The aim of this study was to evaluate the potential of near-infrared reflectance spectroscopy (NIRS) as a rapid and nondestructive method to determine the soluble solid content (SSC) and pH of intact plums. Samples of plum with total solid contents ranging from 5.7 to 15% and pH from 2.72 to 3.84 were collected from supermarkets in Natal (Rio Grande do Norte, Brazil) and NIR spectra were acquired in the 714-2500 nm range. A comparison of some multivariate calibration techniques with respect to several pre-processing data and variable selection algorithms, such as interval partial least squares (iPLS), genetic algorithm (GA), successive projection algorithm (SPA) and ordered predictor selection (OPS), was performed. Validation models for SSC and pH had a coefficient of correlation (R²) of 0.95 and 0.90, as well as a root mean square error of prediction (RMSEP) of 0.45 and 0.07, respectively. From these results, it can be concluded that NIR spectroscopy can be used as a nondestructive technique for determining SSC and pH in plums.
NIRS; plum; multivariate calibration; variable selection
