886 EXPERIMENT STATION RECORD. 



teurization of milk, sterilization of milk, and the value of sterilized milk — its digest- 

 ibility and objections which have ])een raised against its use. A bibliography of 

 the subject is appended. 



Pasteurization of milk for butter making, H. H. Dean and F. C. Harrison 

 {Ontario Agr. Col. and Expt. Farm Bui. 117, pp. 16, dgms. 2). — Methods of pasteuri- 

 zation are briefly discussed and 6 series of experiments are reported, the results of 

 which are embodied in the following summary: 



"(1) Milk as ordinarily delivered at a creamery may be successfully pasteurized. 

 The milk used in these experiments was largely furnished by patrons who had but 

 ordinary facilities for taking care of it. In the winter we receive our milk but three 

 times a week; in summer it is delivered daily. 



"(2) On but two occasions was the acidity of the milk over 0.2 per cent. The 

 acidity averaged about 0.17 per cent. There is danger of the milk coagulating when 

 heated, if it contains more than 0.2 per cent of acidity. 



"(3) It was noticed that the lots heated at from 185 to 195° produced more foam 

 than those heated to the lower temperatures of 140 to 160°. This was most noticea- 

 ble in the samples heated to 195°. At 185° the foam was not sufficient to cause much 

 trouble in handling. 



"(4) By cooling the skim milk with water to a temperature of about 65° immedi- 

 ately after it comes from the separator we were able to return it to the patrons in 

 excellent condition for feeding, even in hot weather. 



"(5) The use of 10 to 15 per cent of culture in the pasteurized cream enabled us to 

 ripen the cream without any difficulty. The culture used was a lactic-acid bacillus. 



"(6) Pasteurization of milk at 185° and the use of a pure culture is the best 

 method of securing uniformity, keeping quality, and the mild flavor requisite for 

 export butter. 



"(7) The cooked flavor which was present in the. butter made from milk heated 

 from 185 to 195° usually disappeared at the end of about 2 weeks. In one or two 

 lots heated to 195° the cooked flavor remained for some time. There is apparently 

 no danger of cooked flavors on Ijutter made from milk pasteurized at 195° at the end 

 of 2 weeks, or by the time it would reach the P>ritish markets. 



"(8) The species of bacteria present in the milk when the animals were kept in 

 the stable were very undersirable. Many putrefactive and fecal Imcteria were pres- 

 ent, hence the necessity of keeping the stable walls and rafters well cleaned. A 

 good coat of whitewash increases the amount of light, and gives a general clean effect 

 to the stables. 



"(9) The average number of bacteria per cc. found in milk pasteurized at 140° F. 

 was 631,046, at 160° was 12,848, at 185° was 81, and at 195° was 40." 



The influence of high temperatures on tubercle bacilli in milk, C. Barthel 

 and O. Stexstrom {Centbl. Baki. n. Par., J. Aht., 30 {1901), 11, pp. 429-433).— The 

 authors briefly review the literature on this subject and report upon a number of dif- 

 ferent experiments which they have carried out. For this purpose a cow in the last 

 stages of tuberculosis of the udder was obtained and the secretion from the anterior 

 or badly affected half of the udder was mixed with the milk from the posterior quar- 

 ters of the udder, which were not as yet badly attacked by tuberculosis. It was 

 found that a temperature of 65° C. for periods of 5, 10, and 20 'minutes was not suf- 

 ficient to destroy the tubercle bacillus. Milk maintained at 70° C. for periods of 5, 

 10, and 15 minutes remained in §ach instance tuberculous. The same results were 

 obtained with experiments at a temperature of 75° C. At a temperature of 80° C. 

 the milk remained tuberculous after exposure for periods of 1, 5, and 10 minutes. 

 The milk upon which these experiments were made, on account of the advanced 

 stage of tuberculosis, had already suffered great physical and chemical changes. The 

 reaction was decidedly alkaline, and this probably accounts for the fact that tubercle 

 bacilli resisted the highest temperature for such long periods. Attention is called to 



