AROMA-DISTILLATE

The natural raw material is coarsely chopped, sliced, or cut. Peels from citrus fruits often come out of the peeling machine as long, thin strings, 100 to 200 cm long; these can be used as is. Apples can be peeled in a machine to advantage. Berries are usually cold-pressed since the juice by itself is a valuable flavor material. The press-cake from berries offers an excellent starting material for the production of aroma-distillates. The natural raw material is percolated at room temperature or at less than 50°C. The heat may be supplied by a steam jacket. The menstruum (usually pure ethyl alcohol) is circulated through the botanical material by action of a pump which returns the solvent to the top of the extractor. By means of gravity, the solvent penetrates the botanical material which is spread out on wire-trays or perforated plates stacked inside the extractor. The alcohol strength is adjusted to the nature of the raw material. Citrus peels are usually extracted with 99% or 90% alcohol, berries with weaker alcohol. The temperature and the time of extraction varies according to the construction of the automatic percolator and the nature of the raw material. The alcoholic extract is now drained from the percolator. The adherent alcohol on the plant material is distilled off under gentle heat from the steam jacket. The distillate is collected in a reservoir beneath a cooling system. Steam is then blown directly through the botanical material in the percolator, partly to recover all alcohol with dissolved aromas, partly in order to recover steam distillable aromatic principles in the raw material. The aqueous distillate in the condenser is mixed with the alcoholic percolates, and left for 24 hours to cool and separate terpenes and other poorly soluble matter. The hydro-alcoholic mixture is now distilled slowly—often in an all-glass still and over a short packed column. The distillation is continued until the entire distillate in the glass receptacle shows the desired alcohol percentage (60, 50, 45, or whatever percentage is wanted in the individual case). Citrus peel distillates are usually adjusted to 60% vol./vol., while berries, apples, hops, lupulin, and other distillates are adjusted to about 45% vol./vol. alcohol. It will be necessary, in certain cases, to redistil the aroma-distillate after a few days of maturing. Terpenes may continue to separate from citrus-distillates; other materials may cause haziness. Freshly prepared distillates often display a so-called unpleasant "still-note". This note fades away after proper ageing at 12 to 15°C in the course of one to several months. In many cases, the still-note can be eliminated by "aerating" the distillate in open containers, or by decanting the distillate repeatedly during a couple of days. Still-notes are well known among essential oils, and a perfumer or a flavorist must decide whether to accept or reject a material which displays a still-note on the basis of experience. Certain aromatic botanicals do not yield Aroma-Distillates: Angostura bark, capsicum fruit, cayenne or paprika, fenugreek seed, tonka bean, vanilla fruit, etc. will yield either a distillate of poor and uncharacteristic odor compared to the parent natural material, or they will yield no aroma at all in an experimental distillate. It is preferable to prepare Water Extracts, Alcohol-Water Extracts, Oleoresins or Tinctures from such botanical materials in order to obtain concentrated liquid aromas.