Discriminating hidden bruises in loquat by attenuation coefficients estimated from optical coherence tomography images

Hidden bruising is considered as one of the difficulties during loquat quality control, which has made an impact on postharvest quality and storability. Optical coherence tomography (OCT) is used as a non-destructive method that acquires 2D images of the sub-surface structure of the loquat. After OCT image processing, the attenuation coefficients (μt) of the regions of interests are fitted to quantitatively analyze the characteristics of loquat tissue through using a confocal signal scattering model from OCT A-scan signals. In this experiment, a total of 60 loquat samples are investigated, with the non-bruised tissue having a large μt with a mean value of 1910 m−1 (std: ±160). However, bruised groups without any storage time and after storage for 12 h showed lower μt with a mean value of 1190 m−1 (std: ±230) and 1020 m−1 (std: ±190) respectively. The μt value is sensitive to chemical and structural changes in loquat tissue and can also be used in hidden bruise discrimination of loquat.