40 MASS. EXPERIMENT STATION BULLETIN 374 



iodine required to effectively control the bacterial content of even a milk 

 of low bacteria content would be sufficient to spoil the taste for most 

 consumers. In addition, it would probably be unwise for one to consume 

 that much iodine day after day except under the direction of a physician 

 who might prescribe it for some specific purpose. 



Glickstein approached the subject from a somewhat different angle. He 

 compared the effectiveness of pasteurization and iodine treatment (?0, 

 100, 150, and 200 parts per million, presumably within the limit of the 

 probable physiological tolerance of consumers) for the control of bac- 

 terial growth in several grades of milk. Plates were made from both 

 pasteurized and iodized milk at 12, 24, 48, and 72 hours. Pasteurization 

 was found to be several times as effective as even 200 p. p.m. of iodine. 

 In addition, the iodine seemed to lose its effectiveness as keeping-time 

 increased, while the effect of pasteurization was lasting. The percentage 

 increases of bacteria in iodine-treated milk with high initial bacteria con- 

 tent appeared to be less than in milk with low initial bacteria content. The 

 results of the experiments do not encourage the use of iodine for the con- 

 trol of bacterial growth. 



In milk of exceptional quality (plate counts below 1000 per milliliter) 

 a little iodine added to the milk may be all that is needed to hold bacteria 

 in check. However, proper care of the milk, especially prompt and ade- 

 quate refrigeration, would protect the quality of the milk without resort 

 to other procedures. If it is desired to add iodine to such milk for med- 

 icinal purposes, that is another story and is not pertinent here. 



Publication of this Document Approved by Commission on Administration and Finance 

 3m-8-40 — 3625 



