CHAPTEE XII. 



THE ANALYSIS OF MILK PRODUCTS. 



FOR the analysis of milk products, the methods described above 

 can generally be used. The following notes will show where it 

 is advisable to depart from them or to employ modifications. 



Homogenised Milk. The Adams or Ritthausen methods 

 of fat estimation should not be used. 



Sterilised Milk. The fat cannot be estimated by the 

 Eitthausen method. 



Cream. The methods given above may be employed in the 

 analysis of cream. The following method of determining total 

 solids, fat (by difference), solids not fat, and ash is convenient : 



Four to five grammes are weighed in a wide platinum basin, 

 which is placed in a water-oven, till the water apparently has 

 evaporated and the solids not fat stick to the bottom of the 

 basin ; when this occurs after about an hour's drying the 

 basin is so inclined that the fat runs down to the side away 

 from the solids not fat. Under these conditions drying is 

 completed in about five hours. It is an advantage to add an 

 equal volume of alcohol to the cream, and mix well before 

 drying, as the time of drying is thereby shortened. 



After weighing the total solids, the basin is replaced in the 

 water-oven for a few minutes to melt the fat ; 25 c.c. of amyl 

 alcohol are poured on, the basin placed again in the water-oven 

 for ten minutes, and the amyl alcohol solution of fat decanted 

 carefully while still hot ; with care, none of the solids not fat 

 passes away with the amyl alcohol. This process is repeated 

 eight times more, the basin being allowed to stand all night 

 between the fourth and fifth treatments. After the last treat- 

 ment, the amyl alcohol is drained off as far as possible, and the 

 basin and its contents dried for three hour in the water-oven. 

 The residue is weighed as solids not fat. This is now burnt 

 over a low flame, and the residue weighed as ash. Ether or 

 chloroform may be substituted for amyl alcohol, but the latter is 

 cheaper and less volatile. 



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