In spite of the differences between the lightness of gluten-free and
gluten-containing ingredients there were no significant differences
in lightness of upper surfaces of all cookie formulations (Table 5).
Bottom surface of individual sample had lower L* values in comparison
to upper cookie surface, i.e. it was darker. However, gluten-free
cookies showed significantly lower (p≤0.05) redness (a*) and yellowness
(b*) values in comparison to wheat flour cookie sample for
upper as well as for bottom surfaces. Moreover, yellowness values
(b*) slightly decreased by increasing the amount of buckwheat flour
in cookie formulation. The difference in a* and b* values was presumably
correlated to the differences in amino acid profile (Edwardson,
1996) and content of reducing sugars (Table 2) between BF, RF and
WF which are responsible for intensity of Maillard reaction. Also,
the yellowness of rice and buckwheat flour was lower than the
wheat flour yellowness (Table 4)