Determination of crude fibre by trichloroacetic acid
The organic residue left after sequential extraction of
sample with ether can be used to determine the crudefibre; however if a fresh sample was used, the fat in it
could be extracted by adding petroleum ether, stirred and
allowed to settle and decanted. This was done three
times. The fat-free material was then transferred into a
flask/beaker and 200 ml of pre-heated 1.25% H2SO4 was
added and the solution was gently boiled for about 30
min, maintaining constant volume of acid by the addition
of hot water. The Buckner flask funnel fitted with
Whatman filter was pre-heated by pouring hot water into
the funnel. The boiled acid sample mixture was then
filtered hot through the funnel under sufficient suction.
The residue was then washed several times with boiling
water (until the residue was neutral to litmus paper) and
transferred back into the beaker. Then 200 ml of preheated
1.25% Na2SO4 was added and boiled for another
30 min, filtered under suction and washed thoroughly with
hot water and twice with ethanol. The residue was dried
at 65°C for about 24 h and weighed; and then transferred
into a crucible and was placed in muffle furnace (400-
600°C) and ashed for 4 h. It was then allowed to cool in a
desiccator and was weighed (Oladipo and Jadesimi,
2013).
dry wt. of residue before a