244 DAIRY TECHNOLOGY 



Yoghurt. The people inhabiting the countries border- 

 ing the eastern end of the Mediterranean prepare a milk 

 that is quite different from those previously mentioned. 

 Yoghurt is a thick curdled milk, high in acid, but contain- 

 ing little or no alcohol. It is prepared from goats', buf- 

 falos', and cows' milk. This is usually boiled, and some- 

 times the boiling is continued until the milk is evaporated 

 to one half its original volume. In the latter case the 

 product has the consistency of pudding and instead of 

 being used as a drink, is eaten, sometimes with the addi- 

 tion of dates, bread or other food. 



The different people of this region have various names 1 

 for their prepared milks, but the products are all very 

 similar. The Turks use the names "yoghurt," " yahourth " 

 and "jugurt"; the Balkan people, " kisselo melko " ; the 

 Armenians, "mazum"; the Sardinians, "gioddu"; and 

 the Egyptians, " leben " or " leben raib." 



Several investigators have studied these fermented milks 

 from a bacterial standpoint, and have isolated certain 

 organisms and applied various names to them. But the 

 opinion generally held by investigators, at the present 

 time, is that the various organisms necessary for the pro- 

 duction of milks of the yoghurt class, all may be included 

 under the name Bacillus bulgaricus. 



This Bacillus bulgaricus has a very characteristic action 

 when grown in milk. In a few hours at the optimum 

 temperature (about 100 F.) a curd is formed that is rather 

 soft, sometimes shiny, and does not settle to the bottom or 

 " whey off " upon long standing. The acidity of the milk 

 may reach two per cent in twenty hours and three per cent 

 after several days. 



1 U. S. Dept. of Agr., Bu. An. Ind., An. Kept., 1909. 



