Non-destructive quality evaluation of intact tomato using VIS-NIR spectroscopy

The potential of visible/near-infrared (VIS/NIR) absorbance spectroscopy in determining the quality of intact tomato (Lycopersicum esculentum), at varying stage of maturity were evaluated in the wavelength range of 299 nm to 1100 nm. Prediction models were built between Vis/NIR spectra and the major fruit properties viz. total soluble solids (TSS), acidity (pH), titratable acidity (TA), and lycopene content by using partial least squares regression (PLS) method. Different pre-processing methods were applied to improve the predictability of the model for each parameter. The best prediction results were achieved using PLS model after orthogonal signal correction (OSC) data treatment at a wavelength range of 370–1040 nm for all tested parameters. The coefficient of determination (R2) for majority of parameters were found to be higher than 0.82 except for TA (R2 =0.77, RMSEP= 4.08), and lycopene (R2 = 0.79, RMSEP = 4.94). The R2 value for TSS and pH were found to be 0.85 and 0.82, respectively. For tomato samples good correlation was found between the quality properties (TSS, pH, TA, and lycopene content) parameters. The standard errors of calibration, prediction, biases and differences in them were low, which indicated that spectroscopy has the potential to predict quality of tomato non-destructively.