[Estimation of soluble solids content of apple fresh juice by FTNIR spectroscopy].

The feasibility of Fourier transform near infrared (FTNIR) spectroscopic technology for rapid quantifying the soluble solids content (SSC) of apple fresh juice was investigated by means of spectral transmittance technique. A total of 60 juice samples were used to develop the calibration models. The relationship between laboratory SSC and FTNIR spectra of apple fresh juices was analyzed via principal component regression (PCR) and partial least squares (PLS) regression method using TQ 6.2.1 quantitative software. Models based on different spectral ranges were compared. Performance of different models was assessed in terms of root mean square errors of prediction (RMSEP) and correlation coefficients (r2) of validation set of samples. The best prediction models had a RMSEP of 0.603 degree Brix and correlation coefficient (r2) of 0.997 for SSC. The results show that FTNIR transmittance technique is a feasible, accurate and fast method for non-invasive estimation of fruit fresh juice soluble solids content.