VANILLA 137 



change in the constituents is probably due to the action of enzymes 

 of which two, a hydrolysing enzyme and an oxydase have been 

 detected, but the exact nature of the change or of the substances 

 acted upon is not known. The cured fruits, which are of a dark 

 brown or nearly black colour, are bound in bundles and packed in 

 tins, in which they gradually become coated with minute crystals. 



Description. Commercial vanilla occurs in slender flexible stick- 

 like pods about 15 to 20 cm. in length, and of a dark brown or nearly 

 black colour. They have a flattened-cylindrical shape, due to the 

 mutual pressure of the pods in the bundle, and taper towards both 



FIG. 78. Vanilla. Transverse section of fruit, showing the 

 placentas, seeds, and secreting hairs on inner epidermis 

 of the pericarp. Magnified. (Moeller.) 



base and apex. The surface is longitudinally wrinkled and frequently 

 more or less covered with numerous minute glistening crystals (of 

 vanillin). The fruits are one-celled and contain innumerable, minute, 

 black seeds embedded in a dark-coloured, aromatic, balsamic fluid 

 secreted by the cells of the inner epidermis of the pericarp, which are 

 developed into short hair-like processes projecting into the cavity 

 of the fruit. The drug has an extremely fragrant odour and an 

 agreeable aromatic taste. 



Constituents. The principal aromatic constituent of vanilla pods 

 is vanillin, though probably other aromatic substances are present ; 

 it is contained in the fluid secreted by the inner epidermis of the 

 pericarp, which gradually permeates the whole fruit, and constitutes 

 the crystalline deposit that slowly accumulates on the pods. 



