2.2.2. Determination of Ash Content
Total ash of the rice sample was determined by Furnace Incineration described by AOAC[10] (method 14:006) based
on the vaporization of water and volatiles with burning
organic substances in the presence of oxygen in the air to
CO2 at a temperature of 600 0
C (dry ashing). About 1.0 g of
finely ground dried sample was weighed into a 277 tared
porcelain crucible and incinerated at 600 0
C for 6 hr in an
ashing muffle furnace (Model 1184A Fisher Scientific,
Houston, TX) until ash was obtained. The ash was cooled in
a dessicator and reweighed. The % ash content in the rice
sample was calculated as:
% Ash = Weight of Ash x 100
Weight of original sample
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
1000
C 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