94 FRUITS 



aroma of the peel is due ; at the same time too much of the white 

 ' zest ' should not be removed, as that is lacking in bitterness. It 

 may readily be dried in a warm room but large quantities of the dried 

 peel are imported, especially from Malta ; in the latter case it is 

 generally in the form of very narrow strips cut by machinery (' gelatin 

 cut '), or in wider spiral strips or in four ' quarters.' English cut peel 

 is generally rather thick, but has a fine colour and aroma. The 

 transverse section assumes a dark green colour when moistened with 

 strong hydrochloric acid, a reaction that is occasionally useful in 

 identifying the peel. 



Constituents. Bitter orange peel contains volatile oil, aurantiamarin 

 (an amorphous bitter principle), hesperidin, isohesperidin, hesperic 

 acid (colourless, tasteless crystals), a bitter resin and bitter auranti- 

 amaric acid The peel yields from 3*5 to 6'5 per cent, of ash. 



The seeds contain about 40 per cent, of fixed oil, pectin and a 

 crystalline bitter principle, limonin. 



Hesperidin, C 2 2H 26 O 12 , is a colourless, tasteless, crystalline glucoside that 

 occurs in all species of Citrus and in many other Rutaceous plants ; by hydro- 

 lysis it yields hesperetin together with dextrose and rhamnose ; hesperetin 

 may be split up into isoferulic acid and phloroglucin. 



Substitutes. The peel of the sweet orange is said to be frequently 

 mixed with that of the bitter orange ; it may be distinguished by 

 being thinner, paler, and more yellow in colour and much less bitter 

 in taste. Lemon peel (dried) scarcely changes colour with strong 

 hydrochloric acid. 



Uses. Bitter orange peel possesses both aromatic and bitter 

 properties, and is used as a tonic and as an agreeable flavouring agent. 



Oil of Neroli is the volatile oil distilled from fresh orange flowers ; chief con- 

 stituents linalol, geraniol (and their esters), limonene and methyl anthranilate 

 (ortho-amidobenzoate). 



Orange Flower Water is a saturated aqueous solution of the volatile oil obtained 

 during the distillation ; the residue contains the bitter principle limonin (naringin). 



Oil of Orange is the volatile oil obtained from the rind of the bitter orange ; 

 chief constituents eZ-limonene, citral, citronellal, decyl alcohol, methyl an- 

 thranilate. 



Oil of Portugal, the volatile oil from the rind of the sweet orange, has similar 

 constituents. 



Oil of Petit Grain, the volatile oil obtained originally from the immature fruits 

 but now frqm the leaves and twigs, has also a very similar composition. 



LEMON 



(Fructus Limonis) 



Source, &C. The lemon is the fruit of Citrus Medica, Linne, var. 

 p-Limonum, Hooker filius (N.O. Rutacece), a small tree which, like the 



