Today, the quality evaluation of agricultural products is one of the most crucial post-harvest activities. Quince ( Cydonia Oblonga ) is a native fruit of Iran and due to its high nutritional value, it is considered by other countries. Quince pest ( Euzophera bigella Zeller ) and apple pest ( Cydia pomonella L ) are two important pests that reduce the quality and quantity of the product. Detecting the intact and infested fruits is economically important, however, the infestation has usually no visual symptoms. Therefore, developing a nondestructive technique that can evaluate the quality indices of quince and detect the infested ones in a fast and reliable manner seems to be necessary. In this study, Vis / NIR spectroscopy in two measurement modes of half-transmittance and interactance was used to estimate the maturity indices of quince including soluble solids content (SSC), firmness, and color parameters of L*, a*, and b*. Moreover, the ability of this method was assessed to nondestructive detection of insect infestation of quince. Spectral acquisition system consisted of the major components including adjustable light sources, a PDA spectrometer equipped with high-resolution CCD detector in the range of 1200-200 nm, fiber optic probe, and flexible set up. After collecting the spectra, the samples were cut to ensure the degree and the type of infestation. Then, the intact samples were used to evaluate the quality indices by using the standard methods. Different preprocessing methods were applied to the spectra to eliminate the unwanted information including the noise. Partial least squares (PLS) regression was used for quantitative analysis and soft independent modeling of Key Words : Vis / NIR spectroscopy, Quince, Partial least squares, Soft independent modeling of ltr"
