Lemon Oil

#### Lemon Oil. Next to sweet orange oil, the oil of lemon peel is the most important citrus oil. It is produced by expression (by hand or machine) of the ripe lemon peel after the juice has been removed from the fruit (machine pressing or sponge pressing of the peel), or it can be expressed prior to removal of the pulp and juice (ecuelle method of oil extraction). The various methods of expressing citrus oils have been discussed comprehensively in recent literature and will not be dealt with in this work. **Lemon Oil, **Distilled is an unimportant item in respect to flavor and perfume creation. Even steam distillation of chopped lemon peel under partial vacuum does not lead to a useful lemon oil. Certain quantities of distilled lemon oil are regularly offered from the producers of concentrated lemon juice (compare distilled sweet orange oil). The most modern and highly mechanized processing of lemons and other citrus fruits take place in California and Florida (U.S. A.) and on the island of Cyprus. **Lemon**** ****Oil, Expressed**, is produced in California, Cyprus, Italy, Guinea, Brazil, Tunisia, Israel, Mexico, Jamaica, India, Pakistan, Spain, China, Australia, Union of South Africa, and in several other countries where the tree, **Citrus Limomum**, is cultivated. The lemon tree is probably a native of East India and Burma, and it arrived in Europe with the returning crusaders in the 12th century. It is also known that Columbus brought along lemon and orange seeds on his second voyage to Hispaniola in 1493, thus founding the world’s largest lemon industry (California, late in the 19th century). California is the largest producer of machine- pressed lemon oil, followed by Cyprus Island. Italy probably exports more lemon oil than does the island of Cyprus, but the Italian oils are partly machine pressed, partly hand pressed; unfortunately, a large portion of the Italian oils are of such poor grade that a dilution or adulteration, cutting, etc. with terpenes, citral, etc. is obvious. The author has observed no such mistreatment of lemon oil from Cyprus. Guinea is the world’s largest producer of hand-pressed lemon oil (by the spoon-ecuelle method) but this country cannot compete with the other producers in quantity. See also Orange Oil, Sweet, from Guinea. Most of the other countries produce lemon oil only for local consumption. The total annual production of expressed lemon oil exceeded 1000 metric tons in the 1950’s and was estimated at 1200 to 1300 metric tons in 1959. **Expressed Lemon Oil **is a yellow to greenish yellow or pale yellow mobile liquid of very light, fresh and sweet odor, truly reminiscent of the ripe peel. No turpentine-like, harsh-terpene notes should be detectable on a perfume blotter. Good oils retain their fresh lemon odor practically unchanged on a blotter until there is no odor left at all. The odor of lemon oil is not very lasting, but the tenacity varies considerably with the method of expression. See below notes on the evaporation residue. The oil should be clear, not hazy or turbid, and it should not show resinous deposits. It has become customary to treat lemon oil (and other citrus oils) with an antioxidant in order to retard the deterioration of the oil when the original container has been opened, and the oil has been exposed to air, daylight and—in particular—moisture or water. Old-fashioned stabilizers, such as absolute alcohol (5% addition) or olive oil, are not without effect, but modern antioxidants can be used with good effect at a much lower level (combination-antioxidants at about 0.005%). This treatment is preferable as it will not affect any later flavor or perfume work with the oil. Most antioxidants are without effect unless the oil is waterfree. When stored in a dark place at cool and constant temperature in a dry, ironfree container with little or no atmospheric air above the surface (carbon dioxide, nitrogen or other inert gas can be injected to replace the air in the container), lemon oil can be stored for years without losing its fresh and pleasant odor and flavor. The outstanding keeping qualities of Cyprus lemon oil could be due to the ultramodern processing by which the oil is very effectively freed not only of pulp and albedo particles, but also of water (in high-speed silver-lined centrifuges). It is a known fact that the old-fashioned sponge method, now almost abandoned in Italy, yields oils with very low evaporation residue, while machines will produce oils with either high residue (Italian machine pressed oils) or low residue (Californian machine pressed oils). However, the content of non-volatile matter (= evaporation residue) is not a very good indication of the quality of the oil since lemon oil residues, sesquiterpenes, etc., are commercially available from the producers of sesquiterpeneless oils. A thorough olfactory and organoleptic examination of the oils is the only safe means of evaluation. **Expressed Lemon Oil **is used in perfumes and flavors for its refreshing, sweet-fruity note. It is one of the more important ingredients in the old-fashioned citrus-type of colognes, in “Eau de Verveine” and other toilet waters, lotions, aerosol sprays, etc. It finds general application as a freshener and topnote ingredient in countless perfume types. **Lemon Oil **blends well with other citrus oils, with lavender oil, lavandin, elemi, labdanum, petitgrain, neroli, etc. and among the most common fixatives for lemon oil are coumarin, vanillin, cinnamates, elemi resinoid, oakmoss products, araucaria oil, etc. Lemon oil is often accompanied by aliphatic aldehydes as modifiers for the lemon topnote. In flavors, **Concentrated**** ****Lemon**** ****Oils**** **or **Sesquiterpeneless**** ****Lemon**** ****Oils**** **(see these monographs) are preferred since a high terpene content will cause problems with regard to solubility, and will tend to produce harsh notes when the flavor is incorporated in moist or aqueous preparations (carbonated drinks, candy, sherbet ice, etc.). The masking effect of **Lemon Oil **is well known from everyday life: lemon quarters or halves are often served along with fish and other seafood. The fresh lemon-odor completely masks the amine- like odors of the seafood. This masking effect is due to the minute amounts of peel oil, which inevitably are squirted upon the food, when the lemon is squeezed. The juice plays a significant role in the masking job: citric acid from the juice neutralizes the amines in the seafood, thereby eliminating part of the obnoxious odor. With vanillin and other synthetic flavor ingredients, lemon oil forms the base of the old-fashioned “custard” flavor, and certain types of hard candy are flavored exclusively with lemon oil in acid media. In view of the general acceptability and popularity of lemon as a flavor type, and considering the very wide variations in quality of various lemon oils, it is extremely difficult to give an approximate use level for lemon oil in flavors. The concentration would generally be from 1.50 mg% to 10.0 mg% in aqueous media with about 12% cane sugar and 0.05 to 0.08% citric acid or equivalent amount of other edible acid (tartaric acid, lactic acid, etc.). In a similar medium, the Minimum Perceptible is 0.50 mg% to 1.00 mg% for a good and fresh, commercial quality of lemon oil. Lemon oil in high dilution does not give a true impression of the peel of the lemon fruit unless it is accompanied by a certain amount of acid. The acid taste seems so inseparably bound up with the lemon flavor that we subconsciously expect acidity along with the odor and flavor of lemon. For further discussion of lemon oils in flavors, see **Lemon Oil,**** ****Concentrated **and **Lemon Oil, Sesquiterpeneless**. **Lemon Oil, Expressed**, is frequently adulterated. Distilled lemon oil (see above in this monograph), lemon terpenes (from deterpenation), d-limonene (natural isolate or synthetic from pinene), synthetic dipentene, synthetic or isolated citral, and numerous other synthetic materials are used to “reconstitute” a poor lemon oil or a lemon oil with a low citral content, etc. Unfortunately, these cutting materials are readily available in Italy, and heavy fluctuations in the lemon oil price (particularly outside of the U.S.A.) have caused occasional increases in the cutting and adulteration of this essential oil to a point where consumers have been tempted to judge all Italian lemon oils under one mutual designation. The consumers or factories who carry out deterpenation of lemon oils can judge each oil in this respect. There are still some outstandingly good Italian lemon oils to be found and used by those who really know good quality from poor. The “scientific” adulteration of lemon oil (addition of known and identified components, derived from synthetic materials and added in correct proportions) can be very hard to find. But such “sophistications” may occasionally improve the oil and, in such a case, there is no reason for a customer to be disappointed. It should be mentioned, however, that physico-chemical properties, absolutely correct in every detail, can be established in an entirely artificial lemon oil which contains no natural oil at all. **Lemon Oils **with the labelling “USP” or “BP” or other recognized authoritative works of standards (Pharmacopoeias, Codexes, etc.) are commercially available. Certain suppliers seem to specialize in “correct physicochemical properties” of their essential oils without regard to the olfactory virtues of the oils.