FERMENTED MILKS. 23 



tained by making buttermilk in the ordinary way and churning it 

 with an equal quantity of milk curdled with the yogurt' organism. 

 This procedure gives the desirable texture of buttermilk and a dis- 

 tinctive flavor. 



If a culture can be obtained, yogurt can be made in the home. 

 If a reasonably active dry or fluid culture can be obtained, the fol- 

 lowing procedure should be satisfactory : 



(1) Heat one-half pint of milk in a double boiler, holding it one- 

 half hour after the water begins to boil. 



(2) Cool this milk to about 100° F. (about blood heat). At this 

 temperature the container will feel warm, but not hot, to the touch. 



(3) Add a considerable quantity of the culture to this milk. If 

 it is in the form of tablets three or four should be used. 



(4) Transfer the milk to a bottle or fruit jar — or, better still, a 

 vacuum-insulated bottle — which has been rinsed with boiling water, 

 and hold overnight in a warm place. Good results may be obtained 

 by placing the bottle or jar, containing the milk, in a dish of 

 water warmed to about 100° F. The most favorable tempera- 

 ture for the fermentation is at or a little below blood heat. At a 

 little higher temperature the organism grows faster, but the curd is 

 likely to separate from the whey as a tough mass. At a lower tem- 

 perature the growth may be so slow that other bacteria gain the 

 ascendency. By the following morning the milk should be curdled 

 with a thick, somewhat stringy curd with a sharp, acid taste. 



(5) Heat 1 pint to 1 quart of milk as in (1), cool and add 1 tea- 

 spoonful of the curdled milk obtained in (4). 



Hold this milk as before, and when it has curdled break up the 

 curd by shaking vigorously in a fruit jar. 



This process may be repeated so long as the curdled milk has a 

 smooth, acid curd free from undesirable flavors and particularly 

 the yeasty flavor and odor characteristic of bread dough. The so- 

 called Bacillus bulgaricus, under favorable circumstances, will sup- 

 press other bacteria by its vigorous acid formation, but yeasts are 

 favored by the acid condition of the milk and sooner or later make 

 their appearance. Every precaution should be taken to protect the 

 milk from exposure to the air and to sterilize all utensils with boiling 

 water. When evidences of yeast contamination appear it is best to 

 start with a fresh culture. 



Yogurt may be made more palatable by adding to two parts of 

 the yogurt one part of cold water, or, better still, cold-charged 

 water, which can be bought in siphons at drug stores. Sugar and 

 lemon juice or other fruit flavor, or chocolate sirup may also be used 

 I'm (his purpose. The sugar should be added in the form of a sirup, 

 ae granulated sugar dissolves very slowly in the cold yogurt. 



