The CDTA-insoluble pellet was the extracted with 20 ml of 50 mM Na
2CO
overnight at room
temperature
and then constantly stirred for 3 h. The homogenate
was
centrifuged, the supernatant was filtered, and the pellet was
washed
with 10 ml of distilled water. The filtrate and washings
were
pooled and designated the Na
2
CO
3
3
-soluble fraction (NSF),
which
is considered to be covalently bound pectin. The remaining
pellet
was extracted with 20 ml of 4 M KOH for 3 h at room temperature
with shaking. The mixture was centrifuged, the supernatant
was
filtered, and the pellet was washed with 10 ml of distilled
water.
The filtrate and washings were combined and designated
the
KOH-soluble fraction (KSF), which is considered to be mainly
hemicellulose.
The
residue
is considered to be mainly cellulose.