Preparation of thin discs of carrier material
Ampoules of neutral glass (45 x 10 mm) are filled with 0,1 ml of 20 % (w/v) skim milk (Bacto, Difco 0032) containing 10% (w/v) neutral activated charcoal and one of the effective protective agents such as 5 % (w/v) meso-inositol, 5% (w/v) glutamate, 5 % (w/v) raffinose or 10% (w/v) honey. The ampoules are loosely plugged with non-absorbent cotton wool and sterilized at 115 ’C for 13 minutes. These are frozen at about -30 ’C for a few hours and then freeze-dried in bulk for about 6 hours using a standard freezedrying technique