516 SOUTHERN FIELD CROPS 



(1) Cane not thoroughly ripe in the upper joints, that is, cane 

 topped rather high, since it is these partially ripened internodes 

 that contain the largest proportion of noncrystallizable sugar. 



(2) Juice that is slightly acid, as indicated by its changing 

 blue litmus paper to a reddish color. If the perfectly fresh 

 juice is not distinctly acid, it becomes acid after standing for a 

 time, and after being repeatedly strained, by which it is brought 

 into contact with acid-forming germs. 



(3) Slow cooking is desirable, since crystallizable sugar may be 

 changed to glucose when heated for a long time in the presence 

 of an acid, as in the acid juice. 



(4) Stopping the cooking before the sirup becomes very con- 

 centrated checks the tendency to crystallize. 



(5) Exclusion of air, by canning or bottling while hot, is an 

 effective means by which sirup is kept from turning to sugar. 



501. Effects of canning. The sirup that commands 

 the highest price is that which, while still boiling hot, is 

 placed in cans, jugs, bottles, or other air-tight vessels, 

 and promptly sealed, using solder on tins or sealing wax 

 on top of the cprks of jugs or bottles. 



The reason for placing sirup while hot in air-tight 

 vessels is to prevent the entrance of germs, which would 

 cause the sirup to ferment. Intense heat destroys what- 

 ever germs may be already present in the empty vessels. 

 However, it is best first to sterilize these vessels, that is, 

 to kill the germs in them, by the use of steam. It has been 

 found possible to preserve sirup in an unfermented con- 

 dition in tight barrels which had been sterilized by steam 

 and sealed while the sirup was still very hot. However, 

 it is usually not possible to keep barreled sirup in a com- 

 pletely sterile condition. Hence, barreled sirup should 

 be consumed in winter, while that preserved in sealed cans, 

 jugs, or bottles may be safely kept for use in warm weather, 



