The objective of this study was to compare transmission and reflectance modes of visible (VIS)/near infrared (NIR) spectroscopy for their ability to nondestructively determination of key pomegranate quality attributes such as total soluble solid content (TSS), pH and firmness. Partial least squares (PLS) regression was used to develop calibration models. The reflectance mode predicted TSS with r = 0.95, RMSEC = 0.22 °Brix and RPD = 6.7 °Brix by calibration models. These parameters for the validation models were found to be: r = 0.94, RMSEP = 0.21 °Brix and RPD = 6.72 °Brix. The pH was predicted with r = 0.85, RMSEC = 0.068 °Brix and RPD = 4.58 °Brix for calibration set and r = 0.86, RMSEP = 0.069 °Brix and RPD = 4.43 °Brix for validation sets by reflectance mode. The results indicated that it was possible to use both the transmissionand reflectance modes to develop a system in determination of the internal attributes of pomegranate fruit. However, reflectance mode spectra provided more accurate assessment of TSS, pH and firmness.

Keywords