Ill 



CHEESE 185 



sufficient to obtain a sample from the middle of the cheese, but 

 parts from just below the surface should be taken also. In 

 the case of hard cheeses and large soft cheeses a wedge-shaped 

 piece should be cut in a radial direction through the cheese so 

 as to include parts both of the interior and of the outside 

 portion. Small cheeses are best used whole for analysis. 

 If the sample has to be forwarded to the laboratory, it 

 should be either put into a tightly closing glass bottle, or if 

 this is not possible it should be wrapped in tin foil or in 

 parchment paper. 



When the sample comes to be analysed it is best in 

 the case of hard cheese to first cut away the crust and 

 then grind the remainder in an iron mortar. The ground 

 cheese ought then to be well mixed with a horn spoon 

 and a sample taken for analysis. Where a soft cheese is being 

 examined the sample (or the whole cheese in the small 

 varieties) is ground in a porcelain mortar until a completely 

 homogeneous mass is obtained. 



I. DETERMINATION OF THE PERCENTAGE OF WATER. 



Orla Jensen and Ernst Plattner 1 advise the following 

 method. In the case of hard cheeses, 3-5 g. of ground 

 cheese are dried in a vacuum over sulphuric acid for a 

 few days and then completely desiccated in the water-oven. If 

 the cheese were heated at the beginning it would melt to 

 a horny mass which would obstinately retain the last traces of 

 water. The smaller the amount of water in the 

 cheese when it is heated, the less will the paracasein turn 

 brown, and the smaller will be the loss of volatile fatty acids. 

 It is impossible, however, to avoid loss of ammonia, and if the 

 drying in the water-oven extends over a long time, all 

 the ammonia may be driven off. Clearly, then, the drying 

 of the cheese until a constant weight is obtained is im- 

 practicable, so that after the preliminary drying in vacuum it is 

 sufficient to heat for 8 hours in the water-oven and presume 

 that all the water has been got rid of. 



Soft cheese must be mixed with a considerable quantity of 

 sand before the drying begins. A small porcelain dish on which 



1 "Bertrag zur Kiiseanalyse," Landw. Jahrbuch der Schtvciz, 1906. 



