MICROBIOLOGY OF FERMENTED FOODS 573 



which is frequently changed until the fruit is practically free from lye. 

 The lye hydrolyzes the amygdalin, a bitter principle of the olive. 



The olives are then placed in barrels and the barrels filled with a 

 brine of 7 to 10 per cent. (28 to 40 salometer) salt solution and rolled 

 into a warm room or the warm sunshine to undergo spontaneous fer- 

 mentation. Many types of organisms develop but the high salt con- 

 centration favors the growth of lactic bacteria. Six weeks to two 

 months is necessary for the fermentation. Air must be excluded 

 to prevent the growth of acid-destroying organisms and to prevent 

 browning of the color of the olives by oxidation. The finished olives 

 are packed in glass containers without sterilization. The acidity 

 of the fruit is relied upon to preserve the product. The characteristic 

 flavor of green olives is due to fermentation. Often, however, various 

 decompositions occur in the jar resulting in softening of the fruit and the 

 development of a disagreeable flavor and odor. B. coli is a common 

 offender in this regard. The writer believes that a much more health- 

 ful and sanitary product would be obtained if the bottled olives were 

 pasteurized. 



Ripe olives are packed extensively in California in cans. The 

 finished product is dark brown or black in color and neutral or 

 slightly alkaline in reaction. The usual process consists, first, in plac- 

 ing the ripe fruit in barrels or tanks filled with 5 to 7 per cent, brine. 

 In these containers, a vigorous gaseous and lactic acid fermentation 

 takes place for about two weeks and a film of yeast-like cells accumu- 

 lates at the surface in many cases. Some factories omit this prelimin- 

 ary fermentation but those who employ it claim that it renders the olives 

 firmer, porous, easily penetrated by the lye used in pickling, and of 

 superior flavor. The writer's experience leads him to believe that the 

 fermentation process has little merit and may be one source of infection 

 of olives with B. botulinus. 



The olives are treated, in the usual process, with dilute lye % 

 to 2 per cent sodium hydroxide for a period of time sufficient 

 to permit the lye to penetrate the skin of the fruit and a short distance 

 into the flesh. They are then exposed to the air or are submitted to a 

 stream of compressed air in water to darken the color. The polyphenols 

 of the olive flesh rapidly oxidize to a black color in the presence of air 

 and dilute sodium hydroxide. The darkened fruit is given a second 

 lye weaker than the first until the lye reaches the pit. This destroys 



