Tonka Beans

#### Tonka "Bean". **Tonka "Beans" **are the seeds from the fruits of a large tree, **Dipteryx Odorata **(and other species of **Dipteryx**) which grows in western and northeastern South America, particularly in Venezuela, the Guianas and Brazil. The tree also grows in Nigeria, West Africa, but production of beans for export has been irregular and remains unimportant in Nigeria. The seed is removed from the ripe fruit and is dried and soaked in alcohol or rum for 12 to 24 hours. The seeds then swell and, when they are removed from the alcohol bath, they shrink on drying, and on the surface appears the well- known crystalline frosting of coumarin. This treatment is partly a curing, partly a conventional "sales promotion" process. The customers expect this particular appearance of tonka beans although the "frosting" is no criterion of high quality. Rum is used mainly because it is the cheapest form of local alcohol. Tonka Beans are shipped via the seaports of Maracaibo, Port of Spain (Trinidad is a transit station, not a producing area) and Belem (the Brazilian **Para**-tonka beans). After curing in the country of origin, the beans are not processed further, but are shipped to Europe and the U.S.A. **Tonka Beans **do not yield any appreciable amount of aromatic oil upon steam distillation, but they are extracted with various solvents to produce tinctures, concrètes and absolutes (see the monographs on Tonka Absolute and Tonka Concrète). Under the first heading, the tincture is described; under the latter the so-called resin or resinoid of tonka, which is a concrète according to the terms of this work, is described. In order to evaluate tonka beans, it is necessary to perform a test extraction. Even if he has solid knowledge and good experience in the trade of tonka beans, it is not possible for the perfumer to judge the quality directly. Adulteration is practically out of the question when the consumer buys the whole beans. However, "artificial" frosting with a solution of synthetic coumarin is not an unknown sophistication. Due to the coumarin ban since *1953** *in the U.S.A., tonka beans are no longer used in flavors for food or candy, beverages, etc., but they still find use in tobacco flavoring in a number of countries. The masking effect of tonka bean fragrance is well known. Cod liver oil, iodoform and other strong smelling pharmaceutical products were once perfumed with these odorous seeds. The use of tonka beans as an insecticide (against moths in clothes cabinets, etc.) is practically obsolete. Since the tonka "bean" does not contain any significant amounts of resinous matter, the author prefers to use the term "**Concrète**" for the hydrocarbon- or acetone-extracted products of the bean. Benzene, acetone, ethyl ether or petroleum ether are used in the extraction of the coarsely pulverized, dried tonka "beans". Hot extraction is not advantageous since it draws out waxes and fats which are solid at room temperature and must be eliminated anyway. Percolation gives good results. The extract is evaporated under gentle vacuum until all solvent is removed. The resulting residue is **Tonka Concrète**, and its appearance varies according to the solvent used. A considerable amount of fixed (vegetable, fatty) oil is present, and the concrète is rarely a homogeneous mass. Its color is amber to brownish yellow, and it will form a white or creamy-colored deposit of crystallized coumarin, which is present in such amounts that it is not soluble in the oil. When acetone is used in the extraction, the moisture which is enevitably present in the "beans" will go into the acetone and impair its solvent action. It will also result in the fatty oil separating from the acetone-extract before or during the evaporation. This can be of some advantage to a quicker elimination of the fixed oil. But this fatty oil has a considerable amount of coumarin and other aromatic substances in solution, and must be thoroughly washed (with ethyl alcohol) before it can be disposed of as useless. Some producers even take advantage of this aromatic fixed oil by producing a "tonka oil" which is used as an oil-soluble tonka flavor of suave sweetness and excellent tenacity and stability e.g. in baked goods. This oil can turn rancid on prolonged storage unless it is properly treated with an antioxidant (permitted in food products). Petroleum ether extraction leads to a pale amber colored and very attractive concrète of a true-to-nature aroma, and free from water. The yield is slightly smaller than by benzene extraction which gives a somewhat darker concrète. **Tonka Concrètes **are used in tobacco flavoring in countries where a coumarin ban does not exist. For perfumery, the **Absolute**** **(see this monograph) is preferred for better solubility and absence of fixed oil. **Tonka Resin **is a conventional term for a solid extract of tonka "beans", usually by means of benzene. The fatty oil may be eliminated, but the so-called resin still contains natural waxes. It is not infrequently adulterated with synthetic coumarin. It does not contain natural resins from tonka in any significant amount. Methyl abietate, deodorized dihydro methyl abietate, hydroabietic alcohols, Sumatra benzoin extracts, etc. may be added to tonka bean extracts to give them an appearance of "resins". Similar compounded products are offered under the name of **Tonka Resinoid**.