4. Conclusions
The analyses of the colour indicated that the level of pigments
decreased from the surface to the endosperm and
that yellow and red pigments were concentrated in bran
and outer endosperm. Colour pigments were uniformly distributed
in the middle and core endosperm. Colour measurements
of cooked rice indicated that: (i) water uptake
during cooking, (ii) leaching of pigments in the cooking
water (excess water was used in the cooking experiment)
and (iii) diffusion of pigments from the rice surface to the
inner layers are responsible for differences in colour
between raw and cooked rices. To gain more insight into
the different rice pigments, identification of the rice pigments
present in the different rice layers is needed.
The study of the effect of milling on the nutritional properties
confirmed that the level of proteins and minerals
decreased from the surface to the endosperm of brown rice
and that the level of total starch increased from the surface
to the endosperm.