Citrus aurantifolia (Christm. et Panz.) Swingle is the lime species from which distilled lime, centrifuged Key lime type A, centrifuged Key lime type B, and expressed, or cold-pressed, acid lime oils are obtained. Distilled lime (the largest volume of the lime oils produced) is prepared by squeezing clean, whole limes through the broad end of a conical screw press that is fitted with 5 mm holes. The pressure within the press forces the crushed fruit peel and pulp to be expelled from an opening at the narrow end, during which time the oil glands are burst, releasing both the oil and the juice. The oil-juice emulsion is pumped into a stainless steel still, and the mixture is subjected to a distillation time of ca. 10 hr.
An oil known as centrifuged lime oil type A is produced from the oil-juice emulsion. In this instance, the emulsion is pumped into a finisher to remove the coarse detritus. The emulsion is broken and the oil is separated from the juice by two passes through a high-speed centrifuge.
The expressed, or cold-pressed, lime oil is produced using either a rasping process or a modified whole fruit processor. In both scenarios, the released oil is washed away from the process equipment with a spray of water. The oil/water emulsion is initially screened to remove any coarse peel fragments, after which the oil is isolated from this mixture by one or two passes through a high-speed centrifuge. After cooling the oil (a process known as winterization) the waxes and a portion of the non-volatile compounds precipitate out. Cold filtration to remove the precipitate yields the oil known as centrifuged lime oil type B.