Colorimetric Study. Instrumental measurements of color were
conducted at room temperature with a Minolta Chromameter (Chroma
Meter CR-200; Minolta Camera Co. Ltd., Osaka, Japan) by placing the
tomato powder in a 15 mm thick and transparent plastic cell without
cover and by using a black plate as the background to standardize the
measurements.20 The chromameter consisted of an 8 mm diameter
measuring area, and diffuse illumination/viewing was utilized. The
tristimulus values of CIE L*, a*, b* readings were calibrated against a
standard white plate. CIE 1976 uniform color space was taken into
account for the colorimetric analysis. Within the CIELAB uniform space,
a psychometric index of lightness, L* (ranging from 0, black, to 100,
white), and two color coordinates, a* (which takes positive values for the
direction of redness and negative values for the direction of the
complement green) and b* (positive for yellowness and negative for
blueness), are defined.21 The data of each measurement are the average
of triplicate measures on equidistant points of the sample.
Colorimetric Study. Instrumental measurements of color were
conducted at room temperature with a Minolta Chromameter (Chroma
Meter CR-200; Minolta Camera Co. Ltd., Osaka, Japan) by placing the
tomato powder in a 15 mm thick and transparent plastic cell without
cover and by using a black plate as the background to standardize the
measurements.20 The chromameter consisted of an 8 mm diameter
measuring area, and diffuse illumination/viewing was utilized. The
tristimulus values of CIE L*, a*, b* readings were calibrated against a
standard white plate. CIE 1976 uniform color space was taken into
account for the colorimetric analysis. Within the CIELAB uniform space,
a psychometric index of lightness, L* (ranging from 0, black, to 100,
white), and two color coordinates, a* (which takes positive values for the
direction of redness and negative values for the direction of the
complement green) and b* (positive for yellowness and negative for
blueness), are defined.21 The data of each measurement are the average
of triplicate measures on equidistant points of the sample.
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