The ash content was estimated using dry ashing method
(AOAC, 2005). Briefly, a clean silica crucible was placed into
a muffle furnace for 5 h. The crucible was cooled for 1 h in a
desiccator before being weighed until constant weight is
achieved. Finely ground sample (3–5 g) was weighed into crucible.
The sample was pre-ashed by heating the crucible on a
hot plate. The crucible was then transferred to a muffle furnace
for 6–8 h. After the ashing process is completed, the crucible
was cooled before being weighed to compute the ash content.