2.2.3. Determination of Crude Fibre
Crude fibre was determined using the method of
AOAC[10] (method14:020). About 2.0 g of the rice sample
was hydrolyzed in a beaker with petroleum ether after which
it was boiled under reflex for 30 min with 200 ml of a
solution containing 1.25% H2SO4 per 100 ml of solution. The
solution was filtered through a filter paper onto a fluted
funnel. After filtration, the samples were washed with boiled
water until they were no longer acidic. Then, the residue was
transferred onto a beaker and boiled for another 30 min with
200 ml of solution containing 1.25 % NaOH per 100 ml. The
boiled samples were washed with boiled distilled water. The
residues were filtered through Gooch filter crucible, dried at
1000C for 2 hours in an oven, cooled and washed. The
percentage crude fibre in the rice sample was calculated as
per the formula:
% Crude fiber = (Wt. after drying) / (Wt. of sample) x 100
2.2.4. Determination of Fat
Total fat in the rice sample was determined using Soxhlet
extraction for 4 hr starting with methanol and ethanol,
respectively[11]. About 250 ml clean boiling flasks were
dried in an oven at 105 – 110 0C for about 30 min and cooled
in a dessicator. Approximately, 2.0 g of samples were
weighed accurately into labeled thimbles. The dried boiling
flasks were weighed correspondingly and filled with about
300 ml of petroleum ether (boiling point 40 -60 0C). The
extraction thimbles were plugged tightly with cotton wool.
After that, the Soxhlet apparatus was assembled and allowed
to reflux for 6 hrs. The thimble was removed with care and
petroleum ether collected from the top container and drained
into another container for re-use. After that, the flask was
dried at 105 – 110 0C for 1 hour when it was almost free of
petroleum ether. After drying, it was cooled in a dessicator
and weighed. Then, % fat in the rice sample was computed
using the formula below:
% fat = Weight of fat x 100
Weight of sample