Nondestructive Early Detection of Bruising in Pear Fruit Using Optical Coherence Tomography

Abstract

Pear fruit is susceptible to mechanical injury during harvesting, packaging, and transportation. Optical coherence tomography (OCT) can provide information concerning chemical and microstructural changes of fruit tissues. Therefore, using OCT to evaluate fruit quality is of great significance. In this study, OCT was used for early detection of subtle bruise symptoms underneath the pear peel. First, the signal intensity versus depth in relation to the OCT images of fruit tissue was determined, which was derived from the values of the OCT signal slope (OCTSS) and 1/e light penetration depth (D 1/e ). Furthermore, shaping (α) and scaling (β) indices were estimated by fitting a gamma distribution function to the signal intensity profile. After mechanical injury, OCTSS, α, and β decreased and the D 1/e value increased. Distribution analysis of the relationship between α versus β served as an effective method to identify tissue bruising at an early stage. In conclusion, the results suggest that OCTSS, D 1/e , and the α versus β distribution are closely correlated with bruise injury in pear fruit tissues. Thus, OCT is a promising technology for early and nondestructive bruise detection.Additional key words: light penetration depth, mechanical injury, microstructure, profile distribution, signal slope

Optical Coherence Tomography as a Non-Invasive Tool for Plant Material Characterization in Agriculture: A Review

“…The glands of healthy mandarins generally have an ellipsoidal form, but as the RBD progressed, they severely flattened, became irregular, and decreased in size. The bruise on a pear fruit was also visualized through OCT imaging and a quantitative analysis model was proposed to classify unbruised and bruised tissue automatically [69]. Following boundary detection in the OCT images, A-scan analysis was applied to determine four possible indicators for bruises in pear fruit, including the OCT signal slope, light penetration depth, shaping, and scaling, which were taken into consideration [49]).…”

Early bruising detection of ‘Korla’ pears by low-cost visible-LED structured-illumination reflectance imaging and feature-based classification models

“…Many techniques have been used for bruising detection of pears, including hyperspectral imaging (HSI) ( Lee et al., 2014 ; Fu and Wang, 2022 ; Tian et al., 2023 ), magnetic resonance imaging (MRI) ( Razavi et al., 2018 ; Razavi et al., 2020 ), X-ray computed tomography (CT) ( Azadbakht et al., 2019a ; Azadbakht et al., 2019b ), thermal imaging (TI) ( Kim et al., 2014 ; Zeng et al., 2020 ), Optical coherence tomography (OCT) ( Zhou et al., 2019 ), etc. HSI has been widely used in fruit damage detection and has been proven effective in this regard.…”