74 DAIRY BACTERIOLOGY 



Milk with Stable or Grass Taste. Formerly it was supposed that 

 a stable smell was exclusively due to air absorbed in the stable. 

 The taste, however, usually becomes worse after the milk has left 

 the stable, and it has been shown to be due to the bacteria which 

 produce the smell in the stable, i.e., the intestinal bacteria. A 

 heavy infection with manure will not only give the milk a taste of 

 manure by direct means, but will introduce a number of bacteria 

 which will continue the decomposition of the specific constituents 

 of the manure and, naturally enough, do not neglect the con- 

 stituents of the milk itself. In the same way. milk may acquire 

 an unduly strong aroma of grass in spring. In the usual course 

 some principles of colour and taste will always pass into the milk 

 from the young grass, but the strong odour of herbs, which is 

 appreciated by some people, will only arise on infection with the 

 liquid secretions of grass. 



Milk with a Taste of Turnips. As already mentioned, the milk 

 acquires this taste when the feed includes too great a proportion 

 of the pungent principles characteristic of the Cruciferae, turnips 

 and swedes being especially dangerous if given in a rotting con- 

 dition or too cold, so as to cause digestive troubles. Under these 

 conditions other roots may, of course, also have an undesirable 

 effect 1 . The taste-producing constituents of the roots need not 

 necessarily pass into the udder, but may also be introduced into 

 the milk with the manure, and, still worse, they will then be 

 accompanied by the microorganisms which vegetate on the roots, 

 and which, therefore, are equipped with those enzymes which are 

 capable of hydrolysing such substances as the glucosides of 

 mustard oil. According to Weigmann, the active organisms in 

 such cases are chiefly coli bacteria, Penicillium brevicaule and 

 certain species of oidium. C. 0. Jensen found in the course 

 of his well-known researches at Duelund dairy, which led to 

 the pasteurisation of cream for butter making 2 , that a coli 

 bacterium living in water could produce in the milk a very un- 

 pleasant turnip-like taste even when the cows had not been fed 

 on roots at all. Bacterium fluorescens liquefaciens also produces 

 a taste of turnips, and this defect is accordingly often met with in 

 milk which has been kept for any length of time at a low tem- 

 perature. Weigmann has isolated a non -liquefying fluorescing 

 bacterium, Bacterium carotce, which produces a strong smell of 

 carrots in all nutrient media. The author has cultivated this 



1 According to Johannes Uolle, " Zeitsclirift f. Untersuchung d. Nahrung 

 u. Genussmittel," 1915, Bd. XXX., p. 361, feeding with liberal amounts of 

 beets may cause betain to pass into the milk. As this substance is a base, 

 it will delay the coagulation of milk by acid. 



2 C. O. Jensen and Lunde, " Forsogslaboratoriets/' 22 Beretning, 

 1891. 



