standard solution of preparation various content makes it and measuring test paper effect, uses the existing test paper of various colors as the standard color plate of preparation same color. Use several different inks to print in different dot percentage ratios to form a permanent standard color plate that is basically consistent with the color development of the test paper. (see Attachment)

5. How to use:

①Liquid oily food: Use a dropper to take liquid edible oil or oily food and drop it on the test paper. After five minutes, compare the color displayed on the test paper with the standard color plate. Oxide content, retest five times, take the average value

② Solid fat-containing food: Weigh 25 grams of crushed and mixed solid fat-containing food into an iodine measuring bottle, add 50 ml of the above-mentioned special solvent, immerse for a period of time, shake well, clarify, take the supernatant liquid and drop it on the test paper, put the test paper Displayed colors and labels

  Compare with the standard color board, the number marked directly below the corresponding color is the color of the object under test.

The peroxide content was measured five times and the average value was taken. (unit: milligram equivalent/thousand

gram)

The outstanding features of the present invention compared with prior art:

1) The peroxide content can be quickly and quantitatively given, easy to carry and on-site test, with high accuracy, and the measurement range reaches 0-200 mg equivalent/kg.

2) RX-(CH ₂ ) _M -Y-R' itself has good stability and improves the stability of the test paper.

3) The whitening agent _TiO2 increases the color contrast of the test paper, the color gradation is obvious, and it is easy to observe, so that the sensitivity can reach 5 mg/kg.

4) Deoxidizer and vacuum aluminum foil bag extend the storage period of test paper.

5) The color gradation of the standard color board is obvious. When the peroxide content is 0-100 meq/kg, the color gradation difference is 5 meq/kg. When the peroxide content is 100-200 meq/kg, the color The step difference is 10 meq/kg.

6) The special mixed solvent used when measuring solid is better than the single solvent usually used in the past.

Best practice:

1. Dissolve 30 grams of starch in 3000 ml of 60-100°C distilled water, cool to room temperature, then dissolve 25 grams of potassium iodide, 0.05 grams of titanium dioxide, 2.5 grams of propylene glycol, and 10 grams of citric acid compound sensitizers in the starch solution. After immersing the qualitative filter paper for 5 minutes, take out the filtered test solution and place it in a desiccator to dry. Cut the dried test paper into 6×1cm paper strips, and pack the paper strips together with the deoxidizer and standard color plates packaged into small packages in a vacuum aluminum foil bag for later use. The test paper can be used for the detection of peroxides in oily foods. Drop the edible oil to be tested on the test paper, and after 5 minutes, compare the color displayed on the test paper with the standard color plate to determine the content of peroxides in the food. .

2. Divide and seal the special solvent by 50ml, and use this solvent to detect the content of peroxide in solid food containing fat. The specific steps are: weigh 25 grams of ground fat-containing solid food, dissolve it in 50 ml of solvent, shake it up for 30 minutes, clarify it, take the upper solution and drop it on the test paper, and compare the color displayed on the test paper with the standard color plate in 1 minute. Know the peroxide content.

3. Dissolve 60 grams of starch in 3000ml of water (60-100°C), cool to room temperature, then add 13 grams of potassium iodide, 20 grams of thiobis-hexyl alcohol, 3 grams of titanium dioxide, 7.5 grams of citric acid compound sensitizer and other reagents Dissolve in starch solution, immerse qualitative filter paper for 10 minutes, take out and filter dry, dry in desiccator, cut and package for later use.

Standard color plate of test paper for rapid detection of peroxide content in edible oil and grease food

Figure A Liquid oily food (soybean oil) standard

Figure B Liquid oily food (vegetable oil) standard

            Figure C Food Standards for Solid Oils and Fats

Claims (2)

1. A test paper for measuring the peroxide content in edible oil or fat-containing food, which is formed by soaking filter paper in a soaking solution for a certain period of time and then dehydrating and drying. The soaking solution includes starch, potassium iodide, titanium dioxide, alcohol ether stabilizers, sensitizers and water, Wherein said alcohol ether stabilizer is a compound represented by the following formula: [RX-(CH ₂ ) _m -Y-R'] R, R'=-H, -CH ₃ , -CH=CH ₂ , -CH ₂ OH, -CH ₂ SH, -C ₂ H ₄ OH, -C ₂ H ₄ SH, -C ₃ H ₆ SH, -C ₃ H ₆ OH X, Y=O, S, Se m=1-7 The sensitizer is a citric acid compound The proportions of various ingredients in the soaking liquid are as follows (parts by weight): Starch: 1 Potassium iodide: 0.1-5 Titanium dioxide: 0.005-0.5   Alcohol ether stabilizer: 0.01-2 Sensitizer: 0.005-0.5 Water: 30-100 2, a kind of solvent used when utilizing the test paper described in claim 1 to measure the peroxide content in the fat-containing solid food, is made of glacial acetic acid, chloroform, ether, sherwood oil, and its composition ratio (by weight parts) )for: Glacial acetic acid: 1 Chloroform: 0.2-5 Ether: 0-11.0 Petroleum ether: 0-5.5