Am.  Jour.  Pharm. 
July,  iqi8. 
Stability  of  Vitamins. 
513 
fancy  are  subjected  to  heat  in  cooking;  and  at  present  the  practice 
of  food  preservation  as  a  part  of  the  conservation  movement  involves- 
the  application  of  heat.  One  need  only  recall  the  preparation  of 
canned  vegetables,  tinned  meats  and  milks,  and  the  sterilization  of 
milk  by  heating,  to  appreciate  a  further  aspect  of  the  problem. 
The  statements  as  to  the  instability  of  vitamins  toward  heat  seem, 
to  a  large  extent  at  least,  to  be  an  outcome  of  the  widely  held  belief 
that  heated  milk  is  responsible  for  infantile  scurvy,  which,  in  turn, 
is  conceived  to  be  a  deficiency  disease.  As  we  have  pointed  out  in 
the  past,  the  etiology  of  scorbutus  is  far  from  being  definitely  under- 
stood, and  the  bearing  of  the  milk  factor  in  the  genesis  of  the  symp- 
toms is  still  open  to  new  interpretations.  The  most  promising  method 
of  ascertaining  the  truth  would  seem  to  consist  in  studying  the  effect 
of  heat  on  sources  of  vitamin  that  can  be  tested  in  unmistakable 
ways.  One  of  these  is  afforded  by  the  ready  production  of  exper- 
imental avian  polyneuritis,  the  analogue  of  human  beriberi,  which  is 
easily  relieved  by  suitable  vitamin  products.  The  results  and  their 
proper  interpretation  are  usually  clear.  In  this  way  several  American 
investigators  have  shown  that  the  boiling  temperature  of  water  is  by 
no  means  entirely  destructive  to  the  antineuritic  vitamin,  even  though 
heating  under  pressure  may  be  destructive  in  its  effects. 
At  the  Lister  Institution  in  London,  Chick  and  Hume2  have  re- 
newed the  study  of  the  fate  of  vitamins  on  heating,  employing  the 
antineuritic  properties  of  the  wheat  embryo  and  of  yeast  as  test 
objects.  They  found  that  exposure  of  wheat  embryo  to  a  tem- 
perature of  about  ioo°  C.  for  two  hours  resulted  in  no  significant 
loss  in  antineuritic  "  vitamin."  If,  therefore,  it  is  included  in  the 
flour  from  which  bread  or  biscuit  is  made,  it  can  be  relied  on  to  re- 
tain its  antineuritic  properties  after  baking.  At  temperatures  in  the 
neighborhood  of  1200  C,  however,  there  was  a  swift  destruction  of 
antineuritic  properties.  This  fact  has  an  important  bearing  where 
diets  are  largely  composed  of  preserved  and  canned  foods  previously 
sterilized  at  temperature  above  ioo°  C. 
There  is  at  present  a  pronounced  difference  of  opinion  as  to  the 
nature  of  scurvy.  The  classic  experimental  animal  for  the  study  of 
this  condition  has  been  the  guinea  pig.    Hoist  has  found  that  it  will 
2  Chick,  Harriette,  and  Hume,  E.  Margaret,  "  The  Effect  of  Exposure  to 
Temperatures  at  or  above  ioo°  C  on  the  Substance  (Vitamin)  whose  Defi- 
ciency in  a  Diet  Causes  Polyneuritis  in  Birds  and  Beri-Beri  in  Man,"  Proc. 
Roy.  Soc,  B,  1917,  90,  60. 
