INFLUENCE OF PIGMENT COMPOSITION ON SKIN COLOR IN A WIDE-RANGE OF FRUIT AND VEGETABLES

The color of fruits and vegetables results from the presence of chloro phyll, carotenoid, and anthocyanin pigments. Instrumental measurements of color are used routinely in describing processes of changing color , such as fruit ripening. The applicability of using skin color measur ements to predict changes in pigment composition was investigated usin g a wide range of fruit and vegetables. Skin color was measured using a Hunter Colorlab and represented as the coordinates X, Y, Z, L, a*, b, chroma (C*), and hue angle (h degrees). Identical skin samples wer e extracted and analyzed for chlorophyll, carotenoid, and anthocyanin concentration. Sets of pairwise scatter plots were generated for each set of color variables and for the chlorophyll, anthocyanin, and carot enoid pigments. There were linear relationships between h degrees and anthocyanin concentration and between L and log [chlorophyll concentr ation]. Multiple regressions for each pigment variable and sets of col or variables also were calculated. However, there was no unique linear combination of pigments that gave rise to a unique point in the color space. Conversely, a given set of coordinates in the color space can be accounted for by many combinations of pigments. Therefore, a given color measurement cannot be described in terms of a unique combination of pigments. Caution is urged in interpreting tristimulus color coord inates in terms of a simple change in pigment composition without prio r knowledge of the pigment composition within the fruits and vegetable s. The surface topography of fruits and vegetables may be of considera ble significance in measuring color.