HEAT IN THE PRESERVATION OF FOOD PRODUCTS 529 



examined 530 cans of salmon representing 9 brands, and found 237 

 unsterile cans; 224 of these contained the same organism of the B. 

 mesentericus group, either in pure culture or in connection with other 

 species. Tinned sardines show a high percentage of organisms of the 

 colon group. As the intestines are not removed before the fish are 

 packed, this would naturally be expected. Weinzirl concluded that 

 food poisoning organisms such as B. botulinus and B. enteritidis, etc., 

 are not found in commercial canned foods. Burke, however, in 1919, 

 examined 235 cultures from a wide range of material in California, 

 including tap water, hay, leaves, vegetables, fruits in various conditions, 

 insects, spiders, sowbugs, snails and caterpillars, garden soil, manure 

 from horses, hogs and chickens, and also samples from the claws and 

 beaks and from the crop, gizzard and intestinal contents of birds. 

 Seven cultures containing B. botulinus were found. Burke concluded 

 from her research that "B. botulinus is widely distributed in nature; 

 that it is present in the garden and may be on the fruits or vegetables 

 when they are gathered." Bigelow and Estey, in a paper read before 

 the Society of American Bacteriologists in December, 1919, emphasize 

 the importance of further knowledge of the thermophilic organisms. 

 " These bacteria are frequently mentioned but practically nothing has 

 been done with them. We have quite a number of them isolated, some 

 of them being acid formers and producing "flat sours," and others 

 being gas forming. One of them converts starch to maltose and pro- 

 duces the so-called "sweet hominy." Another one turns milk bitter 

 and has caused some spoilage in evaporated milk which was not 

 recognized as bacterial spoilage. Some of these organisms do not appear 

 to grow below the temperature of 42C., and grow as high as 76C. 

 Others grow readily at 65C. and as low as room temperature. We do 

 not know how much higher or lower. These resistant spores do not 

 appear to grow at a lower pH value than about 4.7. They therefore 

 are not expected to give any difficulty in processing products as acid as 

 tomatoes or as the ordinary fruits. The lesson from the data secured 

 is that foods should be processed at as high a temperature as possible. 

 These resistant organisms require many hours for the destruction of 

 their spores. The spores are not destroyed by fractional sterilization. 

 If these spores are present and a high temperature is not used for their 

 destruction, they will cause spoilage." 



