380 



MILK 



Slimy, Steingy, and Ropy Milk 



Slimy, viscous, stringy, or ropy conditions in milk are among 

 the commonest and most troublesome of all abnormal conditions 

 of milk. The consistency of milk changes so that it can be drawn 

 out into strings or threads, sometimes to a length of several feet 

 (Fig. 178). This condition is particularly obvious when the milk 

 is passed through a sieve, the threads hanging tenaciously from 

 the meshes of the sieve. The nature of such abnormal milk varies 

 considerably; sometimes the strings are fine like silk, sometimes 

 thicker; sometimes, again, the tendency is not 

 to form strings of considerable length, but the 

 milk becomes thick and of tenacious con- 

 sistency. When sliminess develops the chem- 

 ical change in the milk is slight. It may 

 turn sour in the usual fashion, and there is 

 usually no radical alteration of the casein or 

 breaking down of the milk-sugar, although 

 slime-forming organisms that break down 

 casein to the point of complete liquefaction 

 are rarely encountered. The greatest chem- 

 ical change occurs when the stringiness is due 

 to a pathologic condition of the udder. This is 

 frequently accompanied by a profound prote- 

 olysis. 



When the viscosity is caused by micro- 

 organisms the taste of the milk is not materi- 

 ally altered; the digestibility is not impaired; 

 acidity develops as usual, but the physical 

 condition somewhat veils the acid taste. In 

 some countries viscous milk is prepared for 

 the table and considered a delicacy. The 

 Norwegian tatt^ melk or tatmjolk is an ex- 

 ample. The milk is inoculated with butter- 

 wort (Pinguicula vulgaris), on which a slime- 

 forming bacterium is known to exist. In 

 conjunction with a yeast which produces an agreeable flavor a 

 fermentation begins, and a thick milk results, which is eaten with 

 a spoon or even with a knife and fork. 



Lange wei is a viscous whey that was quite generally used in 

 Holland for making Edam cheese. The whey contains a lactic 

 acid bacterium. Streptococcus hollandicus, that is the cause of 

 the viscous condition and produces acid at the same time. For 

 many years it was thought that the best quality of Edam cheese 

 could be produced only by the use of this lange wei, of which 



Fig. 178.— Slimy 

 milk. It does not 

 mix with water when 

 poured into it (Rus- 

 sell and Hastings). 



