Comparison of detection modes in terms of the necessity of visible region (VIS) and influence of the peel on soluble solids content (SSC) determination of navel orange using VIS–SWNIR spectroscopy

• The necessity of VIS region under three detection modes was evaluated.
• The interference caused by peel was analyzed in terms of three detection modes.
• Transmittance mode provided the performance in VIS–SWNIR and SWNIR region.

Comparison of three detection modes (interactance, reflectance and transmittance) was performed in terms of the necessity of visible (VIS) region and the interference caused by peel in SSC assessment of navel oranges. Spectra of 88 oranges with peel and peeled were collected using a commercial available CCD spectrometer. Partial least squares (PLS) regression was used to develop calibration models. Results showed that the participation of VIS region degraded the performances of PLS models in transmittance mode, while for the other two modes VIS–SWNIR models turned out to be the best. The peel of oranges did not bring about significant negative influence on SSC determination in any detection mode. The best calibration models were achieved with transmittance mode regardless of sample status. Future research should be focused on specific reasons such as the composition of orange peel and the influence of different sizes of fruits.