J. Carreno et al., PROPOSAL OF AN INDEX FOR THE OBJECTIVE EVALUATION OF THE COLOR OF REDTABLE GRAPES, Food research international, 28(4), 1995, pp. 373-377
A colour index for the objective determination of the colour in red ta
ble grapes is described. This index is based on the CIELAB values. A s
tatistical study revealed a high correlation between L and b*, while
a was not a representative parameter. The usefulness of this index is
investigated to classify the red grapes depending on their external c
olour. The proposed colour index for red grapes (CIRG) is based on the
parameters L (lightness), H (hue angle) and C (chroma) and its expre
ssion is ''(180-H)/(L + C)''. All the colour indexes previously propo
sed were defined in fruits whose colour varied between yellow and red,
and, therefore, were not suitable for red grapes which show a dark vi
olet colour. This new index showed a good linearity with the visual co
lour of the berries and distinguished between sample groups of differe
nt external colour.