Oil of bitter almond, amygdalia amarae, is the volatile oil derived by steam distillation of the dried, ripe kernels of bitter almonds (Prunus amygdalus), peaches (Prunus persica), apricots (Prunus armenica) or other kernels containing amygdalin, e.g., cherries (Cerasus species) and plums (Prunus domestica). Prior to distillation, the fixed fatty oil is freed from the kernels by expression, then the powdered cake is macerated in water to split the glucoside amygdalin (mandelonitrile gentiobioside).
The glucoside amygdalin, which is present at a level of about 2-4% in the dried kernels, is cleaved enzymatically (enzyme emulsion), to yield benzaldehyde, hydrocyanic acid (also known as prussic acid) and d-glucose as shown in Reaction 1.
The freed poisonous hydrocyanic acid is chemically treated with ferrous sulfate and calcium hydroxide. The oil of bitter almond is then distilled, dried and immediately stored under nitrogen. This oil is termed FFPA, or Free From Prussic Acid.