2.2. Steam explosion pretreatment
Proper DI water was added to 150 g dried fig leaves for rehydration
with the liquid–solid ratio (L/S, mL/g-dry) value of 3 for 1 h
before the leaves were under steam explosion pretreatment in a
2-L vessel. The vessel was designed by our own laboratory which
consisted of a reaction chamber, a reception chamber and a steam
generator (Weihai Automatic Control Co., Ltd., China). Two groups
of fig leaves were marked according to the pretreatment conditions.
For one group, in order to keep the initial shape of fig leaves,
0.2 MPa saturated steam was inlet into the vessel and the pressure
was sustained for 3 min before the decompression valve was
opened instantaneously. Comparatively, 0.4 MPa saturated steam
was passed into the vessel and the pressure was sustained for 3 min
for the other group. The steam exploded fig leaves were air-dried
and stored in a 4 ◦C refrigerator until usage.