574 MICROBIOLOGY OF FOODS 



the bitter principle. The lye is removed by repeated leaching of the 

 fruit with water. In former practice it was then covered with a dilute 

 brine of about 2 per cent sodium chloride which was gradually increased 

 to 5 per cent. During this "salt curing" process of two to six weeks 

 opportunity was afforded for a great variety of bacteria to develop. 

 B. coli could be found very frequently. Often gaseous fermentation 

 of the fruit developed or the surface of the olives became slimy through 

 the growth of mold, bacteria, and even amcebae or the fruit softened 

 through putrefactive organisms. Most factories now eliminate or 

 greatly shorten the brining process to avoid the bacterial changes noted 

 above. 



The olives are canned in a 3 to 5 per cent (12 to 20 salometer) 

 salt solution and sterilized at 212 to 25oF., depending upon the 

 factory. Recent investigations by the writer have shown that olives 

 heated to 2i2F. only in cans are not sterile but in practically all cases 

 contain living spore-bearing organisms. Temperatures of 230 to 

 24oF. may be used for thirty to forty minutes without seriously in- 

 juring the quality of the fruit. 



Recently several cases of botulism from commercially canned 

 olives and one from green olives have been reported. Three factories 

 were represented in these outbreaks. In all cases the olives have been 

 processed in the cans at 2i2F. only. No cases have occurred from this 

 fruit sterilized under steam pressure. Cases have been most frequent 

 from fruit canned in glass because of the difficulty of sterilizing glass 

 containers under pressure without breakage. Dr. E. C. Dickson of 

 Stanford University, Dr. K. F. Meyer of the University of California, 

 and Dr. M. J. Rosenau are engaged upon an extensive and detailed 

 study of the death temperatures and other properties of B. botulinus 

 strains from food poisoning cases. Their work is under a grant from 

 the National Canners Association, given as a direct result of the out- 

 breaks from canned olives. 



As now canned, ripe olives are safe because of effective sterilization 

 methods. 



SILAGE FERMENTATION* 



The character of the changes brought about in silage varies with the 

 material used in filling the silo and with the method of filling. Beet 

 cosettes in silos undergo alcoholic and lactic fermentation, very large 



* Prepared by W. V. Cruess. 



