in CHEESE 



'95 



noticed, and when a point is reached at which the milk becomes 

 thick and cheesey (which always happens suddenly), the exact 

 time in seconds is noted. During the whole of the time of the 

 experiment the milk must have a constant temperature of 

 35 C. 



The solutions of rennet which are to be used for such tests 

 must have the following strengths : (a) In the case of rennet 

 liquids, 10 c.c. are diluted to 200 c.c. with water, (h) Rennet 

 powders, T25 g. are dissolved in 200 c.c. water. 



The strength is obtained by aid of the following formulae : 



With liquid rennet, 



With rennet powder, 



W = 



w== 640-000 



If the milk used for such determination is quite pure, normal 

 and fresh, the strengths of the standard rennet and of the 

 rennet being tested are directly comparable and proportional. 

 Where the milk is not absolutely in accordance with the above 

 requirements, and this must be regarded as the usual condition, 

 it must be sterilised for from half to three-quarters of an hour at 

 75-80 C. in order to permit of the two solutions of rennet being- 

 compared with one another. If then the strength of the 

 standard rennet and of the rennet which is being tested have 

 been ascertained in the manner described above, the real 

 strength of the latter may be calculated in the following 

 manner : 



With rennet solutions, 



With rennet powders, 



, = W 



, = W* 



where 



W = strength of standard rennet with normal milk. 

 W l = rennet being treated with normal milk. 

 t = time of coagulation of abnormal milk with standard 



rennet. 

 t l = ditto with the rennet being tested. 



o 2 



