NF Monographs: Olive Oil

Olive Oil

» Olive Oil is the fixed oil obtained from the ripe fruit of Olea europaea Linné (Fam. Oleaceae).

Packaging and storage— Preserve in tight containers, and prevent exposure to excessive heat.

: between 0.910 and 0.915.

Cottonseed oil— Mix 5 mL in a test tube with 5 mL of a mixture of equal volumes of amyl alcohol and a 1 in 100 solution of sulfur in carbon disulfide, warm the mixture carefully to expel the carbon disulfide, and immerse the test tube to one-third of its length in a boiling, saturated solution of sodium chloride for 2 hours: the mixture develops no reddish color.

Peanut oil— Saponify 10 g by heating for 1 hour under a reflux condenser with 80 mL of alcoholic potassium hydroxide TS. Add phenolphthalein TS, neutralize with 1 N acetic acid, and wash the solution into 120 mL of boiling lead acetate TS contained in a conical flask. Boil the mixture for 1 minute, and cool by immersing the flask in cold water, rotating the contents occasionally to cause the precipitate to adhere to the walls of the flask. Decant the liquid, wash the precipitate with cold water to remove the excess lead acetate, and then wash with 90 percent (by volume) alcohol. Add 100 mL of ether, stopper the flask, and allow to stand until the precipitate is disintegrated. Connect the flask to a reflux condenser, boil for 5 minutes, cool to about 15

, and allow to stand overnight. Filter, and thoroughly wash the precipitate with ether. With the use of a jet of ether, transfer the precipitate to a 500-mL separator, alternating the jet of ether with 3 N hydrochloric acid at the end if any of the precipitate adheres to the filter paper. Add sufficient 3 N hydrochloric acid to make the total acid layer measure about 100 mL, and add sufficient ether to make the ether layer measure about 100 mL. Shake the mixture vigorously for several minutes, allow the layers to separate, draw off the acid layer, and wash the ether once by shaking with 50 mL of 3 N hydrochloric acid and finally with several portions of water until the last washing is not acid to methyl orange TS. Transfer the ether solution to a dry flask, evaporate the ether, add a small amount of dehydrated alcohol, and evaporate on a steam bath to dryness. Dissolve the residue of dry fatty acids by warming with 60 mL of 90 percent (by volume) alcohol, slowly cool the solution to 15

while shaking frequently, and allow the solution to stand at 15

for 30 minutes: no crystals separate from the solution.

Sesame oil— Mix 10 mL with 10 mL of hydrochloric acid, add 0.1 mL of a 1 in 50 solution of furfural in alcohol, and shake the mixture vigorously for 15 seconds: no pink to crimson color appears in the acid layer when the emulsion breaks. If any color appears in the acid layer, add 10 mL of water, and again shake the mixture vigorously: in the absence of sesame oil any pink color is evanescent.

Teaseed oil— In a dry, 18- × 150-mm test tube place 0.8 mL of acetic anhydride, 1.5 mL of chloroform, and 0.2 mL of sulfuric acid, mix, and cool in a water bath to 25

. Add about 200 mg of Olive Oil (about 7 drops), mix, and cool to 25

. If the solution is cloudy, add acetic anhydride, dropwise, shaking after each addition, until the solution suddenly clears. Allow the mixture to remain in the water bath for 5 minutes: it shows a green color by both reflected and transmitted light. Add 10 mL of absolute ether, and mix by inverting the tube: the initial green color fades to a brownish gray. (Before the dilution with ether, the presence of teaseed oil will cause a brown color to appear by transmitted light, and after the dilution, a transient red color.)

Solidification range of fatty acids

401

— The dry, mixed fatty acids of it solidify between 17

and 26

Free fatty acids

401

— The free fatty acids in 10 g require for neutralization not more than 5.0 mL of 0.10 N sodium hydroxide.

Iodine value

401

: between 79 and 88.

Saponification value

401