34 



Pasteurisation of Milk and Cream. 



i 80 deg. before setting. Heating to 170 cleg, before setting 

 produced skim milk testing 3*2 per cent, fat ; heating to 

 165 deg, 1 *8 per cent. ; 160 deg., i*6 per cent.; 150 deg., ro 

 per cent. ; and 140 deg., o*88 per cent. Similar samples of 

 milk which were set at the ordinary tsjmpsrature, without 

 heating, gave skim milk testing an average of 0*51 per 

 cent. fat. All the lots were set for 24 hours in water which 

 was at a temperature of from 40 deg. to 45 deg. Tests 

 with the creamometer showed a very indistinct " cream line " 

 in all the heated samples, especially in those heated above 

 140 deg. 



It was further found that the keeping quality of the butter 

 and of the skim milk was much improved by heating the 

 whole milk to the higher temperature before separating. 

 Three boxes of butter made in May — one from unpasteurised 

 milk, one from milk heated to 140 deg., and the other from 

 milk heated to 190 deg., were kept at an average temperature 

 of about 55 deg. until August 17th. These boxes were 

 examined from time to time, and it was noticed that the 

 butter made from milk heated to 190 deg. held its flavour 

 best, and was quite as good in other respects as the butter in 

 the other boxes. On August 17th the scores for flavour were 

 38, 35, and 32 (max. 45) in the order of decreasing tempera- 

 ture at the time of separating. The moisture-content of the- 

 pasteurised butter was 1077 per cent. — one per cent, less 

 than that of the sample of butter made from unpasteurised 

 milk. 



The conclusions drawn from the results of these experi- 

 ments are that the pasteurisation of the milk or cream 

 tends to produce uniformity of product, and adds to 

 the keeping quality of the butter. The higher the tem- 

 perature of the milk the better was the keeping quality 

 of the milk and butter, but the greater was the expense 

 of heating and cooling. Though there is probably some 

 danger of giving a "cooked flavour" to the butter, when 

 pasteurising cream at temperatures above 160 deg., no 

 such flavour was noticed in the butter made m the above 

 experiments. In connection with this question it may be 

 observed that in Denmark, where the pasteurisation of cream 



