Abstract：The objective of the present research was to study the influence of four kinds of light intensity of near-infrared diffuse reflectance spectra on the determination of pear soluble solids content. Qualitative analysis of the four spectra showed that the differences between them were too slight to find. After further analysis by principal component regression (PCR), stepwise multiple linear regression (SMLR) and partial least squares regression (PLSR) as well as comparisons among them, the results of PCR model and SMLR models which had low correlation coefficients (r) were worse than those of PLSR model. The model based on PLSR was further optimized by the second order derivative pretreatments of the spectra, and its correlation coefficients ranged from 0.947 to 0.970. The relative coefficients in PLSR model based on spectra from four sets were 0.958. The results indicate that light intensity has little influence on the determination of pear soluble solids content based on near-infrared diffuse reflection spectra.
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