THE MILK CONTRACTOR 255 



Washing of Cans. In some plants the cans are returned unwashed 

 to the farmer which is a very short-sighted, pernicious practice because 

 few dairy farmers have the facilities for properly cleaning them and tests 

 show that the bacterial contamination that results from the use of inster- 

 ile cans is serious. For instance, the U. S. Department of Agriculture 

 found that cans which received only the ordinary washing and rinsing 

 contained from 300,000 to 18,000,000 bacteria per cubic centimeter with 

 an average of 46,000,000. So 10 gal. of milk put in one of these cans 

 would have received an initial contamination of 100,000 bacteria per 

 cubic centimeter. Pease, from an extensive study in New York State, 

 became convinced that insterile cans were important factors in producing 

 the high bacterial counts in the milk of New York City in summer. A 

 milk plant letter of the U. S. Department of Agriculture tells of one milk 

 dealer who, on finding that the cans washed in his plant contained as 

 high as 20,000,000 bacteria, installed a more efficient washing machine 

 with the result that the bacteria were cut down to less than 200,000 per 

 can; moreover, undesirable bacterial forms that survived the old process 

 were killed. 



In small plants, cans are cleaned by hand. Where the washing is 

 properly done, they are first rinsed in cold water, then scrubbed in hot 

 water with washing powder and finally washed in clean hot water and 

 steamed with live steam if it is available. In larger establishments a jet 

 machine which successively forces sprays of cold water, hot water and 

 steam into the cans is used. This ought to be, and in many plants actu- 

 ally is, followed by a blast of dry air to dry out the cans so that neither 

 moist surfaces nor a puddle will be left in the can wherein bacteria will 

 multiply and also to keep the cans from rusting. Another style of washing 

 machine brushes out the can with hot water and washing powder after 

 which the cans are rinsed and then steamed on a jet machine. Other 

 effective types of machines are in use. The covers are washed in hot 

 water and washing powder, rinsed and dried and put in the sterile cans. 

 If the covers are not put in the cans at once the cans should be inverted 

 and kept in a clean place where they are protected from dust, flies and 

 other contaminations. Much stress is laid on this sterilization of the 

 cans and the drying them out with hot air. Where this is properly done 

 it is undoubtedly a good thing but in some plants the cans are hurried 

 through the process at such a prodigious rate that one's doubts as 

 to the efficacy of cleaning and sterilizing are raised, and in some cases 

 these suspicions are not allayed by taking the odor of the inside of the cans 

 when they arrive at the farm. It is not intended to criticize the principle 

 of cleaning and sterilizing the cans at the plant, for doing so has in a large 

 measure, corrected a flagrant sanitary dereliction, for the custom that 

 formerly obtained of returning the cans in an unwashed condition to the 

 farm was indefensible, but it is desired to point out that the work may be 



