572 MICROBIOLOGY OF. FOODS 



held a year or more in this way. Subsequent pickling operations con- 

 sist in leaching out the excess salt in warm or hot water, firming the 

 flesh with a dilute solution of alum and impregnation of the cucumbers 

 with plain or spiced or sweetened vinegar. 



Dill pickles are prepared by fermentation of cucumbers in a 

 40 to 45 brine (10 to 12 per cent sodium chloride) in closed barrels 

 fitted with small vent holes for escape of gas. Dill and other 

 herbs and spices are packed in the brine with the cucumbers before 

 fermentation. Enough acid is formed to preserve the pickles indefi- 

 nitely if air is excluded. Often the finished pickles are pasteurized in 

 lacquered cans for domestic use. The high acidity renders the steriliza- 

 tion very easily accomplished. 



Cauliflower, peppers, ears of sweet corn, and other vegetables have 

 been held successfully in brines of 10 to 12 per cent salt (40 to 48 

 salometer test), although the products possess a distinct " kraut " flavor. 

 If vegetables of any variety are mixed with 25 to 33 per cent of 

 their weight of salt Jthey may be preserved indefinitely without fer- 

 mentation, provided they are sealed in barrels or jars or under parafime 

 to prevent evaporation of moisture. Corn and string beans are excel- 

 lent so preserved. The process offers a home method of preserving 

 vegetables without danger from botulism. Where dry salt can not be 

 employed the vegetables may be packed in a saturated solution of salt. 

 The salt preserved products must be soaked in water before use to re- 

 move excess of sodium chloride. 



THE RELATION OF BACTERIA TO OLIVE PICKLING AND CANNING* 



The green olive of commerce is a fermented product preserved by 

 the lactic acid formed during the pickling process. The process used 

 dates from antiquity and is the result of long years of experience and 

 slow development. 



Olives of full size but still immature are used. The Queen olive 

 of commerce is principally of the Sevillano variety. The small 

 green olives are usually of the Manzanillo variety, although other 

 types are often used. 



The fruit is first placed in a lye containing about 2 per cent of 

 sodium hydroxide which is allowed to penetrate the fruit almost 

 to the pit. The lye is then removed and replaced with cold water 



* Prepared by W. V. Cruess. 



