Estimation of fruit maturation and ripening using spectral indices

Spectral indices can be used in assessment of pigment level of intact plant material, and thus there exists the possibly of using spectral indices as a measure of fruit maturity and ripeness. Spectra of tomato, banana and mango fruit were collected with a Nirvana handheld unit (Integrated Spectronics, Australia). A number of spectral indices: greenness index = R554/R677; DA index = A670-A720; chlorophyll index = R800/R700-1; Car/Chl ratio = (R678-R500)/R750; chlorophyll ratio = (R750/R700) and xanthophyll index = (R530-R570)/(R530+R570) were assessed. Tomato maturity was best discriminated using the Tomato index and carotene/chlorophyll ratio, while mango maturation and banana ripening were best indexed by DA index and chlorophyll ratio.