Color is another important characteristic for determining visual
acceptance of RBO. The influences of domestic heating on quality of
cold-pressed RBO were studied. Color of RBO was determined by
CIE system (Table 3). The L* value is the “lightness” of a sample from
0 to 100 with 100 being pure white; the a* value describes red (þ)
to green (); the b* value represents yellow (þ) to blue (); and
zero values for “a*” and “b*” represent gray. The RBO differed in
their colors. Significant different were found between L*, a* and b*
values of RBO (P < 0.05). Roasting and steaming could reduce the
lightness of RBO and all of the heating methods could reduce the b*
value of RBO (P < 0.05). However, there are no color standards for
cold-pressed RBO and the L*, a* and b* measurement could thus be
used for color classification.