Nondestructive measurement of firmness of pear using visible and near-infrared spectroscopy technique

The objectives of this study are to establish mathematical relationship between visible and near-infrared (Vis/NIR) spectroscopy and firmness of pear, and to evaluate the applicability of VIS/NIR spectroscopy technique for nondestructive measurement of firmness of pear. In the spectral region between 350 and 1800 nm, calibration results for firmness of pear were compared with those at different measurement positions, with different spectral pretreatment methods and different calibration modeling algorithms. The results show that the partial least square regression (PLSR) model, with respect to the first derivative spectra (D1log (1/R)) at equatorial position, provides better prediction performance for firmness of pear, with correlation coefficient (r) of calibration and prediction, root mean standard error of calibration (RMSEC) and root mean standard error of prediction (RMSEP) of 0.8779, 0.8087, 1.0804 N and 1.4455 N, respectively. The research results show that nondestructive measurement of firmness of pear using VIS/NIR spectroscopy technique is feasible.