350 
Good  Drinks  Made  of  Milk. 
Am.  Jour.  Pharm. 
May,  1920. 
die  and  repeat  the  process  until  one  sample  is  obtained  which  curdles 
in  at  least  8  or  lo  hours  with  a  smooth  curd  free  from  whey  and  gas 
bubbles,  and  with  a  pleasant  acid  taste. 
Gas  bubbles,  or  the  separation  from  the  curd  of  a  milky  or  straw- 
colored  whey,  show  that  the  lactic-acid  bacteria  are  still  mixed  with 
other  kinds.  Considerable  variation  in  flavor  can  be  found  in  dif- 
ferent cultures,  and  care  should  be  exercised  to  select  one  that  gives 
a  clean,  sharp  taste. 
Propagate  this  culture  in  the  same  way  from  day  to  day.  The 
amount  of  this  mother  starter  which  should  be  carried  will  depend 
upon  the  amount  of  buttermilk  to  be  made.  One  quart  should  be 
enough  for  20  to  30  gallons. 
Add  the  mother  starter  to  the  milk  to  be  used  for  buttermilk, 
or  pasteurize  the  milk  in  a  continuous  pasteurizer  at  180  to  185 
degrees  F.  (82  to  85  degrees  C),  or  preferably  hold  the  milk  in  water- 
jacketed  vats  or  cans  at  180  degrees  F.  (82  degrees  C),  for  thirty 
minutes  to  an  hour,  cool  to  about  70  degrees  F.  (21.1  degrees  C.) 
and  add  the  mother  starter.  The  most  desirable  temperature  for 
this  fermentation  is  70  to  75  degrees  F.  (21.1  to  24  degrees  C). 
When  this  milk  has  curdled,  cool  it  at  once  to  about  50  degrees 
F.  and  churn  thoroughly  to  break  the  curd  into  fine  particles. 
Buttermilk  may  be  improved  especially  as  to  its  texture  and 
tendency  to  whey  off,  by  the  addition  of  about  10  per  cent,  of  a 
milk  culture  of  Bacillus  Bulgaricus. 
Yogurt  or  Bulgarian  Buttermilk.— 'Propsigate  a  small  culture  of 
the  Bacillus  Bulgaricus  from  day  to  day  as  indicated  for  the  lactic 
culture  for  buttermilk.  This  culture  may  be  obtained  from  var- 
ious commercial  laboratories.  To  prevent  contamination  by  yeasts 
or  gas-forming  bacteria,  it  is  necessary  to  carry  this  culture  at  a 
temperature  of  about  no  degrees  F.  A  small  egg  incubator  may  be 
used  for  this  purpose. 
Carry  in  a  similar  way  a  culture  of  the  ordinary  sour-milk  or- 
ganism, which  may  be  obtained  from  many  of  the  commercial  lab- 
oratories. 
Thoroughly  pasteurize  the  milk  to  be  fermented.  If  a  small 
quantity — 5  to  10  gallons,  for  instance — ^is  to  be  made,  it  may  be 
done  by  holding  a  can  of  milk  in  a  tub  or  vat  of  water  heated  by  a 
steam  hose.  If  a  larger  quantity  is  made,  one  of  the  starter  cans 
used  in  creameries  will  be  found  convenient.  These  are  essentially 
.cylindrical  vats  with  mechanical  stirrers  and  a  jacket  which  can  be 
