Am.  Jour.  Pharm. 
Jan.,  1888. 
Antiseptic  Action  of  Hops. 
25 
THE  ANTISEPTIC  ACTION  OF  HOPS.^ 
By  Dr.  Hayduck. 
In  a  previous  communication  the  author  had  stated,  as  the  result 
of  experiment,  that  hops  do  not  influence  detrimentally  the  alcoholic 
fermentation,  but  that  on  the  other4iaQd  they  retard  the  lactic  acid 
fermentation.  In  a  further  investigation  the  author  has  sought  to 
ascertain  to  which  of  the  hop  constituents  this  antiseptic  action  is  due. 
Oil  of  hops,  as  well  as  the  hop  tannin,  proved  inactive  in  suppress- 
intr  the  lactic  acid  fermentation.  Better  results  were  obtained  with  the 
bilter  acid,  as  well  as  with  certain  resinous  constituents  which  were 
separated  by  the  following  process  : — 
The  hops  were  perfectly  extracted  with  ether,  and  the  extract,  after 
removal  of  the  ether,  was  dissolved  in  alcohol;  this  left  a  residue  of  a 
white  wax  which  occurs  in  hops  in  considerable  quantity,  but  which 
is  of  no  importance  in  brewing.  The  alcohol  solution  was  then  treated 
with  an  alcohoHc  solution  of  acetate  of  lead,  which  threw  down  an 
abundant  yellow  precipitate.  This  was  separated  by  filtration,  care- 
fully washed,  and  decomposed  with  sulphuretted  hydrogen,  yielding 
eventually  a  soft  resin.  The  filtrate,  after  removal  of  the  alcohol,  was 
treated  with  light  petroleum  spirit,  which  took  up  a  second  soft  resin 
thit  was  left  on  evaporation  of  the  petroleum.  In  the  residue  there 
was  left  a  hard  resin,  which  was  insoluble  in  light  petroleum  spirit, 
but  readily  soluble  in  ether  and  alcohol. 
In  this  way  therefore  three  well  characterized  resins  were  separated 
from  the  hops  : — 
(1)  A  soft  resin,  precipitated  by  lead.  If  an  ethereal  solution  of 
this  resin  be  treated  with  solution  of  copper  sulphate  the  ether  is 
colored  an  intense  green ;  the  resin  therefore  appears  to  form  with 
copper  sulphate  a  green  compound  soluble  in  ether.  This  resin  is  also 
soluble  in  light  petroleum  spirit. 
(2)  A  soft  resin  that  corresponds  with  the  preceding  in  being  solu- 
ble in  light  petroleum  spirit  a  id  in  giving  the  copper  reaction,  but 
differs  from  it  in  not  being  precipitated  by  lead. 
(3)  A  hard  resin  which  is  not  precipitated  by  lead,  does  not  give 
the  copper  reaction,  and  is  insoluble  in  light  petroleum  spirit. 
The  bitter  acid  is  not  obtained  by  this  process. 
^  From  the  PharrnaceiUische  Centralhalle,  Oct,  ;  reprinted  from  Phar.  Jour, 
and  Ti  ans.,  December  17,  L887,  p.  500. 
