282.-284. The Lemon Products.
282. Limonis Succus. - The Juice. Lemon Juice.
282. LIMONIS SUCCUS—THE JUICE.—LEMON JUICE (Succus Citri, N. F.). The freshly expressed juice of the ripe fruit of Cit'rus medica Linné (C. limonum Risso, U.S.P. 1900). A slightly turbid, yellowish liquid having the odor of lemon, due to the presence of some of the volatile oil from the rind; taste acid, often slightly bitter. It contains about 7 per cent. of free citric acid, also phosphoric and malic acids. Refrigerant and antiscorbutic; used in the form of lemonade, or in effervescing draughts. Dose: 1 fl. oz. (30 mils) .
Lemon juice should contain from 7 to 9 per cent. of citric acid. It should be free from added preservatives; preserved by sterilization. For tests see U.S.P. VIII. Lemon juice contains from 0.5 to 1 percent. of gum and sugar.
283. LIMONIS CORTEX—THE RIND.—LEMON PEEL. The undried outer rind of the ripe fruit of Citrus medica Linné (C. limonum. Risso, U.S.P. IX), removed by grating. The fruit comes from the Mediterranean and tropical regions (see Orange). The outer surface is of a light yellow color and ruggedly glandular from the oil-cells; odor fragrant; taste aromatic and bitterish.
Microscopically, the rind of the lemon resembles that of the orange.
Powder.—Microscopical elements of: See Part iv, Chap. I, B.
CONSTITUENTS.—A pale yellow volatile oil (sp. gr. 0.87) consisting mainly of hydrocarbons, citrene (C10H16), cymene (C10H14), also citral (C10H16O), and a compound ether. Hesperidin (C22H26O12), a bitter principle, produces with ferric salts a black color.
Used as a flavoring agent.
Tinctura Limonis Corticis (50 per cent.).
284.—OLEUM LIMONIS.—OIL OF LEMON PEEL, OR RIND. A volatile oil obtained by expression from the fresh lemon peel. It is a pale yellow, limpid liquid, having a lemon taste and a fragrant odor. It should be protected from light in well-stoppered bottles. Oil of citral, used in perfumery, is obtained from Cit'rus med'ica Risso, a large oblong fruit with rough surface-known in England as the citron.
Oil of lemon consists of two isomeric oils, chiefly citrene or limonine, C10H16, with citral (an aldehyde) and a crystalline product which fuses at 143° to 144°C. (289° to 291°F.), colored yellow by H2SO4, and green by HNO3. Used principally as a flavor assayed by the official process not less than 4 per cent. of the aldehydes from oil of lemon calculated as citral.
ADULTERATION OF THE OIL OF LEMON.—It is adulterated with the volatile oil of other fruits of the genus Citrus. These are difficult to detect, odor and taste must be chiefly relied upon.
- Spiritus Aurantii Compositus (5 per cent.).
- Spiritus Amonniae Aromaticus, Dose: 30 drops (2 Mils).