MICROFLORA OF BUTTER 125 



The original defects in taste 'are due to original milk defects 

 (and therefore also possibly to the feed), to milk defects arising 

 at a later stage, i.e., secondary defects, faulty ripening and impure 

 salt. What has been said under the heading of milk regarding 

 stable, grass, turnipy and bitter tastes, applies also to butter. 

 When butter has a strong taste of grass it often contains numerous 

 small gas bubbles, which show the defect to be due to gas-producing 

 organisms, i.e., intestinal bacteria. Yeasts which ferment lactose 

 may produce gas bubbles and give to the butter a peculiar yeast- 

 like taste. Defects of this nature are generally to be avoided by 

 pasteurising the cream.. On the other hand, pasteurisation will 

 not prevent a metallic taste (which may arise in butter through 

 washing with ferruginous water), and secondary defects due to 

 faulty souring. A cooked taste is not so often due to heating the 

 cream to too high a temperature as to heating it for too long, as 

 may occur if the cooling after pasteurisation is too slow ; the 

 taste often arises through the milk having too high an acidity, 

 which causes the proteins to separate and burn on the pasteuriser. 

 A burnt taste may also arise in this way ; as already mentioned, a 

 burnt, oily or tallowy taste may also be due to faulty souring, while 

 the effect of sunlight or copper salts in producing tallowiness has 

 also been alluded to. If the salt used contains appreciable amounts 

 of magnesium salts, it may give a bitter taste. 



Although for the sake of uniformity distinction has been made 

 between original and secondary defects, it must be admitted that 

 the line of demarcation between the two is by no means sharp. 

 Thus a defect such as unclean taste, which is produced by various 

 putrefactive bacteria (proteus, coli bacteria, etc.), may develop 

 sooner or later in the history of. the butter. The term original 

 defects will be applied to such defects as come out immediately or 

 during the first few days after the butter has been made, and then 

 disappear either partially or completely ; by secondary defects 

 will be understood those which develop gradually and become 

 worse as time goes on. 



Secondary defects are of course counteracted by any condi- 

 tions tending to increase the keeping powers of the butter, i.e., good 

 raw material, efficient pasteurising, pure starter, proper churning, 

 thorough washing with good water, proper working and salting, 

 clean air, sterile and airtight packing, and the most thorough 

 cooling possible. Defects in appearance include mouldy spots 

 which are generally accompanied by a mouldy smell ; it must be 

 mentioned that many kinds of moulds may grow on butter besides 

 those which generally cause rancidity, and although most of these 

 organisms may be able to hydrolyse fat, moulds are known which 

 do not do so. Oidium lactis cannot as a rule be seen in butter 



