Determination of Fruit Ripeness Degree of ‘Carabao’ Mango (Mangifera indica L.) using Digital Photometry
Maja Sierhine J. Abarra1, Edralina P. Serrano2, Veronica C. Sabularse1,
Hervin Errol T. Mendoza1, and Ernesto J. del Rosario1*
1Institute of Chemistry, College of Arts and Sciences,
University of the Philippines Los Baños, Laguna 4031 Philippines
2Postharvest Horticulture Training and Research Center,
College of Agriculture, University of the Philippines Los Baños, Laguna 4031 Philippines
Color photographs of ‘Carabao’ mango fruits at different color index (CI) values or stages of ripeness were computer analyzed based on RGB, HSV, and L*a*b* color spaces. Plots of R, B, V, and L* versus CI had correlation coefficients (R2) of 0.874, 0.915, 0.931 and 0.948, respectively. Titratable acidity (TA) and fruit firmness decreased with CI. Values of R2 for TA were 0.917, 0.915, 0.948, and 0.977 for R, B, V, and L*, respectively; corresponding values for firmness were 0.941, 0.933, 0.941, and 0.968. R2 of the binary and ternary color functions for TA were 0.924 and 0.947, respectively; corresponding values for firmness were 0.905 and 0.948, respectively. The results show that digital photometry – using a simple digital camera and free-access software for color analysis based on RGB, HSV, or L*a*b* systems – is a promising laboratory method for determining the ripeness degree of ‘Carabao’ mango fruits.
Key words: ‘Carabao’ mango, digital photometry, HSV, L*a*b*, RGB, ripeness indicator
Color is determined by light source, reflected light from the sample, and visual sensitivity of the observer. These determinants were defined by the Commission Internationale de l’Eclairage (CIE) in 1931 in order to simulate the visual mechanism based on the primary colors (R, G, B) and color-matching functions. The majority of color digital still cameras intended for technical applications use an array of transistors on a CCD chip, with a filter array that allows some detectors for red (R), green (G), and blue (B). Thus, a digital color image is represented in RGB form with each color component R, G, or B per pixel in the range 0 to 255 and conventionally stored using eight bits per color component. L*a*b* or CIELAB, which is another commonly used and CIE-specified measure of color, may be calculated from XYZ values. . . . . . read more
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