214 



FIG CULTURE 



goods sterile, and should make tests about once a 

 week each season, different and more hardy spores 

 appearing from time to time which require the pe- 

 riod to be lengthened or shortened, as conditions 

 change. The higher the temperature the shorter the 

 time, and the longer fruit is sterilized the darker it 

 becomes. 



Sterilizing the final packages is done on a small 

 scale by boiling them in some such solution as salt 

 brine, calcium chloride brine, or an oil bath, they 

 having boiling points sufficiently high to raise the 

 temperature of the sealed preserves to a deadly heat. 

 One of the largest plants in the world uses oil baths 

 exclusively for this purpose. In boiling care should 

 be taken to avoid too great a difference in tempera- 

 ture between the bath and the preserves, otherwise 

 steam will generate in the packages and burst them. 

 Preserves which test 31 deg. by saccharometer boil 

 at about 214 degrees F., and it is not safe to use a 

 sterilizing bath more than two degrees higher. 

 When brine is used, the supply of salt, or calcium, 

 should be steadily maintained, as considerable quan- 

 tities adhere to the cans, or jars, in removing them, 

 reducing the density, while evaporation from ebul- 

 lition tends to its increase. 



Except on a small scale, the most satisfactory 

 method of sterilizing is in a closed chamber where 

 live steam is confined, escaping only under a regu- 

 lated pressure. In such case the heat generated on 



