MUSTARD 



lower part being slightly thickened and polygonal in surface view; 

 two or more inner layers of thin- walled colorless cells; a single layer 

 of cells containing aleurone grains and fixed oil, and some obliterated 

 cells, which, together constitute the endosperm. The embryo makes 

 up the greater portion of the seed, and the cells contain aleurone 

 grains and an oily cytoplasm. 



FIG. 127. White mustard. Surface view of the different tissues as seen in the 

 powder : ep, polygonal cells of the outer epidermis showing mucilage lamellae 

 and the reduced lumina due to swelling of the lamellae; se, collenchymatous 

 cells beneath the epidermis; b, elongated stone cells (so-called beaker cells); 

 i, parenchyma cells beneath the stone cells, which are distinguished from the 

 corresponding layer in a number of other seeds by not containing any pig- 

 ment; P, cells of endosperm containing aleurone; C, tissue of cotyledon 

 containing aleurone grains and oil. After Moeller. 



Constituents. Fixed oil 20 to 25 per cent; mucilage in the outer 

 wall of the epidermal cells; proteids about 30 per cent; a glucoside 

 sinalbin and a ferment myrosin, which yield on interaction a yellow- 

 ish non-volatile oil (acrinyl sulphocyanide) which is pungent to the 

 taste, but owing to its non-volatile character, does not affect the eyes 

 or nose. In the reaction there is also formed glucose and acid sin- 

 apine sulphate. Sinapine is an alkaloid which is decomposed, on 

 heating its solutions with alkalies, into choline and sinapic acid. 



White mustard should contain not more than 24 per cent of 

 oil; not less than 35 per cent of protein substances, and not more 

 than 12 per cent of crude fiber. 



Standard of Purity. Mustard seed is the seed of Sinapis alba L. 

 (white mustard), Brassica nigra (L.) Koch (black mustard), Brassica 

 juncea Hook f. et Th., or varieties or closely related species of the 

 types of Brassica nigra and Brassica juncea. 



Sinapis alba (white mustard) contains no appreciable amount of 

 volatile oil. It contains not more than 5 per cent of total ash, nor 

 more than 1.5 per cent of ash insoluble in hydrochloric acid. 



