Author:

Keywords:

Science & Technology, Technology, Physical Sciences, Remote Sensing, Optics, Spatially resolved spectroscopy, light scattering and absorption, Vis/NIR spectroscopy, metamodeling, FRUIT, 4006 Communications engineering, 4009 Electronics, sensors and digital hardware, 5102 Atomic, molecular and optical physics

Abstract:

A contact spatially resolved spectroscopy (SRS) setup based on a fiber-optics probe in the Vis/NIR range (400-1000 nm) was developed, calibrated, and validated for its measurements and optical properties estimation by means of a metamodeling method on a set of liquid optical phantoms. Thirty Braeburn apples cultivated in sub-fertilization condition were harvested and measured before and after shelf-life storage (2 weeks at 18 °C) by the setup and were analyzed for quality attributes (firmness and soluble solids contents (SSC)) by destructive reference methods. Estimated optical properties (absorption and reduced scattering coefficients) acquired from SRS measurements at the beginning and the end of the shelf-life indicated changes in chemical composition of the apples. Partial Least Squares Regression (PLSR) was employed to construct calibration models relating the estimated optical properties to the reference quality attributes. The constructed PLS models based on the absorption coefficient spectra gave good prediction performance for the quality attributes of the apples in the validation set with correlation coefficients r of 0.901 and r of 0.844, respectively for SSC and firmness. The obtained results clearly show the potential of the SRS measurements for nondestructive quality evaluation of apples. © 2013 SPIE.