Use of FI-IR and Miniature Fiber Optic Spectrometers in Measurements of Soluble Solids Content of Pear Juice

Abstract

The objective of this research was to measure soluble solids content (SSC) of pear juice using FT-NIR and USB4000 spectrometer, also the results of FT-NIR and USB4000 spectra were compared. The absorption spectra of 228 pear juice samples were collected by FT-NIR spectrometer with wavelength range of 660-1100 nm and USB4000 spectrometer with wavelength range of 345-1040 nm. The partial least squares regression (PLSR) combined with four spectral pre-processing methods and stepwise multiple linear regression (SMLR) were used to develop calibration models. The results show that both FT-NIR spectra and USB4000 spectra are suitable for assessing SSC of pear juice, and FT-NIR spectra is better than USB4000 spectra to measure SSC of pear juice. The coefficients of determination (R2), root mean square error of calibration (RMSEC) and root mean square error of prediction (RMSEP) for FT-NIR spectra and USB4000 spectra are 0.97, 0.141, 0.167, and 0.85, 0.325, 0.370, respectively. SMLR using sensitive wavelengths for FT-NIR spectra also obtains acceptable results.