Discriminating between Pithy and Non-pithy 'Mizu-nasu' Eggplant Fruit by Visible or Near-infrared Spectroscopy

Abstract

　We assessed the applicability of an X-ray transmission imaging system and visible or near-infrared spectroscopy for discriminating between pithy and non-pithy 'Mizu-nasu' eggplant fruits. We determined that the X-ray transmission imaging system was not appropriate. Visible or near-infrared spectroscopy was considered suitable for discriminating between pithy and non-pithy fruits. The second derivative values of the absorbances at 712 and 832 nm were applied to the discriminant in a multivariable analysis. The discriminant was as follows: Z＝－1067×D2 (712 nm)－72900×D2 (832 nm)－3.793. Eggplant fruits were harvested from plants cultivated under the same growth conditions as those used to grow plants for developing the discriminant. The harvested samples were examined for the presence of a fruit pith cavity, and the discriminant was evaluated to assess the applicability of the method. The accuracy of the discrimination between pithy and non-pithy fruits was 92%. This finding suggests that the proposed discriminant is suitable for distinguishing between normal and pithy 'Mizu-nasu' eggplant fruits.