116 



GRADING AND TESTING MILK AND CREAM 



Very few of the creameries have, as yet, begun the regular 

 determination of the per cent of fat in their butter, most of them 

 confining their work on the composition of butter to determina- 

 tions of the per cent of moisture and the per cent of salt. The 

 three constituents of butter outside the fat, are moisture, salt 

 and curd; and where a uniform system of manufacture is adopted, 

 and the churning is done under right conditions and the butter 

 well washed, the curd content is not likely to exceed i per cent 



FIG. 31. The oil-test churn. 



or vary more than half a per cent. Consequently accurate 

 determination of the moisture and salt-contents enables a 

 creamery to estimate, very closely, the per cent of fat in the 

 butter. 



Sediment Test. Milk should be free from sediment and 

 foreign insoluble material. Producers of the raw material are 

 not always conscious of the necessity of producing clean milk, 

 and of the effects of impurities upon the finished products. 



Sediments may be seen on the bottom of a glass jar after the 



