Peach Oil

PEACH OIL (Oleum Persicarum), a fatty oil obtained by cold pressing from the seeds of the peach (Prunus persica, family Rosaceae - Amygdaleae) and the apricot (Prunus armenica, family Rosaceae-Amygdaleae). The seeds contain up to 40% oil. Peach oil is not included in the latest 7th Pharmacopoeia of the USSR, but it is used in medicine in all cases where almond oil was previously used, and it can be said to have completely supplanted the latter. Peach oil is a light yellow, odorless, delicate-tasting oil that does not solidify and does not precipitate solid fats even at -10°. The physical and chemical constants of peach oil coincide (within the limits of their fluctuation) with the constants for almond and apricot oil (see Fats, table). Medicinal peach oil must withstand the following purity tests. A mixture of 2 cm³ of peach oil with 10 cm³ of nitric acid (specific gravity 1.14-1.15) and 1 g of sodium nitrite, added in small quantities, must, upon standing undisturbed in a cool place for 4-10 hours, solidify into a solid mass—the elaidin test (so-called drying vegetable oils and mineral oils do not yield a solid mass). 4 g of peach oil are saponified with 50 cm³ of a semi-normal alcoholic solution of caustic potash in a flask on a water bath with a reflux condenser; 15 drops of a 1% alcoholic solution of phenolphthalein are added to the resulting soap solution, and then hydrochloric acid is added dropwise until the red color disappears; the mixture, cooled to 15°, is filtered after 10 minutes, 20 cm³ of the filtrate are placed for 1/2 hour in water at a temperature of 9 to 10°; the filtrate must not become cloudy or produce a precipitate; cloudiness or a precipitate will indicate an admixture of peanut oil or large quantities of cottonseed or sesame oil. The soap solution remaining from the determination of unsaponifiable substances in peach oil is mixed with an excess of hydrochloric acid, and the separated fatty acid (pure peach oil yields almost pure oleic acid in this process) is washed with water and then dried; the resulting fatty acid must not become cloudy within one hour at room temperature, and a mixture of 1 part of it with 1 part of alcohol must remain transparent at room temperature and not become cloudy upon the addition of another 1 part of alcohol; cloudiness or a precipitate will indicate the presence of foreign (other than almond) vegetable oils, or vaseline oil. Both peach oil and apricot oil, unlike almond oil, produce a red or yellow-red coloration when 1 cm³ of peach or apricot oil is shaken with a mixture of 2 cm³ of 50% sulfuric acid and 1 cm³ of fuming nitric acid. Peach oil is used on a par with almond oil: in Emulsio oleosa, in Ol. Camphoratum for subcutaneous injections, and in Unguentum leniens. Peach oil is used in medicine where a delicate, non-irritating, and easily absorbed oil is required. Peach oil is rarely encountered on the market, and apricot oil is usually sold under the name "peach oil."