438 Bacteria in Relation to Country Life 



Canned meat. Canned sardines, salmon, or meat, 

 are similarly liable to be spoiled by bacteria in imper- 

 fectly sterilized goods. In the case of canned fish, the 

 organisms develop, at times, in the liquid rather than 

 on the fish itself. Various objectionable tastes and odors 

 are developed, rendering the product unfit for consump- 

 tion. Among the organisms found in spoiled meat or 

 fish, spore-forming species as well as members of the 

 coli group may be noted. 



Canned milk. In the case of canned milk, commonly 

 known as condensed milk, complete sterilization of the 

 material is not necessary. The milk is pasteurized and 

 concentrated in vacuum pans after the addition of about 

 12 per cent of cane-sugar. Condensed milk contains, 

 therefore, about 25 per cent of moisture and 50 per cent 

 of sugar, the remainder being composed of fat, protein 

 and ash. This comparatively small amount of moisture 

 and high content of sugar make conditions unfavorable 

 for the growth of those bacteria still present in the sealed 

 cans. 



The use of preservatives. Since the enactment of 

 the National Pure Food law, the canneries are no longer 

 permitted to use antiseptics or preservatives in their 

 canned goods without making a direct statement to 

 this effect. They must largely depend, therefore, on 

 heat alone for the proper conservation of their products. 

 They must exercise greater care as to cleanliness, in order 

 that fewer bacteria be present in the cans before heat- 

 ing. They must also determine carefully the safe limit 

 of heating, so that efficiency of sterilization be combined 

 with the greatest economy of time and fuel, 



