GB/T 5539-1985 Inspection of vegetable oils and fats Qualitative tests for oils and fats
Some standard content:
National Standard of the People's Republic of China
Inspection of vegetable oilsQualitative test of oils
This standard applies to the test for judging the quality and purity of commercial vegetable oils. Tung oil thermal polymerization test
1.1 Apparatus and utensils
1.1.1 Blowtorch;
1.1.2 Metal pot: round bottom, about 5cm high, about 15cm in diameter; 1.1.3 Balance: sensitivity 0.01g:
1.1.4 Thermometer: 350℃;
1.1.5 Stopwatch;
1.1.6 Glass rod, etc.
1.2 Operation method
GB/T5539—85
Weigh 100g of the mixed sample and inject it into a metal pot. Hang a thermometer (mercury ball immersed in oil) and place it on a blowtorch to heat it. It will reach 282℃ within 4 minutes, that is, 105℃ in the first minute; 180℃ in the second minute; 240℃ in the third minute; 265℃ in three and a half minutes;
282℃ in the fourth minute. Adjust the flame of the lamp and fix it at 282℃. Start timing at the same time and stir it with a glass rod until it is completely gelled. The total time for pure tung oil to gel from 282℃ to complete gelling is no more than 71/2min. The time from initial coagulation into a linear shape to complete gelling is about 40s. The gelled product is light yellow and translucent. Take out a piece 1min after gelling and cool it for 2min. It will not stick to the knife when cut with a knife
, and it will be pressed into powder with a knife. The difference between the two test results is allowed to be no more than 10 seconds, and the average is taken as the test result. 2
β-tung oil test
The presence of β-tung oil indicates that tung oil is unstable. 2.1
Instruments and utensils
Test tubes, refrigerators, etc.
2.2 Operation method
Inject the mixed and filtered sample into a dry test tube (about one-third of the test tube capacity), plug it with a cork, place it in a refrigerator, and cool it at a temperature of 3.3-4.5℃ for 24 hours. If crystals are precipitated, β-tung oil exists. Note: The crystals of β-tung oil are needle-shaped and have a melting point of 62℃. 3 Detection of tung oil
3.1 Antimony trichloride chloroform solution method
This method is applicable to oils and fats mixed with 0.5% tung oil in rapeseed oil, peanut oil, and tea oil. 3.1.1 Apparatus and equipment
3.1.1.1 Measuring cylinder, test tube;
3.1.1.2 Constant temperature water bath.
3.1.2 Reagents
Chloroform trichloride solution: Dissolve 10g antimony trichloride in 100ml chloroform, stir, and dissolve it with slight heat if necessary.
Filter if there is precipitation.
3.1.3 Operation method
Measure 1ml of the mixed sample and inject it into the test tube, then add 1ml of 1% chloroform trichloride solution along the inner wall of the tube mouth, so that the solution in the tube is divided into two layers, and heat it in a water bath at a temperature of 40℃ for 8 to 10 minutes. If tung oil is present, a purple-red to dark brown ring will appear on the interface between the two layers of solution.
3.2 Sodium nitrite method
This method is applicable to the detection of tung oil mixed in soybean oil, cottonseed oil and dark oil, but not applicable to sesame oil and catalpa oil. 3.2.1 Instruments and appliances
3.2.1.1 Measuring cylinder
3.2.1.2 Test tube.
3.2.2 Reagents
3.2.2.1 Sodium nitrite, petroleum ether;
3.2.2.2 10N sulfuric acid: Take 27.5ml concentrated sulfuric acid (specific gravity 1.84) and slowly pour it into 72.5ml water and stir evenly. 3.2.3 Operation method
Take 5 to 10 drops of the mixed sample into a test tube, add 2ml petroleum ether to dissolve the sample (filter if necessary). Add a small amount of sodium nitrite to the solution (or filtrate), add 1ml 10N sulfuric acid, shake well and let it stand. If tung oil is present, the solution will be turbid and flocculent masses will precipitate. It will be white at first and turn yellow after standing. 3.3 Sulfuric acid method
Add a few drops of oil sample on a white porcelain plate, and add 1 to 2 drops of concentrated sulfuric acid. If tung oil is present, a deep red color will appear and solidify. The color will gradually deepen and finally turn into carbon black. 4 Detection of sesame oil
4.1 Take a small amount of the mixed sample and inject it into nickel evaporation blood, add a small piece of potassium hydroxide, and slowly heat it to melt it. If there is an odor of octanol, it indicates the presence of sesame oil.
4.2 Or dissolve the above melt in water, then add an excess of magnesium chloride solution to precipitate fatty acids, filter, and adjust the filtrate to acidity with dilute hydrochloric acid. If crystals precipitate, it indicates the presence of sesame oil. 5 Detection of linseed oil
Take 0.5ml of the mixed and filtered sample and inject it into a 20ml colorimetric tube with a stopper, add 10ml of ether and 3ml of bromine solution, add
stopper after dissolving, reverse and mix, adjust the solution temperature to 25℃, if linseed oil exists, it will become turbid within 2min. Note: ① Bromine solution: add enough bromine to carbon tetrachloride to increase the capacity by half. ② Take another normal sample for control test.
6 Detection of mineral oil
This method can detect mineral oil with a content of more than 0.5%. Take 1ml of the mixed sample and inject it into a conical flask, add 1ml of potassium hydroxide solution (3:2) and 25ml of anhydrous ethanol, connect an air
condenser, reflux and boil for about 5min, and shake frequently until saponification is completed. Add 25ml of boiling water and shake well. If mineral
oil exists, it will appear obvious turbidity or oily matter will precipitate. Detection of soybean oil
Measure 5 ml of the mixed sample and inject it into a test tube, add 2 ml of chloroform and 3 ml of 2% potassium nitrate solution, and shake the test tube vigorously to make the solution emulsified. If the emulsion is lemon yellow, it means that soybean oil is present. If peanut oil, sesame oil and corn germ oil are present, the emulsion will be white or slightly yellow. 8 Detection of peanut oil
Peanut oil is a glyceride composed of about 5% arachidic acid. Arachidic acid is insoluble in ethanol and has a melting point of 75.3. 8.1 Instruments and appliances
Conical flask: 150 ml;
8.1.2 Constant temperature water bath;
8.1.3 Pipette;
8.1.4 Thermometer, measuring cylinder, etc.
8.2 Reagents
8.2.11.5N potassium hydroxide ethanol solution.
8.2.2, 70% ethanol: add 30 parts of water to 70 parts of anhydrous ethanol. 8.2.3 Hydrochloric acid: specific gravity 1.16, measure 83 ml of concentrated hydrochloric acid, add water to 100 ml. 8.3 Operation method
Accurately measure 1 ml of the mixed sample and inject it into a conical flask, add 5 ml of 1.5N potassium hydroxide ethanol solution, connect an air condenser
tube, heat and saponify in a water bath for 5 minutes, add 50 ml of 70% ethanol and 0.8 ml of hydrochloric acid, heat and dissolve the precipitate, and place it
in a low-temperature water bath, stir continuously with a thermometer, and make the cooling rate reach about 1°C per minute. Observe the temperature when turbidity occurs at any time: olive oil before 90°C; rapeseed oil before 22.5°C; cottonseed oil, rice bran oil and soybean oil before 13°C; sesame oil before 15°C will become turbid, indicating the presence of peanut oil. Note: ① If necessary, 90% ethanol can be used to wash the peanut acid to determine the melting point. ② The small amount of milky white that occurs after the oil becomes acid is not the turbidity point. If turbidity occurs, repeat the cooling and observation once, and the turbidity of the second time shall prevail. Detection of sesame oil
This method can detect sesame oil containing more than 0.25%. 9.1 Instruments and appliances
9.1.1 Colorimetric tube;
9.1.2 Measuring cylinder, etc.
9.2 Reagents
9.2.1 Concentrated hydrochloric acid:
9.2.22% furfural ethanol solution: Add 2ml furfural to 100ml 95% ethanol and mix well. 9.3 Operation method
Measure 5 ml of the mixed sample and concentrated hydrochloric acid and inject them into a colorimetric tube, mix well, add 0.1 ml of 2% furfural ethanol solution, mix thoroughly, shake for 30 seconds, let stand for 10 minutes, and observe the color produced. If dark red appears, add 10 ml of water and shake again. If the red disappears, it means that there is no sesame oil; if the red does not disappear, it means that there is sesame oil. Note: ① When testing dark oil samples, alkali bleaching can be used, and the alkali and water in the oil can be removed. ② If necessary, a sample containing sesame oil can be used as a control test. 10 Detection of cottonseed oilbZxz.net
This method belongs to the Halfin test and can detect cottonseed oil mixed with more than 0.2%. 10.1 Instruments and utensils
10.1.1 Test tube;
10.1.2 Constant temperature water bath;
10.1.3 Measuring cylinder.
10.2 Reagents
10.2.11% sulfur powder and carbon disulfide solution; 10.2.2 Pyridine or amyl alcohol;
10.2.3 Saturated salt water.
10.3 Operation method
Measure 5 ml of the mixed sample and 1% sulfur powder carbon disulfide solution and inject them into a test tube. Add 2 drops of pyridine (or amyl alcohol) and shake well. Place it in a saturated salt water bath and slowly heat it until the salt water begins to boil. After 40 minutes, take out the test tube for observation. If dark red or orange-red appears, it indicates the presence of cottonseed oil. The darker the color, the more cottonseed oil. 11 Detection of rapeseed oil
Both rapeseed oil and mustard oil contain unique erucic acid. Therefore, if the erucic acid content is above 4%, it means the presence of rapeseed oil or mustard oil.
11.1 Apparatus and equipment
11.1.1 Conical flask: 150ml;
11.1.2 Condenser;
Constant temperature water bath;
Electric furnace;
Glass filter crucible (No. 3);
Filtration device;
Volume flask: 1000ml;
Graduating cylinder, burette, reagent bottle, iodine value bottle, etc.; 11.1.9 Balance: sensitivity 0.001g.
11.2 Reagents
Potassium hydroxide ethanol solution: 80ml of 25% KOH (specific gravity 1.24) solution, dilute to 1000ml with 95% ethanol;11.2.2
Lead acetate solution: 50g lead acetate mixed with 5ml90% acetic acid, dilute to 1000ml with 80% ethanol;0.2N iodine ethanol solution: 5.07g sublimated iodine dissolved in 200ml95% ethanol. Prepare immediately before use;Ethanol acetic acid mixture: 1 part 95% ethanol mixed with 1 part 96% acetic acid;11.2.570% ethanol;
11.2.60.1N sodium thiosulfate solution;
11.2.7 Starch indicator.
11.3 Operation method
Weigh 0.500-0.510g of the mixed sample and inject it into a 150ml conical flask, add 50ml potassium hydroxide ethanol solution, connect
condenser, place it in a water bath and heat for 1h, add 20ml lead acetate solution and 1ml90% acetic acid to the saponified solution, and then continue to heat until the lead salt is dissolved. Remove the conical flask, wait for the solution to cool slightly, add 3ml of water, shake the spoon, place it in a 20℃ incubator and let it stand for 14h, transfer the precipitate to a glass filter crucible, and wash the conical flask and precipitate with 12ml of 70% ethanol at 20℃ several times. Move the crucible to the iodine value bottle, dissolve the precipitate into the iodine value bottle with 20ml of hot ethanol and acetic acid mixture, and then wash it with 10ml of hot ethanol and acetic acid mixture. Pipette 20ml of 0.2N iodine ethanol solution into the iodine value bottle, shake well, add 200ml of water immediately, shake well again, and let it stand in the dark for 1h. Then titrate with 0.1N sodium thiosulfate solution until the solution turns light yellow, add 1ml starch indicator, shake well, and continue titrating until the blue color disappears. At the same time, use 30ml of ethanol and acetic acid mixture for blank test. 11.4 Calculation of results
Erucic acid content is calculated according to the following formula:
(V1-V2)× N × 0.169
Erucic acid (%)
Where: V1 is the volume of sodium thiosulfate solution used for blank test, ml; V2 is the volume of sodium thiosulfate solution used for sample, ml; N is the equivalent concentration of sodium thiosulfate solution;
0.169 is the number of milligrams of erucic acid equivalent to each milligram equivalent of sodium thiosulfate: W is the weight of sample, g.
The allowable difference between the two test results shall not exceed 0.2%. The average shall be the test result. The test result shall be rounded to the first decimal place.
12 Detection of lard in vegetable oil
According to the different shapes of various oil crystals, lard is detected by microscopic examination. 12.1 Instruments and appliances
12.1.1 Test tube: 20ml;
12.1.2 Refrigerator,
12.1.3 Microscope: 400 times;
12.1.4 Glass tube: inner diameter 3mm.
12.2 Reagents
12.2.1 Ether
12.2.2 Cotton wool
12.3 Operation method
Take 3 20ml test tubes, wash and dry them, and number them 1, 2, and 3. Add 10ml of ether to each. Add 2 ml of the oil sample to be tested to tube 1; add 1 ml of melted lard to tube 2; add 2 ml of pure oil to be tested to tube 3. Plug the mouths of the three tubes with absorbent cotton and place them in a refrigerator or ice water. After the crystals precipitate (about 10 hours), observe under a microscope. No crystals should precipitate in tube 3 (raisin oil); white crystals precipitate in tube 2; if there is lard in tube 1, white crystals will also precipitate, and the amount of precipitation is proportional to the lard content. Identification of lard crystals: drop a drop of pure oil on a glass slide, use a glass tube with an inner diameter of 3 mm to absorb half a drop of crystals and add it to the oil drop, add a cover slide and observe under a microscope. The lard crystals are slender or needle-shaped. 13 Detection of tea oil
13.1 Instruments and utensils
13.1.1 Test tube: 50ml;
13.1.2 Constant temperature water bath;
13.1.3 Measuring cylinder, etc.
13.2 Reagents
13.2.1 Acetic anhydride;
13.2.2 Dichloromethane;
13.2.3 Concentrated sulfuric acid;
13.2.4 Anhydrous ether.
13.3 Operation method
Measure 0.8ml of acetic anhydride, 1.5ml of dichloromethane and 0.2ml of concentrated sulfuric acid and inject them into a test tube. After mixing, cool to room temperature. Add 7 drops of
sample (about 0.22g) to the tube, mix and cool. If the solution is turbid, add acetic anhydride dropwise, shaking while dropping until it suddenly becomes clear. After standing for 5 minutes, measure 10ml of anhydrous acetaldehyde and inject it into the color developing solution. Immediately invert it once to mix. Within about 1 minute, the tea oil will produce brown, then turn dark red, and slowly fade within a few minutes. After adding anhydrous ether, olive oil is initially green, slowly turns brown-gray, and sometimes goes through a light red process in the middle. The mixed oil of olive oil and tea oil shows the color reaction of tea oil, and the color depth is proportional to the tea oil content. If colorimetric quantification is required, after the above method is allowed to stand for 5 minutes, place the test tube in an ice-water bath for 1 minute, inject 10 ml of anhydrous ether cooled by ice water
and mix, and then place it in the ice-water bath for 1 to 5 minutes. The color depth can reach the highest peak. Use a sample with a known tea oil content and the sample to be tested, and select the deepest red for colorimetric quantification. 14 Tea Oil Purity Test
14.1 Instruments and Utensils
Test tubes, measuring cylinders, etc.
14.2 Reagents
14.2.1 Resin powder carbon disulfide saturated solution: Weigh 2 to 3 g of pure resin powder and dissolve it in 100 ml of carbon disulfide. Shake it vigorously for a few minutes to make it a saturated solution. Filter it with filter paper and set aside. 14.2.2 Concentrated nitric acid.
14.3 Operation method
Measure 1-2 ml of the sample and inject it into a test tube, add an equal amount of resin powder and carbon disulfide saturated solution, shake well, add 1 ml of concentrated nitric acid, and shake vigorously. If it is pure tea seed oil, there will be no color, and the acid solution in the lower layer of the test tube is clear like water. If other vegetable oils are present, purple or red will appear, but the color will disappear soon. 15 Detection of hemp seed oil
Take 10 μl of the sample to be tested and the control sample (known to contain hemp seed oil) and spot them on a silica gel G thin layer plate (activated at 105℃ for 30 minutes). If spotting is difficult, dilute the sample 5 times with benzene and spot 10-20 μl each. Use benzene as the developing agent and 0.15% fast blue salt β solution as the color developer (prepare it before use). If red spots appear on the sample to be tested, and the color tone and ratio shift value are consistent with those of the control sample, it is positive. Flax oil and sesame oil also show red color, but the migration value is smaller than that of hemp seed oil. Additional notes:
This standard was proposed by the Ministry of Commerce of the People's Republic of China. This standard was drafted by the Grain Storage and Transportation Bureau of the Ministry of Commerce. The main drafters of this standard are Gao Xiuwu, Yang Haoran, Wu Yanxia, and Lv Guifen. This standard was compiled by Ha Junshan and Lin Xianming. Issued by the National Bureau of Standards on November 2, 1985
Implementation on July 1, 1986001g.
11.2 Reagents
Potassium hydroxide ethanol solution: 80ml of 25% KOH (specific gravity 1.24) solution, dilute to 1000ml with 95% ethanol;11.2.2
Lead acetate solution: 50g lead acetate mixed with 5ml90% acetic acid, dilute to 1000ml with 80% ethanol;0.2N iodine ethanol solution: 5.07g sublimated iodine dissolved in 200ml95% ethanol. Prepare immediately before use;Ethanol acetic acid mixture: 1 part 95% ethanol mixed with 1 part 96% acetic acid;11.2.570% ethanol;
11.2.60.1N sodium thiosulfate solution;
11.2.7 Starch indicator.
11.3 Operation method
Weigh 0.500-0.510g of the mixed sample and inject it into a 150ml conical flask, add 50ml potassium hydroxide ethanol solution, connect
condenser, place it in a water bath and heat for 1h, add 20ml lead acetate solution and 1ml90% acetic acid to the saponified solution, and then continue to heat until the lead salt is dissolved. Remove the conical flask, wait for the solution to cool slightly, add 3ml of water, shake the spoon, place it in a 20℃ incubator and let it stand for 14h, transfer the precipitate to a glass filter crucible, and wash the conical flask and precipitate with 12ml of 70% ethanol at 20℃ several times. Move the crucible to the iodine value bottle, dissolve the precipitate into the iodine value bottle with 20ml of hot ethanol and acetic acid mixture, and then wash it with 10ml of hot ethanol and acetic acid mixture. Pipette 20ml of 0.2N iodine ethanol solution into the iodine value bottle, shake well, add 200ml of water immediately, shake well again, and let it stand in the dark for 1h. Then titrate with 0.1N sodium thiosulfate solution until the solution turns light yellow, add 1ml starch indicator, shake well, and continue titrating until the blue color disappears. At the same time, use 30ml of ethanol and acetic acid mixture for blank test. 11.4 Calculation of results
Erucic acid content is calculated according to the following formula:
(V1-V2)× N × 0.169
Erucic acid (%)
Where: V1 is the volume of sodium thiosulfate solution used for blank test, ml; V2 is the volume of sodium thiosulfate solution used for sample, ml; N is the equivalent concentration of sodium thiosulfate solution;
0.169 is the number of milligrams of erucic acid equivalent to each milligram equivalent of sodium thiosulfate: W is the weight of sample, g.
The allowable difference between the two test results shall not exceed 0.2%. The average shall be the test result. The test result shall be rounded to the first decimal place.
12 Detection of lard in vegetable oil
According to the different shapes of various oil crystals, lard is detected by microscopic examination. 12.1 Instruments and appliances
12.1.1 Test tube: 20ml;
12.1.2 Refrigerator,
12.1.3 Microscope: 400 times;
12.1.4 Glass tube: inner diameter 3mm.
12.2 Reagents
12.2.1 Ether
12.2.2 Cotton wool
12.3 Operation method
Take 3 20ml test tubes, wash and dry them, and number them 1, 2, and 3. Add 10ml of ether to each. Add 2 ml of the oil sample to be tested to tube 1; add 1 ml of melted lard to tube 2; add 2 ml of pure oil to be tested to tube 3. Plug the mouths of the three tubes with absorbent cotton and place them in a refrigerator or ice water. After the crystals precipitate (about 10 hours), observe under a microscope. No crystals should precipitate in tube 3 (raisin oil); white crystals precipitate in tube 2; if there is lard in tube 1, white crystals will also precipitate, and the amount of precipitation is proportional to the lard content. Identification of lard crystals: drop a drop of pure oil on a glass slide, use a glass tube with an inner diameter of 3 mm to absorb half a drop of crystals and add it to the oil drop, add a cover slide and observe under a microscope. The lard crystals are slender or needle-shaped. 13 Detection of tea oil
13.1 Instruments and utensils
13.1.1 Test tube: 50ml;
13.1.2 Constant temperature water bath;
13.1.3 Measuring cylinder, etc.
13.2 Reagents
13.2.1 Acetic anhydride;
13.2.2 Dichloromethane;
13.2.3 Concentrated sulfuric acid;
13.2.4 Anhydrous ether.
13.3 Operation method
Measure 0.8ml of acetic anhydride, 1.5ml of dichloromethane and 0.2ml of concentrated sulfuric acid and inject them into a test tube. After mixing, cool to room temperature. Add 7 drops of
sample (about 0.22g) to the tube, mix and cool. If the solution is turbid, add acetic anhydride dropwise, shaking while dropping until it suddenly becomes clear. After standing for 5 minutes, measure 10ml of anhydrous acetaldehyde and inject it into the color developing solution. Immediately invert it once to mix. Within about 1 minute, the tea oil will produce brown, then turn dark red, and slowly fade within a few minutes. After adding anhydrous ether, olive oil is initially green, slowly turns brown-gray, and sometimes goes through a light red process in the middle. The mixed oil of olive oil and tea oil shows the color reaction of tea oil, and the color depth is proportional to the tea oil content. If colorimetric quantification is required, after the above method is allowed to stand for 5 minutes, place the test tube in an ice-water bath for 1 minute, inject 10 ml of anhydrous ether cooled by ice water
and mix, and then place it in the ice-water bath for 1 to 5 minutes. The color depth can reach the highest peak. Use a sample with a known tea oil content and the sample to be tested, and select the deepest red for colorimetric quantification. 14 Tea Oil Purity Test
14.1 Instruments and Utensils
Test tubes, measuring cylinders, etc.
14.2 Reagents
14.2.1 Resin powder carbon disulfide saturated solution: Weigh 2 to 3 g of pure resin powder and dissolve it in 100 ml of carbon disulfide. Shake it vigorously for a few minutes to make it a saturated solution. Filter it with filter paper and set aside. 14.2.2 Concentrated nitric acid.
14.3 Operation method
Measure 1-2 ml of the sample and inject it into a test tube, add an equal amount of resin powder and carbon disulfide saturated solution, shake well, add 1 ml of concentrated nitric acid, and shake vigorously. If it is pure tea seed oil, there will be no color, and the acid solution in the lower layer of the test tube is clear like water. If other vegetable oils are present, purple or red will appear, but the color will disappear soon. 15 Detection of hemp seed oil
Take 10 μl of the sample to be tested and the control sample (known to contain hemp seed oil) and spot them on a silica gel G thin layer plate (activated at 105℃ for 30 minutes). If spotting is difficult, dilute the sample 5 times with benzene and spot 10-20 μl each. Use benzene as the developing agent and 0.15% fast blue salt β solution as the color developer (prepare it before use). If red spots appear on the sample to be tested, and the color tone and ratio shift value are consistent with those of the control sample, it is positive. Flax oil and sesame oil also show red color, but the migration value is smaller than that of hemp seed oil. Additional notes:
This standard was proposed by the Ministry of Commerce of the People's Republic of China. This standard was drafted by the Grain Storage and Transportation Bureau of the Ministry of Commerce. The main drafters of this standard are Gao Xiuwu, Yang Haoran, Wu Yanxia, and Lv Guifen. This standard was compiled by Ha Junshan and Lin Xianming. Issued by the National Bureau of Standards on November 2, 1985
Implementation on July 1, 1986001g.
11.2 Reagents
Potassium hydroxide ethanol solution: 80ml of 25% KOH (specific gravity 1.24) solution, dilute to 1000ml with 95% ethanol;11.2.2
Lead acetate solution: 50g lead acetate mixed with 5ml90% acetic acid, dilute to 1000ml with 80% ethanol;0.2N iodine ethanol solution: 5.07g sublimated iodine dissolved in 200ml95% ethanol. Prepare immediately before use;Ethanol acetic acid mixture: 1 part 95% ethanol mixed with 1 part 96% acetic acid;11.2.570% ethanol;
11.2.60.1N sodium thiosulfate solution;
11.2.7 Starch indicator.
11.3 Operation method
Weigh 0.500-0.510g of the mixed sample and inject it into a 150ml conical flask, add 50ml potassium hydroxide ethanol solution, connect
condenser, place it in a water bath and heat for 1h, add 20ml lead acetate solution and 1ml90% acetic acid to the saponified solution, and then continue to heat until the lead salt is dissolved. Remove the conical flask, wait for the solution to cool slightly, add 3ml of water, shake the spoon, place it in a 20℃ incubator and let it stand for 14h, transfer the precipitate to a glass filter crucible, and wash the conical flask and precipitate with 12ml of 70% ethanol at 20℃ several times. Move the crucible to the iodine value bottle, dissolve the precipitate into the iodine value bottle with 20ml of hot ethanol and acetic acid mixture, and then wash it with 10ml of hot ethanol and acetic acid mixture. Pipette 20ml of 0.2N iodine ethanol solution into the iodine value bottle, shake well, add 200ml of water immediately, shake well again, and let it stand in the dark for 1h. Then titrate with 0.1N sodium thiosulfate solution until the solution turns light yellow, add 1ml starch indicator, shake well, and continue titrating until the blue color disappears. At the same time, use 30ml of ethanol and acetic acid mixture for blank test. 11.4 Calculation of results
Erucic acid content is calculated according to the following formula:
(V1-V2)× N × 0.169
Erucic acid (%)
Where: V1 is the volume of sodium thiosulfate solution used for blank test, ml; V2 is the volume of sodium thiosulfate solution used for sample, ml; N is the equivalent concentration of sodium thiosulfate solution;
0.169 is the number of milligrams of erucic acid equivalent to each milligram equivalent of sodium thiosulfate: W is the weight of sample, g.
The allowable difference between the two test results shall not exceed 0.2%. The average shall be the test result. The test result shall be rounded to the first decimal place.
12 Detection of lard in vegetable oil
According to the different shapes of various oil crystals, lard is detected by microscopic examination. 12.1 Instruments and appliances
12.1.1 Test tube: 20ml;
12.1.2 Refrigerator,
12.1.3 Microscope: 400 times;
12.1.4 Glass tube: inner diameter 3mm.
12.2 Reagents
12.2.1 Ether
12.2.2 Cotton wool
12.3 Operation method
Take 3 20ml test tubes, wash and dry them, and number them 1, 2, and 3. Add 10ml of ether to each. Add 2 ml of the oil sample to be tested to tube 1; add 1 ml of melted lard to tube 2; add 2 ml of pure oil to be tested to tube 3. Plug the mouths of the three tubes with absorbent cotton and place them in a refrigerator or ice water. After the crystals precipitate (about 10 hours), observe under a microscope. No crystals should precipitate in tube 3 (raisin oil); white crystals precipitate in tube 2; if there is lard in tube 1, white crystals will also precipitate, and the amount of precipitation is proportional to the lard content. Identification of lard crystals: drop a drop of pure oil on a glass slide, use a glass tube with an inner diameter of 3 mm to absorb half a drop of crystals and add it to the oil drop, add a cover slide and observe under a microscope. The lard crystals are slender or needle-shaped. 13 Detection of tea oil
13.1 Instruments and utensils
13.1.1 Test tube: 50ml;
13.1.2 Constant temperature water bath;
13.1.3 Measuring cylinder, etc.
13.2 Reagents
13.2.1 Acetic anhydride;
13.2.2 Dichloromethane;
13.2.3 Concentrated sulfuric acid;
13.2.4 Anhydrous ether.
13.3 Operation method
Measure 0.8ml of acetic anhydride, 1.5ml of dichloromethane and 0.2ml of concentrated sulfuric acid and inject them into a test tube. After mixing, cool to room temperature. Add 7 drops of
sample (about 0.22g) to the tube, mix and cool. If the solution is turbid, add acetic anhydride dropwise, shaking while dropping until it suddenly becomes clear. After standing for 5 minutes, measure 10ml of anhydrous acetaldehyde and inject it into the color developing solution. Immediately invert it once to mix. Within about 1 minute, the tea oil will produce brown, then turn dark red, and slowly fade within a few minutes. After adding anhydrous ether, olive oil is initially green, slowly turns brown-gray, and sometimes goes through a light red process in the middle. The mixed oil of olive oil and tea oil shows the color reaction of tea oil, and the color depth is proportional to the tea oil content. If colorimetric quantification is required, after the above method is allowed to stand for 5 minutes, place the test tube in an ice-water bath for 1 minute, inject 10 ml of anhydrous ether cooled by ice water
and mix, and then place it in the ice-water bath for 1 to 5 minutes. The color depth can reach the highest peak. Use a sample with a known tea oil content and the sample to be tested, and select the deepest red for colorimetric quantification. 14 Tea Oil Purity Test
14.1 Instruments and Utensils
Test tubes, measuring cylinders, etc.
14.2 Reagents
14.2.1 Resin powder carbon disulfide saturated solution: Weigh 2 to 3 g of pure resin powder and dissolve it in 100 ml of carbon disulfide. Shake it vigorously for a few minutes to make it a saturated solution. Filter it with filter paper and set aside. 14.2.2 Concentrated nitric acid.
14.3 Operation method
Measure 1-2 ml of the sample and inject it into a test tube, add an equal amount of resin powder and carbon disulfide saturated solution, shake well, add 1 ml of concentrated nitric acid, and shake vigorously. If it is pure tea seed oil, there will be no color, and the acid solution in the lower layer of the test tube is clear like water. If other vegetable oils are present, purple or red will appear, but the color will disappear soon. 15 Detection of hemp seed oil
Take 10 μl of the sample to be tested and the control sample (known to contain hemp seed oil) and spot them on a silica gel G thin layer plate (activated at 105℃ for 30 minutes). If spotting is difficult, dilute the sample 5 times with benzene and spot 10-20 μl each. Use benzene as the developing agent and 0.15% fast blue salt β solution as the color developer (prepare it before use). If red spots appear on the sample to be tested, and the color tone and ratio shift value are consistent with those of the control sample, it is positive. Flax oil and sesame oil also show red color, but the migration value is smaller than that of hemp seed oil. Additional notes:
This standard was proposed by the Ministry of Commerce of the People's Republic of China. This standard was drafted by the Grain Storage and Transportation Bureau of the Ministry of Commerce. The main drafters of this standard are Gao Xiuwu, Yang Haoran, Wu Yanxia, and Lv Guifen. This standard was compiled by Ha Junshan and Lin Xianming. Issued by the National Bureau of Standards on November 2, 1985
Implementation on July 1, 19864 Calculation of results
Erucic acid content is calculated according to the following formula:
(V1-V2)× N × 0.169
Erucic acid (%)
Wherein: V1 Volume of sodium thiosulfate solution used in blank test, ml; V2—Volume of sodium thiosulfate solution used in sample, ml; N Equivalent concentration of sodium thiosulfate solution;
0.169 Number of milligrams of erucic acid equivalent to each milligram equivalent of sodium thiosulfate: W—sample weight, g.
The allowable difference between the results of two tests shall not exceed 0.2%. The average shall be the test result. The test result shall be taken to the first decimal place.
12 Detection of lard in vegetable oil
According to the different shapes of various oil crystals, lard is detected by microscopic examination. 12.1 Instruments and equipment
12.1.1 Test tube: 20ml;
12.1.2 Refrigerator,
12.1.3 Microscope: 400 times;
12.1.4 Glass tube: inner diameter 3mm.
12.2 Reagents
12.2.1 Ether
12.2.2 Absorbent cotton
12.3 Operation method
Wash and dry 3 20ml test tubes, number them 1, 2, and 3, and add 10ml of ether to each. Add 2ml of the oil sample to be tested to tube 1; add 1ml of melted lard to tube 2; and add 2ml of the pure oil to be tested to tube 3. Plug the mouths of the three tubes with absorbent cotton and place them in a refrigerator or ice water. After the crystals precipitate (about 10 hours), observe under a microscope. No crystals should precipitate in tube No. 3 (rice oil); white crystals precipitate in tube No. 2; if there is lard in tube No. 1, white crystals will also precipitate, and the amount of precipitation is proportional to the lard content. Identification of lard crystals: drop a drop of pure oil on a glass slide, use a glass tube with an inner diameter of 3mm to absorb half a drop of crystals and add it to the oil drop, add a cover slide and observe under a microscope. The lard crystals are slender or needle-shaped. 13 Detection of tea seed oil
13.1 Instruments and utensils
13.1.1 Test tube: 50ml;
13.1.2 Constant temperature water bath;
13.1.3 Measuring cylinder, etc.
13.2 Reagents
13.2.1 Acetic anhydride;
13.2.2 Dichloromethane;
13.2.3 Concentrated sulfuric acid;
13.2.4 Anhydrous ether.
13.3 Operation method
Measure 0.8ml of acetic anhydride, 1.5ml of dichloromethane and 0.2ml of concentrated sulfuric acid and inject them into a test tube. After mixing, cool to room temperature. Add 7 drops of
sample (about 0.22g) to the tube, mix well and cool. If the solution becomes turbid, add acetic anhydride dropwise, shaking while dropping until it suddenly becomes clear. After standing for 5 minutes, measure 10ml of anhydrous acetaldehyde and inject it into the color developing solution. Immediately invert it once to mix it. In about 1 minute, the tea seed oil will turn brown, then dark red, and slowly fade in a few minutes. When anhydrous ether is added to olive oil, it is initially green, then slowly turns brown-gray, and sometimes goes through a light red process in the middle. The mixed oil of olive oil and camellia oil shows the color reaction of camellia oil, and the color depth is proportional to the camellia oil content. If colorimetric quantification is required, after the above method is allowed to stand for 5 minutes, the test tube can be placed in an ice water bath for 1 minute, and 10 ml of anhydrous ether cooled by ice water
is injected and mixed. After that, it is still placed in the ice water bath for 1 to 5 minutes. The color depth can reach the highest peak. Use a sample with a known camellia oil content and the sample to be tested, and select the deepest red for colorimetric quantification. 14 Camellia oil purity test
14.1 Instruments and utensils
Test tubes, measuring cylinders, etc.
14.2 Reagents
14.2.1 Saturated solution of resin powder and carbon disulfide: Weigh 2-3g of pure resin powder and dissolve it in 100ml of carbon disulfide. Shake it vigorously for a few minutes to make it a saturated solution. Filter it with filter paper and set aside. 14.2.2 Concentrated nitric acid.
14.3 Operation method
Measure 1-2ml of the sample and inject it into a test tube. Add an equal amount of saturated solution of resin powder and carbon disulfide. After shaking thoroughly, add 1ml of concentrated nitric acid and shake it vigorously again. If it is pure tea seed oil, there will be no color, and the acid solution in the lower layer of the test tube is as clear as water. If other vegetable oils are present, purple or red will appear, but the color will disappear soon. 15 Detection of hemp seed oil
Take 10u1 of the sample to be tested and the control sample (known to contain hemp seed oil) and spot them on a silica gel G thin layer plate (activated at 105℃ for 30min). If it is difficult to spot the sample, dilute the sample 5 times with benzene and spot 10-20μ1 each time. Use benzene as the developing agent and 0.15% fast blue salt β solution (prepare immediately before use) as the color developer. If red spots appear on the sample under test, and the color tone and transfer value are consistent with those of the control sample, it is positive. Linseed oil and sesame oil also appear red, but the transfer value is smaller than that of hemp seed oil. Additional notes:
This standard was proposed by the Ministry of Commerce of the People's Republic of China and was drafted by the Grain Storage and Transportation Bureau of the Ministry of Commerce. The main drafters of this standard are Gao Xiuwu, Yang Haoran, Wu Yanxia, and Lu Guifen. This standard was compiled by Ha Junshan and Lin Xianming. Issued by the National Bureau of Standards on November 2, 1985
Implementation on July 1, 19864 Calculation of results
Erucic acid content is calculated according to the following formula:
(V1-V2)× N × 0.169
Erucic acid (%)
Wherein: V1 Volume of sodium thiosulfate solution used in blank test, ml; V2—Volume of sodium thiosulfate solution used in sample, ml; N Equivalent concentration of sodium thiosulfate solution;
0.169 Number of milligrams of erucic acid equivalent to each milligram equivalent of sodium thiosulfate: W—sample weight, g.
The allowable difference between the results of two tests shall not exceed 0.2%. The average shall be the test result. The test result shall be taken to the first decimal place.
12 Detection of lard in vegetable oil
According to the different shapes of various oil crystals, lard is detected by microscopic examination. 12.1 Instruments and equipment
12.1.1 Test tube: 20ml;
12.1.2 Refrigerator,
12.1.3 Microscope: 400 times;
12.1.4 Glass tube: inner diameter 3mm.
12.2 Reagents
12.2.1 Ether
12.2.2 Absorbent cotton
12.3 Operation method
Wash and dry 3 20ml test tubes, number them 1, 2, and 3, and add 10ml of ether to each. Add 2ml of the oil sample to be tested to tube 1; add 1ml of melted lard to tube 2; and add 2ml of the pure oil to be tested to tube 3. Plug the mouths of the three tubes with absorbent cotton and place them in a refrigerator or ice water. After the crystals precipitate (about 10 hours), observe under a microscope. No crystals should precipitate in tube No. 3 (rice oil); white crystals precipitate in tube No. 2; if there is lard in tube No. 1, white crystals will also precipitate, and the amount of precipitation is proportional to the lard content. Identification of lard crystals: drop a drop of pure oil on a glass slide, use a glass tube with an inner diameter of 3mm to absorb half a drop of crystals and add it to the oil drop, add a cover slide and observe under a microscope. The lard crystals are slender or needle-shaped. 13 Detection of tea seed oil
13.1 Instruments and utensils
13.1.1 Test tube: 50ml;
13.1.2 Constant temperature water bath;
13.1.3 Measuring cylinder, etc.
13.2 Reagents
13.2.1 Acetic anhydride;
13.2.2 Dichloromethane;
13.2.3 Concentrated sulfuric acid;
13.2.4 Anhydrous ether.
13.3 Operation method
Measure 0.8ml of acetic anhydride, 1.5ml of dichloromethane and 0.2ml of concentrated sulfuric acid and inject them into a test tube. After mixing, cool to room temperature. Add 7 drops of
sample (about 0.22g) to the tube, mix well and cool. If the solution becomes turbid, add acetic anhydride dropwise, shaking while dropping until it suddenly becomes clear. After standing for 5 minutes, measure 10ml of anhydrous acetaldehyde and inject it into the color developing solution. Immediately invert it once to mix it. In about 1 minute, the tea seed oil will turn brown, then dark red, and slowly fade in a few minutes. When anhydrous ether is added to olive oil, it is initially green, then slowly turns brown-gray, and sometimes goes through a light red process in the middle. The mixed oil of olive oil and camellia oil shows the color reaction of camellia oil, and the color depth is proportional to the camellia oil content. If colorimetric quantification is required, after the above method is allowed to stand for 5 minutes, the test tube can be placed in an ice water bath for 1 minute, and 10 ml of anhydrous ether cooled by ice water
is injected and mixed. After that, it is still placed in the ice water bath for 1 to 5 minutes. The color depth can reach the highest peak. Use a sample with a known camellia oil content and the sample to be tested, and select the deepest red for colorimetric quantification. 14 Camellia oil purity test
14.1 Instruments and utensils
Test tubes, measuring cylinders, etc.
14.2 Reagents
14.2.1 Saturated solution of resin powder and carbon disulfide: Weigh 2-3g of pure resin powder and dissolve it in 100ml of carbon disulfide. Shake it vigorously for a few minutes to make it a saturated solution. Filter it with filter paper and set aside. 14.2.2 Concentrated nitric acid.
14.3 Operation method
Measure 1-2ml of the sample and inject it into a test tube. Add an equal amount of saturated solution of resin powder and carbon disulfide. After shaking thoroughly, add 1ml of concentrated nitric acid and shake it vigorously again. If it is pure tea seed oil, there will be no color, and the acid solution in the lower layer of the test tube is as clear as water. If other vegetable oils are present, purple or red will appear, but the color will disappear soon. 15 Detection of hemp seed oil
Take 10u1 of the sample to be tested and the control sample (known to contain hemp seed oil) and spot them on a silica gel G thin layer plate (activated at 105℃ for 30min). If it is difficult to spot the sample, dilute the sample 5 times with benzene and spot 10-20μ1 each time. Use benzene as the developing agent and 0.15% fast blue salt β solution (prepare immediately before use) as the color developer. If red spots appear on the sample under test, and the color tone and transfer value are consistent with those of the control sample, it is positive. Linseed oil and sesame oil also appear red, but the transfer value is smaller than that of hemp seed oil. Additional notes:
This standard was proposed by the Ministry of Commerce of the People's Republic of China and was drafted by the Grain Storage and Transportation Bureau of the Ministry of Commerce. The main drafters of this standard are Gao Xiuwu, Yang Haoran, Wu Yanxia, and Lu Guifen. This standard was compiled by Ha Junshan and Lin Xianming. Issued by the National Bureau of Standards on November 2, 1985
Implementation on July 1, 19861 Resin powder carbon disulfide saturated solution: Weigh 2-3g pure resin powder and dissolve it in 100ml carbon disulfide, shake it vigorously for a few minutes to make it a saturated solution, filter it with filter paper and set aside. 14.2.2 Concentrated nitric acid.
14.3 Operation method
Measure 1-2ml of the sample and inject it into a test tube, add an equal amount of resin powder carbon disulfide saturated solution, shake it thoroughly, add 1ml of concentrated nitric acid, and shake it vigorously again. If it is pure tea seed oil, there will be no color, and the acid solution in the lower layer of the test tube is clear like water. If other vegetable oils are present, purple or red will appear, but the color will disappear soon. 15 Detection of hemp seed oil
Take 10u1 of the sample to be tested and the control sample (known to contain hemp seed oil) and spot them on the silica gel G thin layer plate (activated at 105℃ for 30min). If spotting is difficult, the sample can be diluted 5 times with benzene and 10-20μ1 can be spotted on each. The developing agent is benzene and the color developer is 0.15% fast blue salt β solution (prepare immediately before use). If red spots appear on the sample under test, and the color tone and transfer value are consistent with those of the control sample, it is positive. Linseed oil and sesame oil also appear red, but the transfer value is smaller than that of hemp seed oil. Additional notes:
This standard was proposed by the Ministry of Commerce of the People's Republic of China and was drafted by the Grain Storage and Transportation Bureau of the Ministry of Commerce. The main drafters of this standard are Gao Xiuwu, Yang Haoran, Wu Yanxia, and Lu Guifen. This standard was written by Ha Junshan and Lin Xianming. Issued by the National Bureau of Standards on November 2, 1985
Implementation on July 1, 19861 Resin powder carbon disulfide saturated solution: Weigh 2-3g pure resin powder and dissolve it in 100ml carbon disulfide, shake it vigorously for a few minutes to make it a saturated solution, filter it with filter paper and set aside. 14.2.2 Concentrated nitric acid.
14.3 Operation method
Measure 1-2ml of the sample and inject it into a test tube, add an equal amount of resin powder carbon disulfide saturated solution, shake it thoroughly, add 1ml of concentrated nitric acid, and shake it vigorously again. If it is pure tea seed oil, there will be no color, and the acid solution in the lower layer of the test tube is clear like water. If other vegetable oils are present, purple or red will appear, but the color will disappear soon. 15 Detection of hemp seed oil
Take 10u1 of the sample to be tested and the control sample (known to contain hemp seed oil) and spot them on the silica gel G thin layer plate (activated at 105℃ for 30min). If spotting is difficult, the sample can be diluted 5 times with benzene and 10-20μ1 can be spotted on each. The developing agent is benzene and the color developer is 0.15% fast blue salt β solution (prepare immediately before use). If red spots appear on the sample under test, and the color tone and transfer value are consistent with those of the control sample, it is positive. Linseed oil and sesame oil also appear red, but the transfer value is smaller than that of hemp seed oil. Additional notes:
This standard was proposed by the Ministry of Commerce of the People's Republic of China and was drafted by the Grain Storage and Transportation Bureau of the Ministry of Commerce. The main drafters of this standard are Gao Xiuwu, Yang Haoran, Wu Yanxia, and Lu Guifen. This standard was written by Ha Junshan and Lin Xianming. Issued by the National Bureau of Standards on November 2, 1985
Implementation on July 1, 1986
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