1 76 CULTURE MEDIA 



3. Place the flask in a water-bath regulated to 60 C. 

 and allow the maceration to continue for one hour. 



4. Strain through butter muslin into a clean flask 

 and heat in the steamer for thirty minutes. 



5. Filter through Swedish filter paper. 



6. Tube in quantities of 10 c.c. or store in flasks. 



7. Sterilise in the steamer at 100 C. for twenty 

 minutes on each of three consecutive days. 



The natural reaction of the wort should not be inter- 

 fered with. 



NOTE. It is sometimes more convenient to obtain " unhopped" 1 

 beer wort direct from the brewery. In this case it is diluted 

 with an equal quantity of distilled water, steamed for an hour, 

 filtered, filled into sterile flasks or tubes, and sterilised by the 

 discontinuous method. 



Wort Gelatine. 



1. Measure out wort (prepared as above), 900 c.c., 

 into a sterile flask. 



2. Weigh out gelatine, 100 grammes ( = 10 per cent.), 

 and add it to the wort in the flask. 



3. Bubble live steam through the mixture for ten 

 minutes, to dissolve the gelatine. 



4. Cool to 60 C. ; clarify with egg as for nutrient 

 gelatine (vide page 164). 



5. Filter through papier Chardin. 



6. Tube, and sterilise as for nutrient gelatine. 



Wort Agar. 



1. Measure out wort (as above), 700 c.c., into a 

 sterile flask. 



2. Weigh out powdered agar, 20 grammes; mix into 

 a smooth paste with 200 c.c. of cold wort and add to 

 the wort in the flask. 



3 . Bubble live steam through the mixture for twenty 

 minutes, to dissolve the agar. 



1 "Hopped" wort exerts a toxic effect upon many bacteria, including the 

 lactic acid bacteria. 



