Exploring the optical response of water status and light propagation in bruised ‘Korla’ fragrant pear tissues based on low-field nuclear magnetic resonance coupled with Monte Carlo simulation

In this study, the water distribution and migration of bruised ‘Korla’ pear flesh during storage, as well as their relationships with optical properties and light propagation, were comprehensively investigated based on the low-field nuclear magnetic resonance (LF-NMR) coupled with Monte Carlo simulations. The immobilized water clearly transferred to free water during pear tissues bruising. The optical absorption coefficient (μ_a) around 1480 nm was strongly correlated with the LF-NMR T₂ relaxation time of bruised pear tissues by 2D-COS. The reduced scattering coefficient (μ_s') declined with increasing degrees of bruising. In absorption process of bruised pear tissues at 1482 nm, the photons transmission distance from light source increased from 10.76 mm to 15.39 mm. The support vector machines discriminant analysis (SVM-DA) model based on μ_s' in 900–1650 nm provided an accuracy of 95.4 %. These results provided fundamental supports to develop advanced optical models to evaluated the early bruised fruits.