what is the iodine value range of sesame oil? International standards? The iodine value of sesame oil is 16, which belongs to semi-drying oil. According to iodine price, it can be divided into: drying oil, iodine price >; 17, such as linseed oil and tung oil; Semi-drying oil, iodine value 1 ~ 17, such as soybean oil, rapeseed oil, sesame oil, sunflower oil, etc. Non-drying oil, iodine price <: 1, such as coconut oil, palm oil, tallow oil, lacquer oil, etc. This standard refers to the international standard ISO 3961: 1989 (Animal and vegetable fats and oils-determination of iodine value). 1. Definition of iodine value: The quality of iodine absorbed by the sample under the operating conditions specified in the standard is expressed in grams of iodine absorbed per 1g sample. Second, the principle of dissolving the sample in the solvent and adding WIJS reagent, adding potassium iodide and water after a specified time, and titrating the separated iodine with sodium thiosulfate solution. III. Reagents and solutions 1. Potassium iodide solution (1g/L) without iodate and free iodine 2. Starch solution: mix 5g of soluble starch in 3ml of water, add this mixed solution and boil it in 1ml of boiling water for 3 minutes and cool it 3. Sodium thiosulfate standard solution (.1mol/L): Prepare and calibrate according to GB549. Use within 7 days after calibration. 4. Solvent: mixed solution of cyclohexane and glacial acetic acid with equal volume. 5. Reagent: acetic acid solution containing iodine chloride. Weigh 9g of iodine trichloride and dissolve it in the mixed solution of 7ml glacial acetic acid and 3ml of cyclohexane, take 5ml of the above solution, add 5ml of potassium iodide solution (3.1) and 3ml of water, and use a few drops of starch solution (3.2) as an indicator. Titrate the separated iodine with .1mol/L sodium thiosulfate standard solution (3.3), and the titration volume is V1 GB/T15687 Preparation of oil sample: GB549 General rules for inspection of grain, oil and vegetable oil, add 1g pure iodine to the reagent to completely dissolve it, and titrate it as above. Get V2. V2/V1 should be greater than 1.5, otherwise a little pure iodine can be added until V2/V1 slightly exceeds 1.5. After the solution is allowed to stand, the supernatant is poured into a brown reagent bottle with a plug. Store away from light, this solution can be stored for several months at room temperature. Weighing samples 1. The quality of samples varies according to the estimated iodine price, as shown in the following table. Estimate the quality of iodine valence sample g <: 5 3.5-2 1. 21-5 .4 51-1 .2 11-15 .13 151-2 .12. Put the sample into a 5ml conical flask and add 2ml solvent (3.4) to dissolve the sample. Accurately add 25mlWIJS reagent (3.5), cover the stopper, shake well and place the conical flask in the dark. Similarly, solvent and reagent were used to prepare blank but no sample was added. The sample conical flask with iodine value below 15 should be placed in the dark for 1 hour, and the substances with iodine value above 15 and those that have been aggregated or oxidized to a considerable extent should be placed in the dark for 2 hours. 3. Determination: At the end of the reaction time, add 2ml of potassium iodide solution (3.1) and 15ml of water to titrate to light yellow with calibrated sodium thiosulfate standard solution (3.3), and add a few drops of starch solution (3.2) to continue the titration until the blue color just disappears after violent shaking. 4. Determination times: the same sample is measured twice. 5. Calculation results 1. When the iodine value is expressed in grams of iodine absorbed per 1g sample, it will decrease. Iodine value (L. V) = 12.69 C (V1-V2)/m where: C-the calibrated concentration of sodium thiosulfate solution mol/Lv1-the volume of sodium thiosulfate standard solution used in blank test MLV2-the volume of sodium thiosulfate standard solution used for determination MLM-the mass of sample g 2, when the parallel determination results meet the requirements of allowable difference, the arithmetic mean value is taken as the result 3. The allowable difference of the two determination results.