Protein content: The crude protein was determined by
the Kjeldahl method with slight modification. 0.5 g of the
powdery form of each colored rice variety was digested
with 5 ml of concentrated sulphuric acid in the presence
of Kjeldahl catalyst. The nitrogen from the protein in the
sample was converted to ammonium sulphate that
reacted with 2.5 ml of 2.5% Brucine reagent, 5 ml of 98%
sulphuric acid to give a coloured derivative and the
absorbance read at 470 nm. The percentage nitrogen
was calculated and multiplied by 6.25 to obtain the value
of the crude protein (A.O.A.C., 1990).