ENZYMES AND OTHER FERMENTS DIGESTION. I2/ 



out action on malt sugar or milk sugar and which, at the same 

 time, will not induce alcoholic fermentation. This property 

 of the yeast extract is made use of in the determination of cane 

 sugar in presence of the others just mentioned. 



GLUCOSIDE REACTIONS. 



For our purpose it will not be necessary to go into many 

 details here. A few decompositions only need be mentioned 

 by way of illustration. The glucosides are peculiar com- 

 pounds which may be looked upon as more or less complex 

 ethers of glucose. They are decomposed in various cleavage 

 processes, with the separation, usually, of glucose as one of the 

 constituent products. 



Emulsin. The best known reaction in this group is that 

 which takes place spontaneously in the crushed bitter almond. 

 Along with other substances this kernel contains a character- 

 istic nitrogenous glucoside known as amygdalin and the en- 

 zyme called emulsin. In presence of water the amygdalin 

 breaks up in this way: 



CaoH^NOu + 2H 2 = 2C 6 H 12 6 + HCN + C 6 H 5 CHO, 



that is, glucose, hydrocyanic acid and benzoic aldehyde are 

 formed. In the uncrushed dry almond this reaction does not 

 take place because the enzyme and glucoside are not in direct 

 contact, but are contained in different cells. The same result 

 is accomplished by distillation of the bitter almond with dilute 

 acids. 



Similar reactions are observed with salicin, 



C 13 H 18 O 7 + H 2 O = C 6 H 12 O 6 + C 6 H4.OH.CH 2 OH, 



Saliginin 



and with coniferin, arbutin and other glucosides. A related 

 ferment, known as myrosin, converts the potassium myronate 

 found in black mustard into allyl mustard oil, C 3 H 5 NCS, 

 glucose, and potassium acid sulphate. 



